Molecular Epidemiology of Ampicillin-Resistant Non-β-Lactamase-Producing Haemophilus influenzae

Abstract

Resistance to ampicillin without β-lactamase production is not a frequent occurrence among Haemophilus influenzaestrains. This kind of resistance is encountered in unencapsulated strains isolated from bronchial secretions and ear, nose, and throat specimens and is exceptional in H. influenzae type b. We studied 29 of these strains from various areas in France and 2 reference strains. Strains were compared by using ribotyping, arbitarily primed PCR with two primers, and pulsed-field gel electrophoresis. Each technique enabled the identification of 20 to 23 different patterns among the 31 strains. The combination of the different patterns for the strains obtained by the different techniques provided 27 distinct profiles. According to these results, it seems that the clonal propagation of these resistant strains does not occur.

Antibiotic susceptibility and genotypic characterization of Haemophilus influenzae strains isolated from nasopharyngeal specimens from children in day-care centers in eastern France

“…The frequency of ampicillin resistance among H. influenzae isolates not producing β‐lactamase was 2.27%, consistent with reported rates [13,30]. This resistance in isolation affected principally the activity of cefaclor, with lesser effects on the activity of cefuroxime–axetil, ceftriaxone and cefpodoxime [34–37], but strains with this type of resistance did not seem to have major clinical consequences [38]. For our isolates, the MIC of erythromycin in the erythromycin–sulfisoxazole combination was lower than that of erythromycin alone, but higher than the plateau level of about 1.1 mg/L obtained for samples of middle ear effusion [39].…”

Resistance patterns of selected respiratory tract pathogens in Poland

“…PFGE analysis revealed that the population of isolates with altered PBPs in Poland is diverse, as has been described previously for non‐typeable BLNAR isolates [29–31]. However, the identification of isolates with the same or very similar PFGE patterns, not only from patients attending the same hospital, but also from different parts of the country, suggests possible clonal spread of isolates with altered PBPs, as has been observed previously [32].…”

Subtyping of Haemophilus influenzae Strains by Pulsed-Field Gel Electrophoresis

“…They also studied the strains using other molecular biology tools, ribotyping and arbitrarily primed PCR with two primers, and each technique gave nearly the same number of different patterns as PFGE. However, ribotyping is more fastidious and time-consuming than arbitrarily primed PCR and PFGE (6).…”