Genetic typing of human and food isolates of Listeria monocytogenes from episodes of listeriosis

Ten clinical and food Listeria monocytogenes strains isolated during the epidemiological investigations of episodes of listeriosis (one outbreak and two sporadic cases) that occurred in northern Italy during 1993–1995 have been examined by DNA macrorestriction pattern analysis obtained by PFGE and RAPD typing, in order to confirm the food vehicle of infections. The same DNA profiles within the isolates from the three episodes were obtained by both techniques. The ApaI and SmaI PFGE profiles and RAPD patterns with primer OPM-01 confirmed the close relationship between strains from two distinct episodes. However, RAPD analysis with primer UBC-127 distinguished between these L. monocytogenes isolates.     

Multiple-locus variable number of tandem repeat analysis as a tool for molecular epidemiology of botulism: The Italian experience

Clostridium botulinum is the bacterial agent of botulism, a rare but severe neuro-paralytic disease. Because of its high impact, in Italy botulism is monitored by an ad hoc surveillance system. The National Reference Centre for Botulism, as part of this system, collects and analyzes all demographic, epidemiologic, microbiological, and molecular data recovered during cases and/or outbreaks occurred in Italy.A panel of 312 C. botulinum strains belonging to group I were submitted to MLVA sub-typing. Strains, isolated from clinical specimens, food and environmental samples collected during the surveillance activities, were representative of all forms of botulism from all Italian regions.Through clustering analysis isolates were grouped into 12 main clusters. No regional or temporal clustering was detected, demonstrating the high heterogeneity of strains circulating in Italy.This study confirmed that MLVA is capable of sub-typing C. botulinum strains. Moreover, MLVA is effective at tracing and tracking the source of contamination and is helpful for the surveillance system in terms of planning and upgrading of procedures, activities and data collection forms.     

Second generation subtyping: a proposed PulseNet protocol for multiple-locus variable-number tandem repeat analysis of Shiga toxin-producing Escherichia coli O157 (STEC O157)

Most bacterial genomes contain tandem duplications of short DNA sequences, termed "variable-number tandem repeats" (VNTR). A subtyping method targeting these repeats, multiple-locus VNTR analysis (MLVA), has emerged as a powerful tool for characterization of clonal organisms such as Shiga toxin-producing Escherichia coli O157 (STEC O157). We modified and optimized a recently published MLVA scheme targeting 29 polymorphic VNTR regions of STEC O157 to render it suitable for routine use by public health laboratories that participate in PulseNet, the national and international molecular subtyping network for foodborne disease surveillance. Nine VNTR loci were included in the final protocol. They were amplified in three PCR reactions, after which the PCR products were sized using capillary electrophoresis. Two hundred geographically diverse, sporadic and outbreak- related STEC O157 isolates were characterized by MLVA and the results were compared with data obtained by pulsed-field gel electrophoresis (PFGE) using XbaI macrorestriction of genomic DNA. A total of 139 unique XbaI PFGE patterns and 162 MLVA types were identified. A subset of 100 isolates characterized by both XbaI and BlnI macrorestriction had 62 unique PFGE and MLVA types. Although the clustering of isolates by the two subtyping systems was generally in agreement, some discrepancies were observed. Importantly, MLVA was able to discriminate among some epidemiologically unrelated isolates which were indistinguishable by PFGE. However, among strains from three of the eight outbreaks included in the study, two single locus MLVA variants and one double locus variant were detected among epidemiologically implicated isolates that were indistinguishable by PFGE. Conversely, in three other outbreaks, isolates that were indistinguishable by MLVA displayed multiple PFGE types. An additional more extensive multi-laboratory validation of the MLVA protocol is in progress in order to address critical issues such as establishing epidemiologically relevant interpretation guidelines for the MLVA data.     

Low genetic diversity and epidemiological significance of Listeria monocytogenes isolated from wild animals in the far east of Russia

The causative agent of listeriosis, a serious disease of humans and animals, Listeria monocytogenes is a ubiquitous bacterium that inhabits both anthropogenic and pristine environments. We report L. monocytogenes isolation from wild animals, humans, food and the environment of a far eastern region of Russia. In total, 654 samples of internal organs of small rodents belonging to the Muridae and Cricetidae families, and 986 samples of the liver and muscles of mollusks and fish were examined to obtain 7 and 14 independent L. monocytogenes isolates, respectively. The wild animal isolates were compared with human (n=9), food (n=8) and environmental (n=3) isolates obtained in the same region. Twenty of the 21 wild animal isolates belonged to the serovar 4b. The serovars 4b, 1/2a, 1/2b, and 4b, 1/2a, 1/2b, 1/2c were found between human and food isolates, respectively. All isolates were characterized into molecular subtypes by DNA sequencing of the 618 bp internal fragment of the house keeping gene prs and 621 bp internal fragment of the virulence gene inlB. Sequence analysis revealed 4 and 13 alleles for prs and inlB fragments, respectively. Distinct prs and inlB alleles clustered into two groups consistently with established phylogenetic lineages. Among isolates of every lineage, the nucleotide diversity of the prs fragment was low; the nucleotide diversity of the inlB fragment was low among wild animal isolates and higher among human isolates. All rodent isolates and 10 of 14 marine organism isolates carried the same allele of the inlB fragment, which was also found among environmental (two of three), food (two of eight) and human (two of nine) isolates.     

间隔区寡核苷酸分型和多位点可变数量串联重复序列分析在结核分枝杆菌基因分型中的应用

目的评价间隔区寡核苷酸分型(Spoligotyping)及多位点可变数量串联重复序列分析(MLVA)方法在结核分枝杆菌基因分型研究中的应用。方法收集224株结核分枝杆菌临床分离株,分别采用Spoligotyping及MLVA方法进行基因分型,比较两种方法的分型效果,评价两种方法在结核分枝杆菌基因分型中的应用。结果使用Spoligotyping方法,224株结核分枝杆菌呈现出55种基因型,39株具有独特的基因型,其余185株菌呈现出16种基因型;使用MLVA方法时,224株结核分枝杆菌呈现出160种基因型,132株具有独特的基因型,余下的92株菌呈现出28种基因型;当两种方法联合使用时,224株结核分枝杆菌呈现出179种基因型,159株结核分枝杆菌具有独特的基因型,余下的65株菌表现为20种基因型。湖南省和安徽省的菌株中北京家族菌株所占的比例差异有统计学意义(P<0.001),安徽省北京家族菌株所占的比例明显高于湖南省。结论MLVA在结核分枝杆菌株水平的鉴定方面,其分辨能力高于Spoligotyping,但是Spoligotyping在鉴定北京家族菌株和M.bovis方面有一定的优势。将Spoligotyping方法作为一线分型技术,MLVA作为二线分型技术联合应用时,将提高结核病的流行病学调查和病原学监测效果。不同地区的菌株有不同的特点。     

陕西省布鲁氏菌分离株MLVA分型研究

目的 对陕西省1952—2019年以来保存的布鲁氏菌分离株进行MLVA分型研究,了解陕西省布鲁氏菌遗传变异情况,为制定预防控制策略提供依据。方法 基于MLVA技术对收集的121株布鲁氏菌分离株基因型进行研究,利用Bio Numerics 7.6软件进行聚类分析,计算辛普森指数。结果 基于MLVA-8分型,分为7种,即羊种菌5种（42、43、63、83及115型）,猪种菌1种（6型）及牛种菌1种（38型）,其中羊种42、43型占总数的91.74%;42型在全省10个市区均有分布;榆林、延安均有4种基因型,多样性较其他市区更丰富;基于MLVA-11,分为11种,基于MLVA-16对121株菌种进行聚类分析结果显示,所有菌株分为3个群,96个基因型,呈现基因型别的多样性,辛普森指数在0.000～0.800之间,Panel 1和Panel 2A多样性均明显低于Panel 2B。结论 MLVA技术可用于种属亲缘关系的确立、菌株遗传多样性分析以及分子流行病学溯源调查,陕西省布鲁氏菌MLVA分型显示高度基因多态性,提示陕西省布病流行呈零星和散发特征, 因此,降低传染源在区域之间的频繁流动,是控制布病疫情发生的有效手段。     

The characterization and comparison of Staphylococcus aureus by antibiotic susceptibility testing, enterobacterial repetitive intergenic consensus-polymerase chain reaction, and random amplified polymorphic DNA-polymerase chain reaction

Thirty-five of Staphylococcus aureus isolated from food raw materials and workers' hands in a noshery were characterized using antibiotic susceptibility testing, enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR), and random amplified polymorphic DNA (RAPD)-PCR. As a similarity threshold of 90%, ERIC-PCR classified 35 S. aureus isolates into 28 ERIC types with discrimination indexes (D) of 0.984, while RAPD-PCR grouped 35 S. aureus isolates into five clusters (A-E) showing 19 RAPD types with D of 0.949. Four resistance patterns were observed with D of 0.826. A comparison of characterization of S. aureus indicated a clear correlation between ERIC-PCR and RAPD-PCR or resistance patterns in some strains. It was concluded that ERIC-PCR method could be used for genetic diversity of S. aureus and tracing the sources of it from the food chain.     

Comparison of Listeria monocytogenes strain types in Irish smoked salmon and other foods

An investigation of Listeria monocytogenes in Irish retail smoked salmon products and other unrelated food products was undertaken. Serotyping and genotyping methods were applied. Twenty-six L. monocytogenes isolates cultured from ready-to-eat smoked salmon and an additional 20 L. monocytogenes isolates from various commercially available food products (other than smoked salmon) were compared. Four serotypes, 12 ribotypes, 12 amplified fragment length polymorphism (AFLP) types and 17 pulsed-field gel electrophoresis (PFGE) types were identified among the 46 isolates studied. Genotyping identified a single dominant strain that accounted for 65% of those cultured from smoked salmon and this strain was present in product obtained from three out of five of the manufacturers surveyed. When compared to the food products obtained from a variety of sources, those from smoked salmon appeared to cluster as a single group. In Irish smoked salmon this strain may have adapted, and be capable of persisting in this food product. All isolates were grouped into genetic lineages based on their EcoR1 ribotypes. The attendant risk to public health following consumption of these foods is discussed.     

A comparative study of clinical and food isolates of Listeria monocytogenes and related species

Ninety-six isolates of presumptive or confirmed Listeria monocytogenes were obtained from local clinical (30 isolates) or food laboratories (66 isolates). Minimal biochemical analysis identified only 80% of these isolates as L. monocytogenes the remaining included L. seeligeri, 1%, or the non-haemolytic L. innocua, 19%. The 27 clinical and 50 food isolates, mainly from meat products, frozen confectionaries, and cheeses, confirmed as L. monocytogenes were compared biochemically and serologically. Twenty-one isolates, including some strains of L. innocua and L. seeligeri, were examined for pathogenicity in immunocompromized mice and 44 typed using bacterial restriction endonuclease DNA analysis (BRENDA). Only isolates of L. monocytogenes were found to be pathogenic. Biovar-typing of the isolates was unreliable and provided poor discrimination. Serogroups 1/2 and 4 predominated among clinical and food isolates and BRENDA provided better discrimination among isolates. Ten stable and reproducible restriction patterns were observed among the Listeria sp. isolates studied. Overall, a combination of techniques gave the best discrimination and indicated their potential for use as epidemiological tools.     

肠炎沙门菌可变数目串联重复序列位点用于多位点可变数目串联重复序列分型分析的评价

目的 评价不同肠炎沙门菌可变数目串联重复序列(VNTR)位点用于多位点可变数目串联重复序列(MLVA)分型的可行性.方法 选取已报道使用的肠炎沙门菌11个VNTR位点,对中国不同时间和地区分离的16株菌进行初步评价,选取具有单一扩增条带的位点进行104株肠炎沙门茵的MLVA分型分析.对这些菌株同时进行脉冲场凝胶电泳(PFGE)分析,比较MLVA分型方法与PFGE分型方法对菌株分型能力的强弱.结果 初筛得到7个VNTR位点用于扩大菌株的分析,这些位点将104株菌分为16个MLVA型别,D值为0.7222,这些菌株同时被分为22个PFGE型别,D值为0.7974.对两种方法各自所分的最大组包含的菌株进行比较,发现PFGE具有更强的分辨能力;从频数分布看,PFGE方法分型结果比较分散,MLVA分型较为集中.结论 用于国际肠炎沙门菌分型具有扩增多态性的VNTR位点在国内分离株中并不都具有多态性结果,在MLVA方法学建立中应选择更多的VNTR位点进行广泛的筛选才有利于国际实验室间的方法的统一.     

Listeriosis associated with gorgonzola (Italian blue-veined cheese)

We describe a case of listeriosis in Italy associated with the consumption of cheese. Opened samples of two brands of gorgonzola (Italian blue-veined cheese; referred to as brands "B" and "C") were collected from the patient's refrigerator. Unopened samples of the brand suspected to be the source of infection (brand B) were taken from the store where the cheese had been purchased, other local stores, and the production plant. Listeria monocytogenes serotype 1/2b was isolated from the patient and from the opened and unopened cheese samples. The contamination level varied from <100 to 1,200 cfu g(-1). Molecular typing of the isolates, using both randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE), demonstrated that the isolates from the patient's refrigerator, food stores, and production-plant samples were indistinguishable from the clinical isolate. Molecular typing verified the peristence of closely related L. monocytogenes isolates in the production plant B for 5 months. The results stress the importance of developing a code of hygienic practice for preventing, limiting, and where possible, eliminating this pathogen in processed foods and of educating at-risk persons on foods likely to be contaminated.     

肠炎沙门菌可变数目串联重复序列位点用于多位点可变数目串联重复序列分型分析的评价

目的 评价不同肠炎沙门菌可变数目串联重复序列(VNTR)位点用于多位点可变数目串联重复序列(MLVA)分型的可行性.方法 选取已报道使用的肠炎沙门菌11个VNTR位点,对中国不同时间和地区分离的16株菌进行初步评价,选取具有单一扩增条带的位点进行104株肠炎沙门茵的MLVA分型分析.对这些菌株同时进行脉冲场凝胶电泳(PFGE)分析,比较MLVA分型方法与PFGE分型方法对菌株分型能力的强弱.结果 初筛得到7个VNTR位点用于扩大菌株的分析,这些位点将104株菌分为16个MLVA型别,D值为0.7222,这些菌株同时被分为22个PFGE型别,D值为0.7974.对两种方法各自所分的最大组包含的菌株进行比较,发现PFGE具有更强的分辨能力;从频数分布看,PFGE方法分型结果比较分散,MLVA分型较为集中.结论 用于国际肠炎沙门菌分型具有扩增多态性的VNTR位点在国内分离株中并不都具有多态性结果,在MLVA方法学建立中应选择更多的VNTR位点进行广泛的筛选才有利于国际实验室间的方法的统一.     

肠炎沙门菌可变数目串联重复序列位点用于多位点可变数目串联重复序列分型分析的评价

目的 评价不同肠炎沙门菌可变数目串联重复序列(VNTR)位点用于多位点可变数目串联重复序列(MLVA)分型的可行性.方法 选取已报道使用的肠炎沙门菌11个VNTR位点,对中国不同时间和地区分离的16株菌进行初步评价,选取具有单一扩增条带的位点进行104株肠炎沙门茵的MLVA分型分析.对这些菌株同时进行脉冲场凝胶电泳(PFGE)分析,比较MLVA分型方法与PFGE分型方法对菌株分型能力的强弱.结果 初筛得到7个VNTR位点用于扩大菌株的分析,这些位点将104株菌分为16个MLVA型别,D值为0.7222,这些菌株同时被分为22个PFGE型别,D值为0.7974.对两种方法各自所分的最大组包含的菌株进行比较,发现PFGE具有更强的分辨能力;从频数分布看,PFGE方法分型结果比较分散,MLVA分型较为集中.结论 用于国际肠炎沙门菌分型具有扩增多态性的VNTR位点在国内分离株中并不都具有多态性结果,在MLVA方法学建立中应选择更多的VNTR位点进行广泛的筛选才有利于国际实验室间的方法的统一.

Abstract：

Objective To evaluate the feasibility of the application of variable-number tandem repeat(VNTR)loci of Salmonella Enteritidis(S. enteritidis)in subtyping mutiple-locus variable-number tandem repeat analysis(MLVA).Methods A total of 16 isolates of S.enteritidis from different place and time in China were preliminarily assessed by choosing 11 reported VNTR loci.the loci with single amplified bands were picked to subtype all 104 S.enteritidis isolates.The isolates were also analyzed by pulse field gel electrophoresis(PFGE)to compare the superiority or inferiority of MLVA method and PFGE method.Results Seven VNTR loci were selected from the preliminary screening to expand the analysis,and the 7 VNTR loci had grouped 104 of S.enteritidis isolates into either 16 MLVA subtypes or 22 PFGE subtypes.with the D value at 0.7222 and 0.7974,respectively.Comparing with the isolates in MLVA subtypes.the isolates in PFGE showed a stronger resolving power.Meanwhile the results in PFGE showed a more disperse frequency distribution than those in MLVA.Conclusion These results indicate that some VNTR locus which have shown a good polymorphism intemationaUy,may fail to show polymorphism in China.thereby.more VNTR loci should be included in MLVA and the wide screening may benefit the unity of global laboratorial methods.     

Canadian listeriosis reference service

Listeria monocytogenes, a psychrotrophic organism capable of growing at refrigeration temperatures, is of major concern in extended shelf life, refrigerated foods. Considering that as much as 80-90% of human listeriosis cases are linked to the ingestion of contaminated food, human cases are predominantly seen in high-risk individuals, including organ-transplant recipients, patients with AIDS and HIV-infected individuals, pregnant women, cancer patients, and the elderly. In 2001, the Canadian Listeriosis Reference Service (LRS) was created by the Bureau of Microbial Hazards (Health Canada) and the National Microbiology Laboratory (now part of the Public Health Agency of Canada). Major goals of the LRS include investigation of listeriosis cases and maintenance of a national collection of isolates. The LRS intends to create a comprehensive molecular epidemiological database of all isolates in Canada for use as a resource for outbreak investigations, research and other microbiological investigations. The PFGE profiles are being established and stored for clinical, food, environmental, and possibly animal strains of L. monocytogenes. The LRS pursues research activities for investigation and implementation of other molecular methods for characterizing L. monocytogenes isolates. Ribotyping, Multi-locus Sequence Typing (MLST), Variable Number of Tandem Repeats (VNTR), Multi-locus virulence sequence typing (MLVA), microarray- based technologies and sequence-based typing schemes, are being investigated on selected diversity sets. The LRS has also used PFGE typing for outbreak investigations. The molecular epidemiological data, timely coordination and exchange of information should help to reduce the incidence of listeriosis in Canada. In Canada, listeriosis is not a national notifiable disease, except for the province of Quebec, where it has been since 1999. The LRS, Canadian Public Health Laboratory Network, and federal epidemiologists are currently working on making human listeriosis notifiable throughout Canada.     

Genetic characterization of non-O157 verocytotoxigenic Escherichia coli isolated from raw beef products using multiple-locus variable-number tandem repeat analysis

Verocytotoxigenic Escherichia coli (VTEC) can produce serious human illness linked to the consumption of contaminated food, mainly of bovine origin. There is growing concern about non-O157 VTEC serotypes, which in some countries cause severe infections in a proportion similar to O157:H7 strains. As several epidemiological studies indicated the important role of meat as the major vehicle in the transmission of this pathogen to human consumers, our aim was to investigate the genetic diversity among non-O157:H7 VTEC isolated from raw beef products. We performed a multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA), and to our knowledge, this is the first time that VTEC serotypes O8:H19, O112:H2, O113:NM, O171:NM, ONT:H7, ONT:H19, and ONT:H21 were typed by this method. MLVA typing grouped the total number of strains from this study (51) into 21 distinct genotypes, and 11 of them were unique. Several MLVA profiles were found in different serotypes, O178:H19 being the most variable. The isolates could be principally discriminated by alleles of three of seven loci studied (CVN001, CVN004, and CVN014), and on the other hand, CVN003 rendered null alleles in all the isolates. As some VNTR markers might be serotype specific, it is possible that the implementation of new VNTR loci will increase intraserotype discrimination.     

Real-time application of automated ribotyping and DNA macrorestriction analysis in the setting of a listeriosis outbreak

A cluster of three cases of listeriosis cases occurred against a background of endemic listeriosis in Western Australia. Human and environmental isolates of Listeria monocytogenes obtained during the outbreak investigation were rapidly subtyped by automated ribotyping using an EcoRI protocol and a RiboPrinter. DNA macrorestriction analysis by pulsed-field gel electrophoresis (PFGE) was used to confirm the relatedness of isolates. Serogroup 1/2 predominated among the food samples and the four clinical isolates from the outbreak cluster were also of this serogroup. All isolates from chicken material were serogroup 1/2 and indistinguishable by ribotype pattern. PFGE subdivided strains of this ribotype into four subtypes. The preliminary analysis had an immediate impact on hypothesis generation, environmental health investigations, environmental specimen collection and initial control measures. Sufficient typing data to guide environmental health and disease control initiatives was generated in less than one week by combining automated ribotyping with PCR-based detection of L. monocytogenes in suspect foodstuffs and an L. monocytogenes DNA probe. There were no further cases of bacteriologically confirmed listeriosis in Western Australia for six months after completion of the investigation.     

102株单核细胞增生李斯特菌随机扩增多态性DNA基因分型研究

目的:对单核细胞增生李斯特菌进行随机扩增多态性DNA(RAPD)基因分型研究。方法:以优化的随机引物和反应体系对生肉、熟肉、生奶、乳制品、水产品、冷冻食品、生食蔬菜共七大类食品中分离的102株单核细胞增生李斯特菌进行RAPD法基因分型,并按DNA条带数及片段大小绘制指纹图谱。结果:102株单核细胞增生李斯特菌共得26种RAPD指纹图谱,以第12、18、23和10型为主要型别,分别为15、14、8和6株。结论:RAPD技术可将单核细胞增生李斯特菌分型26种,我省食品中分离的单核细胞增生李斯特菌主要基因型为第12、18、23和10型。     

Molecular typing of Mannheimia (Pasteurella) haemolytica serotype A1 isolates from cattle in Japan

Pulsed field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) methods were applied for molecular typing of 130 Mannheimia (Pasteurella) haemolytica serotype A1 isolates obtained from 13 prefectures in Japan. These isolates were divided into 15 ApaI PFGE profiles that formed six distinct clusters (clusters A-F). Fifty-three (40.7%) isolates were classified in cluster B, and 20.0, 13.8, 12.3, 6.9 and 6.1% of isolates were in clusters E, A, F, D and C, respectively. The isolates of cluster B were differentiated into seven subtypes (B1-B7) and subtype B5 contained 63% (34/53) of isolates. RAPD revealed four banding patterns (types I-IV), and among 130 isolates 60.7% (79/130) of isolates were RAPD type I. All of the RAPD type I isolates were grouped into clusters A-C by PFGE. There was no relationship between molecular typing and geographic origin of these isolates. These results indicate that isolates of M. haemolytica A1 strain with various molecular profiles have already spread in Japan and may have caused sporadic infections.     

Distribution of internalin gene profiles of Listeria monocytogenes isolates from different sources associated with phylogenetic lineages

Listeria monocytogenes is a human foodborne pathogen with a broad range of hosts. While the L. monocytogenes genome encodes a number of internalins, which are leucine-rich repeat bacterial surface proteins with putative or confirmed roles in host cell attachment and invasion, the specific function of many internalins remains unclear. The distribution of 7 internalin genes (inlC, inlC2, inlD, inlE, inlF, inlG, and inlH) in 120 L. monocytogenes isolates from humans, foods, and animals was investigated to determine if the distribution of these proteins differed with respect to source or phylogenetic lineage. Isolates were classified into 6 different profiles based on internalin gene presence or absence, and a phylogeny based on one stress response (sigB) and two housekeeping (gap and prs) genes was used to correlate these profiles with L. monocytogenes phylogenetic lineages. All 69 isolates classified into L. monocytogenes lineage I, which is overrepresented among human disease cases, had the same internalin profile (presence of inlC and the inlC2DE operon). Lineage II (48 isolates), which is common among food and environmental sources, represented 4 internalin gene profiles, with most isolates carrying inlG and inlF in addition to inlC and inlC2DE. Our data indicate that L. monocytogenes isolates show diverse and distinct patterns of internalin gene presence/absence and L. monocytogenes internalin profiles are associated with phylogenetic lineages.     

Molecular characterization of Salmonella isolates by REP-PCR and RAPD analysis

Eighteen Salmonella isolates from both human and food (non-human) sources (fish, meat, and poultry) were characterized using conventional culture methods, biochemical, serological, and molecular analyses. REP-PCR and RAPD produced DNA profiles for differentiation purposes. Enterobacterial repetitive intergenic consensus (ERIC), repetitive extragenic palindronic (REP) and BOXAIR primers were selected for REP-PCR and two arbitrary primers, namely OPP-16 and OPS-11 were used for RAPD to generate DNA fingerprints from the Salmonella isolates. REP-PCR method showed greater discriminatory power in differentiating closely related strains of the related strains of Salmonella and produced more complex banding patterns as compared with RAPD. A dendogram was constructed with both sets of profiles using SPSS Version 13.0 computer software and showed that most human isolates were separately clustered from the non-human isolates. Two of the human isolates were closely related to some of the non-human isolates. A good correlation was also observed between the serogrouping of the O antigen and the molecular profiles obtained from REP-PCR and RAPD data of the Salmonella isolates. The results of a principal coordinate analysis (PCA) corresponded to the clustering in the dendrogram.