A 17-year-old girl comes to the clinic due to 3 days of a burning sensation while urinating. Today, she noticed spotting on toilet paper after voiding. The patient is sexually active with 3 male partners and does not use condoms consistently. She has regular monthly menses and received outpatient treatment for pelvic inflammatory disease last year. The patient recently completed a course of antibiotics for group A Streptococcus pharyngitis. Vital signs are normal. Physical examination elicits lower abdominal tenderness. Pelvic examination shows clear cervical discharge and no cervical motion tenderness. Urinalysis reveals positive nitrites, positive leukocyte esterase, and 50 white blood cells/hpf. Urine β-hCG is negative. Which of the following is the most likely pathogen causing this patient's presentation?

Question

A 17-year-old girl comes to the clinic due to 3 days of a burning sensation while urinating.  Today, she noticed spotting on toilet paper after voiding.  The patient is sexually active with 3 male partners and does not use condoms consistently.  She has regular monthly menses and received outpatient treatment for pelvic inflammatory disease last year.  The patient recently completed a course of antibiotics for group A Streptococcus pharyngitis.  Vital signs are normal.  Physical examination elicits lower abdominal tenderness.  Pelvic examination shows clear cervical discharge and no cervical motion tenderness.  Urinalysis reveals positive nitrites, positive leukocyte esterase, and 50 white blood cells/hpf.  Urine β-hCG is negative.  Which of the following is the most likely pathogen causing this patient's presentation?

Quizplus · Accepted Answer

11ec25c8_d2b3_d323_bc81_379579698d01_MD0003_00 This patient's dysuria and abnormal urinalysis are consistent with a urinary tract infection (UTI). A UTI is typically acquired when enteric bacteria, most commonly Escherichia coli, are introduced to the vaginal introitus and ascend the urethra to the bladder. Women are at increased risk for UTI due to a shorter urethra and a smaller distance between the anus and urinary meatus. Recent sexual activity is a common predisposing factor because bacteria can enter the introitus during intercourse. Symptoms of UTI commonly include dysuria, urgency, frequency, and suprapubic pain; hematuria can also occur, as seen in this patient. Urinalysis reveals pyuria (ie, white blood cells) and positive leukocyte esterase (produced by white blood cells). Positive nitrites are specific for gram-negative bacteria belonging to the Enterobacteriaceae family (eg, E coli, Klebsiella, Proteus) because these organisms convert urinary nitrates to nitrites. Urine culture confirms the presence of bacteria. Treatment is with antibiotics. Untreated cystitis can spread from the ureters to the kidneys, leading to pyelonephritis. (Choice A) Candida albicans can cause UTI in patients with predisposing factors (eg, hospitalization, diabetes, catheterization) that are not present in this patient. Candida vulvovaginitis can also cause dysuria but typically presents with thick vaginal discharge and itching. Moreover, urinary nitrites would not be positive. (Choices B and F) Chlamydia trachomatis and Trichomonas vaginalis are sexually transmitted infections that can cause dysuria but typically present with mucopurulent vaginal discharge, which is not seen in this patient whose clear cervical discharge is likely physiologic. In addition, unlike in UTI, examination in Chlamydia cervicitis with or without urethritis shows cervical motion tenderness. (Choices D and E) Pseudomonas aeruginosa and Staphylococcus aureus are typically responsible for UTIs in hospitalized patients with indwelling catheters. These bacteria are uncommon in young, healthy women. In addition, neither organism would cause positive nitrites on urinalysis. Educational objective: Urinary tract infections (UTIs) are most commonly caused by Escherichia coli ascending the urethra to the bladder. Women often develop UTIs with dysuria, hematuria, and pyuria after sexual activity. Positive urinary nitrites support the presence of E coli, and urine culture is diagnostic. References: Urinary tract infection pathogenesis: host factors. (http://www.ncbi.nlm.nih.gov/pubmed/24484581) Diagnosis and management of urinary tract infections in the outpatient setting: a review. (http://www.ncbi.nlm.nih.gov/pubmed/25335150)

A 17-Year-Old Girl Comes to the Clinic Due to 3