Micro - Bacteriology (Part 2) Flashcards Preview

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Flashcards in Micro - Bacteriology (Part 2) Deck (103)
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1
Q

A patient presents with septic shock and has the blood cultures shown here. What organism is this? What other organs should you worry about?

A

Staphylococcus aureus; bone and heart; S. aureus causes osteomyelitis and acute bacterial endocarditis

2
Q

A patient is found to have this histologic finding on biopsy of an upper lobe lesion. What is the most likely medical history?

A

An adult reinfected with tuberculosis

3
Q

All mycobacteria have what staining property seen in this image?

A

They are all acid-fast

4
Q

What bacteria causes syphilis?

A

Treponema pallidum

5
Q

Treponema pertenue causes what condition?

A

Yaws

6
Q

What tropical infection is not a sexually transmitted disease but results in a positive venereal disease research laboratory test?

A

Yaws

7
Q

What are the symptoms commonly associated with yaws?

A

Joint deformities following keloid healing of skin, bone and joint infection

8
Q

First-degree syphilis presents with what type of lesion?

A

A painless chancre at the site of infection (localized disease)

9
Q

Is second-degree syphilis a localized or disseminated disease?

A

Disseminated (remember: Secondary syphilis = Systemic)

10
Q

Second-degree syphilis presents with what type of skin manifestations?

A

A maculopapular rash on palms and soles and condylomata lata

11
Q

Third-degree syphilis presents with what signs and symptoms?

A

Gummas, aortitis, tabes dorsalis, and Argyll Robertson pupil

12
Q

Which stage of syphilis is characterized by broad-based ataxia, a positive Romberg sign, Charcot joints, and stroke-like symptoms?

A

Third-degree syphilis

13
Q

Third-degree syphilis can present with what neurologic defects?

A

Tabes dorsalis (resulting in broad-based gait, ataxia, and positive Romberg test) and Argyll Robertson pupil

14
Q

What signs and symptoms are associated with congenital syphilis?

A

Saber shins, saddle-nose deformity, neurological (cranial nerve VIII) deafness, Hutchinsons teeth, and mulberry molars

15
Q

What is the treatment of choice for syphilis?

A

Penicillin G

16
Q

Where can treponemes be found during primary and secondary syphilis?

A

In chancres during primary syphilis and in condylomata lata during secondary syphilis

17
Q

What causes aortitis in tertiary syphilis?

A

Destruction of the vasa vasorum

18
Q

Argyll Robertson pupil is associated with what disease?

A

Tertiary syphilis

19
Q

Describe the findings in a patient with an Argyll Robertson pupil.

A

Pupil dilation with accommodation but not with direct light

20
Q

Which diagnostic test is most specific for treponemes, turns positive earliest during the course of disease, and remains positive for the longest time?

A

Fluorescent treponemal antibody absorption test (remember: FTA-ABS = Find The Antibody-ABSolutely)

21
Q

A positive venereal disease research laboratory test and a positive fluorescent treponemal antibody absorption test indicate what?

A

Active infection with a treponeme that causes syphilis

22
Q

If a venereal disease research laboratory test is positive but the fluorescent treponemal antibody absorption test is negative, what is the interpretation?

A

False-positive result for syphilis infection

23
Q

What do negative venereal disease research laboratory test and positive fluorescent treponemal antibody absorption test results indicate?

A

Successful treatment of syphilis

24
Q

Which conditions give biologic false-positive results for the venereal disease research laboratory test?

A

Viral infection, drugs, rheumatic fever, rheumatoid arthritis, systemic lupus erythematosus, and leprosy. (remember: VDRL = Viruses, Drugs, Rheumatic fever and arthritis, Lupus and leprosy)

25
Q

A positive venereal disease research laboratory indicates that antibodies have formed against what molecule?

A

Beef cardiolipin

26
Q

Name six medically important zoonotic bacteria.

A

Bartonella henselae, Borrelia burgdorferi, Brucella spp, Francisella tularensis, Yersinia pestis, and Pasteurella multocida, Ella (remember: Big Bad Bugs From Your Pet named Ella)

27
Q

What organism transmitted by dairy products and contact with animals causes undulant fever?

A

Brucella spp (remember: Unpasteurized dairy products give you Undulant fever)

28
Q

A dairy farmer presents with one week of fever that waxes and wanes without treatment. What is the diagnosis?

A

Brucella spp, which are found in dairy products or transmitted via contact with cows, sheep, and goats

29
Q

How is Francisella tularensis transmitted?

A

Tick bites

30
Q

What organism causes tularemia?

A

Francisella tularensis

31
Q

Name two animal reservoirs for ticks that transmit Francisella tularensis.

A

Rabbits and deer

32
Q

Which organism causes the plague?

A

Yersinia pestis

33
Q

What is the mode of transmission of the bubonic plague?

A

Flea bites

34
Q

What is the animal reservoir for ticks transmitting Yersinia pestis?

A

Rodents (especially prairie dogs)

35
Q

How is Pasteurella multocida transmitted?

A

Animal bite (cats, dogs)

36
Q

What infection is caused by Pasteurella multocida?

A

Cellulitis after cat and dog bites

37
Q

What is the disease caused by Bartonella?

A

Cat scratch fever

38
Q

What dermatologic finding can Bartonella cause in immunocompromised individuals?

A

Bacillary angiomatosis (can be mistaken for Kaposi sarcoma)

39
Q

What is the most common mode of transmission for the bacteria Bartonella henselae?

A

Cat scratch

40
Q

What kind of discharge is produced in vaginosis caused by Gardnerella vaginalis?

A

Off-white/gray vaginal discharge, fishy odor

41
Q

What is the treatment of choice for vaginosis caused by Gardnerella vaginalis?

A

Metronidazole

42
Q

What kind of cells (seen on a wet mount of vaginal discharge) are diagnostic of infection with Gardnerella vaginalis?

A

Clue cells (vaginal epithelial cells covered with bacteria)

43
Q

What are clue cells?

A

Vaginal epithelial cells covered with bacteria to the point where intracellular organelles are obscured

44
Q

Is Gardnerella vaginalis considered a sexually transmitted disease?

A

No, it is not a sexually transmitted disease, although it is more common in sexually active women

45
Q

What anaerobic bacteria other than Gardnerella vaginalis is frequently involved in vaginosis?

A

Mobiluncus

46
Q

A women presents with fishy gray vaginal discharge. What is the likely diagnosis and what will you prescribe?

A

Bacterial vaginosis caused by Gardnerella; treatment with metronidizole

47
Q

True or False? Rickettsiae are facultative intracellular parasites.

A

False; Rickettsiae are obligate intracellular parasites

48
Q

Rickettsiae are obligate intracellular parasites because they require which two cofactors?

A

Coenzyme A and nicotinamide adenine dinucleotide

49
Q

Rickettsiae are obligate intracellular parasites that are transmitted by what type of vector?

A

Arthropods (except Coxiella, which is transmitted by aerosol)

50
Q

Why is Coxiella considered an atypical rickettsia?

A

Because it causes pneumonia, instead of the classic triad of fever, headache, and rash, and it is the only one not carried by an arthropod vector

51
Q

What is the classic triad of symptoms caused by a rickettsial infection?

A

Fever, headache, and rash (vasculitis)

52
Q

What disease does Rickettsia rickettsii cause?

A

Rocky Mountain spotted fever

53
Q

The pathogen that causes Rocky Mountain spotted fever is carried by what vector?

A

Ticks

54
Q

Endemic typhus is caused by what bacterium?

A

Rickettsia typhi

55
Q

The pathogen that causes endemic typhus is carried by what vector?

A

Fleas

56
Q

Epidemic typhus is caused by what bacterium?

A

Rickettsia prowazekii

57
Q

The pathogen that causes epidemic typhus is carried by what vector?

A

Human body lice

58
Q

Q fever is caused by what bacterium?

A

Coxiella burnetii

59
Q

The pathogen that causes Q fever is carried by what vector?

A

Coxiella burnetii is an atypical Rickettsia in that it has no vector and is transmitted via aerosol

60
Q

What is the treatment of choice for all Rickettsial infections?

A

Tetracycline

61
Q

How could one distinguish between the rash of Rocky Mountain spotted fever and that of typhus?

A

Rocky Mountain spotted fever starts in the periphery and moves inward whereas typhus starts in the trunk and moves outward (remember: Rickettsia on the wRists, Typhus on the Trunk)

62
Q

Which rickettsial disease does not present with a rash?

A

Q fever is the only rickettsial infection that does not cause a rash

63
Q

Does Q fever have a positive or negative Weil-Felix reaction assay?

A

Negative; a Weil-Felix assay is usually positive for typhus and Rocky Mountain spotted fever but negative for Q fever

64
Q

True or False? Coxiella burnetii can survive outside of the body for a long time.

A

True; Coxiella burnetii is the only rickettsial pathogen that can survive outside the body for long periods of time

65
Q

Ehrlichia is carried by what type of vector?

A

Tick

66
Q

A child who was recently camping in Virginia presents with a rash moving up the arms and legs, headache, fever, and a very ill appearance. What is your diagnosis and how will you treat?

A

Rocky Mountain spotted fever; treatment with tetracycline

67
Q

Rocky Mountain spotted fever is endemic to what area?

A

The East Coast; despite its name it is not seen in the Rocky Mountains

68
Q

What three diseases start with a rash on the palms and soles?

A

Coxsackievirus A (hand-foot-and-mouth disease), Rocky Mountain spotted fever, and Syphilis (remember: you drive CARS with your palms and soles)

69
Q

The Weil-Felix reaction is used to test for what pathogens?

A

Rickettsiae (this reaction is an assay for antibodies)

70
Q

In a Weil-Felix reaction, antirickettsial antibodies in patient serum cross-react and agglutinate when mixed with antigens from what pathogen?

A

Proteus

71
Q

Which rickettsial infection will have a negative Weil-Felix reaction?

A

Coxiella burnetii (which causes Q fever)

72
Q

What are the two forms of Chlamydiae?

A

The elementary body and the reticulate body

73
Q

During their life cycle, what form of chlamydia is infectious (ie, enters host cells)?

A

The Elementary body (small, dense) Enters the body via Endocytosis

74
Q

During their life cycle, what form of chlamydia replicates by fission?

A

The Reticulate (initial) body Replicates in the cell by fission

75
Q

What diseases are caused by Chlamydia trachomatis?

A

Reactive arthritis, conjunctivitis, nongonococcal urethritis, cervicitis, and pelvic inflammatory disease

76
Q

Which two chlamydial species cause atypical pneumonia and how are they transmitted?

A

Chlamydia pneumoniae and Chlamydia psittaci; both are transmitted by aerosol

77
Q

Chlamydia psittaci has what animal reservoir?

A

Birds

78
Q

What are the treatments of choice for chlamydial infections?

A

Erythromycin or tetracycline

79
Q

How can chlamydial infection be diagnosed by microscopy?

A

By cytoplasmic inclusions seen on Giemsa or fluorescent antibody staining

80
Q

The chlamydial cell wall is unique in that is lacks _____ _____.

A

Muramic acid

81
Q

Why are Chlamydia intracellular organisms?

A

Because they cannot make their own adenosine triphosphate

82
Q

Which Chlamydia trachomatis serotypes cause chronic infection and blindness in Africa?

A

Types A, B, and C (remember: Africa, Blindness, Chronic infection)

83
Q

Which Chlamydia trachomatis serotypes cause urethritis, pelvic inflammatory disease, ectopic pregnancy, neonatal pneumonia, and neonatal conjunctivitis?

A

Types D through K

84
Q

Which Chlamydia trachomatis serotypes cause lymphogranuloma venereum?

A

Types L1, L2, and L3 (remember: Lymphogranuloma)

85
Q

What is the treatment of choice for neonatal disease caused by Chlamydia trachomatis?

A

Oral erythromycin

86
Q

What test is positive in lymphogranuloma venereum?

A

Frei test

87
Q

When is neonatal Chlamydia acquired?

A

As the infant passes through an infected birth canal

88
Q

What are the symptoms of lymphogranuloma venereum?

A

Acute lymphadenitis

89
Q

What other infection has similar symptoms to lymphogranuloma venereum?

A

Granuloma inguinale (donovanosis) caused by Calymmatobacterium granulomatis

90
Q

What bacteria is most commonly implicated in "walking pneumonia"?

A

Mycoplasma pneumoniae

91
Q

What are the classic symptoms of the pneumonia that is caused by Mycoplasma pneumoniae?

A

Insidious onset, headache, nonproductive cough, and diffuse interstitial infiltrates seen on chest x-ray

92
Q

What is a classic characteristic of chest x-ray findings in pneumonia caused by Mycoplasma?

A

The x-ray shows bilateral interstitial infiltrates, making the patient appear much sicker than he/she is

93
Q

Mycoplasma pneumoniae infection is associated with a high titre of what antibodies?

A

Cold agglutinins (immunoglobulin M)

94
Q

Mycoplasma pneumoniae can be grown on what medium?

A

Eatons agar

95
Q

What is the best treatment for Mycoplasma pneumoniae infection?

A

Tetracycline or erythromycin

96
Q

Why is Mycoplasma pneumoniae resistant to all penicillins?

A

Because it has no cell wall

97
Q

Mycoplasma cell membranes are distinct because they contain _____.

A

Cholesterol

98
Q

What age group is most commonly affected by Mycoplasma pneumoniae infection?

A

Individuals younger than 30 years of age

99
Q

A military recruit presents with a slow-onset, nonproductive cough with headache. Chest x-ray shows diffuse interstitial infiltrates, although the patient feels well. What is the likely diagnosis and how would you treat?

A

Mycoplasma pneumoniae; treatment with tetracycline or erythromycin

100
Q

Why are Mycoplasma pneumoniae not seen on gram stain?

A

No cell walls

101
Q

The tick Ixodes, which carries Borrelia burgdorferi, is also the vector for what other pathogen?

A

Babesia

102
Q

A child in Connecticut presents with Bells palsy. What infectious disease must be considered as a diagnosis?

A

Lyme disease

103
Q

Treponemes belong to what group of bacteria?

A

Spirochetes