Active Surveillance for Influenza Reduces but Does Not Eliminate Hospital Exposure to Patients With Influenza.

OBJECTIVE To describe the frequency, characteristics, and exposure associated with influenza in hospitalized patients in a Toronto hospital DESIGN/METHOD Prospective data collected for consenting patients with laboratory-confirmed influenza and a retrospective review of infection control charts for roommates of cases over 3 influenza seasons RESULTS Of the 661 patients with influenza (age range: 1 week-103 years), 557 were placed on additional precautions upon admission. Of 104 with symptoms detected after admission, 57 cases were community onset and 47 were nosocomial (10 nosocomial were part of outbreaks). A total of 78 cases were detected after admission exposing 143 roommates. Among roommates tested for influenza after exposure, no roommates of community-onset cases and 2 of 16 roommates of nosocomial cases were diagnosed with influenza. Of 637 influenza-infected patients, 25% and 57% met influenza-like illness definitions from the Public Health Agency of Canada (PHAC) and Centers for Disease Control and Prevention (CDC), respectively, and 70.3% met the Provincial Infectious Diseases Advisory Committee (PIDAC) febrile respiratory illness definition. Among the 56 patients with community-onset influenza detected after admission, only 13%, 23%, and 34%, met PHAC, CDC, and PIDAC classifications, respectively. CONCLUSIONS In a setting with extensive screening and testing for influenza, 1 in 6 patients with influenza was not diagnosed until patients and healthcare workers had been exposed for >24 hours. Only 30% of patients with community-onset influenza detected after admission met the Ontario definition intended to identify cases, hampering efforts to prevent patient and healthcare worker exposures and reinforcing the need for prevention through vaccination. Infect Control Hosp Epidemiol 2017;38:387-392.

Community- and Healthcare-Associated Methicillin-Resistant Staphylococcus aureus Strains: An Investigation Into Household Transmission, Risk Factors, and Environmental Contamination.

OBJECTIVE To measure transmission frequencies and risk factors for household acquisition of community-associated and healthcare-associated (HA-) methicillin-resistant Staphylococcus aureus (MRSA). DESIGN Prospective cohort study from October 4, 2008, through December 3, 2012. SETTING Seven acute care hospitals in or near Toronto, Canada. PARTICIPANTS Total of 99 MRSA-colonized or MRSA-infected case patients and 183 household contacts. METHODS Baseline interviews were conducted, and surveillance cultures were collected monthly for 3 months from household members, pets, and 8 prespecified high-use environmental locations. Isolates underwent pulsed-field gel electrophoresis and staphylococcal cassette chromosome mec typing. RESULTS Overall, of 183 household contacts 89 (49%) were MRSA colonized, with 56 (31%) detected at baseline. MRSA transmission from index case to contacts negative at baseline occurred in 27 (40%) of 68 followed-up households. Strains were identical within households. The transmission risk for HA-MRSA was 39% compared with 40% (P=.95) for community-associated MRSA. HA-MRSA index cases were more likely to be older and not practice infection control measures (P=.002-.03). Household acquisition risk factors included requiring assistance and sharing bath towels (P=.001-.03). Environmental contamination was identified in 78 (79%) of 99 households and was more common in HA-MRSA households. CONCLUSION Household transmission of community-associated and HA-MRSA strains was common and the difference in transmission risk was not statistically significant. Infect Control Hosp Epidemiol 2016;1-7.

A multifaceted prevention program to reduce infection after cesarean section: Interventions assessed using an intensive postdischarge surveillance system.

BACKGROUND: We assessed the effects of the components of a multifaceted and evidence-based caesarean-section surgical site infection (SSI) prevention program on the SSI rate after cesarean section using a postdischarge surveillance (PDS) system. METHODS: Multiple prevention interventions were serially implemented. SSI case finding was undertaken through active inpatient surveillance and intensive PDS using a standardized form at the 6-week postdischarge visit. SSI diagnosis was made using the Centers for Disease Control and Prevention standardized criteria. All cesarean deliveries between July 2007 and December 2012 were included. Changes in SSI rate were analyzed using segmented regression analysis. RESULTS: Nine thousand four hundred forty-two cesarean sections were assessed during the study period. PDS forms were completed for 7,985 women (85%). SSI was detected in 451 cases (5.6%): 91% were superficial, 9% were deep/organ-space infections. The SSI rate decreased incrementally from 8.2% at baseline to 4.1%; significant decreases were observed after optimizing antibiotic prophylaxis timing, using a surgical safety checklist, and enhancing prenatal education to discourage prehospital self-removal of hair. Nonelective surgeries or those undertaken after >12 hours of rupture of membranes had a significantly higher rate compared with those without either risk factor (6.3% vs 3.2%; P < .001). CONCLUSIONS: A multifaceted SSI prevention strategy, with periodic feedback of data, led to a significant reduction in SSI rates after cesarean section.

Prevalence of methicillin-resistant Staphylococcus aureus in skin and soft tissue infections in patients presenting to Canadian emergency departments.

BACKGROUND: Community-associated methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common cause of skin and soft tissue infection (SSTI) worldwide. The prevalence of MRSA in SSTIs across Canada has not been well described. Studies in the United States have shown significant geographic variability in the prevalence of MRSA. This study characterizes the geographic prevalence and microbiology of MRSA in patients presenting to Canadian emergency departments with SSTIs. METHODS: Using a prospective, observational design, we enrolled patients with acute purulent SSTIs presenting to 17 hospital emergency departments and 2 community health centres (spanning 6 Canadian provinces) between July 1, 2008, and April 30, 2009. Eligible patients were those whose wound cultures grew S. aureus. MRSA isolates were characterized by antimicrobial susceptibility testing and pulsed-field gel electrophoresis. All patients were subjected to a structured chart audit, and patients whose wound swabs grew MRSA were contacted by telephone to gather detailed information regarding risk factors for MRSA infection, history of illness, and outcomes. RESULTS: Of the 1,353 S. aureus-positive encounters recorded, 431 (32%) grew MRSA and 922 (68%) wounds grew methicillin-susceptible S. aureus. We observed significant variation in both the prevalence of MRSA (11-100%) and the proportion of community-associated strains of MRSA (0-100%) across our study sites, with a significantly higher prevalence of MRSA in western Canada. INTERPRETATION: MRSA continues to emerge across Canada, and the prevalence of MRSA in SSTIs across Canada is variable and higher than previously expected.

Too close for comfort: screening strategy to detect methicillin-resistant Staphylococcus aureus conversion in exposed roommates.

All 899 roommates exposed to methicillin-resistant Staphylococcus aureus (MRSA) index cases were studied over 57 months. MRSA detection is better at approximately 3 days (50%-55%) or 7 days (56%) after contact has been broken than day 0 (30%). Polymerase chain reaction testing at day 3 performs similarly to culture at day 7. Nasal/rectal screening provides superior detection than nasal alone. Those exposed >48 hours are at significantly greater risk of colonization.

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.