[What are we learning about Staphylococcus saprophyticus?].
BACKGROUND
Staphylococcus saprophyticus is frequent cause of urinary tract infection in women; hence, it is important to know the epidemiology and antibiotic susceptibility of this microorganism.


METHODS
A retrospective longitudinal study was performed in urine specimens from outpatients in our health area cultured in the Microbiology Laboratory of C.E. Argüelles (Madrid, Spain) over a 10-year period (1997-2006).


RESULTS
Among 35,136 urine cultures with a significant count, we identified 331 S. saprophyticus (0.9%); 324 in women and 7 in men. Mean age of the infected patients was 32.7 years. A total of 83.9% of the strains were in women aged 15 to 44 years (37 women in this group were pregnant) and the largest numbers of isolates were found during the months of June and November. All S. saprophyticus strains were susceptible to vancomycin, rifampin, gentamicin and amoxicillin-clavulanic acid. Of note, there was a high percentage of resistance to erythromycin (37.7%) (96% consistent with the MSB phenotype) which has significantly increased since 1997 (P < 0.05); 1.5% were also resistant to clindamycin. Only 0.9% were resistant to fluorquinolones. Resistance to chloramphenicol, trimethoprim/sulfamethoxazole, and penicillin was 3.9%, 6%, and 55.6%, respectively. Based on the 2006 CLSI guidelines, 45% of S. saprophyticus isolates were considered oxacillin-resistant.


CONCLUSIONS
These results suggest the following: First, S. saprophyticus should be considered among agents causing urinary tract infection in women 15 to 44 years old, including pregnant women, particularly during spring and autumn. Second, cotrimoxazole may be an excellent option for treating cystitis in patients without risk factors. Third, almost half of S. saprophyticus strains were considered oxacillin-resistant, thereby denying the benefit of treatment with oral beta-lactams in urinary tract infections. This is especially important in pregnant women, who should avoid trimethoprim/sulfamethoxazole and quinolones (FDA Group C), as well as fosfomycin, with in vitro resistance.
Orden-Martínez
Beatriz
B
Servicio de Microbiología, Hospital Universitario Puerta de Hierro, Centro de Especialidades Argüelles, Madrid, España. beatrizorden.m@gmail.com
Martínez-Ruiz
Rocío
R
Millán-Pérez
Rosario
R
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000075202:Contraindications; D004338:Drug Combinations; D024901:Drug Resistance, Multiple, Bacterial / Q000502:physiology; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology; D005578:Fosfomycin / Q000494:pharmacology; D006801:Humans; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D012189:Retrospective Studies; D013030:Spain / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D013210:Staphylococcus / Q000187:drug effects / Q000302:isolation & purification / Q000472:pathogenicity / Q000502:physiology*; D013419:Sulfamethizole / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D014552:Urinary Tract Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D055815:Young Adult; D000096926:Benzenesulfonamides
D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D024841:Fluoroquinolones; D005578:Fosfomycin; D013419:Sulfamethizole; D014295:Trimethoprim; C029078:trimethoprim sulfamethizole; D000096926:Benzenesulfonamides