Coagulase-negative staphylococci (CoNS) are increasingly associated with nosocomial infections, especially among the immunocompromised and those with invasive medical devices, posing a significant concern. We report on clinical multidrug-resistant CoNS from the uMgungundlovu District, KwaZulu-Natal Province, South Africa, as emerging pathogens. One hundred and thirty presumptive CoNS were obtained from blood cultures. Culture, biochemical tests, and the Staphaurex™ Latex Agglutination Test were used for the initial identification of CoNS isolates; confirmation and speciation were undertaken by the VITEK 2 system. Susceptibilities of isolates against a panel of 20 antibiotics were determined using the Kirby-Bauer disk diffusion method, and the multiple antibiotic resistance (MAR) indices of the isolates were determined. The polymerase chain reaction (PCR) was used to amplify the mecA gene to confirm methicillin resistance. Overall, 89/130 presumptive CoNS isolates were confirmed as CoNS by the VITEK 2 system. Of these, 68 (76.4%) isolates were putatively methicillin-resistant by the phenotypic cefoxitin screen test and 63 (92.6%) were mecA positive. Staphylococcus epidermidis (19.1%), S. hominis ssp. hominis (15.7%), and S. haemolyticus (16.9%) were the most common CoNS species. Isolates showed high percentage resistance against penicillin (100.0%), erythromycin (74.2%), and azithromycin (74.2%) while displaying high susceptibilities to linezolid (95.5%), gentamicin (95.5%), and tigecycline (94.4%). Multidrug resistance (MDR) was observed in 76.4% of isolates. MAR index calculation revealed 71.9% of isolates with MAR index >0.2 and 20.2% >0.5. Isolates with the highest MAR indices (0.7 and 0.8) were recovered from the neonatal intensive care unit. Fifty-one MDR antibiograms were observed. The high prevalence of methicillin resistance and multidrug resistance in several species of CoNS necessitates surveillance of this emerging pathogen, currently considered a contaminant of microbial cultures.

The work aims to investigate biofilm formation and biofilm/adhesion-encoding genes in coagulase-negative staphylococci (CoNS) species recovered from blood culture isolates. Eighty-nine clinical CoNS were confirmed using the VITEK 2 system, and antibiotic susceptibility testing of isolates was conducted using the Kirby-Bauer disk diffusion method against a panel of 20 antibiotics. Isolates were qualitatively screened using the Congo red agar medium. Quantitative assays were performed on microtiter plates, where the absorbances of the solubilised biofilms were recorded as optical densities and quantified. In all, 12.4% of the isolates were strong biofilm formers, 68.5% had moderate biofilm capacity, and 17.9% showed weak capacity. A subset of 18 isolates, mainly methicillin-resistant S. epidermidis, were investigated for adherence-related genes using whole-genome sequencing and bioinformatics analysis. The highest antibiotic resistance rates for strongly adherent isolates were observed against penicillin (100%) and cefoxitin (81.8%), but the isolates showed no resistance to linezolid (0.0%) and tigecycline (0.0%). The icaABC genes involved in biofilm formation were detected in 50% of the screened isolates. Other adherence-related genes, including autolysin gene atl (88.8%), elastin binding protein gene ebp (94.4%), cell wall-associated fibronectin-binding protein gene ebh (66.7%), clumping factor A gene clfA (5.5%), and pili gene ebpC (22.2%) were also found. The insertion sequence IS256, involved in biofilm formation, was found in 10/18 (55.5%) screened isolates. We demonstrate a high prevalence of biofilm-forming coagulase-negative staphylococci associated with various resistance phenotypes and a substantial agreement between the possession of biofilm-associated genes and the biofilm phenotype.

Background and Aims: Multidrug‐resistant (MDR) pathogens, particularly members of the ESKAPE group and Escherichia coli (collectively referred to as ESKAPEEc), are major contributors to bloodstream infections (BSIs) and pose significant treatment challenges. This study aimed to characterize the antimicrobial resistance (AMR) profiles of ESKAPEEc isolates from BSIs in public hospitals in the uMgungundlovu District, South Africa, and to assess their resistance to World Health Organization (WHO) Access, Watch, and Reserve (AWaRe) antibiotics. Methods: Between November 2017 and December 2018, blood samples ( n = 195) were collected from adult and paediatric patients with suspected BSIs. Isolates were identified using the VITEK 2 system and confirmed by polymerase chain reaction (PCR). Antimicrobial susceptibility testing was performed using the Kirby–Bauer disk diffusion method and interpreted according to EUCAST/CLSI guidelines. The multiple antibiotic resistance index (MARI) was calculated. One‐way analysis of variance (ANOVA) was used to assess associations between MARI and clinical variables, including ward type and facility level. Results: Out of 195 presumptive isolates, 159 were confirmed as ESKAPEEc. The most frequently identified pathogens were Klebsiella pneumoniae (28.9%) and Staphylococcus aureus (28.3%). High resistance rates were observed across WHO Access and Watch antibiotics, including ampicillin (76% in E. coli ), gentamicin (67.4% in K. pneumoniae ), and ciprofloxacin (≥ 60% in most species). Carbapenem resistance in Acinetobacter baumannii reached 90%. Overall, 94.9% of isolates were MDR, and 93.1% had MARI ≥ 0.2. Significant differences in MARI values were observed across ward groups and facility levels, with the highest values recorded in intensive care units (mean = 0.67, 95% CI: 0.62–0.72) and tertiary hospitals (mean = 0.64, 95% CI: 0.60–0.68), compared to regional hospitals (mean = 0.52, 95% CI: 0.47–0.57). Conclusion: The findings reveal a high burden of MDR ESKAPEEc in BSIs and widespread resistance to WHO Watch antibiotics. Targeted antimicrobial stewardship and the implementation of microbiology‐guided therapy are urgently needed to optimize patient outcomes and curb the spread of resistance.

Staphylococcus aureus is an opportunistic human pathogen and a leading cause of bloodstream infections. It can acquire different antibiotic resistance genes, leading to treatment failure. Aim: We elaborate on the genomic characteristics; antibiotic resistance, virulence, pathogenicity, phylogenomics and clonal diversity of S. aureus implicated in bloodstream infections. Six multidrug-resistant (MDR) S. aureus, three methicillin-resistant S. aureus (MRSA) and three methicillin-sensitive S. aureus obtained from blood cultures underwent whole genome sequencing and bioinformatics analysis. All isolates carried different permutations and combinations of resistance genes including, blaZ, mecA, aac(6')-aph (2''), ant(9)-Ia, ant(6)-Ia, mepR, fosB, norA, norC, lmrS, arlS, arlR, mgrA, kdpD and sdrM. We found 6 spa types (t9475, t355, t045, t1265, t1257, and t7888) with varying profiles of virulence genes responsible for immune invasion, enterotoxins, adhesion/biofilm, haemolysins, and leukotoxins. Panton-Valentine leukocidin (Luk-PV) was found in one MSSA isolate. Two SCCmec types IVd(2B) and I(1B) were identified. Isolates belonged to four multilocus sequence types (MLSTs), the most common of which was ST5 (n=3). The STs were clustered into two clonal complexes CC5 and CC8. We found two MRSA clones typed as ST5-CC5-t045-SCCmec_I(1B), and the human-associated MRSA endemic clone ST612-CC8-t1257-SCCmec_IVd(2B). The insertion sequences IS30 and IS6 associated with virulence were found in two isolates. The presence of virulent MDR S. aureus in bloodstream infections poses a clinical concern because of limited treatment options and increased risk of mortality.