Risk Factors for SARS Transmission from Patients Requiring Intubation: A Multicentre Investigation in Toronto, Canada

In the 2003 Toronto SARS outbreak, SARS-CoV was transmitted in hospitals despite adherence to infection control procedures. Considerable controversy resulted regarding which procedures and behaviours were associated with the greatest risk of SARS-CoV transmission.A retrospective cohort study was conducted to identify risk factors for transmission of SARS-CoV during intubation from laboratory confirmed SARS patients to HCWs involved in their care. All SARS patients requiring intubation during the Toronto outbreak were identified. All HCWs who provided care to intubated SARS patients during treatment or transportation and who entered a patient room or had direct patient contact from 24 hours before to 4 hours after intubation were eligible for this study. Data was collected on patients by chart review and on HCWs by interviewer-administered questionnaire. Generalized estimating equation (GEE) logistic regression models and classification and regression trees (CART) were used to identify risk factors for SARS transmission. ratio ≤59 (OR = 8.65, p = .001) were associated with increased risk of transmission of SARS-CoV. In CART analyses, the four covariates which explained the greatest amount of variation in SARS-CoV transmission were covariates representing individual patients.Close contact with the airway of severely ill patients and failure of infection control practices to prevent exposure to respiratory secretions were associated with transmission of SARS-CoV. Rates of transmission of SARS-CoV varied widely among patients

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

Parotitis in a Child Infected with Triple-Reassortant Influenza A Virus in Canada in 2007 ▿

Swine H3N2 influenza virus designated A/Ontario/1252/2007 was isolated from a child with parotitis. Diagnosis was confirmed by viral isolation and serological assays. A/Ontario/1252/2007 was related to H3N2 triple reassortants that emerged in swine in the United States in 1998. Three of five tested household members were also seropositive for A/Ontario/1252/2007

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. Key Words: Community-acquired MRSA; Panton-Valentine leukocidin; SCCmec type IV Éclosion nosocomiale de staphylocoque doré méthicillinorésistant associé à la communauté chez des nouveau-nés et des nouvelles accouchées en bonne santé HISTORIQUE : Un staphylocoque doré méthicillinorésistant associé à la communauté (ou CA-MRSA pour community-associated methicillinresistant Staphylococcus aureus) est isolé de plus en plus souvent chez des individus ne présentant aucun facteur de risque prédisposant. Toutefois, ce type de souches a rarement été associé à une éclosion en milieu hospitalier. La présente étude décrit l'enquête entourant une éclosion de CA MRSA survenue dans une unité d'obstétrique/néonatalogie d'un grand hôpital universitaire communautaire de Toronto, Ontario. MÉTHODES : Les spécimens de dépistage et cliniques recueillis chez des mères ayant accouché durant la période de l'éclosion et leur nouveau-né, de même que chez le personnel de l'unité affecté ont été soumis à des analyses microbiologiques. Les compte rendus informatisés des accouchements et les notes des infirmières ont été passés en revue et une étude cas-témoins a été réalisée. RÉSULTATS : L'analyse par électrophorèse sur gel en champ pulsé a révélé que 38 bébés et sept mères ont présenté une colonisation et/ou une infection à la même souche de MRSA (liée au MRSA-10 canadien) entre septembre et décembre 2004. Les isolats se sont révélés dotés d'une cassette chromosomique mec du staphylocoque de type IVa et ils étaient positifs à l'endroit du gène de la leucocidine de Panton-Valentine. Aucun travailleur de la santé n'a été associé à lui seul à tous ces cas; par contre, les mères et les nouveau-nés exposés à une infirmière en particulier (infirmière A) étaient près de 23 fois (rapport des cotes 22,7, IC à 95 %, 3,3 à 195,9) plus susceptibles de contracter le MRSA que ceux qui n'avaient pas été en contact avec elle. Le MRSA a été isolé avec succès chez l'infirmière A et dans un prélèvement provenant de la surface d'un téléphone récemment utilisé par l'infirmière A. Les deux isolats correspondaient à l'isolat de la souche associée à l'éclosion identifiée par l'électrophorèse sur gel en champ pulsé. CONCLUSION : La première éclosion nosocomiale de CA-MRSA chez des nouveau-nés et des nouvelles accouchées en bonne santé au Canada est décrite ici. La lutte efficace contre la transmission soutenue du MRSA dans un établissement peut nécessiter une identification, un traitement et une surveillance rapides du personnel colonisé et/ou infecté. T he transmission of methicillin-resistant Staphylococcus aureus (MRSA) in the health care setting has been frequently documented among high-risk populations. In pediatric patients, risk factors for MRSA colonization or infection include prior hospitalization, premature birth or low birth weight, chronic underlying diseases, prolonged or recurrent exposure to antibiotics, and invasive or surgical procedures (1,2). Newborns, especially those born prematurely and those requiring specialized care, are thus highly susceptible to infection with this organism; for this reason, outbreaks of MRSA have routinely been reported in neonatal intensive care units (NICUs) (3-6). In recent years, however, MRSA has emerged as a source of skin and soft tissue infections in the community, and has increasingly been isolated from children and adults with no predisposing risk factors. Evidence suggests that these communityassociated strains of MRSA (CA-MRSA) are genetically distinct from those associated with the health care setting and demonstrate different antibiotic susceptibilities (7-9). Transmission of CA-MRSA has been described in several community settings, such as child care centres (10), military bases (11), prisons (12,13) and school sports teams (14). Adding complexity to the epidemiology of MRSA, several reports have now documented the transmission of CA-MRSA in the hospital setting among patients with and without traditional risk factors for MRSA acquisition (15-22). However, nosocomial outbreaks of CA-MRSA have rarely involved healthy newborns and postpartum women (23-25). In October 2004, an outbreak of CA-MRSA was identified among healthy discharged neonates and their mothers at a large community teaching hospital in Toronto, Ontario. Those affected had no known predisposing risk factors, and most were hospitalized for less than 24 h. The present article describes the investigation to determine the scope and source of this outbreak. METHODS Setting Integrating four services on one floor, the maternal-newborn unit includes fetal assessment, labour and delivery, and postpartum and neonatal intensive care (24-bed level II NICU). Over 5000 deliveries are performed annually by family physicians, obstetricians and midwives, with assistance from the labour and delivery unit nursing staff. Following delivery, mothers are admitted to the postpartum unit; newborns are also admitted unless they require care in the NICU. Barring complications, both may be discharged home within 24 h to 72 h, depending on the method of delivery (eg, vaginal or caesarean). Case finding Mothers and babies: On October 13, 2004, the Infection Prevention and Control program (North York General Hospital, Toronto, Ontario) became aware of six babies with laboratoryconfirmed MRSA infection who had been born at the hospital between September 30 and October 7, 2004, and were routinely discharged. All mothers who delivered during this time were contacted and advised to bring their newborns into the hospital to be screened for MRSA colonization or infection. Each infant was assessed by a physician and had screening specimens collected from three sites (eg, nasal, rectal and umbilical). When three additional infants and two mothers who had delivered after October 7 were identified as having been infected or colonized with MRSA, the screening clinics were expanded to include all mothers and babies delivered at the hospital between September 29 and October 22, 2004. As a result of ongoing media reports of the outbreak, several mothers and babies who had delivered before September 29 selfreported to the hospital. All mothers who gave birth between September 1 and September 28, 2004, were subsequently sent a letter advising them to seek medical attention if they had reason to suspect staphylococcal infection in themselves or their newborns. Additional case finding efforts included enhanced surveillance for skin and soft tissue infections in neonates admitted to the inpatient pediatric unit and weekly screening of babies admitted to the NICU. Infection control professionals and physicians at other local hospitals, as well as pediatricians in the community, were alerted to monitor for infants with symptoms consistent with staphylococcal infections, and to report such cases to the hospital. Because the source of the outbreak was not definitively established at the end of October 2004, a sentinel surveillance system was implemented. Selected obstetricians and pediatricians affiliated with the hospital were asked to obtain screening specimens from all the newborns seen in their offices (usually three to four days postdischarge). This enhanced surveillance by sentinel physicians was discontinued on November 15, 2004, in favour of routine laboratory-based surveillance. Cases were defined initially as any mother or baby with delivery between September 29 and October 22, 2004, with a positive MRSA culture matching the outbreak strain (as determined by pulsed-field gel electrophoresis [PFGE]) isolated from either a screening specimen (colonized case) or a clinical specimen (infected case). This definition was later expanded to encompass both phases of the outbreak from September 1 to December 31, 2004. Secondary cases were defined as any mother or baby who either shared a room with an infected or colonized case or was admitted into a room previously occupied by a case within the previous 12 h. Staff: After the initial cases were identified, the medical charts of the MRSA-positive newborns and their mothers were reviewed for staff contacts. Occupational Health was notified, and health care workers who had direct contact with the infected patients were screened. As additional cases were discovered, screening was recommended for all staff on the maternal-newborn unit and included the collection of both nasal and rectal swabs. Any employee with symptoms consistent with staphylococcal infection was assessed by Occupational Health, tested for culture, prescribed antibiotic treatment, and advised to remain off work until the infection resolved. Laboratory testing All screening and clinical specimens collected from mothers, newborn infants and hospital staff were submitted for microbiological testing to the Shared Hospital Laboratory in Scarborough, Ontario. All specimens were processed according to standard microbiological methodology. MRSA isolates were forwarded to a tertiary care hospital laboratory for fingerprinting using Sma-I digested PFGE. Representative isolates were tested for the PantonValentine leukocidin (PVL) and staphylococcal protein A (spa) genes, as well as for staphylococcal chromosome cassette mec (SCCmec) typing. samples were collected because all units had undergone enhanced environmental cleaning the previous day. Risk factor assessment Computerized delivery logs, which were obtained for all births recorded during the study period, provided information on the mother's gestational age, date and time of birth, the infant's sex and birth weight, type of delivery, method of membrane rupture, use and type of anaesthesia, and the names of all health care workers in attendance at delivery. Computerized nursing notes for each of the mothers documented details on all nursing and/or medical interventions (eg, positioning, administration of fluids, medications, etc) experienced during their stay in the labour and delivery unit. Finally, paper-based medical charts were retrieved from the postpartum unit for all confirmed MRSA cases, and inpatient medical records were obtained for the mothers of all infected or colonized babies. An epidemic curve was generated for mothers and babies with MRSA colonization and infection by date of delivery. A spot map was also plotted with the patients' postpartum room assignments. Statistical tests of significance were performed for all risk factor variables (eg, χ 2 test for categorical variables and Student's t test for continuous variables). Case control study A case-control study was conducted to identify potential risk factors associated with the acquisition of MRSA infection or colonization. All of the mother and baby pairs who went through delivery between September 29 and October 11, 2004, and were screened for MRSA were considered eligible. Cases were defined as any mother and baby pairs in which at least one person met the case definition for MRSA infection or colonization. Individuals meeting the definition of a secondary case were excluded from the analysis, as were those whose PFGE pattern results were either unavailable or not related to the outbreak strain. All of the noncases (eg, both the mother and baby were screened as negative for MRSA) were included as controls. The main exposure of interest was hypothesized to be direct contact with an infected or colonized health care worker. For each of the cases and controls, computerized delivery logs and nursing notes were reviewed, and the names of all health care workers with documented contact with the patient were extracted. Odds ratios (ORs) and 95% CIs were calculated for each health care worker based on three levels of exposure: presence at delivery only, documented contact in the nursing notes only (eg, provided nursing care in the labour and delivery unit), and both the presence at delivery and documentation in the nursing notes. Additional variables of interest included mother's gestational age, date and time of birth, the infant's sex and birth weight, type of delivery, method of membrane rupture, and the use and type of anaesthesia. Statistical tests of significance were performed for all risk factor variables (eg, χ 2 test for categorical variables, Student's t test for continuous variables and 95% CIs)