Extended-spectrum ß-lactamase-producing Escherichia coli among humans, chickens and poultry environments in Abuja, Nigeria

BACKGROUND

Globally, chicken is known to be a reservoir for the spread of antimicrobial resistance genes to humans. In Nigeria, antimicrobial drugs are readily accessible for use in poultry production, either for preventive or therapeutic purposes. Extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) are transmissible to humans because of their zoonotic potentials. People working very closely with chickens either on farms or markets are at greater risk. The aim of this study was to investigate the prevalence and zoonotic transmission of ESBL-EC among poultry-workers, chickens, and poultry environments in Abuja, Nigeria.

METHODS

We conducted a cross-sectional study among workers, chickens and poultry environment in selected farms/chicken markets in Abuja. Stool, faecal, and environmental samples were collected from apparently healthy workers, chickens, and farm/market environments from December 2018 to April 2019. Data were collected electronically using an open data kit (ODK) installed on a Smartphone. Antimicrobial resistance was determined using broth micro-dilution methods against a panel of 14 antimicrobial agents. We carried out the phenotypic and genotypic characterization of the isolates. Data were analyzed by computing frequencies, proportions and spearman's correlation (ρ).

RESULTS

Of 429 samples, 26.8% (n = 115) were positive for Escherichia coli (E. coli). Of the 115 E. coli isolates, 32.2% (n = 37) were confirmed ESBL producers by phenotypic characterization. Prevalence of ESBL-EC was highest among both poultry-workers (37.8%; n = 14) and chickens (37.8%; n = 14) followed by the environment (24.3%; n = 9). Both human and chicken isolates showed similar patterns of multidrug resistance to tested antimicrobials with a positive correlation (ρ = 0.91). Among ESBL producers, we observed the dissemination of blaCTX-M (10.8%; n = 4) genes. The coexistence of blaCTX-M-15 and blaTEM-1 genes was observed in 8.1% (n = 3) of the isolates, out of which (66.7%; n = 2) were chicken isolates from the farm, while a single human isolate was from the chicken market.

CONCLUSIONS

ESBL-EC isolates were prevalent amongst apparently healthy individuals, chickens and the poultry farm/market environment in Abuja. It is important to educate healthcare workers that people in proximity with poultry are a high-risk group for faecal carriage of ESBL-EC, hence pose a higher risk to the general population for the spread of antimicrobial resistance.

Prevalence and risk factors for multi-drug resistant Escherichia coli among poultry workers in the Federal Capital Territory, Abuja, Nigeria

Background

Antimicrobial resistance has emerged as a global health threat. Antimicrobial resistant Escherichia coli infections are associated with high morbidity and expenditure when compared with infections caused by susceptible strains. In Nigeria, antimicrobial drugs are readily available over-the-counter with potential for indiscriminate use by poultry farmers and eventual development of drug resistance. The objective of this study was to investigate prevalence and risk factors for multi-drug resistant E. coli among poultry workers (PW) in Abuja, Nigeria.

Materials and methods

A cross-sectional study was conducted among 122 randomly selected apparently healthy poultry workers (poultry-farmers/ sellers) in Municipal and Kuje Area Councils from December 2018 to April 2019. Data was collected on socio-demographics and exposure factors using a structured interviewer-administered questionnaire. E. coli was isolated and identified from stool samples of poultry workers. Antibiotic susceptibility testing was done using Kirby-Bauer disk diffusion method. Multidrug resistance (MDR) was defined as resistance to three or more classes of antimicrobials. Data was analyzed by computing proportions, prevalence odds-ratios (POR) and logistic regression at 5% significance level.

Results

Among PW, there were 121 males (99.2%). Mean age of the male workers was 30.6 ± 9.7years, 54.6% (n = 66) married, 57.9% (n = 70) had secondary education and 62.0% (n = 75) were farm-workers. Prevalence of E. coli was 39.7% (n = 48), highest among farm-workers (POR = 2.7, 95% Confidence Interval [CI] = 1.3–5.7; p = 0.01) compared to poultry-sellers. Of the 48 E. coli isolates, 16.7% (n = 8) were extended spectrum beta lactamase (ESBL) producers and 79.2% (n = 38) were MDR. We detected resistance against Tetracycline: (83.3%, n = 40), Sulfamethoxazole-Trimethoprim: (79.2%, n = 38), Ampicillin: (77.1%, n = 37), Streptomycin: (72.9%, n = 35), Nalidixic acid: (50%, n = 24), Gentamicin: (41.7%, n = 20), Chloramphenicol: (31.3%, n = 15), Cephalothin: (27.1%, n = 13), Nitrofurantoin: (10.4%, n = 5) and Imipenem: (6.3%, n = 3). Absence of lavatory (POR = 2.7, 95% CI = 1.1–6.7); existence of farm/market for >10years (POR = 2.5, 95% CI = 1.1–5.4) and PW’s history of diarrhea in last three months (POR = 2.8, CI = 1.2–6.3) were associated with MDR. Controlling for age, absence of lavatory (adjusted OR [aOR] = 4.31, 95% CI = 1.6–11.9); PW’s history of diarrhea in last three months (aOR = 3.3,95%CI = 1.3–8.5) and work exposure >10years (aOR = 0.3, 95%CI = 0.1–0.9) remained independent risk factors for MDR.

Conclusion

Prevalence of resistant E. coli was highest among farm-workers and associated with older farms/markets, occupational exposure of over 10 years and poor hygienic measures. The management of Municipal and Kuje Area Councils were recommended to provide lavatories for public use in farm-settlements/markets. The importance of hand-hygiene and responsible use of antimicrobials in poultry production was emphasized.

Salmonella serovars and their distribution in Nigerian commercial chicken layer farms

Commercial poultry farms (n° 523), located in all the six regions of Nigeria were sampled with a view to generate baseline information about the distribution of Salmonella serovars in this country. Five different matrices (litter, dust, faeces, feed and water) were collected from each visited farm. Salmonella was isolated from at least one of the five matrices in 228 farms, with a farm prevalence of 43.6% (CI95[39.7-48.3%]). Altogether, 370 of 2615 samples collected (14.1%, CI95[12.8; 15.5%]) contained Salmonella. Considering the number of positive farms and the number of positive samples, it was evident that for the majority of the sampled farms, few samples were positive for Salmonella. With regard to the matrices, there was no difference in Salmonella prevalence among the five matrices considered. Of the 370 isolates serotyped, eighty-two different serotypes were identified and Salmonella Kentucky was identified as having the highest isolation rate in all the matrices sampled (16.2%), followed by S. Poona and S. Elisabethville. S. Kentucky was distributed across the country, whereas the other less frequent serovars had a more circumscribed diffusion. This is one of few comprehensive studies on the occurrence and distribution of Salmonella in commercial chicken layer farms from all the six regions of Nigeria. The relatively high prevalence rate documented in this study may be attributed to the generally poor infrastructure and low biosecurity measures in controlling stray animals, rodents and humans. Data collected could be valuable for instituting effective intervention strategies for Salmonella control in Nigeria and also in other developing countries with a similar poultry industry structure, with the final aim of reducing Salmonella spread in animals and ultimately in humans.

Performance of an HRP-2 rapid diagnostic test in Nigerian children less than 5 years of age

The diagnostic performance of histidine-rich protein 2 (HRP-2)-based malaria rapid diagnostic test (RDT) was evaluated in a mesoendemic area for malaria, Kaduna, Nigeria. We compared RDT results with expert microscopy results of blood samples from 295 febrile children under 5 years. Overall, 11.9% (35/295) tested positive with RDT compared with 10.5% (31/295) by microscopy: sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100%, 98.5%, 88.6%, and 100%, respectively. The RDT sensitivity was not affected by transmission season, parasite density, and age. Specificity and positive PV decreased slightly during the high-transmission season (97.5% and 83.3%). The RDT test positivity rates in the low- and high-transmission seasons were 9.4% and 13.5%, respectively. Overall, the test performance of this RDT was satisfactory. The findings of a low proportion of RDT false positives, no invalid and no false-negative results should validate the performance of RDTs in this context.

Human brucellosis: seroprevalence and associated exposure factors among abattoir workers in Abuja, Nigeria - 2011

INTRODUCTION

Brucellosis, a neglected debilitating zoonosis, is a recognized occupational hazard with a high prevalence in developing countries. Transmission to humans can occur through contact with infected animals or animal products. Brucellosis presents with fever. In Nigeria, there is a possibility of missed diagnoses by physicians leading to a long debilitating illness. We conducted a study to determine the seroprevalence and factors associated with Human Brucellosis (HB) among abattoir-workers in Abuja, Nigeria.

METHODS

We conducted a cross-sectional study and selected abattoir-workers using stratified random sampling. Structured questionnaires were used to collect data on demographics and exposure-factors. We tested the workers' serum-samples using Rose-Bengal (RBPT) and ELISA tests. A worker with HB was one whose serum tested positive to RBPT or ELISA. We tested differences in proportions between workers with HB and those without HB using odds-ratio and X(2) tests.

RESULTS

Of 224 workers, 172 (76.8%) were male and mean age was 30 + 9.0 years. Of 224 sera collected, 54 were positive giving a seroprevalence of 24.1%. Of these, 32 (59.3%) were butchers, and 11 (20.4%) were meat-sellers. Slaughtering animals while having open-wounds (Odds-ratio (OR) = 2.15, 95% Confidence Interval (CI) = 1.15-4.04); occupational-exposure of >5years (OR = 2.30, CI = 1.11-4.78) and eating raw meat (OR = 2.75, CI = 1.21-6.26) were significantly associated with HB. Multivariate analyses showed that occupational-exposure of >5years (Adjusted OR (AOR) =2.45, CI = 1.15 - 5.30) and eating raw-meat (AOR = 2.64, CI = 1.14 - 6.14) remained significantly associated with HB.

CONCLUSION

Seroprevalence of HB among abattoir-workers in Abuja was high. Factors associated with HB were occupational-exposure of >5years and eating raw-meat. Abattoir-workers should be discouraged from eating raw-meat and educated on adherence to safe animal-product handling practices.

Plasmids and outer membrane proteins of Yersinia enterocolitica and related species of swine origin

Yersinia enterocolitica and other pathogenic yersiniae harbor a plasmid termed pYV which is required for the full expression of virulence. The pYV codes for the release of a set of proteins called Yops and two outer membrane proteins Yad A and Ylp A. In the present study, 80 strains of Y. enterocolitica and related species were examined for the possession of the pYV and the ability to express Yops and Yad A. Only Y. enterocolitica belonging to serogroups O:1,2,3, O:3, O:5,27, O:8, and O:9 harbored the virulence plasmid and were positive for the presence of the ancillary proteins. The restriction fragment patterns of the pathogenic bioserotypes belonging to the same serogroup affiliation were similar irrespective of whether they were of swine origin, reference strains, or human clinical isolates. The same was also true of the electrophoretic patterns of the Yops. Our findings are in agreement with previous studies and support the view that pigs may be an important reservoir of pathogenic Y. enterocolitica.

Isolation of Yersinia enterocolitica (0:5,27 biotype 2) from a common garter snake

Yersinia enterocolitica serotype 0:5,27 biotype 2 was isolated from the intestinal contents of a common garter snake (Thamnophis sirtalis). The isolate possessed virulence associated phenotypes in all tests conducted. It was susceptible to amikacin, ampicillin/sulbactam, aztreonam, cefoperazone, cefotaxime, ceftazidime, ceftriaxone, cefuroxime, ciprofloxacin, gentamicin, imipenem, mezlocillin, norfloxacin, piperacillin, ticarcillin/clavulanic acid, trimethoprim-sulfamethoxazole, tobramycin, chloramphenicol and tetracycline. The isolate harbored the virulence plasmid.

Detection of pathogenic Yersinia enterocolitica by polymerase chain reaction and digoxigenin-labeled polynucleotide probes

Yersinia enterocolitica is widespread in nature, but only a few bioserotypes are involved in human infections. Pigs are considered to be the major reservoirs of pathogenic strains. It is essential to have an accurate and rapid method for the detection of pathogenic yersiniae. To achieve this objective, 19-base synthetic oligonucleotide primers were used in a polymerase chain reaction (PCR) to detect the ail gene (which is conserved only in pathogenic strains) in strains of Y. enterocolitica and related species originating from pigs or pork products. Digoxigenin-labeled probes derived from the ail, inv, and yst genes were also evaluated on these strains. The PCR amplified a 273-bp fragment of the ail gene involved in eukaryotic cell invasion and serum resistance. The PCR detected template DNA only in strains of Y. enterocolitica traditionally classified as human pathogens but not in biotype 1A strains and related species. Other members of the family Enterobacteriaceae were also negative for the target gene. The digoxigenin-labeled ail probe gave identical results to the PCR. By use of this nonisotopic method, inv-homologous DNA was detected only among yersiniae, except for Y. ruckeri. Although all pathogenic serotypes of Y. enterocolitica were positive for the heat-stable enterotoxin yst gene, two strains of biotype 1A, one Y. intermedia strain, and six other species of the Enterobacteriaceae were also positive. Our results support the notion that pigs constitute an important reservoir of pathogenic Y. enterocolitica and that the inv-homologous sequence is Yersinia specific.

Comparison of Two Enrichment Protocols for the Detection of Yersinia in Slaughtered Pigs and Pork Products

Two enrichment methods were evaluated in the course of a study to determine the occurrence of Yersinia enterocolitica in slaughtered pigs and pork products. Eighty Yersinia strains belonging to one of four species were recovered. Of the 67 strains of Y. enterocolitica encountered, 48 belonged to known pathogenic bioserotypes. The enrichment medium incorporating irgasan, ticarcillin, and potassium chlorate (ITC) was found to be superior to the two-step enrichment method (YER/BOS) for isolation of pathogenic Y. enterocolitica from throat swabs. When pork products were examined using the two methods, YER/BOS was by far superior for recovery of yersiniae, although all strains isolated by this method belonged to nonpathogenic bioserotypes and Y. enterocolitica -like organisms. Conversely, ITC enrichment recovered fewer strains but most were pathogenic bioserotypes. Thus, swine can serve as a reservoir of virulent Y. enterocolitica in Saskatchewan, and ITC enrichment is recommended for the isolation of these strains.

In vitro antimicrobial susceptibilities of Yersinia enterocolitica and related species isolated from slaughtered pigs and pork products

The MICs for and disk susceptibilities of 80 strains of yersiniae isolated from swine and pork products were determined. The most effective antimicrobial agents in the in vitro tests were the aminoglycosides, cephalosporins (cefotaxime, ceftazidime, and ceftriaxone), imipenem, ticarcillin-clavulanic acid, aztreonam, ciprofloxacin, norfloxacin, and trimethoprim-sulfamethoxazole. There was a high percentage of resistance among the strains to penicillinase-sensitive penicillins, erythromycin, clindamycin, vancomycin, cefazolin, and cephalothin.