Showing papers on "Dalfopristin published in 2011"

Antimicrobial Susceptibility of Staphylococcus aureus and Characterization of Methicillin-Resistant Staphylococcus aureus Isolated from Bovine Mastitis in Korea

Abstract: A total of 402 Staphylococcus aureus isolates from bovine mastitis milk collected during 2003-2009 in Korea were tested for susceptibility to 20 antimicrobial agents. All S. aureus isolates were susceptible to 11 of 20 antimicrobials tested; no resistance was observed against pirlimycin, telithromycin, novobiocin, penicillin/novobiocin, quinupristin/dalfopristin, clindamycin, rifampin, ciprofloxacin, trimethprim/sulfamethoxazol, vancomycin, and linezolid. Over 66% of the S. aureus isolates were resistant to penicillin. Resistance was also seen for gentamicin (11.9%), erythromycin (7.7%), methicillin (oxacillin and cefoxitin, 6.2%), and tetracycline (4.2%). No noticeable change was observed in penicillin, gentamicin, and erythromycin resistance over the 7-year period. Tetracycline resistance appeared to decrease consistently, whereas methicillin resistance was observed from 2005. About 2.7% (11/402) were resistant to three or more antimicrobials. Genotyping of the 17 methicillin-resistant S. aureus (MRSA) isolated from each cow revealed two staphylococcal cassette chromosome mec (SCCmec) types (IV and IVa), three spa types (t286, t324, and untypable), and two sequence types (ST1 and ST72). Eleven of 17 (64.7%) MRSA strains belonged to SCCmec IVa-t324-ST72. The rest of strains belonged to SCCmec IVa-t286-ST1 (n = 3) and SCCmec IV-untypable-ST72 (n = 3). None of the MRSA carried the Panton-Valentine leukocidin gene. These characteristics are the same as those found in community-acquired (CA) MRSA strains prevalent in humans in Korea. Three pulsed-field gel electrophoresis types (A-C) were observed among the 17 MRSA strains examined, and 14 strains belonged to the same pulsed-field gel electrophoresis pattern regardless of their geographical origin and year of isolation. The results of this study provide evidence of CA-MRSA infection in dairy cattle for the first time in Korea.

Dogs Leaving the ICU Carry a Very Large Multi-Drug Resistant Enterococcal Population with Capacity for Biofilm Formation and Horizontal Gene Transfer

Abstract: The enterococcal community from feces of seven dogs treated with antibiotics for 2–9 days in the veterinary intensive care unit (ICU) was characterized Both, culture-based approach and culture-independent 16S rDNA amplicon 454 pyrosequencing, revealed an abnormally large enterococcal community: 14±08×108 CFU gram−1 of feces and 489±115% of the total 16,228 sequences, respectively The diversity of the overall microbial community was very low which likely reflects a high selective antibiotic pressure The enterococcal diversity based on 210 isolates was also low as represented by Enterococcus faecium (546%) and Enterococcus faecalis (454%) E faecium was frequently resistant to enrofloxacin (973%), ampicillin (965%), tetracycline (841%), doxycycline (602%), erythromycin (531%), gentamicin (487%), streptomycin (425%), and nitrofurantoin (265%) In E faecalis, resistance was common to tetracycline (596%), erythromycin (564%), doxycycline (532%), and enrofloxacin (319%) No resistance was detected to vancomycin, tigecycline, linezolid, and quinupristin/dalfopristin in either species Many isolates carried virulence traits including gelatinase, aggregation substance, cytolysin, and enterococcal surface protein All E faecalis strains were biofilm formers in vitro and this phenotype correlated with the presence of gelE and/or esp In vitro intra-species conjugation assays demonstrated that E faecium were capable of transferring tetracycline, doxycycline, streptomycin, gentamicin, and erythromycin resistance traits to human clinical strains Multi-locus variable number tandem repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE) of E faecium strains showed very low genotypic diversity Interestingly, three E faecium clones were shared among four dogs suggesting their nosocomial origin Furthermore, multi-locus sequence typing (MLST) of nine representative MLVA types revealed that six sequence types (STs) originating from five dogs were identical or closely related to STs of human clinical isolates and isolates from hospital outbreaks It is recommended to restrict close physical contact between pets released from the ICU and their owners to avoid potential health risks

Molecular characterization and antimicrobial susceptibility of nasal Staphylococcus aureus isolates from a Chinese medical college campus.

Abstract: Staphylococcus aureus colonization and infection occur more commonly among persons living or working in crowded conditions, but characterization of S. aureus colonization within medical communities in China is lacking. A total of 144 (15.4%, 144/935) S. aureus isolates, including 28 (3.0%, 28/935) MRSA isolates, were recovered from the nares of 935 healthy human volunteers residing on a Chinese medical college campus. All S. aureus isolates were susceptible to vancomycin, quinupristin/dalfopristin and linezolid but the majority were resistant to penicillin (96.5%), ampicillin/sulbactam (83.3%) and trimethoprim/sulfamethoxazole (93.1%). 82%, (23/28) of the MRSA isolates and 66% (77/116) of the MSSA isolates were resistant to multiple antibiotics, and 3 MRSA isolates were resistant to mupirocin—an agent commonly used for nasal decolonization. 16 different sequence types (STs), as well as SCCmec genes II, III, IVd, and V, were represented among MRSA isolates. We also identified, for the first time, two novel STs (ST1778 and ST1779) and 5 novel spa types for MRSA. MRSA isolates were distributed in different sporadic clones, and ST59-MRSA-VId- t437 was found within 3 MRSA isolates. Moreover, one isolate with multidrug resistance belonging to ST398-MRSA-V- t571 associated with animal infections was identified, and 3 isolates distributed in three different clones harbored PVL genes. Collectively, these data indicate a high prevalence of nasal MRSA carriage and molecular heterogeneity of S. aureus isolates among persons residing on a Chinese medical college campus. Identification of epidemic MRSA clones associated with community infection supports the need for more effective infection control measures to reduce nasal carriage and prevent dissemination of MRSA to hospitalized patients and health care workers in this community.

Cross-Resistance to Lincosamides, Streptogramins A, and Pleuromutilins Due to the lsa(C) Gene in Streptococcus agalactiae UCN70

Abstract: Streptococcus agalactiae UCN70, isolated from a vaginal swab obtained in New Zealand, is resistant to lincosamides and streptogramins A (LSA phenotype) and also to tiamulin (a pleuromutilin). By whole-genome sequencing, we identified a 5,224-bp chromosomal extra-element that comprised a 1,479-bp open reading frame coding for an ABC protein (492 amino acids) 45% identical to Lsa(A), a protein related to intrinsic LSA resistance in Enterococcus faecalis. Expression of this novel gene, named lsa(C), in S. agalactiae BM132 after cloning led to an increase in MICs of lincomycin (0.06 to 4 μg/ml), clindamycin (0.03 to 2 μg/ml), dalfopristin (2 to >32 μg/ml), and tiamulin (0.12 to 32 μg/ml), whereas no change in MICs of erythromycin (0.06 μg/ml), azithromycin (0.03 μg/ml), spiramycin (0.25 μg/ml), telithromycin (0.03 μg/ml), and quinupristin (8 μg/ml) was observed. The phenotype was renamed the LSAP phenotype on the basis of cross-resistance to lincosamides, streptogramins A, and pleuromutilins. This gene was also identified in similar genetic environments in 17 other S. agalactiae clinical isolates from New Zealand exhibiting the same LSAP phenotype, whereas it was absent in susceptible S. agalactiae strains. Interestingly, this extra-element was bracketed by a 7-bp duplication of a target site (ATTAGAA), suggesting that this structure was likely a mobile genetic element. In conclusion, we identified a novel gene, lsa(C), responsible for the acquired LSAP resistance phenotype in S. agalactiae. Dissection of the biochemical basis of resistance, as well as demonstration of in vitro mobilization of lsa(C), remains to be performed.

Molecular characterization of vancomycin-resistant enterococci and extended-spectrum β-lactamase-containing Escherichia coli isolates in wild birds from the Azores Archipelago

Abstract: To study the prevalence of vancomycin-resistant enterococci (VRE) and extended-spectrum β-lactamase (ESBL)-containing Escherichia coli isolates, and the mechanisms of resistance implicated, 220 faecal samples from wild birds were collected between 2006 and 2010 in the Azores Archipelago. Samples were spread on Slanetz–Bartley agar plates supplemented with 4 mg/l vancomycin and on Levine agar plates supplemented with 2 mg/l cefotaxime for VRE and ESBL-containing E. coli isolation, respectively. vanA-containing enterococcal isolates (four Enterococcus faecium and two Enterococcus durans) and vanC-1 Enterococcus gallinarum isolates were detected in six and seven faecal samples, respectively. VRE isolates showed ampicillin (n=11), ciprofloxacin (n=9), tetracycline (n=6), erythromycin (n=5), quinupristin/dalfopristin (n=3) and high-level kanamycin resistance (n=1). The tet(L) and/or tet(M) gene was found in all tetracycline-resistant isolates and the erm(B) gene in all erythromycin-resistant isolates. Three va...

Determination of antimicrobial susceptibility patterns and inducible clindamycin resistance in Staphylococcus aureus strains recovered from southeastern Turkey

Abstract: Background In this study, we determined the susceptibility patterns of Staphylococcus aureus strains to various antimicrobials and prevalence of inducible clindamycin resistance (ICR) in these isolates. Methods Two hundred and one S aureus strains, isolated from various clinical samples, were included in the study. Antibiotic susceptibilities were studied by disc diffusion method on the basis of the guidelines by the Clinical and Laboratory Standards Institute. The disc diffusion induction test (D test) was applied to determine ICR resistance among erythromycin-resistant S aureus isolates. Results Of the 201 S aureus strains, 101 (50.2%) were resistant to methicillin. All strains were susceptible to vancomycin, teicoplanin, quinupristin/dalfopristin, and linezolid. It was found that 54 (53.4%) methicillin-resistant S aureus (MRSA) strains were erythromycin resistant, and 40 (39.6%) of them showed constitutive clindamycin resistance. ICR was detected in seven (6.9%) MRSA strains. It was found that 13 (13.0%) methicillin-susceptible S aureus (MSSA) strains were erythromycin resistant. Constitutive clindamycin resistance was seen in one (1.0%) MSSA strain, and ICR was detected in 10 (10.0%) cases. Conclusion There was a high rate of methicillin resistance among S aureus strains in our hospital. However, no statistically significant difference of ICR was observed between MRSA and MSSA strains ( p =0.434) or between inpatients and outpatients ( p =0.804). It was concluded that ICR should be routinely evaluated in each S aureus case to avoid therapy failure among patients.

Susceptibility of Bifidobacteria of Animal Origin to SelectedAntimicrobial Agents

Abstract: Strains of the genus Bifidobacterium are frequently used as probiotics, for which the absence of acquired antimicrobial resistance has become an important safety criterion. This clarifies the need for antibiotic susceptibility data for bifidobacteria. Based on a recently published standard for antimicrobial susceptibility testing of bifidobacteria with broth microdilution method, the range of susceptibility to selected antibiotics in 117 animal bifidobacterial strains was examined. Narrow unimodal MIC distributions either situated at the low-end (chloramphenicol, linezolid, and quinupristin/dalfopristin) or high-end (kanamycin, neomycin) concentration range could be detected. In contrast, the MIC distribution of trimethoprim was multimodal. Data derived from this study can be used as a basis for reviewing or verifying present microbiological breakpoints suggested by regulatory agencies to assess the safety of these micro-organisms intended for the use in probiotics.

Staphylococcus aureus and antibiotic resistance

Abstract: After the report of first case of methicillin-resistant Staphylococcus aureus (MRSA) in 1961, MRSA become a major problem worldwide. Over the last decade MRSA strains have emerged as serious pathogens in nosocomial and community settings. Glycopeptides (vancomycin and teicoplanin) are still the current mainstay of therapy for infections caused by MRSA. In the last decade dramatic changes have occurred in the epidemiology of MRSA infections. The isolates with reduced susceptibility and in vitro resistance to vancomycin have emerged. Recently, therapeutic alternatives such as quinupristin/dalfopristin, linezolid, tigecycline and daptomycin have been introduced into clinical practice for treating MRSA infections. Nevertheless, these drugs are only approved for certain indication and resistance has already been reported. In this review, the new information on novel drugs for treating MRSA infections and the resistance mechanisms of these drugs were discussed.

Antimicrobial susceptibility of canine and human Staphylococcus aureus collected in Saskatoon, Canada.

Abstract: Summary Staphylococcus aureus is one of the most common causes of infection in people and is increasingly recognized in dogs. The increasing prevalence of methicillin resistant S. aureus (MRSA) is complicating the treatment of these infections. Panton Valentine leukocidin (PVL), a toxin involved in the pathogenesis of necrotic syndromes in people may be partially responsible for the rise of MRSA. Canine and human S. aureus from the same geographic area are genetically similar, indicating a common population and likely transmission. The implications of increasing antimicrobial resistance complicated by interspecies transmission, necessitates including both dogs and humans in S. aureus resistance surveillance studies. A collection of 126 S. aureus isolates from people (n = 99) and dogs (n = 27) were included, minimum inhibitor concentrations to a panel of 33 antimicrobials used in human and veterinary medicine were determined. No resistance to vancomycin, linezolid, daptomycin, quinupristin/dalfopristin or nitrofurantoin was found. A wide range of antibiograms were found; including resistance to 0–12 drugs (0–6 drug classes). Outstanding antibiograms included a canine MRSA resistant to rifampin and a human MRSA resistant to chloramphenicol. Inducible clindamycin resistance was found among 78% and 4% of canine and human MRSA and 17% and 25% of canine colonizing and human methicillin susceptible S. aureus (MSSA), respectively. Resistance to mupirocin was only found among human isolates including 20% of MRSA and 4% of MSSA. While no canine isolates were PVL positive, 39% of human MRSA and 2% of MSSA carried the gene. The bidirectional transmission of S. aureus between people and dogs necessitates the inclusion of isolates from both species in future studies.

Quinupristin/dalfopristin in Staphylococcus aureus endophthalmitis: a case report.

Abstract: Introduction: The intravitreal injection of antibiotics remains the mainstay of therapy for postoperative endophthalmitis. Bacterial resistance, however, is still a pitfall in achieving an adequate response to treatment. Quinupristin/dalfopristin might be a feasible therapeutic option in these cases. Case presentation: A 55-year-old Hispanic man had endophthalmitis secondary to Staphylococcus aureus in his right eye and was treated with intravitreal 0.4 mg/0.1 ml quinupristin/dalfopristin injection. Inflammation and pain remission were observed at four days after injection. The final best-corrected visual acuity was 20/40. Conclusion: Although vancomycin remains the first-line intravitreal antibiotic therapy against infectious endophthalmitis caused by Gram-positive bacteria, quinupristin/dalfopristin exhibits similar efficacy and is theoretically more active against vancomycin-resistant strains, with no apparent retinal toxicity.

[Frequency of vancomycin-resistant enterococci isolated from blood cultures from 2008 to 2010].

Abstract: Introduction. Enterococci are important hospital-acquired pathogens. The most commonly isolated species of the genus, Enterococcus faecalis and Enterococcus faecium are the third to fourth-most prevalent nosocomial pathogens worldwide. The aim of this study was to determine the frequency of resistance to vancomycin and other antimicrobial agents of Enterococcus spp strains isolated from blood cultures of hospitalized patients. Material and methods. During the three-year period, from 2008 to 2010, 132 strains of Enterococcus spp isolated from blood cultures of hospitalized patients were tested for their susceptibility to ampicillin, vancomycin, gentamycin (high-level resistance), erythromycin, chloramphenicol, teicoplanin, ciprofloxacin by disc diffusion method according to the Clinical and Laboratory Standards Institute recommendations. Susceptibility of vancomycin resistant E. faecium to the same antibiotics and to linezolid, quinopristin/dalfopristin and tigecyclin was determined using VITEK system. Results and discussion. Resistance to vancomycin was detected in 21 (15.9%) Enterococcus spp strains. The percentage of resistance to other antimicrobial agents varied from 23.1% for chloramphenicol to 81.3% for ciproflxacin. All vancomycin resistant enterococci were identified as E. faecium and belonged to phenotype VanA. The resistance to other antibiotics was very high, except for linezolid and quinopristin/dalfopristin (4.7%). The high-level aminoglycoside resistance was 87.6% for gentamycin and 95.2% for streptomycin. All isolates were resistant to ampicillin, teicoplanin and ciprofloxacin. Conclusion. The detected high frequency of multidrug-resistant isolates among vancomycin resistant enterococci is of great importance and suggests the need for further monitoring of susceptibility in order to take adequate measures to prevent and control spreading of resistant strains.

Analysis of the molecular epidemiology and antibiotic sensitivity of vancomycin-resistant enterococci

Abstract: Vancomycin-resistant Enterococci (VRE) are important nosocomial infection agents which have become widespread in recent years. The legal obligation to establish hospital infection control committees and increase in monitoring studies in Turkey has generalized VRE notifications. The treatment options for VRE-induced infections are limited. This study was conducted to identify the molecular epidemiology of the VRE sources found in the study hospital, and to determine the resistance of these strains to various antibiotics. The study was carried out on strains isolated in the microbiology laboratory of Sahinbey Research and Application Hospital, University of Gaziantep. Strains were identified at species level via conventional methods and a fully automated Vitek 2 (Biomerieux, France) identification system. Vancomycin sensitivity was tested via disc diffusion method and E-test (AB Biodisc) strips. Resistance genes of these strains were analyzed via PCR method using GeneOhm VanR (Becton Dickinson, Canada) moleculer tests. In vitro antibacterial efficiency of linezolid, dalfopristin, gentamicin, streptomycin and imipenem was analyzed via the disc diffusion method. All 81 strains included in the study were identified as Enterococcus faecium. VanA gene-type resistance was recorded in 76 (93.8%); vanB gene-type resistance in 2 (2.5%); and nonA-nonB type resistance in 3 (3.7%) of the study strains. No resistance was detected in any of the linezolid and dalfopristine strains. 75 VRE strains (92.6%) were found to be resistant to gentamicin, 28 strains (34.6%) to streptomycin and 79 strains (97.5%) to imipenem. Linezolid and dalfopristin were found to have complete in vitro efficiency against VRE strains, while these strains were found to be highly resistant to other antibiotics tested in the scope of the study. Since treatment of VRE-induced infections is relatively difficult, it is suggested that careful implementation of preventive measures is of great importance to patients in the fight against this agent.

[Antimicrobial sensivity and ability to slime production of koagulaze-negative staphylococci].

Abstract: The aim of this study was to assess the ability of slime production ofcoagulase-negative staphylococci (CONS) and evaluate the susceptibility of bacteria to antibiotics. Strains were isolated from clinical specimens obtained from hospitalized patients. The most frequently isolated species were S. epidermidis (51%), S. hominis (18%), S. haemolyticus (13%). The result of this study shows that 61% of S.epidermidis produce slime on CRA (Congo red agar), whereas none of the tested S. haemolyticus strains has this ability. All examined strains were susceptible to vancomycin, linezolid and quinupristin/ dalfopristin. The majority of strains were susceptible to minocycline, fusid acid, nitrofurantoin and rifampicin. Sixty six percent of isolates were determined as methicillin-resistant coagulase-negative staphylococci.

Characterization of MRSA from bulk tank milk of dairy herds using a commercial microarray

Abstract: Methicillin resistant Staphylococcus aureus (MRSA) has been identified as an emerging pathogen in livestock animals that is readily transferable to humans in contact with livestock. Moreover, MRSA is a mastitis pathogen in dairy cows that can be isolated from bulk tank milk. It was the objective of this study to characterize MRSA from bulk tank milk with respect to their spa- and SCCmec-type, their phenotypic antimicrobial resistance and resistance resp. virulence associated genes using broth microdilution and a microarray for S. aureus. Bulk tank milk samples (25 ml) were tested for MRSA using a 2 step selective enrichment protocol. Presumptive MRSA were confirmed using a triplex PCR targeted at identification of S. aureus and the mecA gene that encodes resistance to methicillin. A total of 36 isolates derived from monitoring programs and collected within other frameworks in 2009 and 2010 were included in the characterization. All isolates displayed spa-types assigned to the clonal complex CC398. Based on the epidemiological cut-off values for the interpretation of minimum inhibitory concentrations isolates were resistant to tetracycline (100%), clindamycin (58%) erythromycin (52%), quinupristin/dalfopristin (36%) and kanamycin (27%). Isolates did not carry genes associated with typical virulence factors for S. aureus such as the Panton-Valentine Leukocidin. However they did carry hemolysin genes. Results show that livestock associated MRSA of clonal complex CC398 does occur in German dairy herds and that the strains have similar properties as described for strains from pigs.