Isolation and characterisation of colistin-resistant Enterobacterales from chickens in Southeast Nigeria.

OBJECTIVES: Resistance to colistin (CST) mediated by mobile genetic elements has had a broad impact worldwide. There is an intensified call for epidemiological surveillance of mcr in different reservoirs to preserve CST for future generations. In Nigeria, the poultry industry is a key livestock sector. This study was undertaken to screen putative colistin-resistant Enterobacterales (CST-r-E) from poultry birds in Southeast Nigeria and to determine the genetic relatedness of mcr-harbouring isolates. METHODS: Faecal and cloacal swab samples (n = 785) were collected from chickens in 17 farms located in three contiguous states in Southeast Nigeria between March-November 2018. Following selective culture, CST-r-E were isolated. Confirmation of CST resistance, antimicrobial susceptibility testing, molecular detection of genes mcr-1 to mcr-10, multilocus sequence typing (MLST) and randomly amplified polymorphic DNA (RAPD) analysis were performed on the isolates. A questionnaire was distributed to investigate the knowledge about CST and its use of chicken farm caretakers. RESULTS: Of the 785 samples evaluated, 45 (5.7%) were positive for 48 CST-r-E, among which 23 harboured the mcr-1 gene (22 Escherichia coli and 1 Klebsiella pneumoniae). In two E.coli isolates, a new allelic variant (mcr-1.22) was detected. RAPD analysis allowed the identification of 11 different fingerprints. MLST also revealed 11 STs, with 3 of them being novel. CONCLUSION: mcr has significantly spread in poultry birds of Southeast Nigeria, which poses a worrisome risk to veterinary and human health. Strategies to prevent indiscriminate use of CST in farms should be quickly adopted before CST resistance becomes a huge global health issue.

Parasitological and histopathological effects of immunosuppression in guinea-pigs (Cavia porcellus) experimentally infected with Schistosoma haematobium.

The parasitological and histopathological effects of immunosuppression in guinea-pigs (Cavia porcellus) experimentally infected with Schistosoma haematobium were studied. A total of 16 guinea-pigs were divided into four groups (four per group): non-immunosuppressed, non-infected group (NN); immunosuppressed, non-infected group (IN); immunosuppressed, infected group (II); non-immunosuppressed, infected group (NI). The IN and II groups were immunosuppressed with 5 mg/kg prednisolone while the II and NI animals were infected with 200-300 S. haematobium cercariae. Excretion of eggs in urine/faeces, worm burden and histopathology of some vital organs of the guinea-pigs were studied. Eggs of S. haematobium were observed in the urine of the NI and II groups from 9 weeks post-infection and in faeces from 10 and 13 weeks post-infection for the NI and II groups, respectively. However, II animals excreted more viable eggs in urine and faeces than those of the NI group. Worm recovery at 14 weeks post-infection showed that NI and II guinea-pigs had more female worms than male worms and a greater proportion of worm recovery for NI animals was of immature worms. Significant differences (P < 0.05) existed between female, male and immature worm burden of the two groups but not in their total worm burden (P>0.05). Histological changes, which were notably reactions to adult S. haematobium worms, were observed in the organs of the NI and II groups but these changes were seen more in the organs of the immunosuppressed, infected (II) than in the non-immunosuppressed, infected (NI) guinea-pigs. The results suggest that immunosuppression before infection increased worm survival and had a moderate effect on liver and bladder histology of S. haematobium infected guinea-pigs.

Effect of iodine supplementation on thyroid and testicular morphology and function in euthyroid rats.

Seventy-five male weaner euthyroid rats, randomly divided into three equal groups were used to evaluate the effect of iodine supplementation in the diet on growth and spermatogenesis. From the age of six weeks, the rat groups were fed normal diet containing 0.05 mg iodine/Kg diet (A); normal diet supplemented with 0.5 mg/Kg iodine (B) and normal diet supplemented with 3.0 mg/Kg iodine for a period of 90 days. Thereafter, all three groups were fed the normal diet for another 60 days. Body weight and feed consumption were determined; morphomeric studies of thyroid glands, testes and epididymes were carried out. Spermatogenesis was evaluated with epididymal (ESC) and testicular sperm counts (TSC). Increasing iodine intake significantly (p < 0.05) decreased mean body weight from day 30 of supplementation. Iodine supplementation influenced feed conversion ratio and efficiency in feed utilization in an inconsistent pattern. Supplementation did not significantly (p > 0.05) alter the size of thyroid glands, but increased the mean weights of the testes and epididymes to levels significantly (p < 0.05) higher than values for non-supplemented rats at specific stages of the study, especially at the highest (3 ppm) level of iodine supplementation. However, supplementation resulted generally in lower sperm counts, which was significant (p < 0.05) in the case of the epididymes. The results of the study show that iodine supplementation to weaner, non-iodine deficient euthyroid rats at 3ppm not only retard weight gain but could also reduce fertility by lowering epididymal sperm counts.