High prevalence of group B streptococcus ST17 hypervirulent clone among non-pregnant patients from a Hungarian venereology clinic

Background

Although Streptococcus agalactiae is the leading causative agent of neonatal sepsis and meningitis, recently it is increasingly isolated from non-pregnant adults. The relation between its presence in the genitourinary tract and manifested clinical symptoms of STD patients remains an open question. In this study, a complex epidemiological investigation of GBS isolates from a venerology clinic was performed.

Methods

Ninety-six GBS isolates were serotyped and their genetic relatedness determined by PFGE. MLST was also performed for a subset of 20 isolates. The antibiotic susceptibility was tested with agar dilution. Surface proteins and the ST-17 hypervirulent clone was detected by PCR.

Results

The serotype prevalence was the following: V (29.2%), III (27.1%), Ia (22.9%), IV (10.4%), II (5.2%) and Ib (4.2%). A strong association was demonstrated between surface protein genes and serotypes. All isolates were fully susceptible to penicillin, but erythromycin and clindamycin resistance was high (41.7 and 35.4%, respectively), and 8 phenotypically macrolide sensitive isolates carried the ermB gene.

21.9% of all strains belonged to the hypervirulent ST17 clone, most being of serotype III and all were rib +. We found a few serotype IV isolates belonging to several STs and one serotype V/ST110 strain, containing a 44-bp deletion in the atr allele.

Conclusions

The presence of silent ermB genes is of worry, as their expression upon macrolide exposure could lead to unforeseen therapeutic failure, while clindamycin is used for intrapartum antibiotic prophylaxis, in case of penicillin allergy. The other alarming result is the high prevalence of ST17 among these strains from STD patients, who could be sources of further infections.

This is the first report from Hungary providing both serotyping and genotyping data of GBS isolates. These results could be helpful for vaccine production as the major vaccine candidates are capsular antigens or surface proteins.

The ABCs of Perineal Streptococcal Dermatitis

Perineal streptococcal dermatitis (PSD) is largely known to be caused by group A β-hemolytic Streptococcus (GAS). We would like to bring cases of non-GAS PSD to the attention of dermatologists, as there are implications for workup and therapy. We report 3 pediatric cases of PSD: 1 caused by GAS, 1 caused by group B β-hemolytic Streptococcus (GBS), and 1 associated with group C β-hemolytic Streptococcus (GCS). GBS and GCS are very rarely reported in pediatric cases of PSD. The literature on non-GAS PSD is reviewed, which additionally revealed several instances of PSD caused by group G β-hemolytic Streptococcus (GGS) and Staphylococcus aureus. GBS, GCS, GGS, and S aureus are significant causes of PSD to consider, particularly among adult patients, based on our encountered cases and the literature. If using rapid antigen tests to expedite the diagnosis of GAS, we recommend supplementing with a lesional swab for bacterial culture and sensitivity as the rapid antigen test does not detect non-GAS organisms. Therapy should be tailored to the microbiologic cause.