National collaborative study of the prevalence of antimicrobial resistance among clinical isolates of Haemophilus influenzae

Abstract

A total of 2,811 clinical isolates of Haemopbilus influenzae were obtained during 1986 from 30 medical centers and one nationwide private independent laboratory in the United States. Among these, 757 (26.9%) were type b strains. The overall rate of 3-lactamase-mediated ampicillin resistance was 20.0%. Type b strains were approximately twice as likely as non-type b strains to produce (-lactamase Antimicrobial resistance among clinical isolates of Haemophilus influenzae has become an increasingly prevalent problem (G. V. Doern, Antimicrob. Newsl. 5: [28][29][30][31][32][33][34] 1986). In a national collaborative study conducted in 1984, 15.2% of a large number of strains of H. influenzae produced Ilactamase (6). The problem of ampicillin resistance is complicated by recent descriptions of clinical isolates of H. influenzae that are resistant to ampicillin by mechanisms other than the production of a TEM-type P-lactamase (10,11,14). In addition, chloramphenicol resistance has now been reported (2,15), as has resistance to a variety of alternative agents commonly used to treat Haemophilus infections (Doern, Antimicrob. Newsl. 5:28-34). The intent of this investigation was to define systematically the prevalence of antimicrobial resistance among clinical isolates of H. influenzae in the United States. Rates of P-lactamase production and the activities of 12 antimicrobial agents were assessed. These agents included ampicillin, chloramphenicol, cefamandole, cefaclor, cephalothin, cephalexin, tetracycline, rifampin, erythromycin, sulfisoxazole, and the combinations erythromycin-sulfisoxazole and trimethoprim-sulfamethoxazole (TMP-SMX). MATERIALS AND METHODSStudy centers. A total of 30 hospital-based microbiology laboratories and 1 national, private, independent laboratory participated in the study (Table 1) by the laboratories listed in Table 1. All isolates were recovered from different patients and were randomly selected for inclusion in the study. After being characterized in study center laboratories, isolates were subcultured to chocolate agar slants (GIBCO Diagnostics, Madison, Wis.), which were incubated overnight in a CO2 atmosphere and then mailed, with selected patient demographic information, to one of two coordinating study centers for further characterization. The coordinating study centers were the Department of Clinical Microbiology, University of Massachusetts Medical Center, Worcester, and the Department of Pathology, University of Texas Health Science Center, San Antonio. Upon receipt in the coordinating study centers, growth from slants was transferred into 10% sterile skim milk and frozen at -70°C in 1-dram (ca. 3.7-ml) plastic freezer vials.Isolate characterization. Frozen stock suspensions were thawed, and aliquots were subcultured to chocolate agar plates (GIBCO) which were incubated overnight at 35°C in 5 to 7% CO2. Individual isolated colonies were then subcultured to a second chocolate agar plate which was incubated under identical conditions. Growth from the second plate was used for the fol...

Antimicrobial susceptibility of Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae isolates causing meningitis in The Netherlands, 1993-1994

“…A significantly higher prevalence of ampicillin resistance was found among our type b as compared with non-type b strains. This was also seen in the USA, but not in previous studies from Europe and South Africa (Doern et al, 1988;Kayser et al, 1990;Hussey et al, 1994). One study mentioned highest rates of ampicillin resistance among children aged less than 5 years, comparable to our findings (Doern et al, 1988).…”

“…These findings are similar to prevalences among isolates from different types of specimen in nine European countries and South Africa (1991-92) (Kayser, Morenzoni & Santanam, 1990;Hussey et al, 1994). In the USA ampicillin resistance in H. influenzae occurred twice as often, yet chloramphenicol resistance was rare (Doern et al, 1988). A significantly higher prevalence of ampicillin resistance was found among our type b as compared with non-type b strains.…”

“…This was also seen in the USA, but not in previous studies from Europe and South Africa (Doern et al, 1988;Kayser et al, 1990;Hussey et al, 1994). One study mentioned highest rates of ampicillin resistance among children aged less than 5 years, comparable to our findings (Doern et al, 1988). As the outcome of patients with H. influenzae meningitis caused by strains which were resistant to initial therapy consisting of ampicillin and chloramphenicol appeared to be worse in one study, this regimen cannot be recommended now for H. influenzae meningitis in The Netherlands (Campos et al, 1986).…”

Antimicrobial resistance patterns of Haemophilus influenzae isolated from patients with meningitis in São Paulo, Brazil

“…The present study shows that the overall rate of ß-lactamase producers in H. influenzae was 13.8%. Similar results have also been obtained in a collaborative study conducted in the US during the 80s and in São Paulo during the 90s (20,21). In Finland and in South Africa the overall rate of ß-lactamasemediated ampicillin resistance in H. influenzae was 10% (11,22,23).…”

Antibiotic Susceptibility of the Sputum Pathogens and Throat Swab Pathogens Isolated from the Patients Undergoing Treatment in Twenty-one Private Clinics in Japan.

“…The incidence of isolation of ampicillin-resistant strains of H. influenzae and S. pneumoniae in the present study was as high as that in intensivemedication-oriented clinics in Japan (Nishioka et al 1991;Tanabe et al 1993), and in Europe and USA (Jacobes et al 1978;Ward 1981;Appelbaum 1987Appelbaum ,1992; Doern et al 1988;Righter and Luchsinger 1988). On the other hand, a significant difference was found in the incidence of MRSA between the primary care clinics and the intensive-medication-oriented clinics.…”