Expression of ESBL-Like Activity in Infrequently Encountered Members of the Family Enterobacteriaceae

Genomic insights into Leminorella grimontii and its chromosomal class A GRI β-lactamase

Leminorella grimontii strain LG-KP-E1-2-T0 was isolated from Zophobas morio larvae. It showed a susceptibility phenotype compatible with the expression of an inducible extended-spectrum β-lactamase. The presence of a chromosomal bla gene encoding for the class A GRI-1 β-lactamase was revealed by whole-genome sequencing. GRI-1 shared the highest amino acid identity with RIC-1 and OXY-type β-lactamases (76-80%). Analysis of six further publicly-available L. grimontii draft genomes deposited in NCBI revealed that blaGRI-1 was always present. Core-genome analysis indicated that LG-KP-E1-2-T0 was unique from other strains. We provided the first complete genome of L. grimontii and new insights on its chromosomal β-lactamases.

Epidemiological characteristics of Klebsiella ozaenae infection and its antibiotic susceptibility: Experience of a tertiary care hospital in the Eastern Province of Saudi Arabia

BACKGROUND

Klebsiella ozaenae (K. ozaenae), a forgotten pathogen that normally colonizes the upper respiratory mucosa, can be associated with severe and invasive infections. The objectives of this study were to determine the frequency of isolation of K. ozaenae at the microbiology laboratory in a tertiary hospital and the scope of diseases associated with it and to characterize its antimicrobial susceptibility pattern.

MATERIALS AND METHODS

This cross-sectional study analyzed the retrospective data, from 2002 to 2021, on cases with laboratory-confirmed isolation of K. ozaenae at a tertiary care hospital. The primary outcome was to identify the scope of K. ozaenae infections and their antimicrobial susceptibility patterns. K. ozaenae isolation was done by cultivation on microbiological culture media, whereas its identification and antimicrobial susceptibility pattern were performed using either Microscan or Vitek automated systems. Data was gathered and analyzed in Excel. The percentage of resistance was calculated as the number of resistant isolates from the total isolates multiplied by 100. Similarly, the percentage of sensitivity was calculated as the number of sensitive isolates from total isolates multiplied by 100.

RESULTS

K. ozaenae was detected in 59 cases during the study period. K. ozaenae was associated with urinary tract infections (39%), nasal infections (18.6%), other respiratory tract infections including sinusitis, bronchiectasis, and pneumonia (16.9%), and wound infections (15.3%). It was also associated with invasive infections such as bacteremia (3.4%) and abscesses (3.4%). K. ozaenae showed susceptibility to multiple antibiotic classes, but was resistant to ampicillin, piperacillin, nalidixic acid, and nitrofurantoin. K. ozaenae isolates from urinary tract infections had higher antibiotic resistance percentage than isolates from other infections, particularly to amoxicillin/clavulanic acid (P = 0.007, 95% confidence interval [CI]: 1.84-375), ciprofloxacin (P < 0.0001, 95% CI: 4.6-111.2), and trimethoprim/sulfamethoxazole (P < 0.001, 95% CI: 3.1-63.6).

CONCLUSION

Our data show that K. ozaenae is a pathogen with a spectrum of diseases wider than expected and a unique antibiotic susceptibility pattern in urinary tract infections.

Extended spectrum beta-lactamase testing of community Enterobacteriaceae in the west of Australia: poor performance of phenotypic methods

Expanded spectrum β-lactamase (ESBL) producing organisms have long been recognised in institutions worldwide. Recently, community isolates producing ESBL have been reported overseas and in eastern Australia. We tested 571 consecutive Enterobacteriaceae urinary isolates from Western Australia and the Northern Territory phenotypically by calibrated dichotomous sensitivity (CDS) methods in two periods (2007 and 2012). Eleven ESBL-producing isolates from 2012 and 39 banked strains were genotyped by PCR. Twenty-six (4.6%) strains produced ESBL by CDS. Only 57.7% of CDS-confirmed ESBL strains had an initial reduced cephalosporin zone. Vitek 2 identified only nine (34.6%) CDS-ESBL strains. There was no significant change in ESBL strain prevalence over the two periods by CDS, but our laboratory information system showed a steady increase from 2007-2012 in ESBL strain prevalence (identified by multiple methods) at a rate of 0.02% per month to reach 2% by 2012. Genotyping of 50 CDS-confirmed isolates demonstrated ESBL genes in 44 (88%), mainly CTX-M genes. Twenty-five ESBL strains contained more than one β-lactamase gene, up to a maximum of three genes. There is a rising prevalence of ESBL strains in our communities. CDS and Vitek-2 testing is neither sensitive nor specific in detecting ESBL enzymes. Routine laboratories need access to genotyping to identify and monitor ESBLs in the community.