ABSTRACT
INTRODUCTION: The objective of this study was to evaluate the management of orthopaedic device-related infections (ODRIs) due to Enterococcus spp. MATERIALS AND METHODS: We performed a retrospective cohort study in a French tertiary university hospital. Patients with prosthetic joint- or osteosynthesis-associated infections caused by enterococci from 2013 to 2020 were included. Patients who died within 5 days after surgery; who were in palliative care; or who had osteosynthesis of the hand, foot or vertebra were excluded. RESULTS: Thirty-six patients were included, with 24 in the arthroplasty group and 12 in the osteosynthesis material group. Most infections were polymicrobial (63.9%, n = 23). Debridement, antibiotics and implant retention (DAIR) was performed in 30.6% (n = 11), withdrawal of material in 16.7% (n = 6), one-stage exchange in 30.6% (n = 11) and two-stage exchange in 22.2% of cases (n = 8). The antibiotic regimen was amoxicillin in 41.6% (n = 15), rifampicin in 27.8% (n = 10), linezolid in 25% (n = 9) and/or fluoroquinolones in 30.6% (n = 11). Clinical success at 1 year was 67% (18/27). The only variable statistically associated with a decreased risk of clinical failure was a duration of antibiotic therapy of 12 weeks (p = 0.04). Patients with a lower body mass index and age tended to decrease the risk of clinical failure (p = 0.05 and 0.06 respectively). CONCLUSIONS: The management of enterococcal ODRIs is complex, and ODRI patients are at high risk for relapse. In our small study, a better outcome was not demonstrated for patients with combination therapy and rifampicin use. Further studies are needed to improve the medico-surgical strategy for treating these infections.
Subject(s)
Orthopedics , Prosthesis-Related Infections , Humans , Enterococcus , Rifampin/therapeutic use , Retrospective Studies , Treatment Outcome , Anti-Bacterial Agents/therapeutic use , Prosthesis-Related Infections/drug therapy , Prosthesis-Related Infections/surgery , DebridementABSTRACT
OBJECTIVES: Ceftolozane-tazobactam (C/T) proved its efficacy for the treatment of infections caused by non-carbapenemase producing Pseudomonas aeruginosa and Enterobacterales. Here, we aimed to provide susceptibility data on a large series of Enterobacterales since the revision of EUCAST categorization breakpoints in 2020. METHODS: First, C/T susceptibility was determined on characterized Enterobacterales resistant to third generation cephalosporins (3GCs) (extended spectrum ß-lactamase [ESBL] production or different levels of AmpC overexpression) (n = 213) and carbapenem-resistant Enterobacterales (CRE) (n = 259), including 170 carbapenemase producers (CPE). Then, 1632 consecutive clinical Enterobacterales responsible for infection were prospectively collected in 23 French hospitals. C/T susceptibility was determined by E-test® (biomérieux) and broth microdilution (BMD) (Sensititre™, Thermo Scientific) to perform method comparison. RESULTS: Within the collection isolates, 88% of 3GC resistant strains were susceptible to C/T, with important variation depending on the resistance mechanism: 93% vs. 13% susceptibility for CTX-M and SHV-ESBL producers, respectively. Only 20% of the CRE were susceptible to C/T. Among CPE, 80% of OXA-48-like producers were susceptible to C/T, whereas all metallo-ß-lactamase producers were resistant. The prospective study revealed that 95.6% of clinical isolates were susceptible to C/T. Method comparison performed on these 1632 clinical isolates demonstrated 99% of categorization agreement between MIC to C/T determined by E-test® in comparison with the BMD (reference) and only 74% of essential agreement. CONCLUSION: Overall, C/T showed good activity against wild-type Enterobacterales, AmpC producers, and ESBL-producing Escherichia coli but is less active against ESBL-producing Klebsiella pneumoniae, and CRE. E-test® led to an underestimation of the MICs in comparison to the BMD reference.
Subject(s)
Anti-Bacterial Agents , Pseudomonas Infections , Humans , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Prospective Studies , Enterobacteriaceae/genetics , Pseudomonas aeruginosa , Pseudomonas Infections/drug therapy , Cephalosporins/pharmacology , Cephalosporins/therapeutic use , Tazobactam/pharmacology , Tazobactam/therapeutic use , Escherichia coli , beta-Lactamases/geneticsABSTRACT
OBJECTIVE: Medicinal leech therapy - known as hirudotherapy (HT) - is an empirical medical technique that has become popular again in reconstructive surgery. However, at each step of leech management there are risks for blood contamination of the caregivers and severe infections for patients. This reduces the success of the treatment. The aim of this study was to improve the management of leeches from ordering to disposal to improve patient care. METHODS: First, a review of the literature was performed. Second, we conducted a retrospective study of patients' antibiotic prophylaxis from January 2018 to December 2019. The data we collected were patient characteristics, the specific care unit at the hospital, indication, contra-indication, posology, duration of HT, number of leeches delivered, antibiotic prophylaxis prescribed and microbial organism, if identified. Third, an interdisciplinary meeting was organised to review the entire leech circuit: ordering, maintenance, prescription, dispensing, application and disposal. RESULTS: At the end of the literature review, six articles based on practices implemented in France were selected for inclusion. These articles discussed antibiotic prophylaxis, iron supplementation, and leech storage, application and disposal. On the retrospective study performed, antibiotic prophylaxis for HT was performed for 60% (30/50) of patients, 77% (23/30) of the prescriptions followed the recommendations for antibiotic prophylaxis, and 20 patients did not receive antibiotic prophylaxis. The interdisciplinary meeting made it possible to define a collegially validated protocol, containing a computerised antibiotic prophylaxis prescription, including per os ciprofloxacin antibiotic prophylaxis, intravenous iron supplementation and biological monitoring. A leech application protocol was created, and the method of leech disposal was revised. CONCLUSION: Despite the absence of clear guidelines and heterogeneous practices, this study reveals the importance of a standard procedure including leech management practices before use, antibiotic prophylaxis and application and disposal guides. The interdisciplinary protocol allows improved patient care management and makes leech management safer for caregivers.
Subject(s)
Leeches , Leeching , Animals , Humans , Leeching/adverse effects , Leeching/methods , Retrospective Studies , Patient Care , France/epidemiologyABSTRACT
In the context of increasing antimicrobial resistance in Enterobacterales, the management of these UTIs has become challenging. We retrospectively assess the prevalence of antimicrobial resistance in Enterobacterales isolates recovered from urinary tract samples in France, between 1 September 2017, to 31 August 2018. Twenty-six French clinical laboratories provided the susceptibility of 134,162 Enterobacterales isolates to 17 antimicrobials. The most frequent species were E. coli (72.0%), Klebsiella pneumoniae (9.7%), Proteus mirabilis (5.8%), and Enterobacter cloacae complex (2.9%). The overall rate of ESBL-producing Enterobacterales was 6.7%, and ranged from 1.0% in P. mirabilis to 19.5% in K. pneumoniae, and from 3.1% in outpatients to 13.6% in long-term care facilities. Overall, 4.1%, 9.3% and 10.5% of the isolates were resistant to cefoxitin, temocillin and pivmecillinam. Cotrimoxazole was the less active compound with 23.4% resistance. Conversely, 4.4%, 12.9%, and 14.3% of the strains were resistant to fosfomycin, nitrofurantoin, and ciprofloxacin. However, less than 1% of E. coli was resistant to fosfomycin and nitrofurantoin. We identified several trends in antibiotics resistances among Enterobacterales isolates recovered from the urinary tract samples in France. Carbapenem-sparing drugs, such as temocillin, mecillinam, fosfomycin, cefoxitin, and nitrofurantoin, remained highly active, including towards ESBL-E.
ABSTRACT
Zoonotic species of Capnocytophaga genus belong to the oral microbiota of dogs and cats. They may be responsible for serious human infections, mainly after animal bites, with a high mortality rate. In France, only few cases have been reported and no multicenter study has been conducted. Our aim was to describe the French epidemiology of Capnocytophaga zoonosis. We conducted a multicenter (21 centers) retrospective non-interventional, observational study in France describing the epidemiology of Capnocytophaga zoonosis (C. canimorsus, C. cynodegmi, C. canis) over 10 years with regard to clinical and bacteriological data. From 2009 to 2018, 44 cases of Capnocytophaga zoonotic infections were described (C. canimorsus, n = 41; C. cynodegmi, n = 3). We observed an increase (2.5 times) in the number of cases over the study period (from the first to the last 5 years of the study). The most frequent clinical presentations were sepsis (n = 37), skin and soft tissue infections (n = 12), meningitis (n = 8), osteoarticular infections (n = 6), and endocarditis (n = 2). About one-third of patients with sepsis went into septic shock. Mortality rate was 11%. Mortality and meningitis rates were significantly higher for alcoholic patients (p = 0.044 and p = 0.006, respectively). Other comorbidities included smoking, splenectomy, diabetes mellitus, and immunosuppressive therapy are associated to zoonotic Capnocytophaga infection. Eighty-two percent of cases involved contact with dogs, mostly included bites (63%). Despite all isolates were susceptible to the amoxicillin-clavulanic acid combination, three of them were resistant to amoxicillin.
Subject(s)
Alcoholism , Bites and Stings , Cat Diseases , Dog Diseases , Gram-Negative Bacterial Infections , Animals , Bites and Stings/complications , Bites and Stings/epidemiology , Capnocytophaga , Cat Diseases/microbiology , Cats , Dog Diseases/microbiology , Dogs , Gram-Negative Bacterial Infections/microbiology , Humans , Retrospective Studies , Zoonoses/epidemiology , Zoonoses/microbiologyABSTRACT
Temocillin is used for several years in some European countries but, only since 2015 in France. We assessed the susceptibility of Enterobacterales strains isolated from blood culture 1 year before (2014) and 2 years after (2017) its use in France. 1,387 strains were included by 17 clinical laboratories located throughout France: 363 in 2014 and 1,024 in 2017. The rate of resistance to temocillin was 4.6% and 26.7% in 3rd generation cephalosporin (3GC) susceptible and resistant strains respectively. Cephalosporinase-overproducer (COPE) strains were significantly more resistant to temocillin (37.7%) than ESBL-producer (ESBL-PE) (23.5%) (P < 0.01). The rate of temocillin resistance was correlated to the number of inactive beta-lactams. The rate of resistance to temocillin trend to increase from 13.9% in 2014 to 23.9% in 2017 (P < 0.01). Temocillin remains highly active against Enterobacterales but the trend in resistance should be assessed over time.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Enterobacteriaceae Infections/microbiology , Enterobacteriaceae/drug effects , Penicillins/pharmacology , Dose-Response Relationship, Drug , Enterobacteriaceae Infections/epidemiology , France/epidemiology , Humans , Microbial Sensitivity TestsABSTRACT
Species of the Enterobacter cloacae complex (ECC) represent an increasing cause of hospital-acquired infections and commonly exhibit multiple antibiotic resistances. In order to identify genes that may play a role in its ability to colonize the host, we used the transposon-sequencing (Tn-seq) approach. To this end, a high-density random transposon insertion library was obtained from E. cloacae subsp. cloacae ATCC 13047, which was used to analyze the fitness of ca. 300,000 mutants in Galleria mellonella colonization model. Following massively parallel sequencing, we identified 624 genes that seemed essential for the optimal growth and/or the fitness within the host. Moreover, 63 genes where mutations resulted in positive selection were found, while 576 genes potentially involved in the in vivo fitness were observed. These findings pointed out the role of some transcriptional regulators, type VI secretion system, and surface-associated proteins in the in vivo fitness of E. cloacae ATCC 13047. We then selected eight genes based on their high positive or negative fold changes (FCs) and tested the corresponding deletion mutants for their virulence and ability to cope with stresses. Thereby, we showed that ECL_02247 (encoding the NAD-dependent epimerase/dehydratase) and ECL_04444 (coding for a surface antigen-like protein) may correspond to new virulence factors, and that the regulator ECL_00056 was involved in in vivo fitness. In addition, bacterial cells lacking the flagellum-specific ATP synthase FliI (ECL_03223) and the hypothetical protein ECL_01421 were affected for mobility and resistance to H2O2, respectively. All these results yield valuable information regarding genes important for infection process and stress response of E. cloacae ATCC 13047 and participate to a better understanding of the opportunistic traits in this bacterial pathogen.
ABSTRACT
Enterococcus faecium has become a major opportunistic pathogen with the emergence of vancomycin-resistant enterococci (VRE). As part of the gut microbiota, they have to cope with numerous stresses, including effects of antibiotics and other xenobiotics, especially in patients hospitalized in intensive care units (ICUs) who receive many medications. The aim of this study was to investigate the impact of the most frequently prescribed xenobiotics for ICU patients on fitness, pathogenicity, and antimicrobial resistance of the vanB-positive E. faecium Aus0004 reference strain. Several phenotypic analyses were carried out, and we observed that caspofungin, an antifungal agent belonging to the family of echinocandins, had an important effect on E. faecium growth in vitro We confirmed this effect by electron microscopy and peptidoglycan analysis and showed that, even at a subinhibitory concentration (1/4× MIC, 8 mg/liter), caspofungin had an impact on cell wall organization, especially with respect to the abundance of some muropeptide precursors. By transcriptome sequencing (RNA-seq), it was also shown that around 20% of the transcriptome was altered in the presence of caspofungin, with 321 and 259 significantly upregulated and downregulated genes, respectively. Since the fungal target of caspofungin (i.e., ß-1,3-glucan synthase) was absent in bacteria, the mechanistic pathway of caspofungin activity was investigated. The repression of genes involved in the metabolism of pyruvate seemed to have a drastic impact on bacterial cell viability, while a decrease of glycerol metabolism could explain the conformational modifications of peptidoglycan. This is the first report of caspofungin antibacterial activity against E. faecium, highlighting the potential impact of nonantibiotic xenobiotics against bacterial pathogens.
Subject(s)
Enterococcus faecium , Gram-Positive Bacterial Infections , Vancomycin-Resistant Enterococci , Anti-Bacterial Agents/pharmacology , Antifungal Agents/pharmacology , Caspofungin , Cell Wall , Humans , Microbial Sensitivity Tests , Vancomycin/pharmacologyABSTRACT
Objectives: The aim of the study was to characterize phenotypically and genotypically an uncommon mechanism of resistance to macrolides, lincosamides, and streptogramins (MLS) in a Streptococcus milleri group clinical isolate. Materials and Methods: The isolate UCN96 was recovered from an osteoradionecrosis wound, and was identified using the matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry and the partial sequencing of the sodA gene. Antimicrobial susceptibility testing were carried out by the disk diffusion method and minimal inhibitory concentrations (MICs) were determined by the broth microdilution technique. PCR screening was performed for MLS resistance genes described in Gram-positive bacteria. Specific mutations in the ribosomal proteins L3-, L4-, and L22-encoding genes were also screened and those in domain V of the 23S rRNA gene (rrl). The number of mutated copies of the rrl gene was determined using amplification-refractory mutation system quantitative-polymerase chain reaction (qPCR) analysis. Results: The clinical isolate UCN96 was unambiguously identified as Streptococcus constellatus. It was susceptible to all macrolides and lincosamides (ML) antibiotics except spiramycin (MIC >256 mg/L) while it was also resistant to streptogramins. Screening for all acquired resistance genes was negative and no mutation was found in genes coding for L3, L4, and L22 ribosomal proteins. Of interest, a single mutation, A2062C (according to Escherichia coli numbering), was detected in the domain V of 23S rRNA. Conclusion: Mutations at the position 2062 of 23S rRNA have been detected once in Streptococcus pneumoniae, and not yet in other Streptococcus spp. This mechanism is very likely uncommon in Gram-positive bacteria because different copies of 23S rRNA operons should be mutated for development of such a resistance pattern.
Subject(s)
Anti-Bacterial Agents/pharmacology , Erythromycin/pharmacology , RNA, Ribosomal, 23S/genetics , Spiramycin/pharmacology , Streptococcus milleri Group/drug effects , Streptococcus milleri Group/genetics , Bacterial Proteins/genetics , Drug Resistance, Bacterial/genetics , Genotype , Humans , Lincosamides/pharmacology , Macrolides/pharmacology , Microbial Sensitivity Tests , Phenotype , Real-Time Polymerase Chain Reaction , Streptococcus constellatus/drug effects , Streptococcus constellatus/genetics , Streptogramins/pharmacology , Superoxide Dismutase/geneticsABSTRACT
The study evaluated the in vitro activity of ceftolozane-tazobactam (C/T) against 94 unique clinical isolates of Enterobacter cloacae complex (ECC). No difference was observed according to the ECC cluster. The in vitro activity greatly varied depending on the ß-lactamase-producing profile: 100%, 67%, and 19% of wild-type, extended-spectrum ß-lactamase (ESBL)-producing, and AmpC-overproducing strains, respectively, were susceptible to C/T. The use of C/T could be of interest for the treatment of some infections caused by ESBL-producing AmpC-nonoverexpressing ECC isolates.
Subject(s)
Anti-Bacterial Agents/pharmacology , Cephalosporins/pharmacology , Enterobacter cloacae/drug effects , Enterobacteriaceae Infections/drug therapy , Tazobactam/pharmacology , beta-Lactamase Inhibitors/pharmacology , Bacterial Proteins/genetics , Humans , Microbial Sensitivity Tests/methods , Phenotype , beta-Lactamases/geneticsABSTRACT
OBJECTIVES: Ceftaroline and ceftobiprole are new parenteral cephalosporins with potent activity against methicillin-resistant (MR) staphylococci, which are the leading cause of prosthetic joint infections (PJIs). The aim of this study was to determine and compare the in vitro activities of both molecules against staphylococcal isolates recovered from clinically documented PJIs. METHODS: A collection of 200 non-duplicate clinical isolates [100 Staphylococcus aureus and 100 coagulase-negative staphylococci (CoNS), including 19 and 27 MR isolates, respectively] was studied. Minimum inhibitory concentrations (MICs) of oxacillin, ceftaroline, ceftobiprole, vancomycin, teicoplanin, clindamycin, levofloxacin, linezolid and daptomycin were determined by the broth microdilution method. Bactericidal activity (at 4× MIC) of ceftaroline, ceftobiprole, vancomycin, teicoplanin, linezolid and daptomycin was assessed by time-kill assay. RESULTS: Among the S. aureus isolates, 100% were susceptible to ceftaroline (MIC50/90, 0.25/0.5µg/mL) and 98% were susceptible to ceftobiprole (MIC50/90, 0.5/1µg/mL), regardless of their methicillin resistance. The two ceftobiprole-non-susceptible strains (including one MRSA) showed MICs at 4mg/L. Against CoNS isolates, ceftaroline and ceftobiprole exhibited in vitro potency with MIC50/90 values at 0.06/0.25µg/mL and 0.25/1µg/mL, respectively. At 4× MIC, ceftaroline and ceftobiprole showed rapid and marked bactericidal activity against both S. aureus and CoNS (after 24/12h and 12/6h of incubation, respectively), whilst none of the other molecules tested had a bactericidal effect by 24h. CONCLUSIONS: This study showed that ceftaroline and ceftobiprole have excellent in vitro activity against clinical isolates of staphylococci involved in PJIs. These molecules may therefore represent promising alternatives for the treatment of such infections.
Subject(s)
Anti-Bacterial Agents/pharmacology , Cephalosporins/pharmacology , Joint Diseases/microbiology , Methicillin-Resistant Staphylococcus aureus/drug effects , Prosthesis-Related Infections/microbiology , Staphylococcus/drug effects , Daptomycin/pharmacology , Humans , Methicillin-Resistant Staphylococcus aureus/isolation & purification , Microbial Sensitivity Tests , Staphylococcal Infections/microbiology , Staphylococcus aureus/drug effects , Vancomycin/pharmacology , CeftarolineABSTRACT
Objectives: To characterize, phenotypically and genotypically, the first Enterococcus faecium clinical isolate harbouring a vanG operon. Methods: The antibiotic resistance profile of E. faecium 16-346 was determined and its whole genome sequenced using PacBio technology. Attempts to transfer vancomycin resistance by filter mating were performed and the inducibility of expression of the vanG operon was studied by reverse-transcription quantitative PCR (RT-qPCR) in the presence or absence of subinhibitory concentrations of vancomycin. Results: E. faecium 16-346 was resistant to rifampicin (MIC >4 mg/L), erythromycin (MIC >4 mg/L), tetracycline (MIC >16 mg/L) and vancomycin (MIC 8 mg/L), but susceptible to teicoplanin (MIC 0.5 mg/L). The strain harboured the vanG operon in its chromosome, integrated in a 45.5 kb putative mobile genetic element, similar to that of Enterococcus faecalis BM4518. We were unable to transfer vancomycin resistance from E. faecium 16-346 to E. faecium BM4107 and E. faecalis JH2-2. Lastly, transcription of the vanG gene was inducible by vancomycin. Conclusions: This is, to the best of our knowledge, the first report of a VanG-type vancomycin-resistant strain of E. faecium. Despite the alarm pulled because of the therapeutic problems caused by VRE, our work shows that new resistant loci can still be found in E. faecium.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Proteins/genetics , Drug Resistance, Microbial/genetics , Enterococcus faecium/drug effects , Enterococcus faecium/genetics , Gram-Positive Bacterial Infections/microbiology , Vancomycin Resistance , Vancomycin/pharmacology , Adult , Enterococcus faecium/isolation & purification , Female , Gene Expression Profiling , Gene Expression Regulation, Bacterial , Gene Transfer Techniques , Gene Transfer, Horizontal , Genotype , Humans , Interspersed Repetitive Sequences , Microbial Sensitivity Tests , Operon , Phenotype , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Teicoplanin/pharmacology , Whole Genome SequencingABSTRACT
The efficacy of the anti-cancer immunomodulatory agent cyclophosphamide (CTX) relies on intestinal bacteria. How and which relevant bacterial species are involved in tumor immunosurveillance, and their mechanism of action are unclear. Here, we identified two bacterial species, Enterococcus hirae and Barnesiella intestinihominis that are involved during CTX therapy. Whereas E. hirae translocated from the small intestine to secondary lymphoid organs and increased the intratumoral CD8/Treg ratio, B. intestinihominis accumulated in the colon and promoted the infiltration of IFN-γ-producing γδT cells in cancer lesions. The immune sensor, NOD2, limited CTX-induced cancer immunosurveillance and the bioactivity of these microbes. Finally, E. hirae and B. intestinihominis specific-memory Th1 cell immune responses selectively predicted longer progression-free survival in advanced lung and ovarian cancer patients treated with chemo-immunotherapy. Altogether, E. hirae and B. intestinihominis represent valuable "oncomicrobiotics" ameliorating the efficacy of the most common alkylating immunomodulatory compound.
Subject(s)
Cyclophosphamide/pharmacology , Enterococcus hirae/immunology , Immunologic Factors/immunology , Neoplasms/drug therapy , Neoplasms/immunology , Animals , Colon/immunology , Colon/microbiology , Immunologic Memory/immunology , Immunotherapy/methods , Interferon-gamma/immunology , Intestine, Small/immunology , Intestine, Small/microbiology , Mice , Mice, Inbred C57BL , Monitoring, Immunologic , Nod2 Signaling Adaptor Protein/immunology , Th1 Cells/immunologySubject(s)
Anti-Bacterial Agents/pharmacology , DNA-Directed RNA Polymerases/genetics , Drug Resistance, Bacterial , Listeria monocytogenes/drug effects , Mutation, Missense , Prosthesis-Related Infections/drug therapy , Rifampin/pharmacology , Aged , Amino Acid Sequence , Amino Acid Substitution , Anti-Bacterial Agents/therapeutic use , Arthritis/drug therapy , Arthritis/microbiology , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Humans , Listeria monocytogenes/enzymology , Listeria monocytogenes/genetics , Listeriosis/drug therapy , Point Mutation , Polymerase Chain Reaction , Prosthesis-Related Infections/microbiology , Rifampin/therapeutic use , Sequence Analysis, DNAABSTRACT
OBJECTIVES: Aims of this study were to: (i) evaluate whether the cluster membership could have an impact on hetero-resistance phenotype to colistin in the Enterobacter cloacae complex (ECC); and (ii) determine the genetic mechanism of colistin hetero-resistance in ECC. METHODS: A collection of 124 clinical isolates belonging to 13 clusters were used to analyse the hetero-resistance phenotype (MICs were determined using the broth microdilution method, Etest and population analysis profiling). Different mutants (ΔphoP, ΔphoQ, ΔphoPQ, ΔpmrA, ΔpmrB, ΔpmrAB, ΔarnE, ΔarnF and ΔarnBCADTEF) were constructed and tested for their colistin hetero-resistance phenotype. RESULTS: Based on broth microdilution and Etest results, it was shown that the hetero-resistance to colistin depended on the cluster: strains from clusters I, II, IV, VII, IX, X, XI and XII were usually hetero-resistant, whereas those from clusters III, V, VI, VIII and XIII were categorized as susceptible. However, for some cluster V and VIII strains, a small proportion (<10-7) of cells appeared resistant when tested by population analysis profiling. From a mechanistic point of view, analysis of mutants revealed that the mechanism of hetero-resistance was mainly due to the expression of the arn operon and the phoP/phoQ two-component regulatory system. CONCLUSIONS: Because the colistin hetero-resistance appeared cluster-dependent in the ECC, it should be advocated to determine the cluster of the strain associated with the infection in parallel with the MIC of colistin. The resistance mechanism may not be similar to other Enterobacteriaceae since only the two-component regulatory system PhoP/PhoQ (and not PmrA/PmrB) seemed to play a role in resistance regulation.
Subject(s)
Anti-Bacterial Agents/pharmacology , Colistin/pharmacology , Drug Resistance, Bacterial , Enterobacter cloacae/drug effects , Enterobacter cloacae/genetics , Enterobacter cloacae/classification , Enterobacter cloacae/isolation & purification , Enterobacteriaceae Infections/microbiology , Gene Deletion , Genes, Bacterial , Genotype , Humans , Microbial Sensitivity TestsABSTRACT
OBJECTIVES: The aim of the study was to identify the determinant responsible for erythromycin resistance in Helcococcus kunzii clinical isolate UCN99 and to characterize the genetic support and environment of this novel gene. METHODS: MICs were determined using the broth microdilution method according to EUCAST guidelines. The entire genome sequence of H. kunzii UCN99 was determined using a 454/Roche GS Junior sequencer. The fragment encompassing the new resistance gene and its own promoter was cloned into the pAT29 shuttle vector and the recombinant plasmid pAT29Ωerm(47) was expressed in both Staphylococcus aureus and Streptococcus agalactiae. The transcription start site (TSS) was experimentally determined by 5' RACE-PCR. RESULTS: UCN99 exhibited a constitutive macrolide/lincosamide/streptogramin B (MLSB) resistance phenotype, suggesting the presence of an Erm protein. WGS allowed the identification of a novel gene, named erm(47), encoding a protein sharing 44%-48% amino acid identity with known Erm methylases. In both S. aureus and S. agalactiae, the introduction of pAT29Ωerm(47) conferred a significant increase (≥16-fold) in MICs of all macrolides and lincosamides tested, as well as a 4-fold increase in MICs of quinupristin (streptogramin B), confirming the MLSB resistance. The TSS identification revealed the presence of a short leader peptide, potentially implicated in a translational attenuation mechanism. It was also demonstrated that erm(47) was harboured by a 81 kb genomic island integrated into a chromosomal gene. CONCLUSIONS: This is the first description of a novel MLSB resistance determinant, named erm(47). The prevalence of this gene among Gram-positive cocci must be further investigated to determine its clinical significance.
Subject(s)
Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Firmicutes/drug effects , Genes, Bacterial , Lincosamides/pharmacology , Macrolides/pharmacology , Streptogramin B/pharmacology , Chromosomes, Bacterial , Cloning, Molecular , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Firmicutes/genetics , Gene Expression , Microbial Sensitivity Tests , Promoter Regions, Genetic , Sequence Analysis, DNA , Staphylococcus aureus/drug effects , Staphylococcus aureus/genetics , Streptococcus agalactiae/drug effects , Streptococcus agalactiae/genetics , Transcription Initiation SiteABSTRACT
Meningitis due to Mycoplasma hominis in adults is rarely described, with only three cases having been reported to date. A case of fatal meningitis in a 39-year-old patient after a neurosurgical procedure for a subarachnoid haemorrhage is reported herein. Identification and treatment were significantly delayed because of the rarity of the aetiology and difficulty identifying this organism with the routinely used conventional methods, such as Gram staining and agar growth on standard agar plates. Clinical procedures and the treatment of 'culture-negative' central nervous system infections is a real challenge for clinical microbiologists and clinicians, and M. hominis has to be considered as a potential, although very uncommon, pathogen.
Subject(s)
Cross Infection/mortality , Meningitis, Bacterial/mortality , Mycoplasma Infections/mortality , Mycoplasma hominis , Adult , Fatal Outcome , Humans , Male , Subarachnoid Hemorrhage/surgeryABSTRACT
In Gram-negative bacteria, the active efflux is an important mechanism of antimicrobial resistance, but little is known about theEnterobacter cloacaecomplex (ECC). It is mediated primarily by pumps belonging to the RND (resistance-nodulation-cell division) family, and only AcrB, part of the AcrAB-TolC tripartite system, was characterized in ECC. However, detailed genome sequence analysis of the strainE. cloacaesubsp.cloacaeATCC 13047 revealed to us that 10 other genes putatively coded for RND-type transporters. We then characterized the role of all of these candidates by construction of corresponding deletion mutants, which were tested for their antimicrobial susceptibility to 36 compounds, their virulence in the invertebrateGalleria mellonellamodel of infection, and their ability to form biofilm. Only the ΔacrBmutant displayed significantly different phenotypes compared to that of the wild-type strain: 4- to 32-fold decrease of MICs of several antibiotics, antiseptics, and dyes, increased production of biofilm, and attenuated virulence inG. mellonella In order to identify specific substrates of each pump, we individually expressed intransall operons containing an RND pump-encoding gene into the ΔacrBhypersusceptible strain. We showed that three other RND-type efflux systems (ECL_00053-00055, ECL_01758-01759, and ECL_02124-02125) were able to partially restore the wild-type phenotype and to superadd to and even enlarge the broad range of antimicrobial resistance. This is the first global study assessing the role of all RND efflux pumps chromosomally encoded by the ECC, which confirms the major role of AcrB in both pathogenicity and resistance and the potential involvement of other RND-type members in acquired resistance.
Subject(s)
Biofilms/drug effects , Drug Resistance, Multiple, Bacterial/genetics , Enterobacter cloacae/genetics , Gene Expression Regulation, Bacterial , Genome, Bacterial , Multidrug Resistance-Associated Proteins/genetics , Animals , Anti-Bacterial Agents/pharmacology , Anti-Infective Agents, Local/pharmacology , Biofilms/growth & development , Chromosome Mapping , Coloring Agents/pharmacology , Enterobacter cloacae/drug effects , Enterobacter cloacae/metabolism , Enterobacter cloacae/pathogenicity , Gene Deletion , Larva/microbiology , Microbial Sensitivity Tests , Moths/microbiology , Multidrug Resistance-Associated Proteins/metabolism , VirulenceABSTRACT
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.