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

Marc G. Romney () 0 1 2 4 6 7 8 Mark W. Hull 0 2 3 6 7 8 R eka Gustafson 0 1 2 5 6 7 8 Jat Sandhu 0 2 5 6 7 8 Sylvie Champagne 0 1 2 4 6 7 8 Titus Wong 0 1 2 6 7 8 Anouf Nematallah 0 1 2 6 7 8 Sara Forsting 0 2 5 6 7 8 Patricia Daly 0 1 2 5 6 7 8 0 Vancouver is home to a significant population of 1 Faculty of Medicine, University of British Columbia 2 have occurred in closed communities with high levels 3 Medicine, St. Paul's Hospital, Providence Health Care 4 Pathology and Laboratory Medicine 5 Communicable Disease Control, Vancouver Coastal Health , Vancouver, Canada 6 median income in the DTES is !30% that of the city's 7 inner-city poor who reside in a neighborhood known 8 Figure 2. A, Serotype distribution for Streptococcus pneumoniae iso- lates recovered from patients with invasive pneumococcal disease at St. Paul's Hospital ( Vancouver, Canada) , 1 January 2002-31 July 2006. B, Serotype distribution for S. pneumoniae isolates recovered from patients with invasive pneumococcal disease at St. Paul's Hospital , 1 August 2006- 31 July 2007 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. Paul's 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. Despite the introduction of antibiotics in the 1940s, level [1-6]. These community-based outbreaks of IPD and more recently, the development of polysaccharide and conjugate pneumococcal vaccines, Streptococcus pneumoniae remains a leading cause of morbidity and mortality worldwide. Most disease due to S. pneumoniae is sporadic, and outbreaks of invasive pneumococcal as the Downtown Eastside (DTES). Approximately disease (IPD) are rare. Of outbreaks reported in the 17,000 individuals live in the DTES, which includes antibiotic era, most have arisen in institutional settings, and smaller numbers have occurred at the community - Outbreak investigation and control. St. Pauls Hospital (SPH) is a tertiary-care facility that serves Vancouvers DTES. In August 2006, the SPH medical microbiology laboratory detected an increase in the number blood cultures positive for S. pneumoniae. Concurrently, an increase in the number of patients presenting with pneumonia and sepsis was reported by hospital physicians. Prospective laboratory-based surveillance for IPD was initiated in September 2006. To ensure data completeness, retrospective microbiologic data for the period January 2002August 2006 were extracted from the SPH laboratory information system. A case of IPD was defined as the isolation of S. pneumoniae from a sterile site, such as blood or CSF. Cases were identified daily by laboratory physicians. Cases of IPD were reported to public health officials at Vancouver Coastal Health, leading to a region-wide outbreak investigation. Vancouver Coastal Health covers a population of 11 million people in 17 municipalities, including the city of Vancouver. In response to the outbreak, case follow-up was initiated, and an attempt was made to interview each involved patient. Additional information was obtained from hospital charts, primary care clinics, and public health records. Enhanced regional surveillance for IPD continued for a period of 12 months after identification of the index case. To control the outbreak, a vaccination campaign using the 23-valent polysaccharide pneumococcal vaccine was initiated in the DTES, modelled on previous outreach campaigns in this neighborhood. S. pneumoniae serotype 5 is included among the strains covered by the 23-valent polysaccharide pneumococcal vaccine. More than 6000 doses of vaccine were administered from 6 November through 22 December 2006. Microbiological methods. Blood samples were collected and cultures were incubated using automated blood culture systems. Blood and fluid cultures positive for gram-positive diplococci were subcultured to 5% sheeps blood agar. S. pneumoniae was identified using the optochin susceptibility test and the Phadebact Pneumococcus Test (Bactus AB). If bacteria that resembled S. pneumoniae failed to grow on subculture at the SPH medical microbiology laboratory, a molecular probe for S. pneumoniae (AccuProbe Streptococcus pneumoniae Culture Identification Test; GenProbe) was used, and patients with positive results were considered to be case patients. For the rapid identification of S. pneumoniae in positive blood cultures at SPH, probes for S. pneumoniae were used directly on blood culture broths [12]. Susceptibility testing was performed according to Clinical and Laboratory Standards Institute methodology. MIC testing for penicillin, ceftriaxone, and cefotaxime was routinely performed using the E-test (AB Biodisk). Moxifloxacin susceptibility testing was performed using disk diffusion. All S. pneumoniae isolates recovered from sterile sites were forwarded to the British Columbia Centre for Disease Control (Vancouver, Canada) and the Canadian National Centre for Streptococcus (Edmonton, Canada) for serotyping. In December 2006, limited pneumococcal serotyping was implemented at SPH using the Pneumotest-Latex test agglutination test pools A and S (Statens Serum Institute). All serotype results for patients who presented to SPH with IPD were reviewed, dating back to January 2002. Epidemiological and statistical methods. To identify clinical and sociodemographic variables associated with the development o (...truncated)