The sequences of the ftsI gene, encoding the transpeptidase domain of penicillin binding protein (PBP) 3A and/or PBP 3B, which are involved in septal peptidoglycan synthesis, were determined for 108 clinical strains of Haemophilus influenzae with reduced susceptibility to ␤-lactam antibiotics with or without ␤-lactamase production and were compared to those of the ampicillin-susceptible Rd strain and ampicillin-susceptible clinical isolates. The sequences have 18 different mutation patterns and were classified into two groups on the basis of amino acid substitutions deduced from the nucleotide sequences located between bp 960 and 1618 of the ftsI gene. In group I strains (n ‫؍‬ 7), His-517 was substituted for Arg-517. In group II strains (n ‫؍‬ 101), Lys-526 was substituted for Asn-526. In subgroup IIa (n ‫؍‬ 5; H. influenzae ATCC 49247), the only observed substitution was Lys-526 for Asn-526; in subgroup IIb (n ‫؍‬ 56), Val-502 was substituted for Ala-502 (n ‫؍‬ In spite of the widespread use of the anti-Haemophilus b vaccine in the industrialized countries and the decreased incidence of invasive diseases (18), Haemophilus influenzae remains a key species in bronchopulmonary and ear, nose, and throat (ENT) infections in both adults and children. These diseases are most often caused by noncapsulated strains (10,14). Treatment of such infections can be severely affected by antibiotic resistance. In H. influenzae resistance to antibiotics, especially to ␤-lactams, has, for a number of years, become a serious problem (6,15,30).Two main mechanisms are at the origin of resistance to aminopenicillins: enzymatic hydrolysis of the antibiotic and a change in penicillin-binding proteins (PBPs). By far the more frequent is the production of ␤-lactamase, usually of the TEM-1 type but sometimes of the ROB-1 type (15,32). In certain countries, the incidence of strains producing ␤-lactamase is particularly high, reaching 50% in type b strains, which are responsible for invasive manifestations (before anti-Haemophilus b vaccination), and 20 to 30% in noncapsulated strains that lead to bronchopulmonary and ENT infections (5, 12, 32).Resistance by mechanisms other than ␤-lactamase production is based on decreased affinity of the PBPs involved in septal peptidoglycan synthesis (4). The first observations of ampicillin-resistant non-␤-lactamase producing (BLNAR) strains were reported in the early 1980s and concerned type b capsulated (20, 27) and noncapsulated strains (2, 25). In contrast to the incidence of ␤-lactamase-producing strains, the incidence of BLNAR strains remains low in various countries (4,5,8,32), but in Japan the proportion of BLNAR clinical isolates is more than 25% and seems to be increasing (33,36).In H. influenzae, ampicillin resistance unrelated to ␤-lactamase production was shown to be chromosomally mediated and was correlated with alterations in PBPs 3A and 3B (4,22,29,34). Recently, Ubukata et al. (36) demonstrated that mutations in the ftsI gene, which is involved in septal peptidoglycan synthesis, are th...

A collection of 2,209 isolates of six polysaccharide capsule types of Haemophi/us influenzoe, including 1,975 serotype b isolates recovered in 30 countries was characterized for electrophoretically demonstrable allele profiles at 17 metabolic enzyme loci. Two hundred eighty distinct multilocus genotypes were distinguished, and cluster analysis revealed two primary phylogenetic divisions. The population structure of encapsulated H. influenzae is clonal. Currently, most of the invasive disease worldwide is caused by serotype b strains of nine clones, Strains producing serotype c, e, and f capsules belong to single divisions and have no close genetic relationships to strains of other serotypes, Serotype a and b strains occur in both primary phylogenetic divisions, probably as a result of transfer and recombination of serotype-specific sequences of the cap region between clonal lineages. A close genetic relatedness between serotype d isolates and some strains of serotypes a and b was identified, There are strong patterns of geographic variation, on an intercontinental scale, in both the extent of genetic diversity and the clonal composition of populations of encapsulated strains, The analysis suggests that the present distribution of clones is, in part, related to patterns of racial or ethnic differentiation and historical demographic movements of the human host populations.

The first European survey of the prevalence of antibiotic resistance in Haemophilus influenzae was conducted between February and October 1986. Eighty laboratories in nine countries participated (Austria, Belgium, France, FRG, The Netherlands, Spain, Sweden, Switzerland and the UK). A total of 1,961 clinical isolates was examined for type b encapsulation, beta-lactamase production and susceptibility to ampicillin, chloramphenicol, cefaclor, erythromycin and tetracycline, using a unique microdilution method. The proportion of isolates resistant to these antibiotics varied considerably between individual countries. The highest prevalence of ampicillin resistance was found in Spain (30.6%), and the lowest in the FRG (1.6%), with a mean value of 10% for all countries. Chloramphenicol resistance was highest in Spain (24.9%) and Belgium (10.9%) and lowest in The Netherlands (0.6%) and Austria (0.5%), with a mean value of 4.7%. Resistance to erythromycin ranged from 27% of the isolates in The Netherlands to 1.1% in Austria. For tetracycline, values ranged from 1.5% in the UK to 17.8% in Belgium and 25.4% in Spain. The lowest mean prevalence of resistance was observed for cefaclor (breakpoint 8 mg/l): 5% or less in all countries. These inter-country differences could only partially be explained by variations in the proportion of type b strains, the source of the isolates and the mode of collection.

A multicentre, open-label, randomized study was performed in 501 out-patients with acute otitis media, aged 6-36 months, to study the impact of treatment with either cefixime suspension 8 mg/kg/day bd or co-amoxiclav suspension 80 mg/kg/day tds for 10 days on nasopharyngeal carriage of Streptococcus pneumoniae and Haemophilus influenzae. Of 426 patients with nasopharyngeal cultures at entry to the trial, end of treatment and at follow-up visit (35 days after inclusion), significant changes in carriage of S. pneumoniae were observed. The proportion of penicillin-resistant S. pneumoniae was higher in the samples taken at the end of treatment and follow-up than in those taken at inclusion, while the total number of children with this microorganism was lower. The difference at the end of treatment was greater with co-amoxiclav than with cefixime. For H. influenzae the resistance rate remained steady while the number of children with this microorganism decreased. At follow-up there was no significant difference between the two groups in terms of nasopharyngeal positive culture for S. pneumoniae or H. influenzae. Despite these differences, successful clinical responses were similar at the end of treatment and at follow-up.