Browsing by Author "Medardus, J. J."

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Bovine tuberculosis and brucellosis in livestock at the Greater Ruaha Ecosystem
(The Tropical Veterinarian) Medardus, J. J.
Bovine tuberculosis and brucellosis in livestock at the Greater Ruaha Ecosystem
(The Tropical Veterinarian, 2020) Medardus, J. J.
A cross-sectional study was conducted to determine the prevalence of bovine tuberculosis (BTB) and the seroprevalence of brucellosis in livestock at the Greater Ruaha Ecosystem in Tanzania. The study further characterized the Mycobacterium spp. from the slaughtered livestock. Survey conducted to assess potential herd-level risk factors for BTB and brucellosis revealed that the respondents’ ethnicity and herd mixing were the significant risk factors. Twenty-eight percent of 102 cattle herds had at least one positive or suspect BTB reactor. The overall prevalence of BTB infection in the cattle was 1.32% (18/1368). Forty-two percent of 93 flocks of the small ruminants had at least one brucellosis seropositive animal. The overall seroprevalence of brucellosis in the cattle and small ruminants was 6.6%. Although the prevalence of both diseases was relatively low for individual animals, herd-level prevalence was high, suggesting that infection is widespread in the study area and a significant number of households are at risk. Mycobacterium bovis strain identified via polymerase chain reaction (PCR) was confirmed by spoligotyping as spoligotype SB0133. This cattle strain of M. bovis was similar to previously reported involving wild animals in adjacent protected areas. Isolation of identical M. bovis from the wildlife and livestock and the demonstration of Brucella spp. seroprevalence in livestock in the same interface, strongly suggest livestock-wildlife interspecies sharing of these pathogens. Occurrence of the microorganisms poses a serious challenge to disease management strategies in pastoralist communities in the interface area.
Citrobacter as a gastrointestinal pathogen, its prevalence and molecular characterization of antimicrobial resistant isolates in food-producing animals in Morogoro, Tanzania
(TANZANIA VETERINARY ASSOCIATION) Medardus, J. J.
In-feed use of heavy metal micronutrients in U.S. Swine production systems and its role in persistence of multidrug-resistant Salmonellae
(ASM News- American Society for Microbiology) Medardus, J. J.; Molla, B. Z.; Nicol, M.; Morrow, W. M.; Rajala-Schultz, P. J.; Kazwala, R.; Gebreyes, W. A.
In-feed use of heavy metal micronutrients in U.S. Swine production systems and its role in persistence of multidrug-resistant Salmonellae
(ASM News- American Society for Microbiology, 2014) Medardus, J. J.; Molla, B. Z.; Nicol, M.; Morrow, W. M.; Rajala-Schultz, P. J.; Kazwala, R.; Gebreyes, W. A.
The study aimed to characterize the role of heavy metal micronutrients in swine feed in emergence of heavy-metal-tolerant and multidrug-resistant Salmonella organisms. We conducted a longitudinal study in 36 swine barns over a 2-year period. The feed and fecal levels of Cu2+ and Zn2+ were measured. Salmonella was isolated at early and late finishing. MICs of copper sulfate and zinc chloride were measured using agar dilution. Antimicrobial susceptibility was tested using the Kirby-Bauer method, and 283 isolates were serotyped. We amplified pcoA and czcD genes that encode Cu2+ and Zn2+ tolerance, respectively. Of the 283 isolates, 113 (48%) showed Cu2+ tolerance at 24 mM and 164 (58%) showed Zn2+ tolerance at 8 mM. In multivariate analysis, serotype and source of isolates were significantly associated with Cu2+ tolerance (P < 0.001). Fecal isolates were more likely to be Cu2+ tolerant than those of feed origin (odds ratio [OR], 27.0; 95% confidence interval [CI], 2.8 to 250; P = 0.0042) or environmental origin (OR, 5.8), implying the significance of gastrointestinal selective pressure. Salmonella enterica serotypes Typhimurium and Heidelberg, highly significant for public health, had higher odds of having >20 mM MICs of Cu2+ than did “other” serotypes. More than 60% of Salmonella isolates with resistance type (R-type) AmStTeKm (32 of 53) carried pcoA; only 5% with R-type AmClStSuTe carried this gene. czcD gene carriage was significantly associated with a higher Zn2+ MIC (P < 0.05). The odds of having a high Zn2+ MIC (≥8 mM) were 14.66 times higher in isolates with R-type AmClStSuTe than in those with R-type AmStTeKm (P < 0.05). The findings demonstrate strong association between heavy metal tolerance and antimicrobial resistance, particularly among Salmonella serotypes important in public health.
Investing in food safety for developing countries: opportunities and challenges in applying whole-genome sequencing for food safety management
(Food and Agriculture Organization of the United Nations / Mary Ann Liebert, Inc.) Apruzzese, I.; Song, E.; Bonah, E.; Sanidad, V. S.; Leekitcharoenphon, P.; Medardus, J. J.; Abdalla, N.; Hosseini, H.; Takeuchi, M.
Molecular characterization of multidrug resistant salmonella isolates from food animals and animal products in Tanzania
(Tanzania Veterinary Journal) Medardus, J. J.; Gebreyes, W. A.
Phenotypic and genotypic characterization of salmonella enterica in captive wildlife and exotic animal species in Ohio, USA
(Blackwell Verlag GmbH) Farias, L. F. P.; Oliveira, C. J. B.; Medardus, J. J.; Molla, B. Z.; Wolfe, B. A.; Gebreyes, W. A.
Phenotypic and genotypic characterization of salmonella enterica in captive wildlife and exotic animal species in Ohio, USA
(Blackwell Verlag GmbH, 2015) Farias, L. F. P.; Oliveira, C. J. B.; Medardus, J. J.; Molla, B. Z.; Wolfe, B. A.; Gebreyes, W. A.
The purpose of this study was to investigate the occurrence, antimicrobial resis- tance patterns, phenotypic and genotypic relatedness of Salmonella enterica recovered from captive wildlife host species and in the environment in Ohio, USA. A total of 319 samples including faecal (n = 225), feed (n = 38) and envi- ronmental (n = 56) were collected from 32 different wild and exotic animal spe- cies in captivity and their environment in Ohio. Salmonellae were isolated using conventional culture methods and tested for antimicrobial susceptibility with the Kirby–Bauer disc diffusion method. Salmonella isolates were serotyped, and genotyping was performed using the pulsed-field gel electrophoresis (PFGE). Sal- monella was detected in 56 of 225 (24.9%) faecal samples; six of 56 (10.7%) envi- ronmental samples and six of 38 (15.8%) feed samples. Salmonella was more commonly isolated in faecal samples from giraffes (78.2%; 36/46), cranes (75%; 3/4) and raccoons (75%; 3/4). Salmonella enterica serotypes of known public health significance including S. Typhimurium (64.3%), S. Newport (32.1%) and S. Heidelberg (5.3%) were identified. While the majority of the Salmonella iso- lates were pan-susceptible (88.2%; 60 of 68), multidrug-resistant strains including penta-resistant type, AmStTeKmGm (8.8%; six of 68) were detected. Genotypic diversity was found among S. Typhimurium isolates. The identification of clon- ally related Salmonella isolates from environment and faeces suggests that indirect transmission of Salmonella among hosts via environmental contamination is an important concern to workers, visitors and other wildlife. Results of this study show the diversity of Salmonella serovars and public health implications of human exposure from wildlife reservoirs.
Prevalence and antimicrobial susceptibility profiles of Staphylococcus aureus from cow’s milk, nasal and environmental swabs in selected dairy farms in Morogoro, Tanzania
(Tanzania Veterinary Journal) Kashoma, I. P.; Lalata, E. P.; Maiga, C. J.; Mtemela, B. O.; Medardus, J. J.
Role of biocides in occurrence and persistence of biocide-tolerant and multi- drug resistant salmonellae
(Tanzania Veterinary Journal) Medardus, J. J.; Kazwala, R. R.; Gebreyes, W. A.
Role of biocides in occurrence and persistence of biocide-tolerant and multi- drug resistant salmonellae
(Tanzania Veterinary Journal) Medardus, J. J.; Kazwala, R. R.; Gebreyes, W. A.
Role of biocides in occurrence and persistence of biocide-tolerant and multi- drug resistant salmonellae
(Tanzania Veterinary Journal, 2020) Medardus, J. J.; Kazwala, R. R.; Gebreyes, W. A.
The aim of this study was to characterize the role of biocide interventions in the emergence of biocide-tolerant Salmonella, its co-selective association with multidrug-resistant Salmonella and the association with carriage of specific efflux gene markers. Salmonella isolates were detected in 13.9% (208/1,497) and 6.7% (98/1,468) of swine barn drag swab samples at pre- and post- disinfection with biocide, whereas, Salmonella isolates were detected in 17.2% (1,180/6,842) and 7.1% (431/6,093) of the early and late finishing pigs, respectively. Barn-level prevalence of antimicrobial resistance among Salmonella isolates recovered from the floor swab samples was 92.3% (1,503 of 1,628), whereas, the barn-level prevalence of antimicrobial resistance among Salmonella isolates recovered from the fecal samples was 98.02% (4,415 of 4,504). A total of 348 Salmonella isolates from swine barns formerly disinfected with Biosentry and 428 from swine barns disinfected with Synergize were subjected to minimum inhibitory concentration (MIC) testing for Biosentry and Synergize, respectively. In addition, selected Salmonella isolates were also genotyped to identify the carriage of quaternary ammonium compound (qac) tolerance genes. Interestingly, 22.9% (98 of 428) of Salmonella isolates from swine barns disinfected with Synergize carried the qac gene and the 86% of isolates that carried the qac gene also carried attenuated qacEΔ1. Nearly 31% (109 of 348) of Salmonella isolates from swine barns disinfected with Biosentry carried the qac gene. Furthermore, out of 109 Salmonella isolates that carried qac genes, 94.5% of the isolates contained attenuated qacEΔ1 gene, whereas 72.5% of the isolates carrying qacEΔ1 gene also carried class 1 integrons which is associated with both antibiotic and quaternary ammonium compound resistance. Although biocides are effective in limiting the growth, load and the colonization of bacterial pathogens, this study underscores the contribution of biocides in selective pressure towards antibiotic resistant in Salmonella.
Supplementation with quaternary benzo(c)phenanthridine alkaloids decreased salivary cortisol and salmonella shedding in pigs after transportation to the slaughterhouse
(Mary Ann Liebert, Inc.) Artuso-Ponte, V.; Moeller, S.; Rajala-Schultz, P.; Medardus, J. J.; Munyalo, J.; Lim, K.; Gebreyes, W. A.