Deck 43: Obligate Intracellular and Non-culturable Bacterial Agents

Question 1

The most common sexually transmitted bacterial pathogen and a major cause of pelvic inflammatory disease (PID)is:

A) Rickettsia rickettsii.
B) Chlamydia trachomatis.
C) Klebsiella granulomatis.
D) Coxiella burnetii.

Answer 1

B
C.trachomatis causes significant infection and disease worldwide.In the United States, C.trachomatis is the most common sexually transmitted bacterial pathogen and a major cause of PID.An estimated 3 million C.trachomatis infections occur annually in the United States.

Question 2

Binary fission within vacuoles divides which of the following forms of Chlamydia?

A) RB
B) EB
C) Replicate body
D) Initial body

Answer 2

A
Binary fission within vacuoles divides the RB.As the numbers of RB increase, the vacuole expands, forming an intracytoplasmic inclusion.The RB then reverts to the EB, and 48 to 72 hours after infection, the EB is released from the host cell.

Question 3

The drug of choice for the treatment of granuloma inguinale, which is a major cause of genital ulcers in India, New Guinea, and part of South America, is:

A) clindamycin.
B) doxycycline.
C) imipenem.
D) gentamycin.

Answer 3

B
The organism that causes genital ulcers is Klebsiella granulomatis.Granuloma inguinale is uncommon in the United States but is recognized as a major cause of genital ulcers in India, Papua New Guinea, the Caribbean, Australia, and parts of South America.The causative agent is sexually transmitted, although the possibility exists that it may be nonsexually transmitted as well.No antibiotic susceptibility testing is performed.Doxycycline and trimethoprim-sulfamethoxazole combination are the most effective drugs for the therapy of granuloma inguinale.

Question 4

Tropheryma whipplei is characterized by the presence of periodic acid-Schiff (PAS)-staining macrophages, which indicates mucopolysaccharide or glycoprotein, in almost every organ system.Without treatment, this disease is uniformly fatal.Identification is achieved using:

A) enzyme-linked immunosorbent assay (ELISA).
B) IFA.
C) immunoblotting.
D) real-time polymerase chain reaction (PCR).

Question 5

Which of the following vectors transmit scrub typhus?

A) Lice
B) Ticks
C) Fleas
D) Chiggers

Question 6

The Coxiella burnetii, an acute systemic infection, primarily affects the lungs and can exist in two antigenic states.The reference method that is both highly specific and sensitive and is recommended for identification is:

A) immunofluorescent antibody (IFA).
B) direct fluorescent antibody (DFA).
C) Western blot.
D) latex agglutination.

Question 7

A prokaryote that differs from most other bacteria with respect to its very small size and obligates intracellular parasitism is:

A) Rickettsia.
B) Ehrlichia.
C) Calymmatobacterium.
D) Coxiella.

Question 8

Of the following organisms, which can be described as a fastidious obligate intracellular parasite that multiplies by binary fission in the cytoplasm of host cells and infects humans as accidental hosts in most cases?

A) Rickettsia
B) Chlamydia
C) Calymmatobacterium
D) Coxiella

Question 9

A Weil-Felix test was performed on serial dilutions from a patient bitten by a tick.The results obtained were positive for OX-19 and negative for OX-2 and OX-K.Based on these findings, the organism can be identified as:

A) Rickettsia rickettsii.
B) Orientia tsutsugamushi.
C) Rickettsia prowazekii.
D) Rickettsia typhi.

Question 10

Of the following organisms, which has a unique developmental life cycle including a replicative form, the reticulate body (RB), and an extracellular, metabolically inert, infective form, the elementary body (EB)?

A) Rickettsia
B) Chlamydia
C) Ehrlichia
D) Coxiella