DISTRIBUTION OF SEROTYPES AND BIOTYPES AND ANTIBIOTIC SUSCEPTIBILITY OF H. INFLUENZAE

Abstract

The distribution of serotypes and biotypes of 148 strains of H.Influenzae (H.i.) isolated from paediatric (103) and adult (45) patients was studied in order to confirm the association of non serotypable strains with disease and to investigate the correlation between some biochemical properties of the strains and certain illnesses. The susceptibility of the isolates to ampicillin (AM), chloramphenicol (CAF), cefuroxime (CXM), ceftizoxime (CZX), cefotaxime (CTX) and ceftazidime (CAZ) was also tested. Serotyping was performed by coagglutination and biotyping by the method of Kilian and by API 20 E. MICs were determined by the agar dilution technique. In 3 patients with invasive diseases (sepsis, menigitis) only capsulated type b H.i. were isolated, while in noninvasive acute (19 conjiunctivitis, 11 bronchopneumonia, 3 otitis media, 2 urethritis) and chronic (75 cystic fibrosis, 35 chronic bronchitis) diseases capsulated strains accounted for only 2/35 and 6/110 cases respectively. In patients with acute illnesses all the isolates belonged to biotypes I-II-III and did not produced lysine decarboxylase. In patients with chronic respiratory diseases 85/110 strains belonged to biotypes I-II-III while 25 were biotypes IV-V-VI; 43/110 produced lysine with decarboxylase. All AM resistant H.i. (3) were from patients with chronic respiratory illnesses No CAF resistant H.i. was isolated . CZX was more active of the cephalosporins tested followed by CTX,CAZ,CXM. These data confirm that also noncapsulated H.i. can be pathogenic; their virulence might be related to (and perhaps predictable by) biochemical typing.

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