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Campylobacter species are increasingly being recognized as agents of gastroenteritis worldwide. However, data on the pathogenic characteristics of the organism isolated in rural communities in South Africa are lacking. In this study, the prevalence of Campylobacter spp. from diarrhoeal stools, haemolytic and haemagglutinating activities of the isolates, and antibiotic susceptibility profiles, including minimum inhibitory concentration (MIC) patterns to different antibiotics, were determined using the standard microbiological techniques. Campylobacter spp. were isolated from individuals of all age-groups; however, the infection rate was higher among individuals aged less than two years (30.4%). Of 115 Campylobacter strains isolated, polymerase chain reaction (PCR) analysis indicated that 98 (85%) were C. jejuni, while 17 (15%) were C. coli. Seventy-one (62%) of the strains showed haemolysis on human blood, and 80% agglutinated human blood, whereas 22.6% were beta-lactamase-positive. Resistance to antimicrobials, such as erythromycin, ciprofloxacin, vancomycin, and fusidic acid, was high. Increased resistance to macrolide and quinolone antibiotics poses major risks for treatment failure. Haemolytic and haemagglutinating activities may be useful in preliminary characterization of pathogenic strains in settings where Campylobacter-associated infections are common.

Campylobacteriosis is a collective description for infectious diseases caused by members of the bacterial genus Campylobacter. The only form of campylobacteriosis of major public health importance is Campylobacter enteritis due to C. jejuni and C. coli. Research and control efforts on the disease have been conducted more often in developed countries than developing countries. However, because of the increasing incidence, expanding spectrum of infections, potential of HIV-related deaths due to Campylobacter, and the availability of the complete genome sequence of C. jejuni NCTC 11168, interest in campylobacteriosis research and control in developing countries is growing. We present the distinguishing epidemiologic and clinical features of Campylobacter enteritis in developing countries relative to developed countries. National surveillance programs and international collaborations are needed to address the substantial gaps in the knowledge about the epidemiology of campylobacteriosis in developing countries.

Campylobacter jejuni (10(8) C.F.U) fed intragastrically unto 18 laboratory rats (white whiskers) resulted in colonization of the 18 rats intestines and their eventual excretion of the organism for four months post infection. When 10(8) CFU of C. jejuni was mixed with 10 mu/ml of cadmium chloride (CdCl2) and fed immediately to another set of 18 rats, colonization of rats intestines was greatly reduced and C. jejuni was recovered from two (11%) out of 18 rats and the faeces were positive for C. jejuni for a maximum of 29 days. Six control rats given 1 ml of phosphate buffered saline (PBS) and a second set of another six control animals given 1 ml of PBS containing 10 micrograms/ml of CdCl2 gave negative result for C. jejuni throughout the experiment. This work depicts an in vivo effect of CdCl2 on C. jejuni and may be of importance in the control of C. jejuni colonization in experimental animals.

Seventy patients with acute diarrhoea and sixty asymptomatic children in Lagos, Nigeria were screened for complement fixing and agglutinating antibodies to Campylobacter jejuni in wells of microtitre plates using automatic microtitre pipettes. Out of the seventy patients with acute diarrhoea, 55 (78.6%) had complement fixing antibody, while 48 (68.5%) had agglutinating antibody in their sera. Twenty-nine (48.3%) and 21 (35%) out of the sixty asymptomatic children screened had complement fixing and agglutinating antibody respectively. Generally 84 (64.6%) of 130 children (both symptomatic and asymptomatic) had antibody to C. jejuni in their sera. The difference in the incidence rate between the symptomatics and asymptomatic is not statistically significant. The result suggest an antibody response to C. jejuni among children with diarrhoea, indicating that most of the diarrhoea cases in our environment may be due to Campylobacter but the successful demonstration of antibody response to C. jejuni among asymptomatic individuals may also suggest that even "normal" individuals have in their sera, antibody that can agglutinate C. jejuni in Nigeria. Use of antibody responses alone to C. jejuni in the diagnosis of C. jejuni infections in Nigeria should therefore be interpreted with caution.

Limulus gelation assay and dermal Schwartzman reaction provided a sensitive and reproducible means of testing the endotoxic activity of hospital strains of Campylobacter jejuni in Lagos, Nigeria. All the 22 isolates of Campylobacter jejuni tested for the limulus gelation assay were positive for the production of endotoxin. Furthermore, the Campylobacter suspensions caused a positive dermal Schwartzman reaction in rabbits. The area of skin reaction was less extensive than that produced by Escherichia coli 01114B and E7539/77 which served as positive controls. Five local strains of Campylobacter jejuni tested for enterotoxin production showed negative reaction in the infant mouse test whereas enterotoxin production was observed in Campylobacter jejuni strain 11168 and Escherichia coli E7539/77. Consequently, the infant mouse test may not be suitable for enterogenicity testing of our local isolates of Campylobacter jejuni.

The role of macrophages in experimental campylobacteriosis was studied in mice whose macrophages had been blocked using colloidal carbon particles as the blockading agent. Two sets of mice received 0.4 ml intraperitoneally and 0.4 ml intravenously of colloidal carbon, respectively, and each set was then inoculated with a clinical isolate of Campylobacter jejuni intraperitoneally. The treatment resulted in a lethality of 66.6% in mice given colloidal carbon intraperitoneally and 58.0% in mice given colloidal carbon intravenously within the first three days post infection. The control groups (mice injected only with C. jejuni) had a lethality of 16.6% (p less than 0.05). Mice receiving only colloidal carbon showed no lethality. These results suggest that the activities of macrophages as scavenger cells are important factors in the defence mechanism of mice against experimental campylobacteriosis.