Antibiotic resistance of Streptococcus agalactiae isolated from pregnant women in Garankuwa, South Africa.
BACKGROUND
This study was undertaken to determine the susceptibility profile and the mechanism of antibiotic resistance in Group B streptococcus (GBS) isolates detected in vaginal and rectal swabs from pregnant women attending Dr George Mukhari Academic Hospital, a University Teaching Hospital in Pretoria, South Africa.


METHODS
The samples were collected over an 11-month period, cultured on selective media (colistin and nalidixic acid agar and Todd-Hewitt broth), and GBS positively identified by using different morphological and biochemical tests. The susceptibility testing was done using the Kirby-Bauer and E test methods according to CLSI guidelines 2012. The D test method was used for the detection of inducible clindamycin resistance. Multiplex PCR with specific primers was used to detect different genes coding for resistance.


RESULTS
Out of 413 samples collected, 128 (30.9%) were positive with GBS. The susceptibility testing revealed that 100% of isolates were sensitive to penicillin, ampicillin, vancomycin and high level gentamicin. Erythromycin and clindamycin resistance was 21.1 and 17.2%, respectively, in which 69% had harboured constitutive macrolide, lincosamide and streptogramin B (MLS(B)), 17.4% had inducible MLS(B). The M and L phenotypes were present in 6.8% each. The methylation of target encoded by ermB genes was the commonest mechanism of resistance observed in 55% of isolates, 38% of isolates had both ermB and linB genes and efflux pump mediated by mefA genes was also distributed among the isolates.


CONCLUSIONS
The study reaffirmed the appropriateness of penicillin as the antibiotic of choice for treating GBS infection. However it identified the challenges of resistance to macrolides and lincosamides used as alternative drugs for individuals allergic to penicillin. More GBS treatment options for penicillin allergic patients need to be researched on.
Department of Life and Consumer Sciences, College of Agriculture and Environmental Science, University of South Africa, Pretoria, South Africa. jbolukaoto@gmail.com.
John Y
JY
Bolukaoto
Department of Life and Consumer Sciences, College of Agriculture and Environmental Science, University of South Africa, Pretoria, South Africa. monyamc@unisa.co.za.
Charles M
CM
Monyama
Department of Life and Consumer Sciences, College of Agriculture and Environmental Science, University of South Africa, Pretoria, South Africa. timummy2002@yahoo.com.
Martina O
MO
Chukwu
Department of Obstetrics and Gynaecology, University of Limpopo, Medunsa Campus, Pretoria, South Africa. sebotselekala@yahoo.com.
Sebotse M
SM
Lekala
Department of Microbiological Pathology, University of Limpopo, Medunsa Campus, Pretoria, South Africa. Maphoshane.Nchabeleng@ul.ac.za.
Maphoshane
M
Nchabeleng
Department of Microbiological Pathology, University of Limpopo, Medunsa Campus, Pretoria, South Africa. motlatji.maloba@nhls.ac.za.
Motlatji R B
MR
Maloba
Department of Health Sciences, School of Health and Applied Sciences, Polytechnic of Namibia, P. Bag 13388, Windhoek, Namibia. rmavenyengwa@yahoo.com.|Department of Medical Microbiology, University of Zimbabwe College of Health Sciences, Harare, Zimbabwe. rmavenyengwa@yahoo.com.
Rooyen T
RT
Mavenyengwa
Department of Life and Consumer Sciences, College of Agriculture and Environmental Science, University of South Africa, Pretoria, South Africa. lebelol@unisa.ac.za.
Sogolo L
SL
Lebelo
Department of Obstetrics and Gynaecology, University of Limpopo, Medunsa Campus, Pretoria, South Africa. Sam.Monokoane@ul.ac.za.
Sam T
ST
Monokoane
Department of Obstetrics and Gynaecology, University of Limpopo, Medunsa Campus, Pretoria, South Africa. charles4@yebo.co.za.
Charles
C
Tshepuwane
Department of Health Sciences, School of Health and Applied Sciences, Polytechnic of Namibia, P. Bag 13388, Windhoek, Namibia. srmoyo@polytechnic.edu.na.
Sylvester R
SR
Moyo
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002981:Clindamycin / Q000494:pharmacology; D019175:DNA Methylation; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004917:Erythromycin / Q000494:pharmacology; D005260:Female; D005839:Gentamicins / Q000494:pharmacology; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010406:Penicillins / Q000494:pharmacology; D011247:Pregnancy; D012007:Rectum / Q000382:microbiology; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D014621:Vagina / Q000382:microbiology; D014640:Vancomycin / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D005839:Gentamicins; D018942:Macrolides; D010406:Penicillins; D002981:Clindamycin; D004917:Erythromycin; D014640:Vancomycin