WBR0252

Author	[[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Infectious Disease
Prompt	[[Prompt::A 28- year old female presents to the physicians office with complaints of vaginal odor, itching, pain and discharge. Examination shows a thin gray homogeneous fluid that is adherent to the vaginal mucosa. The labia, introitus, cervix and cervical discharge appear normal. Microscopic examination of the discharge demonstrates clue cells, with a PH of greater than 5 and gram-negative cells are dominant. What is the likely etiologic agent?]]
Answer A	AnswerA::Gardnerella vaginalis
Answer A Explanation	AnswerAExp::Gardnerella vaginalis is the causative agent of bacterial vaginosis presenting as a gray vaginal discharge with a fishy smell with clue cells and increased PH greater than 4.5 diagnostic.
Answer B	AnswerB::Candida albicans
Answer B Explanation	[[AnswerBExp::Candida albicans are yeasts with pseudohyphae and hyphae that form germ tubes at 37 degree Celsius in serum.]]
Answer C	AnswerC::Trichomonas vaginalis
Answer C Explanation	[[AnswerCExp::Trichomonas vaginalis causes foul-smelling greenish discharge, itching and burning and it is sexually transmitted. It is seen as motile trophozoites in methylene blue wet mount; and shows corkscrew motility.]]
Answer D	AnswerD::Neisseria gonorrhea
Answer D Explanation	[[AnswerDExp::Neisseria gonorrhea is a-gram-negative kidney bean-shaped diplococci that can cause vaginal discharge but not the characteristic thin gray vaginal discharge with a fishy odor seen in bacterial vaginosis.]]
Answer E	AnswerE::Chlamydia trachomatis
Answer E Explanation	[[AnswerEExp::Chlamydia trachomatis is not seen on gram stain and it is an obligate intracellular bacterium that cannot make ATP. In adults, it causes urethritis, cervicitis, pelvic inflammatory disease, inclusion conjunctivitis and in neonates, it causes inclusion conjunctivitis and neonatal pneumonia.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient in this vignette has Bacterial vaginosis, caused by Gardnerella vaginalis. It is a facultative anaerobic gram-negative (pleomorphic) rod, catalase and oxidase negative. It works synergistically with other normal flora organisms like lactobacillus, mobiluncus, bacteroides and peptostreptococcus. It flourishes with increased vaginal PH of > 4.5. Diagnostic clues include clue cells (these are epithelial cells covered with bacteria), PH > 5, female with thin, gray homogenous discharge. Infection also follows menses or antibiotic therapy and the Whiff test with KOH to the sample has a characteristic “fishy” amine odor. Treatment is with Metronidazole or Clindamycin. Educational Objective Gardnerella vaginalis is the causative agent of bacterial vaginosis and it is a gram-negative rod seen as a thin, gray homogenous fluid with clue cells and PH greater than 4.5. Educational Objective: References: ]]
Approved	Approved::Yes
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