A 24-year-old woman comes to the office due to 2 days of burning during urination and increased urinary frequency and urgency. The patient has had no fever, chills, nausea, vomiting, flank pain, or vaginal discharge, but reports darkening of the urine. She has no other medical conditions and does not use tobacco, alcohol, or drugs. The patient is sexually active with her boyfriend and takes an oral contraceptive for birth control. Vital signs are within normal limits. Physical examination shows mild suprapubic tenderness. There is no costovertebral angle tenderness. Which of the following pathogens is most likely responsible for this patient's symptoms?

Question

A 24-year-old woman comes to the office due to 2 days of burning during urination and increased urinary frequency and urgency.  The patient has had no fever, chills, nausea, vomiting, flank pain, or vaginal discharge, but reports darkening of the urine.  She has no other medical conditions and does not use tobacco, alcohol, or drugs.  The patient is sexually active with her boyfriend and takes an oral contraceptive for birth control.  Vital signs are within normal limits.  Physical examination shows mild suprapubic tenderness.  There is no costovertebral angle tenderness.  Which of the following pathogens is most likely responsible for this patient's symptoms?

Quizplus · Accepted Answer

This patient with painful urination, urinary frequency/urgency, and suprapubic tenderness has acute cystitis, a urinary tract infection (UTI) confined to the bladder. Most cases arise when fecal organisms gain access to the urethral meatus and subsequently ascend into the bladder. Escherichia coli, a gram-negative coliform bacteria, causes >70% of UTIs; other Enterobacteriaceae organisms, such as Klebsiella pneumoniae and Proteus mirabilis (Choices F and H), are also common but much less so than E coli. Women develop UTIs much more often than men due to the proximity of the anus and vaginal introitus and the short length of the female urethra. (Choice A) Candida albicans is a common cause of vulvovaginitis, which usually presents with vaginal discharge, burning, and pruritis. (Choices B and G) Chlamydia trachomatis and Neisseria gonorrhoeae are leading sexually transmitted pathogens. Although urethritis symptoms (eg, dysuria) can occur, most symptomatic women have significant mucopurulent vaginal discharge. Suprapubic tenderness is less common. (Choice D) Bacterial vaginosis occurs when normal vaginal flora (eg, Lactobacillus) is replaced with facultative anaerobes such as Gardnerella vaginalis. Most cases are asymptomatic, but some individuals have thin, whitish vaginal discharge and a fishy vaginal odor. (Choice E) Group B streptococcus commonly colonizes the genital and gastrointestinal tract and rarely causes infection. However, it can be passed to infants during vaginal birth, leading to early neonatal sepsis. (Choices I and J) Pseudomonas aeruginosa and Staphylococcus aureus are uncommon UTI pathogens in healthy, young women. However, they can cause cystitis in those who have recently received antibiotics or have been hospitalized. Both organisms are much less common than E coli. Educational objective: Urinary tract infections are most common in women and are typically caused by enteric pathogens. Escherichia coli is the leading pathogen.

A 24-Year-Old Woman Comes to the Office Due to 2