Potentially pathogenic Escherichia coli from household water in peri-urban Ibadan, Nigeria.

Feco-orally transmitted infectious diseases are common in Nigeria where the potable water access is poor. In the south-western Nigerian Ibadan metropolis, supply of municipal water is meagre as residents depend on household wells and boreholes. The likelihood of fecal contamination of household water sources in Ibadan was examined longitudinally to quantify and understand its impact. Well and borehole water samples aseptically collected from 96 households in Ibadan were assessed for total heterotrophic counts (THCs), total coliform counts (TCCs) and total Escherichia coli counts (TECs) using a pour plate technique. E. coli were identified by uidA and whole-genome sequencing using Illumina technology, whereas virulence factors were predicted using VirulenceFinder. There was season-independent abundance of THC and TCC in the well and borehole with a significant recovery of E. coli in the wells during the wet season compared to the dry season (P = 0.0001). Virulence genes associated with pathogenic E. coli were identified in 13 (52%) strains with one E. coli each classified as extra-intestinal E. coli, avian pathogenic E. coli and enteroaggregative E. coli. High heterotrophic and coliform counts, with rainfall-driven E. coli contamination revealed that the water sources evaluated in this study are unfit for consumption.

ε-Caprolactam Utilization by Proteus sp. and Bordetella sp. Isolated From Solid Waste Dumpsites in Lagos State, Nigeria, First Report.

The ε-caprolactam is the monomer of the synthetic non-degradable nylon-6 and often found as nonreactive component of nylon-6 manufacturing waste effluent. Environmental consequences of its toxicity to natural habitats and humans pose a global public concern. Soil samples were collected from three designated solid waste dumpsites, namely, Abule-Egba, Olusosun and Isheri-Igando in Lagos State, Nigeria. Sixteen bacteria isolated from these samples were found to utilize the ε-caprolactam as a sole source of carbon and nitrogen at concentration of ≤20 g l(-1). The isolates were characterized using their 16S rRNA gene sequence and showed similarity with Pseudomonas sp., Proteus sp., Providencia sp., Corynebacterium sp., Lysinibacillus sp., Leucobacter sp., Alcaligenes sp. and Bordetella sp. Their optimal growth conditions were found to be at temperature range of 30 to 35 °C and pH range of 7.0-7.5. High Performance liquid chromatography analysis of the ε-caprolactam from supernatant of growth medium revealed that these isolates have potential to remove 31.6-95.7 % of ε-caprolactam. To the best of our knowledge, this study is first to report the ability of Proteus sp. and Bordetella sp. for ε-caprolactam utilization.

Environmental impact assessment of Attenda abattoir, Ogbomoso southwestern Nigeria on surface and groundwater quality using geo-electrical imaging and microbiological analysis.

The impact of Attenda abattoir, Ogbomoso southwestern Nigeria on four water sources was investigated using geoelectrical imaging and microbiological analysis. 2D electrical resistivity imaging indicated groundwater contamination by leachate from the abattoir. Electrical resistivity values measured by the traverse run directly on the waste dump and other areas impacted by the waste from the abattoir are generally very low (6.68-16.7 Ωm) in comparison to other positions (135-288 Ωm). The total viable bacteria count of the water samples ranged from 0.49 × 10(6) to 2.85 × 10(8) cfu/ml and all samples are contaminated with coliforms with the most probable number (MPN)/100 ml ranging from 110 to ≥ 1,600 MPN/100 ml. Among bacteria isolated from the study site (n = 95), resistance to eight antibiotics ranged from 35.8% to 94%. In addition, 85% of Streptococcus agalactiae (n = 31) and Staphylococci (n = 9) showed haemolytic activity while 92% of all isolates showed ß-lactamase activity. These results suggest that operations of the abattoir may impact negatively on surrounding aquatic ecosystem and endanger the health of surrounding residents who use water from the wells for domestic purposes. Furthermore, such aquatic ecosystems may serve as reservoir of antibiotic resistant bacteria.

blaNDM-1-producing Vibrio parahaemolyticus and V. vulnificus isolated from recreational beaches in Lagos, Nigeria.

Twenty-six strains of Vibrio parahaemolyticus and 14 strains of V. vulnificus isolated from selected beaches in Lagos State, Nigeria, were examined for virulence and antimicrobial resistance genes. The V. parahaemolyticus isolates were further serotyped and subjected to pulsed field gel electrophoresis (PFGE). Five strains of V. vulnificus and one of V. parahaemolyticus carried the New Delhi-metallo-beta-lactamase gene blaNDM-1, seven strains carried blaTEM, and four strains of V. vulnificus and one of V. parahaemolyticus carried blaCMY. Real-time PCR assay for detection of virulence genes tdh and trh in the V. parahaemolyticus isolates showed that five isolates were positive for tdh, two for trh, and one isolate carried both genes. Ten V. parahaemolyticus serogroups and 23 pulsotypes were identified from 26 isolates based on O and K antigens typing and PFGE. Five of the isolates belong to the pandemic strains O1:Kut and O3:K6, and three belonged to the highly virulent O4:Kut serotype. Nineteen of the isolates showed distinct PFGE banding patterns. These results highlighted the importance of Nigerian recreational beaches as reservoirs of antimicrobial resistance genes of global public health interest, such as blaNDM-1.

Extended Spectrum Beta-Lactamase (ESBL)-producing bacteria isolated from hospital wastewaters, rivers and aquaculture sources in Nigeria.

Untreated wastewater is a risk factor for the spread of antibiotic resistance in the environment. However, little is known about the contribution of untreated wastewater to the burden of antibiotic resistance in the Nigerian environment. In this study, a total of 143 ceftazidime-/cefpodoxime-resistant bacteria isolated from untreated wastewater and untreated wastewater-contaminated surface and groundwater in Nigeria were screened for extended-spectrum ß-lactamase (ESBL) genes, integrons and integron gene cassettes by PCR. The genetic environment of bla CTX-M-15 was mapped by PCR and potentially conjugative plasmids were detected among the isolates by degenerate primer MOB typing (DPMT). ESBL production was confirmed in 114 (79.7%) isolates and ESBL genes (bla SHV, bla CTX-M-15 and bla TEM) were detected in 85 (74.6%) ESBL-producing isolates. bla CTX-M-15 was associated with ISEcp1 and with orf477 in 12 isolates and with ISEcp1, IS26 and orf477 in six others. To the best of our knowledge, this is the first report of bla CTX-M-15 in hand-dug wells and borehole serving as sources of drinking water and a first report of the genetic environment of bla CTX-M-15 in environmental bacteria from Nigeria. The results of this study confirm untreated wastewater as an important medium for the spread of ESBL-producing bacteria within the Nigerian environment. Hence, the widespread practice of discharging untreated wastewater into the aquatic ecosystem in Nigeria is a serious risk to public health.

Worldwide emergence of colistin resistance in Klebsiella pneumoniae from healthy humans and patients in Lao PDR, Thailand, Israel, Nigeria and France owing to inactivation of the PhoP/PhoQ regulator mgrB: an epidemiological and molecular study.

The emergence of colistin-resistant Klebsiella pneumoniae (CRKP) is a major public health concern worldwide. In this study, the prevalence and molecular basis of colistin resistance in CRKP isolated from healthy individuals and patients in Lao PDR, Thailand, Nigeria and France were investigated. Stool samples were screened by culture for the presence of colistin-resistant Klebsiella spp. Whole-genome sequence analysis was used to decipher the molecular mechanism of colistin resistance in a blaNDM-1-positive in vitro-selected CRKP mutant. PCR amplification and sequencing of the mgrB genetic environment was performed for all CRKP isolates as well as control colistin-susceptible K. pneumoniae (CSKP) isolates recovered from the same stools. A total of 869 stool samples were screened for colistin-resistant Klebsiella spp., yielding 32 CRKP and 2 colistin-resistant Klebsiella oxytoca. Comparative whole-genome sequence analysis revealed that an in vitro-selected CRKP mutant had an insertion sequence in its mgrB gene, as well as missense mutations in other selected clones. Of the 34 colistin-resistant Klebsiella spp. isolates, 14 (41.2%; 13 CRKP and 1 K. oxytoca) from the four countries also had various defects in their mgrB genes, but no such defects were found in the CSKP controls (P<10(-4)). Few mutations were observed in pmrAB compared with mgrB among the CRKP isolates. The worldwide emergence of CRKP is a major public health concern. Detection and surveillance of such strains are warranted to prevent an uncontrollable pandemic. Inactivation of the PhoP/PhoQ regulator gene mgrB is associated with ≥40% of colistin resistance among the CRKP isolates observed in this study.