Thirteen stool specimens obtained from eleven diarrheal patients who were hospitalized in neonatal unit were subjected to identify the causative agents of diarrhea and to provide an evidence of nosocomial infection by the method of molecular
epidemiology. Two kinds of nosocomial agents were confirmed. These were rotavirus and enteroaggregative E. coli(EAggEC). Eight stool specimens(61.5%) tested for human rotavirus were positive by Rotazyme test, whereas rotavirus specific
double-stranded
RNA by agarose gel electrophoresis analysis were detected in three stool specimens(23.1$%).
Any other pathogen than E. coli was not detected in bacterial culture. E. coli was isolated from all stool specimens and thirteen strains of E. coli were tested for the bacterial adherence to HeLa cells. Eight strains (61.5%) of E. coli which
showed an
aggregative adherence(AA) patterns were characterized by clumps of bacteria with "stacked-brick appearance". These strains attached to the surface of HeLa cells and to exposed bottom of the culture dish between HeLa cells. When these strains were
tested
to identify EAggEC, none was hybridized with 700 basepairs of Pcvd432 probe.
Except one of the total 13 diarrheal specimens showed either one or both of EAggEC and rotavirus. Each eight specimens were positive EAggEC and rotavirus, Among them, 4 patients were concomitantly infected by EAggEC and rotavirus.
E. coli strains confirmed to be EAggEC were further tested for the in detailed study. All of 8 strains appeared to be multiple resistant to more than 4 drugs among 8 drugs tested. Two strains were multiple resistant to 5 or 6 drugs,
streptomycin(Sm),
sulfamethoxazole(Su), ampicillin(Ap), kanamycin(Km), tetracycline and/or chloramphenicol.
The rest 6 strains showed strikingly same antibiogram of SmSuApKm. Moreover, these strains showed an exactly identical plasmid fingerprinting which consisted of five different molecular sizes(61.8, 4.3, 3.5, 2.7, and 2.4 megadalton).
Integrated data demonstrated a critical evidence of nosocomial outbreaks of EAggEC infection and rotavirus that originated from common source in a neonatal unit of hospital.
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