Micro - Clinical Bacteriology (Gram - Misc)

Question 1

What is the functional limitation of Chlamydiae, and why?

Answer 1

They are obligate intracellular organisms that cause mucosal infections; Chalmydiae cannot make their own ATP; Think: “Chlamys = cloak (intracellular)”

Question 2

What (broad) kind of infections does Chlamydiae cause?

Answer 2

Mucosal infections

Question 3

What are the 2 forms of Chlamydiae? What is important to remember about the differing roles/characteristics of these two forms?

Answer 3

(1) Elementary body - Infectious, enters cell via endocytosis. Transforms into reticulate body (2) Reticulate body - Replicates in cell by fissure, recognizes into elementary bodies; Think: “Elementary = Enfectious, Enters cell, Endocytosis, Reticulate = Replicates once in cell”

Question 4

What 4 diseases/conditions does Chlamydia trachomatis cause?

Answer 4

(1) Reactive arthritis (Reiter syndrome) (2) follicular Conjuctivitis (3) Nongonococcal urethritis (4) Pelvic inflammatory disease (PID)

Question 5

Besides C. trachomatis, what are the other species of Chlamydiae? How are they transmitted? What disease/condition do they cause?

Answer 5

(1) C. pneumoniae (2) C. psittaci; Transmitted by aerosol; Atypical pneumonia

Question 6

What are the treatment options for Chlamydiae infection? Which is favored, and why?

Answer 6

Azithromycin (favored because one-time treatment) or Doxycycline

Question 7

What is a notable reservoir for Chlamydophila psittaci?

Answer 7

Avian

Question 8

How is a lab diagnosis of Chlamydiae infection made?

Answer 8

Cytoplasmic inclusion seen on Giemsa or fluorescent antibody-stained smear

Question 9

What is unusual about the Chlamydial cell wall?

Answer 9

Lacks muramic acid

Question 10

What are the serotypes of Chlamydia trachomatis? List them based on similar presentations.

Answer 10

(1) Types A, B, and C (2) Types D-K (3) Types L1, L2, and L3

Question 11

What disease/condition(s) do C. trachomatis serotypes A, B, and C cause, and where in the world?

Answer 11

Chronic infection, cause blindness due to follicular conjuctivitis in Africa; Think: “ABC = Africa, Blindness, (Conjuctivitis)/Chronic infection and D-K - everything else”

Question 12

What disease/condition(s) do C. trachomatis serotypes D-K cause?

Answer 12

Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), or neonatal conjuctivitis

Question 13

How can neonatal Chlamydial disease be acquired?

Answer 13

During passage through infected birth canal

Question 14

What disease/condition(s) do C. trachomatis Types L1, L2, and L3 cause? What characterizes it? How is it treated?

Answer 14

Lymphogranuloma venereum; small , painless ulcers on genitals => swollen, painful inguinal lymph nodes that ulcerated (“buboes”); treat with doxycycline

Question 15

What condition/disease does Mycoplasma pneumoniae classically cause? How does it present clinically and appear on X-ray?

Answer 15

Atypical “walking” pneumonia; Insidious onset, headache, nonproductive cough, diffuse interstitial infiltrate, X-ray looks worse than patient

Question 16

With what immunological finding(s) and/or process(es) is Mycoplasma pneumoniae infection (Atypical “walking” pneumonia) associated? What can result from this/these immunological finding(s)?

Answer 16

High titer of cold agglutinins (IgM), which can agglutinate or lyse RBCs

Question 17

On what type of agar is Mycoplasma pneumoniae grown?

Answer 17

Eaton’s agar

Question 18

How is Mycoplasma pneumoniae infection treated? What antibiotic is ineffective, and why?

Answer 18

Macrolide, doxycycline, or Fluoraquinolone (Penicillin ineffective since Mycoplasma have no cell wall)

Question 19

How do Mycoplasma pneumoniae appear on Gram stain, and why?

Answer 19

Not seen on Gram stain; No cell wall

Question 20

What important content does Mycoplasma pneumonia contain is its membrane, and what role does this play?

Answer 20

Bacterial membrane contains sterols for stability

Question 21

In what patient population is Mycoplasma pneumonia more common? In what populations/settings are frequent outbreaks seen?

Answer 21

Patients < 30 years of age; Frequent outbreaks in military recruits and prisons

Question 22

What kind of organism is Gardnerella vaginalis, particularly in terms of morphology and gram stain?

Answer 22

A pleomorphic, gram-variable rod

Question 23

What condition does Gardnerella vaginalis cause, and how does this condition present?

Answer 23

Causes Vaginosis, presenting as a gray vaginal discharge with a fishy smell but nonpainful (vs vaginitis)

Question 24

With what is Gardnerella vaginalis associated? What is an important distinction to make with regards to this association?

Answer 24

Associated with sexual activity, but not an STD

Question 25

What pathogen causes Bacterial vaginosis? What characterizes/defines this condition?

Answer 25

Gardnerella vaginalis; Bacterial vaginosis is characterized by overgrowth of certain anaerobic bacteria in vagina

Question 26

What pathogen causes Bacterial vaginosis? What microscopic finding suggests Bacterial vaginosis?

Answer 26

Gardnerella vaginalis; Clue cells (vaginal epithelial cells covered with bacteria) are visible under the microscope

Question 27

How is Bacterial vaginitis due to Gardnerella vaginalis treated?

Answer 27

Metronidazole or (to treat anaerobic bacteria) clindamycin

Question 28

What is a way to remember the histological finding, primary presentation, location, and pathogen associated with Bacteria vaginosis?

Answer 28

i don’t have a CLUE why I smell FISH in the VAGINA GARDEN = Clue cells, gray discharge with fishy smell, caused by Gardnerella vaginalis

Question 29

What is the treatment for all Rickettsial disease and vector-borne illness?

Answer 29

Doxycycline

Question 30

What finding separates Rickettsial infections from other tick-borne illnesses?

Answer 30

Rash in Rickettsial infections; No rash in non-Rickettsial infections

Question 31

What pathogen causes Rocky Mountain spotted fever? What is its vector?

Answer 31

Rickettsia rickettsii, vector is tick

Question 32

Where does Rocky Mountain spotted fever primarily occur? Again, what pathogen causes it?

Answer 32

Despite its name, disease occurs primarily in the South Atlantic states, especially North Carolina; Rickettsia rickettsii

Question 33

Describe the rash seen in Rocky Mountain spotted fever.

Answer 33

Rash typically starts at wrists and ankles and then spreads to trunk, palms, and soles

Question 34

What kind of growth/metabolic requirements does Rickettsia rickettsii have?

Answer 34

Rickettsiae are obligate intracellular organisms that need CoA and NAD+ because they cannot synthesize ATP

Question 35

What are the kinds of Typhus caused by Rickettsial species? Which vector and Rickettsial species is associated with each?

Answer 35

(1) Endemic (fleas) - R. typhi (2) Epidemic (human body louse) - R. prowazekii

Question 36

What kind of Typhus does R. prowazekii cause? How does the rash seen in this condition appear?

Answer 36

Epidemic typhus; Rash starts centrally and spread out, sparing palms and soles

Question 37

What is the classic triad associated with Rocky Mountain spotted fever?

Answer 37

Headache, fever, rash (vasculitis);

Question 38

What is the difference between the rashes seen in Rickettsial Rocky Mountain spotted fever versus Typhus?

Answer 38

Rickettsia rickettsii = Rash typically starts at wrists and ankles and then spreads to trunk, palms, and soles; R. prowazekii = Rash starts centrally and spreads out, sparing palms and soles; Think: “Rickettsii on the wRists, Typhus on the Trunk.”

Question 39

What are the infections in which you see a palm and sole rash?

Answer 39

Palm and sole rash in seen in (1) Coxsackievirus A infection (hand, foot, and mouth disease) (2) Rocky Mountain Spotted Fever (3) Secondary Syphilis; Think: “you drive in CARS using your PALMS & SOLES”

Question 40

What are pathogens that are related to Rickettsial pathogens but do not cause rash? What condition/disease does each cause?

Answer 40

(1) Ehrlichia - Ehrlichiosis (2) Anaplasma - Anaplasmosis (3) Coxiella burnettii - Q fever

Question 41

What pathogen causes Ehrlichiosis? In what vector is this pathogen found? What characterizes Ehrlichiosis?

Answer 41

Ehrlichia; Tick; Monocytes with morula (berry-like inclusions) in cytoplasm

Question 42

What pathogen causes Anaplasmosis? In what vector is this pathogen found? What characterizes Anaplasmosis?

Answer 42

Anaplasma; Tick; Granulocytes with morula in cytoplasm

Question 43

What pathogen causes Q fever? How does it present? What is the source and mode of transmission of this pathogen? What is unique about this pathogen in contrast to related species?

Answer 43

Coxiella burnetii; Tick feces and cattle placenta release spores that are inhaled as aerosols (No arthopod vector); presents as pneumonia. Think: “Q fever is Queer because it has no rash or vector & its causative organism can survive outside in its endospore form. Not in the Rickettsia genus, but closely related.”

Question 44

How does Q fever present?

Answer 44

Presents as pneumonia; Think: “Q fever is Queer because it has no rash or vector & its causative organism can survive outside in its endospore form. Not in the Rickettsia genus, but closely related.”

Question 45

What is unique about Q fever (among other Rickettsial like diseases)?

Answer 45

Q fever = Queer because it has no rash or vector and its causative organism can survive outside in its endospore form

Question 46

Again, what pathogen causes Q fever? How does it relate to the Rickettsial genus?

Answer 46

Coxiella burnettii; Not in the Rickettsia genus, but closely related