Q. A 30-year-old sexually active woman presents with a painful vesicle on
her external genitalia and bilateral inguinal lymphadenopathy. A Tzanck
smear from the vesicle fails is negative, and polymerase chain reaction
analysis of viral DNA is negative. A VDRL assay is also negative. Which
of the following medications would be most helpful to this patient?
(A) Acyclovir
(B) Ceftriaxone
(C) Foscarnet
(D) Ribavirin
(E) Vancomycin
Ans: B.
The differential diagnosis of a genital ulcer in a sexually active patient should include primary syphilis (though these ulcers are usually painless), genital herpes, and chancroid.
Because the Tzanck smear (which looks for multinucleated giant cells typical of herpes infection), viral polymerase chain reaction (used to look for herpesvirus) are both negative, as is the VDRL to test for syphilis, chancroid becomes most likely.
Chancroid is a bacterial infection caused by Haemophilus ducreyi, which presents typically as a painful genital ulcer with associated inguinal lymphadenopathy. It is typically treated with ceftriaxone, though azithromycin or ciprofl oxacin can be used. Vancomycin is effective only
(A) Acyclovir
(B) Ceftriaxone
(C) Foscarnet
(D) Ribavirin
(E) Vancomycin
Ans: B.
The differential diagnosis of a genital ulcer in a sexually active patient should include primary syphilis (though these ulcers are usually painless), genital herpes, and chancroid.
Because the Tzanck smear (which looks for multinucleated giant cells typical of herpes infection), viral polymerase chain reaction (used to look for herpesvirus) are both negative, as is the VDRL to test for syphilis, chancroid becomes most likely.
Chancroid is a bacterial infection caused by Haemophilus ducreyi, which presents typically as a painful genital ulcer with associated inguinal lymphadenopathy. It is typically treated with ceftriaxone, though azithromycin or ciprofl oxacin can be used. Vancomycin is effective only
for gram-positive
organisms
A
is incorrect. Acyclovir is used to treat herpes infections. It is activated by viral thymidine kinase, whereupon it inhibits the herpes viral polymerase. It can be used to treat herpes simplex virus (HSV) types 1 and 2, varicella- zoster virus (VSV), and Epstein-Barr virus (EBV) infections. It is not effective for bacterial organisms.
C
is incorrect. Foscarnet inhibits viral DNA polymerase without the need of activation by thymidine kinase. It is used to treat cytomegalovirus (CMV) retinitis, but it can also be used
to treat acyclovir-resistant HSV.
D
is incorrect. Ribavirin is used to treat respiratory syncytial virus. It functions by inhibiting inosine monophosphate dehydrogenase, thus blocking the synthesis of guanine
nucleotides.
E
is incorrect. Vancomycin is a
bactericidal antibiotic used for multidrug-resistant gram-positive organisms such as Staphylococcus aureus
and Clostridium
diffi cile. It functions
by binding to mucopeptide precursors, preventing formation of
the bacterial cell wall
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