Prevalence and Antimicrobial Resistance Pattern of Salmonella Isolates from Apparently Healthy Slaughtered Cattle in Ethiopia

The prevalence and antimicrobial resistance pattern of Salmonella isolates was determined from apparently healthy slaughtered cattle at Debre Zeit (Ethiopia). A total of 323 cattle were examined for the presence of Salmonella in faeces, mesenteric lymph nodes, abdominal and diaphragmatic muscles. Salmonellae were cultured from 23 (7.1%) of the animals. Salmonellae were isolated from 2 (3.1%) and 3 (4.5%) of 65 pooled faecal and mesenteric lymph node samples, respectively. Nine (2.8%) abdominal muscle and 10 (3.1%) diaphragmatic muscle samples (n = 323 of each) were contaminated by Salmonella. About 60% of the serovars identified in the abdominal and diaphragmatic muscles were also detected from faeces and mesenteric lymph node samples. The five different serovars isolated were Salmonella mishmarhaemek (48%), S. typhimurium (20%), S. enteritidis (12%), S. guildford (12%) and S. dublin (48%). The antimicrobial resistance profiles of 25 of the Salmonella isolates with 17 antimicrobials showed that 52% (13/25) of them were resistant to three or more antimicrobials. Both strains of Salmonella (S. mishmarhaemek and S. typhimurium) showed multiple resistance to ampicillin, sulfamethoxazole and ticarcillin. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antibiotic resistance pattern of foodborne Salmonella isolates in Addis Ababa (Ethiopia)

A total of 39 Salmonella cultures isolated from raw minced beef and chicken (gizzard, liver, and heart) samples in Addis Ababa were examined for susceptibility to a group of 10 selected antimicrobials. 34 isolates (87.2%) were resistant to one or more antibiotics. The antibiotics to which isolated Salmonella strains were most often fully resistant included nitrofurantoin (48.7%), furazolidone (48.7%) and streptomycin (46.2%). Only 4 antimicrobials (gentamycin, kanamycin, rifampicin and sulphamethoxazole-trimethoprim) were effective against all Salmonella isolates with the exception of 2 which were intermediate in resistance to kanamycin (1) and sulphamethoxazole-trimethoprim (1). 77.8% of the S. Enteritidis strains showed multiple resistance to up to four antibiotics followed by S. Typhimurium (60.0%) and S. Dublin (33.3%). The high level of antibiotic resistance of foodborne Salmonella isolates in the study area is an indication of indiscriminate and continuous use of subtherapeutic doses of antibiotics in animals.     

The characterization of Salmonella serovars isolated from apparently healthy slaughtered pigs at Addis Ababa abattoir, Ethiopia

We looked for Salmonella in all 278 apparently healthy pigs slaughtered between September 2004 and May 2005 at the only pig-slaughtering slaughterhouse in Addis Ababa, Ethiopia. We used standard methods and tested caecal contents, mesenteric lymph nodes, and carcass swabs from each pig (missing only one carcass swab). Of the 278 pigs, 120 (43%) were positive; of the 833 samples 173 (21%) were positive. Thirty-three percent of the isolates were multi-resistant (including 46/48 isolates of S. Hadar, but none of the 39 isolates of S. Eastbourne or of the 37 of S. Saintpaul). Resistance to streptomycin (32.4%), tetracycline (31.8%) and nitrofurantoin (27.2%) was relatively high. The most common pattern of MDR observed was to nitrofurantoin, streptomycin and tetracycline (Resistance type NitStrTet). Our results indicate that salmonellae are prevalent in pigs slaughtered at Addis Ababa abattoir and a large proportion of the isolates were multi-drug resistant.     

Antimicrobial susceptibility patterns of thermotolerant Campylobacter strains isolated from food animals in Ethiopia

Thermotolerant Campylobacter spp. are frequent causes of diarrhoea in humans worldwide mostly originating from poultry. It has been suggested that extensive veterinary use of antibiotics is largely responsible for resistance in human isolates. During a 4-month period from January to April 2004, 192 Campylobacter spp. were isolated from fecal samples of 485 healthy food animals. The in vitro susceptibility to 12 antibiotics was determined by the agar disk diffusion method. Among the 192 Campylobacter spp. isolated, 135 (70.3%) were identified to be C. jejuni, 51 (26.6%) were C. coli and 6 (3.1%) were C. lari. C. jejuni was the most prevalent species in chickens (80.8%) versus 16.2% C. coli and 3.0% C. lari. All isolates found in pigs were C. coli. All strains were sensitive to chloramphenicol and ciprofloxacin and all were resistant to cephalothin. More than 90% of the strains were sensitive to clindamycin, erythromycin, gentamicin, nalidixic acid, norfloxacin, streptomycin and tetracycline. Resistance was found against ampicillin in 20% and trimethoprim-sulphamethoxazole in 37.5%. Resistance was not statistically different among C. jejuni, C. coli and C. lari (p>0.05). Multidrug resistance to two or more drugs was detected in 14.5% of strains. In conclusion, the study showed that antimicrobial resistance is found only at relatively low frequencies for most antimicrobial agents tested except for ampicillin and trimethoprim-sulphamethoxazole. The low percentages of resistance to most antimicrobial agents tested in this study may be the result of low/no usage of these agents as a growth promoters or treatment in the Ethiopian animal farm setting. The detection of multidrug resistant isolates may pose a threat to humans and further limits therapeutic options.     

Occurrence and antimicrobial resistance of Salmonella serovars in apparently healthy slaughtered sheep and goats of central Ethiopia

The present study was undertaken to determine the occurrence, distribution and antimicrobial resistance pattern of Salmonella serovars in apparently healthy slaughtered sheep and goats in central Ethiopia. A total 1224 samples consisting of faeces, mesenteric lymph nodes, liver, spleen, and abdominal and diaphragmatic muscle samples were collected from 104 sheep and 100 goats. Salmonella was isolated from 12 of 104 (11.5%) sheep and 3 of 100 (3%) goats. Of the total 624 and 600 samples examined from sheep and goats, 18 (2.9%) and 4 (0.7%), respectively, were Salmonella positive. The 22 Salmonella isolates belonged to 9 different serovars. The common serovars isolated were S. typhimurium, followed by S. heidelberg, S. reading, S. give, and S. poona. Seven of the 22 isolates (31.8%) were multidrug-resistant to various antimicrobials.     

Antimicrobial resistance pattern of Salmonella serotypes isolated from apparently healthy slaughtered camels (Camelus dromedarius) in eastern Ethiopia

A total of 714 samples consisting of faeces, mesenteric lymph nodes, liver, spleen, abdominal and diaphragmatic muscles (each 119) were collected from November 2001 to April 2002 from apparently healthy slaughtered camels (Camelus dromedarius) in eastern Ethiopia. One hundred sixteen (16.2%) Salmonella strains belonging to 16 different serovars were isolated. All Salmonella strains isolated were examined for antimicrobial resistance to 17 selected antimicrobials. The minimum inhibitory concentration (MIC) values were determined by the microdilution broth test. Fifty-two (44.8%) of the Salmonella isolates were resistant to one or more antimicrobials. Thirty-nine of the 52 (75%) resistant Salmonella serovars exhibited multiple resistance to up to eight different antimicrobials. Among the serovars tested, S. Typhimurium, S. Heidelberg, S. Braenderup and S. Hadar displayed multiple resistance mainly to streptomycin (35.3%), spectinomycin (28.4%), sulfamethoxazole (25.0%), ampicillin (24.1%), trimethoprim (22.4%), trimethoprim/sulfamethoxazole (18.9%), tetracycline (12.9%) and colistin (11.2%). All Salmonella strains tested were susceptible to ciprofloxacin, nalidixic acid, gentamicin, kanamycin and neomycin. The present study showed the importance of camels as a potential source of single and multiple resistant Salmonella strains to different antimicrobials that are also used in the public health sector for the treatment of different bacterial diseases in Ethiopia.     

Current status of bovine cysticercosis of slaughtered cattle in Addis Ababa Abattoir,Ethiopia

The prevalence of Taenia saginata cysticercosis in cattle slaughtered for meat in Addis Ababa Abattoir, Ethiopia between September 2004 and August 2005 was reported. The examination of various organs of 11227 cattle in Addis Ababa Abattoir showed that 842 (7.5%) were infected with T. saginata cysticercosis. The tongue, masseter muscles, cardiac muscles, triceps muscles and thigh muscles were the main predilection sites of the cysts. The cysts of bovine cysticercosis were also identified on the spleen, intercostal muscles, diaphragm and liver. Out of 10329 male cattle, examined, 783 (7.6%) had cysts of bovine cysticercosis while 59 (6.6%) of the 898 female animals investigated were infected. The animals slaughtered were all adults. No significant difference in prevalence rates was recorded between the sexes. The prevalence of bovine cysticercosis was higher in local zebu cattle breeds than Holstein-Frisian cattle.     

Field trial evaluating changes in prevalence and patterns of antimicrobial resistance among Escherichia coli and Enterococcus spp. isolated from growing broilers medicated with enrofloxacin, apramycin and amoxicillin

The present study investigates, under field conditions, the influence of antimicrobial administration on prevalence and patterns of antimicrobial resistance among Escherichia coli and Enterococcus spp. isolated from growing broilers. For this purpose, a group of 16,000 commercial broiler chickens was treated with enrofloxacin from day 1 to day 3, gentamicin from day 19 to day 21, and ampicillin from day 26 to day 28. A control group of 16,000 broilers was placed in the same controlled environment poultry house. Fecal (from both groups) and feed samples were collected at regular intervals. Few E. coli isolates were obtained from either farm environment or poultry feed samples, while enterococci were found to be ubiquitous among these samples. The frequency of resistance against most antimicrobials tested was significantly higher (P < 0.05) in E. coli isolated from broilers receiving intermittent antimicrobial pressure than that from non-medicated broilers, whereas in enterococci these differences were only observed among structurally related antimicrobial drugs and over a short period of time. By the time the broilers reached market age (33 days), several multi-resistant E. coli and enterococci were detected in the feces of the medicated group. Results suggest that antimicrobial resistance in E. coli was mainly medication-dependent, whereas among enterococci, changes observed over time were apparently influenced by factors apart from antimicrobial exposure, namely the resistance organisms previously present in farm environment and those present in feedstuffs.     

Phenotypic and genetic characterization of Salmonella enterica subsp. enterica serovar Typhimurium isolated from pigs in Rio Grande do Sul, Brazil

This study aimed to investigate the relatedness of porcine Salmonella enterica subsp. enterica (S.) serovar Typhimurium strains isolated in Southern Brazil. Sixty-six isolates from pigs belonging to three commercial companies were submitted to phage typing, XbaI-macrorestriction (PFGE), IS200 hybridization, rep-PCR, antimicrobial susceptibility testing, and PCR assay targeting the spvR region. All strains presented a unique rep-PCR pattern and 63 strains had a common IS200 profile. One pulse-type (XA) was the most prevalent (39/66 strains) and included strains of phage types DT177, DT192, DT194 and RDNC. The spvR region was detected in three strains, which harboured plasmids of 90 kb. High rates of tetracycline, sulfonamide and streptomycin resistance were found. Isolates from farms located in different geographic regions but associated to the same commercial companies clustered together and presented a common resistance profile. Results suggested that clonal groups of S. Typhimurium are present in pig commercial companies in Southern Brazil.     

Identification of Salmonella spp. isolates from chicken abattoirs by multiplex-PCR

The present study was carried out to report the occurrence Salmonella spp., Salmonella Enteritidis, and Salmonella Typhimurium in chicken abattoirs. Samples of feces; feathers; scald, evisceration, and chiller water; and rinse water of non-eviscerated, eviscerated, and chilled carcass were collected from six chicken abattoirs. Salmonella isolates were identified by a multiplex-PCR using three sets of primers targeting the invA, pefA, and sefA gene sequences from Salmonella spp., S. Typhimurium and S. Enteritidis, respectively. Salmonella spp. was detected in 10% (29/288) of the samples, whereas serovars Enteritidis and Typhimurium were identified in 62% (7/288), respectively. The results indicate the need to improve hygiene and sanitary standards in poultry slaughter lines, besides the education of food handlers and information to consumers.     

Contamination of Salmonella spp. in a pig finishing herd, from the arrival of the animals to the slaughterhouse

The aim of the present study was to investigate the contamination sources and the transmission of Salmonella within a pig finishing herd in Italy. Nine sets of samples were collected during the fattening period from cleaned and disinfected pens, animals at different ages (4 days after arrival, 90, 150, 170 and 240 days of age) and at slaughter. Salmonella was isolated from cleaned pens, individual faecal samples, the truck used to transport the pigs to the abattoir and after slaughter (cecal contents, mesenteric lymph nodes and carcasses). Several serovars were isolated: Salmonella typhimurium and Salmonella derby on farm; Salmonella bovismorbificans, Salmonella bredeney, Salmonella blockley, Salmonella hadar and Salmonella corvallis from the truck; S. derby, S. hadar, S. bredeney, S. bovismorbificans and Salmonella infantis at slaughter. Antibiotic resistance of the strains was tested and PFGE was carried out to investigate the on-farm epidemiology of Salmonella. The results showed that the environmental contamination may have represented a major source of infection for the pigs both on farm and during transport to the abattoir.     

Salmonella Prevalence and Distribution of Serotypes in Apparently Healthy Slaughtered Camels (Camelus dromedarius) in Eastern Ethiopia

The present study was undertaken to determine the prevalence and distribution of Salmonella from apparently healthy slaughtered camels in Eastern Ethiopia. A total of 714 samples (faeces, mesenteric, lymph nodes, spleen, liver, abdominal and diaphragmatic muscles) from 119 slaughtered camels were analysed. Salmonellae were detected from 116 (16.2%) of the 714 samples examined. Eighteen (15.1%) faeces, 19 (15.9%) mesenteric lymph nodes, 14 (11.8%) livers and 17 (14.3%) spleen samples (n = 119 for each) were positive for Salmonella. Salmonellae were found in 20.1% of the abdominal and diaphragmatic muscles. A total of sixteen different serotypes were identified of which Salmonella saintpaul (38.8%) and S. braenderup (22.4%) were the most prevalent followed by S. muenchen (8.6%), S. kottbus (6.0%) and S. havana (5.2%). Other serotypes, including S. typhimurium, S. heidelberg and S. enteritidis were also detected from Ethiopian camels.     

Molecular and virulence characteristics of multi-drug resistant Salmonella Enteritidis strains isolated from poultry

Forty-six Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) strains were isolated from chicken meat, faeces, and eggshells collected from hatcheries throughout Korea. The strains were examined for the presence of antimicrobial resistance and virulence genes. All 46 isolates were resistant to at least one of 21 antibiotics used in this study, 30 (65.2%) were resistant to three or more antimicrobials, and a single remarkable isolate was resistant to 15 antimicrobials. The isolates were primarily resistant to penicillins, sulfisoxazole, streptomycin, tetracycline and quinolones.The high rate of resistance in S. Enteritidis strains, sometimes to multiple drugs, may complicate future options for treating human infections. Nineteen of the 21 penicillin resistant isolates carried the bla_TEM gene, while one strain, resistant both to penicillins and ceftriaxone, carried the bla_CTX-M gene. Thirty-seven of the 45 sulfisoxazole resistant isolates carried sul2, and 23/24 streptomycin resistant isolates carried both strA and strB. All 10 tetracycline resistant isolates carried the tet(A) gene. Most isolates harboured both SPI-1 and SPI-2-associated genes, and the spv operon, which are known to be associated with human infections. The presence of these genes suggests that these strains could give rise to public health problems if dispersed in the general human population.     

Amino acid substitutions in gyrA and parC associated with quinolone resistance in nalidixic acid-resistant Salmonella isolates

This study was undertaken to identify and characterize amino acid substitutions in gyrA and parC related with quinolone resistance of 27 nalidixic acid-resistant (Na^R) Salmonella isolates collected in poultry slaughterhouses in Korea. A total of 51 Salmonella isolates were detected from 44.8% (47/105) of the total samples from 15 poultry slaughterhouses examined, among which 27 (52.9%) Na^R isolates were detected while ciprofloxacin (Cip) resistance was not present in the isolates. These 27 Na^R isolates of DNA sequencing revealed that it contained three types of gyrA mutations in only D87 codon. Mutations in the D87 codon resulted in substitutions to G in most of the isolates, but D87Y and D87N exchanges were also detected. Although Cip resistance was absent, reduced susceptibility characterized by mutations in gyrA was apparent among Salmonella isolates from poultry slaughterhouses in Korea.     

Antimicrobial susceptibility and tetracycline resistance determinant genotyping of Gallibacterium anatis

The present investigation was undertaken to assess the antimicrobial susceptibility of a collection of 58 Gallibacterium isolates. All strains were tested by the broth dilution method using the veterinary fastidious medium. A total of 46 field strains were tested, whereof 23 were clinical isolates from 10 Mexican layer flocks and another 23 isolates originated from 13 clinically healthy poultry flocks in Denmark. In addition, 12 Gallibacterium reference strains that had been isolated some 30–40 years ago were included.     

四川省动物性食品源沙门氏菌的耐药性监测与分析

近年食源致病菌耐药性较严重,为了解四川省动物性食品源沙门氏菌（Salmonella spp.）耐药情况,本试验采用肉汤微量稀释法,对源自四川省动物性食品的76株沙门氏菌进行了25种抗生素(组合)的敏感性试验。结果表明76株沙门氏菌对利福平（96.05%）、黏菌素（78.95%）、磺胺异噁唑（64.47%）、先锋唑啉（60.53%）、氨苄西林（60.53%）、阿莫西林—克拉维酸（56.58%）、甲氧苄啶（53.95%）及强力霉素（52.63%）耐药率较高。76株沙门氏菌对25种抗生素（组合）共产生了66种耐药谱,多重耐药率达97.37%（74/76）,主要对青霉素类、先锋唑啉、链霉素、四环素类、磺胺类药物及黏菌素表现出多重耐药。结果表明,四川地区食源沙门氏菌耐药性已较为严重,应加强连续监测。     

Antimicrobial resistance of selected Salmonella isolates from food animals and food in Alberta

Salmonella isolates (n = 209) obtained from food animals and foods in Alberta during 1996 through 1999 were tested for sensitivity to 17 antimicrobials. Of the 3553 antimicrobial susceptibility tests on Salmonella isolates, 11.8% were positive for resistance. These isolates were commonly resistant to tetracycline (35.4%), streptomycin (32.5%), sulfamethoxazole (28.7%), ticarcillin (27.3%), and ampicillin (26.8%). Resistance to at least 1 antimicrobial was observed in 112 isolates (53.6%). Salmonella Typhimurium, S. Typhimurium var. Copenhagen, and S. Heidelberg were the most common serovars among isolates resistant to individual antimicrobials and multiple antimicrobials. The most common profile of multiple-antimicrobial resistance was that which included resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline, and ticarcillin. The proportions of isolates that were resistant to antimicrobials were greater among bovine isolates of Salmonella than among poultry isolates, and this difference was greater among isolates from veterinary diagnostic sources than among those from monitoring sources.     

Resistance phenotypes and genotypes among multiple-antimicrobial-resistant Salmonella enterica subspecies enterica serovar Choleraesuis strains isolated between 2008 and 2012 from slaughter pigs in Okinawa Prefecture,Japan

A total of 349 Salmonella enterica subspecies enterica serovar Choleraesuis (S. Choleraesuis) strains, which were isolated between 2008 and 2012 from 349 pigs at two slaughterhouses in Okinawa Prefecture, Japan, were investigated for antimicrobial susceptibility and the presence of antimicrobial resistance genes. All isolates were resistant to at least four antimicrobial agents. The antimicrobial agents for which isolates showed a high incidence of resistance were as follows: ampicillin (100%) and streptomycin (100%), followed by gentamicin (99.7%), oxytetracycline (99.7%), sulfamethoxazole/trimethoprim (99.4%), nalidixic acid (40.1%) and oxolinic acid (40.1%). All isolates were sensitive to cefuroxime, ceftiofur, colistin, fosfomycin, enrofloxacin, orbifloxacin and danofloxacin. The predominant resistance phenotypes and genotypes were: resistance to ampicillin, streptomycin, gentamicin, oxytetracycline and sulfamethoxazole/trimethoprim (58.5%, 204/349) and blaTEM-strA-strB-aadA1-aadA2-aacC2-tet (B)-sul1-sul2-dhfrXII-dhfrXIII (36.1%, 126/349). The quinolone resistance-determining regions (QRDRs) of gyrA, gyrB, parC and parE of the quinolone-resistant isolates (n=12) showed amino acid substitutions of Ser-83→Phe or Asp-87→Tyr in GyrA and Ser-107→Ala in ParC. To our knowledge, this is the first report on the molecular characterization of antimicrobial resistance among S. Choleraesuis strains in Japan.