Occurrence and antibiogram signatures of some Vibrio species recovered from selected rivers in South West Nigeria.

Vibrio species, widely distributed in water environments, has emerged as a prominent cause of water and food-related disease outbreaks posing significant risk to human and animal health worldwide. About 40% of presumptive isolates recovered from four selected rivers in Southwest Nigeria and, established as Vibrio species genus through polymerase chain reaction techniques., were subjected to antibiotic susceptibility testing against a panel of 18 commonly used antibiotics. The relative prevalence of key Vibrio species (V. parahaemolyticus, V. vulnificus, V. mimicus, V. harveyi, and V. cholerae) was in the order 17%, 13.3%, 4.4%, 2.2%, and 2.2% respectively. Antibiotic resistance by all Vibrio species was mostly observed against doxycycline (71-89%), erythromycin (86-100%), tetracycline (71-89%), rifampicin (86-100%), and sulfamethoxazole (87-100%), though susceptibility to meropenem (86-100%), cephalothin (60-100%), norfloxacin (93-100%), ciprofloxacin (88-100%), amikacin (64-100%), gentamicin (57-74%), and trimethoprim/sulfamethoxazole (57-81%) was equally observed in all species. Vibrio mimicus expressed highest resistance against streptomycin and chloramphenicol (64%), while V. vulnificus (52%) and V. cholerae (57%) had the highest resistance against cephalothin. High resistance against ampicillin (57%) and amoxicillin (50%) was exhibited by V. cholerae and V. mimicus respectively. Indexes of multiple antibiotic resistances (MARI) among Vibrio species ranged between 0.11 and 0.72 with the highest MAR index of 0.72 observed in one isolate of V. vulnificus. This study reveals high prevalence of Vibrio species in the selected rivers as well as elevated resistance against some first-line antibiotics, which suggests possible inappropriate antimicrobial usage around study communities. We conclude that the freshwater resources investigated are unfit for domestic, industrial, and recreational uses without treatment prior to use and are potential reservoirs of antibiotic-resistant Vibrio species in this environment.

Incidence and antimicrobial susceptibility fingerprints of Plesiomonas shigelliodes isolates in water samples collected from some freshwater resources in Southwest Nigeria.

Plesiomonas shigelloides, is an emerging and significant enteric pathogen in water having implication in both localised and gastrointestinal infections with characteristic of displaying high resistance against commonly used antibiotics. This study evaluated the prevalence of Plesiomonas shigelloides and their antibiogram fingerprints in water sample collected from four rivers in South-western Nigeria. In all, 148 presumptive Plesiomonas shigelloides isolates was recovered from the rivers out of which 66 (44.6%) were confirmed positive for the organism using polymerase chain reaction techniques. Confirmed isolates were evaluated for their antibiogram profiles against a panel of 20 antimicrobials using the disc diffusion method and further screened for relevant antibiotic resistance genes. Resistance of the isolates against the antimicrobials followed the order: sulphamethoxazole (100%), erythromycin (93%), ampicillin (90%), cephalotin (82%), streptomycin (64%), and chloramphenicol (58%), amoxicillin (53%), cefotaxime (50%), tetracycline (49%), neomycin (38%) and trimethoprim + sulphamethoxazole (38%). Conversely, all the isolates were susceptible against netilmicin, and susceptibility against the other antibiotics follows the order: meropenem (94%), gentamicin (88%), imipenem (79%), amikacin (70%), ciprofloxacin (70%), norfloxacin (59%), trimethoprim (56%) and ceftazidine (56%). The multiple antibiotic resistance indices of the organism were higher than the accepted threshold of 0.2. The incidence of 11 antimicrobial resistance determinants were obtained as follows: [sulphonamides; (sulI (18%), sulII (20%), dfr1 (70%), dfr(18) (5%)), [beta-lactams; (ampC 37%)], [tetracyclines; (tetA (78%), tetE (57%)], [phenicols; (catII (16%), cmlA1 (11%)] and [aminoglycosides; (aphA2 (36%) and strA (67%)]. Pearson chi-square exact test revealed positive associations among tetA, tetE, sullI and catII and tetA genes. To the best of our knowledge, this is the first report on the incidence and antibiogram fingerprint of P. shigelloides in these freshwater resources and we conclude that these rivers are important reservoirs of multiple antimicrobial resistant biotypes of this organism, and consequently a threat to public health.

Concentrations of Polybrominated Diphenyl Ethers (PBDEs) in Water from Asunle Stream, Ile-Ife, Nigeria.

This study assessed the concentrations of polybrominated diphenylethers (PBDEs) in stream water obtained from Asunle stream, an adjoining stream of the Obafemi Awolowo University dumpsite. Water samples were collected for a period of eight months from six different locations comprising of a spot upstream in an uphill area relative to the refuse dumpsite and five others downstream along the stream course. The sampled waters were extracted with dicholoromethane using liquid-liquid extraction method and cleanup was carried out with silica gel. The final extracts after concentration were analyzed using GC-MS/MS. The recovery experiments were adequate (105%-110%). The mean levels of Æ©6PBDEs compounds analyzed ranged from 0.03 to 0.45 ng/mL. Seasonal variability of PBDEs indicated that higher levels were found during the wet season. The levels of PBDEs recorded in this work were relatively lower compared to the values reported in the literature from other developed nations.

Assessment of polybrominated diphenyl ethers in sediment of Asunle stream of the Obafemi Awolowo University, Ile-Ife, Nigeria.

Assessment of levels of polybrominated diphenyl ethers (PBDEs) from the sediment of Asunle stream, an adjourning stream of the Obafemi Awolowo University dumpsite, has been carried out. Sediment samples were collected from the stream at six locations for a period of 8 months, composed of 4 months each of wet (May-Aug) and dry (Nov-Feb) seasons. Soxhlet extraction was employed for the isolation of all the target compounds from the sediment samples. Extracts were further subjected to multi-layer column chromatography employing different forms of silica gel. The prepared samples were analyzed using GC-MS. The overall mean concentrations of the total PBDEs ranged from 1.80 to 9.46 ng/g. The results showed that the concentrations of the PBDEs were slightly higher during the wet season than those during the dry season. In all the studied locations, BDE28, BDE47, BDE99, BDE100, BDE153, and BDE154 were detected in all the sediment samples at concentrations that ranged from 0.73 to 10.43 ng/g. Results of this study indicated that BDE153 was the major pollutant of the Asunle stream sediments.

Speciation study of the heavy metals in commercially available recharge cards coatings in Nigeria and the health implication.

This work assessed levels of heavy metals exposure from silver coatings of mobile phones recharge cards of three major companies (designated as A, B and C) with price denominations 100, 200 and 400 from companies A, B and C respectively, which were carefully scratched using a plastic scraper into a glass tube. The coatings were acid digested for total metal concentration, while speciation experiment for Mn, Cu, Cd and Pb was carried out. Total metals and speciation analysis were done using AAS and XRF techniques. The total metal concentration from XRF analysis was in the range: Ca (70-2140 µg/g), K (20-4930 µg/g), Sc (80-270 µg/g), Ti (1530-12,580 µg/g), Fe (50-6660 µg/g), Ni (20-2040 µg/g), Cu (20-850 µg/g) and Zn (40-460 µg/g). Cr had the lowest concentration (10 µg/g) in A ( 400) while Ti had the highest concentration (12,580 µg/g) in C ( 500) for all the coatings analyzed. AAS and XRF results agreed closely except for Fe with higher concentration. A ( 100) contained high concentration of the metals compared with others. Speciation study identified Mn as the most mobile element when present in the environment.

Determination of organochlorine pesticides in the agricultural soil of Oke-Osun farm settlement, Osogbo, Nigeria.

This study was conducted to evaluate the levels and seasonal variations of some organochlorine pesticides (OCPs) in the cultivated land of Oke-Osun farm settlement, Osogbo, Nigeria. A field sampling programme was conducted in the rainy and dry seasons for 4 months each resulting in the analysis of a total of 40 samples. Soil samples collected at 20-m intervals were air-dried to a constant weight, sieved through a mesh of 2.0-mm pore size and selected by coning and quartering method. Solid-liquid extraction was used to extract OCPs from the soil. Qualitative identifications and quantitative evaluation of the OCPs were carried out with the aid of a Perkin Elmer gas chromatograph coupled with electron capture detector. Seasonal mean ranges of OCPs in soil (µg/kg) were 13.09 ± 21.66 ß-BHC-42.01 ± 17.50 p, p(')-DDT in rainy season and 30.74 ± 17.38 α-BHC-82.88 ± 32.24 p, p(')-DDT in the dry season. The results obtained from this study revealed that agricultural soil samples of Oke-Osun farm settlement were contaminated with persistent organochlorine pesticides mainly as a result of their applications by farmers. Higher levels of OCPs were obtained for dry season than the rainy season. There were indications from this study that pesticides that have deleterious health effects on humans previously placed under legal restrictions by regulatory agencies were still being used by the farmers of Oke-Osun farm settlement and this gives cause for environmental concern.