Aurélie Guillouzouic

Nosocomial outbreak of carbapenem-resistant Enterobacter cloacae highlighting the interspecies transferability of the blaOXA-48 gene in the gut flora

Sir, The emergence and dissemination of carbapenemases (KPC, VIM, IMP, NDM or OXA-48) among Enterobacteriaceae is a serious concern worldwide as it raises the problem of the lack of therapeutic options linked to frequent co-resistance. In November 2010, French guidelines were published to control the spread of carbapenemase-producing Enterobacteriaceae from patients repatriated and travellers hospitalized in French hospitals. However, we report the in vivo interspecies transferability of the OXA-48 carbapenemase by the investigation and management of a nosocomial outbreak in France. In April 2011, an elderly patient (Patient A) was transferred from Agadir (Morocco) to the internal medicine unit at Nantes University Hospital, France, for the treatment of a hip prosthetic joint infection. Upon admission, contact precautions were immediately adopted. A rectal swab inoculated on CHROMagarTM KPC medium (CHROMagar, Paris, France) revealed the gastrointestinal carriage of Enterobacter cloacae and Escherichia coli, both resistant to ertapenem and positive for blaOXA-48 by PCR. Therefore, a weekly colonization surveillance was performed on all patients hospitalized in the unit, and led to the discovery of OXA-48-producing E. cloacae in 3/54 patients (B, C and D) without recent history of travel. Furthermore, rectal swabs performed for Patients A and B found two OXA-48-producing Klebsiella pneumoniae isolates (Figure 1). The time between admission to the unit and the first positive culture varied between 3 and 16 days for the three secondary patients. However, Patient D, with a first negative screening, was transferred to the intensive care unit, and was detected as a carrier 3 days after re-admission to the internal medicine unit. We cannot exclude the possibility that this patient was colonized during the first stay in the internal medicine unit. OXA-48-producing E. cloacae isolates were detected intermittently in this patient (Figure 1). None of the four carriers developed infection. Active surveillance was continued until the last colonized patient was discharged. All isolates were resistant to ertapenem (range of MICs, 2 to ≥32 mg/L) and exhibited intermediate susceptibility or susceptibility to imipenem (range of MICs, 0.38–6 mg/L) and meropenem (range of MICs, 0.25–0.5 mg/L) according to the EUCAST guidelines 2011. Molecular testing showed that all E. cloacae isolates harboured the blaCTX-M-15 ESBL gene, while both E. coli and K. pneumoniae isolates were susceptible to third-generation cephalosporins and did not present any of the additional b-lactamases searched for (blaTEM, blaSHV apart from blaSHV-1, and blaCTX-M). The E. coli and K. pneumoniae isolates did not yield subcultures when plated on a CHROMagarTM ESBL medium (CHROMagar, Paris, France). Although other authors reported poor growth of E. coli strains, and underlined difficulties in differentiating colonies of E. cloacae and K. pneumoniae, in our experience the CHROMagarTM KPC medium was useful. The OXA-48 producing E. coli isolate from Patient A yielded a few small pink colonies, whereas the OXA-48producing K. pneumoniae isolate showed better growth, with large navy blue colonies easily distinguishable from the steel blue colonies of the OXA-48-producing E. cloacae isolate. All E. cloacae isolates showed indistinguishable PFGE patterns. According to PFGE and multilocus sequence typing (MLST; http://www.pasteur.fr/recherche/genopole/PF8/mlst/ Kpneumoniae.html) analyses, K. pneumoniae isolates were not clonally related [one new sequence type (ST) and one ST152]. The E. coli isolate belonged to ST38 (MLST, http://mlst.ucc.ie/ mlst/dbs/Ecoli). The blaOXA-48 gene was transferred by conjugation 4 to a rifampicin-resistant E. coli J53-2 from the E. cloacae, K. pneumoniae and E. coli isolates, while transfer of the blaCTX-M-15 gene from the E. cloacae isolates failed. Extraction of plasmids revealed that E. cloacae isolates carried two plasmids (60 and 165 kb), whereas E. coli, both K. pneumoniae isolates and all blaOXA-48-positive transconjugants carried a single plasmid that co-migrated with the 60 kb plasmid of E. cloacae isolates. The blaOXA-48 gene was part of the plasmid-borne Tn1999.2 transposon, since an insertion sequence IS1999 interrupted by an IS1R was detected by PCR mapping upstream of the blaOXA-48 gene. 2 This is the first report of a patient colonized with three enterobacterial isolates (E. cloacae, E. coli and K. pneumoniae) harbouring the blaOXA-48 gene. The emergence of this gene has been linked to the spread of a peculiar Tn1999-type transposon, but also to the dissemination of specific clones. Poirel et al. indicated that the same strain of OXA-48-producing E. coli, belonging to ST38, had been imported from Egypt and Turkey into France. In our study, Patient A carried an ST38-type E. coli, but the strain did not display an ESBL phenotype, as previously described. The discovery of the OXA-48 carbapenemase in several enterobacteria of the index case’s gastrointestinal flora rather suggested the possibility of an in vivo transfer of the OXA-48-encoding plasmid. This was confirmed by the isolation of another OXA-48-producing K. pneumoniae isolate in Patient B. In the gut, selection of resistant strains has been associated with a biological fitness cost and often reflects the impact of antimicrobial selection pressure. Previous exposure to fluoroquinolones or antipseudomonal penicillins has been described as a risk factor for acquisition of Research letters

MLST typing of Escherichia coli isolates overproducing AmpC β-lactamase

Escherichia coli is the major commensal aerobic bacterium of the digestive tract of humans and animals, but is also the most frequent human bacterial pathogen. As a consequence, resistance mechanisms carried by this species are of particular concern. One of these mechanisms is the overproduction of the chromosomal AmpC β-lactamase, leading to increased MICs of most β-lactams including third-generation cephalosporins. AmpC overproduction is caused by various mutations in the ampC promoter (–42, –32 and –11) increasing homology with the consensus promoter for RNA polymerase,

Outbreak caused by Proteus mirabilis isolates producing weakly expressed TEM-derived extended-spectrum β-lactamase in spinal cord injury patients with recurrent bacteriuria.

Abstract We performed a retrospective extended-spectrum β-lactamase (ESBL) molecular characterization of Proteus mirabilis isolates recovered from urine of spinal cord injury patients. A incorrectly detected TEM-24-producing clone and a new weakly expressed TEM-derived ESBL were discovered. In such patients, ESBL detection in daily practice should be improved by systematic use of a synergy test in strains of P. mirabilis resistant to penicillins.

Draft Genome Sequences of Four Propionibacterium acnes Strains Isolated from Implant-Related Infections

ABSTRACT Propionibacterium acnes was previously described as a potential implant-related pathogen. Here, we report the draft genome sequence of four P. acnes strains, isolated from spine material, hip arthroplasty, and knee arthroplasty infections in France belonging to different sequence types (ST18, ST27, and ST36).

Draft Genome Sequence of an Erythromycin-Resistant Propionibacterium acnes Isolate Recovered from Folliculitis of the Scalp

ABSTRACT Propionibacterium acnes is now well-known and recognized for its implication in the pathogenesis of acne vulgaris. Here, we report the draft genome sequence of an erythromycin-resistant P. acnes strain isolated from a case of folliculitis of the scalp belonging to phylotype IA1 and sequence type 18 (ST18).

Genotypic and phenotypic characterization of Staphylococcus epidermidis causing chronic relapsing prosthetic joint infections

Abstract Twenty-one isolates of Staphylococcus epidermidis from 9 patients with persistent prosthetic joint infections were analysed by pulsed-field gel electrophoresis and antibiotic susceptibility assays. In 7 of these cases, the S. epidermidis isolate was different from that of the initial episode. In 1 further case, the superinfection was polyclonal. Recurrence, i.e., renewed isolation of a clone identical to that of an initial episode, occurred in 3 cases, 1 of which was in the absence of superinfection. A high degree of antibiotic resistance was demonstrated, including methicillin in 17 of 21 strains. In conclusion, a frequent occurrence of superinfection and a high degree of resistance make management of these infections complex.

Two family members with skin infection due to Dermatophilus congolensis : a case report and literature review

In August 2015, a 44-year-old woman and her 17-year-old daughter consulted the Dermatology department, Nantes University Hospital, France, with skin lesions on both legs with no other clinical symptoms (figure 1A). One month before disease onset, the patients had spent 15 days in Thailand. During the trip, they had swam in rivers and lakes and had suffered insect bites. Moreover, they had been in contact with animals, namely during an elephant ride. They did not report any other contact with livestock [...]

Failure of combination therapy for Staphylococcus aureus bone infection: a case of in vivo selection with resistance to rifampicin and fusidic acid

Abstract Staphylococcus aureus is one of the main etiologies of bone and device-related infections. Treatment of these orthopedic infections combines mostly rifampicin with other antibiotics. The recurrence or failure rate after fusidic acid/rifampicin treatment remains low (<10%). We discuss here a case of antibiotic treatment failure for Staphylococcus aureus bone infection with in vivo selection of rifampicin and fusidic acid resistance. We also report a new mutation in fusA gene involved in fusidic acid resistance.