Adolescent ; Child ; Child, Preschool ; China ; epidemiology ; Drug Resistance, Bacterial ; Female ; Humans ; Infant ; Male ; Moraxella (Branhamella) catarrhalis ; drug effects ; Prevalence ; Respiratory Tract Infections ; epidemiology ; microbiology

OBJECTIVETo investigate the prevalence of Moraxella catarrhalis in the nasopharyngeal region of children with respiratory infection and the sensitivity of Moraxella catarrhalis isolates to common antimicrobial drugs.

METHODSNasopharyngeal swabs were collected from 1 082 children with respiratory infection, and Moraxella catarrhalis strains were isolated. The E-test method and disc diffusion test were used to determine the sensitivity of these strains to 11 common antimicrobial drugs. The test results were interpreted with reference to the standards of European Committee on Antimicrobial Susceptibility Testing (EUCAST), Clinical and Laboratory Standards Institute (CLSI), and British Society for Antimicrobial Chemotherapy (BSAC). The nitrocefin disc method was used to detect whether the isolated strains produced β-lactamase.

RESULTSAmong the 1 082 children with respiratory infection, 77 (77/1 082, 7.12%) carried Moraxella catarrhalis in the nasopharyngeal region. All the strains produced β-lactamase. With reference to all the three standards, all the strains were sensitive to amoxycillin-clavulanate and had a susceptibility rate of >95% towards ciprofloxacin and tetracycline. According to the EUCAST and CLSI standards, the susceptibility rate of the strains towards sulfamethoxazole-trimethoprim was as high as 98.7%, and more than 80% of all strains were sensitive to the three cephalosporins detected; however, with reference to the BSAC standard, only 2.6% of the strains were sensitive to cefuroxime, with an intermediate rate of 44.2% and a drug resistance rate of 53.2%. The rate of resistance to ampicillin was 81.8%. According to the CLSI standard, the non-susceptibility rate of the strains to erythromycin was 79.2%, and according to the EUCAST or BSAC standards, their non-susceptibility rate reached 90.9%; more than one third of the strains (27/77, 35.1%) had a minimal inhibitory concentration of >256 mg/L.

CONCLUSIONSAll of the Moraxella catarrhalis isolates in the nasopharyngeal region of children with respiratory infection produce β-lactamase and are sensitive to amoxycillin-clavulanate. These isolates have high susceptibility rates to the third- and fourth-generation cephalosporins and sulfamethoxazole-trimethoprim, but most of the isolates are resistant to ampicillin, cefuroxime, and erythromycin.

Adolescent ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Humans ; Infant ; Male ; Microbial Sensitivity Tests ; Moraxella (Branhamella) catarrhalis ; drug effects ; isolation & purification ; Nasopharynx ; microbiology ; Respiratory Tract Infections ; microbiology

Gemifloxacin is an enhanced-affinity fluoroquinolone with broad-spectrum antibacterial activity. In Korea, resistant bacteria are relatively more prevalent than in other industrialized countries. In this study, we studied the in vitro activities of gemifloxacin, gatifloxacin, moxifloxacin, levofloxacin, ciprofloxacin, and other commonly used antimicrobial agents against 1,689 bacterial strains isolated at four Korean university hospitals during 1999-2000. Minimum inhibitory concentrations (MICs) were determined using the agar dilution method of National Committee for Clinical Laboratory Standards. Gemifloxacin had the lowest MICs for the respiratory pathogens: 90% of Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae were inhibited by 0.06, 0.03, and 0.03 mg/L, respectively. Gemifloxacin was more active than the other fluoroquinolones against methicillin-susceptible Staphylococcus aureus, coagulase-negative staphylococci, streptococci, and Enterococcus faecalis. The MIC90s of gemifloxacin for Klebsiella oxytoca, Proteus vulgaris, and nontyphoidal Salmonella spp. were 0.25, 1.0, and 0.12 mg/L, respectively, while those for other Gram-negative bacilli were 4-64 mg/L. In conclusion, gemifloxacin was the most active among the comparative agents against Gram-positive species, including respiratory pathogens isolated in Korea.
Anti-Infective Agents/*therapeutic use ; *Aza Compounds ; Bacteria/*drug effects ; Ciprofloxacin/therapeutic use ; *Fluoroquinolones ; Haemophilus influenzae/drug effects ; Korea ; Microbial Sensitivity Tests ; Moraxella/drug effects ; Naphthyridines/*therapeutic use ; Ofloxacin/therapeutic use ; *Quinolines ; Streptococcus pneumoniae/drug effects