Nontoxigenic Highly Pathogenic Clone of Corynebacterium diphtheriae, Poland, 2004–2012

Aleksandra A. Zasada

Author affiliation: National Institute of Public Health–National Institute of Hygiene, Warsaw, Poland

Abstract

Twenty-five cases of nontoxigenic Corynebacterium diphtheriae infection were recorded in Poland during 2004–2012, of which 18 were invasive. Alcoholism, homelessness, hepatic cirrhosis, and dental caries were predisposing factors for infection. However, for 17% of cases, no concomitant diseases or predisposing factors were found.

Corynebacterium diphtheriae is the causative agent of diphtheria. Its toxin is considered the major virulence factor. Since introduction of vaccine against the diphtheria toxin in the 1940s, infections caused by toxigenic corynebacteria have been well controlled in industrialized countries that have high coverage rates of childhood vaccination with 3 doses of diphtheria-tetanus-pertussis vaccine (1). Nevertheless, emergence of nontoxigenic C. diphtheriae infections has been reported in some of these countries.
In line with other European countries, Poland routinely vaccinates against diphtheria (Technical Appendix

[PDF - 135 KB - 2 pages]). According to data from the World Health Organization, > 95% of children in Poland are fully vaccinated against diphtheria. The last diphtheria case was recorded there in 2000 (http://www.who.int/immunization_monitoring/data/incidence_series.xls

).
The absence of diphtheria during the past 13 years suggests that the high vaccination coverage rates in Poland protect against diphtheria. In 2004, the first case of sepsis caused by nontoxigenic C. diphtheriae was recorded (2). Other cases were recorded in 2006, and since 2007, several cases of C. diphtheriae invasive infections have been recorded every year (Table 1). In addition, local infections—usually wound infections—caused by nontoxigenic C. diphtheriae were recorded (Table 2). A total of 25 nontoxigenic C. diphtheriae infections were recorded in Poland in 2004–2012, of which 18 were invasive infections.

The Study

All patients were admitted to local hospitals and clinical samples for microbiological investigations were sent to the nearest laboratories. C. diphtheriae isolates were sent to National Institute of Public Health–National Institute of Hygiene for confirmation and toxigenicity testing, biotyping, pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and ribotyping. Case classification and microbiological methods used are presented in the Technical Appendix

[PDF - 135 KB - 2 pages]. Data collected for epidemiologic analysis included location; type of infection; year of presentation; and patient age, sex, concomitant diseases, socioeconomic status, and intravenous drug use (IVDU).