Antimicrobial Resistance in Haemophilus influenzae Respiratory Tract Isolates in Korea: Results of the Nationwide Acute Respiratory Infections Surveillance. Antimicrobial agents and chemotherapy [Antimicrob Agents Chemother] Journal article

Antimicrobial susceptibility patterns and beta-lactam resistance mechanisms of 544 H. influenzae isolates through the nationwide Acute Respiratory Infections Surveillance (ARIS) network in Korea during 2005 and 2006 were determined. Resistance to ampicillin was 58.5%, followed by cefuroxime (23.3%), clarithromycin (18.7%), cefaclor (17.0%), amoxicillin/clavulanate (10.4%), and chloramphenicol (8.1%). Levofloxacin and cefotaxime were the most active agents tested in this study. beta-lactamase production (52.4%) was the main mechanism of ampicillin resistance, with the rate (96.1%) of TEM-1 type beta-lactamase. According to their beta-lactam resistance mechanisms, all isolates were classified into the following groups: beta-lactamase-negative, ampicillin-sensitive (BLNAS) strains (n= 224; 41.5%); beta-lactamase-positive, ampicillin-resistant (BLPAR) strains (n = 255; 47.2%); beta-lactamase-negative, ampicillin-resistant (BLNAR) strains (n = 33; 6.1%); and beta-lactamase-positive, amoxicillin/clavulanate-resistant (BLPACR) strains (n = 28; 5.2%). Among the BLNAR and BLPACR strains, there were various patterns of multiple amino acid substitutions in penicillin binding protein 3. Particularly, among BLNAR, group III isolates, which had three simultaneous substitutions (Met377Ile, Ser385Thr, and Leu389Phe) were identified for the first time in Korea. Three group III strains displayed the highest minimum inhibitory concentration of cefotaxime (1-2 mug/ml). The results indicate the importance of monitoring a changing situation pertaining to the increase and spread of BLNAR and BLPACR strains of H. influenzae for appropriate antibiotic therapy for patients with RTIs in Korea.

Antimicrobial agents and chemotherapy [Antimicrob Agents Chemother]