Background: Resistance of Staphylococcus aureus to commonly used antibiotics is linked to their ability to acquire and disseminate antimicrobial-resistant determinants in nature, and the marine environment may serve as a reservoir for antibiotic-resistant bacteria. This study determined the antibiotic sensitivity profile of S. aureus isolated from selected beach water and intertidal beach sand in the Eastern Cape Province of South Africa. Methods: Two hundred and forty-nine beach sand and water samples were obtained from 10 beaches from April 2015 to April 2016. Staphylococcus aureus was isolated from the samples using standard microbiological methods and subjected to susceptibility testing to 15 antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA) was detected by susceptibility to oxacillin and growth on Brilliance MRSA II agar. Antibiotic resistance genes including mecA, femA rpoB, blaZ, ermB, ermA, ermC, vanA, vanB, tetK and tetM were screened. Results: Thirty isolates (12.3%) were positive for S. aureus by PCR with over 50% showing phenotypic resistance to methicillin. Resistance of S. aureus to antibiotics varied considerably with the highest resistance recorded to ampicillin and penicillin (96.7%), rifampicin and clindamycin (80%), oxacillin (73.3%) and erythromycin (70%). S. aureus revealed varying susceptibility to imipenem (96.7%), levofloxacin (86.7%), chloramphenicol (83.3%), cefoxitin (76.7%), ciprofloxacin (66.7%), gentamycin (63.3%), tetracycline and sulfamethoxazole-trimethoprim (56.7%), and vancomycin and doxycycline (50%). All 30 (100%) S. aureus isolates showed multiple antibiotic-resistant patterns (resistant to three or more antibiotics). The mecA, femA, rpoB, blaZ, ermB and tetM genes were detected in 5 (22.7%), 16 (53.3%), 11 (45.8%), 16 (55.2%), 15 (71.4%), and 8 (72.7%) isolates respectively; Conclusions: Results from this study indicate that beach water and sand from the Eastern Cape Province of South Africa may be potential reservoirs of antibiotic-resistant S. aureus which could be transmitted to exposed humans and animals.

Listeria species are Gram-positive, rod-shaped, facultative anaerobic bacteria, which do not produce endospores. The genus, Listeria, currently comprises 17 characterised species of which only two (L. monocytogenes and L. ivanovii) are known to be pathogenic to humans. Food products and related processing environments are commonly contaminated with pathogenic species. Outbreaks and sporadic cases of human infections resulted in considerable economic loss. South Africa witnessed the world’s largest listeriosis outbreak, characterised by a progressive increase in cases of the disease from January 2017 to July 2018. Of the 1060 laboratory-confirmed cases of listeriosis reported by the National Institute of Communicable Diseases (NICD), 216 deaths were recorded. Epidemiological investigations indicated that ready-to-eat processed meat products from a food production facility contaminated with L. monocytogenes was responsible for the outbreak. Multilocus sequence typing (MLST) revealed that a large proportion (91%) of the isolates from patients were sequence type 6 (ST6). Recent studies revealed a recurrent occurrence of small outbreaks of listeriosis with more severe side-effects in humans. This review provides a comparative analysis of a recently reported and most severe outbreak of listeriosis in South Africa, with those previously encountered in other countries worldwide. The review focuses on the transmission of the pathogen, clinical symptoms of the disease and its pathogenicity. The review also focuses on the major outbreaks of listeriosis reported in different parts of the world, sources of contamination, morbidity, and mortality rates as well as cost implications. Based on data generated during the outbreak of the disease in South Africa, listeriosis was added to the South African list of mandatory notifiable medical conditions. Surveillance systems were strengthened in the South African food chain in order to assist in preventing and facilitating early detection of both sporadic cases and outbreaks of infections caused by these pathogens in humans.

With the increasing spread of antimicrobial resistance, there is growing attention to the contribution made by drinking water systems. The potential health impact of two drinking water treatment and distribution systems (A and B) in the North-West Province of South Africa was determined by investigating the water quality and occurrence of antimicrobial-resistant heterotrophic bacteria and genes in the raw and treated water over four seasons. Most of the physicochemical parameters except for electrical conductivity were within permissible limits. Coliform bacteria reduced from raw to potable water except for counts higher than the threshold recorded in Summer and Winter. A total of 203 heterotrophic bacterial isolates were recovered on chromogenic R2A medium and subjected to susceptibility testing to twelve antibiotics. Most of the isolates were resistant to β-lactam antibiotics and Trimethoprim, whereas they were susceptible to Ciprofloxacin, Erythromycin, and Neomycin. The proportions of Cephalothin and Kanamycin-resistant isolates were significantly higher (p < 0.05) after treatment for site A, compared to significantly lower β-lactam, Oxytetracycline, and Trimethoprim-resistant isolates for B. Over 50% of isolates were of high risk, indicating their origin from high antibiotic-use sources. Seventy-one (35%) isolates were multidrug-resistant, out of which the majority (53.5%, n = 38) possessed the strA gene, followed by strB 21 (29.6%), dfrB 13 (18.3%), aadA 11 (15.5%), bla_CTX-M 5 (7.0%), and tetA 3 (4.2%). The 16S rRNA gene sequences of the isolates revealed strains belonging to eight bacterial families, some of which are clinically important.

Thirty-three (33) isolates of methicillin-resistantStaphylococcus aureus(MRSA) from healthy edible marine fish harvested from two aquaculture settings and the Kariega estuary, South Africa, were characterised in this study. The phenotypic antimicrobial susceptibility profiles to 13 antibiotics were determined, and their antibiotic resistance determinants were assessed. A multiplex PCR was used to determine the epidemiological groups based on the type of SCCmeccarriage followed by the detection of staphylococcal enterotoxin-encoding genessea-sedand the Panton Valentine leucocidin gene (pvl). A high antibiotic resistance percentage (67–81%) was observed for Erythromycin, Ampicillin, Rifampicin, and Clindamycin, while maximum susceptibility to Chloramphenicol (100%), Imipenem (100%), and Ciprofloxacin (94%) was recorded. Nineteen (58%) of the MRSA strains had Vancomycin MICs of ≤2 μg/mL, 4 (12%) with MICs ranging from 4–8 μg/mL, and 10 (30%) with values ≥16 μg/mL. Overall, 27 (82%) isolates were multidrug-resistant (MDR) with Erythromycin-Ampicillin-Rifampicin-Clindamycin (E-AMP-RIP-CD) found to be the dominant antibiotic-resistance phenotype observed in 4 isolates. Resistance genes such astetM,tetA,ermB,blaZ,andfemAwere detected in two or more resistant strains. A total of 19 (58%) MRSA strains possessed SCCmectypes I, II, or III elements, characteristic of healthcare-associated MRSA (HA-MRSA), while 10 (30%) isolates displayed SCCmectype IVc, characteristic of community-associated MRSA (CA-MRSA). Six (18%) of the multidrug-resistant strains of MRSA were enterotoxigenic, harbouring thesee, sea,orsecgenes. A prevalence of 18% (6/33) was also recorded for theluk-PVLgene. The findings of this study showed that marine fish contained MDR-MRSA strains that harbour SCCmectypes, characteristic of either HA-MRSA or CA-MRSA, but with a low prevalence of enterotoxin andpvlgenes. Thus, there is a need for continuous monitoring and implementation of better control strategies within the food chain to minimise contamination of fish with MDR-MRSA and the ultimate spread of the bug.

Listeriosis is a foodborne disease caused by Listeria monocytogenes species and is known to cause severe complications, particularly in pregnant women, young children, the elderly, and immunocompromised individuals. The aim of this study was to investigate the presence of Listeria species in food and water using both biochemical and species-specific PCR analysis. L. monocytogenes isolates were further screened for the presence of various antibiotic resistance, virulence, and biofilm-forming determinants profiles using phenotypic and genotypic assays. A total of 207 samples (composed of meat, milk, vegetables, and water) were collected and analyzed for presence of L. monocytogenes using species specific PCR analysis. Out of 267 presumptive isolates, 53 (19.85%) were confirmed as the Listeria species, and these comprised 26 L. monocytogenes, 3 L. innocua, 2 L. welshimeri, and 1 L. thailandensis. The remaining 21 Listeria species were classified as uncultured Listeria, based on 16SrRNA sequence analysis results. A large proportion (76% to 100%) of the L. monocytogenes were resistant to erythromycin (76%), clindamycin (100%), gentamicin (100%), tetracycline (100%), novobiocin (100%), oxacillin (100%), nalidixic acid (100%), and kanamycin (100%). The isolates revealed various multi-drug resistant (MDR) phenotypes, with E-DA-GM-T-NO-OX-NA-K being the most predominant MDR phenotypes observed in the L. monocytogenes isolates. The virulence genes prfA, hlyA, actA, and plcB were detected in 100%, 68%, 56%, and 20% of the isolates, respectively. In addition, L. monocytogenes isolates were capable of forming strong biofilm at 4 °C (%) after 24 to 72 h incubation periods, moderate for 8% isolates at 48 h and 20% at 72 h (p < 0.05). Moreover, at 25 °C and 37 °C, small proportions of the isolates displayed moderate (8–20%) biofilm formation after 48 and 72 h incubation periods. Biofilm formation genes flaA and luxS were detected in 72% and 56% of the isolates, respectively. These findings suggest that proper hygiene measures must be enforced along the food chain to ensure food safety.

Campylobacter jejuni (CJ) is a zoonotic microbe and a major causative organism of diarrheal infection in humans that often has its functional characteristics inactivated in stressed conditions. The current study assessed the correlation between recovered CJ and water quality parameters and the drug sensitivity patterns of the pathogen to frontline antibiotics in human and veterinary medicine. Water samples (n = 244) from rivers/estuarines were collected from April–September 2016, and physicochemical conditions were recorded on-site. CJ was isolated from the samples using standard microbiological methods and subjected to sensitivity testing to 10 antibiotics. Mean CJ counts were between 1 and 5 logs (CFU/mL). Ninety-five isolates confirmed as CJ by PCR showed varying rates of resistance. Sensitivity testing showed resistance to tetracycline (100%), azithromycin (92%), clindamycin (84.2%), clarithromycin and doxycycline (80%), ciprofloxacin (77.8%), vancomycin (70.5%), erythromycin (70%), metronidazole (36.8%) and nalidixic acid (30.5%). Virulence encoding genes were detected in the majority 80/95, 84.2%) of the confirmed isolates from cdtB; 60/95 (63.2%) from cstII; 49/95 (51.6%) from cadF; 45/95 (47.4%) from clpP; 30/95 (31.6%) from htrB, and 0/95 (0%) from csrA. A multiple resistance cmeABC active efflux pump system was present in 69/95 (72.6) isolates. The presence of CJ was positively correlated with temperature (r = 0.17), pH (r = 0.02), dissolved oxygen (r = 0.31), and turbidity (r = 0.23) but negatively correlated with salinity (r = −0.39) and conductivity (r = −0.28). The detection of multidrug resistant CJ strains from estuarine water and the differential gene expressions they possess indicates a potential hazard to humans. Moreover, the negative correlation between the presence of the pathogen and physicochemical parameters such as salinity indicates possible complementary expression of stress tolerance response mechanisms by wild-type CJ strains.