Infections caused by toxigenic C. diphtheriae
are rare in the United States because of widespread vaccination, but remain endemic in countries with suboptimal vaccine coverage.
All 16 isolated C. diphtheriae
tested with RT-PCR and ribotyping were Corynebacterium diphtheriae biovar mitis.
The wound culture grew group A Streptococcus, Pseudomonas, and a coryneform isolate (identified as C. diphtheriae
via MALDITOF and confirmed as toxin-producing).
We defined a confirmed case as the occurrence of clinical symptoms consistent with respiratory diphtheria (sore throat; low-grade fever; and an adherent membrane on the pharynx, tonsils, larynx, or nose) in a person who was positive for toxin-producing C. diphtheriae
and a probable case as the occurrence of mild respiratory symptoms or clinical symptoms of respiratory diphtheria in a C.
Previous reports revealed that isolation rates of C. diphtheriae
ranged from 0 to 14.7 per cent (10) but increased from 3 per cent in 1995 to 36 per cent in 2001 (16).
Absence of widespread circulation of toxigenic C. diphtheriae
cannot be ruled out because of living conditions, the population's difficulties in accessing care, frequency of skin infections, and complexity of microbiological analyses of cutaneous samples.
During the 2-year period from July 1, 2013, until June 30, 2015, a total of 136 isolates of C. diphtheriae
were referred to our laboratory for toxin gene screening; these isolates included 2 that were second isolations from patients, 2 and 3 months after the initial specimens were collected.
Specimens were obtained for isolation of C. diphtheriae
and PCR testing; all culture and PCR results were negative.
In the report by Zasada (4), all 3 recommended methods (PFGE, MLST, and ribotyping) were used to genotype 25 nontoxigenic C. diphtheriae
isolates from Poland.
(+.)Travelers may be at substantial risk for exposure to toxigenic strains of C. diphtheriae
, especially with prolonged travel, extensive contact with children, or exposure to poor hygiene.
This report describes a case of infection with toxigenic C. diphtheriae
in an American Indian woman and presents the results of enhanced surveillance for diphtheria in the surrounding community.
Nevertheless, emergence of nontoxigenic C. diphtheriae
infections has been reported in some of these countries.