Salmonella species and serotypes isolated from farm animals, animal feed, sewage, and sludge in Saudi Arabia

A total of 264 salmonellae representing 65 different species and serotypes were isolated for the first time in Saudi Arabia, from various animal species, animal feed, sewage, and sludge. The six most frequently isolated Salmonella species or serotypes were: livingstone, concord, “S. schottmuelleri” (invalid), lille, S. typhimurium, and cerro.     

Characterization of multi-drug resistance in Salmonella strains isolated from animals

Spread of antibiotic resistances through agro-food chain remains an actual question for both researchers and public health operators. Our study investigates antimicrobial resistance in Salmonella spp. strains isolated from avicultural and swine samples (prevalence: 2% and 5.5% respectively). Strains belonging to different serotypes-pulsetypes have resulted multi-resistant in 76% of cases (avicultural strains: 13/23, swine strains: 73/90). Multi-drug resistant strains (MDR) have been studied for transferability by conjugation - observed in 25.6% cases - and for genetic determinants of resistances: 73.3% MDR strains harbour plasmids; class-1 integrons have been identified in 14 strains. Comparing our findings to available scientific literature, we discuss Salmonellosis resistance pattern according to the food chain and serotype.     

Phylogenetic relationship and genomic characterization of Salmonella Typhimurium strains isolated from swine in Brazil

Salmonella Typhimurium has been transmitted between humans and animals. Although, Brazil has been one of the largest pork meat exporters worldwide, there are few studies that characterized epidemiologically S. Typhimurium strains from swine. The aims of this work were to study the phylogenetic relationship of S. Typhimurium genomes isolated from swine in Brazil among themselves and with other genomes isolated from several sources and countries using wgMLST and cgMLST and to perform the search of Salmonella pathogenicity islands (SPIs). In addition, for S. Typhimurium strains from swine to compare the virulence and antimicrobial resistance genes by VFDB and ResFinder, genetic content by BLAST Atlas and orthologous proteins clusters by OrthoVenn. The constructed phylogenetic trees by wgMLST and cgMLST grouped the majority (92.3% and 80.7%, respectively) of the strains isolated from swine in Brazil into the same group. All the isolates contained important SPIs (SPI-1, SPI-2, SPI-3, SPI-5 and SPI-9). A total of 100 and 31 virulence and resistance genes were detected in the S. Typhimurium strains isolated from swine, respectively. The BLAST Atlas and orthologous proteins analysis found regions of phages and differences in metabolic, regulatory and cellular processes among S. Typhimurium LT2 and S. Typhimurium isolates from swine. In conclusion, molecular typing based in the wgMLST and cgMLST suggested that the S. Typhimurium isolates from swine studied were genetically related. The pathogenic potential of the strains studied was corroborated by the presence of important SPIs and virulence genes. The high number of antimicrobial resistance genes detected is worrying and reinforced their potential risk in swine in Brazil. The comparison by BLAST Atlas suggested differences in mobile genetic elements among S. Typhimurium LT2 and S. Typhimurium isolates from swine in Brazil. The orthologous proteins analysis revealed unique genes related to important cellular processes in the strains from swine.     

Characterization of multidrug-resistant Salmonella enterica serovar Heidelberg isolated from humans and animals

Salmonella enterica serovar Heidelberg has been recognized as one of the most common serovar associated with foodborne infections in the United States. It is also frequently isolated from nonhuman sources and has increasingly shown resistance to various antimicrobial agents. The present study was undertaken to identify the predominant antimicrobial resistance phenotypes and genotypes of Salmonella Heidelberg (n = 95) isolates of human, swine, and turkey origin. Antimicrobial susceptibility was done using Kirby-Bauer disk diffusion method with a panel of 12 antimicrobials. Pulsed-field gel electrophoresis genotyping was used to determine the diversity of the isolates. The antimicrobial resistance genes and carriage of Class 1 and 2 integrons were determined by polymerase chain reaction. All Salmonella Heidelberg isolates from swine were resistant to one or more of the antimicrobials tested and the majority (73.3%) showed multidrug resistance to streptomycin, tetracycline, and kanamycin (R-type: StTeKm). About 80% of the Salmonella Heidelberg isolates of human origin were pan-susceptible, however, one isolate showed multidrug resistance to 10 of 12 antimicrobials tested. Among the multidrug-resistant (MDR) Salmonella Heidelberg isolates, Class 1 integrons with variable sizes of 1.2 to 1.5 kb were detected in six isolates (three each) from humans and swine. DNA sequencing revealed that Class 1 integrons of both human and swine origin carried a gene encoding aminoglycoside adenyltransferase (aadA). Resistance genes identified in other loci include aphA1-Iab, strA, bla(TEM), and tetA (B). Both human and swine MDR strains of Salmonella Heidelberg carried the resistance phenotypes on self-transferable plasmids. Dendrogram analysis of pulsotypes indicated possible clonality of Salmonella Heidelberg between isolates of human and swine origin. The findings in this study indicate the increasing significance of swine as reservoirs of emerging MDR serovars, such as MDR Salmonella Heidelberg, is of public health significance.     

2008-2009年北京市沙门菌流行特征和分子分型

目的 分析2008-2009年北京市沙门菌流行特征及脉冲场凝胶电泳(PFGE)分子分型. 方法 对2008-2009年通过WHO全球沙门菌监测系统及北京市肠道门诊监测系统分离到的137株沙门菌进行生化鉴定、血清分型和相关流行病学分析;利用PFGE进行分子分型. 结果 北京市2008-2009年沙门菌的流行具有明显季节性,6-9月份高发,共分离菌株84株,占64.1%(84/131);患者年龄多为18～40岁,占46.1%(58/128);男性80例,女性51例,男女比例为1.57:1.137株沙门菌分属于20种血清型,其中肠炎沙门菌和鼠伤寒沙门菌为优势菌型,分别占46.7%(64/137)和17.5%(24/137).共分71种PFGE带型,其中肠炎沙门菌和鼠伤寒沙门菌都有16种PFGE型别.肠炎沙门菌的4种PFGE型别(JEGX01.CN0001、JEGX01.CN0003、JFGX01.CN0002、JEGX01.CN0019)和鼠伤寒沙门菌的JPXX01.CN0001为优势分子型别. 结论 2008-2009年北京市沙门菌的流行具有性别、年龄和季节性分布特征;PFGE分子型别较多,且存在差异明显的多个克隆系.

Abstract：

Objective To study the epidemiological characteristics and molecular phenotypes of Salmonella by pulsed-field gel electrophoresis (PFGE) in Beijing from 2008 to 2009. Methods A total of one hundred thirty-seven isolates recovered from the WHO Global Samonella Surveillance system and entero clinic surveillance system were identified by biochemical tests and serotyping.The related epidemiological informations were also analyzed.The isolates were further typed by PFGE. Results The prevalence of Salmonella from 2008 to 2009 showed obvious seasonal character.High incidence occurred from June to September,and 64.1% (84/131) isolates were recovered in this period.Patients of 18-40 year-old were 46.1% (58/128) and 80 patients were male and 40 patients were female with the ratio of 1.57:1.These 137 Salmonella isolates belonged to 20 serotypes,including Enteritidis (46.7%,64/137) and Typhimurium (17.5%,24/137) as the dominant serotype.In total,71 PFGE profiles were identified.Four PFGE patterns of S.Enteritidis isolates (JEGX01.CN0001,JEGX01.CN0003,JEGXO1.CN0002,JEGX01.CN0019) and S.Typhimurium pattern of JPXX01.CN0001 were dominant patterns. Conclusion The prevalence of Salmonella from 2008 to 2009 showed distribution characteristics of sex,age and seasons.The numerous PFGE patterns of Salmonella showed diversity of these isolates and different clones existed in Beijing.     

上海市鼠伤寒沙门菌流行特征及分子分型研究

[目的]研究上海市2006—2007年鼠伤寒沙门菌腹泻病例株的分子流行病学特征。[方法]追溯2002—2007年食品中分离的鼠伤寒沙门菌来源,比较鼠伤寒沙门菌食源株与腹泻株的抗生素耐药性;对全球沙门菌监测(GSS)病例和食品中分离的鼠伤寒沙门菌进行血清、耐药表型和脉冲凝胶电泳(PFGE)分子分型。[结果]经培养确认的鼠伤寒沙门菌腹泻病例数,在2006—2007年本市非伤寒沙门菌型病例构成中仅次于肠炎沙门菌,食品菌株多源于禽(64.4%)和畜肉制品(17.8%),其多重耐药菌株显著高于腹泻株(P0.05)。PFGE将7株食品株和44株腹泻株分为23种带型,优势型为1型(8株)、2型(6株)、29型(4株)、49型(8株)和6型(4株),与食源菌株完全匹配的仅有49型、6型共7个病例(15.9%,7/44)。PFGE-1型腹泻株在2006和2007年分别为2例和6例,2型分别为4例和2例。[结论]上海市鼠伤寒沙门菌腹泻病例存在高度散发和分散爆发的流行特征,没有与本地食品菌株相匹配的优势克隆型分别是PFGE 2型和1型,与市售生鲜类肉食品污染株之间的遗传同源性低。推测传染源可能由输入性传染源对食品等媒介形成二次污染所致。建议加强流行病学调查,以揭示潜在的传染源和传播途径。     

Antibiotic resistance in Salmonella enterica serotypes Typhimurium, Enteritidis and Infantis from human infections, foodstuffs and farm animals in Italy

The antimicrobial susceptibility of isolates of Salmonella enterica serotypes Typhimurium, Enteritidis, and Infantis isolated from humans, foodstuffs and farm animals in Italy between 1999 and 2001 was examined. All the isolates were susceptible to cefotaxime and ciprofloxacin, but high rates of resistance were observed for several other drugs, especially for S. Typhimurium. The rates of resistance and multiresistance were generally higher among animal and food isolates than in human strains; conversely, no significant difference was observed between animal and food isolates. Among S. Typhimurium, multiresistance was more common in bovine, poultry and rabbit strains than in swine isolates, and was rare in strains from pigeon. Resistance to trimethoprim sulphamethoxazole was mainly found in isolates of swine and human origin. This study confirms the role of livestock as a reservoir of drug-resistant Salmonella spp. and underlines the need for integrated surveillance systems of antibiotic resistance that consider isolates not only from human disease but also from the animal reservoirs and the food vehicles.     

Salmonella isolated from humans,animals and other sources in Canada, 1983-92.

A total of 89760 human and 22551 non-human isolates of salmonella were serotyped in Canada during the period 1983-92. There were 2180 reported outbreaks associated with 10065 cases during the 10-year period. The most common salmonella serovars isolated from human and non-human sources were S. typhimurium and S. hadar. The third and fourth most common serovars from human sources were S. enteritidis and S. heidelberg, respectively, and from non-human sources they were S. heidelberg and S. infantis. The number of S. typhimurium isolations from human and non-human sources showed a downward trend over the 10-year period. A total of 222 outbreaks of S. typhimurium associated with 1622 cases occurred. The S. hadar isolations from human and non-human sources reached a peak during the years 1987-90 and declined thereafter. The number of human isolates of S. enteritidis increased until 1985 and fluctuated at a level of 8.3-12.8% of all human isolates thereafter. Seventy-three outbreaks of S. enteritidis infection associated with 568 cases occurred. More than 50% of the S. enteritidis infections in humans were caused by phage type (PT) 8. During the review period, infections caused by PT4 were less common and were almost exclusively found in people who had travelled abroad. The annual isolation rates of S. heidelberg from human and non-human sources increased steadily during the period. Bacteriophage typing of serovars from outbreaks showed that contaminated food products of poultry and bovine origin were common sources of human infection. Salmonella typhi was identified as the cause of 43 small outbreaks affecting 116 persons.     

IS200 fingerprint of Salmonella enterica serotype Typhimurium human strains isolated in Sardinia.

A collection of Salmonella enterica serotype Typhimurium human strains isolated in Northern Sardinia (Italy) was examined for the insertion sequence IS200, phage type, antibiotic profile, ribotyping polymorphisms and plasmid profile. All clinical isolates studied contained from 4 to 10 copies of the IS200 element. IS200 permitted to discriminate Typhimurium strains and to identify five IS200 types, some of them circulating in Sardinia at least since 1900. Strains belonging to phage DT104 predominated and correlated with a specific IS200 pattern.     

Prevalence and mechanisms of quinolone resistance among selected nontyphoid Salmonella isolated from food animals and humans in Korea

The aim of this study was to investigate the prevalence and mechanism of quinolone resistance among selected nontyphoid Salmonella (NTS) isolates. A total of 1279 NTS isolated from food animals (n=692) and humans (n=587) between 1995 and 2009 were investigated by serotyping, antimicrobial susceptibility testing, screening for plasmid-mediated quinolone resistance (PMQR) genes qnr, aac(6')-Ib-cr, and qepA and mutations in the quinolone resistance-determining region (QRDR) of gyrA and parC by PCR, and DNA sequencing. Three hundred thirty (47.7%) of 692 animal isolates and 177 (30.2%) of 587 human isolates were resistant to nalidixic acid. Most animal (94.8%, 313/330) and human (99.4%, 176/177) NTS exhibited decreased ciprofloxacin susceptibility (minimum inhibitory concentration [MIC]: 0.125-2?mg/L). None of them carried qnr or qepA gene. However, aac(6')-Ib was identified in six animal isolates, of which four carried aac(6')-Ib-cr gene. Based on antimicrobial resistance profile, year of isolation, MIC for quinolones and fluoroquinolones, and isolation frequency of serotype, 114 animal and 83 human isolates were tested for QRDR mutations. All contained a single mutation within the QRDR of gyrA at either codon 87 or 83, and 41 of them contained an additional mutation in parC. The most prevalent mutation was Asp87-Tyr (n=107), followed by Asp87-Gly (n=28), Asp87-Asn (n=26), Ser83-Tyr (n=22), and Ser83-Phe (n=14). Point mutations in parC were observed outside the QRDR, which included 40 isolates with Thr57-Ser substitution and 1 Salmonella Typhimurium with a novel Glu51-Lys substitution. In conclusion, a point mutation within the QRDR of gyrA was primarily responsible for quinolone resistance and reduced susceptibility to fluoroquinolones in NTS in Korea. To our knowledge, this is the first report of occurrence of aac(6')-Ib-cr gene among NTS in Korea. The spread of NTS carrying aac(6')-Ib-cr is of serious concern and should be carefully monitored.     

Characteristics of strains of Salmonella enterica serovar Typhimurium DT104 isolated in the Slovak Republic

From 1997 to 2000 in the Slovak Republic 8 strains of Salmonella enterica serovar Typhimurium DT104 were isolated from sporadic cases of human salmonellosis. Four strains were multiresistant and three strains were sensitive to antibiotics. We investigated the influence of the cultivation medium (complete Müeller-Hinton, synthetic-Staples) on growth, surface hydrophobicity and motility of the mentioned isolates. The hydrophobicity was evaluated by methods of adherence to the hydrocarbon xylene (BATH) in a salt-aggregation test with ammonium sulphate (SAT) and adherence to a plast. The growth of tested strains in 24 hours was greater after cultivation in the complete medium, but the salmonellae grew considerably also in the synthetic medium where the only source of C and N was asparagine. Of the investigated characteristics the cultivation medium influenced most the adherence of isolates to xylene as after cultivation in a synthetic medium all isolates with the exception of two were hydrophobic. The motility of strains was also greater after growth in this medium. Conversely cultivation in complete medium suppressed these properties of isolates. The cultivation medium did not influence the adherence of isolates to plasts and only a slight influence was observed on the salt aggregating properties of the investigated strains.     

Multidrug-resistant Salmonella Typhimurium infection from milk contaminated after pasteurization

An outbreak of multidrug-resistant Salmonella enterica serotype Typhimurium infections occurred in Pennsylvania and New Jersey. A case-control study implicated pasteurized milk from a dairy, and an inspection indicated the potential for contamination after pasteurization. Dairy cattle are the likely reservoir, and milk may be an important vehicle of Salmonella transmission to humans.     

2011-2017年济南市呼吸道腺病毒流行特征及其基因分型

目的监测2011-2017年山东济南急性呼吸道感染(acute low respiratory tract infection,ALRTI)中腺病毒(Human Adenovirus, HAd V)的感染情况,揭示济南地区不同年份、不同季节腺病毒感染的流行病学特征和基因进化树特点。方法2011-2017年在济南市中心医院、山东大学齐鲁儿童医院共采集1 730份急性呼吸道感染住院病例鼻、咽拭子标本,采用荧光定量PCR方法对标本进行腺病毒检测。检测为腺病毒阳性的标本再进行病毒分离、PCR扩增、Hexon测序、Blast比对,构建基因进化树,确定腺病毒型别,分析其进化特点。结果在收集的1 730份标本中,共102份确定为腺病毒核酸阳性,阳性率为5.90%,其中2011年阳性率最高,为14.78%,2012年阳性率最低,为2.34%;阳性率最高的为1月份,达到10.33%,最低的为8月份,为1.91%;阳性率最高的为5～15岁年龄组,为9.76%,最低的为≥60岁年龄组,为1.37%。从102份腺病毒核酸阳性标本中分离出50株腺病毒,分子分型共检出5个血清型,其中最多的为3型,占54%,其次为...     

Experimental airborne transmission of Salmonella Agona and Salmonella Typhimurium in weaned pigs

This study tested the hypothesis of airborne transmission of Salmonella Agona (Trial I) and Salmonella Typhimurium (Trial II) in weaned pigs. The trials were performed using stainless-steel/glass isolation cabinets connected by air ducts to permit an unidirectional airflow from cabinet 1 (two control pigs) to cabinet 3 (two sentinel pigs), passing through cabinet 2 (two inoculated pigs). Air samples, pooled faecal samples from the floor and rectal swabs were collected daily and assessed by culture and PCR. A fumigation chamber and rubber gloves coupled to the cabinets allowed sampling without opening the system. Trials I and II lasted 15 and 19 days respectively. The recovery of S. Agona and S. Typhimurium and detection of seroconversion in sentinel pigs indicate that airborne Salmonella transmission in weaned pigs over short distances is possible. Further studies on the role of aerosols in the epidemiology of Salmonella in intensive pig production should be performed.     

Multiresistant Salmonella Typhimurium DT104 infections of humans and domestic animals in the Pacific Northwest of the United States

Salmonella Typhimurium definitive type 104 with chromosomally encoded resistance to five or more antimicrobial drugs (R-type ACSSuT+) has been reported increasingly frequently as the cause of human and animal salmonellosis since 1990. Among animal isolates from the northwestern United States (NWUS), R-type ACSSuT+ Typhimurium isolates increased through the early 1990s to comprise 73% of Typhimurium isolates by 1995, but subsequently decreased to comprise only 30% of isolates during 1998. NWUS S. Typhimurium R-type ACSSuT+ were consistently (99%) phage typed as DT104 or the closely related DTu302. S. Typhimurium isolates from cattle with primary salmonellosis, randomly selected from a national repository, from NWUS were more likely to exhibit R-type ACSSuT+ (19/24, 79%) compared to isolates from other quadrants (17/71, 24%; P < 0.01). Human patients infected with R-type ACSSuT+ resided in postal zip code polygons of above average cattle farm density (P < 0.05), while patients infected with other R-types showed no similar tendency. Furthermore, humans infected with R-type ACSSuT+ Typhimurium were more likely to report direct contact with livestock (P < 0.01) than humans infected with other R-types.     

Salmonella serovars defined in Poland

One hundred and sixty nine serovars of Salmonella, belonging to 28 different O groups, were defined in the National Salmonella Centre. All the serovars were isolated in Poland. Above 70% (121/169) of them belonged to five O groups--O:4 (31 serovars), O:7 (28 serovars), O:8 (27 serovars), O:3,10 (20 serovars) and O:9 (15 serovars). Other O groups were represented by some (1 to 8) serovars. All the serovars were described according to the changes in taxonomy of the genus Salmonella and in serovars nomenclature. These changes, proposed by WHO Collaborating Centre for Reference and Research on Salmonella (Paris, France), reflect the recent advances in Salmonella taxonomy.     

Salmonella enterica serotype Typhimurium DT104 isolated from humans, United States, 1985, 1990, and 1995

First isolated from an ill person in 1985, multidrug-resistant Salmonella enterica serotype Typhimurium DT104 emerged in the mid-1990s as a strain of Salmonella frequently isolated from humans in the United States. We compared the integron content, plasmid profile, and XbaI pulsed-field gel electrophoresis (PFGE) patterns of multidrug-resistant S. Typhimurium DT104 (MR-DT104) isolated from humans in the United States in 1985, 1990, and 1995. All isolates contained a 60-mDa plasmid and had indistinguishable PFGE and integron profiles, supporting the idea of a clonal relationship between recent and historical isolates. The data suggest that the widespread emergence of MR-DT104 in humans and animals in the 1990s may have been due to the dissemination of a strain already present in the United States rather than the introduction of a new strain.