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...

Trends in the evolution of antimicrobial resistance and mechanisms of resistance of Haemophilus influenzae to β-lactam antibiotics in France were assessed through a retrospective database review. The antimicrobial resistance of 2,206 H. influenzae strains from children aged ≤5 years was studied between 2001 and 2008. Strains were isolated from blood or cerebrospinal fluid (n = 170), bronchial secretions (n = 188), middle ear fluid, and nasopharynx or conjunctiva (n = 1,848). A proportion of 95.1 % (n = 2,097) were non-typeable H. influenzae (NTHi). β-lactamase production was identified in 27.5 % of NTHi isolates (all TEM-1), while β-lactamase-negative ampicillin resistance and β-lactamase-negative amoxicillin-clavulanate resistance among NTHi was 16.9 and 6.4 %, respectively. Over time, a statistically significant decrease in β-lactamase-producing strain prevalence (p < 0.0001) and a statistically significant increase in β-lactamase-negative ampicillin-resistant (BLNAR) strains (p < 0.0001) were observed in NTHi isolates from 2001 to 2008. The largest changes coincided with a campaign to reduce antibiotic use in France. An increasing diversity of amino acid substitution patterns was observed, with the emergence of group III/'III-like' patterns linked to high-level resistance. In France, amino acid substitution patterns are increasingly diverse, and strains with high-level antibiotic resistance are emerging. This study highlights the complexity of resistance dynamics within a given country. These results have implications on antibiotic guidelines and illustrate the importance of continued surveillance.

To diagnose invasive fungal infections, the detection of (1 → 3)-β-d-glucan in serum has shown variable specificity, depending on the targeted population. Several circumstances for false-positive results of beta-glucan tests have been identified, among which are severe bacterial infections. In this study, we measured (1 → 3)-β-d-glucan by the Fungitell test in the serum of 62 patients (one serum sample tested per patient) for whom invasive fungal infection was not suspected: 19 control subjects and 43 patients with bacteraemia. The test was interpretable for 58 sera: all 19 control subjects had negative beta-glucan test; among the 39 bacteraemic patients, we report 16 false-positive results. For the 22 patients undergoing bacteraemia due to Gram-negative bacilli, we observed 13 false-positive results (59%). Among the 17 patients with bloodstream infection involving Gram-positive cocci, three false-positive tests were recorded, but none in the eight cases of Streptococcus pneumoniae bacteraemia. Statistical analysis showed that beta-glucan levels were significantly higher in patients with Gram-negative bacilli bloodstream infection in comparison to those with bacteraemia due to Gram-positive cocci. These results were independent from other previously described causes for false-positive beta-glucan tests. These data might help physicians to interpret positive beta-glucan detection when an invasive fungal infection is suspected, especially for patients with bacterial infections.

The nasopharyngeal Haemophilus influenzae flora of healthy children under the age of 3 years attending day care centers in three distinct French geographic areas was analyzed by sampling during two periods, spring 1999 (May and June) and fall 1999 (November and December). The average carrier rate among 1,683 children was 40.9%. The prevalence of capsulated H. influenzae carriers was 0.4% for type f and 0.6% for type e. No type b strains were found among these children, of whom 98.5% had received one or more doses of anti-Haemophilus b vaccine. Among the strains, 44.5% were TEM-type beta-lactamase producers and nine (1.3%) were betalactamase-negative ampicillin-resistant strains. Pulsed-field gel electrophoresis restriction patterns showed a large diversity with 366 SmaI patterns from 663 strains. Among the strains isolated during a given period, 33% were isolated simultaneously in more than one area. In each area, depending on the sampling period, 68 to 72% of the strains had new pulsotypes and persistence of 28 to 32% of the strains was noted. For the 297 beta-lactamase-producing strains, 194 patterns were found. The genomic diversity of these strains was comparable to that of the whole set of strains and does not suggest a clonal diffusion. Among the beta-lactamaseproducing strains isolated in November and December, depending on the area, 66 to 73% had new pulsotypes with persistence of only 27 to 33% of the strains. In any given geographic area, colonization by H. influenzae appears to be a dynamic process involving a high degree of genomic heterogeneity among the noncapsulated colonizing strains.Haemophilus influenzae is one of the main bacterial species causing infection in children. Encapsulated strains are responsible for a variety of invasive diseases, the most frequent being meningitis, but epiglottitis, arthritis, pneumonia, and cellulitis also occur (36). These invasive diseases have decreased sharply since the generalization of anti-Haemophilus b (anti-Hib) vaccination (22, 37). Noncapsulated strains frequently cause acute otitis media in children (6,20,29,32). H. influenzae is often part of the nasopharynx flora and is frequently found in the upper respiratory tract of healthy children, with reported carriage rates of up to 60% (12,17,23,32).In the study of Faden et al. (9), 200 children were monitored from birth through to 2 years of age to determine the nasopharyngeal colonization pattern of nontypeable H. influenzae. Forty-four percent of the children were colonized on one or more occasions, and the acquisition rate was greatest in the first year. Colonization mainly involves a dominant strain which can be followed by a series of other strains (1,9,15,24). The level of carriage varies according to different factors, i.e., age, siblings, and living conditions. All of these factors can also have repercussions on the carriage of strains resistant to antibiotics or encapsulated type b strains. Anti-Hib vaccination has led to a sharp drop in the carriage of encapsulated type b strains (33).The turnove...

No abstract

The in-vitro activity of clarithromycin and its main metabolite 14-hydroxy clarithromycin against Haemophilus influenzae was evaluated by determining minimum inhibitory and minimum bactericidal concentrations. The 14-hydroxy metabolite was more active than the parent compound against H. influenzae. The activity of the parent compound/metabolite combination was evaluated against 20 strains of H. influenzae by the chequerboard technique. The combination was synergistic against seven isolates in terms of fractional bactericidal concentration index and against five isolates in terms of fractional inhibitory concentration index; the combination demonstrated additive activity against the remaining strains. Serum bactericidal activity against H. influenzae was measured in sera from six healthy volunteers who had received 250 mg clarithromycin by mouth. The area under the serum bactericidal activity curve correlated with the area under the curves for clarithromycin and 14-hydroxy clarithromycin, and with the in-vitro susceptibility of the strains tested. Serum bactericidal activity was detected at 30 min after dosing and lasted for 5-6 h.

No abstract

No abstract