Evaluation of
bla
OXA-48-like
point mutation carbapenemase-producing
Enterobacterales
in Prapokklao Hospital, Thailand
Authors: Santajit Sirijan , Tunyong Witawat , Kong-Ngoen Thida , Arsheewa Weewan , Hinthong Woranich , Pumirat Pornpan , Sookrung Nitat , Indrawattana Nitaya 
Published: October 2024

Carbapenemase-producing
Enterobacterales
(CPE) isolates increasingly carry oxacillinase-48 (OXA-48)-like enzymes encoded by
bla
OXA-48-like
, which can confer high levels of carbapenem resistance. This aims to determine the prevalence of CPE and genetic variation among
bla
OXA-48-like
-carrying isolates recovered from Prapokklao Hospital in Chanthaburi Province, Thailand in 2016–2017. In total, 122 carbapenem-resistant
Enterobacterales
(CRE) isolates were recovered from clinical samples. CRE were evaluated using standard biochemical tests and MIC test strips. Carbapenemase production was assessed through the modified Hodge test (MHT), modified carbapenem inactivation method (mCIM), and EDTA-modified carbapenem inactivation method (eCIM). Detection of
bla
OXA-48-like
mutations was conducted via PCR and confirmed by Sanger sequencing. Among these CRE isolates, 72 (59.02%), 44 (36.07%), 3 (2.46%), and 3 (2.46%) were
Klebsiella pneumoniae
,
Escherichia coli
,
Enterobacter aerogenes
, and
Enterobacter cloacae
, respectively. The MHT identified carbapenemase production in 108 isolates (88.52%). Based on the mCIM, 81 isolates (66.39%) were carbapenemase producers. Seventy-three isolates (59.84%) were eCIM-positive, indicating metallo-β-lactamase production. Three distinct genetic variants of the
bla
OXA-48-like
gene were identified among the isolates, including the wild-type and two point mutation types harboring the mutations E168Q and S171A (mutation type 1) and E168Q, S171A, and R214S (mutation type 2). Multiple-sequence alignment and
in silico
analysis revealed variation of R214 located in the β5–β6 loop. This study identified
bla
OXA-48-like
point mutation groups and carbapenemase production, predominantly metallo-β-lactamases, among CRE isolates, especially
K. pneumoniae
and
E. coli
. These findings highlight the importance of implementing stringent infection control measures and active antimicrobial resistance surveillance to combat the spread of difficult-to-treat, metallo-β-lactamase-producing CRE in healthcare settings.

IMPORTANCE

In this study, we aimed to investigate genetic variation and CPE among bla
OXA-48-like
carrying isolates recovered from Prapokklao Hospital, Chanthaburi Province, Thailand, during 2016–2017. A total of 122 carbapenem-resistant Enterobacterales (CRE) were recovered from clinical samples in Prapokklao Hospital. All CRE samples were confirmed by standard biochemical tests and minimum inhibitory concentration (MIC) test strips (E-test). The carbapenemase production was determined using the modified Hodge test (MHT), the modified carbapenem inactivation method (mCIM), and EDTA-CIM (eCIM). Three single mutations (E168Q, S171A, and R214S) were characterized in this study. This mutation might reflect the hydrolysis of the modified β-lactam spectrum, especially carbapenem, by OXA-48-like. Our report provides evidence of the bla
OXA-48-like
point mutation and carbapenemase-producing phenotype of CRE detected in this healthcare setting. Effective control measures and active surveillance of drug resistance in nosocomial pathogens are crucial for controlling diseases associated with difficult-to-treat bacteria.