Nosocomial outbreak of Streptococcus pneumoniae Spain9V‑ST156‑14 clone in a pulmonary diseases ward

INTRODUCTION Streptococcus pneumoniae (S. pneumoniae) is one of the most common bacterial pathogens in community‑acquired pneumonia. However, nosocomial pneumococcal infections are more and more widely observed.
OBJECTIVES The aim of the study was to analyze nosocomial outbreak in one of the Polish hospitals and to characterize the causative isolates.
PATIENTS AND METHODS Within 10 days, in 6 patients receiving an antimicrobial therapy due to a primary disease, pneumococcal infections of the lower respiratory tract were identified. All patients, except 1 patient with asthma, were hospitalized due to exacerbation of chronic obstructive pulmonary disease (COPD). The isolates were identified by standard methods. The serotypes of S. pneumoniae were determined by the Pneumotest‑Latex kit. The relatedness among isolates was evaluated by restriction fragment length polymorphism followed by pulsed‑field gel electrophoresis (RFLP‑PFGE). Multilocus sequence typing (MLST) was performed for a representative isolate.
RESULTS The outbreak was suspected when characteristic multidrug‑resistant pneumococci were isolated from patients of a single ward. The outbreak was confirmed by molecular typing techniques. All isolates belonged to serotype 14 and shared the RFLP‑PFGE pattern. MLST for a representative isolate revealed that it was a member of the epidemic Spain9V‑ST156 clonal complex.
CONCLUSIONS Timely implementation of infection control measures enabled to eradicate the outbreak. Pneumococcal conjugate vaccine, recently registered for use in adult populations, may have a considerable effect on limiting pneumococcal disease‑associated morbidity and mortality. It is especially important for patients with COPD, a disease entity that constitutes a risk factor for the acquisition of multidrug‑resistant pneumococci.