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PubMed1999

Restriction fragment length polymorphisms analysis by pulsed-field gel electrophoresis for discrimination of Staphylococcus aureus isolates from foodborne outbreaks.

A number of outbreaks of disease due to Staphylococcus aureus occurring in Aichi-ken, Japan, have provided the opportunity to investigate aspects of the molecular epidemiology of this and related organisms. Coagulase types, enterotoxin types, phage types, and restriction fragment length polymorphisms (RFLPs) as assessed by pulsed-field gel electrophoresis (PFGE) was performed for S. aureus infections diagnosed in the area of Aichi-ken. Among the 56 isolates of S. aureus from 30 outbreaks, 15 distinctive RFLP types were found by digestion with the restriction enzyme, SmaI. A total of 32 isolates from patients, foodstuffs and cooks on six occasions had the same RFLP types, coagulase types, enterotoxin types and phage types in the same outbreaks. Moreover, the coagulase and phage types could be separated in terms of RFLP. In one outbreak, ten isolates, which were derived from six patients, two foodstuffs and two cooks, had the same coagulase type, enterotoxin type, phage type, and RFLP type. This PFGE method may therefore prove useful for subclassifying S. aureus and differentiating isolates of the same coagulase types and phage types derived from sporadic cases and those derived from foodborne outbreaks.

Bacteriophage Typing↗

PubMed2003

Gastroenteritis outbreak with norovirus in a Swiss university hospital with a newly identified virus strain.

We report an outbreak of norovirus-associated gastroenteritis in patients and healthcare workers (HCWs) at a university hospital in Switzerland during the period from 28 February to 31 March 2001. Faecal and vomitus specimens and bottled and drinking water were investigated for norovirus by reverse transcriptase-polymerase chain reaction (RT-PCR) Sixty-three patients and HCWs were affected. 37% of the investigated stool specimens were positive for norovirus. Sequencing showed a new phylogenetic strain, "Basel". There was no evidence for a water-borne, foodborne or environmental source. The source of the outbreak was most likely a patient admitted to the hospital. Once an outbreak was suspected, measures were instituted based on published guidelines, such as isolation of patients and excluding sick HCWs from work. However, the application of the guidelines proved difficult. A first realistic goal in such situations is to limit spread of the disease to other areas, specifically to high-risk areas such as intensive care and haemato-oncology units. Optimal management includes a rapid diagnosis of norovirus, written recommendations for management of affected patients and HCWs, and cleaning of surfaces with an effective disinfectant. These recommendations should be available in written form well before such an outbreak is in progress. Such preparations may limit the extent of the outbreak, but norovirus infection in a hospital will probably spread despite infection control interventions.

Aged↗

PubMed1996

An outbreak of multiply-resistant Klebsiella pneumoniae in the Grampian region of Scotland.

A predominantly hospital-based outbreak of multiply-resistant Klebsiella pneumoniae capsular type K2 (MRK) expressing expanded spectrum betalactamase (ESBL) activity and fully sensitive only to the carbapenems and amikacin is described. The organism was isolated from 283 patients between March 1992 and September 1995. The outbreak started in the intensive care unit (ICU) of a major acute hospital and spread through surgical wards, a medical ward, a geriatric unit in a separate hospital and various other local hospitals. Environmental screening revealed extensive ward contamination. The decline of the outbreak after the spring of 1995 coincided with the re-emphasis of standard infection control procedures and the launch of a works programme aimed at addressing underlying sites of environmental contamination. Of the 283 cases, 166 (59.0%) were detected through a specially instigated case finding programme. The MRK caused 11 cases of septicaemia, two postoperative intra-abdominal abscesses, one case of postoperative meningitis, 102 cases of urinary tract infection and 28 wound infections and was isolated from the respiratory tracts of five patients with ventilator associated pneumonia. The difficulty in controlling the outbreak is ascribed to heavy environmental contamination, frequent inter- and intra-hospital patient transfers and prolonged carriage of the outbreak strain.

Anti-Bacterial Agents↗

PubMed1997

Application of molecular methods to a nosocomial outbreak of Salmonella enteritidis phage type 4.

A nosocomial outbreak of Salmonella enteritidis phage type 4 occurred in July 1995. Seven definite cases were identified over 13 days affecting four wards in a London hospital. The outbreak strain was characterized by plasmid profile typing and pulsed-field gel electrophoresis (PFGE), and was unusual in that it did not possess a 38 MDa plasmid common to most isolates of S. enteritidis PT 4 made from humans and food animals in England and Wales. Seven asymptomatic excreters were identified on screening. No additional cases occurred on wards after standard isolation procedures were implemented. No common or continuing food or dietary source was identified. Results of epidemiological, microbiological and environmental investigations suggested that the outbreak was due to person-to-person transmission within the hospital. The source of the outbreak was not established but was probably due to admission of a patient with an unrecognized infection of S. enteritidis PT 4. The study highlights the importance of close collaboration between hospital staff, epidemiologists and microbiologists, and demonstrates the value of molecular techniques for strain subdivision in outbreak investigations.

Aged↗

PubMed1998

A hospital outbreak of extended-spectrum beta-lactamase-producing Klebsiella pneumoniae investigated by RAPD typing and analysis of the genetics and mechanisms of resistance.

Between July and September 1997 a ceftazidime- and aminoglycoside-resistant strain of Klebsiella pneumoniae infected or colonized seven patients on three paediatric wards at Guy's Hospital in London. The patients were mostly neonates or infants recovering from cardiac surgery for congenital defects. The organism was probably introduced by an asymptomatic patient from Greece and the subsequent outbreak could largely be explained by person-to-person spread on individual wards and frequent transfers of patients between wards. The outbreak was controlled by patient isolation and attention to handwashing, and there were no fatalities. The organisms were non-typeable by serology but had a characteristic RAPD profile. They produced the extended spectrum beta-lactamase SHV-5 and the aminoglycoside-modifying enzymes AAC(6') + probably AAC(3)II, encoded on a conjugative plasmid of approximately 160 kb. Two other patients had multi-resistant klebsiellas, one of them an SHV-5 producer and one a TEM-5 producer, but these could be distinguished from each other and from the outbreak strain by serological and RAPD typing and by the genetics and mechanisms of their resistances. Three other multi-resistant enterobacteria were isolated during the outbreak: an Escherichia coli that had acquired the 160 kb resistance plasmid from the epidemic klebsiella, a Citrobacter isolated from one of the patients with the klebsiella but which did not produce SHV-5, and a TEM-5-producing Enterobacter. This outbreak illustrates the importance of screening patients from high-risk areas for multiply-resistant organisms on admission, and the value of bacterial typing and analysis of resistance mechanisms to define the epidemiology of hospital infection.

Adult↗

PubMed1998

Ventilation grilles as a potential source of methicillin-resistant Staphylococcus aureus causing an outbreak in an orthopaedic ward at a district general hospital.

The spread of methicillin-resistant Staphylococcus aureus (MRSA) in a hospital is thought to be mainly by direct contact. Environmental sources such as exhaust ducting systems have been increasingly recognized as a source for MRSA outbreaks in intensive therapy units. We describe an outbreak of MRSA related to ventilation grilles in an orthopaedic ward. Six patients and one nurse were involved in an outbreak with EMRSA-15 during March 1996. The index case was transferred from a large university hospital in Leeds. One of the patients had shared the same bay with the index case. The rest of the patients were in another bay of the same ward and had no direct contact with the index patient. An environmental source was suspected and the ventilation grilles in boys 1 and 2 were found to be harbouring EMRSA-15. The ventilation system at that time was working on an intermittent cycle from 4 p.m.-8 a.m. Daily shut-down of the system temporarily created a negative pressure, sucking air in from the ward environment into the ventilation system and probably contaminating the outlet grilles. It is likely that contaminated air was blown back into the ward when the ventilation system was started. The system was thoroughly cleaned, appropriate infection control measures were instituted and the ventilation system was put back on a continuous running cycle and the outbreak terminated. Six months after the outbreak no isolates of EMRSA-15 had been made on the ward.

Air Microbiology↗

PubMed1999

An outbreak of Bacillus cereus respiratory tract infections on a neonatal unit due to contaminated ventilator circuits.

An outbreak of Bacillus cereus respiratory tract infections affecting six ventilated preterm neonates over a two-week period is described. Reusable ventilator circuits were identified as the cause of the outbreak. Ordinarily these were reprocessed on the Neonatal Unit (NNU), first through a washing machine and then through a low-temperature steam (LTS) disinfector. The onset of the outbreak coincided with a breakdown of the LTS facility, which necessitated sending the washed circuits off site for LTS disinfection. The washing machine was shown to be contaminated with the same serovars of B. cereus as those isolated from patients. Two critical steps in the off site LTS disinfection process allowed exsporulation and multiplication of B. cereus: the circuits were inadequately dried after processing, whilst return of the moist circuits to the NNU was often delayed. The outbreak was terminated by withdrawal of the heat-disinfected ventilator circuits. This outbreak emphasizes the need for high standards where medical equipment is reprocessed, especially for use in vulnerable patients.

Bacillaceae Infections↗

PubMed1993

Evaluation of an outbreak of foodborne illness initiated in the emergency department.

STUDY OBJECTIVES: For many foodborne outbreaks, the pathogen and food vehicle never are identified. Delayed collection of epidemiologic and microbiologic information may contribute to this. We postulated that collection of this information from ill persons as they presented to the emergency department during a recent outbreak might contribute to earlier identification of the pathogen and vehicle. DESIGN: At least 690 of 1,900 conventioneers developed gastrointestinal symptoms after attending a banquet. A questionnaire was developed to collect information on specific food histories, incubation periods, symptoms, physical findings, and demographics. These results were compared with results of investigations by the city and state departments of public health. SETTING: The ED of Rush-Presbyterian-St Luke's Medical Center, a tertiary care university hospital in Chicago, Illinois. TYPE OF PARTICIPANTS: Adults (24 men and nine women) presenting to the ED with gastrointestinal symptoms after eating a common meal. MEASUREMENTS AND MAIN RESULTS: The clinical syndrome suggested an invasive pathogen. Based on this, clinical microbiology laboratory procedures were modified (isolation plates were reviewed during the evening shift). This led to early identification of the first isolates (Salmonella enteritidis) from the outbreak. The questionnaire also narrowed the vehicle to one of two foods served. Investigations by the departments of public health subsequently identified one of these, bread pudding with a raw egg based-sauce, as the vehicle. CONCLUSION: Outbreak evaluations can begin in the ED or any other patient care facility. This evaluation need not always add significantly to the expenditure of time, manpower, or laboratory studies. The evaluation of even a small percentage of ill persons from a large outbreak may provide useful epidemiologic information and be particularly important in settings with limited public health resources.

Adult↗

PubMed2000

Direct costs associated with a nosocomial outbreak of Salmonella infection: an ounce of prevention is worth a pound of cure.

BACKGROUND: Nosocomial outbreaks of Salmonella infections in Australia are an infrequent but significant source of morbidity and mortality. Such an outbreak results in direct, measurable expenses for acute care management, as well as numerous indirect (and less quantifiable) costs to those affected, the hospital, and the wider community. This article describes the significant direct costs incurred as a result of a nosocomial outbreak of Salmonella infection involving patients and staff. METHOD: Information on costs incurred by the hospital was gathered from a number of sources. The data were grouped into 4 sections (medical costs, investigative costs, lost productivity costs, and miscellaneous) with use of an existing tool for calculating the economic impact of foodborne illness. RESULTS: The outbreak cost the hospital more than AU $120, 000. (US $95,000). This amount is independent of more substantial indirect costs. CONCLUSION: Salmonella infections are preventable. Measures to aid the prevention of costly outbreaks of nosocomial salmonellosis, although available, require an investment of both time and money. We suggest that dedication of limited resources toward such preventive strategies as education is a practical and cost-effective option for health care facilities.

Cross Infection↗

PubMed1992

Measles: lessons from an outbreak.

BACKGROUND: Measles outbreaks continue to be a problem for infection control in hospitals--patients, personnel, and employee health service. Guidelines for measles outbreaks are not clear for medical personnel in the hospital. METHODS: Outbreak investigation in a university-affiliated teaching hospital. RESULTS: Four primary cases resulted in 607 staff exposures and two secondary cases. Forty-seven medical personnel were furloughed and 88 were vaccinated for measles. Minimal serologic criteria for immunity were found to be inadequate in the outbreak setting. CONCLUSIONS: We found that serologic guidelines for assessing immunity to measles are inadequate. During the outbreak, we arbitrarily doubled the acceptable enzyme-linked immunosorbent assay titers that we would consider protective, > or = 2, to decrease the possibility of further secondary cases. Employees with enzyme-linked immunosorbent assay measles titers less than 2 and without a definite history of natural measles were revaccinated with a measles vaccine. This strategy takes advantage of the anamnestic response that revaccination would confer in persons with low antibody titer.

Adult↗

PubMedDate not supplied

[Waterborne outbreak of gastroenteritis transmitted through the public water supply].

INTRODUCTION: The chlorination of public water supplies has led researchers to largely discard drinking water as a potential source of gastroenteritis outbreaks. The aim of this study was to investigate an outbreak of waterborne disease associated with drinking water from public supplies. METHODS: A historical cohort study was carried out following notification of a gastroenteritis outbreak in Baqueira (Valle de Arán, Spain). We used systematic sampling to select 87 individuals staying at hotels and 67 staying in apartments in the target area. Information was gathered on four factors (consumption of water from the public water supply, sandwiches, water and food in the ski resorts) as well as on symptoms. We assessed residual chlorine in drinking water, analyzed samples of drinking water, and studied stool cultures from 4 patients. The risk associated with each water source and food type was assessed by means of relative risk (RR) and 95% confidence intervals (CI). RESULTS: The overall attack rate was 51.0% (76/149). The main symptoms were diarrhea 87.5%, abdominal pain 80.0%, nausea 50.7%, vomiting 30.3%, and fever 27.0%. The only factor associated with a statistically significant risk of disease was consumption of drinking water (RR = 11.0; 95% CI, 1.6-74.7). No residual chlorine was detected in the drinking water, which was judged acceptable. A problem associated with the location of the chlorinator was observed and corrected. We also recommended an increase in chlorine levels, which was followed by a reduction in the number of cases. The results of stool cultures of the four patients were negative for enterobacteria. CONCLUSIONS: This study highlights the potential importance of waterborne outbreaks of gastroenteritis transmitted through drinking water considered acceptable and suggests the need to improve microbiological research into these outbreaks (viruses and protozoa detection).

Disease Outbreaks↗

PubMed2002

An outbreak of mumps in the metropolitan area of Walsall, UK.

OBJECTIVE: To describe the epidemiology of excessive mumps cases during the year 2000, within the metropolitan area of Walsall, UK; to assess the impact of the mumps outbreak on morbidity; and to inform future communicable disease control strategy. METHODS: Demographic records, school attendance, uptake of the measles-mumps-rubella (MMR) vaccine, and mumps-associated admission to hospital, were reviewed for all Walsall residents diagnosed and notified with mumps during the year 2000. RESULTS: There were 200 mumps notifications in 2000 (76.6 per 100,000), representing the highest incidence in England. Only 91 of the notified cases were salivary antibody positive for mumps IgM, and 32 were negative, although 77 were not tested. Since 1990, annual totals have never previously exceeded 20. Over 90% of patients were <20 years old, with a peak age group of 10-14 years; 88% attended schools located within Walsall. The pattern of spread suggested that the outbreak proceeded through schools from north to south in the more deprived western half of the metropolitan area. Most cases (136, 68%) had received one (99, 49.5%) or two (37, 18.5%) doses of MMR vaccine; cases > or =20 years old had never received MMR. Six cases (aged 4-14 years) were admitted to hospital, all with a successful outcome, including one male with meningitis and one female with pancreatitis. Current uptake of the MMR vaccine at 24 months has dropped to below 90% in recent years, as in most parts of the UK. CONCLUSIONS: Future mumps outbreaks in schools, and among older age groups, can be predicted, since most older children and young adults have received only one dose of MMR vaccine or no vaccination at all. Primary vaccine failure is well described in mumps, and cases during outbreaks can include recipients of two MMR vaccine doses. It was fortunate that no severe morbidity was associated with this outbreak (prior to MMR, two to four mumps deaths occurred annually in England and Wales). Measures to restore the uptake of MMR to the previous levels of above 90-95% will be necessary to reduce the risk of the mumps virus circulating within communities. Older children are susceptible, and it may be advisable to ensure second-dose MMR uptake while they are still at or when they leave school, or when they enter college, university or the military.

Adolescent↗

PubMedDate not supplied

Post mass-immunization measles outbreak in Taoyuan County, Taiwan: dynamics of transmission, vaccine effectiveness, and herd immunity.

OBJECTIVES: Analysis of national surveillance data and a seroepidemiologic investigation were conducted to elucidate the causes and epidemiologic characteristics of a measles outbreak in Taoyuan, Taiwan, 1994. METHODS: Measles cases were identified through a national surveillance system. Reported cases and their physician or school nurses were interviewed to trace additional suspect cases and were sampled for serologic diagnosis. Measles-specific IgG and IgM were assayed. A confirmed case was defined as being positive for measles IgM test but not having received measles vaccination within the previous 3 months. RESULTS: The outbreak began in Taoyuan City in December 1993 and continued to spread in primary schools and kindergartens, but caused only sporadic cases in neighboring towns. Among 42 confirmed cases, 15 (38%) were primary school children and 16 (38%) were kindergarten children. Among 24 confirmed cases with a vaccination record, 7 had one dose of vaccination, 4 had two doses of vaccination, and 13 (54%) were unvaccinated. The overall measles susceptible proportion at a kindergarten before the outbreak was 8.1% (17/209) and the overall measles cumulative incidence among susceptibles was 0.65 (11/17). CONCLUSIONS: A measles vaccination coverage of 82% with the first dose at 9 months of age and 63% with the second dose (measles, mumps, and rubella) at 15 months was inadequate to block measles virus circulation in Taoyuan City in 1994. The city center, with a growing population, represents a high risk as an epicenter for measles outbreaks. Measles outbreaks may occur in a school population with 92% herd immunity.

Antibodies, Viral↗

PubMed2005

A veterinarian's experience of the spring 2004 avian influenza outbreak in Laos.

Since it was first reported in December 2003, the outbreak of avian influenza A/H5N1 has spread to at least nine countries in Asia, affected multiple species of animals, and caused at least 42 human deaths. The magnitude and extent of this zoonotic outbreak are unprecedented, continue to grow, and threaten the start of a global human influenza pandemic. Control of the H5N1 outbreak has required the implementation of integrated human and veterinary health surveillance and response efforts. These efforts have also necessitated an unprecedented level of bilateral and multilateral international communication and cooperation. This report describes the contribution of one public-health veterinarian to the H5N1 outbreak response effort in Laos, and emphasises the value of multidisciplinary approaches to addressing this and future emerging infectious disease outbreaks.

Animals↗

PubMed2004

Managing obstetrical patients during severe acute respiratory syndrome outbreak.

Severe Acute Respiratory Syndrome (SARS) is a newly described infectious disease caused by a coronavirus. Two outbreaks occurred in Toronto in the spring of 2003, resulting in the closure of 3 hospitals, including 2 obstetrical units. Strategies, devised using information about the coronavirus available at the time, as well as epidemiologic and infectious disease containment measures, were initiated to protect obstetrical patients and staff. In the first outbreak, the obstetrical unit of an affected Toronto hospital was kept open while other clinical services were closed. In the second outbreak, the obstetrical unit was closed along with all other clinical activities. This report details the stepwise processes used to make decisions during the SARS outbreaks and the implementation of the decisions made. It is recommended that these or similar protocols be used when an obstetrical unit is confronted with a large-scale nosocomial infectious outbreak that has a mechanism of transmission similar to that of SARS.

Cross Infection↗

PubMed2025

Investigation of a Mycobacterium fortuitum prosthetic joint infection outbreak at two ambulatory surgery centers in Tennessee.

OBJECTIVE: This study outlines the investigation into an outbreak of Mycobacterium fortuitum infections involving 17 cases undergoing hip or knee surgeries at two ambulatory surgery centers (ASCs) in Tennessee from January 2023 to November 2024. Notably, the outbreak could not be attributed to contaminated water sources, which are typically associated with non-tuberculous mycobacteria (NTM) outbreaks, presenting a unique challenge. METHODS: Outbreak investigation steps included Infection Prevention (IP) assessments, case-control study, environmental sampling, whole genome sequencing, and a healthcare personnel (HCP) exposure questionnaire. RESULTS: IP assessment highlighted several concerns, including no formal facility water management program (WMP), a lack of dedicated IP personnel and certified sterile processing staff, the absence of a formalized system for tracking surgical site infections, and a notable gap in understanding the requirements for reporting diseases. The case-control findings revealed a significant association between the presence of a surgical technologist in the operating room during the procedures and the occurrence of NTM infections, indicated by an odds ratio of 55.77 (95% CI [3.16-985.44]; P = 0.0097). Thirteen clinical isolates collected at one ASC and three additional isolates collected at a second ASC were highly related by whole genome sequencing. CONCLUSION: The study further elucidates valuable insights gained from the outbreak response, including the gaps in surveillance within the ambulatory surgical setting and systematic collection of cultures from environmental sources. It emphasizes the importance of thorough vetting, onboarding, continuing education, and practice monitoring for HCP.

Humans↗

PubMed1980

Application of serological typing to the investigation of outbreaks of Clostridium perfringens food poisoning, 1970-1978.

Serological typing was used as an epidemiological tool in the investigation of 524 outbreaks of Clostridium perfringens food poisoning in the United Kingdom and 37 outbreaks in other countries. Five thousand five hundred and fifty-four (77%) of 7245 strains of C. perfringens associated with the 561 outbreaks were typable with the 75 Food Hygiene Laboratory antisera; in 354 (63%) of these outbreaks a specific serotype was established as being responsible for the outbreak. An assessment is made of the ability of two additional sets of antisera, prepared against 34 American and 34 Japanese strains of C. perfringens, to increase the number of strains which can be typed. The extent of cross-reaction between the three sets of antisera was determined and the results are discussed in relation to the source and history of the type strains.

Clostridium Infections↗

PubMed1996

Recurrent outbreaks of Salmonella Enteritidis infections in a Texas restaurant: phage type 4 arrives in the United States.

In recent years infection caused by Salmonella serotype Enteritidis (SE) phage type 4 has spread through Europe but has been uncommon in the USA. The first recognized outbreak of this strain in the USA occurred in a Chinese restaurant in EI Paso, Texas, in April 1993; no source was identified. In September 1993, a second outbreak caused by SE phage type 4 was associated with the same restaurant. To determine the cause of the second outbreak, we compared food exposures of the 19 patients with that of two control groups. Egg rolls were the only item significantly associated with illness in both analyses (first control group: odds ratio [OR] 8.2, 95% confidence interval [CI] 2.3-31.6; second control group: OR 13.1, 95% CI 2.1-97.0). Retrospective analysis of the April outbreak also implicated egg rolls (OR 32.4, 95% CI 9.1-126.6). Egg roll batter was made from pooled shell eggs and was left at room temperature throughout the day. These two outbreaks of SE phage type 4 likely could have been prevented by using pasteurized eggs and safe food preparation practices.

Adolescent↗