Molecular and Drug Resistance Characteristics of Carried by Pediatric Patients with Adenoid Hypertrophy.

PURPOSE

The adenoid microbiota plays a key role in adenoid hypertrophy (AH). This study explored the molecular epidemiology and antimicrobial resistance of () strains in pediatric AH patients.

METHODS

Retrospective analysis of pediatric AH patients undergoing endoscopic adenoidectomy. Adenoid tissue samples were cultured to screen for pathogens. strains were identified by 16S rRNA sequencing and serotyped via q-PCR. Multilocus sequence typing (MLST) and ftsI gene analysis were conducted using PubMLST. β-lactamase genes (, ) were detected by PCR, and antibiotic susceptibility testing (AST) was performed using the Etest method. For imipenem-resistant strains, the acrRAB efflux pump gene cluster and ompP2 porin gene were sequenced and compared with those of the wild-type strain Rd KW20.

RESULTS

Over 8 months, 56 non-duplicate strains were isolated from 386 patients. The detection rate was highest in children under 5 years (30.5%) compared to those aged 5-10 years (13.4%) and 10-15 years (8.7%). Of 49 sub-cultured strains, all were non-typeable (NTHi). MLST identified 22 sequence types (STs) and 13 clonal complexes (CCs), with CC11 (26.5%), CC3 (14.3%), and CC107 (14.3%) being predominant. Common STs included ST103 (22.4%), ST57 (10.2%), and ST107 (10.2%). Most strains belonged to the ftsI group III-like+ (57.1%). β-lactamase positivity was 98.0% (48/49), with (95.9%) and (18.4%) detected. AST showed low susceptibility to ampicillin (10.2%), amoxicillin-clavulanate (34.7%), azithromycin (12.2%), and trimethoprim-sulfamethoxazole (14.3%). Among the β-lactamase-positive strains, 44/48 were β-lactamase-positive ampicillin-resistant (BLPAR); none were β-lactamase-negative ampicillin-resistant (BLNAR). Imipenem susceptibility was 91.8% (45/49). No carbapenemases were found in the imipenem-resistant strains, but mutations in acrRAB (88.12-94.94% identity) and ompP2 (77.10-82.94% identity) were observed.

CONCLUSIONS

BLPAR NTHi strains of CC11 are major epidemic strains in pediatric AH. Imipenem resistance in likely results from porin mutations rather than carbapenemase activity. Enhanced surveillance of 's role in AH and its resistance patterns is warranted.