Flashcards in *Microbiology 2 (Lecture 2) Deck (77)
What are the causes of the classical flu?
Influenza A virus
Influenza B virus
What is the cause of a flu like illness?
Parainfluenza viruses but many other causes
Does haemophilus influenzae cause flu?
Not a primary cause (it is a bacterium) but may be a secondary invader
Complications of flu?
Primary influenzal pneumonia
Secondary bacterial pneumonia
Influenza during pregnancy may also be associated with perinatal mortality, prematurity, smaller neonatal size and lower birth weight
How is flu treated?
Symptomatic (bed rest, fluids, paracetamol)
Antivirals (only if patient is at risk of complications and when flu is circulating and early in disease)
What antivirals are used to treat flu?
What are epidemics of flu associated with?
Minor mutations in the surface proteins of the virus (antigenic drift)
What is the difference between epidemic and pandemic?
An epidemic occurs when a disease affects a greater number people than is usual for the locality or one that spreads to areas not usually associated with the disease. A pandemic is an epidemic of world-wide proportions.
What type of flu can cause pandemics?
Influenza A only
What subtype of influenza A is avian flu?
How is influenza confirmed in the lab?
Direct detection of virus:
PCR (nasopharyngeal swab, throat swab or other respiratory samples)
Other labs/ hospitals may used immunofluorescence, antigen detection (near patient)
Prevention of flu?
Killed vaccine (given to adult/ child (aged 6 months to 2 years) patients at high risk and healthy care workers)
Live attenuated vaccine (more effective than killed vaccine in children aged 2-17, given to ALL children aged 2-5 and all primary school children administer intra-nasally)
When are antivirals used as a prophylaxis against flu?
After a contact with flu
What are 3 examples of atypical pneumonia?
How are these treated?
Coxiella and Chlamydohila psittaci
Tetracycline and macrocodes e.g. clarithromycin
Mortality of atypical pneumonias?
Varies with pathogen by generally lower than classical bacterial pneumonia
How are the atypical pneumonias (mycoplasma, coxiella, psittaci) diagnosed?
By serology (send acute and convalescent bloods to lab)
Virus detection (PCR on respiratory swabs/ secretions)
Who tends to get mycoplasma pneumoniae?
Children and young adults
Person to person spread
What diseases does coxiella burnetti cause?
what is infection with coxiella burnetti associated with?
Sheep and goats
Complications of infection wit coxiella burnetti?
Culture negative endocarditis
What illness does infection with chlamoydophila psittaci cause?
How does this usually present?
Psittacosis (parrot fever)
What age do patients present with bronchiolitis?
1st or 2nd year of life
Severe cases can cause grunting, decreased PaO2, intercostal/ sternal indrawing
Complications of bronchiolitis?
Respiratory and cardiac failure
(especially if premature or pre-existing conditions)
What is usually the cause of Bronchiolitis?
How is this confirmed?
Respiratory Syncytial Virus
By PCR on throat or perusal swab
Therapy for bronchiolitis?
What is metapneumovirus?
A respiratory viral pathogen that causes acute respiratory tract infection in children
Most children have antibody by age 5
What diseases does metapneumovirus cause?
Second only to RSV in bronchiolitis
2% of cases pf influenza-like illness
Ranges in severity from mild to requiring ventilation
How is metapneumovirus confirmed in the lab?
what is a cause of infantile pneumonia related to an STI?
How is it diagnosed?
PCR on urine of mother or perusal/ throat swabs of child
What does chlamoydophila pneumonias cause?
Mostly mild respiratory infeciton
Person to person spread
What is the upper respiratory tract colonised with?
Alpha-haemolytic streptococci inc. strep pneumoniae
B-haemolytic streptococci inc. strep pyogenes
What are the 5 types of upper respiratory tract infections
Pharyngitis (includes pharynx, tonsils and uvula)
What usually causes epiglottitis/
Haemophilus influenzae type B
Clinical picture of epiglottitis?
Acute onset (hours)
sevre croup/ stridor
Adult onset is days
How do we test for epiglottitis?
Why do we not test for epiglottis using a throat swab?
It can irritate the epiglottis further causing it to swell up further
Treatment for epiglottis?
Usually admitted to ICU and treated with Ceftriaxone
Are the conducting airways (trachea and bronchi) usually colonised?
When do patients tends to get infection in their conducting airways (trachea and bronchi)?
Changes to airway e.g. trauma/ intubation
What are the pathogenic causes of acute COPD exacerbation?
Can be environmental
Why do patients with CF tend to get frequent infections?
Inefficient clearance and build-up of mucus
What types of bacteria are often seen in CF patients?
Staph aureus. haemophilus influenzae, strep pneumoniae, pseudomonas aeruginosa, Burkholderia cepacia and MANY others
What is whooping cough (pertussis)?
What are the clinical features of whopping cough (pertussis)
Cold like symptoms for 2 weeks
Repeated voilent exhalations with severe inspiratory whoop, vomiting common
Residual cough for month or more
What bacteria causes whooping cough?
Bordetella pertussis (gram negative coccobacillus)
How is pertussis diagnosed?
Bacterial culture (pernasal swab)
PCR (pernasal swab)
Treatment of pertussis?
Antibiotics if had cough for less than 21 days - clarithromycin (erythromycin if pregnant)
Clinical features of CAP?
CXR with infiltrates
Acquired in the community
Is legionella gram negative or gram positive?
Clinical features of legionella pneumonia?
Flu like illness which may progress to severe pneumonia, with mental confusion, acute renal failure and GI symptoms
How is legionella pneumonia spread?
No person to person spread
Inhalation of contaminated water droplets
Therefore associated with shower heads, cooling towers, air conditioning
Diagnosis of legionella pneumonia?
Legionella urinary antigen (detects serogroup 1 only)
PCR available direct from sputum
Treatment of legionella pneumonia?
Clarythromycin, erythromycin, levofloxacin
What is the greatest risk for developing hospital acquired pneumonia?
Endotracheal intubation with mechanical ventilation (also risks with sedation, micro aspirations, aspirations of GI contents, immunosuppression)
Microbiology of HAP?
60% = gram negative including E. coli, Klebsiella spp, pseudomonas app, CAP organisms, S aureus and anaerobes
Treatment of a severe HAP?
IV amoxicillin, metronidazole and gentamicin
Step down to PO co-trimoxazole + metronidazole
Treatment of non-severe HAP?
PO amoxicillin + metronidazole
What is the full name of PCP?
Pneumocystis jirovecii pneumonia
What type of patients get this?
One of the most frequent and severe opportunistic infection in people with weakened immune systems e.g. aIDS, immunosuppression (people with a normal immune system can be asymptomatic with it either carrying it or eradication it)
What type of organism is pneumocystitis jirovecii?
Does mycoplasma pneumonia cause a dry or wet cough?
Symptoms of PCP?
HIV patients = sub-acute, low grade fever, severe pneumonia
Non-HIV = more acute high fever
Diagnosis of PCP?
Microscopy (immunofluorescence of gargle)
Treatment of PCP?
Co-trimoxazole or pentamdine
What are a list of causes of CAP?
Streptococcus pneumonia (Common)
Haemophilus pneumoniae (common)
Moraxella catarrhalis (common)
Mycoplasma pneumonie (common, atypical)
Chlamydias (pneumoniae (atypical), psiticci (atypical), trachomatis)
Legionella pneumoniae (atypical)
Coxiella burnetti (atypical)
Aside from PCP, what is another fungal chest infection?
What causes aspergilus chest infection?
Usually aspergillum fumigates (common environmental fungus)
What type of patients get aspergillus chest infection?
Immunocompromised/ supressed patients
(causes severe pneumonia and invasive disease)
What type of infection do immunocompetent patients infected by aspergillus get?
Localised pulmonary infection
Aspergilloma (fungus ball) in pre-existing chest caivties
How is aspergillus diagnosed?
Bronchoalveolar lavage ideally (fungal culture, PCR)
Treatment of aspergillus?
Causes of TB?
Appearance of TB?
Acid alcohol fast bacilli with a thick waxy coat
Pathogensis of TB?
Mycobacterium tuberculosis are engulfed by alveolar macrophages in alveoli but resist killing and multiply leading to a focus
Types of TB?
90% asymptomatic and develop latent TB (alterations in immune function leads to reactivation and active TB)
10% develop immediate active TB
Clinical symptoms of TB?
Long term cough
Sputum =?- haemoptysis
Weakness or fatigue
Fever and chills
Diagnosis of TB?
Microscopy of sputum/ tissue
Culture on selective media