Molecular characterization of Carbapenem-resistant Gram-negative bacilli associated with nosocomial infections in Hail, Saudi Arabia

BACKGROUND:
Carbapenem-resistant Enterobacteriaceae (CRE) are listed as critical priority antibiotic-resistant pathogens by the World Health Organization.


OBJECTIVE:
This study investigated the prevalence and the molecular mechanisms underlying carbapenem resistance among four clinically relevant Gram-negative bacterial species associated with nosocomial infections.


DESIGN:
Single-centre cross-sectional study


SETTING:
A tertiary hospital in Hail, Saudi Arabia


METHODS:

A total of 207 nosocomial gram-negative bacilli isolates were collected from December 2022 to July 2023. The isolates’ identification and antimicrobial susceptibility testing (AST) were done using BD Phoenix M50. Isolates that showed resistance to one or more Carbapenemes agents in the antibiotic susceptibility test (AST) profile were further tested by a molecular method using Polymerase Chain Reaction (PCR) (Xpert Carba-R assay) for the detection of five most common Carbapenemases [
K. pneumoniae
carbapenemase (KPC), imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), the New Delhi metallo-β-lactamase (NDM) and oxacillinase (OXA-14)].



MAIN OUTCOME MEASURES:
Identification of carbapenemase producers among Gram-negative bacteria associated with nosocomial infections.


SAMPLE SIZE:
207 Gram-negative bacilli isolates


RESULTS:

Of 207 GNB isolates, 162 were carbapenem-resistant, with
Klebsiella pneumoniae
being the most prevalent isolates (n=59), followed by
Acinetobacter baumannii
(n=55),
P. aeruginosa
(n=34), and Proteus mirabilis (n=14). At least one carbapenemase gene was detected in 65 isolates, where
K. pneumoniae
has the highest rate with (n=43) followed by
A. baumannii
(n=9),
P. aeruginosa
(n=8), and
P. mirabilis
(n=5). The most predominant carbapenemase gene was bla
OXA-48
with 70.8% (n=46), followed by bla
NDM
with 15.4% (n=10) and 13.8% (n=9) co-harboring bla
OXA-48
and bla
NDM
.



CONCLUSION:

Carbapenemase-producing Gram-negative bacilli were prevalent among hospitalized patients in Hail, with bla
OXA-48
and blaNDM detected primarily in
K. pneumoniae
. Whole genome sequencing (WGS) is recommended to identify dominant nosocomial clones in the region.



LIMITATIONS:
The lack of sufficient funding has impeded the expansion of this study to perform WGS on all isolates.