Resistance of clinical isolates of Haemophilus influenzae in United Kingdom 1986.

Abstract

ampicillin 7-8% (6-2% P-lactamase producers and 1-6% nonproducers), tetracycline 2 , chloramphenicol 1.7%, trimethoprim 4.2%, and sulphamethoxazole 3-5%. Of the 87 capsulated strains, 15 produced P-lactamase, nine were resistantto ampicillin but did not produce P3-lactamase, and two strains, one of which produced P-lactamase, were resistant to chloramphenicol and tetracycline.Since 1977 the prevalence ofresistance to ampiciflin, chloramphenicol, and trimethoprim has increased significantly. During

Antimicrobial resistance in Haemophilus influenzae

“…influenzae type-b infections which failed to respond to ampicillin therapy prompted some of the earliest reports of resistance to antimicrobial agents in use against this species (Gunn et al, 1974). The prevalence of P-lactamase-producing H. influenzae identified from United Kingdom surveys rose from 1 -6% in 1977 (Howard et al, 1978) to 18% amongst type-b isolates and 6.2% overall in 1986 (Powell et al, 1987). In Europe, p-lactamase production is most common among type-b (64%) and non-capsulate (26%) Spanish isolates (Machka et al, 1988).…”

“…The prevalence of resistance to trimethoprim in the UK reached 4.2% in 1986 (Powell et al, 1987). Few international studies have reported on resistance to trimethoprim not tested in combination with sulphamethoxazole.…”

“…Tetracycline resistance remains at <3% in the UK (Powell et al, 1987). Although resistance to tetracycline may occur without resistance to chloramphenicol, a high prevalence is generally seen only in those areas where the latter is high.…”

“…In a survey in the UK in 1986 (Powell et al, 1987) 100 isolates (4.1%) were identified that showed reduced zone diameters ( c 20 mm) to 2-pg ampicillin disks and required ampicillin concentrations between 1 and 64 mg/L for inhibition. These isolates appear to be generally uncommon in Europe (Machka et al, 1988) and the USA (Doern et al, 1988), but it is not possible to gauge accurately the worldwide prevalence of this non-lactamase-mediated ("intrinsic") resistance because of the problems which have become apparent in its detection.…”

“…influenzae of Pittman (capsule) type b merit separate consideration because of their propensity to cause invasive infections. Several national studies have reported a consistently higher prevalence of P-lactamase production among isolates of type b when compared with non-capsulate H. inJIuenzae (Doern et al, 1986;Powell et al, 1987;Machka et al, 1988) and some have found that type-b isolates are more likely to be resistant to other antimicrobial agents (Dabernat et al, 1986). Although they are responsible for most cases of invasive disease, this difference is also seen between type-b isolates producing non-invasive disease and the non-capsulate organisms more commonly responsible for less serious infections.…”