Discrimination between endemic and feedborne Salmonella Infantis infection in cattle by molecular typing.

Salmonella enterica serovar Infantis is endemic in Finnish cattle. Feed contaminated with S. Infantis was distributed to cattle farms in May 1995. Following increased sampling, S. Infantis was detected on 242 farms in 1995. Molecular typing was used to differentiate the farms that were infected by the feed-related Infantis from those infected by other endemic strains. Twenty-three isolates from feed in 1995 and 413 from cattle (72 from 19924, 324 from 1995, 17 from 1996-7) were analysed. The feed-related Infantis was clonally related to the endemic infection by the ribotype, IS200-type and XbaI-profile. The feed isolates had a distinctive plasmid that appeared in pulsed-field gel electrophoresis as a 60 kb band when cleaved with XbaI or linearized by S1-nuclease. This plasmid appeared in cattle only since the outbreak and seemed stable on the follow-up farms. In addition to contact farms, the feedborne strain was found on 19% of the farms infected with S. Infantis in 1995 but not having bought suspected feedstuffs, possibly as secondary infections.     

Outbreak of campylobacteriosis following pre-cooked sausage consumption

OBJECTIVES: A small outbreak of campylobacteriosis involving three cases was investigated in terms of Campylobacter types present in the suspect food (pre-cooked sausages) and clinical samples from the cases. METHOD: Foods and faecal samples from people involved in the incident, which occurred in Christchurch, New Zealand, were tested for the presence of Campylobacter and identification of the species made. Isolates were typed by Penner serotyping and macrorestriction analysis using pulsed-field gel electrophoresis (PFGE). Investigations were conducted as to whether the contamination was on the surface or the interior of the sausages. RESULTS: All isolates from food and faecal samples were identified as C. jejuni and were indistinguishable from one another by the typing methods employed. Only the surfaces of the sausages were contaminated. Three other isolates of an indistinguishable subtype were isolated from campylobacteriosis cases in Christchurch occurring over approximately the same period. CONCLUSIONS AND IMPLICATIONS: Given the rarity of the subtype isolated from the three family members and the three other cases, it is possible that the outbreak was larger than the initial investigation revealed. It is likely that the sausages were contaminated after they had been cooked by the retailer and were not reheated prior to consumption. This report illustrates the role of cross-contamination in an outbreak with an unusual food vehicle for campylobacteriosis. Physical separation of cooked and raw product is necessary to prevent recurrences of outbreaks similar to the one described here.     

Human salmonellosis associated with young poultry from a contaminated hatchery in Michigan and the resulting public health interventions, 1999 and 2000

Although approximately 95% of disease caused by nontyphoidal salmonella is transmitted by foodborne vehicles, four documented salmonella outbreaks in the 1990s have been traced to contact with young poultry. No environmental studies of source hatcheries were completed. This case-control study was performed by comparing culture-confirmed Salmonella Infantis in Michigan residents, identified between May and July 1999, with two age- and neighbourhood-matched controls. Eighty environmental and bird tissue samples were collected from an implicated hatchery; all salmonella isolates underwent pulsed-field gel electrophoresis (PFGE) analysis. The study included 19 case-patients sharing the same PFGE subtype and 37 matched controls. Within 5 days before illness onset, 74% of case-patients resided in households raising young poultry compared with 16% of controls (matched OR 19.5; 95% CI 2.9, 378.1). Eight hatchery samples yielded Salmonella Infantis with PFGE subtypes matching the patients' isolates. This investigation identified birds from a single hatchery as the source of human illness and confirmed the link by matching PFGE patterns from humans, birds and the hatchery environment. Subsequent public health interventions reduced, but did not eliminate, transmission of poultry-associated salmonellosis. Five additional PFGE-linked cases were identified in Spring 2000, necessitating quarantine of the hatchery for depopulation, cleaning and disinfection.     

A community outbreak of Salmonella berta associated with a soft cheese product.

In September 1994, a complaint was registered at a public health unit concerning a cheese product. In addition, public health laboratories in Ontario reported an increase in the number of isolates of Salmonella berta from patients with diarrhoeal illness. A clinical, environmental and laboratory investigation was initiated to determine the nature of this outbreak. Isolates of Salmonella berta were compared using large fragment genomic fingerprinting by pulsed-field gel electrophoresis (PFGE). By late October, 82 clinical cases had been identified including 35 confirmed, 44 suspected and 3 secondary. The investigation linked illness to consumption of an unpasteurized soft cheese product produced on a farm and sold at farmers'' markets. Subtyping results of patient, cheese and chicken isolates were indistinguishable, suggesting that the cheese was contaminated by chicken carcasses during production. The outbreak illustrates the potential role of uninspected home-based food producers and of cross-contamination in the transmission of foodborne bacterial pathogens.     

食源性金黄色葡萄球菌流行特征、产肠毒素特性及耐药性研究

目的：了解食源性金黄色葡萄球菌流行特点及产肠毒素特性及其耐药性，为制定HACCP以防止金黄色葡萄球菌的食源性疾病提供依据。方法：采集8类食品1243件分离金黄色葡萄球菌并进行产肠毒素A—E试验及药物敏感试验。结果：从生肉、熟食、生奶、及水产品中分别分离出40株（10．96％）、12株（3．13％）、34株（16．27％）及1株（1．12％）金黄色葡萄球菌，相应的产肠毒素率分别达到52．50％、58．33％、61．76％、0．oo％；对青霉素、四环素、凝固酶阴性苯唑西林耐药率分别高达93．10％、49．43％、37．93％；79．31％菌株对2种以上的药物多重耐药，最多耐药种类达7种，表现出30种耐药谱。结论：扬州市食品中存在着较严重的金黄色葡萄球菌潜在的危害，主要来源于生肉、生奶及熟食；食源性金黄色葡萄球菌产毒素能力较强。金黄色葡萄球菌对多种药物的耐药性提示安全应用治疗药物的重要性。     

A statewide outbreak of Salmonella bovismorbificans phage type 32 infection in Queensland.

Between 30 May and 1 June 2001, 10 cases of Salmonella Bovismorbificans infection were reported to Public Health Services, Queensland Health. Investigations included enhanced surveillance, case interviews, a matched case control study, environmental audit and microbiological testing of faecal isolates (phage typing) and implicated food products. Forty-one cases of S. Bovismorbificans infection were detected, 36 cases were phage type 32. A matched case control study identified that illness was associated with consumption of food from 15 outlets of a fast food chain, Company A (matched odds ratio [MOR] 17.5, 95% CI 2.0-657.3, p = 0.004) and consumption of a particular product, Product X (MOR undefined, p < 0.001) in the week before onset of illness. Manufacturers of Product X ingredients were audited. Deficiencies were identified in equipment cleansing at the salad mixture processing plant (Manufacturer M). A swab of food residue behind the cutting wheel rim of the lettuce shredder was positive for S. Bovismorbificans phage type 32. This appears to be the first reported Australian outbreak of salmonellosis associated with a lettuce product. The investigations suggest that inadequate maintenance of cutting equipment to prepare lettuce ingredients for Product X by Manufacturer M was a key factor in this statewide outbreak. The statewide nature of this outbreak demonstrates the role of timely serovar identification of Salmonella isolates by a reference laboratory as an aid to outbreak identification, and the importance of adherence to appropriate food safety procedures in the manufacture and preparation of mass produced food items for the public.     

Neonatal infections with Pseudomonas aeruginosa associated with a water-bath used to thaw fresh frozen plasma

In our 15-bed neonatal intensive care unit (NICU), four new-borns were found to be colonized or infected with Pseudomonas aeruginosa within a period of one week. To identify the outbreak source, three independent studies were performed: epidemiological investigation, environmental surveillance and genotypic typing of isolates. Although epidemiological investigation by a case—control study revealed no conclusive results, the transfusion of fresh frozen plasma (FFP) and human albumin (HA) appeared to be the factor with highest risk. Environmental surveillance and random amplification of polymorphic DNA (RAPD) of isolates identified a water-bath used to warm FFP and HA as the likely reservoir for the outbreak. Further spread of the organism did not occur after elimination of this water-bath from the NICU. RAPD identified in addition an isolate from an infant hospitalized in the NICU five months before the outbreak with a pattern matching the one of the outbreak cluster.     

Prolonged hospital and community-based listeriosis outbreak caused by ready-to-eat scalded sausages

Listeria monocytogenes is a foodborne bacterial pathogen. Immunocompromised patients are at higher risk of developing invasive listeriosis with high fatality rates. After notification of two patients with Listeria that had stayed in the same hospital (hospital A) before the onset of infection, we began an investigation to ascertain the extent of the outbreak, identify its source and prevent further infections. We conducted active case finding by contacting hospital A, reviewing medical records and retrospectively investigating listeriosis notifications from the German surveillance system (SurvNet). The kitchen (hospital A) and its meat supplier (company X) were inspected and environmental and food samples were taken for microbiological testing. All isolates of L. monocytogenes, together with patient and food-related isolates from Baden-Württemberg 2006 to 2008, were characterised by pulsed-field gel electrophoresis (PFGE). Altogether, 16 cases of listeriosis were identified. Serotype 4b with the indistinguishable PFGE patterns (AscI 17a/ApaI 10) was detected from nine patients, five environmental and three ready-to-eat scalded sausage samples from company X, and two food samples from hospital A. All 11 patient cases linked to hospital A were immunosuppressed and were regularly served food during their hospital stay. Ten of these patients received corticosteroids and proton pump inhibitors (PPIs). Five cases were fatal. Our investigations indicate that ready-to-eat scalded sausages from company X caused this outbreak of listeriosis. Hospital food suppliers should guarantee the absence of L. monocytogenes in ready-to-eat meat products, controlled through optimised quality assurance.     

The role of roof rats ( Rattus rattus) in the spread of Salmonella Enteritidis and S. Infantis contamination in layer farms in eastern Japan

The prevalence of Salmonella in four layer farms in eastern Japan was investigated between 2004 and 2006 to determine the role of roof rats (Rattus rattus) in the epizootology of Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis). Persistent S. Enteritidis and S. Infantis contamination of the environment and pooled egg samples were detected in three out of four layer farms. A total of 113 (13.3%) and 158 (18.6%) out of 851 rats examined were positive for S. Enteritidis and S. Infantis, respectively. By pulsed-field gel electrophoresis, only one indistinguishable pulsed-field pattern was yielded by S. Enteritidis strains from rats, eggs and environmental samples from each of the two contaminated layer farms. Although, a variety of pulsed-field patterns were generated by S. Enteritidis isolates from rats, eggs, and the environment of the other contaminated farms, there are, however, some S. Enteritidis strains that are closely related clones. These results suggest that roof rats are carriers of S. Enteritidis and S. Infantis and that persistent S. Enteritidis and S. Infantis infections in a rat population may play an important role in the spread and maintenance of these pathogens inside the layer premises.     

Yersinia enterocolitica Outbreak Associated with Ready-to-Eat Salad Mix, Norway, 2011

In 2011, an outbreak of illness caused by Yersinia enterocolitica O:9 in Norway was linked to ready-to-eat salad mix, an unusual vehicle for this pathogen. The outbreak illustrates the need to characterize isolates of this organism, and reinforces the need for international traceback mechanisms for fresh produce.     

Outbreak of vancomycin-resistant enterococci in a burn unit.

OBJECTIVE: To investigate and control an outbreak of colonization and infection caused by vancomycin-resistant enterococci (VRE) in a burn intensive care unit (BICU). DESIGN: Epidemiological investigation, including multiple point-prevalence culture surveys of patients and environment, cultures from hands of healthcare workers (HCWs), pulsed-field gel electrophoresis (PFGE) typing of patient and environmental isolates, case-control study, and institution and monitoring of control measures. SETTING: BICU in an 800-bed university medical center in Galveston, Texas. RESULTS: Between June 6, 1996, and July 14, 1997, 21 patients were colonized by VRE, and 4 of these patients developed bacteremia. Of 2,844 environmental cultures, 338 (11.9%) were positive, but all hand cultures from HCWs were negative. PFGE typing indicated that the outbreak was clonal, with VRE isolates from patients differing by < or =4 bands from the index case. Thirteen of 14 environmental isolates varied by < or =4 bands from the pattern of the index case. A case-control study analyzed by exact logistic regression identified diarrhea (odds ratio [OR], 43.9; 95% confidence interval [CI95], 5.5-infinity; P=.0001) and administration of an antacid (OR, 24.2; CI95, 2.9-infinity; P=.002) as independent risk factors for acquisition of VRE. During a 5-week period in October and November 1996, all patient and 317 environmental cultures were negative for VRE. The outbreak recurred from a contaminated electrocardiogram lead that had not been identified during the prior 5 weeks. VRE were finally eradicated from the BICU in July 1997, using barrier isolation and a very aggressive environmental decontamination program. CONCLUSIONS: A VRE outbreak in a BICU over 13 months was caused by a single clone. After apparent eradication of VRE from a BICU, recrudescence of the outbreak occurred, evidently from a small inapparent source of environmental contamination. Changes in gastrointestinal (GI) tract function (motility) and administration of medications, other than antibiotics, that have an effect on the GI tract may increase the risk of GI tract colonization by VRE in burn patients. Application of barrier isolation and an aggressive environmental decontamination program can eradicate VRE from a burn population.     

Investigation of a pyoderma outbreak caused by methicillin-susceptible Staphylococcus aureus in a nursery for newborns

An outbreak of pyoderma caused by methicillin-susceptible Staphylococcus aureus occurred in a nursery for newborns over 26 days. During this period, six neonates were involved. The mother of the first case had trunk pyoderma before delivery, which was regarded as the source of the outbreak. Contamination of the environment and equipment were implicated as the reservoirs of further pathogen spread, as supported by pulsed-field gel electrophoresis (PFGE) results, which showed that some screening isolates were indistinguishable from the epidemic strain. Termination of the outbreak was achieved by the reinforcement of infection control practices and disinfection of environmental surfaces.     

Blood invasiveness of Salmonella enterica as a function of age and serotype

We explored the dual influence of the patient's age and the infecting serotype on the blood invasiveness patterns of non-Typhi Salmonella enterica (NTS). Blood invasiveness ratio (BIR) was calculated as the ratio between the number of blood and blood + stool isolates. Analysis of 14,951 NTS isolates showed that the BIR increased drastically above the age of 60 years, reaching levels 3.5-7 times higher compared to age group < 2 years. Different patterns of age-related invasiveness were observed for the five most common NTS serotypes (Enteritidis, Typhimurium, Virchow, Hadar, Infantis). Among children < 2 years, the BIR was highest for serotype Virchow and lowest for serotype Hadar, while in persons > or = 60 years it was highest for serotypes Enteritidis and lowest for serotype Infantis. The tendency of NTS serotypes to invade the bloodstream was significantly influenced by the patient's age, however the impact of age differed for various NTS serotypes.     

福氏志贺菌4c型暴发和散发菌株的脉冲场凝胶电泳分型

目的了解杭州地区福氏志贺菌4c型暴发菌株和散发菌株的分子分型特征。方法对2003和2005年杭州地区的2次食物中毒暴发分离的福氏志贺菌菌株（暴发1和暴发2,菌株数分别为13株和12株）和2005年1例散发腹泻患者分离的福氏志贺菌4c型离株（1株）进行生化鉴定和血清分型,PCR检测侵袭性抗原基因ipaH,改良Kirby-Bauer纸片法检测菌株的耐药谱及脉冲场凝胶电泳（pulse field gel electrophoresis,PFGE）进行分子分型。结果暴发1中分离的13株菌株均为福氏4c型,但检测的6株菌株间的PFGE图谱存在着相当的差异,Dice系数为0．78至0．92。暴发2中分离的菌株有10株福氏4c型和2株福氏x型,所有菌株的PFGE图谱几乎完全一致。暴发2分离株和暴发1的部分分离株可能存在着一定相关性（Dice系数大于0．8）,而散发菌株与2起暴发的绝大部分菌株间的距离较远（Dice系数小于0．8）。暴发1、暴发2的分离株和1株散发菌株对14种抗生素的耐药谱略呈差异,暴发2中分离的福氏4c型和x型菌株的耐药谱一致。结论PFGE能够很好地辨别福氏志贺菌4c型的两起暴发菌株和1株散发菌株。福氏志贺菌4c型菌株具有易变性,可在暴发流行过程中产生PFGE图谱的差异、血清亚型的转换、耐药谱的变化等。     

Outbreak of Vibrio parahaemolyticus Sequence Type 120, Peru, 2009

In 2009, an outbreak of Vibrio parahaemolyticus occurred in Piura, Cajamarca, Lambayeque, and Lima, Peru. Whole-genome sequencing of clinical and environmental samples from the outbreak revealed a new V. parahaemolyticus clone. All the isolates identified belonged to a single clonal complex described exclusively in Asia before its emergence in Peru.     

Comparative genomic analysis of two isolates of Vibrio cholerae O1 Ogawa El Tor isolated during outbreak in Mariupol in 2011

Cholera is a water-borne, severe enteric infection essentially caused by toxigenic strains of Vibrio cholera O1 and O139 serogroups. An outbreak of cholera was registered during May–July 2011 in Mariupol, Ukraine, with 33 cholera cases and 25 carriers of cholera. Following this outbreak, the toxigenic strain of V. cholerae 2011EL-301 was isolated from seawater in the recreation area of Taganrog city on the territory of Russia. The aim of our study was to understand genomic features of Mariupol isolates as well as to evaluate hypothesis about possible interconnection between the outbreak of cholera in Mariupol and the single case of isolation of V. cholerae from the Sea of Azov in Russia. Mariupol isolates were phenotypically characterized and subsequently subjected to whole genome sequencing procedure. Phylogenetic analysis based on high-quality SNPs of V. cholera O1 El Tor isolates of the 7th pandemic clade from different regions showed that clinical and environmental isolates from Mariupol outbreak were attributable to a unique phylogenetic clade within wave 3 of V. cholera O1 El Tor isolates and characterized by six clade-specific SNPs. Whereas Taganrog isolate belonged to distantly related clade which allows us to reject the hypothesis of transmission the outbreak strain of V. cholerae O1 from Ukraine to Russia in 2011. Mariupol isolates shared a common ancestor with Haiti\Nepal-4\India clade indicating that outbreak progenitor strain most likely originated in the South Asia region and later was introduced to Ukraine. Moreover, genomic data both based on hqSNPs and similarity of virulence-associated mobile genomic elements of Mariupol isolates suggests that environmental and clinical isolates are a part of joint outbreak which confirms the role of contaminated domestic sewage, as an element of the complex chain of infection spread during cholera outbreak. In general, the genome-wide comparative analysis of both genes and genomic regions of epidemiological importance indicates accessory of this isolates to ‘new’ clone of toxigenic multiple drug resistance atypical variant of V. cholerae O1 El Tor.     

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.     

An outbreak of multidrug-resistant Salmonella enterica serotype Oranienburg in Michigan dairy calves

The objectives of this study were to report an outbreak of highly drug-resistant Salmonella enterica serotype Oranienburg in dairy calves, and conduct an epidemiological investigation of Oranienburg identified on a dairy herd during a study to determine whether discontinuing feeding medicated milk replacer to preweaned dairy calves resulted in increased antimicrobial susceptibility in enteric bacteria. Calf fecal samples and swabs of calf and maternity pens were collected monthly over 18 months. Samples were streaked onto XLT-4 agar and characteristic colonies were subjected to biochemical tests to confirm Salmonella. Strain relatedness was examined by Xbal and BlnI pulsed-field gel electrophoresis analysis on 62 randomly selected isolates. Antimicrobial susceptibility testing, using automated microbroth dilution, was conducted using a panel containing tetracycline, amikacin, amoxicillin-clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, cefoxitin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, and trimethoprim-sulfamethoxazole. A total of 190 Salmonella spp. were isolated from 604 calf and 36 pen samples, of which 86% were Oranienburg and 97% were resistant to at least 9 agents. Environmental isolates had lower levels of resistance than fecal isolates. Pulsed-field gel electrophoresis analysis identified three strains: the most common strain was consistently present before the outbreak and at its peak. One strain was exclusively an environmental isolate, with little antimicrobial resistance. Multiresistant isolates with resistance to ciprofloxacin appeared early in the outbreak, and were replaced by multiresistant isolates with resistance to cephalothin. The differences in strains and resistance patterns suggest that the strains of Oranienburg found in fecal isolates may have different origins from environmental isolates.     

Critical care unit outbreak of Serratia liquefaciens from contaminated pressure monitoring equipment

Between October and December 1999, Serratia liquefaciens was isolated from 11 patients in an adult critical care unit. One patient was infected on two separate occasions. In total, there were 10 positive blood cultures and five positive intravascular catheter tips. Eight cases were clinically infected, three were possibly infected and one was not. All patients with clinical isolates received appropriate empirical antibiotic treatment and responded well. Environmental investigation revealed S. liquefaciens in syringes and connector tubing used to calibrate the intravascular line pressure monitoring equipment of eight patients. Three of these patients also had clinical isolates of S. liquefaciens. Analysis by pulsed-field gel electrophoresis found clinical and environmental isolates to be of the same strain. The most likely mode of transmission was a non-sterile sphygmomanometer tip used daily for calibration. Inadequate microbiological sampling methods may have limited detection of S. liquefaciens. Several other examples of poor infection control techniques were identified during the outbreak, notably lapses in hand hygiene during intravascular pressure monitoring. It was also observed that unlabelled multidose heparin and insulin vials were shared between patients and personal hand creams were used by staff. However, these were not directly implicated in the outbreak. The outbreak ended when poor infection control practices were corrected. Calibration syringes and connector tubing were discarded after a single use. The sphygmomanometer was replaced by a pneumatic pressure transducer tester with connector tube and the frequency of calibration reduced to a single test following line insertion only. The non-disposable tube was disinfected with alcohol wipes between patients.     

安仁县2012年一起霍乱暴发疫情的流行病学分析

目的 查明安仁县2012年5月份发生的一起霍乱疫情规模、调查传染来源,以控制疫情蔓延. 方法 制定统一的病例定义,开展病例主动搜索,对就餐人员食用菜谱开展回顾性队列研究. 结果 共18人感染,其中有3例确诊病例,均参加了2012年4月29日一次农村家庭丧宴晚餐聚餐,未参加者未发病.对参加29日晚餐的373名就餐者开展回顾性队列研究,结果显示食用猪脚蒸鸡蛋为危险因素(RR=4.64,95％CI:1.08～19.9).在食品加工过程中甲鱼宰杀后和煮熟去壳鸡蛋共用器具盛装,部分去壳鸡蛋未再经油炸和蒸煮即直接与猪脚一起上酒席,存有交叉污染可能.结论 该起疫情为农村家庭丧宴中食品受O139霍乱弧菌污染所致,传染源为带菌的甲鱼,传播途径为甲鱼制作过程中污染了鸡蛋,经食用后引起发病.