Isolation of Staphylococcus aureus Urinary Tract Infections at a Community-Based Healthcare Center in Riyadh

Abstract

Background The aim of this study was to assess the clinical presentation, risk factors, and comorbidities of the patients with Staphylococcus aureus bacteriuria, and to analyze the antimicrobial susceptibility data of S. aureus isolated from their urine samples. Methods A total of 90 isolates of S. aureus were collected from patients with urinary tract infections (UTIs). Urinalysis was performed manually, including macroscopic examination of color and appearance, and microscopic examination for the presence of urinary WBCs, RBCs, and bacteria. Full identification and susceptibility testing of S. aureus were performed by the VITEK 2 system (BioMérieux, Marcy-l'Étoile, France) using standard criteria. Results The majority of the patients were female (62%), with a mean age of 32.9 years. Most of the patients were outpatients (85%), and 52% were previously healthy with no underlying disease. Seventy positive urine cultures were associated with UTI symptoms, and the most common symptom was dysuria (40%). Out of 77 urinalyses performed, 58 were positive for UTI. Of the S. aureus isolated, 24% were methicillin-resistant S. aureus (MRSA). Susceptibility to vancomycin, teicoplanin, and linezolid was 100%, while susceptibility to erythromycin, clindamycin, gentamicin, trimethoprim-sulfamethoxazole, fusidic acid, and tetracycline, was 86%, 93%, 97%, 91%, 68%, and 87%, respectively. Conclusion Although S. aureus UTI is known to be associated with other risk factors such as urinary catheterization, long hospital stay, or complicated UTI, our results show the community-acquired presentation of UTI. Trimethoprim-sulfamethoxazole may be used as an effective treatment for UTI caused by S. aureus. S. aureus UTI could be an alarming sign of more invasive infections such as S. aureus bacteremia, though clinical evaluation and finding the source of S. aureus are crucial for effective treatment and prevention of further complications.

Keywords: antibiotic resistance; bacteriuria; staphylococcus aureus; urinary tract infection; urine culture.

Figure 1. Percentage of S. aureus urinary tract infections among other uropathogens.