Search

From patients in Nigeria with acute gastroenteritis, strains of Yersinia were isolated from 14 (1.3%) of 1082 specimens of faeces examined specifically for yersiniae by direct plating and after cold enrichment. Clinical significance was ascribed to six isolates of Y. enterocolitica (serotypes 03, 05,27 and 09) but not to seven isolates of Y. intermedia or one isolate of Y. frederikseni.

Solutions of potassium hydroxide and sodium hydroxide with concentrations between 0.5% and 4% were found to produce mucoid and sticky suspensions when added in drops, using a bacteriological loop, to smears of 609 strains of gram-negative bacteria on glass slides. A total of 461 strains of gram-positive bacteria and yeasts did not produce any mucoid or "string" formation when treated with the same solutions. It was concluded that this modified test could aid in differentiating gram-positive from gram-negative organisms.

Although Yersinia enterocolitica has been isolated in a few cases in some tropical countries, it is more prevalent in cold European countries. Recently, several reports have incriminated pig and pork as the chief reservoirs of Y. enterocolitica. To determine the presence of this organism in Dacca, we attempted to isolate it from 212 stool samples from patients with a clinical picture resembling yersiniosis, 113 other stool samples from patients with diarrhoea, 30 appendices from appendectomized patients and 190 stool samples from animals with diarrhoea. No Y. enterocolitica was detected. This may be due to Dacca's warm climate: the 18-year average temperature for January (coldest month) is 18.5 degrees C. The effect of environmental temperature on Y. enterocolitica needs further investigation. An alternative explanation may be the prohibition on eating pork and the virtual absence of pig rearing in Bangladesh, a Muslim country. In fact, to date only one case of yersiniosis has been reported from a Muslim country (Iran).

Fourteen strains of Yersinia species isolated from apparently healthy pigs and cattle in Nigeria were screened for four virulence markers using six test systems. These were two in vitro assays, namely, calcium dependency and autoagglutination, both at 37 degrees C, the Serény test in guinea-pigs and the detection of heat-stable enterotoxin (ST) by the rabbit ileal loop test, the ligated intestine test in pigs and the infant mouse system. Seven of the 14 strains of Yersinia were positive for one or more of these tests. Six of nine strains of Y. enterocolitica and one of four Y. intermedia were positive in one or more tests. The only strain of Y. frederiksenii isolated was negative in all six test systems. All three strains of Y. enterocolitica, serotype 0:8 and the only serotype 0:3 isolated were positive in one or more tests. However, only two of five strains of Y. enterocolitica serotype 0:12, 26, the most frequently encountered, were positive. A good correlation was observed between test results of calcium dependency, autoagglutination and Serény assays. The results indicate that cattle and pigs have the potential to transmit virulent strains of Y. enterocolitica to human beings in Nigeria.

Enteropathogenic, enterotoxigenic and enteroinvasive Escherichia coli were isolated from 52 (4.8%) of 1,082 patients with acute gastroenteritis reporting at the Lagos University Teaching Hospital, Lagos, Nigeria between October 1979 and March, 1981. Of the 52 strains of E. coli isolated, 35 (67.3%) were enteropathogenic, 12 (23.1%) were enterotoxigenic and five (9.6%) were enteroinvasive. E. coli 0111 (25.7%) was the most predominant among the serotypes of the "classical" enteropathogenic strains found in this study. Diarrhoea associated with enteropathogenic E. coli occurred only in children aged less than five years, whereas enterotoxigenic and enteroinvasive E. coli were found primarily in adults. The study has highlighted for the first time the important role that enterotoxigenic and enteroinvasive E. coli strains could play in acute diarrhoeal diseases in Lagos, Nigeria.

Water samples obtained from 250 wells, 118 ponds and 34 streams around Zaria, Nigeria were cultured for Yersinia enterocolitica. All samples tested were negative for the microorganism. Water samples from the three sources experimentally inoculated with three strains of Yersinia enterocolitica allowed an initial multiplication followed by a progressive decline in population with increase in population paralleling increase in ambient temperature. Well water was most supportive of the organism but strain variability in survival was observed in water from the three sources. Stream, pond and well water may not be important in the epidemiology of Y. enterocolitica infections in animals and human beings in Northern Nigeria.