Incidence of antibiotic resistance genotypes of Vibrio species recovered from selected freshwaters in Southwest Nigeria.

Vibrio species are classified as potent hazards because of their tendency to effect serious diseases like cholera and other gastrointestinal ailments in humans, as well as vibriosis in fish. A total of 144 freshwater samples were aseptically collected monthly across four rivers (Asejire, Ona, Dandaru and Erinle rivers) over a 12-month period from which Vibrio spp. were isolated using culture procedures, confirmed by means of biochemical test as well as Polymerase Chain Reaction (PCR) assay and further characterized for their phenotypic antibiotic susceptibilities and relevant antimicrobial resistant determinants by PCR. Three hundred and fifteen (58%) isolates confirmed across the sampled sites (Asejire = 75, Dandaru = 87, Eleyele = 72, Erinle = 81) showed high resistance against erythromycin-95%, Sulphamethoxazole-94%, rifampicin-92%, doxycycline-82%, tetracycline-75%, amoxicillin-45%, cephalothin-43% and varied susceptibilities to other antibiotics. The multiple antibiotic resistance indices of 97% of the Vibrio isolates were above the 0.2 threshold limit with MAR phenotype pattern E-SUL-RF-TET-DOX (0.38) found to be the most prevalent pattern among the isolates. The distributions of resistance determinant of the tested antibiotics were revealed as follows: sulII 33%, sulI 19% (sulfonamides); blaOXA 27%, ampC 39%, blapse 11% (beta-lactams); tetA 28%, tetE 20%, tet39 8%, (tetracyclines) and strA 39%. aacC2 24%, aphA1 14% (aminoglycosides). Strong positive associations were observed among tetA, sulI, tetE and sulII. This study raises concerns as these selected rivers may contribute to the environmental spread of waterborne diseases and antibiotic resistance genes. Therefore, we recommend environmental context-tailored strategies for monitoring and surveillance of resistance genes so as to safeguard the environment from becoming reservoirs of virulent and infectious Vibrio species.

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.