Presence Of Cfr Gene Research Articles

First Case of Staphylococci Carrying Linezolid Resistance Genes from Laryngological Infections in Poland.

Linezolid is currently used to treat infections caused by multidrug-resistant Gram-positive cocci. Both linezolid-resistant S. aureus (LRSA) and coagulase-negative staphylococci (CoNS) strains have been collected worldwide. Two isolates carrying linezolid resistance genes were recovered from laryngological patients and characterized by determining their antimicrobial resistance patterns and using molecular methods such as spa typing, MLST, SCCmec typing, detection of virulence genes and ica operon expression, and analysis of antimicrobial resistance determinants. Both isolates were multidrug resistant, including resistance to methicillin. The S. aureus strain was identified as ST-398/t4474/SCCmec IVe, harboring adhesin, hemolysin genes, and the ica operon. The S. haemolyticus strain was identified as ST-42/mecA-positive and harbored hemolysin genes. Linezolid resistance in S. aureus strain was associated with the mutations in the ribosomal proteins L3 and L4, and in S. haemolyticus, resistance was associated with the presence of cfr gene. Moreover, S. aureus strain harbored optrA and poxtA genes. We identified the first case of staphylococci carrying linezolid resistance genes from patients with chronic sinusitis in Poland. Since both S. aureus and CoNS are the most common etiological factors in laryngological infections, monitoring of such infections combined with surveillance and infection prevention programs is important to decrease the number of linezolid-resistant staphylococcal strains.

Linezolid-Resistant Staphylococcus haemolyticus: Emergence of G2447U and C2534U Mutations at the Domain V of 23Sr RNA Gene

Background: Linezolid an oxazolidinone drug available in both parenteral and oral formulations has emerged as a novel alternative to vancomycin and other second-generation drugs for the treatment of infections from gram-positive cocci. Clinical isolates of linezolid-resistant staphylococci and enterococci were reported. Since then, linezolid-resistant strains have become an increasing problem worldwide. The most frequently reported mechanisms of linezolid resistance include the mutation in 23S ribosomal nucleic acid and presence of cfr gene. Methicillin-resistant coagulase-negative staphylococci (MR-CoNS) and vancomycin-resistant Enterococcus (VRE) have become a worrisome clinical problem. Objective: Therefore, we aimed to determine the distribution of linezolid-resistant strains in an inpatient setting of a tertiary-care hospital in India and to evaluate the resistance mechanisms among these isolates. In addition, the clonal diversity of the isolates was determined by pulsed-field gel electrophoresis (PFGE). Methods: The distribution, clonal diversity, and resistance mechanism of linezolid resistant-Staphylococcus haemolyticus (LRSH) strains were determined. The isolates were identified by MALDI-TOF. The mechanism of resistance was determined by sequence analysis of the domain V of 23SrRNA and screening for cfr gene. Clonal relatedness was defined by PFGE. Results: In total, 13 LRSH isolates were recovered from pus specimens. The 13 LRSH strains isolated had an linezolid MIC of 256 g/mL. Sequencing results revealed G2576T mutations in 7 (53.8%), G2447U in 4 (30.7%) and C2534U in 1 (7.6%) isolate of S. haemolyticus. One isolate of S. haemolyticus showed 2 simultaneous mutations (G2576T and G2447U) in the domain V region of 23Sr RNA gene. PFGE of the LR-SH isolates revealed the presence of 11 clones. Of the 11 clones, clones I and II had 2 isolates each. Isolates of clone I exhibited a band pattern identical with the previous isolates of LRSH isolated from the orthopedic unit. Similarly, isolates of clone II also shared the same band pattern with the previous LRSH isolates from the dermatology unit of our center. Conclusions: This study highlights the importance of continuous monitoring of vigilance of linezolid resistance in staphylococci. Rationalizing the use of linezolid and implementing methods to control the spread of hospital clones is of paramount importance to prevent further dissemination of these strains.Funding: NoneDisclosures: None

Emergence of linezolid-resistant Staphylococcus epidermidis in the tertiary children\u2019s hospital in Cracow, Poland

Coagulase-negative staphylococci, ubiquitous commensals of human skin, and mucous membranes represent important pathogens for immunocompromised patients and neonates. The increasing antibiotic resistance among Staphylococcus epidermidis is an emerging problem worldwide. In particular, the linezolid-resistant S. epidermidis (LRSE) strains are observed in Europe since 2014. The aim of our study was to genetically characterize 11 LRSE isolates, recovered mostly from blood in the University Children’s Hospital in Krakow, Poland, between 2015 and 2017. For identification of the isolates at the species level, we used 16S rRNA sequencing and RFLP of the saoC gene. Isolates were characterized phenotypically by determining their antimicrobial resistance patterns and using molecular methods such as PFGE, MLST, SCCmec typing, detection of the ica operon, and analysis of antimicrobial resistance determinants. All isolates were multidrug-resistant, including resistance to methicillin, and exhibited so-called PhLOPSA phenotype. In PFGE, all isolates (excluding one from a catheter) represented identical patterns, were identified as ST2, and harbored the ica operon, responsible for biofilm formation. Linezolid resistance was associated with acquisition of A157R mutation in the ribosomal protein L3 and the presence of cfr gene. All isolates revealed new SCCmec cassette element composition. Recently, pediatric patients with serious staphylococcal infections are often treated with linezolid. The increasing linezolid resistance in bacterial strains becomes a real threat for patients, and monitoring such infections combined with surveillance and infection prevention programs is very important to decrease number of linezolid-resistant staphylococcal strains.

First Draft Genome Sequence of Linezolid and Rifampicin Resistant <i>Staphylococcus haemolyticus </i>

Linezolid resistance has increasingly been described in coagulase negative staphylococci (CoNS) in recent years. Here, we describe the molecular mechanism of linezolid resistance in Staphylococcus haemolyticus using whole genome sequencing. Three S. haemolyticus isolates (VB5326, VB19458, and VB840) carried G2576T mutation at the domain V of the 23S rRNA. In addition, VB5326 and VB19458 carried the cfr gene in the chromosome. The presence of cfr gene, in combination with G2576T mutation in 23S rRNA, resulted in a high linezolid Minimum inhibitory concentration (MIC) of > 256 µg/ml. Three mutations, including D471E, I527M, and S532N, in rpoB contributed to an increased rifampicin MIC of 32 µg/ml. Subsequent development of linezolid and rifampicin resistance in S. haemolyticus is worrisome and greatly limits clinical management.

The Multi-Drug Resistance CFR Gene : An Evolving Mechanism for Linezolid Resistance in Staphylococcus Aureus

Background: The emergence of linezolid resistance conveyed by the cfr (chloramphenicol-florfenicol resistance) gene in Staphylococcus aureus possess an utmost importance attributable to its ease of spread. Objectives: This study was undertaken for (1) evaluation of the susceptibility of S. aureus clinical isolates from Mansoura University Hospital (MUH), Mansoura, Egypt to linezolid, (2) detection of the risk factors associated with the emergence of linezolid-resistant S. aureus (LRSA) isolates, and (3) detection of the cfr gene encoding for linezolid resistance. Methodology: During the study period, clinical samples were collected from patients admitted to MUH. Antimicrobial susceptibility was assessed by the Kirby-Bauer's disc diffusion method. The minimum inhibitory concentrations (MICs) of linezolid were determined by agar dilution (AD) method. Polymerase chain reaction (PCR) was used for detection of the cfr gene encoding for linezolid resistance. Results: Out of 197 S. aureus isolates, an overall linezolid resistance of 8.1% was perceived by AD method. Among the risk factors associated with acquisition of LRSA, only hospital stay > 2 weeks retained significance in the logistic regression model (P = 0.002). The cfr gene was detected in 37.5% of LRSA isolates by PCR. Conclusion: The existent study disclosed that the presence of cfr gene is a leading mechanism conferring linezolid resistance in S. aureus. Thereby, prudent consumption of linezolid and ongoing surveillance of cfr-positive strains are crucial to prevent the dissemination of cfr-harboring strains in healthcare-settings.

Emergence and Long-Lasting Persistence of Linezolid-ResistantEnterococcus faecium-ST117 in an Oncohematologic Patient After a Nine-Day Course of Linezolid

We report the emergence and long-lasting persistence of linezolid resistance in an ampicillin-resistant Enterococcus faecium strain in the intestine of a neutropenic oncohematologic patient receiving chemotherapy. The patient was first colonized by an epidemic ampicillin-resistant E. faecium (ARE)-ST117 clustering into lineage 78. This clone exhibited resistance to levofloxacin, erythromycin and high-level resistance to streptomycin and gentamicin. After receiving treatment with several broad spectrum antibiotics for febrile neutropenia, a 9-day course of oral linezolid was administered once the patient developed bacteraemia by the same ARE colonizing clone. Linezolid-resistant ARE was detected 17 days later in the follow-up fecal samples and persisted 41 days after suppression of linezolid therapy. Resistance to linezolid was associated with G2576T transversion in the 23S rRNA and the presence of cfr gene was not detected. The persistence of G2576T-ARE strains, especially in oncohematologic patients with injured intestinal membranes, could increase the risk of bacteraemia.

Staphylococcus coagulasa negativos resistentes al linezolid: características fenotípicas, genotípicas y sensibilidad a combinaciones de antibióticos

ObjectiveWe recovered 22 coagulase-negative staphylococci isolates in our hospital to study their identity, susceptibility, epidemiological profile, linezolid resistance mechanisms, and the possibilities of different antibiotic combinations. MethodsIsolate identification was performed using mass spectrometry (Vitek-MS, bioMérieux). Susceptibility testing was carried out with the Vitek-2 system and the broth microdilution method according to CLSI guidelines. Pulsed-field gel electrophoresis (PFGE) was performed to analyze the genetic relationship between isolates. Linezolid resistance mechanisms were evaluated by PCR/sequencing: presence of cfr gene, point mutations in domain V of 23S ribosomal RNA and additional ribosomal mutations (in the rplC, rplD and rplV genes).The in vitro activity of linezolid was investigated alone and in combination with another three antibiotics acting on different cellular targets, using E-test strips. ResultsTwenty isolates were identified as Staphylococcus epidermidis, and 2 as Staphylococcus hominis. PFGE showed that isolates belonged to diverse clones, 21 of them presented mutations in the domain V region of 23S rRNA and the cfr gene was found in 54.5%.Prior administration of linezolid was documented in most of cases.Linezolid in combination with gentamicin showed a synergistic activity in 45.5% of isolates. ConclusionsStaphylococcus epidermidis was the most prevalent linezolid-resistant coagulase-negative staphylococci. All isolates showed increased MIC values compared to other anti-staphylococcal drugs and several linezolid resistance mechanisms. Our data suggest that linezolid plus gentamicin could be a synergistic combination against linezolid-resistant coagulase-negative staphylococci.