No abstract

The largest diphtheria outbreak in the developed world since the 1960s began in the Russian federation in 1990. One hundred fifty-six Corynebacterium diphtheriae strains from throughout Russia, selected for temporal and geographic diversity, were assayed by ribotyping and multilocus enzyme electrophoresis (MEE). These tests showed significant genetic diversity within the C. diphtheriae species, and ribotyping and MEE data generally correlated well with epidemiologic data. A distinct clonal group of C. diphtheriae isolates (ET 8 complex) emerged in Russia in 1990 as the current outbreak began, and as the outbreak has progressed, these organisms have made up increasingly larger proportions of the strains that are isolated. Furthermore, the main characteristic of the epidemic strains is a specific combination of ET 8 and ribotypes G1 and G4. This study confirms the epidemiologic utility of the molecular subtyping methods that detected the epidemic clone and addresses the clone's origin and relation to C. diphtheriae from throughout Russia.

Epidemiologic investigation of group B streptococcal (GBS) infections has been limited by the lack of a discriminatory typing system. Therefore, the use of restriction endonuclease analysis of chromosomal DNA (REAC) and DNA restriction fragment length polymorphisms of rRNA genes (ribotyping) to subtype molecularly GBS isolates associated with human invasive disease was investigated. Chromosomal DNA of selected GBS isolates was initially digested with 24 different restriction enzymes. HhaI gave the best discrimination of hybridization banding patterns (ribotypes) and was used with all study isolates. Ribotyping and REAC differentiated among isolates of the same and different serotypes. Nine ribotype patterns were noted among the 76 isolates studied, including 4 among serotype Ia/c and 4 additional ribotypes among serotype III isolates. Epidemiologically related isolates (e.g., mother-infant or twin-twin pairs) had identical REAC and ribotype patterns. Epidemiologically unrelated isolates with the same ribotype usually had different REAC patterns, suggesting that REAC may be a more sensitive technique for strain differentiation. REAC and ribotyping were reproducible and proved to be successful molecular epidemiologic methods for subtyping GBS.

Between December, 1974, and August 1975, intestinal illness occurred in 55 of 205 infants admitted to the special-care nurseries of a large children's hospital. Escherichia coli serotype 078:K80:H12, which produced a heat-stable enterotoxin, was isolated from 18 of 25 symptomatic infants as compared with 14 of 55 asymptomatic infants (P less than 0.001). Colistin administered prophylactically to 24 culture-negative asymptomatic infants did not prevent colonization in 10, whereas colonization did occur in 22 of 56 not receiving colistin (P = 1.0). This outbreak provides laboratory and epidemiologic evidence that heat-stable enterotoxigenic Esch. coli is pathogenic in human beings and produces infantile diarrhea.