Molecular Characterization of Streptococcus Agalactiae Isolates from Urine Samples of Patients Referred to Yazd City Medical Centers, Iran

Streptococcus agalactiae, a group B streptococcus (GBS), is commonly found in the vagina, rectum, and urinary tract of pregnant and non-pregnant women. This bacterium, not only causes neonatal infections, but also causes invasive diseases including urinary tract infections in pregnant women and non-pregnant adults. Penicillin and macrolides are the main antibiotics in the treatment of GBS infections, but the prevalence of resistant strains is increasing. On the other hand, the distribution of bacterial capsule serotypes varies depending on the sampling time, geographical location and type of sample, and it is necessary to determine the most common type of capsule type in preparing a suitable vaccine. The aim of this study was to investigate the antimicrobial resistance and capsular serotypes in GBS isolated from urine samples of patients referred to Yazd City medical centers, Iran.

This descriptive cross-sectional study was performed on 85 GBS isolates from 6068 urine positive culture samples for phenotypic survey and determining the pattern of antibiotic resistance to antibiotic disks using Kirby-Bauer method. Moreover, capsular serotypes of isolates were determined by multiplex polymerase chain reaction (PCR).

The frequency of GBS in urinary samples was 1.4%. The highest antibiotic resistance was to tetracycline (97.6%) and the lowest to penicillin (0.0%). The predominant capsular serotype was III (50.6%) followed by serotypes Ib (14.1%), V (12.9%), IV (7.1%), and II (5.9%). 9.4% of isolates were non-typeable.

The prevalence of GBS in urinary specimens was low, and capsular serotype III was predominant as in previous studies. Macrolide resistance is increasing in urinary GBS isolates.