Larry Chikwelu Obi

Occurrence of potentially pathogenic vibrios in final effluents of a wastewater treatment facility in a rural community of the Eastern Cape Province of South Africa.

We assessed the occurrence of Vibrio pathogens in the final effluents of a rural wastewater treatment facility in the Eastern Cape Province of South Africa as free or plankton-associated (180 microm, 60 microm and 20 microm plankton sizes) entities using standard culture-based and molecular techniques. The free-living Vibrio densities varied from 0 to 3.45 x 10(1) cfu ml(-1), while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 microm (0-4.50 x 10(3) cfu ml(-1)); 60 microm (0-4.86 x 10(3) cfu ml(-1)); 20 microm (0-1.9 x 10(5) cfu ml(-1)). The seasonal variations in the Vibrio densities in the 180 and 60 microm plankton size samples were significant (p < 0.05), while the 20 microm plankton size and free-living Vibrio densities were not. Molecular confirmation of the presumptive vibrios isolates revealed fluvialis (36.5%), as the predominant species, followed by Vibrio vulnificus (34.6%), and Vibrio parahaemolyticus (23.1%); only API 20NE was employed to detect Vibrio metschnikovii (5.8%), suggesting a high incidence of pathogenic Vibrio species in the final effluent of the rural wastewater facility. Analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (p < 0.001 and p < 0.002 respectively) as well as with pH and turbidity (p < 0.001) in the final effluent. We conclude that rural wastewater treatment facilities in the Eastern Cape Province of South Africa are potential sources of Vibrio pathogens in the aquatic environment of the communities.

Multiple antibiotic resistances among Shiga toxin producing Escherichia coli O157 in feces of dairy cattle farms in Eastern Cape of South Africa

BackgroundShiga toxin–producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of bloody diarrhea and hemolytic-uremic syndrome (HUS). The ability of STEC strains to cause human disease is due to the production of Shiga toxins. The objectives of this study were to determinate the prevalence, serotypes, antibiotic susceptibility patterns and the genetic capability for Shiga toxin production in Escherichia coli (STEC) strains isolated from dairy cattle farms in two rural communities in the Eastern Cape Province of South Africa. MethodsFecal samples were collected between March and May 2014, from individual cattle (nu2009=u2009400) in two commercial dairy farms having 800 and 120 cattle each.Three hundred presumptive isolates obtained were subjected to polymerase chain reactions (PCR) for identification of O157 serogroup and Shiga toxin producing genes (stx1, stx2) on genomic DNA extracted by boiling method. Susceptibility of the isolates to 17 antibiotics was carried out in vitro by the standardized agar disc-diffusion method. Results Based on direct PCR detection, 95 (31.7xa0%) isolates were identified as O157 serogroup. The genetic repertoire for Shiga toxin production was present in 84 (88.42xa0%) isolates distributed as stx1 (37), stx2 (38) and stx1/2 (9) respectively while 11 of the isolates did not harbor Shiga toxin producing genes. Multiple antibiotic resistances were observed among the isolates and genetic profiling of resistance genes identified blaampC 90xa0%, blaCMY 70xa0%, blaCTX-M 65xa0%, blaTEM 27xa0% and tetA 70xa0% and strA 80xa0% genes among the antimicrobial resistance determinants examined.ConclusionWe conclude that dairy cattle farms in the Eastern Cape Province are potential reservoirs of antibiotic resistance determinants in the province.

Antibiotic Susceptibilities of Enterococcus Species Isolated from Hospital and Domestic Wastewater Effluents in Alice, Eastern Cape Province of South Africa

Background: Antimicrobial resistance in microorganisms are on the increase worldwide and are responsible for substantial cases of therapeutic failures. Resistance of species of Enterococcus to antibiotics is linked to their ability to acquire and disseminate antimicrobial resistance determinants in nature, and wastewater treatment plants (WWTPs) are considered to be one of the main reservoirs of such antibiotic resistant bacteria. We therefore determined the antimicrobial resistance and virulence profiles of some common Enterococcus spp that are known to be associated with human infections that were recovered from hospital wastewater and final effluent of the receiving wastewater treatment plant in Alice, Eastern Cape. Methods: Wastewater samples were simultaneously collected from two sites (Victoria hospital and final effluents of a municipal WWTP) in Alice at about one to two weeks interval during the months of July and August 2014. Samples were screened for the isolation of enterococci using standard microbiological methods. The isolates were profiled molecularly after targeted generic identification and speciation for the presence of virulence and antibiotic resistance genes. Results: Out of 66 presumptive isolates, 62 were confirmed to belong to the Enterococcus genusof which 30 were identified to be E. faecalis and 15 E. durans. The remaining isolates were not identified by the primers used in the screening procedure. Out of the six virulence genes that were targeted only three of them; ace, efaA, and gelE were detected. There was a very high phenotypic multiple resistance among the isolates and these were confirmed by genetic analyses. Conclusions: Analyses of the results obtained indicated that hospital wastewater may be one of the sources of antibiotic resistant bacteria to the receiving WWTP. Also, findings revealed that the final effluent discharged into the environment was contaminated with multi-resistant enterococci species thus posing a health hazard to the receiving aquatic environment as these could eventually be transmitted to humans and animals that are exposed to it.

Municipal wastewater effluents as a source of listerial pathogens in the aquatic milieu of the Eastern Cape Province of South Africa: a concern of public health importance.

We evaluated the effluent quality of an urban wastewater treatment facility in South Africa and its impact on the receiving watershed for a period of 12 months. The prevalence and antimicrobial susceptibility of potential Listeria pathogens (L. ivanovii and L. innocua) and the physicochemical quality of the treated wastewater effluent was assessed, with a view to ascertain the potential health and environmental hazards of the discharged effluent. Total listerial density varied between 2.9 × 100 and 1.2 × 105 cfu/mL; free living Listeria species were more prevalent (84%), compared to Listeria species attached to planktons (59–75%). The treated effluent quality fell short of recommended standards for turbidity, dissolved oxygen, chemical oxygen demand, nitrite, phosphate and Listeria density; while pH, temperature, total dissolved solids and nitrate contents were compliant with target quality limits after treatment. The Listeria isolates (23) were sensitive to three (15%) of the 20 test antibiotics, and showed varying (4.5–91%) levels of resistance to 17 antibiotics. Of seven resistance gene markers assayed, only sulII genes were detected in five (22%) Listeria strains. The study demonstrates a potential negative impact of the wastewater effluent on the receiving environment and suggests a serious public health implication for those who depend on the receiving watershed for drinking and other purposes.

Virulence and antimicrobial resistance factors of Enterococcusspp. isolated from fecal samples from piggery farms in Eastern Cape, South Africa

BackgroundEnterococci have emerged as an important opportunistic pathogen causing life-threatening infections in hospitals. The emergence of this pathogen is associated with a remarkable capacity to accumulate resistance to antimicrobials and multidrug-resistance particularly to vancomycin, erythromycin and streptomycin have become a major cause of concern for the infectious diseases community. In this paper, we report the prevalence of Enterococcus in respect to species distribution, their virulence and antibiogram profiles.MethodsFour hundred fecal samples were collected from two piggery farms in the Eastern Cape Province of South Africa. Enterococcus species were isolated and confirmed with generic specific primers targeting the tuf gene (encoding elongation factor). The confirmed isolates were speciated with enterococci species specific primers that aimed at delineating them into six species that are commonly associated with infections in humans. Antibiotic susceptibility testing was performed by disc diffusion method. Six virulence genes and antimicrobial resistance profiles of the isolates were evaluated molecularly.ResultsMolecular identification of the presumptive isolates confirmed 320 isolates as Enterococcus spp. Attempt at speciation of the isolates with primers specific for E. faecalis, E. durans, E. casseliflavus, E. hirae and E. faecium delineated them as follows: E. faecalis (12.5xa0%), E. hirae (31.25xa0%), E. durans (18.75xa0%) and E. faecium (37.5xa0%) while E. casseliflavus was not detected. All the isolates were resistant to vancomycin, streptomycin and cloxacillin, and to at least two different classes of antibiotics, with 300 (93.8xa0%) isolates being resistant to five or more antibiotics. Also, three out of the six virulence genes were detected in majority of the isolates and they are Adhesion of collagen in E. faecalis (ace) (96.88xa0%), gelatinase (gelE) (93.13xa0%) and surface protein (esp) (67.8xa0%).ConclusionThere was high prevalence of multi-resistant vancomycin Enterococcus spp. (VREs) in the fecal samples of pigs in the farms studied, and this poses health implications as vancomycin is an important drug in human medicine. Further studies are needed to determine the spread of vancomycin resistance among bacteria of human origin in the communities.

Occurrence of virulence gene signatures associated with diarrhoeagenic and non-diarrhoeagenic pathovars of Escherichia coli isolates from some selected rivers in South-Western Nigeria

BackgroundDiarrhoeal diseases are attributable to unsafe water stemming from improper sanitation and hygiene and are reportedly responsible for extensive morbidity and mortality particularly among children in developed and developing countries.MethodsWater samples from selected rivers in Osun State, South-Western Nigeria were collected and analyzed using standard procedures. Escherichia coli isolates (n=300) were screened for 10 virulence genes using polymerase chain reaction for pathotyping.ResultsWhile the virulence gene (VG) lt for enterotoxigenic E. coli had the highest prevalence of 45xa0%, the enteropathogenic E. coli genes eae and bfp were detected in 6 and 4xa0% of the isolates respectively. The VGs stx1 and stx2 specific for the enterohemorrhagic E. coli pathotypes were detected in 7 and 1xa0% of the isolates respectively. Also, the VG eagg harboured by enteroaggregative pathotype and diffusely-adherent E. coli VG daaE were detected in 2 and 4xa0% of the isolates respectively and enteroinvasive E. coli VG ipaH was not detected. In addition, the VGs papC for uropathogenic and ibeA for neonatal meningitis were frequently detected in 19 and 3xa0% of isolates respectively.ConclusionsThese findings reveal the presence of diarrhoeagenic and non-diarrhoeagenic E. coli in the selected rivers and a potential public health risk as the rivers are important resources for domestic, recreational and livelihood usage by their host communities.

Detection of potential risk of wastewater effluents for transmission of antibiotic resistance from Vibrio species as a reservoir in a peri-urban community in South Africa

We assessed the antibiogram characteristics of some Vibrio species isolated from wastewater final effluents in a typical peri-urban community of South Africa. Marked resistances were noted against erythromycin (100%), chloramphenicol (100%), nitrofurantoin, cefuroxime and cephalothin (90–95%) in V. parahaemolyticus, V. fluvialis and V. vulnificus, respectively. Fourteen antibiotypes were identified, with multiresistance to 8–10 antibiotics being common. The antibiotypes AMP, PEN, STR, SUL, TMP, COT, CHL, ERY, CIP and PB demonstrated by V. fluvialis were the most prevalent (17.24%). Eight putative antibiotic resistance genes were identified with floR being the mostly (100%) detected in all the three species while tet(A) was the least with 65% prevalence in V. vulnificus, 7.14% in V. parahaemolyticus and none in V. fluvialis. These results demonstrate that the treated effluent system are reservoirs for various antibiotic resistance genes which could be disseminated to inhabitants downstream the plant and pose health risk to the communities who are dependent upon the watershed for domestic and recreational purposes.

Multiple antibiotic resistance indexing of Escherichia coli to identify high-risk sources of faecal contamination of water

We evaluated the antibiogram profile of Escherichia coli (nu2009=u2009300) isolated from selected rivers in Osun State, Nigeria. The identities of the E. coli isolates were confirmed by polymerase chain reaction (PCR) technique. Susceptibility of the isolates to 20 antibiotics conventionally used in clinical cases was assessed in vitro by the standardized agar disc-diffusion method. All the isolates were susceptible to imipenem, meropenem, amikacin and gatilofloxacin. The isolates were variously susceptible to the other antibiotics as follows: ciprofloxacin (96xa0%), kanamycin (95xa0%), neomycin (92xa0%), streptomycin (84xa0%), chloramphenicol (73xa0%), nalidixic acid (66xa0%), nitrofurantoin (64xa0%), gentamycin (63xa0%), doxycycline (58xa0%), cefepime (57xa0%), tetracycline (49xa0%) and cephalothin (42xa0%). The multiple antibiotic resistance indexing ranged from 0.50 to 0.80 for all the sampling locations and exceeded the threshold value of 0.2, suggesting the origin of the isolates to be of high antimicrobial usage. Our findings signify an increase in the incidence of antimicrobial resistance of E. coli towards conventionally used antibiotics necessitating proper surveillance programmes towards the monitoring of antimicrobial resistance determinants in water bodies.

Antimicrobial resistance determinants of Escherichia coli isolates recovered from some rivers in Osun State, South-Western Nigeria: Implications for public health.

The inevitable development of resistance has sunk the great success achieved in the discovery of antimicrobial agents and dashed the hope of man in the recovery from infections and illnesses, as diseases and disease agents that were once thought to be controlled by antimicrobials are now re-emerging in new leagues resistance to therapy. A total of 300 PCR confirmed Escherichia coli isolates recovered from different river sources in Osun State, Nigeria were evaluated for their antibiogram profiling by the disc diffusion method and the resistant isolates were further profiled for their genotypic antimicrobial resistance determinants by polymerase chain reaction assays. Among the 20 antimicrobials selected from 10 families, resistance among sulfonamides, β-lactams and tetracyclines were found to be most frequent than phenicols and aminoglycosides with a noticeable increase in the number of multi-drug resistance ranging from three to nine antimicrobials. A total of 19 resistance determinants were assessed with their prevalence and distributions obtained as follows; [sulfonamides sulI (8%), sulII (41%)], [β-lactams; ampC 22%; blaTEM, (21%), and blaZ (18%),], [tetracyclines tetA (24%), tetB (23%), tetC (18%), tetD (78%), tetK (15%), and tetM, (10%)], [phenicols; catI (37%), catII (28%), and cmIA1 (19%)] and [aminoglycosides; aacC2 (8%), aphA1 (80%), aphA2 (80%), aadA (79%) and strA (38%)]. The Pearson chi-square exact test revealed many strong significant associations among ampC, blaTEM, blaZ and tetA genes with some determinants screened. The findings signify high increase in the prevalence of multidrug resistant E. coli isolates and resistance determinants indicating increased public health risks associated with the ingestion of waters from untreated sources. Hence, a necessity for safe water supply, provision of proper sanitation facilities and good surveillance programmes to monitor antimicrobial resistance patterns in water bodies.

Occurrence of non-O157 Shiga toxin-producing Escherichia coli in two commercial swine farms in the Eastern Cape Province, South Africa

Shiga toxin-producing Escherichia coli (STEC) is one of the most significant causes of food-borne infections capable of causing serious health complications in humans. Even though ruminants are known to be the major reservoirs of STEC, other non-ruminant food producing animals may also harbour pathogenic E. coli strains. In this study, we investigated the prevalence of E. coli serogroups O26, O111, O121, O145, and O157 and their associated virulence genes (stx1, stx2, eae, and ehxA) in swine faecal samples obtained from the two major commercial farms located in the Nkonkobe Municipality, Eastern Cape, South Africa. The proportions of serogroups detected were O26; 35 (7%), O145; 14 (2.8%), and O157:H7; 43 (8.6%) of the total animals sampled. Out of the 500 animals sampled, 22 isolates of E. coli (1.4%) tested positive for the stx2 gene, and 7 of these isolates belonged to E. coli O26 serogroup, while the remaining 15 most likely belonged to serogroups untargeted in this study. Other virulence genes (stx1, eae, and ehxA) that we screened for were not detected. These findings reveal that pigs within the Eastern Cape Province of South Africa can harbour Shiga toxin-producing E. coli.