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. 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. 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 (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. 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.

This study was undertaken to determine the virulence and antibiotic resistance profiles of diarrhoeagenic Escherichia coli (DEC) in environmental waters of Johannesburg, South Africa. Samples were collected and cultured on selective media. An 11-plex PCR assay was used to differentiate five DEC, namely: enteroaggregative (EAEC), enterohaemorrhagic (EHEC), enteroinvasive (EIEC), enteropathogenic (EPEC) and enterotoxigenic (ETEC). The antibiotic resistance profile of isolates was determined using the VITEK^®-2 automated system. The virulence profiles of 170 E. coli tested showed that 40% (68/170) were commensals and 60% (102/170) were pathogenic. EPEC had a prevalence of 19.2% (32/170), followed by ETEC 11.4% (19/170), EAEC 6% (10/170) and EHEC 3% (5/170). Hybrid DEC carrying a combination of simultaneously two and three pathogenic types was detected in twenty-eight and nine isolates, respectively. The antibiotic susceptibility testing showed isolates with multidrug resistance, including cefuroxime (100%), ceftazidime (86%), cefotaxime (81%) and cefepime (79%). This study highlighted the widespread occurrence of DEC and antibiotic resistance strains in the aquatic ecosystem of Johannesburg. The presence of hybrid pathotypes detected in this study is alarming and might lead to more severe diseases. There is a necessity to enhance surveillance in reducing the propagation of pathogenic and antibiotic-resistant strains in this area.

Diarrhoeagenic Escherichia coli pose a significant risk to human health. As such, determining the source(s) of these bacteria when isolated from patients with diarrhoea is an important step in disease prevention. To identify the presence of genes coding for virulence and phylogroups among E. coli isolated from children hospitalized due to diarrhoea in Limpopo Province, South Africa. E. coli isolates were identified using the VITEK-2 automated system. An 11-gene multiplex polymerase chain reaction (PCR) was used to differentiate five pathogenic types of E. coli: enteroaggregative (EAEC), enteroinvasive (EIEC), enterohaemorrhagic (EHEC), enteropathogenic (EPEC) and enterotoxigenic (ETEC). The Clermont quadruplex PCR method was used to identify phylogroups of isolates. From the 133 isolates tested, 79 were confirmed as E. coli. Of these, 19.0% (15/79) were commensals and 81.0% (64/79) were positive for at least one pathotype, of which ETEC was predominant (16.5%, 13/79), followed by EAEC (10.1%, 8/79), EPEC (7.6%, 6/79) and EHEC (2.5%, 2/79). Hybrid pathotypes were also detected and EAEC/ETEC was predominant (25.3%, 20/79). Phylogroup B2 was predominant (30.4%, 24/79), followed by phylogroup B1 (22.8%, 18/79), and phylogroups C and E (both 12.7%, 10/79). Just over 6% (5/79) of isolates were non-typable. There was a high distribution of diarrhoeagenic E. coli associated with different phylogroups among children living in Limpopo Province, South Africa. This emphasizes the importance of future monitoring of virulence and phylogroup distribution of E. coli isolates in this province in particular and in South Africa as a whole.

Background: Group B Streptococcus (GBS) is an important cause of maternal and neonatal morbidity and mortality in many parts of the world. It has been implicated in adverse pregnancy outcomes. Maternal colonization has been found to be a major risk factor for invasive neonatal GBS disease. The main objective of this study was to identify the risk factors of Group B streptococcus colonization and its effect on pregnancy outcome. Methods: This was a prospective study in which pregnant women attending antenatal clinic (ANC) at Dr George Mukhari Hospital (DGMH) were recruited. These were at least18 years old and were at 16 weeks gestation. Vaginal and rectal swabs were taken at recruitment. Follow up of mothers until six weeks post-delivery and babies until three months of age was done. Results: A total of 340 pregnant women were then investigated for GBS colonization. Out of this number, 164 (48.2%) were GBS positive. The majority of the women (62.1%) were parity 1 and 2. Group B Streptococcus colonization was significant in women who had no matric education and who were unemployed. There was a significantly higher GBS colonization in women with previous history of miscarriages and stillbirths. The proportion of HIV positive, GBS colonized women was significant at 41.5% as compared to HIV negative GBS colonized (34.7%). Eight women (4.9%) presented with premature rupture of membranes (PROM) and the duration ranged from 0.5 to 72 hours. Ten (6.1%) women had preterm deliveries. Three (1.8%) women had wound sepsis post caesarean section and one (0.6%) had endometritis post vaginal delivery. A total of 7 (24.1%) babies were GBS positive. The number of live babies delivered was 167, with 1 case of miscarriage due to severe preeclampsia. There were 2 cases of early neonatal deaths which included 1 case of sepsis whereas the other one had multiple congenital abnormalities. Conclusion: Colonization by GBS in pregnant women at DGMH was high. Maternal risk factors identified were previous history of stillbirths/miscarriages, lack of education and being HIV positive. Overall pregnancy outcome both maternal and foetal was good.

This study aimed to investigate phenotypic and genotypic characteristics of carbapenem-resistant Enterobacterales isolates (CRE) at a tertiary laboratory in South Africa. A total of 99 CRE isolates were collected between 2019 and 2021. Carbapenemase production was tested using modified carbapenem inhibitory method. Colistin susceptibility testing was performed using the ComASP™ Colistin broth microdilution method. Conventional PCR assays were conducted for detection of mcr-1 gene and common carbapenemase genes (bla_VIM, bla_NDM, bla_IMP, bla_KPC, bla_OXA-23, bla_OXA-51 and bla_OXA-48). Rep-PCR assay was conducted to determine the genetic relatedness of the study isolates. Majority of the isolates were Klebsiella pneumoniae (83%). Carbapenem resistant K. pneumoniae cluster was observed from ICU and surgical ward samples. Colistin resistance was observed in 13% (12/93) of the isolates namely, in 11 K. pneumoniae and one Enterobacter cloacae. The bla_OXA-48 (65%) was the most prevalent gene detected followed by bla_NDM (25%) and bla_VIM (22%). Several K. pneumoniae isolates concomitantly carried multiple carbapenemase genes with one isolate carry up to 5 five genes bla_VIM, bla_NDM, bla_OXA-48, bla_OXA-23 and bla_OXA-51. The mcr-1 gene was not detected in the isolates. Rep-PCR assay showed that most isolates matched cluster A (50%). The high prevalence of bla_OXA-48, bla_NDM and emerging colistin resistant isolates is of concern for patient management at this institution and needs close monitoring. Rep-PCR is a valuable tool in establishing infection clusters in resource-limited settings.

Non-O1/non-O139 Vibrio cholerae (NOVC) isolates are non-toxigenic and regarded as etiological agents of infrequent but mild-to-severe human gastroenteritis. In response to the 2022–2023 cholera outbreak in Tshwane, this study investigated the occurrence of NOVC isolates in wastewater within the Tshwane district, South Africa. A total of 341 wastewater samples were screened using Thiosulfate citrate bile salts sucrose (TCBS) media, with subsequent confirmation of Vibrio cholerae (V. cholerae) isolates by multiplex-PCR assays. Rep-PCR was performed to determine the genetic relatedness of the isolates. Selected isolates were subjected to whole genome sequencing (WGS). Of the 341 samples, PCR confirmed 143 isolates as NOVC. Genetic fingerprinting grouped these isolates into 12 distinct clusters, from which 12 representative isolates were selected for WGS and 10 isolates were confirmed as NOVC. The isolates harboured pathogenicity-related genes, such as hlyA and rtxA, as well as other genes contributing to bacterial adaptation such as trkH and tnaA. Drug resistance was mostly observed to first-line antibiotics, ciprofloxacin, chloramphenicol, and trimethoprim–sulfamethoxazole. Plasmid analysis showed six isolates harboured plasmids (pA, p21L, and PVN84) bearing multiple resistance determinants. Phylogenetic analysis showed evidence of genetic diversity amongst isolates. Although the isolates lacked classical toxigenic genes, they carried other virulence determinants associated with pathogenicity, posing a potential risk for clinical infection, highlighting the need for sustained surveillance.