HAEMOPHILUS-INFLUENZAE BETA-LACTAMASE-PRO DUCING STRAINS ISOLATED IN PORTUGAL BETWEEN 1989-1992

Within the framework of a national multicentric study between 1989 and 1992, 118 strains of betalactamase producing Haemophilus influenzae w ere isolated. Biotyping demonstrated the predominance of biotypes I, I I and III, with 22, 36 and 24 % of the strains, respectively. Encapsul ated strains accounted for 13 % of the total; all, but one, were serot ype b. The antimicrobial susceptibility test (dilution method) of the 118 ampicillin - resistant strains showed : 33.9 % resistance to tetra cycline, 29.7 % to chloramphenicol, 10.2 % to erythromycin, 9.3 % to t rimethoprim, 0.8 % to rifampicin, and 29.7 % of multiresistance. All s trains were susceptible to augmentin, cefotaxime, ceftriaxone and cepr ofloxacin. Ninety strains were screened for resistant plasmids. A larg e plasmid (30-50 Mdal) was isolated in 38,9 % of the strains and a sma ll plasmid (3-4,4 Mdal) in 10 %. No plasmid was found in 51 % of the s trains. Isoelectric focusing of 54 beta-lactamases showed that all wer e type TEM-1 (pI =5,4), with the exception of one, wich was type TEM-2 (pI =5,6).