Microbiological and molecular epidemiological studies were conducted on 36 multi-resistant Haemophilus influenzae strains, isolated from paediatric patients, over a 26 month period (April 1986 to May 1988). The majority of strains (80,5%) had been isolated from blood and cerebrospinal fluid. More than 80% of isolates tested belonged to biotype II and 90% were of serotype B. Minimal inhibitory concentrations against 6 antibiotics (ampicillin, chloramphenicol, tetracycline, rifampicin, streptomycin and cefotaxime) confirmed the presence of multi-resistant strains. Resistance to rifampicin was confirmed in 6 (16,7%) strains. All strains were susceptible to cefotaxime. Ten transconjugants analysed with respect to their plasmid content were shown to harbour an identical 41 MDa plasmid. Restriction endonuclease digests of these plasmids with Eco R1 and Sst1 revealed almost identical restriction patterns. Outer membrane protein profiles of 19 strains revealed the predominance of one particular subtype. By combining the microbiological and molecular epidemiological findings, it is concluded that one strain of H. influenzae type b is responsible for the nosocomial acquisition of infections amongst paediatric patients. The implifications of these findings are discussed.

Thesis (M.Med.)-University of Natal, Durban, 1988.