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PubMed1992

Investigation of an outbreak of methicillin-resistant Staphylococcus aureus in patients with skin disease using DNA restriction patterns.

OBJECTIVE: To investigate an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) among patients using chromosomal typing of the isolates. DESIGN: Comparison of epidemiological and clinical data to endonuclease restriction fragmentation analysis (RFA) of the MRSA isolates associated with an outbreak. Total DNA from the MRSA isolates was restricted with HINDIII and HAEIII for typing. SETTING: Tertiary care academic medical center. METHODS: An epidemiological investigation of an outbreak of MRSA among patients in private rooms was evaluated by routine infection control methods. The MRSA isolates from blood cultures of 7 patients and the nares of a nurse were collected during the outbreak. MRSA isolates from 23 patients not associated with the outbreak also were collected. The total DNA of the MRSA isolates were restricted with HINDIII and HAEIII and electrophoresed on 0.6% agarose gels. RESULTS: MRSA from 4 of the 7 bacteremic patients and the nurse on the outbreak unit had the same endonuclease restriction pattern. The patients were linked in that they were compromised by severe psoriasis or skin ulcers, were on the unit during the same period, and had oatmeal baths in a common bathtub. Of 50 staff members screened, the nurse was the only person detected as colonized by the strain. The other 3 patients on the unit as well as the 23 patients in other locations not associated with the outbreak had MRSA isolates with different RFA patterns. The use of the bathtub was discontinued and further transmission of MRSA was stopped. CONCLUSIONS: A comparison of the relatedness of MRSA by RFA demonstrated the uniqueness of the epidemiologically linked isolates and the utility of the RFA technique in the performance of routine infection control investigations.

Bacterial Typing Techniques↗

PubMed1992

Nosocomial diarrhoea due to a single strain of Clostridium difficile: a prolonged outbreak in elderly patients.

An outbreak of diarrhoea occurred in an acute geriatric ward of a hospital (A). It affected six patients initially and was found to be due to a single strain of Clostridium difficile. There was little evidence for asymptomatic carriage of this strain or others in the hospital patients. The following three months saw an increase in the number of symptomatic cases of C. difficile disease in two peripheral hospitals, B and C. Patients had been moved from the outbreak ward to these hospitals. Of 18 cases in hospital B all 15 isolates saved for typing were of the 'outbreak' strain. Of three cases occurring in hospital C, only one was the 'outbreak' strain (a relapsed patient who was part of the original episode). There were seven further cases in geriatric and medical wards of hospital A. All six typed isolates were also the outbreak strain. By chance, four isolates from hospital A and four from hospital B pre-dating the outbreak were also available for typing and seven of these were found to be identical to the outbreak strain. This suggests that one strain of C. difficile was endemic in geriatric and medical facilities on two sites and was responsible for nosocomial diarrhoea over at least one year. The problems of optimal management and infection control in this situation are discussed.

Aged↗

PubMed1990

Management of institutional outbreaks of Salmonella gastroenteritis.

The number of reports of outbreaks of salmonella gastroenteritis in hospitals has decreased since 1984 but the number of outbreaks in institutions such as old peoples' homes have increased during 1988. Foods, particularly chickens, remain a source of salmonellae and particular attention has to be paid to training and practices in food preparation areas. Staff who are convalescent are very unlikely to be sources of salmonella and do not need to be excluded unless they handle food that receives no further cooking. Outbreaks that do occur can usually be controlled by patient isolation and good control-of-infection measures and an effective Major Outbreak Control Plan is necessary. In some large old hospitals cross infection outbreaks may continue despite good control-of-infection measures. Antibiotics have been contraindicated in the treatment of salmonella gastroenteritis, but the new 4-quinolone antibiotics have demonstrated potential. Ciprofloxacin was used successfully in two outbreaks of salmonella gastroenteritis at a dose of 500 mg bd orally for seven days. Relapses did not occur and resistance did not develop. Ciprofloxacin should be considered as a therapeutic adjunct to control of infection measures in cross infection outbreaks in these situations.

Anti-Bacterial Agents↗

PubMed1989

Outbreaks of salmonella infection in hospitals in England and Wales 1978-87.

A total of 248 outbreaks of salmonella infection in hospital affecting over 3000 patients and 110 associated deaths were ascertained in England and Wales in 1978-87, compared with 522 outbreaks of salmonella in 1968-77. The largest reduction was found in outbreaks from children's units and maternity units. Fifty seven (24%) outbreaks were considered to be due to foodborne salmonellosis, and 70 (30%) were reported as person to person spread of the infection. The psychiatric hospital was the type of hospital in which foodborne outbreaks most often occurred, but the risk of being affected in an outbreak not due to food seemed to be highest in maternity units. Better control of infection and better surveillance should lead to earlier investigation and control of outbreaks.

Cohort Studies↗

PubMed1989

Results of routine restaurant inspections can predict outbreaks of foodborne illness: the Seattle-King County experience.

To analyze the association between the results of routine inspections and foodborne outbreaks in restaurants, we conducted a matched case-control study using available data from Seattle-King County, Washington. Case restaurants were facilities with a reported foodborne outbreak between January 1, 1986 and March 31, 1987 (N = 28). Two control restaurants with no reported outbreaks during this period were matched to each case restaurant on county health district and date of routine inspection (N = 56). Data from the routine inspection that preceded the outbreak (for case restaurants) or the date-matched routine inspection (for control restaurants) were abstracted from computerized inspection records. Case restaurants had a significantly lower mean inspection score (83.8 on a 0 to 100 point scale) than control restaurants (90.9). Restaurants with poor inspection scores and violations of proper temperature controls of potentially hazardous foods were, respectively, five and ten times more likely to have outbreaks than restaurants with better results. Although this study demonstrates that Seattle-King County's routine inspection form can successfully identify restaurants at increased risk of foodborne outbreaks, it also illustrates that more emphasis on regulation and education is needed to prevent outbreaks in restaurants with poor inspection results.

Disease Outbreaks↗

PubMed1990

[The main characteristics of outbreaks of hospital infections in the USSR in 1986-1988].

The analysis of 69 outbreaks of hospital infections in different regions of the USSR in 1986-1989 (the number of patients affected by these infections was 1,517) showed that most of these outbreaks (41) occurred at hospital wards for newborn infants. Acute enteric infections prevailed in the total structure of the outbreaks (73.7%). Purulent septic infections among newborns constituted a quarter of all outbreaks. Opportunistic microbes, and mainly Klebsiella, were the dominating element in the etiology of outbreaks in hospital wards for newborn infants. In pediatric wards in among adult hospital patients the etiology of outbreaks was completely, or almost completely, determined by pathogenic microorganisms, mainly salmonellae and shigellae. Outbreaks among hospital patients of three above-mentioned groups were characterized by differences in sources, routes and factors of the transmission of infection.

Adult↗

PubMed1988

Three outbreaks of yersinia pseudotuberculosis infection.

Three outbreaks of Yersinia pseudotuberculosis infection during 1982 to 1984 in Okayama Prefecture, Japan are described. In outbreak A, Yersinia pseudotuberculosis a causal organism was detected in 16 patients (serotype 5A). The latent period of the infection was 2 to 20 days estimating, from time of ingesting food suspected of being contaminated and onset of the illness. Outbreak B and C occurred in remote mountain areas. In outbreak B, Yersinia pseudotuberculosis bacilli were detected in the feces of 35 out of 276 people (serotype 4B in 34 stools, 2C and 4B in one stool). In outbreak C, 12 children became sick; one of the 4 patients whose stools were examined, showed an organism belonging to serotype 4B. The inhabitants in the area of outbreak B and C took unchlorinated mountain stream and well water for drinking. After the outbreak B and C, we examined water and wild animals fecea in these areas for the bacilli. As a result, they were detected in 3 out of 51 water samples (serotype 4A in one, 6 in 2 samples) and 2 out of 57 wild animal fecal samples (serotype 2C in 2 samples) in B area, and 4 out of 33 water samples (serotype 4A in 2, 4B in 2 samples) in C area.

Adolescent↗

PubMed1988

An outbreak of typhoid fever due to contamination of the municipal water supply in northern Israel.

An outbreak of typhoid fever followed a large outbreak of dysentery in northern Israel. Both outbreaks resulted from contamination of a drilled well that supplied water to the municipal water system. The well was contaminated with sewage from a broken main-pipe coming from Shefaram (an Arab town). The outbreak of typhoid involved 77 persons, of whom 75 were hospitalized. In 67, phage-type C1 (the phage type dominant in Shefaram since the 1950s) was isolated. The incubation period was relatively long, between 12 and 40 days (median 22) following exposure. Over 50% of the cases were children aged 0 to 14, and only two patients were older than 35 years; the sex ratio among the patients was 1:1. The incidence rate in Shefaram was 2.3 times higher than in the Krayot (outlying suburbs of Haifa). This difference was due mainly to the high incidence in young females in Shefaram. The opposite was observed during the outbreak of dysentery, when the attack rates of the disease were higher in the Krayot. Relapses occurred in 12% (9 cases). This outbreak demonstrates the potential that still exists for serious outbreaks due to contamination of the municipal water supply.

Adolescent↗

PubMed2026

Responding to a protracted tuberculosis outbreak: lessons from multiple rounds of investigation in a Chinese boarding school.

PURPOSE: This study analysed a multi-semester pulmonary tuberculosis (PTB) cluster outbreak in a Chinese boarding school to provide evidence for future epidemic control. METHODS: Contacts were screened via symptoms, infection tests and chest radiography. Screening expanded progressively from close contacts to same-floor contacts, then all students and staff. Whole-genome sequencing (WGS) with single nucleotide polymorphism (SNP) and bioinformatics analysis was used for lineage classification, transmission clustering (≤12 SNPs defining a cluster) and drug resistance prediction. RESULTS: From 2020 to 2022, 20 students were diagnosed with PTB, half laboratory-confirmed. Most cases clustered in class 16 and were epidemiologically linked to the primary case (case 0), who had household PTB exposure. Case 0 and case 1 had diagnostic delays exceeding 3 and 6 months, respectively. WGS of five isolates (case 1, 3, 4, 9 and 10) collected over three semesters showed all belonged to lineage 2 and differed by ≤12 SNPs, confirming the same transmission chain. The infection rate in class 16 (46.34%) was significantly higher than other case classes (19.05%) and classes without cases (8.27%) (χ2 = 61.169, p < 0.001). No new cases were detected during a one-year follow-up of students involved in the outbreak after the final round of screening, nor among household contacts of all cases followed up to the present. CONCLUSIONS: Lack of entry health examinations facilitated the outbreak. Delayed diagnosis, incomplete contact screening and absence of preventive treatment led to cross-semester persistence. The infection rate disparity confirms class 16 as the outbreak epicentre. Improving community case management, extending contact follow-up and enhancing cluster outbreak measures are recommended to prevent future outbreaks.

Humans↗

PubMed2025

Incorporating Epidemiological Data into the Genomic Analysis of Partially Sampled Infectious Disease Outbreaks.

Pathogen genomic data are increasingly being used to investigate transmission dynamics in infectious disease outbreaks. Combining genomic data with epidemiological data should substantially increase our understanding of outbreaks, but this is highly challenging when the outbreak under study is only partially sampled, so that both genomic and epidemiological data are missing for intermediate links in the transmission chains. Here, we present a new dynamic programming algorithm to perform this task efficiently. We implement this methodology into the well-established TransPhylo framework to reconstruct partially sampled outbreaks using a combination of genomic and epidemiological data. We use simulated datasets to show that including epidemiological data can improve the accuracy of the inferred transmission links compared with inference based on genomic data only. This also allows us to estimate parameters specific to the epidemiological data (such as transmission rates between particular groups), which would otherwise not be possible. We then apply these methods to two real-world examples. First, we use genomic data from an outbreak of tuberculosis in Argentina, for which data was also available on the HIV status of sampled individuals, in order to investigate the role of HIV coinfection in the spread of this tuberculosis outbreak. Second, we use genomic and geographical data from the 2003 epidemic of avian influenza H7N7 in the Netherlands to reconstruct its spatial epidemiology. In both cases, we show that incorporating epidemiological data into the genomic analysis allows us to investigate the role of epidemiological properties in the spread of infectious diseases.

Humans↗

PubMed2025

Temporal reconstruction of a Salmonella Enteritidis ST11 outbreak in New Zealand.

Outbreaks caused by Salmonella Enteritidis are commonly linked to eggs and poultry meat internationally, but this serovar had never been detected in Aotearoa New Zealand (NZ) poultry prior to 2021. Locally designated genomic cluster Salmonella Enteritidis_2019_C_01, was implicated in a 2019 outbreak associated with a restaurant in Auckland. Four Enteritidis_2019_C_01 sub-clusters have since been identified, two retrospectively, in the Auckland region. Authorities initiated a formal outbreak investigation after genomically indistinguishable S. Enteritidis was isolated from the NZ poultry production environment. This study analysed 231 S. Enteritidis genomes obtained from the outbreak using Bayesian phylodynamic tools to gain insight into the outbreak's dynamics and origin. We used Bayesian integrated coalescent epoch plots to estimate the change of the Enteritidis ST11 population size over time and marginal structured coalescent approximation to estimate transmission between poultry producers. We investigated human and poultry isolates to elucidate the time and location of the most recent common ancestor of the outbreak and transmission pathways. The median most recent common ancestor was estimated to be February 2019. We found evidence of amplification and spread of strain Enteritidis_2019_C_01 within the poultry industry, as well as transmission events throughout the production chain. The intervention by the public health and food safety authorities coincided with a drop in the effective population size of the S. Enteritidis ST11 as well as notified human cases. This information is crucial for understanding and preventing the transmission of S. Enteritidis in NZ poultry to ensure poultry meat and eggs are safe for consumption.

Salmonella enteritidis↗

PubMed1991

Analysis of plasmid pattern in paediatric intensive care unit outbreaks of nosocomial infection due to Enterobacter cloacae.

Sequential outbreaks of nosocomial infection due to multiply-resistant Enterobacter cloacae occurred in September 1987, and between December 1988 and January 1989, in a paediatric intensive care unit. A total of eight neonates were affected and most had received ventilatory support. Initially, we were unable to determine whether the two outbreaks were caused by the same strain of E. cloacae. After applying plasmid profile analysis to identify epidemic strains, we established that the strain from the first outbreak was different from the second outbreak strain, as each had its own plasmid pattern. During the second outbreak, an environmental bacteriological survey was carried out. We found that the distilled water containers were contaminated with E. cloacae which had the same plasmid profile. After changing the distilled water containers and by reinforcement of aseptic techniques, the nosocomial outbreak was terminated.

Cross Infection↗

PubMed1976

Detection of Serratia outbreaks in hospital.

Infections due to Serratia marcescens were studied in 23 different hospitals. A retrospective study was done in 4 hospitals; all isolates were compared by serological typing, antibiograms, bacteriocin production, and bacteriocin sensitivity. 2 of the hospitals were having cross-infection problems due to antibiotic-resistant strains, but the other 2 had little or no cross-infection. Outbreaks were studied in 19 other hospitals. 9 of these outbreaks were classified as "common source" since contaminated "sterile solutions" were incriminated as the cause in each. One hospital had a "pseudo-outbreak," in which Serratia from E.D.T.A. blood-collecting tubes contaminated blood-cultures as they were collected. All 10 of these strains from common-source outbreaks were generally sensitive to antibiotics. Outbreaks in 9 other hospitals resulted from cross-infection and were caused by strains which were very resistant to antibiotics. Guidelines for detecting outbreaks are given and control measures are suggested.

Alabama↗

PubMed1989

Outbreaks of diarrhoeal illness on passenger cruise ships, 1975-85.

We reviewed data from the Vessel Sanitation Program (VSP), established by the US Public Health Service in 1975, to describe the epidemiology of shipboard diarrhoeal outbreaks, determine the risk of outbreak-related illness among cruise ship passengers, and evaluate changes in rates and patterns of shipboard diarrhoeal illness since the VSP was implemented. When the programme began, none of the cruise ships passed periodic VSP sanitation inspections; since 1978, more than 50% of ships have met the standard each year. On cruises lasting 3-15 days and having at least 100 passengers, diarrhoeal disease outbreaks investigated by the Centers for Disease Control decreased from 8.1 to 3.0 per 10 million passenger days between 1975-79 and 1980-85. The proportion of outbreaks due to bacterial pathogens (36%) did not change. Seafood cocktail was implicated in 8 of 13 documented food-borne outbreaks. The risk of diarrhoeal disease outbreaks on cruise ships appears to have decreased since implementation of the VSP but has not been eliminated.

Diarrhea↗

PubMed1986

Widespread outbreaks of clam- and oyster-associated gastroenteritis. Role of Norwalk virus.

Consumption of raw shellfish has long been known to be associated with individual cases and sporadic outbreaks of enteric illness. However, during 1982, outbreaks of gastroenteritis associated with eating raw shellfish reached epidemic proportions in New York State. Between May 1 and December 31, there were 103 well-documented outbreaks in which 1017 persons became ill: 813 cases were related to eating clams, and 204 to eating oysters. The most common symptoms were diarrhea, nausea, abdominal cramps, and vomiting. Incubation periods were generally 24 to 48 hours long, and the duration of illness was 24 to 48 hours. Bacteriologic analyses of stool and shellfish specimens did not reveal a causative agent. Norwalk virus was implicated as the predominant etiologic agent by clinical features of the illness and by seroconversion and the formation of IgM antibody to Norwalk virus in paired serum samples from persons in five (71 percent) of seven outbreaks in which testing was done. In addition, Norwalk virus was identified by radioimmunoassay in clam and oyster specimens from two of the outbreaks. Determining the source of the shellfish was not always possible, but northeastern coastal waters were implicated. The magnitude, persistence, and widespread nature of these outbreaks raise further questions about the safety of consuming raw shellfish.

Antibodies, Viral↗

PubMed2026

Interspecies Exchange of Mobile Genetic Elements During a Plant Disease Outbreak.

Outbreak sequencing provides insight into the origin and evolutionary processes acting on emerging pathogens. Sequencing a historic multihost outbreak of Ralstonia spp. in Martinique shows the outbreak was caused by two lineages that diverged at separate times from mainland populations. One lineage (Ralstonia pseudosolanacearum I-18) was originally introduced from Asia to South America, where it became well established prior to its dissemination to Martinique, where it retains a signature of specialization on solanaceous hosts. The novel lineage first identified during the outbreak (Ralstonia solanacearum IIB-4NPB) arose from a mainland population endemic to the Americas prior to its arrival in Martinique, where host-range expansion was observed. In contrast to minor changes in secreted effector protein repertoires, the emergent R. solanacearum IIB-4NPB acquired a novel integrative and conjugative element (ICERsoRUN1145). After identifying all Ralstonia spp. ICEs and mapping their spatial and phylogenetic distribution among Ralstonia spp. sampled during the outbreak, we found closely related ICEs circulating in mainland populations of R. pseudosolanacearum, indicating likely exchange between introduced and endemic Ralstonia spp. The family of ICEs in Ralstonia (ICERs) has a conserved bipartite structure and display a striking pattern of functional specialization in each cargo gene insertion hotspot: the first hotspot is a target for metabolic gene acquisition, and the second is a target for defense element acquisition. This work provides unparalleled phylogenetic and spatial resolution of an unusual outbreak and highlights the role of horizontal transfer in shaping the ecological success of an emerging pathogen.

Plant Diseases↗

PubMed1989

Shigellosis outbreaks at summer camps for the mentally retarded in New York State.

During 1987, four New York State summer camps for the mentally retarded and developmentally disabled experienced outbreaks of Shigella sonnei gastroenteritis. Cases occurred in 150 of 286 (attack rate (AR) = 52%), 167 of 295 (AR = 57%), and 25 of 114 (AR = 22%) persons in three camps, respectively; a fourth camp reported eight cases. Epidemiologic investigation suggested point-source foodborne outbreaks in two camps, while person-to-person spread appeared to predominate in the other two. Numerous secondary cases were identified among contacts outside the facilities in the second and third camps. To quantify the extent of the problem, the authors reviewed data on 77 infectious disease outbreaks (12 in camps for the handicapped and 65 in camps for the nonhandicapped) that occurred in the 12,484 registered camp sessions (316 for the handicapped and 12,168 for the nonhandicapped) held during the six-year period 1982-1987. Camps for the handicapped demonstrated approximately a seven times greater risk for all types of infectious disease outbreaks (AR = 38 outbreaks/1,000 camp sessions vs. five outbreaks/1,000 camp sessions; relative risk (RR) = 7.1, 95% confidence interval (CI) 3.9-13.0), including those of gastrointestinal etiology (RR = 8.6, 95% CI 4.4-16.8) and those due to Shigella (RR = infinity). Large camp size (RR = 2.3, 95% CI 1.3-4.1) and long duration of camp sessions (RR = 3.9, 95% CI 1.3-11.6) also increased the risk for outbreaks; however, this risk was predominantly in the camps for the nonhandicapped--other factors relating to personal hygiene and close camper-staff contact were probably more important in the camps for the handicapped. These outbreaks demonstrate the impact of shigellosis at summer camps for the mentally retarded and the need for early preventive action.

Adult↗

PubMed1989

Treatment of an influenza A outbreak in a teaching nursing home. Effectiveness of a protocol for prevention and control.

The safety and efficacy of current ACIP guidelines for the prevention and control of influenza in nursing home populations are uncertain. An outbreak of influenza A/Sichuan (H3N2) in a teaching nursing home during 1988 gave us the opportunity to evaluate the effectiveness of an influenza vaccination and amantadine prophylaxis protocol. Over 13 days, 12 of 60 residents developed influenza. Prior influenza vaccination had been given to 94% of the residents. Protection from infection occurred in those tested who had antibody levels greater than or equal to 1:16 to the A/Leningrad (H3N2) antigen contained in the standard 1987-88 trivalent vaccine. However, five of 17 vaccinated residents who were tested had antibody levels less than or equal to 1:16 at the start of the outbreak. Amantadine (less than or equal to 100 mg/day) was given to all but one resident starting on the third day of the outbreak, and to employees starting on the sixth day of the outbreaks. Seven residents developed illness after the start of amantadine, although amantadine appeared to ameliorate their symptoms. Although amantadine was generally well tolerated by residents, employees receiving amantadine identified a high incidence of side effects and only 44% of employees took at least 70% of the prescribed amantadine. In our opinion, early detection and protocol-directed intervention probably abated a more severe influenza outbreak. Therefore we support existing recommendations that formal nursing home policies be established to ensure that residents and employees receive annual influenza vaccine and that chemoprophylaxis be used when outbreaks of influenza A are suspected.

Aged↗