[Methicillin-resistant Staphylococcus aureus: 15 years of molecular epidemiology in Western Switzerland]. / Staphylococcus aureus résistant à la méticilline : 15 ans de surveillance moléculaire en Suisse romande.

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. Since 2012, a marked decrease in the incidence of cases attributable to the biology of the clones and to the control measures taken in the hospitals has been observed. These results highlight the importance of continuous surveillance in order to better assess the burden of this multi-resistant pathogen in our region.

Depuis l'introduction des antibiotiques, des vagues successives de clones de Staphylococcus aureus sont apparues, chacun avec un profil de susceptibilité aux antibiotiques et de virulence caractéristique. Nous rapportons ici les résultats d'une surveillance épidémiologique moléculaire de S. aureus résistant à la méticilline (MRSA) en Suisse romande entre 2006 et 2020 montrant l'émergence et la disparition de clones connus pour leur dissémination internationale, ainsi que l'apparition sporadique d'autres clones internationaux. Depuis 2012, une diminution marquée de l'incidence des cas attribuable à la biologie des clones et aux mesures de contrôle prises dans les hôpitaux est observée. Ces résultats nous montrent l'importance d'une surveillance continue afin de mieux évaluer le fardeau que représente ce germe multirésistant dans notre région.

Recurrent Campylobacter jejuni Infections with In Vivo Selection of Resistance to Macrolides and Carbapenems: Molecular Characterization of Resistance Determinants.

We present two independent cases of recurrent multidrug-resistant Campylobacter jejuni infection in immunocompromised hosts and the clinical challenges encountered due to the development of high-level carbapenem resistance. The mechanisms associated with this unusual resistance for Campylobacters were characterized. Initial macrolide and carbapenem-susceptible strains acquired resistance to erythromycin (MIC > 256mg/L), ertapenem (MIC > 32mg/L), and meropenem (MIC > 32mg/L) during treatment. Carbapenem-resistant isolates developed an in-frame insertion resulting in an extra Asp residue in the major outer membrane protein PorA, within the extracellular loop L3 that connects ß-strands 5 and 6 and forms a constriction zone involved in Ca2+ binding. The isolates presenting the highest MIC to ertapenem exhibited an extra nonsynonymous mutation (G167A|Gly56Asp) at PorA's extracellular loop L1. IMPORTANCE Carbapenem susceptibility patterns suggest drug impermeability, related to either insertion and/or single nucleotide polymorphism (SNP) within porA. Similar molecular events occurring in two independent cases support the association of these mechanisms with carbapenem resistance in Campylobacter spp.

Methicillin-resistant Macrococcus canis in a human wound.

A hemolytic Macrococcus canis strain (LI021) was isolated for the first time from a human skin infection. The complete genome of LI021 consisting of a 2,216,765-bp circular chromosome was obtained by de novo hybrid assembly of Illumina and Oxford Nanopore technology reads. Strain LI021 belonged to the new sequence type ST75 and was resistant to ß-lactam antibiotics due to the presence of a methicillin resistance gene mecB. The mecB gene as well as putative hemolysin genes hlgB and hlgC were located on a novel composite pseudo (Ψ) SCCmec island. These findings show that a methicillin-resistant M. canis may be associated with human infection and indicate that this bacterium should be considered by human diagnostic laboratories.

A new sexually transmitted infection (STI) in Geneva? Ciprofloxacin-resistant Neisseria gonorrhoeae, 2002-2005.

PRINCIPLES: Neisseria gonorrhoeae (NG) resistant to ciprofloxacin (CR) was documented for the first time in Geneva in 2002 and increased from 7% that year to 47% in 2005. We describe NG cases during this period and compare characteristics of CR and ciprofloxacin susceptible (CS) cases. METHOD: Geneva microbiological laboratories identified NG cases. Antimicrobial susceptibility testing (AST) was performed on a sample of reported cases. The attending physicians completed questionnaires on demographic and epidemiological characteristics. Risk exposures were assessed by comparing CR and CS cases using logistic regression. RESULTS: 238 NG cases were reported. Of 91 on which AST was performed, 23 (25%) were CR; 91% of these were male vs 87% of CS patients. Men having sex with men (MSM) represented 38% of CR cases compared with 31% of CS cases (p>0.05). Among CR cases 65% were Swiss compared with 56% of CS cases. Median age was 35 years for both. Casual sexual contacts were reported for 88% of CR cases and 72% of CS cases (p>0.05). The difference between CR and CS cases in terms of sexual activity outside Switzerland (50% and 19% respectively) remained significant after adjusting for sexual preference and nationality (OR: 7.0, CI 95: 1.99-24.6). CONCLUSION: Although CR infection was more common among Swiss MSM, only sexual activity outside Switzerland was independently associated with CR. Physicians should request AST before treatment and reconsider first-line use of ciprofloxacin. Surveillance of gonococcal antimicrobial resistance is essential in monitoring epidemiologic trends and updating recommendations on first-line treatment.

In vitro antimicrobial susceptibility of Alloscardovia omnicolens and molecular mechanisms of acquired resistance.

All the 31 isolates of Alloscardovia omnicolens exhibited low MICs for ß-lactams, glycopeptides, linezolid, tetracyclines, and cotrimoxazole. One strain showed MICs ≥256µg/mL for both erythromycin and clindamycin with a single point mutation in 23S rRNA. One strain likely had acquired fluoroquinolone resistance associated with a unique mutation in ParC.

Increased incidence of sexually transmitted infections in Geneva, Switzerland.

BACKGROUND: Focal outbreaks of sexually transmitted infections (STIs) such as syphilis and gonorrhoea have been reported in the large cities of Western Europe over the past few years. The aim of our study was to determine whether a similar trend is observed in Geneva and the situation with regard to HIV infection. METHODS: We review the incidence of syphilis, gonorrhoea, Chlamydia trachomatis and HIV in Geneva from 1999 to 2004. RESULTS: Figures indicate a steady and sustained increase in the incidence of syphilis, gonorrhoea and Chlamydia trachomatis in Geneva since 1999 that is maintained into 2004. As for HIV, the number of positive testings in Switzerland has stabilised and primary infection figures do not indicate an increase in newly acquired infections in Geneva. CONCLUSION: The situation in Geneva is similar to that observed elsewhere in Western Europe and indicates the need of public health interventions.

Pneumonia and new methicillin-resistant Staphylococcus aureus clone.

Necrotizing pneumonia caused by Staphylococcus aureus strains carrying the Panton-Valentin leukocidin gene is a newly described disease entity. We report a new fatal case of necrotizing pneumonia. An S. aureus strain with an agr1 allele and of a new sequence type 377 was recovered, representing a new, emerging, community-acquired methicillin-resistant clone.

Detection of new methicillin-resistant Staphylococcus aureus clones containing the toxic shock syndrome toxin 1 gene responsible for hospital- and community-acquired infections in France.

Methicillin-resistant Staphylococcus aureus (MRSA) clones harboring the toxic shock syndrome toxin 1 (tst) gene have been detected in France and in Switzerland since 2002. During a passive survey conducted between 2002 and 2003, we collected 103 tst-positive S. aureus isolates from 42 towns in France, of which 27 were resistant to methicillin. The tst-positive MRSA belonged to two clones: a major clone comprising 25 isolates of sequence type (ST) 5 and agr group 2 and a minor clone comprising two isolates of ST30 and agr3. The tst-positive MRSA clones were associated with both hospital-acquired (12 cases) and community-acquired (8 cases) infections. The MRSA clones were mainly isolated from children (overall median age, 3 years). They caused a variety of clinical syndromes, including toxic shock syndrome and suppurative infections. Both clones were found to harbor a type IV staphylococcal chromosomal cassette mec (SCCmec) and to have similar antibiotic resistance profiles (usually resistant to oxacillin, kanamycin, and tobramycin and with intermediate resistance to fusidic acid). The origin of these clones is unclear. The tst-positive agr2 MRSA clone has the same sequence type (ST5) of two pandemic nosocomial MRSA clones, namely, the Pediatric clone and the New York/Japan clone. These findings suggest that all these clones are phylogenetically related. The pulsotype of the tst-positive MRSA clones differed from that of methicillin-sensitive S. aureus (MSSA) clones by a single band involving the SCCmec element. These findings suggest that the tst-positive MRSA clones may have emerged from their respective MSSA counterparts.

Community-acquired methicillin-resistant Staphylococcus aureus isolated in Switzerland contains the Panton-Valentine leukocidin or exfoliative toxin genes.

Among 10 strains of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) isolated in 2002 from patients with skin infections, seven harbored the Panton-Valentine leukocidin gene, two harbored the exfoliative toxin A gene, and one harbored neither of these genes. CA-MRSA isolates producing a variety of exotoxins are currently spreading in the Swiss community.

Postneurosurgical meningitis due to Proteus penneri with selection of a ceftriaxone-resistant isolate: analysis of chromosomal class A beta-lactamase HugA and its LysR-type regulatory protein HugR.

We report on a case of a postneurosurgical meningitis due to ceftriaxone-susceptible Proteus penneri, with selection of a ceftriaxone-resistant isolate following treatment with ceftriaxone. The isolates presented identical patterns by pulsed-field gel electrophoresis and produced a single beta-lactamase named HugA with an isoelectric point of 6.7. The ceftriaxone-resistant isolate hyperproduced the beta-lactamase (increase in the level of production, about 90-fold). The sequences of the hugA beta-lactamase gene and its regulator, hugR, were identical in both P. penneri strains and had 85.96% homology with those of Proteus vulgaris. The HugA beta-lactamase belongs to molecular class A, and the transcriptional regulator HugR belongs to the LysR family.

Community-acquired methicillin-resistant Staphylococcus aureus carrying Panton-Valentine leukocidin genes: worldwide emergence.

Infections caused by community-acquired (CA)-methicillin--resistant Staphylococcus aureus (MRSA) have been reported worldwide. We assessed whether any common genetic markers existed among 117 CA-MRSA isolates from the United States, France, Switzerland, Australia, New Zealand, and Western Samoa by performing polymerase chain reaction for 24 virulence factors and the methicillin-resistance determinant. The genetic background of the strain was analyzed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST). The CA-MRSA strains shared a type IV SCCmec cassette and the Panton-Valentine leukocidin locus, whereas the distribution of the other toxin genes was quite specific to the strains from each continent. PFGE and MLST analysis indicated distinct genetic backgrounds associated with each geographic origin, although predominantly restricted to the agr3 background. Within each continent, the genetic background of CA-MRSA strains did not correspond to that of the hospital-acquired MRSA.