Massive Spread of OXA-48 Carbapenemase-Producing Enterobacteriaceae in the Environment of a Swiss Companion Animal Clinic

Dynamics of blaOXA-23 gene transmission in Acinetobacter spp. from contaminated veterinary environmental surfaces: an emerging One Health threat?

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii is a common pathogen associated with healthcare-acquired infections, and robust infection prevention and control protocols exist in human healthcare settings. In contrast, infection prevention and control (IPC) standards are limited in veterinary medicine, necessitating further investigation.

AIM

Examine the possible transmission of carbapenem-resistant Acinetobacter spp. in a veterinary practice where a cat was diagnosed with an OXA-23-producing A. baumannii ST2 strain.

METHODS

Environmental samples together with nasal and hand swabs from the veterinary personnel were collected. All swabs were screened for the presence of extended-spectrum-β-lactamase- and carbapenemase-producing Enterobacterales, meticillin-resistant staphylococcus and multi-drug-resistant Acinetobacter spp. Whole-genome sequencing was performed for carbapenemase-producing strains.

RESULTS

Of the veterinary staff, 60% carried meticillin-resistant Staphylococcus epidermidis. Environmental evaluation showed that 40% (N=6/15) of the surfaces analysed by contact plates and 40% (N=8/20) by swabs failed the hygiene criteria. Assessment of the surfaces revealed contamination with five OXA-23-producing Acinetobacter spp. strains: an OXA-23-producing Acinetobacter schindleri on the weight scale in the waiting room; and four OXA-23-producing Acinetobacter lwoffii strains, on different surfaces of the treatment room. The blaOXA-23 gene was located on the same plasmid-carrying Tn2008 across the different Acinetobacter spp. strains. These plasmids closely resemble a previously described OXA-23-encoding plasmid from a human Portuguese nosocomial Acinetobacter pittii isolate. Distinctly, the OXA-23-producing A. baumannii ST2 clinical strain had the resistant gene located on Tn2006, possibly inserted on the chromosome.

CONCLUSION

The detection of an OXA-23-producing A. baumannii ST2 veterinary clinical strain is of concern for companion animal health and infection, prevention and control. This study established the dynamic of transmission of the plasmid-mediated blaOXA-23 gene on critical surfaces of a small animal veterinary practice. The genetic resemblance to a plasmid found in human nosocomial settings suggests a potential One Health link.

Emergence of OXA-48-producing Enterobacter hormaechei in a Swiss companion animal clinic and their genetic relationship to clinical human isolates

BACKGROUND

Enterobacter hormaechei producing the carbapenemase OXA-48 was identified repeatedly in infections in companion animals hospitalized at a Swiss veterinary clinic where OXA-48-producing Klebsiella pneumoniae was previously reported.

OBJECTIVES

To determine the genetic relatedness of animal and human E. hormaechei strains collected in Switzerland during 2017-22 and their mobile genetic elements.

METHODS

Hybrid assemblies for phylogenetic and comparative analysis of animal (n = 9) and human (n = 25) isolates were obtained by sequencing with Illumina, PacBio and Oxford Nanopore Technologies. Antimicrobial susceptibility was tested by broth microdilution.

RESULTS

The animal strains were identified as E. hormaechei subsp. xiangfangensis ST114 (n = 6) and ST418 (n = 2), and E. hormaechei subsp. hoffmannii ST78 (n = 1). Human E. hormaechei belonged to subspecies steigerwaltii (n = 10), xiangfangensis (n = 13), hoffmannii (n = 1) and hormaechei (n = 1), with a heterogeneous ST distribution differing from the animal strains, except for two ST114. Core-gene SNP analysis confirmed the clonality of the animal ST114 and ST418 isolates (0 to 10 SNPs), and close relatedness of animal and human ST114 strains (80-120 SNPs). The strains harboured the blaOXA-48 gene on ca. 63 kb IncL-type plasmids (n = 27); on ca. 72 kb IncL plasmids co-harbouring blaCTX-M-14 (n = 2); and on ca. 150-180 kb IncFIB (n = 4) or hybrid IncFIB/IncL (n = 1) plasmids. The blaOXA-48-harbouring plasmids and the blaDHA-1-carrying ISCR1 element in one animal ST114 and both ST418 clones were likely acquired from previously spreading K. pneumoniae strains.

CONCLUSIONS

Common ecological niches favour the spread of plasmid-borne carbapenemases among Enterobacterales and the emergence of MDR E. hormaechei clones.

Educational intervention to improve infection prevention and control practices in four companion animal clinics in Switzerland

BACKGROUND

Infection prevention and control (IPC) practices vary among companion animal clinics, and outbreaks with carbapenemase-producing Enterobacterales (CPE) have been described.

AIM

To investigate the effect of an IPC intervention (introduction of IPC protocols, IPC lectures, hand hygiene campaign) in four companion animal clinics.

METHODS

IPC practices, environmental and hand contamination with antimicrobial-resistant micro-organisms (ARM) and hand hygiene (HH) were assessed at baseline, and 1 and 5 months after the intervention.

RESULTS

Median IPC scores (% maximum score) improved from 57.8% (range 48.0-59.8%) to 82.9% (range 81.4-86.3%) at 1-month follow-up. Median cleaning frequency assessed by fluorescent tagging increased from 16.7% (range 8.9-18.9%) to 30.6% (range 27.8-52.2%) at 1-month follow-up and 32.8% (range 32.2-33.3%) at 5-month follow-up. ARM contamination was low in three clinics at baseline and undetectable after the intervention. One clinic showed extensive contamination with ARM including CPE before and after the intervention (7.5-16.0% ARM-positive samples and 5.0-11.5% CPE-positive samples). Mean HH compliance improved from 20.9% [95% confidence interval (CI) 19.2-22.8%] to 42.5% (95% CI 40.4-44.7%) at 1-month follow-up and 38.7% (95% CI 35.7-41.7%) at 5-month follow-up. Compliance was lowest in the pre-operative preparation area at baseline (11.8%, 95% CI 9.3-14.8%) and in the intensive care unit after the intervention (28.8%, 95% CI 23.3-35.1%). HH compliance was similar in veterinarians (21.5%, 95% CI 19.0-24.3%) and nurses (20.2%, 95% CI 17.9-22.7%) at baseline, but was higher in veterinarians (46.0%, 95% CI 42.9-49.1%) than nurses (39.0%, 95% CI 36.0-42.1%) at 1-month follow-up.

CONCLUSION

The IPC intervention improved IPC scores, cleaning frequency and HH compliance in all clinics. Adapted approaches may be needed in outbreak situations.

OXA-48-Like β-Lactamases: Global Epidemiology, Treatment Options, and Development Pipeline

Modern medicine is threatened by the rising tide of antimicrobial resistance, especially among Gram-negative bacteria, where resistance to β-lactams is most often mediated by β-lactamases. The penicillin and cephalosporin ascendancies were, in their turn, ended by the proliferation of TEM penicillinases and CTX-M extended-spectrum β-lactamases. These class A β-lactamases have long been considered the most important. For carbapenems, however, the threat is increasingly from the insidious rise of a class D carbapenemase, OXA-48, and its close relatives. Over the past 20 years, OXA-48 and "OXA-48-like" enzymes have proliferated to become the most prevalent enterobacterial carbapenemases across much of Europe, Northern Africa, and the Middle East. OXA-48-like enzymes are notoriously difficult to detect because they often cause only low-level in vitro resistance to carbapenems, meaning that the true burden is likely underestimated. Despite this, they are associated with carbapenem treatment failures. A highly conserved incompatibility complex IncL plasmid scaffold often carries bla_OXA-48 and may carry other antimicrobial resistance genes, leaving limited treatment options. High conjugation efficiency means that this plasmid is sometimes carried by multiple Enterobacterales in a single patient. Producers evade most β-lactam-β-lactamase inhibitor combinations, though promising agents have recently been licensed, notably ceftazidime-avibactam and cefiderocol. The molecular machinery enabling global spread, current treatment options, and the development pipeline of potential new therapies for Enterobacterales that produce OXA-48-like β-lactamases form the focus of this review.