Plasmid-mediated MCR-5 gene detected in isolates from Chinese pigs
Chinese and Swedish researchers have detected the colistin resistance gene MCR-5 in an Aeromonas hydrophila isolate from pigs in rural China, according to a study today in the Journal of Antimicrobial Chemotherapy.
The MCR-5-harboring isolate was found among fecal samples collected from backyard pigs from 194 households in rural areas of Shandong Province in August 2017. The identified isolate, I064-2, was resistant to colistin and displayed intermediate susceptibility to tetracycline, but was susceptible to several other antibiotics, including amikacin, gentamicin, ciprofloxacin, and meropenem.
Whole-genome sequencing of the isolate confirmed that the MCR-5 gene was located on a plasmid with genetic features similar to those found in other Aeromonas species, Enterobacteriaceae, and Pseudomonas species, a finding that suggests the possibility of horizontal transfer of the MCR-5-carrying segment among these bacterial species and genera.
Bacteria belonging to the Aeromonas genus cause diarrheal diseases and wound infections in humans and animals. Prior to this study, the MCR-5 gene had only been found in Salmonella spp. from poultry- and animal-derived food products in Germany.
"Further studies should focus on the surveillance of mcr-5 in colistin-resistant Gram-negative pathogens derived from animals, humans and the environment," the authors write.
Apr 11 J Antimicrob Chemother study
Study finds beta-lactamase inhibitor restores susceptibility to carbapenem
In another study today in the Journal of Antimicrobial Chemotherapy, an international team of researchers report that the novel beta-lactamase inhibitor relebactam restored susceptibility to imipenem in gram-negative pathogens.
For the study, which was funded by Merck & Co., the researchers tested the in vitro activity of imipenem and imipenem/relebactam against isolates of Gram-negative ESKAPE pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) submitted by hospital laboratories in 17 European countries. The isolates were from intra-abdominal infections, urinary tract infections, and lower respiratory tract infections. Relebactam was tested at a fixed concentration of 4 mg/L in combination with doubling dilutions of imipenem.
Rates of susceptibility to imipenem and imipenem/relebactam among isolates of P aeruginosa, K pneumoniae, and Enterobacter spp. were 72/94.7%, 88.7/94.8%, and 95.6/96.8%, respectively. In addition, relebactam restored in vitro imipenem susceptibility in 81.1%, 54.2%, and 26.5% of imipenem-non-susceptible isolates of P aeruginosa, K pneumoniae, and Enterobacter spp. Against A baumannii, however, relebactam did not increase the number of isolates susceptible to imipenem. Most imipenem/relebactam-non-susceptible isolates harbored metallo-beta-lactamase, OXA-48, or GES carbapenemase genes.
Imipenem/relebactam has successfully completed two phase 2 clinical trials for treating complicated intra-abdominal infections and complicated urinary tract infections, and is currently in phase 3 development.
"Further development of imipenem/relebactam appears worthwhile as it may provide a valuable therapeutic option for treating patients with infections caused by carbapenem-non-susceptible isolates of Gram-negative bacilli, including ESKAPE pathogens," the authors write.
Apr 11 J Antimicrob Chemother study
Troubling rate of infections, antimicrobial use found in Scottish nursing homes
A national point prevalence survey (PPS) indicates that healthcare associated infections (HCAIs) affect three residents in every long-term care facility (LTCF) in Scotland, Health Protection Scotland reported yesterday.
The PPS, which was conducted in October 2017 and included data from 2,147 residents in 52 LTCFs in Scotland, found that the prevalence of HCAIs was 5.9%. Respiratory tract infections (38.1%), urinary tract infections (31%), and skin and soft-tissue infections (23%) were the most commonly reported HCAIs. The HCAI prevalence was more than twice the rate found in a PPS conducted by the European Centre for Disease Prevention and Control in 2010, though the results aren't directly comparable due to differences in survey protocol.
The PPS also found that the overall prevalence of systemic antimicrobial prescribing in Scottish LTCF was 6.5%, down slightly from the 2010 PPS (7.3%). The prevalence of antimicrobial prescribing for treatment of infections was 4.5%, and the prevalence of prescribing for prevention of infections was 1.3%. The most commonly prescribed antimicrobials for treatment of infection were amoxicillin, trimethoprim, flucloxacillin, and nitrofurantoin.
Scottish health officials said in a news release that the prevalence of HCAIs and the rate of antimicrobial prescribing at LTCFs, along with the challenges of infection prevention and control in these settings, represent a public health threat with implications for resident safety and antimicrobial resistance.
"Healthcare associated infections remain a public health threat across all care settings," said Health Protection Scotland's Jacqui Reilly, PhD. "Health Protection Scotland will develop national programmes to tackle these new threats and work with colleagues across health and social care settings to preserve antibiotics for future use."
The report concludes that a broader and coordinated public health approach to infection prevention and control and antimicrobial stewardship in LTCFs is needed.
Apr 10 Health Protection Scotland PPS
Apr 10 Health Protection Scotland news release