BACKGROUND: In October 2016, an infectious disease clinician at an acute care hospital in New Hampshire reported 4 cases of invasive Group A Streptococcus (GAS) infection to the New Hampshire Division of Public Health Services (DPHS). The 4 patients were admitted within 4 days of each other and blood cultures from each identified Streptococcus pyogenes. Initial interviews revealed that all were persons who inject drugs (PWID).
METHODS: DPHS initiated an investigation using a standardized questionnaire and data collection instrument for case finding to assess risk factors for infection. To identify additional cases, DPHS reviewed GAS cases reported since July 2016 and sent a Health Alert Network message to healthcare providers. A press release was issued to notify PWID of the outbreak. Isolates obtained from the first four cases were analyzed by Pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS) using standard procedures.
RESULTS: Retrospective review of disease reports and outreach to providers identified 7 additional cases of invasive GAS among PWID. Seven (67%) patients were diagnosed with cellulitis, 10 (90%) with bacteremia, and 6 (55%) with sepsis. Two (18%) cases had pneumonia and 5 (55%) experienced respiratory symptoms including cough and hemoptysis. Nine (82%) cases experienced disease onset during October; only 2 cases were identified with earlier onset. Six (55%) cases reported homelessness. Ten (90%) cases were also seropositive for hepatitis C virus infection; including three (30.0%) with a new diagnosis. Specimens for 8 of 11 cases were obtained for microbiology drug susceptibility testing (DST) to evaluate for GAS strain relatedness. We identified three different antibiotic susceptibility patterns, with 5 isolates demonstrating pan-sensitive antibiotic susceptibilities. Specimens from the 4 initial cases were collected for molecular characterization. Pulsed-field gel electrophoresis and whole-genome sequencing confirmed a common strain of S. pyogenes among 3 patients residing in the same city, 2 of which also had a social connection.
CONCLUSIONS: This outbreak report highlights a lesser known yet important life threatening bacterial complication of injecting drugs. NH has been disproportionately impacted by the narcotic epidemic and our clinicians need urgent education and awareness of this complication. Invasive GAS is not a nationally notifiable condition and outbreaks affecting PWID may go unrecognized in jurisdictions that do not track these infections. Strong partnerships between public health departments and healthcare providers can facilitate identification of unique clusters and creative outreach strategies to minimize transmission and ultimately connect PWID to effective addiction services.