Characterization of Invasive and Colonizing Isolates of Streptococcus agalactiae in East African Adults

Abstract

Ninety-five colonizing isolates and 74 invasive isolates of Streptococcus agalactiae from Kenyan adults were characterized by using capsular serotyping and multilocus sequence typing. Twenty-two sequence types clustering into five clonal complexes were found. Data support the view that S. agalactiae isolates belonging to a limited number of clonal complexes are invasive in adults worldwide.Streptococcus agalactiae, or group B streptococcus (GBS), regarded mainly as a pathogen of neonates and pregnant women (15), is increasingly affecting nonpregnant adults (19). In adults, S. agalactiae causes skin and soft tissue infections, bacteremia, urinary tract infections, pneumonia, osteomyelitis, meningitis, endocarditis, and streptococcal toxic shock syndrome (2,6,18,20). Risk factors associated with invasive GBS in adults are old age, diabetes mellitus, neurologic diseases, cirrhosis or other liver diseases, stroke, breast cancer, and renal failure (7,22,23). S. agalactiae colonizes the lower gastrointestinal and genitourinary tracts of 30 to 50% of healthy adults (26), and an estimated 20 to 30% of all pregnant women are carriers (25). S. agalactiae can be isolated from vaginal or rectal swabs, and prenatal screening for colonization of pregnant women is recommended (27). The objective of this study was to analyze the epidemiology of GBS in East African adults by using multilocus sequence typing (MLST) (13) and capsular serotyping (10), with a focus on investigating possible correlations between clonal complexes of GBS in invasive or colonizing isolates.The Aga Khan University Hospital in Nairobi (AKUH,N) is a tertiary care, referral university hospital in Nairobi, Kenya. GBS were cultivated at the Division of Microbiology of AKUH,N from specimens derived from both inpatients and outpatients between January 2007 and June 2010. Swabs from outreach collection points were transported in Stuart's transport medium to the hospital. Blood cultures were routinely performed using Plus-aerobic/F, Plus-anaerobic/F, and Peds Plus Bactec 9120 media (Becton Dickinson) in combination with commercially available biphasic culture medium bottles (Roche Diagnostics, France). Single GBS colonies were picked from 5% sheep blood agar plates (Oxoid, United Kingdom), and identification of GBS was performed using colony morphology, Gram staining, CAMP test, the API Streptococcus identification kit (Bio-Merieux, France), and the latex agglutination test using a bacterial meningitis kit with specific group B latex (Wellcogen kit from Remel Europe Ltd.). Antimicrobial susceptibility testing was performed, and results were interpreted according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI) (5). Streptococcus pneumoniae ATCC 49619 was used for quality control. All GBS isolates were found to be susceptible to penicillin and cephalosporin. GBS isolates analyzed here were selected according to availability of stocked isolates and accessibility of patient files. One isolate per patient was included in this study. Clinica...

Multilocus Sequence Typing Analysis of Invasive and Non-Invasive Group B Streptococcus of Hospital Origin in Malaysia

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Maternal colonization with Streptococcus agalactiae and associated stillbirth and neonatal disease in coastal Kenya

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Molecular Characteristics of Group B Streptococci Isolated from Adults with Invasive Infections in Japan

“…Although relationships between serotypes and CCs have been reported in various countries (29)(30)(31)(32)(33), the prevalence was different among the studied population.…”