Reto Lienhard

In vitro susceptibility of Actinobaculum schaalii to 12 antimicrobial agents and molecular analysis of fluoroquinolone resistance

OBJECTIVES To assess the in vitro susceptibility of Actinobaculum schaalii to 12 antimicrobial agents as well as to dissect the genetic basis of fluoroquinolone resistance. METHODS Forty-eight human clinical isolates of A. schaalii collected in Switzerland and France were studied. Each isolate was identified by 16S rRNA sequencing. MICs of amoxicillin, ceftriaxone, gentamicin, vancomycin, clindamycin, linezolid, ciprofloxacin, levofloxacin, moxifloxacin, co-trimoxazole, nitrofurantoin and metronidazole were determined using the Etest method. Interpretation of results was made according to EUCAST clinical breakpoints. The quinolone-resistance-determining regions (QRDRs) of gyrA and parC genes were also identified and sequence analysis was performed for all 48 strains. RESULTS All isolates were susceptible to amoxicillin, ceftriaxone, gentamicin, clindamycin (except three), vancomycin, linezolid and nitrofurantoin, whereas 100% and 85% were resistant to ciprofloxacin/metronidazole and co-trimoxazole, respectively. Greater than or equal to 90% of isolates were susceptible to the other tested fluoroquinolones, and only one strain was highly resistant to levofloxacin (MIC ≥32 mg/L) and moxifloxacin (MIC 8 mg/L). All isolates that were susceptible or low-level resistant to levofloxacin/moxifloxacin (n = 47) showed identical GyrA and ParC amino acid QRDR sequences. In contrast, the isolate exhibiting high-level resistance to levofloxacin and moxifloxacin possessed a unique mutation in GyrA, Ala83Val (Escherichia coli numbering), whereas no mutation was present in ParC. CONCLUSIONS When an infection caused by A. schaalii is suspected, there is a risk of clinical failure by treating with ciprofloxacin or co-trimoxazole, and β-lactams should be preferred. In addition, acquired resistance to fluoroquinolones more active against Gram-positive bacteria is possible.

Actinobaculum schaalii: clinical observation of 20 cases

Actinobaculum schaalii is a new species that has so far been isolated from human blood, urine and pus. Its importance has probably been underestimated and other Actinobaculum spp. may also have been underdiagnosed. This retrospective study comprises all known cases of A. schaalii infections identified since 2004 in the canton of Neuchâtel (170,000 inhabitants), Switzerland. Strains were cultivated and isolated in the bacteriology laboratory using its routine procedure. Identification included a Rapid ID 32 A strip (bioMérieux) and 16S rRNA gene sequencing. Twenty-one positive samples were found in 19 patients (11 male, 8 female) of all ages (range 16-91 years): 10 from urine (50%), six from blood (30%), one from both blood and urine (5%), and three from pus (15%). Thirteen out of 17 (76%) cases with either blood or urine specimens had underlying genitourinary tract pathologies. When urine cultures were positive for A. schaalii, leucocytes were found in all samples (10/10, 100%) but all nitrite tests were negative (10/10, 100%). The onset of appropriate treatment was delayed due to the diminished sensitivity of A. schaalii to the antibiotics commonly used for UTIs (i.e. ciprofloxacin and trimethoprim/sulfamethoxazole) and to the delay in microbiological diagnosis. A. schaalii should specifically be searched in all cases of leukocyturia with a negative nitrite test but with Gram-positive rods in the Gram stain, in patients with underlying genitourinary tract pathology, instead of dismissing these findings as clinically irrelevant colonization by coryneform bacteria. This infection may be much more common than previously thought.

Post liposuction infections by rapidly growing mycobacteria

Abstract Rapidly growing mycobacteria (RGM) are recognized agents of surgical site infections. Recently, RGM skin and soft tissue infections have been increasingly reported. As symptoms, clinical signs and disease latency remain non-specific and microbiological detection requires targeted growth media, RGM diagnosis remains challenging for clinicians. Appropriate management is often delayed due to lack of awareness of these infections. RGM infections after plastic surgery have also been described in the setting of interventions performed in developing countries, a growing phenomenon commonly known as medical tourism. We describe a case of Mycobacterium chelonae/abscessus infection following liposuction and liposculpture procedures performed in the Dominican Republic and review the literature on this subject.

Plasmid-mediated carbapenem-hydrolysing β-lactamase KPC-2 in a Klebsiella pneumoniae isolate from Switzerland

Service de Bacteriologie-Virologie, INSERM U914: ‘Emerging Resistance to Antibiotics’, Hopital de Bicetre, Assistance PubliqueHopitaux de Paris, Universite Paris-Sud, 94275 Le Kremlin-Bicetre, France; ADMed Microbiologie, 2300 La Chaux-de-Fonds, Switzerland; Service de Medecine, Hopituax Neuchâtelois de Pourtales, 2000 Neuchâtel, Switzerland *Corresponding author. Tel: +33-145-21-20-19; Fax: +33-145-21-63-40; E-mail: nordmann.patrice@bct.aphp.fr

Erm(X)-mediated resistance to macrolides, lincosamides and streptogramins in Actinobaculum schaalii

OBJECTIVES Actinobaculum schaalii is a Gram-positive bacillus increasingly reported as a causative agent of urinary tract infections as well as invasive infections, mainly in the elderly and patients with underlying urological conditions. Since little is known about the molecular basis of antimicrobial resistance in A. schaalii, the aim of this study was to investigate resistance to macrolides, lincosamides and streptogramins (MLS) in this emerging pathogen. METHODS A total of 32 A. schaalii clinical isolates from France and Switzerland were studied. MICs of erythromycin, spiramycin, lincomycin, clindamycin and quinupristin/dalfopristin were determined by the agar dilution method. Resistance genes erm(A), erm(B), erm(C), erm(F), erm(G), erm(X), msr(A) and mef(A) were screened by PCR. The genetic environment was determined by random cloning and PCR mapping. RESULTS Out of 32 isolates tested, 21 were highly resistant to erythromycin, spiramycin, lincomycin and clindamycin (MICs >256 mg/L), whereas 11 exhibited low MICs (MICs < 0.12 mg/L). On the other hand, quinupristin/dalfopristin remained active against all the isolates. An inducible MLSB resistance phenotype was noted in all cases. The erm(X) gene was detected among all resistant strains, whereas none was detected in susceptible strains. Analysis of genetic support and environment revealed that erm(X) was probably part of the chromosome of A. schaalii. CONCLUSIONS This study is the first molecular characterization of MLS resistance in A. schaalii. In all cases, it was due to the presence of erm(X), a methylase gene previously identified in other clinically relevant Gram-positive bacilli.

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

All the 31 isolates of Alloscardovia omnicolens exhibited low MICs for β-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.

Identification and clinical significance of Helcococcus kunzii in human samples

ABSTRACT From 2008 to 2013, 39 Helcococcus kunzii strains were collected from human clinical specimens (79% from foot ulcers), and 85% of the 39 patients were infected. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry and molecular methods accurately identified all isolates. This large study of clinical observations confirms the potential pathogenic role of H. kunzii.

Prevalence of antibodies to Borrelia burgdorferi sensu stricto in humans from a Cuban village

UNLABELLED Lyme disease has not been officially reported in Cuba. However, clinical cases have been serologically reported. Seroprevalence survey of Borrelia burgdorferi sensu stricto antibodies in humans in the country has not been conducted. OBJECTIVE To estimate the prevalence of borrelial antibodies in inhabitants of a village with historically high level of tick infestation. METHODS Serum specimens from 247 persons randomly selected from the population of the village were examined by IgG Western blot using B31 strain for estimating the prevalence of antibodies profile. RESULTS A seroprevalence value interval (95% CI) of 0.6%-7.2% was estimated for the studied population. The prevalent borrelial protein bands on immunoblots were 41, 72, 90/93, 34, 47, 60, 58, 56, 65/66 and 31 kDa in a decreasing order of significance. CONCLUSION These results support the previous serological findings, suggesting the presence of this borreliosis in Cuba.

Co-production of MCR-1 and extended-spectrum β-lactamase in Escherichia coli recovered from urinary tract infections in Switzerland.

The first patient was an 83-year-old man who presented a urinary tract infection caused by E. coli following the urological surgery in December 2015. The E. coli isolate (CDF6) showed resistance to broad-spectrum cephalosporins, and the patient was therefore treated by ertapenem for ten days. The second patient was a 75-year-old man who was admitted for the treatment of an adenocarcinoma in January 2016, and had a nephrostomy due to a renal failure. He presented a first urinary tract infection caused by a Proteus mirabilis isolate. After treatment by cefuroxime for 14 days, an E. coli isolate showing resistance to broad-spectrum cephalosporins (CDF8) was recovered from urine. None of those patients received prior treatment with polymyxin, nor traveled abroad. Both isolates were tested for colistin resistance with the Rapid Polymyxin NP test (ELITech, Signes, France) and were found positive after 2 h of incubation. Disk diffusion susceptibility testing performed on Muller–Hinton (MH) agar (Bio-Rad, Cressier, Switzerland) showed that both isolates exhibited an ESBL profile. Minimal inhibitory concentrations (MICs) were determined using the broth microdilution method using cation-adjusted MH broth (Bio-Rad) and both isolates showed an MIC of colistin at 8 μg/ml. PCR amplifications followed by sequencing detected the mcr-1 gene in both isolates. In addition, the isolates were positive for the blaCTX-M-1 and blaCTX-M-15 ESBL encoding genes, respectively. Multilocus sequence types were determined by amplification and sequencing of seven housekeeping genes, and sequence types were assigned using the Warwick E. coli MLST database (http://mlst.warwick.ac.uk/mlst/dbs/ Ecoli). Phylogenetic groups were determined by the PCRbased Clermont method consisting in the detection of specific virulence genes. Isolates CDF-6 and CDF-8 belonged to ST446 and ST164, respectively, and to the commensal B1 and C phylogenetic groups, respectively. Conjugation followed by PCR-based replicon typing analyzes and plasmid Sir,

Emergence of an MDR Klebsiella pneumoniae ST231 producing OXA-232 and RmtF in Switzerland

Emerging Antibiotic Resistance Unit, Medical and Molecular Microbiology, National Reference Center for Emerging Antibiotic Resistance (NARA), Fribourg, Switzerland; INSERM European Unit, LEA/IAME Paris, France; Department of Medicine, Faculty of Science, University of Fribourg, Fribourg, Switzerland; ADMED Microbiologie, 2300 La Chaux-de-Fonds, Switzerland; Médecine Interne, Hôpital du Jura Bernois, 2610 St-Imier, Switzerland; Institute of Microbiology, University of Lausanne and University Hospital Center, Lausanne, Switzerland