A 64-year-old man comes to the office due to 2 days of dysuria, urinary frequency, and urgency. He recently underwent a cystoscopy for evaluation of hematuria. The patient has a history of hypertension, type 2 diabetes mellitus, and 30 pack-years of cigarette smoking. His temperature is 38.2 C (100.8 F). On examination, there is suprapubic tenderness on deep palpation but no costovertebral angle tenderness. Urinalysis findings are as follows: Midstream urine culture grows gram-positive cocci in chains with growth 100,000 colony-forming units/mL. The organism responsible for this patient's condition is most likely to demonstrate which of the following?

Question

A 64-year-old man comes to the office due to 2 days of dysuria, urinary frequency, and urgency.  He recently underwent a cystoscopy for evaluation of hematuria.  The patient has a history of hypertension, type 2 diabetes mellitus, and 30 pack-years of cigarette smoking.  His temperature is 38.2 C (100.8 F).  On examination, there is suprapubic tenderness on deep palpation but no costovertebral angle tenderness.  Urinalysis findings are as follows:  Midstream urine culture grows gram-positive cocci in chains with growth >100,000 colony-forming units/mL.  The organism responsible for this patient's condition is most likely to demonstrate which of the following?

Quizplus · Accepted Answer

11ec160b_3878_9324_9249_df44bdbcf6cf_MD0001_00 This patient who recently underwent a genitourinary procedure (cystoscopy) has a urinary tract infection caused by Enterococcus. This organism has a morphology of gram-positive cocci in pairs and chains and, when grown on blood agar, reveals no hemolysis (gamma hemolysis). Other characteristics of enterococci include pyrrolidonyl arylamidase (PYR) positivity and ability to grow in bile and in 6.5% sodium chloride. They are unable to convert nitrates to nitrites, explaining this patient's negative result on urinalysis nitrite. Enterococci are part of the normal intestinal flora of humans and animals. Enterococcus faecalis and E faecium are the most prevalent species cultured from humans and can cause urinary tract infection, bacteremia/endocarditis, wound infection, or intraabdominal or pelvic infection in the nosocomial setting. Enterococci have both intrinsic (beta-lactams, macrolides, aminoglycosides, trimethoprim-sulfamethoxazole) and acquired (vancomycin) resistance to antibiotics, making them important nosocomial pathogens. (Choice A) The ability to decompose hydrogen peroxide is suggestive of the presence of catalase, which would indicate Staphylococcus (which are gram-positive cocci in clusters not chains). (Choice C) Enterococci are aerobic organisms. Examples of anaerobic gram-positive cocci include Peptostreptococcus and Micrococcus. (Choice D) Oxidase positivity (possession of cytochrome oxidase) can help identify certain gram-negative organisms (eg, Pseudomonas). (Choice E) Staphylococcus aureus produces golden yellow pigments. Other bacteria producing pigments include Pseudomonas aeruginosa (blue-green) and Serratia marcescens (red). Educational objective: Enterococcus is an important cause of urinary tract infections. These organisms are gram-positive cocci in pairs and chains and, when grown on blood agar, they do not cause hemolysis (gamma-hemolytic). __________ References: Emergence of Enterococcus as a significant pathogen. (http://www.ncbi.nlm.nih.gov/pubmed/1623072) The life and times of the Enterococcus. (http://www.ncbi.nlm.nih.gov/pubmed/2404568)

A 64-Year-Old Man Comes to the Office Due to 2