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Introduction: This study investigated the mechanisms of resistance in 36 E. coli isolated from waste, litter, soil and water samples collected from poultry farms in Southwestern Nigeria. Methodology: Minimum inhibitory concentration (MIC) distributions of the isolates were determined using the methods of the Clinical and Laboratory Standard Institute and resistance genes detected by PCR. Results: A total of 30 isolates (94%) showed resistance to more than one antimicrobial. Percentage resistance was: tetracycline 81%, sulphamethoxazole 67%, streptomycin 56%, trimethoprim 47 %, ciprofloxacin 42%, ampicillin 36%, spectinomycin 28%, nalidixic acid 25%, chloramphenicol 22%, neomycin 14%, gentamicin 8%, amoxicillin-clavulanate, ceftiofur, cefotaxime, colistin, florfenicol and apramycin 0%. Resistance genes found among the isolates include bla-TEM (85%), sul2 (67%), sul3 (17%), aadA (65%), strA (70%), strB (61%), catA1 (25%), cmlA1 (13%), tetA (21%) and tetB (17%). Class 1 and 2 integrons were found in five (14%) and six (17%) isolates, respectively, while one isolate was positive for both classes of integrons. Seven out of eight isolates with resistance to ciprofloxacin and MIC ≤ 32 mg/L to nalidixic acid contained qnrS genes. Conclusions: Our findings provided additional evidence that the poultry production environment in Nigeria represents an important reservoir of antibiotic resistance genes such as qnrS that may spread from livestock production farms to human populations via manure and water.

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 β-lactamase (ESBL) genes, integrons and integron gene cassettes by PCR. The genetic environment of bla 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, bla and bla) were detected in 85 (74.6%) ESBL-producing isolates. bla 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 in hand-dug wells and borehole serving as sources of drinking water and a first report of the genetic environment of bla 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.

Emergence of multidrug-resistant Acinetobacter baumannii producing OXA-23 carbapenemase, Nigeria Acinetobacter baumannii is a nonfermentative Gram-negative bacterium commonly found in water and soil. 1 Over the last decade it has become a serious emerging community and nosocomial pathogen worldwide, known to be responsible for life-threatening infections. 2 Carbapenems are the most commonly used antibiotics for treating infections caused by A. baumannii, but an increase in carbapenem-resistant strains of A. baumannii has been reported worldwide over the last decade, 3 mainly through the production of metallo-beta-lactamases (MBLs) or oxacillinases (carbapenemhydrolyzing class D beta-lactamases (CHDLs)). 4 Four major

The study investigated the incidence of Listeria monocytogenes in ready‐to‐eat (RTE) vegetables: (Cucumber, Cucumis sativas; Cabbage, Brassica olerecea; Carrot, Daucus carota; Tomato, Solanum lycopersicum; Lettuce, Lactuca sativa) in six states in South‐Western Nigeria. A total of 555 composite samples were collected from 30 traditional markets within the states and only 244 L. monocytogenes species were isolated by standard methods. The incidence of L. monocytogenes was low and not statistically significant per vegetable type. The percentage distribution of the L. monocytogenes isolates in the RTE vegetables was 28.28, 9.02, 23.36, 19.67, and 19.67 for Cabbage, Carrot, Cucumber, Lettuce, and Tomatoes, respectively. Lagos state had the highest incidence of L. monocytogenes contamination (55%) followed by Ondo (48.89%), Oyo (48.75%), Ogun (44.09%), Osun (34.38%), and Ekiti (33.33%) states, respectively. Although the incidence of L. monocytogenes in the RTE vegetables in South‐Western Nigeria is low, its presence should be a source of concern as it could constitute a public health threat for its consumers.

This study reports a new class of photocatalytic hybrid clay nanocomposites prepared from low-cost sources (kaolinite clay and Carica papaya seeds) doped with Zn and Cu salts via a solvothermal process. X-ray diffraction analysis suggests that Cu-doping and Cu/Zn-doping introduce new phases into the crystalline structure of Kaolinite clay, which is linked to the reduced band gap of kaolinite from typically between 4.9 and 8.2 eV to 2.69 eV for Cu-doped and 1.5 eV for Cu/Zn hybrid clay nanocomposites (Nisar, J.; Århammar, C.; Jamstorp, E.; Ahuja, R. Phys. Rev. B 2011, 84, 075120). In the presence of solar light irradiation, Cu-and Cu/Zn-doped nanocomposites facilitate the electron−hole pair separation. This promotes the generation of singlet oxygen which in turn improves the water disinfection efficiencies of these novel nanocomposite materials. The nanocomposite materials were further characterized using high-resolution scanning electron microscopy, fluorimetry, thermogravimetric analysis, and Raman spectroscopy. The breakthrough times of the nanocomposites for a fixed bed mode of disinfection of water contaminated with 2.32 × 10 7 cfu/mL E. coli ATCC 25922 under solar light irradiation are 25 h for Zn-doped, 30 h for Cu-doped, and 35 h for Cu/Zn-doped nanocomposites. In the presence of multidrug and multimetal resistant strains of E. coli, the breakthrough time decreases significantly. Zn-only doped nanocomposites are not photocatalytically active. In the absence of light, the nanocomposites are still effective in decontaminating water, although less efficient than under solar light irradiation. Electrostatic interaction, metal toxicity, and release of singlet oxygen (only in the Cu-doped and Cu/Zn-doped nanocomposites) are the three disinfection mechanisms by which these nanocomposites disinfect water. A regrowth study indicates the absence of any living E. coli cells in treated water even after 4 days. These data and the long hydraulic times (under gravity) exhibited by these nanocomposites during photodisinfection of water indicate an unusually high potential of these nanocomposites as efficient, affordable, and sustainable point-of-use systems for the disinfection of water in developing countries.

Aim:  Previous analysis of tet39 suggests it may be present in other bacterial species. Hence, we investigated the host range of tet39 among bacterial from a poultry waste polluted river in Southwestern Nigeria. Methods and Results:  Thirteen resistant bacterial isolated from the water and sediment of the polluted river was investigated for the presence of tetracycline resistance genes tetA, tetB, tetC, tet39 and the transposon integrase gene of the Tn916/1545 family by PCR. While tetA, tetB, tetC and integrase genes cannot be detected in any of the organisms, tet39 was detected in eight of the tested organisms including three Gram‐positive species. Sequence analysis showed the genes have high sequence identities (≥99%) with tet39 of Acinetobacter sp. LUH5605, the first and only bacterial genus from which the gene has been reported to date. This is a novel observation. Conclusions:  This study shows that apart from Acinetobacter, tet39 is present in other bacterial species tested in this study. Significance and Impact of the Study:  This study adds to available information on the occurrence and distribution of tet39 among environmental bacteria and suggests that the gene has a broader host range than previously reported.

There are increasing concerns about possible dissemination of clinically relevant antibiotic resistance genes, including genes encoding for carbapenemases in the environment. However, little is known about environmental distribution of antibiotic resistance in Africa. In this study, four polluted urban wetlands in Nigeria were investigated as potential reservoirs of carbapenem-resistant bacteria (CRB). CRB were isolated from the wetlands, characterized by Blue-Carba test, MIC determinations and whole genome sequencing (WGS). Nine of 65 bacterial isolates identified as members of the Pseudomonas putida group (P. plecoglossicida and P. guariconensis, respectively) harboured the metallo-beta-lactamase gene blaVIM-5. WGS revealed the blaVIM-5 in three novel Tn402-like class 1 integron structures containing the cassette arrays aadB|blaVIM-5|blaPSE-1, aadB|blaVIM-5|aadB|blaPSE-1, and blaVIM-5|aadB|tnpA|blaPSE-1|smr2|tnpA, respectively. Strains carrying the aadB|blaVIM-5|blaPSE-1 cassette also carried an identical integron without blaVIM-5. In addition, the strains harboured another Tn402-like class 1 integron carrying bcr2, several multidrug resistance efflux pumps, and at least one of ampC, aph(3”)-lb, aph(6)-ld, tetB, tetC, tetG, floR, and macAB. This is the first report of a carbapenemase gene in bacteria from environmental sources in Nigeria and the first report of blaVIM-5 in environmental bacteria isolates. This result underscores the role of the Nigerian environment as reservoir of bacteria carrying clinically relevant antibiotic resistance genes.