Quantitative measurements of Hemophilus influenzae type b capsular polysaccharide antibodies in Japanese children.

BACKGROUND: Hemophilus influenzae type b (Hib) infection has a high morbidity and mortality rate in children. The frequency of natural immunity against Hib in Japanese children is not known, and Hib vaccine has not yet been introduced in Japan. METHODS: Anti-capsular polysaccharide-specific IgG (anti-CP) antibody titers were examined in serum samples from 100 children and 107 young adults who were not vaccinated against Hib, in serum samples from eight patients with Hib systemic infection and in 10 commercially available human immune globulin preparations on enzyme-linked immunosorbent assay. RESULTS: A total of 44% (44/100) of Japanese children and all patients with Hib systemic infection in the acute phase did not have the minimum protective level of anti-CP antibodies (>0.15 microg/mL). The rate of natural Hib immunity was lowest in children under 1 year of age and gradually increased with age. Only 3.74% (4/107) of Japanese young adults did not have the minimum protective level of anti-CP antibodies. Analysis of 10 commercially available human immune globulin preparations indicated an average level of 28.25 microg anti-CP antibody/mL immune globulin (range 14.96-44.17 microg/mL). CONCLUSIONS: Approximately half of Japanese children are not protected against Hib infection. Therefore, Hib vaccine should immediately be included as part of the routine immunization program in Japan. It was also found that all tested commercially available immune globulin preparations had high anti-CP titers. Well-controlled clinical trials of i.v. immune globulin administration for prevention and treatment of Hib systemic infection are needed in Japan.

[Studies of treatment for Haemophilus influenzae type b meningitis in children].

We summarize 41 cases of bacterial meningitis in the last 11 years caused by Haemophilus influenzae. All isolates were serotype b strain (Hib). Initial chemotherapy was started with ceftriaxone (CTRX) in 22 cases, ampicillin plus cefotaxime (CTX) in 9, CTRX plus panipenem/betamipron in 5, and CTX in 2. Some 31 cases were treated mainly with CTRX. Although therapeutic antibiotics showed good susceptibility for isolates, 8 complicated cases (19.5%) occurred. Sequalae were observed in 7 (17.1%) but none were fatal. Five strains with elevated MIC of CTX (0.12 to 1 microg/mL) recovered after 2001, and 3 of 5 strains also showed elevated MIC of CTRX (0.12 to 0.5 microg/mL), but all were cured completely with CTRX. At present, no treatment failures due to antibiotic resistance have been observed, and CTRX remains suitable as initial therapy for Hib meningitis. A decline in susceptibility for third-generation cephalosporin against beta-lactamase-nonproducing ampicillin-resistant H. influenzae is emerging, however, so it will be necessary to consider combination therapy with CTRX given the foreseeable trend in MICs.

[Clinical effects of piperacillin and tazobactam/piperacillin on Haemophilus influenzae lower respiratory tract infection in pediatric patients].

OBJECTIVE: The prevalence of beta-lactamase-nonproducing ampicillin-resistant (BLNAR) Haemophilus influenzae (H. influenzae) has been increasing in recent years. Piperacillin (PIPC) is one of a few beta-lactams possessing good activity against BLNAR H. influenzae. We studied clinical efficacy of piperacillin and its beta-lactamase inhibitor, tazobactam/piperacillin (TAZ/PIPC) in children with lower respiratory tract infection caused by H. influenzae including resistance strains. METHODS: Subjects were 20 children with lower respiratory tract infection caused by H. influenzae treated with PIPC 100mg/kg/day (7 cases) or TAZ/PIPC 125mg/kg/day (13 cases). We selected cases from which resistant H. influenzae strains might be detected. Patients received prior antimicrobial therapy within two weeks before admission, or with underlying diseases. We examined patient profiles, clinical efficacy, susceptibilities for 6 beta-lactam antibiotics [PIPC, TAZ/PIPC, ampicillin (ABPC), cefotaxime (CTX), ceftriaxone (CTRX), and meropenem (MEPM)] and analyzed 6 genotype patterns of beta-lactam resistant genes by PCR. RESULTS: Efficacy was 7/7 in patients in PIPC group and 12/13 in patients in TAZ/PIPC group. Diminished efficacy was seen in only one case complicated with severe RSV infection. The susceptibility of all strains but one beta-lactamase producing, ABPC resistant (BLP) strain to PIPC and of all to TAZ/ PIPC was below 0.25 microg/mL. The genotype of the 15 strains isolated from the sputum on administration was as follows; beta-lactamase nonproducing, ABPC-susceptible (gBLNAS) strains were 4, gBLP strain was 1, beta-lactamase nonproducing, and ABPC-resistant (gLow-BLNAR) strains were 2, beta-lactamase nonproducing, ABPC resistant (gBLNAR) strains were 8. CONCLUSION: PIPC and TAZ/PIPC were useful against lower respiratory tract infection caused by H. influenzae including BLNAR in children.