Antimicrobial susceptibility of respiratory Haemophilus influenzae strains isolated from pediatric respiratory tract infections

BACKGROUND: Haemophilus influenzae (H. influenzae) is the most frequent bacterial pathogen of respiratory tract infections in children. Detection of antimicrobial susceptibility of H. influenzae is necessary for institution of appropriate antibiotic treatments. METHODS: A total of 281 strains of H. influenzae isolated from sputum samples of 281 pediatric patients with respiratory tract infections were recruited for study. Antibiotic susceptibility was determined by assessing minimum inhibitory concentrations (MIC) of antimicrobial agents. MIC were measured by utility of Agar dilution susceptibility test. RESULTS: Of the total, 38 (13.5%) strains produced beta-lactamase (BLP), 56 (19.9%) strains were beta-lactamase non-producing, ampicillin resistant (BLNAR). The overall resistant proportion to ampicillin was 33.4%. The data indicated that sulbactam/ampicillin, cefotaxime, ceftriaxone and cefditoren are effective against BLP strains. In addition, a high prevalence of BLNAR H. influenzae strains was identified, with an overall isolation rate of 19.9%. Those strains mainly demonstrated intermediate level to ampicillin (ampicillin-MIC 相似文献   

A possible role for lysozyme in determining acute exacerbation in chronic bronchitis.

The aggregation of non-serotypable Haemophilus influenzae (NTHI) by whole saliva from patients with chronic obstructive lung disease (COLD) was investigated. Significant differences were observed between salivary aggregating activity of a control and COLD population (P < 0.001). Saliva from patients less prone to acute exacerbations had a greater capacity to aggregate bacteria compared with saliva from patients with a predilection to infection. The mechanism of saliva-mediated aggregation of NTHI was investigated and shown to be related to lysozyme content. Lysozyme activity in saliva was measured by the turbidimetric technique and results showed that patients with chronic bronchitis had increased levels of salivary lysozyme, with a subpopulation within the non-infection-prone group having greater amounts. A significant difference was observed in salivary lysozyme between controls and non-infection-prone (P < 0.005) and infection-prone (P < 0.05) patients, respectively: the non-infection-prone patients having significantly (P < 0.005) more than the infection-prone patients. There was significant correlation (r = 0.742, P < 0.001) between salivary aggregation of NTHI and lysozyme activity. Chromatographically purified human lysozyme had a similar aggregation profile to that of saliva. There was no difference in serum and saliva lactoferrin concentrations between groups, but there was a significant increase (P < 0.05) in serum lysozyme concentration in the non-infection-prone group. This study suggests that the level of salivary lysozyme derived from macrophages may play an important role in determining resistance or susceptibility to acute bronchitis.     

PCR-based capsular serotype determination of Haemophilus influenzae strains recovered from Japanese paediatric patients with invasive infection

The serotypes of 53 isolates of Haemophilus influenzae from children with invasive infections were determined by a conventional slide agglutination test (SAT) and a recently proposed PCR-based method for serotyping H. influenzae. The PCR assay identified 47 (88.7%) type b isolates, one (1.9%) type e isolate and five (9.4%) non-typeable isolates. The only discrepancy between the methods was an isolate that was non-typeable by SAT, but was identified as serotype e by PCR. Of 41 isolates from patients with meningitis, 39 (95.1%) were type b. Of the five non-typeable isolates, three (60%) were from the blood of patients with septicaemic pneumonia and two (40%) were from the cerebrospinal fluid of patients with meningitis. None of the non-typeable isolates appeared to be a capsule-deficient mutant of an encapsulated H. influenzae strain. Overall, the study confirmed the usefulness of this PCR method for the serotyping of invasive H. influenzae isolates.     

Evaluation of the WIDER I system for antimicrobial susceptibility testing of clinical isolates of Haemophilus influenzae and Streptococcus pneumoniae

The aim of this study was to evaluate the WIDER I system for susceptibility testing of Haemophilus influenzae and Streptococcus pneumoniae . MICs of 12 antimicrobials against 42 H. influenzae and 58 S. pneumoniae strains were determined using 1W MIC panels and compared with those obtained by microdilution. Overall essential agreements were >99%. Very major errors were not detected. Major errors occurred with ampicillin (1.7% H. influenzae ). Minor errors were 2.3% (amoxicillin–clavulanate, cefuroxime, chloramphenicol), 7.1% (ampicillin) and 16.7% (clarithromycin) for H. influenzae , and 1.7% (chloramphenicol, erythromycin, meropenem), 3.4% (amoxicillin–clavulanate, cefuroxime, tetracycline) and 8.6% (levofloxacin) for S. pneumoniae . The WIDER I system is a reliable method for susceptibility testing of H. influenzae and S. pneumoniae .     

Characterization of the antibody response to a Haemophilus influenzae type b conjugate vaccine in children with recurrent lower respiratory tract infection

Children with recurrent lower respiratory tract infection (RLRI) may respond poorly to polysaccharide antigens. To examine how such children respond to a polysaccharide coupled to a protein carrier, we immunized 15 children with RLRI aged 8–69 months and 15 carefully age-matched healthy controls once with a Haemophilus influenzae type b (Hib) conjugate vaccine. Total IgG subclasses, total antipolysaccharide Hib antibodies, and antipolysaccharide Hib antibodies of IgM, IgG, IgA, and IgG 1–4 specificity were determined by ELISA. There were no significant differences between the two groups in any single total IgG subclass, but total IgG measured as the sum of all four subclasses was significantly lower in the children with RLRI than in the controls ( P = 0.036). Before vaccination, the children with RLRI had significantly less IgG antipolysaccharide Hib antibody than the controls ( P = 0.005), whereas 1 month later they had significantly more IgM antibody (P = 0.038). No other significant differences were found between the groups before or after immunization with respect to antipolysaccharide Hib antibodies. Since naturally occurring IgG antibodies are thought to be aquired partly as a consequence of antigenic stimulation on mucosal surfaces, we hypothesize that the low level of specific IgG found before immunization, as well as the low total IgG in the children with RLRI, may reflect an impaired ability to prime through mucosal surfaces. This is supported by our finding of an increased IgM response to Hib conjugate vaccine in these children, since this isotype predominates in the primary immune response, i.e., in the absence of immunologic memory. In conclusion, children with RLRI can be protected against invasive Hib infection as well as healthy children, but may have an immunodeficiency characterized by defective ability to respond to antigenic stimulation on mucosal surfaces.     

Risk factors in HIV-1-infected patients developing repetitive bacterial infections: toxicological,clinical, specific antibody class responses,opsonophagocytosis and Fc(gamma) RIIa polymorphism characteristics

The aim of the study was to determine possible factors related to the risk of developing recurrent bacterial respiratory tract infections in HIV-1-infected patients, regardless of the degree of immune cellular impairment. Thirty-three HIV-1 seropositive patients with previous repetitive bacterial respiratory tract infections (case group), 33 HIV-1 seropositive controls (matched by CD4-cell counts) without these antecedents and 27 healthy controls were studied before and after administration of pneumococcal and Haemophilus influenzae type b vaccines. Clinical or toxicological variables, cutaneous tests, complement factors, beta2-microglobulin, serum IgM, IgA, IgG and subclasses, specific antibodies (IgG, IgG2, IgA) against pneumococcal vaccine and polyribosylribitol phosphate (PRP), their avidity, opsonophagocytosis and IgG(2)m and Fc(gamma)RIIa allotypes were determined. A history of drug abuse (P = 0.001), less likelihood of receiving high activity antiretroviral treatment high activity antiretroviral treatment (HAART) (P = 0.01), higher levels of HIV-1 viral load (P < 0.05), serum IgG (P < 0.01) and beta2-microglobulin (P < 0.01) were observed in the case group. Also, a lower increase in specific antibodies to pneumococcal vaccine and PRP was demonstrated in the cases in comparison with the two control groups. No differences were observed in the avidity of antibodies, opsonophagocytic capacity or IgG(2)m and Fc(gamma)RIIa allotypes between the three groups. These data indicate that vaccination strategies against encapsulated bacteria can be unsuccessful in the HIV-1-infected patients presenting repetitive bacterial respiratory tract infections if behavioural aspects or measures to improve adherence to HAART therapies are not considered.     

海口市儿童肺炎患者呼吸道标本流感嗜血杆菌的耐药性与分子流行病学特征

 目的 调查海口市肺炎患儿分离的流感嗜血杆菌临床分布、耐药状况及克隆传播情况,为预防和治疗儿童流感嗜血杆菌性肺炎提供理论依据。方法 收集2021年海口市妇幼保健院5 342例住院肺炎患儿临床资料,分析患儿呼吸道标本流感嗜血杆菌阳性情况,检测菌株耐药性,并采用多位点序列分型（MLST）分析其同源性。结果 5 342例肺炎患儿共分离352株流感嗜血杆菌,检出率为6.59%;男患儿检出率为7.10%,女患儿检出率为5.82%;年龄<30 d检出率为0.30%,30 d~为8.45%,2岁~为11.62%,4岁~为12.88%,≥ 6岁为2.56%,各年龄段检出率比较差异有统计学意义（P<0.05）;春季检出率为14.04%,夏季为4.48%,秋季为4.62%,冬季为4.40%,各季节检出率比较差异有统计学意义（P<0.001）。流感嗜血杆菌β-内酰胺酶阳性率为42.60%（141/331）,对复方磺胺甲口恶唑、氨苄西林、头孢呋辛的耐药率分别为76.43%、69.19%、51.36%,对阿奇霉素、阿莫西林/克拉维酸、头孢他啶和头孢曲松的耐药率<30%,对美罗培南和左氧氟沙星的耐药率<1%。51株流感嗜血杆菌经MLST测序分成15个ST型;其中ST107包含11株（21.57%）,主要分布在4个月~1岁患儿（9株）和3岁患儿（2株）。结论 海口市肺炎患儿分离的流感嗜血杆菌具有遗传多样性,且发生社区克隆传播,以2~3岁幼儿感染多见。春季是感染高发季节,ST107是春季流行优势克隆型。经验治疗时须谨慎使用复方磺胺甲口恶唑、氨苄西林和头孢呋辛,阿莫西林/克拉维酸耐药率和β-内酰胺酶阴性菌株对氨苄西林耐药率升高,临床应引起重视。     

小儿化脓性中耳炎的病原学调查

目的　调查小儿化脓性中耳炎的主要病原菌及其对抗生素的耐药情况。方法　对 5 2例化脓性中耳炎患儿的中耳分泌物进行细菌培养 ,每份标本分别用 5 %～ 7%羊血平板和自制改良巧克力平板分离 ,置烛缸培养。对获得的病原菌用K -B纸片琼脂扩散法行药物敏感试验。结果　分离出 46株致病菌 ,嗜血杆菌 (15株 )和金黄色葡萄球菌为主 ,嗜血杆菌对青霉素和复方新诺明的耐药率分别为 83.3%和 40 % ,以金黄色葡萄球菌为主的临床常见菌对氨苄青霉素和氧哌嗪青霉素的耐药率分别为 95 .5 %和 5 4.2 %。结论　嗜血杆菌和金黄色葡萄球菌是本地区小儿化脓性中耳炎的主要致病菌 ,两者对青霉素类抗生素的耐药率皆较高。     

Effect of aluminum adjuvants on safety and immunogenicity of Haemophilus influenzae type b-CRM197 conjugate vaccine

OBJECTIVE: The present study was carried out to evaluate the safety and immunogenicity of the Haemophilus influenzae type b-CRM197 (Hib-CRM197) conjugate vaccine in relation to the change of adjuvant from aluminum hydroxide to aluminum phosphate (AlPO4). METHODS: The present study was a clinical phase II, observer-blind, randomized, multicenter, controlled study. Subjects were healthy infants aged 6-12 weeks, eligible for expanded program of immunization (EPI) routine vaccination and admitted to Hacettepe University Department of Social Pediatrics and Gülveren Health Center, Ankara. A total of 520 healthy infants were randomized in a 2:2:1 ratio to receive at either Chiron Hib/AlPO4 vaccine or VaxemHib (aluminum hydroxide adjuvant) vaccine or HibTiter (no adjuvant). Vaccines were administered simultaneously with routine diphtheria, tetanus and pertussis (DTaP) and oral polio vaccine (OPV) vaccines at 2, 4 and 6 months of age. Blood samples for anti-plain polysaccharide (PRP) antibody measurement were collected before the first vaccination and 1 month after the last vaccination. After each vaccination parents filled out a diary for 7 days. RESULTS: Out of 520 subjects enrolled, 514 received three doses and were included for safety analysis. Local and systemic reactions occurred with low and similar frequencies in all groups. Only erythema was more common in Chiron Hib/AlPO4 vaccine (19, 10, 11% in Chiron Hib/AlPO4, VaxemHib and HibTiter, respectively, P < 0.05). Nine serious adverse events were reported in seven cases of which none were related to vaccines. A total of 504 subjects were included in the immunogenicity analysis. The three vaccines were highly immunogenic and equivalent in terms of percentage of acquisition of long-term protective levels. The anti-PRP geometric mean titers were 9.9, 8.3 and 5.14 micro g/mL, respectively (P < 0.05). CONCLUSIONS: The use of aluminum compounds adjuvants in Hib-CRM197 conjugate vaccines does not impact the safety profile, while it does increase the magnitude of anti-PRP antibody titers.