Antibiotic resistance of Streptococcus agalactiae isolated from pregnant women in Garankuwa, South Africa

Abstract

BackgroundThis 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.MethodsThe 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.ResultsOut 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 (MLSB), 17.4 % had inducible MLSB. 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.ConclusionsThe 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.

Cross-resistance to lincosamides, streptogramins A and pleuromutilins in Streptococcus agalactiae isolates from the USA

“…7–12,37 Among our isolates, lnu (B) is invariably present in combination with lsa (E) on the same transposable element, as previously described in S. aureus 15 and GBS, 33 and in association with cross-resistance to clindamycin, virginiamycin M1 and tiamulin (LSAP). The MIC values against virginiamycin M1 and tiamulin for these isolates positive for both lnu (B) and lsa (E) were up to 4-fold and 16-fold higher, respectively.…”

“…While they still remain relatively rare, the frequency of these resistance phenotypes appears to have increased in the last decade, both in the ABCs collection and in other reports in the literature. 7–12,17,18,37 …”

“…In contrast, resistance specific to lincosamides (L phenotype) is rare in GBS, but has been previously reported in clinical isolates from Canada, 7 the United States, 8 Spain, 9 Argentina, 10 Korea 11 and South Africa, 12 due to antibiotic modification mediated by the lnu (B) gene. Members of the lnu (previously lin ) gene family encode nucleotidyltransferase enzymes that catalyse the adenylation of lincomycin and clindamycin; lnu (B) was first identified in Enterococcus faecium , 13 and later in GBS, 7 Streptococcus uberis , 14 Staphylococcus aureus 15 and Streptococcus lutetiensis .…”

In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

“…In the present work, consistent with such investigations (GUÉRIN-FAUBLÉE et al, 2002;MINST et al, 2012;RATO et al, 2013), most isolates (96.6%) were susceptible to penicillin, indicating that this antibiotic is a viable option for the treatment of mastitis. In humans, penicillin is the recommended first-line treatment for S. agalactiae infections for all age groups, in addition to being administered prophylactically to pregnant women (BOLUKAOTO et al, 2015;VERANI et al, 2010).…”

Semina: Ciências Biológicas e da Saúde, Londrina, v. 39, n.1, jan./jun. 2018

“…In African countries, rates of erythromycin and clindamycin resistance ranging from 6.5% to 21.1% and 3.2% to 17.2%, respectively, were reported among GBS isolates from pregnant women. (11,28) Data from North America reported rates of resistance to erythromycin and clindamycin ranging from 27.4% to 36% and 27.4% to 33%, respectively. (11,29) High rates of GBS resistance for both antimicrobials were reported in Italy (32.2% for erythromycin and 43.8% for clindamycin) (30) and China (78.6% for erythromycin and 64.3% for clindamycin) (WANG et al, 2015).…”