Micro - Bacteriology Part 2 Flashcards
All mycobacteria have what staining property seen in this image?
They are all acid-fast
What bacteria causes syphilis?
Treponema pallidum
Treponema pertenue causes what condition?
Yaws
What tropical infection is not a sexually transmitted disease but results in a positive
venereal disease research laboratory test?
Yaws
What are the symptoms commonly associated with yaws?
Joint deformities following keloid healing of skin, bone and joint infection
First-degree syphilis presents with what type of lesion?
A painless chancre at the site of infection (localized disease)
Is second-degree syphilis a localized or disseminated disease?
Disseminated (remember: Secondary syphilis = Systemic)
Second-degree syphilis presents with what type of skin manifestations?
A maculopapular rash on palms and soles and condylomata lata
Third-degree syphilis presents with what signs and symptoms?
Gummas, aortitis, tabes dorsalis, and Argyll Robertson pupil
Which stage of syphilis is characterized by broad-based ataxia, a positive Romberg sign, Charcot joints, and stroke-like symptoms?
Third-degree syphilis
Third-degree syphilis can present with what neurologic defects?
Tabes dorsalis (resulting in broad-based gait, ataxia, and positive Romberg test) and Argyll Robertson pupil
What signs and symptoms are associated with congenital syphilis?
Saber shins, saddle-nose deformity, neurological (cranial nerve VIII) deafness,
Hutchinsons teeth, and mulberry molars
What is the treatment of choice for syphilis?
Penicillin G
Where can treponemes be found during primary and secondary syphilis?
In chancres during primary syphilis and in condylomata lata during secondary
syphilis
What causes aortitis in tertiary syphilis?
Destruction of the vasa vasorum
Argyll Robertson pupil is associated with what disease?
Tertiary syphilis
Describe the findings in a patient with an Argyll Robertson pupil.
Pupil dilation with accommodation but not with direct light
Which diagnostic test is most specific for treponemes, turns positive earliest during
the course of disease, and remains positive for the longest time?
Fluorescent treponemal antibody absorption test (remember: FTA-
ABS = Find The Antibody-ABSolutely)
A positive venereal disease research laboratory test and a positive fluorescent
treponemal antibody absorption test indicate what?
Active infection with a treponeme that causes syphilis
If a venereal disease research laboratory test is positive but the fluorescent
treponemal antibody absorption test is negative, what is the interpretation?
False-positive result for syphilis infection
What do negative venereal disease research laboratory test and positive fluorescent
treponemal antibody absorption test results indicate?
Successful treatment of syphilis
Which conditions give biologic false-positive results for the venereal disease
research laboratory test?
Viral infection, drugs, rheumatic fever, rheumatoid arthritis, systemic lupus
erythematosus, and leprosy. (remember: VDRL= Viruses, Drugs, Rheumatic fever
and arthritis, Lupus and leprosy)
A positive venereal disease research laboratory indicates that antibodies have
formed against what molecule?
Beef cardiolipin
Name six medically important zoonotic bacteria.
Bartonella henselae, Borrelia burgdorferi, Brucella spp, Francisella
tularensis, Yersinia pestis, and Pasteurella
multocida, Ella(remember: Big Bad Bugs From Your Pet named Ella)
What organism transmitted by dairy products and contact with animals causes
undulant fever?
Brucella spp (remember: Unpasteurized dairy products give you Undulant fever)
A dairy farmer presents with one week of fever that waxes and wanes without
treatment. What is the diagnosis?
Brucella spp, which are found in dairy products or transmitted via contact with
cows, sheep, and goats
How is Francisella tularensis transmitted?
Tick bites
What organism causes tularemia?
Francisella tularensis
Name two animal reservoirs for ticks that transmit Francisella tularensis.
Rabbits and deer
Which organism causes the plague?
Yersinia pestis
What is the mode of transmission of the bubonic plague?
Flea bites
What is the animal reservoir for ticks transmitting Yersinia pestis?
Rodents (especially prairie dogs)
How is Pasteurella multocida transmitted?
Animal bite (cats, dogs)
What infection is caused by Pasteurella multocida?
Cellulitis after cat and dog bites
What is the disease caused by Bartonella?
Cat scratch fever
What dermatologic finding can Bartonella cause in immunocompromised
individuals?
Bacillary angiomatosis (can be mistaken for Kaposi sarcoma)
What is the most common mode of transmission for the bacteria Bartonella
henselae?
Cat scratch
Cat scratch
What kind of discharge is produced in vaginosis caused by Gardnerella vaginalis?
Off-white/gray vaginal discharge, fishy odor
What is the treatment of choice for vaginosis caused by Gardnerella vaginalis?
Metronidazole
What kind of cells (seen on a wet mount of vaginal discharge) are diagnostic of
infection with Gardnerella vaginalis?
Clue cells (vaginal epithelial cells covered with bacteria)
What are clue cells?
Vaginal epithelial cells covered with bacteria to the point where intracellular
organelles are obscured
Is Gardnerella vaginalisconsidered a sexually transmitted disease?
No, it is not a sexually transmitted disease, although it is more common in sexually
active women
What anaerobic bacteria other than Gardnerella vaginalis is frequently involved in
vaginosis?
Mobiluncus
A women presents with fishy gray vaginal discharge. What is the likely diagnosis
and what will you prescribe?
Bacterial vaginosis caused by Gardnerella; treatment with metronidizole
True or False? Rickettsiae are facultative intracellular parasites.
False; Rickettsiae are obligate intracellular parasites
Rickettsiae are obligate intracellular parasites because they require which two
cofactors?
Coenzyme A and nicotinamide adenine dinucleotide
Rickettsiae are obligate intracellular parasites that are transmitted by what type of
vector?
Arthropods (except Coxiella, which is transmitted by aerosol)
Why is Coxiellaconsidered an atypical rickettsia?
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
What is the classic triad of symptoms caused by a rickettsial infection?
Fever, headache, and rash (vasculitis)
What disease does Rickettsia rickettsii cause?
Rocky Mountain spotted fever
The pathogen that causes Rocky Mountain spotted fever is carried by what vector?
Ticks
Endemic typhus is caused by what bacterium?
Rickettsia typhi
The pathogen that causes endemic typhus is carried by what vector?
Fleas
Epidemic typhus is caused by what bacterium?
Rickettsia prowazekii
The pathogen that causes epidemic typhus is carried by what vector?
Human body lice
Q fever is caused by what bacterium?
Coxiella burnetii
The pathogen that causes Q fever is carried by what vector?
Coxiella burnetii is an atypical Rickettsia in that it has no vector and is transmitted
via aerosol
What is the treatment of choice for all Rickettsial infections?
Tetracycline
How could one distinguish between the rash of Rocky Mountain spotted fever and
that of typhus?
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)
Which rickettsial disease does not present with a rash?
Q fever is the only rickettsial infection that does not cause a rash
Does Q fever have a positive or negative Weil-Felix reaction assay?
Negative; a Weil-Felix assay is usually positive for typhus and Rocky Mountain
spotted fever but negative for Q fever
True or False? Coxiella burnetiican survive outside of the body for a long time.
True; Coxiella burnetii is the only rickettsial pathogen that can survive outside the
body for long periods of time
Ehrlichia is carried by what type of vector?
Tick
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?
Rocky Mountain spotted fever; treatment with tetracycline
Rocky Mountain spotted fever is endemic to what area?
The East Coast; despite its name it is not seen in the Rocky Mountains
What three diseases start with a rash on the palms and soles?
Coxsackievirus A(hand-foot-and-mouth disease), Rocky Mountain spotted fever, and Syphilis (remember: you drive CARS with your palms and soles)
The Weil-Felix reaction is used to test for what pathogens?
Rickettsiae (this reaction is an assay for antibodies)
In a Weil-Felix reaction, antirickettsial antibodies in patient serum cross-react and
agglutinate when mixed with antigens from what pathogen?
Proteus
Which rickettsial infection will have a negative Weil-Felix reaction?
Coxiella burnetii(which causes Q fever)
What are the two forms of Chlamydiae?
The elementary body and the reticulate body
During their life cycle, what form of chlamydia is infectious (ie, enters host cells)?
The Elementary body (small, dense) Enters the body via Endocytosis
During their life cycle, what form of chlamydia replicates by fission?
The Reticulate (initial) body Replicates in the cell by fission
What diseases are caused by Chlamydia trachomatis?
Reactive arthritis, conjunctivitis, nongonococcal urethritis, cervicitis, and pelvic
inflammatory disease
Which two chlamydial species cause atypical pneumonia and how are they
transmitted?
Chlamydia pneumoniae and Chlamydia psittaci; both are transmitted by aerosol
Chlamydia psittaci has what animal reservoir?
Birds
What are the treatments of choice for chlamydial infections?
Erythromycin or tetracycline
How can chlamydial infection be diagnosed by microscopy?
By cytoplasmic inclusions seen on Giemsa or fluorescent antibody staining
The chlamydial cell wall is unique in that is lacks _____ _____.
Muramic acid
Why are Chlamydia intracellular organisms?
Because they cannot make their own adenosine triphosphate
Which Chlamydia trachomatis serotypes cause chronic infection and blindness in
Africa?
Types A, B, and C(remember: Africa, Blindness, Chronic infection)
Which Chlamydia trachomatisserotypes cause urethritis, pelvic inflammatory
disease, ectopic pregnancy, neonatal pneumonia, and neonatal conjunctivitis?
Types D through K
Which Chlamydia trachomatisserotypes cause lymphogranuloma venereum?
Types L1, L2, and L3 (remember: Lymphogranuloma)
What is the treatment of choice for neonatal disease caused by Chlamydia
trachomatis?
Oral erythromycin
What test is positive in lymphogranuloma venereum?
Frei test
When is neonatal Chlamydiaacquired?
As the infant passes through an infected birth canal
What are the symptoms of lymphogranuloma venereum?
Acute lymphadenitis
What other infection has similar symptoms to lymphogranuloma venereum?
Granuloma inguinale (donovanosis) caused by Calymmatobacterium granulomatis
What bacteria is most commonly implicated in “walking pneumonia”?
Mycoplasma pneumoniae
What are the classic symptoms of the pneumonia that is caused by Mycoplasma
pneumoniae?
Insidious onset, headache, nonproductive cough, and diffuse interstitial infiltrates
seen on chest x-ray
What is a classic characteristic of chest x-ray findings in pneumonia caused
by Mycoplasma?
The x-ray shows bilateral interstitial infiltrates, making the patient appear much
sicker than he/she is
Mycoplasma pneumoniaeinfection is associated with a high titre of what
antibodies?
Cold agglutinins (immunoglobulin M)
Mycoplasma pneumoniae can be grown on what medium?
Eatons agar
What is the best treatment for Mycoplasma pneumoniaeinfection?
Tetracycline or erythromycin
Why is Mycoplasma pneumoniae resistant to all penicillins?
Because it has no cell wall
Mycoplasma cell membranes are distinct because they contain _____.
Cholesterol
What age group is most commonly affected by Mycoplasma pneumoniaeinfection?
Individuals younger than 30 years of age
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?
Mycoplasma pneumoniae; treatment with tetracycline or erythromycin
Why are Mycoplasma pneumoniae not seen on gram stain?
No cell walls
The tick Ixodes, which carries Borrelia burgdorferi, is also the vector for what
other pathogen?
Babesia
A child in Connecticut presents with Bells palsy. What infectious disease must be
considered as a diagnosis?
Lyme disease
Treponemes belong to what group of bacteria?
Spirochetes
