Prevalence and molecular characteristics of β-lactam resistance in non-typeable Haemophilus influenzae isolates in Korea
- Author:
Eun-Young KIM
1
;
Yeon Chan CHOI
;
Hyeon Jin CHOI
;
Si Hyun KIM
;
Jihyun CHO
;
Seok Hoon JEONG
;
Dokyun KIM
;
Hyun Soo KIM
;
Soo Hyun KIM
;
Young Ah KIM
;
Young Ree KIM
;
Nam Hee RYOO
;
Jong Hee SHIN
;
Kyeong Seob SHIN
;
Young UH
;
Jeong Hwan SHIN
Author Information
- Publication Type:Original article
- From:Annals of Clinical Microbiology 2025;28(4):23-
- CountryRepublic of Korea
- Language:English
-
Abstract:
Background:Haemophilus influenzae is the causative pathogen for various infectious diseases, such as respiratory infections, otitis media, sinusitis, and meningitis. This study aimed to investigate the prevalence and molecular characteristics of β-lactam resistance in non-typeable H. influenzae isolates in South Korea.
Methods:In total, 115 non-duplicated H. influenzae isolates were included in this study.Bacterial identification and serotyping were performed using matrix assisted laser desorption ionization-time of flight mass spectrometry and polymerase chain reaction (PCR) of bexA, respectively. Antimicrobial susceptibility was tested using the broth microdilution method.The production of β-lactamase was determined using nitrocefin disks. The presence of blaTEM and blaROB was confirmed using PCR. ftsI was analyzed to identify amino acid mutations in penicillin-binding protein (PBP) 3.
Results:Resistance rates to ampicillin, amoxicillin–clavulanate, and cefuroxime were 67.8%, 13.9%, and 32.2%, respectively. None of the isolates were resistant to cefotaxime or ceftriaxone. Among 78 ampicillin-resistant isolates, 71 were β-lactamase-producing ampicillinresistant (BLPAR), and 7 were β-lactamase-non-producing ampicillin-resistant. All BLPAR isolates carried blaTEM, and none carried blaROB. Among 16 amoxicillin–clavulanate-resistant isolates, 15 β-lactamase producers harbored blaTEM. Four to 7 PBP3 mutations per isolate were detected in all 16 non-β-lactamase-producing ampicillin-resistant or cephalosporinresistant isolates.
Conclusion:Beta-lactam resistance in non-typeable H. influenzae isolates is highly prevalent in South Korea, primarily because of blaTEM and various PBP3 mutations. Therefore, continuous monitoring of antimicrobial resistance rates and mechanisms in non-typeable H.influenzae is necessary.
