Sylvie Champagne

The Changing Age and Seasonal Profile of Pertussis in Canada

During the postvaccine era in Canada, most cases of pertussis have been reported in children <5 years of age, with the highest incidence, morbidity, and mortality in infants <1 year old. Population-based data, with very high laboratory confirmation rates and hospital separation and mortality statistics, chronicle the changing age and seasonal profile associated with pertussis over recent successive outbreaks in British Columbia, Canada. A large outbreak during 2000 highlights 2 important changes to the postvaccine profile. For the first time in Canada, the incidence of pertussis among preteens and teens surpassed that of all other age groups. At the same time, a decreasing incidence of pertussis among infants and preschool children highlights reduced susceptibility in the very young. Recent changes in the childhood immunization program (including introduction of an acellular pertussis vaccine), waning immunity, and changes in laboratory methods are considered in explaining these 2 simultaneous but divergent trends in the pertussis profile.

Outbreak of cyclosporiasis in British Columbia associated with imported Thai basil

Sporadic outbreaks of cyclosporiasis, a common cause of protracted diarrhoea in underdeveloped countries, are often undetected and undiagnosed in industrial countries. In May 2001, an outbreak of Cyclospora cayetanensis gastroenteritis was identified in British Columbia, Canada, with 17 reported cases. We conducted a case-control study involving 12 out of the 17 reported and confirmed case patients. Eleven (92%) of the patients had consumed Thai basil, an essential ingredient in Vietnamese cuisine, compared to 3 out of 16 (19%) of the control patients (P = 0.003). Trace-back investigations implicated Thai basil imported via the United States as the vehicle for this outbreak. This is the first documented sporadic outbreak of cyclosporiasis linked to Thai basil in Canada, and the first outbreak of cyclosporiasis identified in an ethnic immigrant population. This outbreak provides the opportunity to increase our understanding of this emerging pathogen and improve on our prevention and control for future outbreaks.

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.

Neisseria meningitidis Carriage during an Outbreak of Serogroup C Disease

During 2001, an outbreak of serogroup C meningococcal disease led to immunization of individuals aged 13-29 years in Abbotsford, British Columbia, Canada. This study addresses the distribution of Neisseria meningitidis carriage in this population and the implications of that distribution for the targeting of the immunization campaign. Pharyngeal swabs were obtained at immunization from 2004 people. Colonies were identified and serogrouped using standard agglutination methods and by PCR. Isolates were characterized using pulsed-field gel electrophoresis (PFGE). The prevalence of N. meningitidis carriage was 153 carriers per 2004 subjects (7.6%; 95% confidence interval, 6.5%-8.9%). Only 6 (4%) of the isolates from these carriers were found to be serogroup C by agglutination or PCR testing, and all of these were from individuals within the age group targeted for immunization. Only 1 of these 6 isolates was found to be identical to the outbreak strain by PFGE. The observation that a virulent strain is not circulating widely suggests the possibility of low background immunity in the population at risk and emphasizes the importance of vaccination in controlling epidemic group C meningococcal disease.

mcr-1–Positive Colistin-Resistant Escherichia coli in Traveler Returning to Canada from China

To the Editor: A 61-year-old man underwent transurethral prostate resection in Vancouver, British Columbia, in January 2016. On postoperative day 1, he was febrile (39.1°C) and had leukocytosis (12.7 × 109 cells/L). Blood and urine cultures were ordered on postoperative day 2, and ceftriaxone was started. On postoperative day 3, urine culture grew Escherichia coli (>100 million CFU/L). Susceptibility testing (VITEK2, bioMerieux, Quebec, Canada) indicated a possible extended-spectrum β-lactamase producer and showed resistance to ampicillin, cefazolin, ceftriaxone, gentamicin, ciprofloxacin, and trimethoprim/sulfamethoxazole; intermediate resistance to tobramycin; and susceptibility to amoxicillin/clavulanate, piperacillin/tazobactam, ertapenem, meropenem, and nitrofurantoin. Treatment was switched to amoxicillin/clavulanate. The urinary catheter was removed 48 hours later. The patient was discharged on postoperative day 5 and completed 14 days of oral amoxicillin/clavulanate. Blood cultures were negative after 7 days’ incubation.

Evaluation of Skin Antisepsis Prior to Blood Culture in Neonates

In our Intensive Care Nursery, coagulase-negative staphylococcus is the most frequent blood culture isolate. As skin antisepsis is critical in preventing blood culture contamination, we examined the efficacy of the chlorhexidine tincture (CH) used in our nursery for this purpose. Staphylococcus epidermidis colonized the forearms of 88% of infants tested, in a mean density of 10(4) organisms/cm2. Following a 60-second application of CH (0.5% in 70% ethanol), bacterial growth from forearm skin remained abundant in 15/38 infants (39.4%). Cleansing with 70% isopropyl alcohol, followed by CH as above, left abundant residual growth in only 1/37 infants (2.7%) (P less than 0.001). All 136 S. epidermidis tested were susceptible to CH (MIC less than 5 micrograms/ml) and 14 of 15 exposed to CH 0.02% were rapidly killed (greater than or equal to 98% fall in viable counts within 90 sec). We conclude that two-phase antisepsis using isopropanol followed by CH is a more effective preparation for blood culture in neonates than is CH alone.

Development and Validation of a Pneumocystis jirovecii Real-time Polymerase Chain Reaction Assay for Diagnosis of Pneumocystis Pneumonia

Pneumocystis pneumonia is caused by Pneumocystis jirovecii, an opportunistic fungal pathogen. Presently, many clinical microbiology laboratories rely on direct microscopic detection of P jirovecii. The validation, and clinical and laboratory development of a qualitative P jirovecii real-time polymerase chain reaction assay for the rapid detection of Pneumocystis pneumonia is discussed by the authors. In addition, this new technique is compared with the existing gold-standard immunofluorescence assay.

Epidemiologic and Genotypic Review of Carbapenemase-Producing Organisms in British Columbia, Canada, between 2008 and 2014

ABSTRACT Carbapenemase-producing organisms (CPOs) are a serious emerging problem for health care facilities worldwide. Owing to their resistance to most antimicrobial therapies, CPOs are difficult to treat and pose a challenge for infection prevention and control. Since 2010, lab-based surveillance for CPOs and PCR-based testing were implemented in British Columbia (BC), Canada. A review of CPOs in BC from 2008 to March 2014 was done to characterize the resistance mechanisms and possible clonal strain transmission and to compare pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and plasmid restriction fragment length polymorphism (RFLP) as molecular typing tools. During this study period, a total of 177 CPO cases were identified. Patient demographics and travel history were reviewed, and a descriptive analysis was carried out. PFGE profiles, MLST, and plasmid RFLP analysis for a subset of Escherichia coli, Klebsiella pneumoniae, and Enterobacter species isolates were obtained and analyzed. Our findings demonstrate that CPOs have been increasing in number in BC over time, from 1 isolate/year retrospectively identified in 2008 and 2009 to 82 isolates in 2013 and 30 isolates in the first quarter of 2014. Overall, K. pneumoniae isolates lack clonality, although some seemingly related clusters have been found. Plasmid analysis showed evidence of the spread of plasmids carrying carbapenemase-encoding genes between the examined isolates. Analysis of Enterobacter cloacae isolates revealed a more clonal nature of these CPOs in BC. The presence of related clusters provides evidence of interpatient organism transmission both within and between institutions. Although in our study, NDM-harboring E. cloacae isolates appeared to spread clonally, the spread of carbapenem resistance in K. pneumoniae seems to be plasmid mediated.

Shigella flexneri serotype 1 infections in men who have sex with men in Vancouver, Canada.

Outbreaks of shigellosis have been documented in men who have sex with men (MSM), associated with interpersonal transmission and underlying HIV infection. We observed a rise in Shigella flexneri isolates identified in a downtown tertiary‐care hospital laboratory located within the city centre community health area (CHA‐1) of Vancouver, Canada. The objectives of this study were to evaluate clinical outcomes of shigellosis cases among MSM admitted to hospital and to evaluate trends in Shigella cases within Vancouver, Canada.

Screening for methicillin-resistant Staphylococcus aureus (MRSA) in community-recruited injection drug users: are throat swabs necessary?

We examined and described colonization of MRSA in the anterior nares and throat from 184 community-recruited injection drug users. Thirty-seven (20%) were positive for MRSA: most (34, 92%) were carriers in the nares; while only three (8%) were carriers detected by throat swabs alone. The majority (29, 78%) of MRSA isolates were PVL positive.