A case study of symptomatic urinary tract infection by Shigella sonnei in adult female and a short review on drug-resistant Shigella species

Abstract

Shigella species belong to family Enterobacteriaceae and are causative agents of bacillary dysentery. The whole spectrum of disease caused by Shigella species is called Shigellosis. Shigella has four major subgroups: Shigella dysenteriae, Shigella flexneri, Shigella boydii, and Shigella sonnei. S. sonnei causes the mildest form of bacillary dysentery, and in many cases, it causes only mild diarrhea. It is the most common Shigellosis in developed countries. There are few reported cases of asymptomatic bacteriuria due to S. sonnei both in adults and pediatric patients. Few cases of symptomatic urinary tract infection (UTI) are also reported. In pediatric patients, the common risk factor for UTI is found to be vesicoureteric reflux, especially in females. Recent studies done in various countries show an alarming increase in resistance of Shigella species to commonly used antibiotics such as chloramphenicol, ampicillin, co-trimoxazole, nalidixic acid, fluoroquinolones, macrolides, and cephalosporins. Many outbreaks of Shigellosis by multidrug-resistant (MDR) strains have also been reported. Shigella rarely causes extraintestinal manifestations such as hemolytic uremic syndrome, hyponatremia, reactive arthritis, altered neurologic state, bacteremia, UTI, and vulvovaginitis. UTI is a rare complication of Shigella infection. Here, we report a case of UTI due to S. sonnei in an adult female with diabetes mellitus (DM). We have also done a short review of increasing antibiotic resistance among Shigella species. The Institutional Ethics Committee approval was obtained to publish this case study. A 64-year female presented to an outpatient clinic with symptoms of UTI. Urine culture was done by the semi-quantitative method in blood agar plate and MacConkey agar. A Gram-negative bacilli were isolated with a significant colony count of >100,000 cfu/ml. Antibiotic sensitivity was done by both disc diffusion method and minimum inhibitory concentration. Stool culture was also done after 4 days. In this case study, S. sonnei was isolated from urine, but stool culture done after 4 days of treatment with antibiotic was negative. The patient was newly diagnosed with type 2 DM. Hence, DM could be a risk factor for S. sonnei UTI in the elderly. Taking into consideration the emergence of antibiotic resistance among S. sonnei isolates, knowledge of antibiotic sensitivity pattern is crucial in the treatment of such infections. In our study, the isolate was not MDR. It was sensitive to ampicillin, cefixime, cefotaxime, ciprofloxacin, nitrofurantoin, and norfloxacin and azithromycin and resistant to co-trimoxazole and nalidixic acid.