Microbiology 🦠 Flashcards
(221 cards)
1
Q
What is the genus mycobacterium composed of?
A
Around 100 species.
2
Q
What are the most familiar species of mycobacterium?
A
The most familiar species are Mycobacterium tuberculosis (M. tuberculosis), the causative agent of tuberculosis (TB) and Mycobacterium leprae (M. leprae), the causative agent of leprosy.
3
Q
What are mycobacterium classified into?
A
- Members of M. tuberculosis complex:
- Cause tuberculosis in different hosts.
- Examples: M. tuberculosis, M. bovis. - Non-tuberculous Mycobacteria (Atypical Mycobacteria)
- Example: Mycobacterium avium complex (MAC). - M.leprea: The causative agent of leprosy.
4
Q
What are the characteristics of nontuberculous mycobacteria?
A
- Less pathogenic species.
- Not transmitted from human to human (acquired from natural sources).
- Cause infections in immune-compromised patients.
- Resistant to the usual anti-tuberculosis drugs.
- Wide range of diseases: Pulmonary disease that resembles TB, Cervical lymphadenitis, Granulomatus skin lesions & soft tissue infections.
5
Q
What are the properties (key characters) of mycobacteria?
A
- The cell wall contains extremely high lipid content (40-60 %), which is responsible for their staining and cultural characters.
- Acid fastness (Acid-fast bacilli). “Not decolorized by acids”
- Slow growth rate.
6
Q
What is the morphology of mycobacteria?
A
- Straight or slightly curved rods.
- Occurring singly, in pairs, or small clumps.
- Non-motile, Non-spore forming, Non-capsulated.
- Acid & alcohol fast.
- Not stained by Gram.
7
Q
What are the cultural characters of mycobacteria and what is responsible for it?
A
- Strict aerobe.
- 5 - 10% CO2, enhances growth.
- Optimum temperature is 37 °C.
- Very slow grower (may require 2-8 weeks to get visual colonies).
- No growth on ordinary media.
8
Q
What are the media used to grow mycobacteria?
A
Egg-based media:
➢ Lowenstein-Jensen medium.
“Selective medium to isolate TB from contaminated specimens”
➢ Dorest egg medium.
Agar-based media:
➢ Middle brook’s medium.
9
Q
What is the Reservoir and the source of mycobacterium tuberculosis?
A
Humans are the only reservoir and source for M. tuberculosis.
10
Q
What is the mode of transmission of mycobacterium tuberculosis?
A
Mode of transmission: inhalation of infectious airborne droplets.
- M. bovis causes TB in cows, and is transmitted to humans by ingestion of raw “not sterealizd” milk leading to extra pulmonary TB. “GIT TB”
11
Q
What is the virulence mechanism of mycobacterium tuberculosis?
A
The basis for M. tuberculosis virulence is largely unknown
- M. tuberculosis doesn’t produce any toxin.
- Main determinant of virulence is the capability for intracellular growth in alveolar macrophages. “Replicate in phagosome as they prevent the action of lysosomes”
- Main pathology in infected tissue is primarily due to immune response of host rather than any virulence factor produced by it.
12
Q
What are the risk factors for TB?
A
- Small rooms & rooms with poor ventilation.
- Steroids, chemotherapy, malignancies, malnutrition.
- HIV (one of the most important risk factors): Patients with TB should be tested for HIV & those with HIV should be tested periodically for TB. HIV reactivates latent TB infection, makes disease more serious, renders treatment ineffective. “TB is related to HIV”
13
Q
What are the clinical syndromes of TB?
A
A. Pulmonary TB: Affects the lower respiratory system.
Characterized by: (WSAF FC)
➢ Chronic productive cough up to coughing bloody sputum,
➢ Low-grade fever,
➢ Weight loss, “mild”
➢ Night sweats,
➢ Appetite loss
➢ Fatigue.
B. Extra pulmonary TB: due to spread of bacilli through circulation during initial stage of multiplication e.g. Renal TB, Gastrointestinal TB, TB meningitis.
14
Q
What is a laboratory diagnosis for mycobacterium tuberculosis?
A
- Specimen Collection
- Direct smear
- Culture
- Rapid culture method (BACTEC System)
- Intradermal skin test (Tuberculin test)
- Recent methods for diagnosis
15
Q
How are specimen for mycobacterium tuberculosis collected?
A
- Sputum, bronchial or gastric washings (Gastric washings are especially used for young children).
- At least 3 morning samples of sputum are required for diagnosis. “ for 3 successive days”
16
Q
What are the stains used for mycobacterium tuberculosis?
A
Ziehl-Neelsen (Z-N) stain and Fluorochrome stain.
17
Q
What color does mycobacterium tuberculosis give with Zein Nelson stain?
A
Bacilli appear pink in a contrasting blue background
18
Q
What color does mycobacterium tuberculosis give With fluorochrome stain?
A
Bacilli appear as bright yellow on dark background
19
Q
What are the advantages and disadvantages of direct smear?
A
- Advantages: Rapid, Cheap, Simple.
- Disadvantages: Low sensitivity in addition to being non specific
20
Q
What is the definitive method to detect and identify Tuberculosis?
A
Culture
21
Q
What are the disadvantages of direct smear? “In details”
A
• Low sensitivity: (at least 5,000 – 10,000 bacilli/ml
sample should be present to have +ve smear).
• Non specific: (Other AFB are similar to M. tuberclosis in stained smear).
22
Q
What should happen to all positive and negative direct stand smear samples?
A
They should be cultured
23
Q
What are the steps of culture of mycobacterium tuberculosis?
A
- Sputum is inoculated on selective medium (Lowenstein-Jensen), as it contains normal bacterial flora.
- Cultures are incubated in appropriate conditions (see culture Charaters) and are examined weekly for 2-8 weeks (Slow-growing bacillus).
24
Q
What are the advantages and disadvantages of culture of mycobacterium tuberculosis?
A
Advantages:
1. Highly sensitive & specific.
2. Useful for identification and susceptibility testing to antituberculous drugs.
Disadvantage:
long period of incubation (2-8 weeks) to get visual colonies.
25
What is rapid culture method and what time does it take? (BACTEC System)
- M. tuberculosis multiplies in broth media containing radio-labeled palmitic acid (sole carbon source) and release radio-labeled CO2.
- As M. tuberculosis multiplies, it utilizes the palmitic acid and release radio-labeled CO2.
- Growth can be detected in 9-16 days. "2 weeks"
26
What is the principle of intradermal skin (tuberculin test)?
- This test measures the patient’s cell mediated immune response (CMI) to bacterial Ag (tuberculoprotein) in a type IV hypersensetivity reaction.
- Intradermal injection (ID) of PPD (purified protein derivative) into a previously infected hypersensitive person results in the delayed (48-72 hr) appearance of an induration of ≥10 mm.
27
What is the value of tuberculin test in diagnosis?
- Positive reaction means previous exposure to M. tuberculosis (active/past infection). It carries no implication about the activity of the infection.
- Negative reaction means that this person has not been infected with M. tuberculosis (susceptible to infection). "And should be vaccinated"
- The value of tuberculin reaction to diagnose active infection is restricted to children <5 years, but in adults is of value only if negative to exclude infection.
- Recent conversion of the tuberculin reaction from negative to positive needs clinical attention.
28
What are the disadvantages of tuberculin test?
- False positive and False negative results.
29
What are the recent methods for diagnosis of mycobacterium tuberculosis?
A. Hybridization (DNA probe) and Nucleic Acid Amplification Tests (PCR, GeneXpert): Useful for direct detection of Mycobacterial genes in clinical specimen in ≤ 24hrs.
B. Chromatography: A technology that extracts fatty acids from the mycobacterial cell wall and analyze them.
C. QuantiFERON test: "Like tuberculin" ‘In vitro’ assay test of interferon-Gamma which is a component of CMI response to M. tuberculosis.
30
What are the characteristics of the recent methods for diagnosis of TB?
Rapid, specific & sensitive methods.
31
How to prevent and control TB?
1. Adequate nutrition .
2. Good housing.
3. Health education.
32
What is the only licensed vaccine to prevent the development of active TB disease?
BCG Vaccine
33
What is BCG vaccine?
- Live attenuated vaccine prepared from attenuated strain of M. bovis (Bacillus of Calmette and Guerin) by repeated subculture on glycerol-potato-bile medium.
"Mycobacterium tuberculosis was cultured for 250 times over 13 years to give weak TB due to malnutrition"
34
Administration of BCG vaccine.
- Vaccine is given by ID injection to all infants in the first year of life & to tuberculin negative adults.
- Following vaccination, a tuberculin-negative individual → positive reactor (tuberculin conversion) after ~6 weeks.
35
What are the virus causes of respiratory tract infections?
▪ Myxoviridae family
- Orthomyxoviridae.. Include one genus :
✓ Influenza virus
- Paramyxoviridae...Include 3 genera:
✓ Paramyxovirus (parainfluenza viruses and mumps virus);
✓ Pneumovirus (respiratory syncytial virus);
✓ Morbillivirus (measles virus).
▪ Coronaviridae family: Corona virus
▪ Adenoviridae family: Adenovirus
▪ Picornaviridaefamily: Human rhinoviruses
36
What is the morphology of influenza virus?
- Influenza virus particles are highly pleomorphic, 80-120 nm in diameter., The genome consists of Segmented (-) sense, s/s RNA in 8 segments (7 in Influenza C).
" - sense means can't act directly as mRNA"
- The outer surface of the particle consists of a lipid envelope from which project prominent glycoprotein spikes of two types:
a) Haemagglutinin (HA).
b) Neuraminidase (NA).
- The inner side of the envelope is lined by matrix protein (MP).
37
How are virus strains classified? ”influenza”
- Is done on the basis of antigenicity of nucleoprotien "in RNA" (NP) and matrix protien (MP) into three main groups A, B and C.
- Influenza A is classified into subtypes according to HA (16) and NA (9). "GP spikes"
38
What is antigenic shift and how common is it?
• This refers to major dramatic changes in the H and/or N proteins, which occurs when a cell is infected with two genetically distinct influenza virus......Undergoes reassortment
• Every 10-20 years and involves change in subtype
39
In which type of influenza does antigenic shift occur?
Type A
40
What is the definition of antigenic drift and how common is it?
- This refers to minor antigenic changes in the H and N protein that occur each year.
- Does not involve a change in the viral subtype.
41
In which type of influenza does antigenic drift occur?
A & B
42
Which of antigenic shift or antigenic drift cause pandemics and epidemics?
Antigenic shift
43
What is the source of influenza?
human beings .
44
How is influenza spread?
- rapid via respiratory droplets, Rapid spread leads to epidemics.
45
What is the incubation period of influenza?
- short (1-3 days). Rapid spread leads to epidemics.
46
What are the symptoms of infection with influenza?
- is characterized by fever "39 or above", myalgia "pain in ,muscles", headache and pharyngitis.There is usually no coryza ( no runny nose)
47
What are the complications of infection with influenza?
1. Pneumonia caused by influenza virus itself.
2. Pneumonia caused by bacteria "Secondary to viral infection" : S. aureus, Haemophilus influenza, or Stept. pneumoniae.
3. Other viral super-infection, e.g. Adenovirus..
48
How is influenza diagnosed?
• Samples: Respiratory secretions, by aspirate, gargle or nasal washings used for:
a) Rapid examination of cells by IF for antigen detection.
b) Inoculation of cell cultures (or eggs).
• Serology: By detection of antibodies in the serum by haemagglutination inhibition (HAI).
• Molecular Techniques: By RT-PCR
49
How is influenza treated?
Several anti-influenza drugs exist.
• Amantadine and Rimantadine are active against influenza A (but not B viruses).
• Zanamivir by inhalation and oseltamivir (Tamiflu) orally: inhibit viral neuraminidase which is present in both influenza A and B viruses and is necessary for viral release from the infected cell.
50
What are the vaccines for influenza and what are their characteristics?
• Formaline inactivated vaccine:
✓ Produced by virus growth in embryonated egg.
✓ The vaccine is given IM once for adults every year (annually)
✓ For children it may be given twice 4 weeks apart according to the age.
• Much interest in other types of vaccine, especially: genetically engineered/subunits and Live attenuated vaccine (LAV).
51
What is avian influenza and what is it characterized by?
• Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus.
• Highly pathogenic avian influenza is characterized a mortality that can approach 100% of the infected birds.
52
What are avian flu strains that can be transmitted from birds to human?
H5N1 and H7N9
53
What are the symptoms of infection with pathogenic strains of avian flu to humans?
• Infection is transmitted form birds to human but no Human to Human transmission is documented.
• Stomach upset and diarrhea may occur with avian influenza.
54
Is there a vaccine for avian flu?
• There is no vaccine for humans but bird vaccination is available.
55
What is swine flu and does it affect humans?
• Type A influenza of pigs and does not normally infect humans.
56
What are the variants of swine flu that infect humans and when did they appear?
• However, in 2009 a new H1N1 swine flu variant appeared with the ability to infect humans.
• In 2011, another swine flu strain (H3N2) appeared.
57
What does the subfamily Paramyxoviridae contain?
- This sub-family contains parainfluenza viruses (1, 2, 3 and 4), measles virus, mumps virus and respiratory syncytial virus (RSV).
58
What is the morphology of paramyxoviruses?
• Paramyxoviruses are composed of one piece of ssRNA, a helical nucleocapsid, and an outer lipoprotein envelope.
• The envelope is covered with spikes, which contain haemagglutinin, neuraminidase, and a fusion protein that causes cell fusion (form large multinucleate giant cells)
59
What do paramyxoviruses infect?
- Usually occur in (early) childhood, however, re-infections do occur in adulthood, but disease is sub-clinical or very minor.
60
How are paramyxoviruses spread?
- By droplets from the nose and mouth to fairly close contacts.
61
What do para influenza viruses cause?
• Cause acute laryngo-tracheo-bronchitis in children.
• Can cause pneumonia. "Complication"
62
How are para influenza viruses diagnosed?
• Detection of the viral RNA by RT-PCR.
• Detection of the viral antigens or antibodies by EIA and IF.
• Virus isolation: on cell culture and detection of cytopathic effects.
63
How are para influenza viruses treated?
• No specific treatment is available.
• No specific vaccine is available.
64
How is mumps virus transmitted?
Spread by the respiratory route.
65
What is the incubation period of mumps virus?
- has a relatively long incubation of about 21 days.
66
What is the clinical picture of mumps virus?
- It causes inflammation of the salivary glands, classically the parotid and submaxillary glands.
67
What are the complications of mumps virus?
1) Aseptic (viral) meningitis
2) Mumps meningoencephalitis: is rarer but a more serious development.
3)Orchitis: can occur, more often after puberty, unilateral or bilateral, but is rarely followed by infertility. "Only if bilateral"
4) Other glandular tissue is very occasionally involved e.g. pancreatitis, oophoritis or thyroiditis.
68
How is mumps virus diagnosed?
• Isolation of the virus from saliva, CSF "in case of meningitis" or urine by culture on monkey kidney cells.
• Serologically: Confirmed Diagnosis by positive IgM antibodies by using CF, HI and ELISA.
69
How is mumps virus prevented?
- Live attenuated virus vaccine given in MMR vaccine.
70
which virus is considered as one of the most infectious disease is known?
Measles
71
How is measles virus transmitted?
Transmission is by respiratory route (airborne). The virus can also infect via the eye and multiply in the conjunctivae.
72
What is the incubation period of measles virus?
10-12 day
73
What is the clinical picture of infection was measles virus?
- Prodromal "initial" phase is characterized by fever, dry cough,
sore throat, conjunctivitis, and Koplik's spots (raised red spots with white centers in the mouth). After few days, the characteristic red, maculopapular rash starts on the head and then spreads to body. "Behind the ear"
74
What are the complications of infection with measles virus?
1) Bronchopneumonia and otitis media
2) Encephalitis occurs in ~1:2000 cases.
3) Subacute sclerosing pan encephalitis: It is a chronic infection in which the virus multiplies in the brain resulting in neurodegenerative disease. "Characteristic"
75
How is measles virus diagnosed?
- Measles is easy to diagnose clinically. Laboratory diagnosis is rarely needed.
76
How is measles virus prevented?
- Trivalent live attenuated vaccine (MMR) is usually given by sub cutaneous injection. It is given at 12 – 15 months age. A single dose of the MMR vaccine gives around 90% protection against measles and mumps and 95-99% against rubella.
77
How is measles virus treated?
• No specific drugs.
• Symptomatic treatment only.
78
What is the Characteristic thing about the morphology of respiratory syncytial virus?
- RSV resembles the other members of Paramyxoviruses morphologically, but it has no haemagglutinin or neuraminidase
"Even though it belongs to Paramyxoviridae"
79
What is the prime cause of bronchiolitis? "in children"
RSV
80
What is the common disease that is linked to RSV?
- RSV may be linked to epidemics of asthma and has been identified as an exacerbating factor in other diseases
81
What is the morphology of coronavirus?
- Coronaviruses are single stranded RNA enveloped viruses. They are named for the crown-like spikes on their surface.
82
What is the frequency of mutation of coronavirus and is this usual for an RNA virus with unsegmented Genome?
• Coronaviruses exhibit a high frequency of mutation. "New strains"
• This is unusual for an RNA virus with a nonsegmented genome and may contribute to the evolution of new virus strains.
83
What are the coronaviruses that can infect human?
• Seven coronaviruses that can infect human were identified till now and among them:
✓ SARS-CoV, the coronavirus that causes severe acute respiratory syndrome (SARS).
✓ Middle East respiratory syndrome coronavirus (MERS-CoV) "Saudi SARS”
✓ SARS-CoV-2, the virus causing the current pandemic of COVID- 19
84
How is coronavirus transmitted?
• Coughing and sneezing:(droplet vs air-borne)
"Air-borne transmission happens in special circumstances like in medical actions in the hospital"
• Close personal contact, such as touching or shaking hands.
• Coronaviruses are zoonotic, meaning they are transmitted between animals and people
85
What is the clinical picture of infection by COVID-19?
• Patients with confirmed COVID-19 infection have reportedly had mild to severe respiratory illness with symptoms of: *Fever *cough *shortness of breath....
• Symptoms of COVID-19 may appear in as few as 2 days or as long as 14 after exposure.
86
How is coronavirus diagnosed?
• Nose and throat swabs are the best specimens for detecting common human coronaviruses. Serological testing requires collection of blood specimens.
87
How is COVID-19 diagnosed?
✓ Specific laboratory tests include (RT-PCR) and serology for detection of specific antibodies
✓ Non specific laboratory tests include detection of elevated CRP, serum ferritin, LDH and D-dimmer. CBC shows lymphopenia.
✓ Radiological diagnosis of pneumonia: chest X-ray and CT
88
How is coronavirus treated?
• There are no specific treatments for illnesses caused by human coronaviruses.
89
How is COVID-19 treated?
- Symptomatic treatment......
- Antiviral drugs: non specific
- Others : immunomodulators.
90
How is COVID-19 prevented?
• Nonspecific measures:
✓ Frequently wash your hands
✓ Wear Mask / Practice respiratory hygiene
✓ Maintain social distancing
✓ Avoid overcrowding and closed badly ventilated areas
• Specific measures (vaccines(:
✓ Killed inactivated vaccine "senopharm - senophac" vs mRNA vaccine.... "phyzer"
91
What is the morphology of Adenoviruses?
• Adenovirus is a double stranded DNA icosahedral non-enveloped virus.
92
How many serotypes are found for adenoviruses?
• There are more than 50 human serotypes of adenoviruses in 6 groups (A-F)
93
What is the method of infection by adenoviruses?
Infection occurs by droplets, feco-oral or contact.
94
What are the diseases that may be caused by adenoviruses?
Diseases caused by adenoviruses are:
1- Respiratory: febrile pharyngitis & pneumonia
2- Eye infections, conjunctivitis and keratoconjunctivitis.
3- Gastroenteritis in infants.
4- Acute hemorrhagic cystitis in children "very dangerous"
5- Immunocompromised e.g. AIDS patients may suffer fatal adenovirus infections.
95
what is the definition of picornavirdae?
Name: 'Pico (Greek = very small) RNA Viruses'.
96
How many genera does picornaviridae contain?
The most recent revision of virus taxonomy has recognized nine genera within the family. The most important of them are:
1) Enterovirus : Poliovirus, Coxsackie, echo viruses.
2) Rhinovirus : Human rhinovirus.
3) Hepatovirus : Hepatitis A virus
97
What is the morphology of human rhinovirus?
Small RNA viruses similar to other Picornaviruses.
98
What are the characteristics of human rhinoviruses?
They are relatively fragile viruses, with optimum growth temperature of 33°C
99
What is caused by HRV?
They cause 'the common cold‘. About more than 150 serotypes are identified (hence repeated infections can occur easily).
100
For how many days is infected person by humanrhinovirus can be infectious?
An infected person is infectious in the first two days of coryza
101
What are the causes of bronchitis?
1. Respiratory viruses (Most common)
2. Bacterial causes (less common)
– Mycoplasma pneumoniae, Chlamydia pneumoniae, Bordetella pertussis, B.parapertussis, Haemophilus influenza
102
What is the definition of pneumonia?
Infection and inflammation of the lungs.
103
What is the classification of pneumonia?
Typical pneumonia
Atypical pneumonia
Community acquired pneumonia
hospital acquired pneumonia
104
What are the symptoms of typical pneumonia and what is the most common cause of it?
- high fever, productive cough, diffuse infiltrates, most common cause Streptococcus pneumoniae
105
What are the symptoms of atypical pneumonia and what is the most common cause of it?
- low fever, dry cough, diffuse infiltrates, most common cause Mycoplasma pneumoniae
106
What are the characteristics of atypical pneumonia?
-The disease does not resemble pneumococcal pneumonia.
- Causative organism cannot grow on routine media in diagnostic laboratory.
107
What is the definition of community acquired pneumonia and what are the organisms causing it?
pneumonia presenting within the community, or within 48 hours of hospital admission
- check notes for organisms
108
What is the definition of hospital acquired pneumonia and what are the organisms causing it?
- pneumonia presenting >48 h after admission to hospital
Organsims causing hospital aquired pneumonia
- Gram-negative bacilli (eg Pseudomonas aeruginosa, Klebsiella pneumonia)
Staphylococcus aureus
Streptococcus pneumoniae
Haemophilus influenzae
Legionella spp.
109
What are nosocomial pathogens most likely resistant to?
- Nosocomial pathogens are likely to be resistant to multiple antimicrobial agents.
110
What is the morphology of streptococcus pneumoniae?
- Gram positive cocci, lancet shaped cocci, diplococci, non motile, non spore forming and Capsulated, the capsules appears as unstained halos around the cocci.
111
What are the virulence factors of Streptococcus pneumoniae?
- The main virulence factor is Polysaccharide capsule as it resists phagocytosis.
- It is classiffied into 80 serotypes according to antigenic structure of the capsule
112
What are the diseases caused by streptococcus pneumoniae?
- The most frequent cause of pneumonia and its complications: bacteremia, meningitis, septic arthritis, endocarditis.
- It is common cause of: sinusitis, acute bacterial otitis media, conjunctivitis.
113
What are the laboratory diagnoses of pneumococcal pneumonia?
1. Sample
2. Direct film stained with Gram stain: for characteristic morphology.
3. Culture
4. Identification of Growth
114
what is the sample used for the diagnoses of pneumococcal pneumonia?
Sputum "rusty with blood"
115
what are the culture requirements and the culture media for streptococcal pneumonia?
a) Culture requirements: O2: Facultative anaerobes, optimum temperature is 37°C, grow in normal atmospheric CO2 concentration, but grows better in excess CO2.
"O2 and co2 enhance the growth but arm's essential"
b) Culture media:
Ordinary media: Cannot grow on it.
Enriched media: Grow on blood agar, colonies are small with central depression surrounded by zones of α hemolysis.
116
How is identification of growth of streptococcal pneumonia done?
"To differentiate from strep viridains"
a) Film stained by Gram stain to show the morphology.
b) Biochemical reactions: Ferment inulin, bile soluble. "Clear when bile solubility is positive"
c) Sensitive to optochin.
d) Pathogenicity to mice: Intraperitoneal injection of culture into mice death in 18-48 hours due to septicaemia.
e) Capsular swelling reaction (Quellung reaction): Swelling of the capsule after addition of specific polyvalent antibodies
117
What is the prevention of pneumococcal pneumoniae?
- Pneumococcal Vaccine:
Contains purified capsular material from most pathogenic 23 strains, Recommended for young children, elderly and debilitated persons
118
What are the causative agent of atypical pneumonia?
- Mycoplasma pneumoniae, Legionella pneumophilla Chlamydia pneumoniae Chlamydia psittaci Coxiella burnettii
119
What is the morphology of mycoplasma pneumoniae?
- This is group of very small organisms, Lacking cell walls and highly pleomorphic. The cytoplasmic membrane contains sterols acquired from media or tissue.
"Not synthesized by it"
"Not affected by antibiotics that affect the cell wall"
120
What are the manifestations of infection with mycoplasma pneumoniae?
Pharyngitis , Bronchitis , Primary atypical pneumonia
121
What are the methods of diagnosis of mycoplasma pneumoniae?
"No direct smear by gram as it has no cell wall"
1. Specimens
2. Culture
3. Molecular techniques
4. Sero-diagnosis: The mainstay of diagnosis.
122
What are the specimens used for the diagnosis of mycoplasma pneumoniae?
sputum, throat swab or nasopharyngeal secretions.
123
What is mycoplasma pneumoniae cultured on?
- On enriched fluid media or special mycoplasma agar, give mulberry colonies after several days of incubation.
- Colonies can be identified by staining directly on agar with fluorescein-conjugated antibody or by demonstrating growth inhibition on adding specific antiserum.
124
What are the molecular techniques used for the diagnosis of mycoplasma pneumoniae?
- DNA probes and PCR: detection of organisms in the respiratory specimens.
125
What is the Sero-diagnosis of mycoplasma pneumoniae?
- The mainstay of diagnosis.
- Specific antibodies detection by complement fixation, indirect hemagglutination and latex agglutination tests.
- Non-specific Ab detection by cold agglutinin test: agglutination of group O RBCs (non specific&+ve only in 1⁄2 of cases).
126
How is mycoplasma pneumonia controlled and treated?
- There is no certified vaccine for M. pneumoniae.
- Treatment by Tetracyclines, macrolides, and the newer quinolones
127
What is the morphology of Legionella?
- Legionella pneumophila are pleomorphic Gram negative bacilli, motile, non sporing.
128
What is the pathogenesis (source of infection and mode of transmission) of legionella?
Source of infection:
• Water, particularly the surface waters of rivers and lakes
• Air-conditioning water cooling tanks
Mode of transmission:
• Inhalation of aerosolized mist from contaminated water source.
• Disease may occur in the community or in hospitals (through aspiration, contaminated water, or respiratory equipment).
• No person-to-person
129
What are the virulence factors of legionella?
facultative intracellular pathogen. "LIKE TB"
130
What are the clinical manifestations of infection with legionella?
1. Legionnaires disease: Acute atypical pneumonia that may occur sporadically or in outbreaks.
2. Pontiac fever: Non pneumonic epidemic of influenza like illness.
131
What is the laboratory diagnosis for legionella?
1. Specimens
2. Culture
3. Direct detection of bacterial antigen in clinical specimens
4. Serologic diagnosis
132
What are the specimens used for the diagnosis of legionella?
- Sputum, pleural fluid, transtracheal aspirations and bronchoalveolar lavage
133
What are the culture properties and culture media for legionella?
- Strict aerobic.
- The medium of choice is buffered charcoal-yeast extract medium (BCYE). The bacteria produce small colonies after 3–5 days.
134
How is legionella directly detected?
- Direct detection of bacterial antigen in clinical specimens: By direct immunofluorescence or radioimmunoassay which is faster than culture
135
How is the Serological diagnosis of legionella?
- Detection of specific antibodies (IgM and IgG) in serum
136
How is legionella controlled and treated?
- There is no vaccine.
- Periodic superheating of water and continuous
- chlorination
- The drug of choice is erythromycin
137
What is the definition of chlamydiae?
- Obligate intracellular bacteria, as they are unable to synthetize ATP and depend on the host cell to supply them with ATP and energy requirements.
138
What are the characteristics of chlamydiae that confuse it with bacteria?
- Originally, Chlamydia thought to be viruses but they show the following properties of bacteria:
1. They contain both DNA and RNA.
2. They have Gram negative cell wall.
3. They contain prokaryotic ribosomes.
4. They multiply by binary fission.
5. They are susceptible to many antibiotic
139
What are the diseases caused by chlamydiae?
- Chlamydia pneumoniae:
Pneumonia, bronchitis, pharyngitis
- Chlamydia psittaci:
Psittacosis, ornithosis
- Chlamydia trachomatis:
Nongonococcal urethritis, Trachoma, Inclusion conjunctivitis of the newborn, Pneumonia of newborns, Lymphogranuloma venereum
140
What is the developmental cycle of Chlamydiae?
- The infectious elementary body enters the cell by endocytosis and develops into the noninfectious reticulate body (RB) within a cytoplasmic vacuole, which divide by binary fission to form particles which after synthesis of the cell wall develop into new infectious elementary body and is released to infect other cells.
141
Compare between elementry body and reticulate body according to
Size
Extra or intra-cytoplasmic
Infectious or not
Replication
Site
Size: small - large
Extra or intra-cytoplasmic: extracellular -intracellulaire
Infectious or not: yes - no
Replication: no - metabolically active active and replicating
Site: released from ruptures infected cells - within cells, the site of replication appears as an inclusion body, which can be stained and visualized microscopically
142
What is the laboratory diagnosis of chlamydial infection?
Specimens
Microscopic examination
Culture
Serological tests
Molecular techniques
143
What are the specimens used for the diagnosis of chlamydiae?
- Sputum, scrapings from eyes or the urogenital tract, urethral, cervical exudates.
144
What is the microscopic examination done for the diagnosis of chlamydiae?
- Inclusion bodies are detected by staining with Giemsa or iodine. Staining with fluorescent monoclonal antibodies.
145
What is chlamydiae cultured on?
- On McCoy cells, after incubation, typical cytoplasmic inclusions are seen.
- C pneumoniae grows better inhuman lines HL, HEp-2 cells
- Yolk sac of embryonated egg
146
What are the serological tests done to diagnose chlamydial infection?
a) Detection of chlamydial antigen directly in specimens by using specific immunofluorescent antibodies. (the most sensitive method for diagnosis of C pneumoniae infection)
b) Detection of anti-Chlamydia antibodies in sera and tears from infected humans by complement fixation or microimmunofluorescence tests.
147
What are the molecular techniques used to diagnose chlamydiae?
a) DNA probes: to diagnose C. trachomatis in tissue specimens.
b) Polymerase chain reaction(PCR).
148
What is the treatment of chlamydiae?
Tetracycline and erythromycin
149
What are is the normal microbiota (flora) of the respiratory system?
1. Nose: Staphylococcus epidermidis and Diphtheroids.
2. Pharynx: Haemophilus, Pneumococci and Mycoplasma.
150
What are the types of upper respiratory tract infections?
- Typical infections of the upper respiratory tract include: tonsillitis, pharyngitis, laryngitis sinusitis, otitis media.
151
What are the symptoms of upper respiratory tract infections?
1. Cough, runny nose, sneezing
2. sore throat, nasal congestion
3. low grade fever, headache, facial pressure.
152
How do the organisms from the nose or throat reach the middle ear?
via the Eustachian tube
153
What are the causative organisms of otitis media? "Literally everything"
1. Staphylococcus aureus
2. Streptococcus pneumoniae
3. Streptococcus pyogenes
4. Pseudomonas aeruginosa
5) Klebsiella pneumoniae
6) Proteus and anaerobic bacteria
7) Haemophilus influenza
8) Fungal infection may occur.
154
How is otitis media diagnosed?
1. Swabs are taken from discharge.
2. Culture is done blood agar and nutrient agar plates at 37°c for 24 hours.
3. The isolated colonies will be examined for each type of organisms
155
What are the causative organisms of sore throat?
"Bacterial, viral & fungal"
1. Acute follicular tonsillitis: is caused by Streptococcus pyogenes, Staphylococcus aureus and Streptococcus viridans.
2. Diphtheria. "Gram + bacilli"
3. Vincent’s angina.
4. Herpes febrilis virus (aphthous stomatitis).
5. Candida albicans infection.
156
What are the membranous infections of the tonsil caused by?
"Pseudomembrane on the tonsils"
1. C. diphtheriae
2. Streptococcus pyogenes
3. Vincent’s angina: caused by anaerobic bacteria, particularly Fusobacteria "gram - bacilli" and spirochete "spiral" species.
157
What are the characters of pertussis?
• B. pertussis is strict human pathogen, not present in normal human flora. "Pathogen if found in film"
• Pertussis is a common and dangerous childhood disease in unvaccinated populations.
158
How is pertussis transmitted?
1. inhalation of droplets expelled in cough spray
2. contaminated objects
159
What is the pathogenesis of pertussis?
1- Bacteria colonize only ciliated cells of the respiratory mucosa, and they multiply rapidly.
2- Adherence of B pertussis to human cilia is effected by a synergistic action of pertussis toxin and filamentous hemagglutinin (fimbrial-like structure).
160
What are the virulence factors of pertussis?
Adherence of B pertussis to human cilia is effected by a synergistic action of pertussis toxin and filamentous hemagglutinin (fimbrial-like structure).
161
What is the clinical picture of pertussis?
- The disease pertussis has two stages:
After an incubation period of 1 to 2 weeks
• whooping cough begins with the catarrhal phase (colonization)
• lasts 1 to 2 weeks
• characterized by fever, malaise, rhinitis, and cough; patient is highly infectious.
The second paroxysmal (toxemic) phase,
• lasting 2 to 4 weeks
• Toxins cause injury of ciliated cells and
is characterized by paroxysmal coughing that often ends in a characteristic inspiratory gasp (whoop). "Due to excessive coughing (expiration)"
162
What are the specimens used in the diagnosis of pertussis?
- Nasopharyngeal swab or secretions
163
What are the culture characters of pertussis?
1. It is a strict aerobe
2. slowly growing, need incubation for 3-7 days.
3. B. pertussis is nutritionally fastidious
164
What are the types of media that pertussis needs?
4. no growth on common laboratory media
5. need rich media supplemented with blood.
6. The widely used medium is Bordet-Gengou agar
containing blood, potato extract and glycerol or charcoal-horse blood agar (Regan-Lowe) .
165
What is the shape of the colony of pertussis?
7 . Colonies are glistening with appearance of bisected pearl and narrow zone of haemolysis around
8. Colonies are identified by film stained by Gram to show the morphology, biochemical reactions and slide agglutination with specific antisera.
166
What is the morphology of pertussis?
- small Gram-negative cocobacilli with bipolar staining
- non motile,
- encapsulated
- non sporulated
167
What are you biochemical reactions used in determination of pertussis?
1) oxidase positive but urease negative
168
How is pertussis prevented and treated?
- Prevention by a killed whole bacterial vaccine is administrated as DPT combination and treatment is by erythromycin.
Vaccination is given in the second and fourth and six months and the booster vaccination is given in the 18th months and before school entry"
169
What are the characters and morphology of Haemophilus?
"Parvobacteria"
"Like b. Pertussis but bigger"
1) Gram negative bacilli, non motile, non sporing, capsulated
2) Grow in presence of blood and growth factors (X: haematin and V: coenzyme II) e.g. Chocolate agar
3) Satellism is marked with Staph. aureus. "Growth of Himflus around staph as it secrets growth factors"
170
What are the species of Haemophilus?
1) H. influenza : O.M., Sinusitis, bronchopneumonia, and also meninigitis
2) H. cojunctivitidis : acute mucopurulent conjunctivitis
3) H. ducreyi : Soft chancer” Chancroid”. "STI"
171
How is haemophilus diagnosed?
1) Sputum, Pus, C.S.F.
2) Direct films
3) Culture: grows in presence of blood and growth factors (X: haematin and V: coenzyme II) e.g. Chocolate agar
172
How is haemophilus treated?
Penicillin, Cephalosporins
173
What is the definition of urinary tract infections?
- Infection that occur in any area of the urinary tract, including the ureters, bladder, kidneys, or urethra
174
What are types of urinary tract infections?
1- Upper Urinary tract infection
2- Lower Urinary tractInfection
3- Bladder infection (cystitis)
4- Urethritis
5- Pyelonephritis
175
What type of urinary tract infection develops first?
- Lower Urinary tract Infection
176
What is the cause of upper urinary tract infection?
Due to Progression of untreated Lower Urinary tract infection.
177
What is the most common urinary tract infection?
Bladder infection.
"التهاب المثانة هو اشهر حاجة"
178
What is pyelonephritis and what does it lead to?
- Kidney serious infection requires urgent treatment.
- Lead to reduced kidney function & possibly even death in untreated, severe cases.
179
What are the signs and symptoms of cystitis?
Dysuria, urgency, & frequency.
180
What are the signs and symptoms of pyelonephritis?
"Dangerous"
Flank pain with tenderness, dysuria & urgency.
"In the place of the kidney"
181
What are the causative agents of urinary tract infections?
1- E.coli
2- Klebsiella
3- Proteus
4- Pseudomonos
5- S. aureus - S. epidermidis - S. saprophyticus
6- Strept fecalis
7- Mycobacterium tuberculosis
8- Ureaplasma urealyticum & Chlamydia.
182
What are the most common pathogens for urinary tract infections?
(E. coli (80%), Klebsiella, Proteus & Pseudomonas)
183
What is the …. Of E-Coli and Klebsiela respictevily?
Shape
Stain
Spore
Motility
Arrangement
Capsule
Conditions
PH
Temp
Media
1- Ordinary media
2- MacConeky's agar
Shape
-Rod "bacilli"
-Rod "bacilli"
Stain
-Ve
-Ve
Spore
-Non Sporulated
-Non Sporulated
Motility
-Motile by peritrichous flagella
-immotile
Arrangement
-Single, pairs, groups
-Single, pairs, groups
Capsule
-Capsulated
-Capsulated-polysaccharide
Conditions
-Facultative anaerobic
-Facultative anaerobic
Conditions
-0.03% CO2
-0.03% CO2
PH
-7.4
-7.4
Temp
-37
-37
Ordinary media
-Grow
-Grow
MacConeky's agar
-Rose pink colonies
-Pink, large & mucoid colonies due to polysaccharide capsule
184
What are the serological characters of E.Coli?
1- K antigen (Capsular)
2- O antigen: heat-stable somatic Ag, about 170 types
3- H antigen: flagellar antigen, about 56 types
185
What is the normal habitat for E. coli?
intestinal flora.
186
What does presence of E.Coli in water indicate?
- Principle indicator of fecal pollution of water.
187
What are the serological characters of klebsiella?
1- K antigen (Capsular polysaccharides Variable (77 types)
2- O antigen: lipopolysaccharide
188
What is the normal habitat of klebsiella?
skin, respiratory & intestinal tract.
189
Where is klebsiella saprophytic?
Saprophytes in soil & water.
190
What is the laboratory diagnosis of E. coli and klebsiella?
Sample: Urine, pus, sputum "Acc to site of infection"
Direct film: Gram stain for morphology -+ wi
Culture: See before
Identification of colonies: Stained by Gram stain &
biochemical reaction:
1- Ferment > Maltose, Glucose, lactose and sucrose producing large amount of gases gases & acids
2- In IMVC test (MI) : (+ Ve-> Methyl red & Indol)
(-Ve-> Indol & Methyl red ) "E.coli"
2- In IMVC test (CV)
(-Ve-› Voges-Proskauer & citrate)
(+Ve-> citrate & VP) "klebsiella"
Detect O, H, K antigen "e-COli"
To detect antigens (O-K) "klebsiella"
191
What are the diseases caused by E. coli?
"Intestinal and extra-intestinal"
- Neonatal meningitis
- Nosocomial infection -> UTI, surgical wound infection, bacteremia & Pneumonia.
- Urinary tract infection -> Responsible for 90% of the cases "most common".
- Intestinal disease ( T-I-P-A-H)
192
What are the characters of ETEC?
Causes diarrhea in infants & travelers acquired by ingestion of contaminated food & water.
193
What are the characters of EIEC?
Causes dysentery & fever -+ identical to Shigella dysentery.
"Watery bloody mucous diarrhea"
"Necrosis of epithelium ----> exposure of BV"
194
What are the characters of EPEC?
Induces watery diarrhea.
"Destruction of the microvilli inhibits réabsorptions"
195
What are the characters of EAggEC?
Associated with non-bloody persistent diarrhea in young children.
"Block the channels of water Absorbtion"
196
What are the characters of EHEC?
Has toxic effects on kidneys (hemolytic uremia) life-threatening.
"No Execretion of urea"
197
What is a Microbial pathogenesis and virulence factors of E. coli?
BFFLPS
1-Fimbriae: Adherence to mucosal surfaces.
2- Flagella: Motility help in the fight for nutrients in the urine & enhance bacterial dissemination.
3- A biofilm : Protect bacteria against environmental stress, phagocytosis & antibiotics.
4-Lipopolysaccharides (LPS) : Protection against the human immune system.
5- Many UPEC secrete toxins: Damage host tissues or disable the host immune system. Such as ( a-hemolysin & Cytotoxic necrotizing factor 1 (CNF1) )
6- Bacteria need iron ions to: colonize the urinary tract.
E. coll strains express different types of siderophores *scavenge iron from the environment.
198
What are the virulence factors of klebsiella?
"KBS"
• Capsule : Capsule protects the bacterium from phagocytosis by polymorphonuclear granulocytes
• Adhesions or colonization factors: adhere to cells of tissue surface by special types of Pili.
• Siderophore production: Siderophore supply iron to the bacterial cells .
199
What are the virulence factors of Proteus?
"MTEQA"
• Adehisins: Bacterial adhesion to the uroepithelium "cystitis" is an essential step for colonization and infection.
• Motility: P. mirabilis is a flagellar peritrichious bacterium and has swarming motility ability.
• Toxins: Hemolysin is a toxin forming pores, causing the efflux of ions and subsequent cell damage
• Enzymes : Urease it hydrolyse urea to ammonia and carbon dioxide, there by increasing the pH and facilitating stone formation. "Proteus = stone formation"
• Quorum sensing
Cell-cell communication is utilized bacteria to sense population density and coordinate gene expression.
"Bynado 3la b3d"
200
What are the virulence factors of pseudomonas?
"MTEQ SB"
• SIDEROPHORES: Pyoverdine and pyochelin are siderophores produced by P. aeruginosa
"صبغات عبارة عن مصدر للحديد"
• TOXINS: P. aeruginosa can produce a variety of toxins.
• BIOFILM FORMATION: enhances its ability to resist antibiotics and hard environmental conditions.
• OTHER SECRETED ENZYMES: The vast majority of P. aeruginosa isolates are proteolytic and elastolytic .
• QUORUM SENSING: QS signal molecules (acyl-homoserine lactones, AHL) are expressed.
• MOTILITY: Motility can be an important factor in allowing P. aeruginosa to colonize.
201
What are the species of klebsiella?
- Four species are associated with human diseases, K. pneumonia, K. rhinoscleromatis, K.oxytoca, and K. ozanae.
202
What are the diseases of klebsiella?
- Pneumonia, urinary tract infection, wound infections, bacteremia, meningitis and diarrhea by enterotoxigenic strains.
203
What are the host factors which affect UTI?
"More common in females"
- Certain patient groups display greater susceptibility to UTIs:
1. Being female.
2. Very young or elderly.
3. Structural and functional abnormalities of the urinary tract.
4. Several genes associated with increased risk to UTIs.
204
What are the morphology of Pseudomonos and Proteus respectively?
- It is a Gram negative rod, motile by means of a single polar flagellum.
- They are pleomorphic Gram negative bacilli, motile by peritrichious flagella.
205
What is the habitat of Pseudomonos and Proteus respectively?
- Aeruginosa opportunistic pathogen
- Inhabits soil, sewage & water Some are commensals in intestine
- Opportunistic pathogen& Found in soil, air.
- Human intestinal flora.
206
What is the diseases of Pseudomonos and Proteus respectively?
1- Urinary tract infections (UTI)
2- Bacteremia
3- Respiratory system infections
4- Systemic infections in patients with
severe burns & in cancer & AIDS patients.
1- Cystitis (UTI)
2- Pyelonephritis
3- Otitis media
207
What is the culture of Pseudomonos and Proteus respectively?
A- Requirements:
O2: Obligate aerobic
TEMP: Grow at 42°C with specific fruity odor
"The burned tissue smells like fruit"
B- Media:
- Grows well on most laboratory media Producing two types of exopigments
1-Pyoverdin: Fluorescent pigment
2-Pyocyanin: Blue pigment
A- Requirements:
O2: Facultative anaerobes
B- Media:
- Simple media > swarm across the surface of agar plates.
- MacConeky's agar-> Pale yellow colonies
(non-lactose fermenter)
C- Serological characters:
- Proteus OX19, proteus OXK, OX2 share antigens with Ricketssiae & are used in serodiagnosis of rickettsial infections in the Weil Felix agglutination test.
208
What is the biochemical reactions of Pseudomonos and Proteus respectively?
- Ferment no sugar. "Yellow in mcconkey"
- Oxidase positive
- H2S positive
- Urease positive
209
What is the site of Streptococcus faecalis (enterococci)?
- Present in GIT.
- Indication of fecal pollution of water.
210
What does streptococcus faecalis cause?
- Urinary tract.
- Wound infections
211
What is the biochemical reaction done to diagnose Streptococcus faecalis?
- Positive for bile esculin hydrolysis.
- Bacteria are able to grow in the presence of bile salts & the hydrolysis of the esculin in the medium results in the formation of glucose & esculetin, Esculetin reacts with ferric ions (supplied by ferric citrate) to form a black
diffusible complex
212
What are the steps for diagnosis of urinary tract infections?
- Specimen collection
- pecimen transportation
- Direct with film examination new film
- Smears are done to the urine deposit after ZN stain
- Bacteriological examination
- Reporting bacterial number
- Antibiotic sensitivity testing
213
What are types of specimens collected in diagnosis of UTI?
- Mid-stream specimen
- Catheter
214
What is the method of collection of midstream urine in both male and female and where is it collected?
- Collected in universal containers.
- In male the external urethral meatus is cleaned before taking the midstream sample.
- In female: repeated vaginal washing is recommended & the midstream sample is taken after separating the labia.
215
How is urine intake from the catheter and what technique should be applied?
- Catheterization may introduce infection even under ideal conditions.
- Taken from the catheter itself, not from urine bag.
- Complete aseptic technique using a sterile syringe & needle through the "collection after its wiping with an alcohol-soaked cotton"
216
How should TB sample be collected in case of UTI and what are its disadvantages?
- 3 successive days is the most suitable specimen & acid & alcohol fast "see Respiratory"
- But Low sensitive: high number of tubercle bacilli is required
217
How is specimen transportation done?
- Rapid transport of urine samples is important.
- Samples can be stored for 24 hours at 4°c or addition of boric acid.
218
Why is direct with film examination done?
- For pus cells count (per high power field).
219
Why are smears from urine deposit after ZN Stain checked?
- In suspected cases of tuberculosis to reveal the morphological characters of the organism.
220
How is bacteriological examination done for UTI infections?
Bacteriological examination:
- Culture: on CLED medium
- Colony identification by Gram stained film.
- Biochemical reactions: the reaction of the isolated organism on CLED medium (LF/NLF).
221
What does 100,000/Ml of bacteria indicate?
- Count the approximate number of colonies.
- More than 100 000/ml, significant bacteriuria.
