Titus Wong

Large Community Outbreak of Streptococcus pneumoniae Serotype 5 Invasive Infection in an Impoverished, Urban Population

BACKGROUND Streptococcus pneumoniae is a common cause of sporadic invasive infections, but outbreaks of invasive pneumococcal disease are infrequent. In August 2006, a sudden increase in the number of patients presenting with invasive pneumococcal disease was noted at St. Pauls Hospital (Vancouver, Canada). Most patients with severe disease resided in an area referred to as the Downtown Eastside, a neighborhood known for its high rates of poverty and illicit drug use. METHODS Prospective, laboratory-based surveillance for invasive pneumococcal disease was initiated, including on-site serotyping of S. pneumoniae isolates. A vaccination campaign using 23-valent polysaccharide pneumococcal vaccine was launched in the Downtown Eastside. Multiple logistic regression was used to examine the association of sociodemographic variables and medical risk factors with S. pneumoniae serotype status. RESULTS A single S. pneumoniae serotype (serotype 5) was responsible for 78% of invasive pneumococcal disease cases (137 of 175 cases) during the outbreak period of August 2006-July 2007. The outbreak strain, although fully susceptible to penicillin, caused significant morbidity and placed considerable strain on the acute care system within the Vancouver Coastal Health region. Crack cocaine use was found to be the main independent risk factor associated with invasive pneumococcal disease due to S. pneumoniae serotype 5 (odds ratio, 12.4; 95% confidence interval, 2.22-69.5). CONCLUSIONS A targeted vaccination campaign using polysaccharide pneumococcal vaccine appeared to help control this outbreak. In urban centers with high rates of illicit drug use, vaccination strategies for preventing invasive pneumococcal disease may need to be refined to include individuals who use crack cocaine.

Prediction of pediatric outcome after prenatal diagnosis and expectant antenatal management of congenital cystic adenomatoid malformation.

Objective: To determine whether the congenital cystic adenomatoid malformation (CCAM) volume ratio (CVR) is associated with fetal and postnatal outcome after prenatal diagnosis and antenatal expectant management in a provincial tertiary referral center that does not offer fetal surgery. Methods: Retrospective cohort of 71 consecutive cases of prenatally diagnosed CCAM meeting study criteria (1996–2004). CVR was calculated on the initial ultrasound at the referral center, and associated with hydrops (Fisher’s exact test) and a composite adverse postnatal outcome consisting of death, intubation for respiratory distress, extracorporeal membrane oxygenation, non-elective surgery for symptomatology, or respiratory infection requiring hospital admission (Mann-Whitney test). Results: A CVR >1.6 was significantly associated with hydrops (p = 0.003). In addition, the CVR was significantly associated with the composite adverse postnatal outcome (p = 0.004) at a mean age of follow-up of 41 months (range <1–117 months). For CVR and postnatal outcome, the area-under-the-curve receiver operating characteristic was 0.81 (95% CI 0.69–0.93, p = 0.006), and choosing a CVR cut-off of <0.56, the negative predictive value was 100% (95% CI 0.85–1.00). Conclusion: In a provincial referral center with antenatal expectant management of CCAM, the CVR was associated with hydrops and postnatal outcome, with a CVR <0.56 predictive of good prognosis after birth.

Nasal photodisinfection and chlorhexidine wipes decrease surgical site infections: a historical control study and propensity analysis.

BACKGROUND Pre-operative decolonization therapy (DcTx) using chlorhexidine (CHG) body washes and/or intranasal mupirocin can reduce surgical site infections (SSIs), but compliance is often suboptimal. AIM To assess the effectiveness of immediate DcTx using a novel approach of intranasal antimicrobial photodisinfection therapy (PDT) combined with CHG body wipes for the reduction of SSIs. METHODS Between 1(st) September 2011 and 31(st) August 2012, 3068 elective cardiac, orthopaedic, spinal, vascular, thoracic and neurosurgical patients were treated with CHG in the 24h preceding surgery, and received intranasal PDT in the pre-operative area. SSI surveillance methodology remained unchanged from previous years and patients were followed for one year. Results were compared with those for a four-year historical control group of 12,387 patients as well as those for a concurrent control group of 206 untreated patients. FINDINGS A significant reduction in the SSI rate was observed between treated patients and the historical control group [1.6% vs 2.7%, P = 0.0004, odds ratio (OR) 1.73, 95% confidence interval (CI) 1.2815-2.3453]. This significant reduction was maintained on intent-to-treat analysis (P = 0.021, OR 1.37, 95% CI 1.0476−1.7854) [corrected]. Overall compliance with DcTx was 94%. A 1:4 propensity score analysis of matched treated and untreated patients demonstrated that DcTx reduced the risk of SSIs significantly (P = 0.00026, z = 3.65). CONCLUSION The combination of CHG wipes and PDT immediately before surgery reduced SSIs, achieved excellent compliance, and was easily integrated into the pre-operative routine.

Postdischarge decontamination of MRSA, VRE, and Clostridium difficile isolation rooms using 2 commercially available automated ultraviolet-C–emitting devices

BACKGROUND Two ultraviolet-C (UVC)-emitting devices were evaluated for effectiveness in reducing methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and Clostridium difficile (CD). METHODS Six surfaces in rooms previously occupied by patients with MRSA, VRE, or CD were cultured before and after cleaning and after UVC disinfection. In a parallel laboratory study, MRSA and VRE suspended in trypticase soy broth were inoculated onto stainless steel carriers in triplicate, placed in challenging room areas, subjected to UVC, and subcultured to detect growth. RESULTS Sixty-one rooms and 360 surfaces were assessed. Before cleaning, MRSA was found in 34.4%, VRE was found in 29.5%, and CD was found in 31.8% of rooms. Cleaning reduced MRSA-, VRE-, and CD-contaminated rooms to 27.9%, 29.5%, and 22.7%, respectively (not statistically significant). UVC disinfection further reduced MRSA-, VRE-, and CD-contaminated rooms to 3.3% (P = .0003), 4.9% (P = .0003), and 0% (P = .0736), respectively. Surface colony counts (excluding floors) decreased from 88.0 to 19.6 colony forming units (CFU) (P < .0001) after manual cleaning; UVC disinfection further reduced it to 1.3 CFU (P = .0013). In a multivariable model of the carrier study, the odds of detecting growth in broth suspensions after UVC disinfection were 7 times higher with 1 machine (odds ratio, 6.96; 95% confidence interval, 3.79-13.4) for a given organism, surface, and concentration. CONCLUSIONS UVC devices are effective adjuncts to manual cleaning but vary in their ability to disinfect high concentrations of organisms in the presence of protein.

Comparison of clinical and epidemiological features of Shiga toxin-producing Escherichia coli O157 and non-O157 infections in British Columbia, 2009 to 2011

INTRODUCTION Shiga toxin-producing Escherichia coli (STEC) are major foodborne agents that have the potential to cause severe enteric illnesses and large outbreaks worldwide. Several studies found non-O157 infections to be clinically milder than O157 STEC infections. OBJECTIVE To compare the clinical and epidemiological profiles of O157 and non-O157 STEC human infections in British Columbia (BC). METHODS All STEC cases reported in BC from 2009 to 2011 by four local health authorities were included in the study. Cases were classified according to STEC serotype based on laboratory information. Information was gathered via case interview forms. Data analysis included the χ(2) test and Mann-Whitney test; P<0.05 was considered to be statistically significant. RESULTS A total of 260 STEC cases were reported, including 154 (59.2%) O157 cases, 63 (24.2%) non-O157 cases and 43 (16.5%) STEC cases with no serotype identified. Hospitalization rate was higher and duration of hospitalization was significantly longer for O157 cases compared with non-O157 cases, but other clinical features were not significantly different. Patients with non-O157 infections were significantly more likely to have travelled outside Canada, less likely to report food exposure at social gatherings and more likely to consume bagged greens and cheese. DISCUSSION O157 is the predominant O serotype in BC and appeared to be more clinically severe than non-O157 STEC infections. However, the true incidence and severity of non-O157 remain unknown due to our current inability to detect all non-O157 cases. The present study and the literature suggest the need to identify more predictive virulence factors because serotype does not consistently predict disease severity.

Clostridium difficile Infection in Patients with Inflammatory Bowel Disease

Clostridium difficile infection (CDI) is now the leading cause of nosocomial infection. There has been an upsurge of CDI in patients with inflammatory bowel disease (IBD). IBD patients with CDI have increased morbidity and mortality. The establishment, proliferation, and recurrence of CDI in IBD patients form a complex interplay of microbial, environmental, and host-susceptibility factors. Different risk factors have been found predisposing IBD patients to CDI. Vancomycin performs better than metronidazole in treating IBD patients with CDI. Fecal microbiota transplantation continues to be a very effective therapy. New therapeutic modalities such as vaccinations and bile salts are currently being investigated.

O010: A novel immediate pre-operative decolonization strategy reduces surgical site infections

Pre-operative decolonization therapy (DcTx) using chlorhexidine (CHG) body washes and/or intranasal mupirocin can reduce surgical site infections (SSI) but compliance is often suboptimal. The effectiveness of a novel approach to immediate pre-operative decolonization therapy using intranasal antimicrobial photodisinfection therapy (PDT) and CHG body wipes in reducing SSIs was assessed.

Evaluation of an ultraviolet C light–emitting device for disinfection of electronic devices

BACKGROUND A tabletop-type ultraviolet C (UVC) light-emitting disinfecting device was evaluated for microbiologic effectiveness, safety, usability, and end-user satisfaction. METHODS Three different inoculums of methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter calcoaceticus-baumannii complex strains suspended in both saline and trypticase soy broth were applied onto stainless steel carriers and electronic device surfaces in triplicate and cultured for growth after UVC disinfection. Assessments of functionality and usability were performed by biomedical and human factors engineers. End-user feedback was captured using a standardized in-use survey. RESULTS The 54 stainless steel carriers displayed growth at inoculums as low as 102 colony forming units (CFU) when a quartz dish supplied by the manufacturer was used during UVC exposure. Without the quartz dish, 54 electronic device surfaces displayed no growth for inoculums from 102-104 CFU for all organisms suspended in saline, but lower kill rates (95.7%-100%) for organisms in broth. Several minor safety and usability issues were identified prior to clinical evaluation. In-use evaluation revealed keen user endorsement; however, suboptimal sensitivity of the machines input sensors during sequential object insertion precluded implementation. CONCLUSIONS Optimization of some safety and functionality parameters would improve a conceptually popular and microbiologically effective tabletop UVC disinfecting device.

Reduction in community-onset methicillin-resistant Staphylococcus aureus rates in an urban Canadian hospital setting.

Community-onset methicillin resistant Staphylococcus aureus (CO-MRSA) became a prominent cause of infection in North America in 2003, with a peak in the epidemic noted by multiple groups in the USA between 2005 and 2007. We reviewed rates of MRSA in two hospitals in Vancouver, Canada, to observe changes in epidemiology from 2003 to 2011. Episodes of emergency department (ED) MRSA bacteraemia and wounds were extracted from the laboratory database, with rates calculated per 10,000 ED visits. All cases were assumed to be community onset, as they were diagnosed in the ED. A peak in ED MRSA bacteraemias occurred in 2005, at 7·8/10,000 ED visits. By 2011, rates of ED bacteraemia declined significantly to 3·3/10,000 ED visits (P<or=0·03). MRSA wound rates peaked at 82·2 cases/10,000 ED visits in 2007 with a subsequent significant decline to 34·3 cases in 2011 (P=0·04). We have demonstrated a significant decline in CO-MRSA within our population, consistent with reports from the USA, suggesting a substantial change in the epidemiology of CO-MRSA in certain North American cities.

Polymerase chain reaction assay to detect Clostridium difficile tcdC variants is valuable in characterizing hospital epidemiology

The epidemiology of nosocomial Clostridium difficile infection (CDI), acquired at two hospitals in Vancouver over a one-year period, was reviewed. Cases were analysed by tcdC polymerase chain reaction, with tcdC variants (18 base pair deletion) highly associated with the NAP1 strain. Of the 214 cases identified, 51.9% were caused by these tcdC variants; these cases occurred more frequently in older patients admitted to the community hospital where the strain was endemic. Overall, at least five out of 24 cases classified as recurrences by surveillance definitions were reinfections. Molecular testing allowed identification of major epidemiological differences between the hospitals studied and provided more accurate classification of CDI cases.