Commentary on the adoption of a test-based versus syndromic-based approach to outbreak declaration and management in hospital and institutional settings.

At present, Ontario, like most other jurisdictions in Canada, uses a syndromic-based surveillance definition for acute respiratory infection (ARI) outbreaks in institutions and public hospitals. Confirmed outbreaks are defined as either two or more ARIs in 48 hours with any common epidemiological link and at least one that is laboratory-confirmed; or three cases of ARIs occurring within 48 hours with any common epidemiological link, and not necessarily with lab confirmation. However, with the adoption of broader test-based approaches for sick patients/residents throughout the pandemic, new challenges have surfaced regarding the declaration and management of ARI outbreaks with a variety of scenarios in respiratory testing results. Decisions, including the determination of epidemiological linkage when there are discordant/negative test results, have become more complicated with the addition of virus-specific test results for every sick individual. The ARI outbreak case definition and management guidance was updated in 2018. The purpose of this commentary is to highlight epidemiological trends in ARI outbreaks in Ontario over the 2022-2023 season compared to the 2018-2019 and 2019-2020 pre-pandemic seasons. This is followed by a discussion around some of the benefits and challenges of implementing a test-based versus syndromic-based approach to ARI outbreaks.

A nosocomial outbreak of community-associated methicillin-resistant Staphylococcus aureus among healthy newborns and postpartum mothers.

BACKGROUND: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increasingly been isolated from individuals with no predisposing risk factors; however, such strains have rarely been linked to outbreaks in the hospital setting. The present study describes the investigation of an outbreak of CA-MRSA that occurred in the maternal-newborn unit of a large community teaching hospital in Toronto, Ontario. METHODS: Screening and clinical specimens collected from mothers and newborns delivered during the outbreak period, as well as from staff on the affected unit, were submitted for microbiological testing. Computerized delivery logs and nursing notes were reviewed, and a case control study was conducted. RESULTS: Analysis by pulsed-field gel electrophoresis revealed 38 babies and seven mothers with MRSA colonization and/or infection by the same unique strain (Canadian MRSA-10-related) from September to December 2004. Isolates were characterized as having the staphylococcal chromosome cassette mec type IVa and were positive for the Panton-Valentine leukocidin gene. No one health care worker was associated with all cases; however, mothers and newborns exposed to one particular nurse (Nurse A) were almost 23 times (odds ratio 22.7, 95% CI 3.3 to 195.9) more likely to acquire MRSA than those with no such contact. MRSA was successfully isolated from Nurse A and from an environmental swab of a telephone recently used by Nurse A; both isolates matched the pulsed-field gel electrophoresis pattern of the outbreak strain. CONCLUSION: The first nosocomial outbreak of CA-MRSA among healthy newborns and postpartum mothers in Canada is described. Effective control of sustained MRSA transmission within an institution may require prompt identification, treatment and monitoring of colonized and/or infected staff.

Outbreak of acupuncture-associated cutaneous Mycobacterium abscessus infections.

BACKGROUND: Cutaneous atypical mycobacterial infections have been increasingly described in association with cosmetic and alternative procedures. OBJECTIVE: We report an outbreak of acupuncture-associated mycobacteriosis. Between April and December 2002, 32 patients developed cutaneous mycobacteriosis after visiting an acupuncture practice in Toronto, Canada. RESULTS: Of 23 patients whose lesions were biopsied, 6 (26.1%) had culture-confirmed infection with Mycobacterium abscessus. These isolates were genetically indistinguishable by amplified fragment length polymorphism. The median incubation period was 1 month. Of 24 patients for whom clinical information was available, 23 (95.8%) had resolution of their infection. All patients developed residual scarring or hyperpigmentation. CONCLUSION: Nontuberculous mycobacteria should be recognized as an emerging, but preventable, cause of acupuncture-associated infections.

Late recognition of SARS in nosocomial outbreak, Toronto.

Late recognition of severe acute respiratory syndrome (SARS) was associated with no known SARS contact, hospitalization before the nosocomial outbreak was recognized, symptom onset while hospitalized, wards with SARS clusters, and postoperative status. SARS is difficult to recognize in hospitalized patients with a variety of underlying conditions in the absence of epidemiologic links.

Nosocomial transmission of congenital tuberculosis in a neonatal intensive care unit.

Congenital tuberculosis is uncommon, and nosocomial transmission from a congenitally infected infant to another infant has not been reported in the English literature. We report an investigation of 2 infants with tuberculosis who were cared for in the same neonatal intensive care unit. Isolates from both infants were genetically indistinguishable. Transmission between the 2 infants was likely due to contaminated respiratory equipment.

Public health measures to control the spread of the severe acute respiratory syndrome during the outbreak in Toronto.

BACKGROUND: Toronto was the site of North America's largest outbreak of the severe acute respiratory syndrome (SARS). An understanding of the patterns of transmission and the effects on public health in relation to control measures that were taken will help health officials prepare for any future outbreaks. METHODS: We analyzed SARS case, quarantine, and hotline records in relation to control measures. The two phases of the outbreak were compared. RESULTS: Toronto Public Health investigated 2132 potential cases of SARS, identified 23,103 contacts of SARS patients as requiring quarantine, and logged 316,615 calls on its SARS hotline. In Toronto, 225 residents met the case definition of SARS, and all but 3 travel-related cases were linked to the index patient, from Hong Kong. SARS spread to 11 (58 percent) of Toronto's acute care hospitals. Unrecognized SARS among in-patients with underlying illness caused a resurgence, or a second phase, of the outbreak, which was finally controlled through active surveillance of hospitalized patients. In response to the control measures of Toronto Public Health, the number of persons who were exposed to SARS in nonhospital and nonhousehold settings dropped from 20 (13 percent) before the control measures were instituted (phase 1) to 0 afterward (phase 2). The number of patients who were exposed while in a hospital ward rose from 25 (17 percent) in phase 1 to 68 (88 percent) in phase 2, and the number exposed while in the intensive care unit dropped from 13 (9 percent) in phase 1 to 0 in phase 2. Community spread (the length of the chains of transmission outside of hospital settings) was significantly reduced in phase 2 of the outbreak (P<0.001). CONCLUSIONS: The transmission of SARS in Toronto was limited primarily to hospitals and to households that had had contact with patients. For every case of SARS, health authorities should expect to quarantine up to 100 contacts of the patients and to investigate 8 possible cases. During an outbreak, active in-hospital surveillance for SARS-like illnesses and heightened infection-control measures are essential.