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Medical Microbiology > 2SCT > Flashcards

2SCT Flashcards

1
Q

Mention four E. coli pathogenetic groups involved in enteric diseases!

A

Enteropathogenic E. coli (EPEC)
Enterotoxic E. coli (ETEC)
Enteroinvasive E. coli (EIEC)
Enterohemorrhagic E. coli (EHEC) Enteroaggregative E. coli (EAggEC)

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2
Q

What are the most important extraintestinal infections caused by E. coli? Mention at least 3 of them!

A

urinary tract infections, neonatal meningitis, nosocomial wound infections

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3
Q

The most frequent causative agent of urinary tract infections is:

A

Escherichia coli

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4
Q

Which 2 diseases are caused by E. coli O157:H7?

A

hemorrhagic colitis +/- HUS (hemolytic uraemic syndrome)

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5
Q

What is the reservoir of Salmonella typhi?

A

humans (with disease, or healthy carriers)

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6
Q

Which bacteria cause most frequently typhoid fever and enteric fever, respectively?

A

Salmonella typhi (typhoid)
Salmonella paratyphi A, B, C (enteric fever)

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7
Q

When typhoid fever is suspected, what kinds of clinical samples should be used to isolate the causative agent in the first 2 weeks of the disease?

A

Blood, (bone marrow)

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8
Q

What is the route of infection in Salmonella gastroenteritis?

A

Ingestion of contaminated food (such as eggs, cream, mayonnaise, creamed foods, etc.) containing a sufficient number of Salmonella.

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9
Q

Which antibacterial drugs should be administered in gastroenteritis caused by Salmonella?

A

Antibiotics are usually contraindicated unless the infection is generalised. In case of extraintestinal infection (very young, very old or immunosuppressed patients): ampicillin, gentamicin, trimethoprim/sulfamethoxazole, third generation cephalosporins, or ciprofloxacin.

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10
Q

List the 4 Shigella species causing human disease!

A

Shigella dysenteriae, S. flexneri, S. boydii, S. sonnei

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11
Q

Mention 2 bacterial species belonging to different genera that cause bacillary dysentery

A

Shigella dysenteriae, (Shigella flexneri, Shigella boydii, Shigella sonnei), enteroinvasive E. coli (EIEC)

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12
Q

Mention 3 bacterial species belonging to different genera that cause enteritis or enterocolitis!

A

Campylobacter jejuni, Escherichia coli, Salmonella enteritidis, Shigella, Yersinia enterocolitica

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13
Q

What are the modes of transmission for the 2 different epidemiologic forms of plague?

A
  • Bubonic plague is transmitted by the bite of infected rat fleas from rats to humans.
  • Primary pneumonic plague spreads directly from human to human via respiratory droplets.
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14
Q

What are the possible portals of entry of Francisella tularensis? Specify at least 4!

A

tick bite, conjunctiva, skin abrasions, resp. tract, gastroint. tract

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15
Q

How do humans acquire brucellosis? Where do the bacteria replicate in the human body?

A

Via contaminated milk products or through skin abrasions (contact with animals). Organisms spread to the mononuclear phagocytes of the reticuloendothelial system (lymph nodes, liver, spleen, bone marrow).

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16
Q

What are the reservoirs of the different Brucella species, respectively?

A

B. abortus: cattle
B. melitensis: goat, sheep B. suis: swine
(B. canis: dog)

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17
Q

What is the mechanism of action of cholera toxin?

A

Cholera toxin activates the adenylate cyclase enzyme in cells of the intestinal mucosa leading to increased levels of intracellular cAMP, and the secretion of large amount of water, Na+, K+, Cl-, and HCO3- into the lumen of the small intestine.

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18
Q

What is the principle of the treatment for cholera?

A

Rapid intravenous or oral replacement of the lost fluid and ions. In severe cases: administration of tetracycline (in addition to rehydration).

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19
Q

Mention 4 diseases caused by Haemophilus influenzae!

A

purulent meningitis
epiglottitis (obstructive laryngitis)
otitis media and sinusitis
pneumonia
(cellulitis, arthritis)

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20
Q

Which disease is caused by Haemophilus ducreyi?

A

Chancroid (soft chancre or ulcus molle), which is an STD (sexually transmitted disease)

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21
Q

Mention 4 diseases that are frequently caused by Pseudomonas aeruginosa!

A

urinary tract infections, wound infections (burns), otitis externa, pneumonia, sepsis (immunosupression)

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22
Q

Mention at least 3 drugs which may be effective to treat infections caused by Pseudomonas aeruginosa!

A

certain penicillins: piperacillin/tazobactam combination
a 3rd generation cephalosporin: ceftazidim
a 4th generation cephalosporin: cefepime certain aminoglycosides: gentamycin, amikacin carbapenems: imipenem, meropenem

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23
Q

What are the frequent sources of infection for Legionella pneumophila?

A

air conditioners, water taps, showers, evaporators, etc.

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24
Q

Which 2 diseases are caused by Legionella pneumophila?

A
  • legionellosis, legionnairs’ disease (atypical pneumonia) - Pontiac fever (mild, flu like illness without pneumonia)
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25
Q

List 3 important virulence factors of Bordetella pertussis!

A

pertussis toxin, filamentous hemagglutinin, adenylate-cyclase toxin, tracheal cytotoxin

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26
Q

What is the precise definition of bacterial food poisoning?

A

Acute disease, usually with vomiting and diarrhea, usually caused by preformed toxins produced by bacteria contaminating the food. The period between consumption of food and the appearance of symptoms is short (< 4-6 hours).

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27
Q

Mention 3 bacterium species causing food poisoning!

A

Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Clostridium botulinum

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28
Q

Which bacterium has the highest germ number in the colon?

A

Bacteroides fragilis

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29
Q

Mention 4 bacterial genera that are obligate anaerobes!

A

Clostridium, Bacteroides, Prevotella, Porphyromonas, Fusobacterium, Actinomyces, Bifidobacterium, Peptostreptococcus, Propionibacterium

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30
Q

Which is the most important gas gangrene Clostridium? What is its main virulence factor?

A

Clostridium perfringens
alpha-toxin (lecithinase)

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31
Q

Mention 3 Clostridium species causing gas gangrene! How are they acquired?

A

Clostridium perfringens, C. novyi, C. septicum, C. histolyticum, C. tertium, C. bifermentans, C. sporogenes
The site of infection is usually a wound that comes into contact with Clostridium spores that germinate in an anaerobic environment.

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32
Q

How can be tetanus prevented in patients who have wounds possibly contaminated with C. tetani spores?

A

tetanus injection,
tetanus immunoglobulin (TETIG) in previously unvaccinated patients

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33
Q

What are the main symptoms of tetanus? Specify at least 3!

A

Spastic paralysis: muscle spasms; respiratory paralysis

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34
Q

What is the mechanism of action of botulinum toxin?

A

Blocks release of acetylcholine in peripheral nerve synapses;

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35
Q

What are the main symptoms of botulism? Specify at least 3!

A

diplopia (double vision), dysphagia (difficulty to swallow), dysphonia,

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36
Q

What kind of therapy is used to treat botulism?

A

Treatment: respiratory support + trivalent antitoxin

37
Q

Explain whether or not antibiotic treatment is useful in botulism!

A

Not, because antibiotics are not effective against preformed toxins.

38
Q

Mention at least 2 drugs that can be used to treat diseases caused by Clostridioides difficile!

A

vancomycin, metronidazole, fidaxomicin

39
Q

What diseases may be associated with Helicobacter pylori? Specify at least 3!

A

Gastritis, peptic and duodenal ulcers, gastric carcinoma, MALT lymphoma

40
Q

What is the most important virulence factor of Corynebacterium diphtheriae?

A

Diphtheria toxin

41
Q

What is the mechanism of action of the diphtheria toxin?

A

Inhibits protein synthesis. Inhibits peptide elongation in eukaryotic ribosomes by ADP ribosylation of EF-2 (elongation factor-2)

42
Q

How long does immunity against diphtheria exist?

A

Which immune effector mechanism is involved?
long lasting immunity; antitoxic antibodies

43
Q

Which assays must be performed in the laboratory diagnosis of diphtheria?

A

Smears of the throat swab should be stained with methylene blue or Neisser stain; bacteria are cultured on Löffler’s or tellurite (Clauberg) medium; toxin production must be demonstrated by agar precipitation ( ELEK-test)

44
Q

What are the 2 main forms of leprosy?

A

Tuberculoid (paucibacillary) or lepromatous (multibacillary) form

45
Q

Mention 3 Gram-negative bacteria belonging to different genera causing zoonosis!

A

Brucella, Francisella tularensis, Yersinia pestis, Pasteurella

46
Q

Mention 2 Gram-positive bacteria belonging to different genera causing zoonosis!

A

listeria monocytogenes, Bacillus anthracis, Erysipelothrix rhusiopathiae

47
Q

Mention 3 bacterial species belonging to different genera that are frequent causes of urinary tract infections!

A

E. coli, Klebsiella, Pseudomonas aeruginosa

48
Q

Mention one aerobic and one anaerobic bacterium of the normal flora of the skin!

A

aerobic: Staphylococcus epidermidis

anaerobic: Cutibacterium (Propionibacterium) acnes

49
Q

Give two genera for each category of bacteria!

Gram positive aerobic:

Gram positive anaerobic:

A

Staphylococcus, Streptococcus, Bacillus, Corynebacterium

Clostridium, Actinomyces, Propionibacterium

50
Q

Give two genera for each category of bacteria!

Gram negativ aerobic:

Gram negativ anaerobic:

A

Vibrio, Neisseria, Haemophilus

Bacteroides, Prevotella, Porphyromonas, Veillonella

51
Q

Give 2 genera for each category of bacteria!

Gram positive coccus:

Gram negative coccus:

Gram positive rod:

A

Staphylococcus, Streptococcus

Neisseria, Veillonella

Clostridium, Bacillus

52
Q

Give 2 genera for each category of bacteria!

Gram negative rod:

Spirochetes:

A

E. coli, Salmonella, Shigella

Treponema, Borrelia, Leptospira

53
Q

Describe the color and the shape of Clostridia in a Gram stained smear of gas gangrene exudate!

A

Gram positive (dark blue) rod
(it usually does not form spores in vivo)

54
Q

Mention 2 antibiotics which can be used in the empirical treatment against Gram negative obligate anaerobic bacteria!

A

Metronidazol, amoxicillin + clavulanic acid

55
Q

Which 3 bacterial species are the most important causative agents of neonatal (< 1 month of age) meningitis?

A

Streptococcus agalactiae, E. coli, Listeria monocytogenes

56
Q

Which 3 bacterial species are the most important causative agents of meningitis among babies (> 1 month of age) and children?

A

Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae

57
Q

What is the empirical antibiotic therapy of bacterial meningitis?

A

ceftriaxone / cefotaxime

58
Q

What is the causative agent of febris undulans (undulant fever)?

A

Brucellae

59
Q

What are the main manifestations in early (primary and secondary) syphilis?

A

Primary syphilis: nontender ulcer (hard chancre)

Secondary lesions: maculopapular rash on skin, and condylomata lata on mucous membranes

60
Q

What are the main manifestations in late (tertiary) syphilis?

A

Granulomas

61
Q

When syphilis is diagnosed in the laboratory, which antigens are used in the non- treponemal and in the specific treponemal antibody tests, respectively?

A

Non-treponemal antibody tests: cardiolipin
Specific treponemal antibody tests: antigens originating from Treponema pallidum or whole bacterial cells of Treponema pallidum

62
Q

Which are the two different groups of serological tests used in the diagnosis of syphilis? Give 2 examples for both groups of tests!

A

Non-treponemal tests: RPR, VDRL
Specific treponemal tests: ELISA, Western blot

63
Q

What is the advantage and disadvantage of the specific (treponemal) syphilis serologic tests compared to the nonspecific (nontreponemal) test?

A

Specific (treponemal) tests are more specific than the nontreponemal tests, but they can not be used to follow the efficacy of treatment (because the specific antibodies persist even after effective eradication of bacteria).

64
Q

What is the drug of first choice in the treatment of syphilis?

A

penicillin G

65
Q

What is the reservoir and what is the vector for Borrelia recurrentis?

A

Reservoir: human; vector: louse

66
Q

What is used for the laboratory diagnosis of relapsing fever?

A

Direct demonstration of bacteria from peripheral blood smear by microscopy (Giemsa stain or dark field illumination)

67
Q

What is the causative agent of Lyme disease?

A

Borrelia burgdorferi

68
Q

Mention 2 antibacterial drugs that are of first choice in early stage Lyme disease!

A

Doxycycline, amoxicillin

69
Q

What is the first characteristic manifestation in the early phase of Lyme disease?

A

Erythema (chronicum) migrans

70
Q

Which manifestations are characteristic for the late phases of Lyme disease?

A

Arthritis, cardiac manifestations (myocarditis, pericarditis) and neurological involvement (meningitis, peripheral neuropathies)

71
Q

What is the reservoir of Leptospira interrogans?

A

rodents, household animals (dog, swine etc.)

72
Q

Mention 2 obligate intracellular bacterial genuses!

A

Rickettsia, Chlamydia, (Coxiella, Ehrlichia)

73
Q

Mention 4 bacteria causing atypical pneumonia!

A

Chlamydia pneumoniae
Chlamydia psittaci
Mycoplasma pneumonia
Legionella pneumophila

74
Q

Which two diseases are caused by Rickettsia prowazekii?

A

Louse-borne epidemic typhus
Recurrent form: Brill-Zinsser disease

75
Q

Mention an antibacterial drug active against rickettsial infections!

A

Tetracycline

76
Q

What is the reservoir and the vector of Rickettsia prowazekii infections?

A

reservoir: human; vector: louse

77
Q

What is the reservoir and the vector of Rickettsia typhi infections?

A

reservoir: rodents; vector: flea

78
Q

What is the causative agent of epidemic typhus?

A

Rickettsia prowazekii

79
Q

What is the causative agent of endemic typhus?

A

Rickettsia typhi

80
Q

How can be Chlamydiae and Rickettsiae cultivated?

A

These are obligate intracellular bacteria, can be cultured in experimental animals, embryonated eggs, and cell culture

81
Q

Mention an antibacterial drug active against chlamydial infections!

A

Tetracycline

82
Q

List the serotypes of Chlamydia trachomatis and the diseases caused by them!

A

Types A, B and C: trachoma (chronic conjunctivitis)
Types D-K: genital tract infections (NGU, PID), inclusion conjunctivitis
Types L1-L3: lymphogranuloma venereum (STD)

83
Q

Mention an antibacterial drug effective against Mycoplasma pneumoniae infections!

A

tetracycline

84
Q

Why are penicillins not effective against Mycoplasma pneumoniae infections?

A

Because of the absence of a cell wall, penicillins are ineffective (penicillins inhibit cell wall synthesis)

85
Q

Mention 4 bacteria frequently causing sexually transmitted diseases (STD)!

A

Treponema pallidum, Neisseria gonorrhoeae, Haemophilus ducreyi, Chlamydia trachomatis, (Calymmatobacterium granulomatis)

86
Q

Which bacterial species can cause hepatitis (jaundice)?

A

Leptospira interrogans

87
Q

Mention 2 bacteria causing aseptic (serous) meningitis!

A

Treponema pallidum, Leptospira interrogans

88
Q

Mention a bacterial pathogen which eludes the host immune response by frequent antigenic changes!

A

Borrelia recurrentis

89
Q

What is the causative agent of febris recurrens (recurrent fever)?

A

Borrelia recurrentis

Medical Microbiology (3 decks)

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