Invasive nontyphoidal salmonellosis (NTS) caused by multidrug resistant (MDR)
This study is the first to report on resistance levels and profiles of
The study was conducted in five districts in the Ashanti Region, Ghana. These districts were suggested by the Ashanti regional Veterinary Department due to their higher density of pig farms and well established pig farmers’ associations. The farms were situated in five districts within the Ashanti Region of Ghana: Ejisu-Juaben District (12 settlements), Atwima Nwabiagya District (12 settlements), Bosomtwe and Atwima Kwanwoma Districts (5 towns), and Kwabre East District (10 towns). Ashanti Region was chosen due to proximity to the university and the relatively larger and commercialised number of pig farms.
The farms visited were those enlisted by the pig farmers’ associations in the various districts. Farms were carefully chosen from villages and towns within the districts to ensure a fair representation. Farms in which the owners were absent or unwilling to undertake the study were not included. Farms that were within proximity of 100 meters were not selected.
A total of 108 farms were obtained from the various settlements within the five districts: Ejisu Juaben (43 farms), Atwima Nwabiagya (20 farms), Bosomtwe-Atwima-Kwanwoma (24 farms), and Kwabre East (21 farms).
Briefly, between May and July 2012, fresh faeces were collected from ten pigs in each of the 108 pig farms. These faeces were mixed up and placed into a sample tube, making 108 multiply composite faecal samples. Samples were transported to the laboratory in sample tubes on ice. Ten grams of each sample was suspended in 100 mL of 0.9% saline with 20% glycerol, diluted to 10−1, and immediately stored at −20°C till analysis.
Stored samples were thawed, diluted to 10−2, and precultured in enriched soy peptone broth (Oxoid, Basingstoke, UK). Selenite broth (Thermo Fischer, UK), modified brilliant green agar (Thermo Fischer, UK), and the Kaufman-White typing method (scheme) were used to, respectively, select, detect, and isolate and confirm the presence of
A simple questionnaire asking farmers for the antibiotics used within the last six months was also administered to guide the choice of antibiotics for sensitivity testing.
Antibiotic sensitivity testing discs (amoxicillin-10
The zones of inhibition produced by the antibiotics were measured thrice and the average was compared with the CLSI breakpoints [
The number and percentages of resistant isolates were analysed with Microsoft Excel© 2010 (Microsoft Corporation, Microsoft Office package, 2010, USA).
Ethical exemption and study approval were obtained from the Faculty of Pharmacy of the Kwame Nkrumah University of Science and Technology. The approval of the regional and district veterinary offices and the farmers were obtained before faecal collection began and, where possible, verbal consent was obtained using accepted methods [
Each of the 108 multiply composite faecal samples comprised faeces from 10 animals per farm. From the 108 farms studied, 72 samples were positive for
Summary of
Antibiotics | Number of resistant isolates ( |
Percentage (%) |
---|---|---|
Amoxicillin | 27 | 71.1 |
Ciprofloxacin | 8 | 21.1 |
Norfloxacin | 3 | 7.9 |
Gentamicin | 0 | 0 |
Streptomycin | 27 | 71.1 |
Tetracycline | 17 | 44.7 |
Doxycycline | 15 | 39.5 |
Sulphamethoxazole-trimethoprim | 3 | 7.9 |
Antibiotic spectrum of multidrug resistant
Antibiotics | Number of multidrug resistant isolates ( |
Percentage of multidrug resistant isolates (%) |
---|---|---|
Amoxicillin and streptomycin | 23 | 79.3 |
Amoxicillin, streptomycin, and ciprofloxacin | 7 | 24.1 |
Amoxicillin, streptomycin, ciprofloxacin, tetracycline, and doxycycline | 6 | 20.7 |
Amoxicillin, streptomycin, tetracycline, and doxycycline | 12 | 41.4 |
Amoxicillin, streptomycin, tetracycline, doxycycline, and sulphamethoxazole-trimethoprim | 2 | 6.9 |
Amoxicillin, streptomycin, ciprofloxacin, tetracycline, doxycycline, and sulphamethoxazole-trimethoprim | 1 | 3.4 |
Ciprofloxacin, tetracycline, and doxycycline | 6 | 20.7 |
The study resulted in an isolation rate of 72
In a study by Ojo and colleagues [
Further studies would be needed to determine the resistance mechanisms in the resistant isolates and determine the type of
There is a substantial presence of multidrug resistant
The authors declare that they have no competing interests and the sponsors had no role or whatsoever in the preparation of the paper, data collection, and analysis and decision to publish.
This research was partially funded by the ADMER project (STATENS SERUM INSTITUT, Denmark). The author thanks the farmers and the executives of the pig farmers’ associations in all the districts visited for their cooperation and participation, the veterinarians of the districts visited, and the regional veterinarian for their inputs towards this research, Professor D. B. Okai for his assistance with questionnaires and information on pig science, Dr. Benard Keraita, Mr. Francis Adu, and Mrs. Vivian Etsiapa Boamah for their technical and literary assistance. The authors also thank the anonymous reviewers for their helpful comments.