Immunopotentiation of a Developed Salmonella enterica serotype Enteritidis Vaccine by Thymulin and Zinc in Meat Chicken Breeders

The humoral immunity, spleen and thymus weight indices, lymphocyte count in the thymus cortex, and granuloma diameter at vaccination sites were assessed in four differently immunopotentiated groups of meat chicken breeders. Breeders in the first two groups were given a killed Salmonella enterica serotype Enteritidis (SE) vaccine subcutaneously at 15 and 19 weeks of age. Breeders in the third and fourth groups were left unvaccinated. Breeders in the first group were further immunopotentiated with zinc and thymulin. Each bird in the first group was given the immunopotentiators intraperitoneally in a volume of 0.1 ml at intervals of 3 days for a period of 3 weeks, starting at 15 weeks of age. At each time, each bird in the first group received thymulin (10 ng) and ZnCl₂ (1 mol/L), using a carboxymethyl cellulose carrier, totalling 90 ng thymulin and 9 mol of ZnCl₂ per bird. Each bird in the first three groups was challenged orally with 6.7×10⁶ cfu/ml of highly virulent SE organisms, at an age of 22 weeks. The first group, which had received zinc and thymulin, had the earliest and highest humoral immune response to SE (p<0.05). This was observed at 2 and 4 weeks after the first vaccination. In addition, the first group had the highest mean thymus weight index, and the highest mean lymphocyte count in the thymus cortex. No significant difference was observed between the first two vaccinated groups in the mean granuloma diameter developed at the two vaccination sites 48 h after administration of the vaccine (p>0.05).     

Molecular typing of Salmonella enterica serovar Enteritidis isolates from food-producing animals in Japan by multilocus variable-number tandem repeat analysis: evidence of clonal dissemination and replacement

Background

Salmonella enterica serovar Enteritidis is a zoonotic pathogen. Human infections are associated with contaminated eggs and egg products. In Japan, since 1989, the incidence of food-borne disease caused by S. Enteritidis has increased and a pandemic has occurred; however, little is known about changes that occurred before and after this pandemic event in the dominant lineage of isolates from food-producing animals. This study aimed to determine the S. Enteritidis lineages in Japan over the last few decades by using multilocus variable-number tandem repeat analysis (MLVA).

Findings

MLVA was used to analyse 79 S. Enteritidis isolates collected from chickens (n = 63), cattle (n = 12), pigs (n = 2), and goats (n = 2) during 1975–2009. The S. Enteritidis isolates showed 14 different MLVA allele combinations, which were classified into two major clusters (A and C) and a minor cluster (B). All the 62 isolates in cluster A were isolated after 1988, whereas 13 of the 17 isolates belonging to cluster B and C were isolated before 1989.

Conclusions

The MLVA results showed that cluster C was predominant before 1989, and isolates in cluster A disseminated since 1989 and replaced the previous dominant clone, suggesting that isolates of cluster A originated from imported S. Enteritidis infection.     

The role of rpoS,hmp, and ssrAB in Salmonella enterica Gallinarum and evaluation of a triple-deletion mutant as a live vaccine candidate in Lohmann layer chickens

Salmonella enterica Gallinarum (SG) causes fowl typhoid (FT), a septicemic disease in avian species. We constructed deletion mutants lacking the stress sigma factor RpoS, the nitric oxide (NO)-detoxifying flavohemoglobin Hmp, and the SsrA/SsrB regulator to confirm the functions of these factors in SG. All gene products were fully functional in wild-type (WT) SG whereas mutants harboring single mutations or a combination of rpoS, hmp, and ssrAB mutations showed hypersusceptibility to H₂O₂, loss of NO metabolism, and absence of Salmonella pathogenicity island (SPI)-2 expression, respectively. A triple-deletion mutant, SGΔ3 (SGΔrpoSΔhmpΔssrAB), was evaluated for attenuated virulence and protection efficacy in two-week-old Lohmann layer chickens. The SGΔ3 mutant did not cause any mortality after inoculation with either 1 × 10⁶ or 1 × 10⁸ colony-forming units (CFUs) of bacteria. Significantly lower numbers of salmonellae were recovered from the liver and spleen of chickens inoculated with the SGΔ3 mutant compared to chickens inoculated with WT SG. Vaccination with the SGΔ3 mutant conferred complete protection against challenge with virulent SG on the chickens comparable to the group vaccinated with a conventional vaccine strain, SG9R. Overall, these results indicate that SGΔ3 could be a promising candidate for a live Salmonella vaccine against FT.     

A multiplex real-time PCR for differential detection and quantification of Salmonella spp., Salmonella enterica serovar Typhimurium and Enteritidis in meats

Salmonella (S.) Typhimurium and S. Enteritidis are the major causative agents of food-borne illnesses worldwide. Currently, a rapid detection system using multiplex real-time polymerase chain reaction (PCR) has been applied for other food-borne pathogens such as Escherichia coli, Staphylococcus aureus and Streptococcus spp. A multiplex real-time PCR was developed for the simultaneous detection of Salmonella spp., especially S. Typhimurium and S. Enteritidis, in beef and pork. For the specific and sensitive multiplex real-time PCR, three representative primers and probes were designed based on sequence data from Genbank. Among the three DNA extraction methods (boiling, alkaline lysis, and QIAamp DNA Mini Kit), the QIAamp DNA Mini Kit was the most sensitive in this study. The optimized multiplex real-time PCR was applied to artificially inoculated beef or pork. The detection sensitivity of the multiplex real-time PCR was increased. The specificity of the multiplex real-time PCR assay, using 128 pure-cultured bacteria including 110 Salmonella isolates and 18 non-Salmonella isolates, was 100%, 100% and 99.1% for Salmonella spp., S. Typhimurium and S. Enteritidis, respectively. The sensitivity was 100%, 100% and 91.7% for Salmonella spp., S. Typhimurium and S. Enteritidis, respectively. The multiplex real-time PCR assay developed in this study could detect up to 0.54 ± 0.09 and 0.65 ± 0.07 log₁₀ CFU/ml for S. Typhimurium and S. Enteritidis for beef, 1.45 ± 0.21 and 1.65 ± 0.07 log₁₀ CFU/ml for S. Typhimurium and S. Enteritidis for pork, respectively, with all conditions optimized. Our results indicated that the multiplex real-time PCR assay developed in this study could sensitively detect Salmonella spp. and specifically differentiate S. Typhimurium from S. Enteritidis in meats.     

Passive protection against Salmonella enterica serovar Enteritidis infection from maternally derived antibodies of hens vaccinated with a ghost vaccine

This study evaluated maternal immunity against Salmonella enterica serovar Enteritidis acquired through the egg yolk. Two-hundred 19-week-old specific pathogen free (SPF) broiler breeders which were randomly divided into two groups of equal size were injected with S. Enteritidis ghosts (5 × 10⁹ colony forming units in 0.1 ml per hen) and phosphate-buffered saline (PBS, 0.01 mol⋅l⁻¹, pH 7.4) twice, respectively, with an interval of 2 weeks. An indirect enzyme-linked immunosorbent assay (ELISA) was applied to detect specific antibodies against S. Enteritidis. S. Enteritidis-specific antibody levels in the vaccinated group increased over time and were significantly higher than those of the control group on days 28 (P < 0.001) and 35 (P < 0.001) post-vaccination. Ten 7-day-old chicks from hens that were vaccinated with a S. Enteritidis ghost vaccine were challenged at 14 days of age with 5 × 10⁹ CFU of S. Enteritidis DH091 (homologous to the vaccine strain), 8/10 (80%) chicks from vaccinated hens survived, whereas 3/10 (30%) chicks from unvaccinated hens survived. The chicks acquired high levels of serum antibodies against S. Enteritidis. These results reveal that maternal antibodies in chicks acquired from vaccinated hens through eggs can confer a significant protection against S. Enteritidis infection.     

1株鸡源肠炎沙门氏菌的分离鉴定及致病性分析

【目的】确定云南某蛋鸡场送检的疑似沙门氏菌病病料中的主要病原菌种类,并测定其致病性及药物敏感性。【方法】通过细菌分离培养、形态观察、生化试验、血清学鉴定及分子学方法进行细菌分离鉴定;通过对鸡的致病性试验及毒力基因检测分析分离菌的致病性;通过药物敏感性试验检测分离菌耐药情况。【结果】分离菌株在沙门氏菌显色培养基上形成紫色菌落,镜检为革兰氏阴性短杆菌,疑为沙门氏菌,命名为S2;生化试验结果显示,菌株S2赖氨酸脱羧酶、硫化氢、卫矛醇试验结果均为阳性;靛基质、尿素酶、氰化钾、山梨醇、水杨苷、β-半乳糖苷、丙二酸盐生化试验结果均为阴性,判断菌株S2为典型沙门氏菌属;血清学鉴定结果显示,菌株S2属于D群肠炎沙门氏菌,其抗原式为1,9,12:g,m;遗传进化分析结果显示,菌株S2与肠炎沙门氏菌MT621365处于同一分支,自展值为99%;致病性试验结果表明,分离菌株对雏鸡有较强的致病性,感染6 d后雏鸡全部死亡(10/10);毒力基因检测结果显示,菌株S2携带invJ、hilA、ssaB、misL、mgtC、orf319、sopB、spvA、spvB、spvC、spvR、stn和fimA毒力基因,不携带sopA、fliC毒力基因;菌株S2对多数抗菌药敏感程度很高,对阿莫西林-克拉维酸、头孢西丁、四环素等12种抗菌药均敏感,对甲氧嘧啶、复方新诺明和林可霉素耐药。【结论】本研究分离到了1株肠炎沙门氏菌,其毒力较强,可造成雏鸡较高的死亡率,对大部分常用抗菌药敏感,对甲氧嘧啶、复方新诺明和林可霉素具有耐药性。本研究结果可为沙门氏菌病的临床诊断和药物有效性评价提供一定参考依据。     

广东省广州市猪禽屠宰场环境沙门氏菌血清分型与耐药性分析

为了解广东省广州市屠宰环节环境中沙门氏菌血清型分布及其耐药性,对广州市大型生猪、家禽屠宰企业环境进行监控,对比分析猪禽屠宰场污染的沙门氏菌主要血清型和耐药谱.采集屠宰场的空气、土壤、污泥样品,以及运输车辆、待宰圈/舍、屠宰车间等环境拭子样品,利用沙门氏菌特异性引物进行PCR扩增和测序鉴定;通过玻片凝集法,对PCR鉴定阳...     

Improvement of bacterial clearance and relief of clinical signs of Salmonella enterica serovar Typhimurium infection in pigs through upregulation of Th 1-specific responses by administration of a combination of two silicate minerals,biotite and bentonite

Biotite and bentonite are phyllosilicate minerals that were originally used inindustrial applications. Several beneficial activities of them have recently beenreported, especially regulation of the immune system and antimicrobial effects. Therefore,we investigated the immune-enhancing and bacterial clearance effects of a biotite andbentonite mixture (BBM) on experimental infection of Salmonella entericaserovar Typhimurium (S. Typhimurium) to determine whether the BBM couldbe used as an alternative antibiotic. We administered 1% or 2% BBM as a feed supplement.We then evaluated the bacterial clearance effects of the BBM against S.Typhimurium. We also evaluated the immune-enhancing effect of the BBM through severalimmunological experiments that included examination of the lysozyme activity,CD4⁺/CD8⁺ T lymphocyte ratio and the T-helper type 1 (Th 1)cytokine profile. The clinical signs of S. Typhimurium and the number ofviable bacteria in feces and tissues were significantly decreased in both BBM groups,especially in the 2% BBM group. The BBM also markedly enhanced the lysozyme activity,CD4⁺/CD8⁺ T lymphocyte ratio and expression levels of IFN-γ andIL-12 in S. Typhimurium-challenged pigs. Therefore, the BBM could be agood candidate as an alternative antibiotic that improves Th 1-specific immune responsesand the bacterial clearance effect.     

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.     

Detection of mutations in the gyrA gene and class I integron from quinolone-resistant Salmonella enterica serovar Choleraesuis isolates in Taiwan

The quinolone resistance-determining regions (QRDRs) of the gyrA gene of quinolone-resistant Salmonella enterica serovar Choleraesuis isolates were sequenced. Four types of point mutation, Ser-83-to-Phe (TCC→TTC), Ser-83-to-Tyr (TCC→TAC), Asp-87-to-Gly (GAC→GGC), and Asp-87-to-Asn (GAC→AAC), were found. PCR-RFLP and MAS-touch down PCR were performed on fifty swine clinical isolates of S. enterica serovar Choleraesuis (Nal^R) collected during 1997–2002. The analysis indicated seven isolates with point mutations in codon 83, 13 with point mutations in codon 87, and 30 with double mutations in both codons 83 and 87. The MICs of enrofloxacin of the isolates with a single mutation in codon 83 or 87 were <2 μg/ml, while the MICs of the isolates with double mutations in both codon 83 and 87 ranged from 2 to 64 μg/ml. A class I integron comprised of dhfr, orfF and aad2 was also identified in both human and swine S. enterica serovar Choleraesuis isolates. These results indicate that PCR-RFLP and MAS-touchdown PCR assays can be used for surveillance of gyrA gene mutations, which are important for fluoroquinolone resistance in Salmonella. Isolates with double mutations in gyrA codons 83 and 87 are the major type of quinolone-resistant Salmonella isolated from swine in Taiwan. A surveillance system may be applied to the swine industry to monitor the emergence of fluoroquinolone and/or multi-drug-resistant S. enterica serovar Choleraesuis in Taiwan.     

Mutations in the Salmonella enterica serovar Choleraesuis cAMP-receptor protein gene lead to functional defects in the SPI-1 Type III secretion system

Salmonella enterica serovar Choleraesuis (Salmonella Choleraesuis) causes a lethal systemic infection (salmonellosis) in swine. Live attenuated Salmonella Choleraesuis vaccines are effective in preventing the disease, and isolates of Salmonella Choleraesuis with mutations in the cAMP-receptor protein (CRP) gene (Salmonella Choleraesuis ∆crp) are the most widely used, although the basis of the attenuation remains unclear. The objective of this study was to determine if the attenuated phenotype of Salmonella Choleraesuis ∆crp was due to alterations in susceptibility to gastrointestinal factors such as pH and bile salts, ability to colonize or invade the intestine, or cytotoxicity for macrophages. Compared with the parental strain, the survival rate of Salmonella Choleraesuis ∆crp at low pH or in the presence of bile salts was higher, while the ability of the mutant to invade intestinal epithelia was significantly decreased. In examining the role of CRP on the secretory function of the Salmonella pathogenicity island 1 (SPI-1) encoded type III secretion system (T3SS), it was shown that Salmonella Choleraesuis ∆crp was unable to secrete the SPI-1 T3SS effector proteins, SopB and SipB, which play a role in Salmonella intestinal invasiveness and macrophage cytotoxicity, respectively. In addition, caspase-1 dependent cytotoxicity for macrophages was significantly reduced in Salmonella Choleraesuis ∆crp. Collectively, this study demonstrates that the CRP affects the secretory function of SPI-1 T3SS and the resulting ability to invade the host intestinal epithelium, which is a critical element in the pathogenesis of Salmonella Choleraesuis.     

Multiple genetic typing of Salmonella Enteritidis phage-types 4, 6, 7, 8 and 13a isolates from animals and humans in the UK

Salmonella enterica serovar Enteritidis is a common cause of salmonellosis in people in the UK. This study aimed to assess the degree of genetic diversity among animal and human isolates from UK, Wales and northern Ireland. A total of 250 isolates from humans (n=59) and animals or their environment (n=191), belonging to the most common phage-types, were fingerprinted by a combination of PFGE, PS ribotyping and plasmid profiling. The different techniques identified different degrees of polymorphism (PS ribotyping (52 types)>PFGE (22 types)>plasmid profiling (17 types)). A prevalent genomic clone, as well as a variety of less frequent clones are present for each of the phage-types. In most cases, the prevalent clones appeared within isolates from several animal species and from several geographical locations. The percentage of sporadic clones found in animal and human populations were very similar. There was not clear evidence of a higher degree of diversity for human or animal isolates. Some clones were found to be present in both human and animal.     

上海市肉鸽沙门氏菌的分离鉴定及流行血清型和耐药性分析

为了解上海市农贸市场肉鸽群体中沙门氏菌流行血清型和耐药情况,本试验于2011-2014年间从上海市各区农贸市场采集肉鸽新鲜粪便样本92份,用XLD平板和沙门氏菌属显色培养基分离疑似沙门氏菌,革兰氏染色镜检并进行生化试验,共获得沙门氏菌24株,分离率为26.1%。采用Kauffmann-White法和K-B纸片法对24株沙门氏菌进行血清型鉴定和16种抗生素的药敏试验。血清型鉴定显示,24株沙门氏菌可分为鼠伤寒（66.7%）、阿贡纳（25.0%）和科瓦利斯（8.3%）3种血清型。药敏试验结果显示,有75.0%（18株）的分离株表现出不同程度耐药,其中分离株对四环素和磺胺异唑耐药率最高,均达到62.5%,其次为链霉素（58.3%）、萘啶酸（50.0%）、氨苄西林（20.8%）。多重耐药菌株15株（62.5%）,耐4种抗菌药物的菌株最多,占16.7%（7株）。另外,分离菌株对头孢吡肟、头孢噻肟、头孢噻甲羧肟、亚胺培南、氧氟沙星等5种药物的敏感率为100.0%,对奥格门丁和环丙沙星有12.5%的中介敏感率。本研究结果表明,上海市肉鸽中沙门氏菌的携带率较高,且菌株多重耐药现象较严重,这为食品中沙门氏菌的防控工作带来较大的挑战和风险,肉鸽沙门氏菌的流行和耐药情况应值得密切关注。     

Isolation,Identification and Analysis of Serotype and Drug Resistance of Salmonella from Pigeon in Shanghai

The purpose of this study was to investigate the molecular types and antimicrobial resistance of Salmonella isolated from pigeon in Shanghai from 2011 to 2014. A total of 92 fecal samples were collected from markets. XLD plate and Salmonella chromogenic medium were used to isolate suspected Salmonella colonies, and then determined the number of Salmonella through gram staining and biochemical tests. Among them, 24(26.1%) were positive for Salmonella. Kauffmann-White method and the K-B method were used respectively for serotype identification and susceptibility testing. In result, serological identification showed that 24 isolates from pigeon could be divided into 3 serotypes including S.typhimurium (66.7%), S.agona (25.0%) and S.corvallis (8.3%). Drug susceptibility test showed that 75.0% of the isolates were resistant to one antibiotic at least. The highest level resistance were found for tetracycline as well as sulfisoxazole (62.5%), followed by streptomycin (58.3%), nalidixic acid (50.0%) and ampicillin (20.8%). Multi-drug resistant strains accounted for 62.5% (15), in which the largest number of strains (7, 16.7%) were resistant to four drugs. In addition, isolates were 100.0% susceptible to cefepime, cefotaxime, ceftazidime, imipenem and ofloxacin, but 12.5% were moderately sensitive to the amoxicillin/clavulanic acid and ciprofloxacin. The study showed that Salmonella had a high separation rate of pigeon in Shanghai farmers market and performed serious multidrug resistance, which would bring great challenges and risks to the prevention and control of Salmonella in food, so that the prevalence and drug resistance of Salmonella in pigeon deserved close attention.     

Acute toxoplasmosis in three wild arctic foxes (Alopex lagopus) from Svalbard; one with co-infections of Salmonella Enteritidis PT1 and Yersinia pseudotuberculosis serotype 2b

Acute disseminated toxoplasmosis was diagnosed in three wild arctic foxes (Alopex lagopus) that were found dead in the same locality on Svalbard (Norway). The animals included one adult female and two 4-months-old pups. The adult fox was severely jaundiced. Necropsy revealed multifocal, acute, necrotizing hepatitis, acute interstitial pneumonia, and scattered foci of brain gliosis, often associated with Toxoplasma tachyzoites. One pup also had Toxoplasma-associated meningitis. In addition, the latter animal was infected with Yersinia pseudotuberculosis serotype 2b and Salmonella Enteritidis phage type 1 (PT1), which may have contributed to the severity of the Toxoplasma infection in this animal. The diagnosis of toxoplasmosis was confirmed by positive immunohistochemistry and detection of anti-Toxoplasma gondii antibodies in serum of all foxes. The animals were negative for Neospora caninum, canine distemper virus, canine adenovirus, and rabies virus on immunolabelling of tissue sections and smears.     

Antibiotic resistance and molecular characterization of ophthalmic Staphylococcus pseudintermedius isolates from dogs

The prevalence, virulence potential, and antibiotic resistance of ophthalmic Staphylococcus pseudintermedius (SP) isolated from dogs were examined. Sixty-seven Staphylococcus species were isolated from ophthalmic samples and surveyed for species-specific sequences in the Staphylococcus intermedius group (SIG) nuclease gene (SInuc), exfoliative toxin gene for SIG (siet), and antibiotic resistance genes (blaZ and mecA). PCR-restriction fragment length polymorphism analysis of the pta gene was also performed. Fifty isolates were identified as SIG strains, all of which were found to be SP. The blaZ gene was detected in 42 of the 50 SP strains and mecA gene was observed in 18 of the 50 SP strains. The 50 SP strains were most susceptible to amoxicillin/clavulanic acid (94%) and chlorampenicol (70%), and highly resistant to tetracycline (94%) and penicillin (92%). It was also found that 16 (88.9%) mecA-positive SP strains were resistant to oxacillin, tetracycline and penicillin. All mecA-positive SP were resistant to more than four of the eight tested antibiotics and therefore considered SP with multi-drug resistance (MDR). Our results indicate a high prevalence of antibiotic resistance genes in ophthalmic SP along with a close relationship between MDR SP strains and the mecA gene. Based on our findings, judicious administration of antibiotics to companion dogs is necessary.     

Prevalence and antibiotic resistance profiles ofSalmonella serotypes isolated from backyard poultry flocks in West Bengal,India

The present study was conducted to determine prevalence, virulence gene profile, serotyping, and antibiotic resistance patterns ofSalmonella in birds kept under the backyard system in West Bengal, India. The study also incorporated the detection ofSalmonella prevalence in their environment, including feed, drinking water, utensils, litter, dried manure under the house, soil, and eggs, which helped to formulate a biosecurity strategy. The study was conducted in 4 agro-climatic zones, such as the terai, new alluvial, red laterite, and coastal. Out of 360 samples, 22Salmonella isolates (6.1%) were identified.Salmonella were isolated from cloacal swabs of 6 birds (15%, n = 40), from 4 feed samples (10%, n = 40), 8 drinking water samples (20%, n = 40), and 4 eggs (10%, n = 40). Similar antigenic structure, nucleotide sequence (invA) ofSalmonella Enteritidis and Typhimurium, and randomly amplified polymorphic DNA banding patterns ofSalmonella Enteritidis were observed. It seems that the sameSalmonella isolate was present in feed sample, cloacal swabs, and eggs in the terai zone, whereas, it was found in drinking water, birds, and eggs in the new alluvial and in drinking water and birds in the coastal zone. A zone-specific biosecurity strategy was formulated based on the findings. The isolates were found to be resistant to chloramphenicol, ciprofloxacin, gentamicin, levofloxacin, norfloxacin, and oxytetracycline. None of the isolates possessed genes for major extended spectrum β-lactamases. Thus, the present study identified the source ofSalmonella contamination in the backyard chickens and their eggs in India with possible forms of biosecurity strategies. Our study was the first attempt in India to determine the prevalence, virulence gene profile, serotyping, and antibiotic resistance pattern ofSalmonella in backyard birds, including the environment and product.     

鸡肉源与病鸡源沙门菌血清型及耐药状况的比较

为了解市售鲜鸡肉中污染的与临床病鸡感染的沙门菌在血清型与耐药性的差异,对2012-2014年间自南宁市售鲜生鸡肉和同期送检病鸡中分离到的沙门菌进行了血清型分析以及耐药性的比较。结果显示,32株鸡肉源性沙门菌的血清型分布广泛,包括有德比、纽兰和阿贡纳沙门菌等16种血清型;39株病鸡源性沙门菌的血清型则较为单一,只有鸡白痢、鼠伤寒和鸡伤寒沙门菌3种血清型;两种来源的沙门菌均对四环素、复方新诺明、甲氧苄啶,氨苄西林及阿莫西林有较高的耐药性;另外,病鸡源性分离株中多重耐药菌株的比例(89.7%)比鸡肉源性的(56.2%)高。本研究表明,南宁市售鲜生鸡肉与病鸡中的沙门菌分离株在血清型来源上完全不同,提示市售鸡肉中污染的食源性沙门菌并非来自饲养阶段的患病鸡;病鸡源性沙门菌的耐药情况较鸡肉源性沙门菌的更为严重。     

Isolation,Identification and Analysis of Serotype and Antibiotic Susceptibility of Pathogenic Salmonella from Chickens

To investigate the situations of predominant strain and antibiotic resistance of pathogenic Salmonella from chickens in Guangxi Zhuang Autonomous region, Salmonella was pre-enriched and isolated from tissues of clinical suspected chickens, and the Salmonella isolates were identified by biochemical test using ID 32E System for the identification of Enterobacteriaceae of VITEK System ATB Expression, serotypes were determined by slid agglutination test, antibiotic susceptibility was analyzed by ATB VET Susceptibility Test Strip of Enterobacteriaceae antibiotics.The results showed that 34 Salmonella strains were obtained from 310 clinical samples, of which 1 strain belonged to A serogroup, 1 to C2 serogroup, 15 to B serogroup, 14 to D serogroup and 3 to untyped serogroup, and S.typhimurium of B serogroup and S.pullorum of D serogroup were the predominant serotypes.All Salmonella isolates were sensitive to meropenem, imipenem, spectinomycine and apramycine, and the resistance rates to chloramphenicol, kanamycine and gentamicine were less than 10%, and the resistance rates to amoxicillin, streptomycine, flumequine, oxolinique, sulfamethizol, tetracycline and nitrofurantoine ranged between 50% and 90%, while the resistance rates to penicilline, oxacilline, fusidique, rifampicine and metronidazole reached to 100%.The results indicated that the serotype distribution of pathogenic Salmonella from chickens exhibited regional characteristics, and S.typhimurium and S.pullorum were the predominant serotypes in Guangxi Zhuang Autonomous region, and antibiotic resistance of Salmonella isolates was very serious which should be highly concerned.