Browsing by Author "Medardus, J. J."
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Item 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.Item Citrobacter as a gastrointestinal pathogen, its prevalence and molecular characterization of antimicrobial resistant isolates in food-producing animals in Morogoro, Tanzania(TANZANIA VETERINARY ASSOCIATION, 2017) Medardus, J. J.Citrobacter is a gastrointestinal commensal of man and animals. The zoonotic Citrobacter spp. infection can occur if food products of animal origin are not hygienically handled. Therefore, the prevalence, antimicrobial resistance profile and resistance transmission mechanism of Citrobacter spp. in food-producing animals in Tanzania needs to be understood. Citrobacter isolates were recovered from 2.4% of the total of 1099 samples from apparently healthy animals. Citrobacter isolates were detected in 3.0% and 1.9% of the swine and the cattle samples, respectively. Over 80% of food products contamination with Citrobacter isolates originated from slaughtered cattle carcasses just before meat is transported to retail stores. About 62% of the isolates detected were resistant to at least one antimicrobial, whereas, 38.5% of the resistant isolates were exhibiting resistance to three or more antibiotic classes. All 26 presumptive Citrobacter isolates were screened for invA, intI1 and 16S rRNA. None of the isolates carried invA. Nearly 19% of the MDR Citrobacter isolates were found to carry an intI1. All intI1-positive isolates contained resistance gene cassettes dfrA1, dfrA7 and dfrA15. Detection of resistance gene cassettes in the MDR Citrobacter isolates in animals and animal products represents a potential source for horizontal transfer of antimicrobial resistance genes and mobile genetic elements between pathogenic and non-pathogenic bacteria in the microbial population. The findings indicate that animal feces could one of the potential sources for contamination of animal products along the food production chain.Item 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.Item 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., 2019) Apruzzese, I.; Song, E.; Bonah, E.; Sanidad, V. S.; Leekitcharoenphon, P.; Medardus, J. J.; Abdalla, N.; Hosseini, H.; Takeuchi, M.Whole-genome sequencing (WGS) has become a significant tool in investigating foodborne disease outbreaks and some countries have incorporated WGS into national food control systems. However, WGS poses technical chal- lenges that deter developing countries from incorporating it into their food safety management system. A rapid scoping review was conducted, followed by a focus group session, to understand the current situation regarding the use of WGS for foodborne disease surveillance and food monitoring at the global level and identify key limiting factors for developing countries in adopting WGS for their food control systems. The results showed that some developed nations routinely use WGS in their food surveillance systems resulting in more precise understanding of the causes of outbreaks. In developing nations, knowledge of WGS exists in the academic/research sectors; however, there is limited understanding at the government level regarding the usefulness of WGS for food safety regulatory activities. Thus, incorporation of WGS is extremely limited in most developing nations. While some countries lack the capacity to collect and analyze the data generated from WGS, the most significant technical gap in most developing countries is in data interpretation using bioinformatics. The gaps in knowledge and capacities between developed and developing nations regarding use of WGS likely introduce an inequality in international food trade, and thus, relevant international organizations, as well as the countries that are already proficient in the use of WGS, have significant roles in assisting developing nations to be able to fully benefit from the technology and its applications in food safety management.Item Molecular characterization of multidrug resistant salmonella isolates from food animals and animal products in Tanzania(Tanzania Veterinary Journal, 2020) Medardus, J. J.; Gebreyes, W. A.Food animals are major sources of human salmonellosis. Animals raised for food play an important role in transmission of antimicrobial resistant Salmonella strains to humans. The aim of this study was to determine the antimicrobial resistance profile, the occurrence of class 1 integrons and the resistance gene cassettes mobilized in the class 1 integrons of Salmonella isolates. A cross-sectional design was carried out in pastoral regions of Tanzania with large population of livestock. Salmonella isolates were recovered from 4.2% of the total of 1540 samples from apparently healthy animals and the animal products. The results showed that Salmonella isolates were detected in 5.2%, 3.7% and 3.8% of the swine, cattle and chicken, respectively. Sixty-one Salmonella isolates belonged to Salmonella enterica subsp. enterica. Predominant serotypes were Salmonella I 8,20:i:- (32.8%), S. Hadar (10.9%), S. Colindale (6.3%), S. Anatum (6.3%) and S. Heidelberg (6.3%). S. I 8,20:i:- isolates were widespread in different samples from different food animals. Of 64 Salmonella isolates, about 35.9% were resistant to at least one antimicrobial, whereas, 82.6% were multi-drug resistant (MDR) Salmonella. About 8.7% of the MDR Salmonella isolates were found to also carry integrons (intI1) and 100% of intI1-positive isolates contained resistance gene cassettes known as aac(3)-Id-aadA7 showing high rate of MDR. The occurrence of clonal MDR Salmonella isolates in food animals and animal products from pastoral communities indicates the high significance of informal traditional sector as an important source of foodborne pathogens in the food chain and the entry of pathogens to the pastoralist communities.Item 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.Item 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, 2015-07-25) Kashoma, I. P.; Lalata, E. P.; Maiga, C. J.; Mtemela, B. O.; Medardus, J. J.Staphylococcus aureus is a microorganism that is present as a commensal on the skin, the nose and mucous membranes of healthy humans and animals. However, it is also an opportunistic pathogen that can cause multiple infectious diseases of diverse severity. A cross-sectional study was carried out to determine the prevalence and antimicrobial resistance profiles of S. aureus from samples of cow’s milk, farm environmental and cattle nasal swabs from three dairy farms in Morogoro.A total of 377 samples; raw milk (n = 100), nasal swabs (n=133) and environmental swabs (n = 144) were screened for the presence of S. aureus.California mastitis test (CMT) was used to establish the status of mastitis. Gram staining, oxidase, catalase, DNase, haemolysis and coagulase tests were employed for bacterial identification. Antimicrobial susceptibility testing was conducted using the Kirby- Bauer disk diffusion assay. Out of 200 cows (800 quarters milk) CMT screened for mastitis, (12.5%) quarters from 80 cows tested positive for subclinical mastitis, while twelve (1.5%) quarters from seven (3.5%) cows tested positive for clinical mastitis.Overall, 97 (25.7%) of 377 samples were positive for S. aureus, which were detected in 49.0%, 11.6%, and 40.0% of the milk, environment and nasal samples, respectively.Antimicrobial susceptibility testing revealed resistance to: Ampicillin (67.4%), Cefoxitin (14.8%), Erythromycin (21.1%), Gentamycin (3.2%), Oxacillin (37.9%), Tetracycline (55.8%), Trimethoprime-Sulfamethoxazole (29.5%) and Vancomycin(9.5%). 28.4% (n=27) of all isolates were resistant to Oxacillin and/or Cefoxitin, and therefore classified as Methicillin-Resistant Staphylococcus aureus(MRSA). 63%of the MRSA isolates originated from milk, 22.2% from nares and 14.8% from environmental samples. Over a half of all isolates were classified as multidrug resistant;of these 43.2% (n=41), 6.3% (n=6) and 1.1% (n=1) were simultaneously resistant to three, four and five antimicrobial agents, respectively. Taken together, this study revealed the prevalence of multidrug resistant S. aureus in cow’s milk, nares and farm environment. Our findings also confirm the presence of livestock-associated MRSA, and thus underline the importance of applying biosecurity measures and good hygiene practices to prevent MRSA spread at the farm level and throughout the food production chain.Item 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.Item 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.Item Supplementation with quaternary benzo(c)phenanthridine alkaloids decreased salivary cortisol and salmonella shedding in pigs after transportation to the slaughterhouse(Mary Ann Liebert, Inc., 2015) Artuso-Ponte, V.; Moeller, S.; Rajala-Schultz, P.; Medardus, J. J.; Munyalo, J.; Lim, K.; Gebreyes, W. A.The present study was aimed at evaluating the effect of herbal extracts supplementation, particularly quaternary-benzo(c)phenanthridine alkaloids (QBA), which have been previously demonstrated to have anti- inflammatory, antimicrobial, and immune-modulator effects. We investigated the role of QBA on stress re- sponse and Salmonella shedding in finishing pigs transported to the slaughterhouse. A total of 82 pigs were orally challenged with a Salmonella cocktail (day 0) containing Salmonella Meleagridis, Hartford, Bo- vismorbificans and Newport serovars and randomly assigned to three treatment groups after 2 wks (day [D] 14): T1, in-feed QBA; T2, in-feed and water-soluble QBA; CON, nonsupplemented). Pigs were transported to the slaughterhouse 2 weeks after intervention (D 28) and slaughtered after nearly 19 h (D 29). Saliva, fecal samples, and carcass swabs were collected from all pigs. Salivary cortisol, Salmonella shedding, and carcass contami- nation were measured. A high positive correlation (Spearman rank correlation coefficient range 0.82–0.93) between salivary cortisol and Salmonella shedding was found after transportation in all groups ( p < 0.05). Only the CON group showed an increase in salivary cortisol after transportation (5.48 ng/mL; p < 0.0001) to con- centrations that were higher than in T1 (2.73 ng/mL; p = 0.0002) and T2 (1.88 ng/mL; p < 0.0001). Salmonella prevalence and shedding decreased after transportation in pigs receiving the QBA intervention ( p < 0.05), whereas the control group showed a significant increase in Salmonella shedding after transportation ( p = 0.04). At D 28, pigs in T2 shed lower numbers of Salmonella as compared to T1 (1.3E + 02 CFU/mL versus 8E + 03 CFU/mL; p = 0.002). Additionally, carcass contamination by Salmonella was higher in the CON group than the treated groups ( p = 0.01). The findings show QBA intervention was effective in reducing transportation stress of pigs, resulting in reduced Salmonella shedding and positively impacting animal welfare and pork safety.