[Methicillin-resistant : 15 years of molecular epidemiology in Western Switzerland].

Since the introduction of antibiotics, successive waves of Staphylococcus aureus clones occurred, each one having characteristic susceptibility pattern to antibiotics and virulence factors. We report here the results of a molecular epidemiological surveillance of methicillin-resistant S. aureus (MRSA) in French-speaking Switzerland between 2006 and 2020 showing the emergence and disappearance of clones known for their international dissemination, and the sporadic appearance of other international clones.

Efficacy of colistin alone and in various combinations for the treatment of experimental osteomyelitis due to carbapenemase-producing Klebsiella pneumoniae.

Objectives: In a new experimental model of carbapenemase-producing Klebsiella pneumoniae osteomyelitis we evaluated the efficacy of colistin alone and in various combinations and examined the emergence of colistin-resistant strains and cross-resistance to host defence peptides (HDPs).

Methods: KPC-99YC is a clinical strain with intermediate susceptibility to meropenem (MIC = 4 mg/L) and full susceptibility to gentamicin, colistin and tigecycline (MICs = 1 mg/L) and fosfomycin (MIC = 32 mg/L). Time-kill curves were performed at 4× MIC.

Performances of the Rapid Polymyxin and Tests for Colistin Susceptibility Testing.

Owing to the emergence of colistin resistance in nonfermenting Gram negative bacteria, reliable and rapid techniques for testing colistin susceptibility are needed. We evaluated the performances of the Rapid Polymyxin and tests using a collection of and clinical isolates. Colistin susceptibility of and isolates (colistin susceptible and colistin resistant) was tested with the Rapid Polymyxin and tests and compared with the broth microdilution method.

Acquisition of Extended-Spectrum β-Lactamase GES-6 Leading to Resistance to Ceftolozane-Tazobactam Combination in .

A clinical isolate resistant to all β-lactams, including ceftolozane-tazobactam and carbapenems, was recovered. It belonged to sequence type 235 and produced the extended-spectrum β-lactamase (ESBL) GES-6 differing from GES-1 by two amino acid substitutions (E104K and G170S). GES-6 possessed an increased hydrolytic activity toward carbapenems and to ceftolozane and a decreased susceptibility to β-lactamase inhibitors compared to GES-1, except for avibactam.

Evaluation of the Rapid Polymyxin NP test and its industrial version for the detection of polymyxin-resistant Enterobacteriaceae.

The commercial Rapid Polymyxin NP test was evaluated to detect colistin-resistant Enterobacteriaceae. A total of 223 enterobacterial isolates corresponding to 136 resistant (including 38 MCR-like producers), 19 heteroresistant, and 78 colistin-susceptible isolates were tested. The test was performed according to the manufacturer's instruction, and the color of the wells was read after 2 and 3 hours of incubation.