Clinical Bacteriology: Zoonotic Specifics and Others Flashcards
Patient presents with nonpainful vaginitis with a fishy-smelling gray vaginal discharge.
Microscopy of the discharge shows clue cells.
What organism is this? How would you treat?
Gardnerella vaginalis
“I don’t have a clue why I smell fish in the vagina garden!”
Treat with metronidazole or (to treat anaerobic bacteria) clindamycin.
Associated with sexual activity but not sexually trnasmitted. Associated with overgrowth of certain anaerobic bacteria in vagina.
What is the treatment for Rickettsial diseases and vector-borne diseases?
Doxycycline
Patient visiting from North Carolina presents with a headache, fever, and extensive rash that spread from his wrists and ankles to his trink, palms, and soles.
He confirms exposure to ticks.
What is this disease?
Rocky mountain spotted fever.
Most common in South Atlantic states (especially North Carolina)
Obligate intracellular organism, can’t synthesize ATP (lack CoA and NAD+)
Mnemonic for palm/sole rashes:
Palms and soles rash is seen in Coxsackievirus A infection (hand, foot, and mouth disease), Rocky mountain spotted fever, and secondary Syphilis.
(You drive CARS using your palms and soles).
A patient presents with a central rash that spares his palms and soles.
He confirms exposure to lice.
- Rickettsia prowazekii* (epidemic typhus) - spread by lice.
- Rickettsia typhi* (endemic typhus) - spread by fleas
Rickettsia on the wRists, Typhus on the Trunk.
Patient presents after tick bite.
Peripheral blood smear shows monocytes with berry-like inclusions in the cytoplasm.
What is that disease?
Ehrlichiosis - genus of Rickettsia. Rash rare in this disease.
Berry-like inclusions = morulae
Patient presents after tick bite.
Peripheral blood smear shows berry-like inclusions in the cytoplasm of Granulocytes.
What is that inclusion called?
Organism?
Anaplasmosis, genus of rickettsia - rash unlikely.
Morulae = berry-like inclusion in the cytoplasm.
A farmer presents with pneumonia.
Serological testing shows antibodies to Coxiella burnetii.
What disease does this cause? Vector/transmission?
Q fever.
No arthropod vector - tick feces and cattle placenta release spores that are inhaled as aerosols. Intracellular pathogen.
Q fever is Queer because it has no rash or vector and its causative organism can survive outside in its endospore form. Not in the Rickettsia genus, but closely related.
What is unique about the life cycle of Chlamydiae species?
Obligate intracellular organisms that cannot make their own ATP.
Chlamys = cloak (intracellular)
Two forms:
Elementary body (small, dense) is “Enfectious” and Enters cells via Endocytosis. Transforms in to the reticulate body.
Reticulate body Replicates in the cell by fission, reorganizes into elementary bodies.
What diseaes are caused by Chlamydia trachomatis?
Reactive arthritis (Reiter syndrome), follicular conjunctivitis, nongonococcal urethritis, and PID.
NOTE: Several serotypes! (cards on this later, A, B, C, D - K, L1, L2, L3)
What diseases are caused by C. pneumoniae and C. psittaci?
Atypical pneumonia; transmitted by aerosol
How do you diagnose chlamydia?
What is the treatment?
Lab diagnosis: Cytoplasmic inclusions seen on Giemsa or fluorescent antibody-stained smear.
Treat with azithromycin (favored due to one-time treatment) or doxycycline.
Extra note: Chlamydial cell wall unusual in that it does not contain muramic acid.
What diseases do Chlamydia trachomatis serotypes A, B, and C cause?
Chronic infection, cause blindness due to follicular conjunctivitis in Africa
ABC = Africa/Blindness/Chronic infection.
What diseases do Chlamydia trachomatis serotypes D - K cause?
Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis
D-K = everything else.
Neonatal disease acquired during passage through infected birth canal.
What diseases do Chlamydia trachomatis serotypes L1, L2, and L3 cause?
Lymphogranuloma venereum: Small, painless ulcers on genitals that progress to swollen, painful inguinal lymph nodes that ulcerate (“buboes”).
Treat with doxycycline.
A young inmate from a local prison presents with headache and nonproductive cough. A chest x-ray shows patchy infiltrates that look much worse than the patient’s symptoms suggest.
What is the organism?
Mycoplasma pneumoniae - “walking” pneumonia.
More common in patients < 30 years old, frequent outbreaks in military recruits and prisons.
No cell wall - not seen on gram stain. Bacterial membrane contains sterols for stability.
