Streptococcus group B isolates in a regional hospital area

Abstract

A survey of the frequency of group B streptococcal infections in the Sharon area (Isreal) was done in this laboratory. In the female genital tract streptococcus group B was found in 11.8%. This microorganism was recovered in lower frequencies (1.6%–7.4%) in other infection sites (CSF, wounds, throat, blood, and urine). The streptococci were identified as belonging to group B by biochemical properties such as resistance to bacitracin and capability to hydrolyze hippurate. Later the isolates were classified serologically. Serotypes Ib, Ic, and II were predominant in the vaginal smears (25%–28% each serotype). In the other infection sites serotype Ib was the most frequent (36%). The isolates were sensitive to penicillin, cloxacillin, cephalothin, and erythromycin — M.I.C. 0.1–0.2gmg/ml. Most of the isolates were resistant to tetracycline (69%) and some to chloramphenicol (17.5%). Synergism has been obtained in vitro using a combination of gentamicin and penicillin simultaneously.

Group B streptococci orStreptococcus agalactiae first became known because of association with bovine mastitis. This microorganism is now widely appreciated as a potent human pathogen. In several geographic regions it is the leading cause of meningitis during the first two months of life (Eickhoff et al. 1965; Franciosi et al. 1973; Baker et al. 1973; Patterson and Hafeez 1976; Anthony and Okada 1977; Baker 1977). Two clinical syndromes have been defined among infants. The first syndrome, called early onset, is observed in neonates aged five days or less (Baker et al. 1973). In older infants (between 10 days and three months of age) the second syndrome or the late-onset may appear (Franciosi et al. 1973; Baker et al. 1973). In the last few years infections in adults have also been reviewed (Bayer et al. 1976; Lerner et al. 1977).

Group B streptococci are divided into five serological types: Ia, Ib, Ic, II, and III (Wilkinson and Eagon 1971); some strains appear to be devoid of type-specific antigens and are called nontypable (NT). The serotypes of group B streptococci isolated from infants with early onset disease are identical with those isolated from the genital tracts of their mothers. Infants probably acquire the microorganism during passage through the birth canal (Baker and Barrett 1973). Furthermore, the genitourinary tract is known to be a major reservoir of infection and a source for subsequent dissemination in both men and women (Wilkinson 1978).

The appearance of sepsis and meningitis in neonates caused by group B streptococci and which was reported previously by this laboratory (Maayan et al. 1978; Nitzan et al. 1978) has prompted us to study the current situation of the infections caused by this microorganism. This study presents a survey on the frequency of infections, serotype distribution, and susceptibility to antimicrobial agents of group B streptococcal isolates in the Sharon district (Israel). It seems that the transformation of the group B streptococci to human pathogens has also affected this area.