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Objective: To evaluate the effect of meticillin-resistant Staphylococcus aureus(MRSA)on the pyroptosis of bone-marrow derived macrophages(BMDM)and investigate the mechanism of MRSA-induced pyroptosis in macrophages. Methods: The BMDM were triggered by the combination of lipopolysaccharide(LPS, 100 ng/ml)with adenosine-triphosphate(ATP, 3 mmol/L)or nigericin(Ng, 10 mmol/L)or treated with MRSA(multiplicity of infection 200, MOI 200)alone to induce pyroptosis in vitro. The cell morphology examination and lactate dehydrogenase(LDH)assay were applied to evaluate the cytotoxicity. The expression of pro- inflammatory cytokines, the interleukin(IL)- 1β, IL- 6 and tumor-necrosis factor(TNF)-α was detected by ELISA. The cleaved caspase-1 and mature IL-1β in the cells and released into the supernatant were detected by Western blotting. The signal pathway for the induction of pyroptosis by MRSA was investigated via the transfection of lentivirus- mediated short- hairpin RNA(shRNA)into the BMDM. Results: The treatment of BMDM with LPS/ATP, LPS/nigericin or MRSA alone caused cytotoxicity and up-regulated the expression of pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α, as well as the caspase-1 activation and mature Zl-1β (P<0.01). After silencing NLRP3 or NLRC4, the expression of IL-1β induced by MRSA was significantly lessened(P< 0.01). Conclusion: MRSA could induce BMDM pyroptosis probably via activating NLRP3 inflammasome or NLRC4 inflammasome.
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Objective To analyze the drug resistance characteristics of 78 strains of meticillin-resistant Staphylococcus aureus (MRSA)for guiding rational use of antibiotics in clinic.Methods 78 strains of MRSA were collected in our hospital from Septem-ber 2013 to March 2014;their antimicrobial susceptibility test and the drug resistant gene were detected by the MIC method and PCR respectively.Results The resistance of MRSA to erythromycin was more than 90%,which to tetracycline and clindamycin was close to 90%,which to quinolones was more than 70%,which to aminoglycosides was more than 50%,which to trimethoprim and sulphame-thoxazole,nitrofurantoin and rifampicin was lower;no strains were resistant to tigecycline,quinupristin/dalfopristin, vancomycin,linezolid;77 strains of MRSA were positive for mecA gene.Conclusion The drug resistance rate of isolated MRSA in our hospital is roughly the same with that reported,but which still has difference among different departments;clinic should select drugs according to the drug susceptibility test results for preventing aggravation of MRSA drug resistance.
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En la última década han sido cada vez más frecuentes los informes de infecciones causadas porcepas de Staphylococcus aureus resistente a meticilina asociadas a la comunidad (CA-MRSA,por Community-associated methicillin-resistant S. aureus). La colonización juega un papelimportante en la epidemiología de tales infecciones. Sin embargo, los estudios de colonizaciónse han centrado principalmente en el ambiente hospitalario y se han hecho muy pocos en lacomunidad. En este trabajo se investigó la frecuencia de colonización por S. aureus en generaly por MRSA en las manos de individuos de la población general no relacionados con el área dela salud, empleando métodos fenotípicos y moleculares. Se obtuvieron mediante hisopado 800muestras de las manos de otros tantos individuos. Se halló colonización por Staphylococcusaureus en 65 muestras (8,1%) y por MRSA en 5 (0,63%). Las 5 cepas de MRSA presentaban elcasete cromosómico mec (SCCmec) de los tipos IV o V, típicamente relacionados con CA-MRSA.Nuestro trabajo evidenció la colonización de las manos por MRSA en individuos de la comunidad,lo cual constituye un importante factor de riesgo, no solo por su asociación con el desarrolloulterior de infecciones, sino también por el potencial de diseminar este microorganismo a lapoblación general.
Community-associated methicillin-resistant Staphylococcus aureus infections (CA-MRSA) havebeen reported with increasing frequency during the past decade. Colonization plays an importantrole in the epidemiology of such infections. However, colonization studies have focused mostlyon hospital settings and only a few have been carried out in communities. This was a study of thefrequency of hand colonization by S. aureus in generaland by CA-MRSA, by means of phenotypical andmolecular methods, in 800 adults from the communitywho had no relationship with the health area.Staphylococcus aureus colonization was found in 65individuals (8.1%) and MRSA was present in 5 (0.63%).The 5 MRSA strains were found to have mecchromosomic cassettes (SCCmec) of either type IV orV, typical of CA-MRSA. Our study provides evidence ofCA-MRSA colonization in the hands of individuals fromthe community. This constitutes an important riskfactor, not only by its association with subsequentinfections, but also for the risk of dissemination of thismicroorganism to the general population.
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Humans , Staphylococcus aureus/growth & development , Staphylococcus aureus/pathogenicityABSTRACT
OBJECTIVE To investigate the resistance of Staphylococcus aureus,includ MRSA and MSSA,to antimicrobial agents in intensive care unit(ICU),and to provide basis for clinical therapy.METHODS K-B disk diffusion method was used to determine the drug susceptibility of 171 strains of S.aureus,and meticillin-resistant S.aureus(MRSA) was detected by using the disk diffusion method according to NCCLS/CLSI.RESULTS In ICU,S.aureus was isolated mostly from the respiratory tract,urine tract and blood.MRSA made up 57.89%.For MRSA and MSSA,no resistance against vancomycin and norvancomycin was observed.The resistance rates of MRSA to other agents were as follows: chloramphenicol 20.45%,and minocycline 20.45%.While the resistance rates of MSSA to other agents were as follows:cefazolin 6.25%,and amikacin 6.25%,minocycline 9.38%.CONCLUSIONS MRSA shows the multidrug resistance.Pathogenic monitoring,keeping the patients apart,rational utilization of antibiotics,medical facility sterilization strictly and intensive hand hygiene are very important to prevent MRSA infection.
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OBJECTIVE To explore the drug resistance of the infection caused by meticillin-resistant Staphylococcus aureus(MRSA) in ICU and the effect of linezolid in the treatment on MRSA.METHODS The collection of sputum,blood,urine,cerebrospinal fluid,the top and local drainage of central venous needle in 3 years(2006 to 2009) in ICU was carried out,and the bacteriological culture and drug susceptibility testing were executed.Fifteen cases of MRSA infection patients were treated with linezolid.RESULTS There were 72 cases of MRSA infection in 3 years in ICU,most of them were drug-resistant.The sensitivity for MRSA infection was high to 100% by used with vancomycin,teicoplanin and linezolid.The trend of MRSA infection in ICU had increased in the past 3 years.The efficiency and recovery rates of linezolid group(73.3% and 33.3%,respectively) were higher than the vancomycin group(66.7% and 28.6%,respectively)(P
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OBJECTIVE To investigate antimicrobial resistance and molecular epidemiology profiles of meticillin-resistant Staphylococcus aureus(MRSA)sampled from lower respiratory tract.METHODS Totally 107 MRSA strains were isolated from lower respiratory tract specimens at Shanghai Pulmonary Hospital between Dec 2005 and Dec 2006.PVL genes were detected by PCR.The genotypes of SCCmec were identified by multiplex PCR.The antimicrobial resistance of MRSA were tested by Kirby-Bauer agar dilution.We also performed the homology of 32 MRSA strains using pulsed-field gel electrophoresis(PFGE).RESULTS All of the 107 MRSA strains were negative in the PVL locus detection and the most frequent SCCmec types were type Ⅲ(81.3%),the others including type Ⅱ(15.9%),type Ⅳ(2.8%),type Ⅰ and type Ⅴ were not found in this group.Those 3 different types of SCCmec were all resistant to ?-lactam antibiotics,less resistant to rifampin,and susceptible to vancomycin,teicoplanin and daptomycin.The resistant rate of those 3 types were different to the non-?-lactam antimicrobial drugs such as trimethoprim/sulfamethoxazole,clindamycin,erythromycin,gentamicin,levofloxacin,and tetracycline,the resistant rate in the types Ⅱ and Ⅲ was significantly higher than the type Ⅳ.PFGE analyses assorted the 32 MRSA strains into 4 PFGE patterns:pulsotype A(25 strains),including subtypes A1(17strains),A2(1 strain)and A3(7 strains);pulsotype B(5 strains),pulsotype C(1 strain),and pulsotype D(1 strain).CONCLUSIONS This study does not found positive PVL locus in the MRSA strains in our hospital,the most frequent SCCmec types are type Ⅲ and some are type Ⅱ.PFGE presented that there are outbreaks of MRSA in ICU ward and TB ward No 5 at that time and the pandemic strains are subtypes A1 and A3,most of these MRSA strains are multiple resistant,which deserves attention from both the clinical staff and infection-control department of the hospital.
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OBJECTIVE To investigate drug-resistance status of Gram-positive cocci in the local region and offer scientific basis for reasonable usage of antibiotics.METHODS 336 strains of Gram-positive cocci were isolated from all kinds of specimens from Jan 2003 to Dec 2007 in the local hospital.Organisms were cultivated and identified complying with National Operation Procedure of the Clinical Laboratory.Drug sensitivity test was performed with K-B methods.RESULTS Among the 336 strains,Staphylococcus aureus(SAU) ranked the top,accounting for 45.8%;then the coagulase-negative Staphylococcus(CNS) accounting for 23.2%;Enterococcus faecalis ranked the third,accounting for 18.2%;the detection rate of meticillin-resistant Staphylococcus aureus(MRSA) was 31.8%;that of meticillin-resistant coagulase-negative Staphylococcus(MRCNS) was 35.9%.The results of drug sensitivity test showed the Gram-positive cocci were resistant to the many antibiotics in different degrees except for 100% sensitive to vancomycin.CONCLUSIONS Hospital should attach importance to supervise the drug-resistance of Gram-positive cocci and prevent the dissemination and epidemic of drug resistant strains.
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OBJECTIVE To investigate the prevalence of meticillin-resistant Staphylococcus (MRS) isolates in Staphylococcus auricularis and S. hominis and detect their drug resistance. METHODS MRS isolates were detected by cefoxitin disc test and susceptibilities were tested by agar dilution method. RESULTS 94.7% and 91.7% MRS isolates were in S. auricularis and S. hominis. MRS strains were resistant to most of antimicrobial agents. There were no isolates resistant to vancomycin and teicoplanin. CONCLUSIONS MRS isolates are highly prevalent in S. auricularis and S. hominis with resistance to most of antimicrobial agents.
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OBJECTIVE To investigate the antibiotic resistance pattern of MRSA,homology and carriage of Panton-valentine leukocidin(PVL) in 50 meticillin-resistant Staphylococcus aureus isolates to guide the clinical treatment.Results of homology provide the proof for molecular epidemiology.METHODS According to CLSI′s guideline,antimicrobial susceptibility tests were performed with disk diffusion method.PVL gene and mecA gene were detected by PCR.The homology was analyzed by repetitive estra-genic palindromic elements(Rep)-PCR method.RESULTS MecA gene was detected in all 50 MRSA isolates.All isolates MRSA were resistant to oxacillin and cefoxitin.But they were all sensitive to vancomycin and teicoplanin.The rates of sensitivity to clindamycin,ciprofloxacin,piperacillin and sulbactam,SMZ-TMP,gentamicin,cefazolin and erythromycin were 7.5%,1.9%,24.5%,92.5%,20.8%,1.9% and 3.8%,respectively.The resistance rates of MRSA were higher than that of MSSA.Twenty PVL genes were detected from 50 MRSA isolates.CONCLUSIONS The resistance rates of MRSA are higher than MSSA.There is no isolate resistant to vancomycin and teicoplanin.40.0% MRSA carry PVL gene and part isolates have high homology.
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OBJECTIVE To investigate the distribution and characteristics of drug-resistance of Staphylococcus aureus (SAU) causing lower respiratory infection, for rational using of antibiotics in clinical practice. METHODS A retrospective analysis on S. aureus isolates and their drug-resistance characteristics were carried out. These strains were isolated from lower respiratory specimens in clinical laboratory of Renmin Hospital of Wuhan University from Jan 2007 to Dec 2007. RESULTS Among 94 strains, 69 were meticillin-resistant S. aureus(MRSA), accounting for 73.40%. All MRSA strains were resistant to penicillin G, while sensitive to vancomycin and teicoplanin. Resistant rate to chloramphenicol was 7.24 %. The average resistance rate of MRSA to quinolones, macrolides and aminoglycosides were relatively high (56.52-98.55%). And resistant rate of MRSA was higher than the meticillin-sensitive S. aureus (MSSA) in average level. CONCLUSIONS Hospitals at all levels are proposed to strengthen drug resistance supervising so as to prevent the infection breaks.
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OBJECTIVE To investigate the resistance of meticillin-resistant Staphylococcus aureus(MRSA) and the occurrence of gene erm.METHODS ATB Staph and microdilute tests were performed to detect the susceptibility to 15 kinds of antibiotics in 50 strains of the S.aureus(SAU).Gene erm of these strains was detected by polymerase chain reaction(PCR).RESULTS There were no strains resistant to vancomycin,teicoplanin,fusidic acid and quinupristin-dalfopristin in 42 strains of MRSA detected.There were no strains sensitive to penicillin,oxacillin,gentamicin,tetracycline,ciprofloxacin and levofloxacin.Thirty-five strains habored gene erm in 42 strains of MRSA.The positive rate of gene erm was 83.3%.CONCLUSIONS The multiple-resistance of the MRSA is a serious issue.The resistance to erythromycin in MRSA is mediated by gene erm which encodes the methylase and changes the target site of drug action.
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OBJECTIVE To study the drug resistance,drug-resistant genes and disinfectant-resistant genes of clinical MRSA isolates.METHODS The sensitivity to penicillin and other 15 antibacterial agents was detected in 56 strains of MRSA by K-B paper disk diffusion.The mecA gene of the ?-lactamase and disinfectant-resistant genes qac(A/B)were detected by PCR.RESULTS All of the 56 strains of MRSA were sensitive to vancomycin and teicoplanin.Drug resistant rate of sulfamethoxzole/trimethoprim,nitrofurantoin,rifampin,tetracycline,levofloxacin,clindamycin and azithromycin were 17.9%,23.2%,82.1%,87.5%,89.3%,92.9% and 96.4%,respectively.All of the 56 strains were resistant to erythromycin,gentamicin,amikacin,penicillin,ampicillin/sulbactam,cefoxitin and ampicillin.In all 56 strains of MRSA,54(96.4%)MRSA isolates were mecA positive and 31(55.4%)MRSA isolates were qac(A/B)positive.CONCLUSIONS Clinically isolated MRSAs is multi-drug-resistant and the qac(A/B)positive rate is very high.
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OBJECTIVE To investigate and analyze the bacteria on the nurse mask in ICU ward and its air effects disinfection.METHODS Sixty masks were examined for the bacteria numbers,germiculture and drug resistance.The bacteria numbers on the mask were recorded in 2,4,6 and 8 h with or without air disinfection,and the numbers of air bacteria were also estimated before and after air disinfection 2,4,6 and 8 h.The kinds and drug resistance of bacteria in the sputum of patients were recorded during the examining time.RESULTS The meticillin-resistant Staphylococcus(MRS,90.6%) and the Escherichia coli(ECO,9.4%) were the major bacteria on the mask.The numbers of bacteria on the mask at 2,4,6 and 8 h with air disinfection were 1.2?1.5,3.4 ?2.8,4.2?3.4 and 5.3?3.6 CFU/cm2,respectively.The numbers of bacteria on the air before air disinfection were 1264?314 CFU/m3 and after air disinfection 2,4,6 and 8 h were 917?213,790?176,676?179 and 483?167 CFU/m3,respectively.The numbers of bacteria on the mask and on the ward air were decreased obviously after the air disinfection comparing without disinfection.MRS was found in 26.7% patients sputum,and had the same drug-resistance spectrum as the bacteria on the mask.CONCLUSIONS MRS and ECO may be infected through air,and the effective air disinfection could reduce the numbers of bacteria on the air,and decrease the possibility of intercross infection.
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OBJECTIVE To investigate and analyze the reasons of nosocomial infection(NI) in patients in intensive care unit( ICU),to find effective countermeasures for preventing NI and reducing the incidence rate of NI in ICU,and to enhance the management of ICU.METHODS All data of patients who suffered MRSA in ICU from Dec 2005 to Feb 2006,were analyzed by prospective monitoring and retrospective studies.RESULTS The nine patients were with lower respiratory tract.All were infected by the same MRSA.The same MRSA strain was found from hand,mouth and nose among the treating doctor and nurses based on the sample-analysis.CONCLUSIONS The incidence rate of NI in ICU is much higher than that in other departments.Risk factors depend on the severity of underlying diseases,invasive procedure,the quality of disinfection and sterilization,the incorrect use of the antibiotic,and patients′ immunity status especially among elderly.The key way to reduce incidence rate of NI is to take comprehensive measures and strengthen the antibiotic management.
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OBJECTIVE To study the drug resistance,drug-resistant genes and(disinfectant)-resistant genes of(MRS)A.METHODS The drug resistance and mecA gene of the ?-lactamase and aac(6′)/aph(2″),aph(3′)-Ⅲ,ant(4′,4″) genes of aminoglycoside and qac(A/B) disinfectant-resistant genes were(detected) in 47 strains of MRSA.(RESULTS) In all 47 strains of MRSA,46 MRSA isolates were mecA positive,39 MRSA isolates were aac(6′)/aph(2″) positive,30 MRSA isolates were aph(3′)-Ⅲ positive,6 MRSA isolates were ant(4′,4″) positive,and 19 MRSA isolates were qac(A/B) positive.CONCLUSIONS MRSA is multiple-drug resistant.The main resistant mechanisms of MRSA to aminoglycosides and disinfectant are related to the drug-resistant genes of aminoglycoside and disinfectant-resistant genes.Clinic physician must pay attention to the diagnosis and(therapy) of MRSA,and control the hospital infection.
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OBJECTIVE To develop a rapid method for simultaneously identifying Staphylococcus aureus(SA) and its resistance against meticillin. METHODS The target strains authenicated to Staphylococcus by traditional methods(appearance,Gram-stain,catalase) first,then using Slidex~staph.plus to authenticate SA;establishing traditional method or coagulase test and ATB-ID32STAPH system for verification.The penicillin-binding protein 2a(PBP2a) was examined by Slidex MRSA Detection,establishing resistance oxacillin sieving test and mecA gene was examined by PCR for verification. RESULTS The 135 strains were positive and 321 strains were negative for Slidex~staph.plus from 456 strains.The 127 S.aureus strains and eight others were confirmed from 135 positive strains finally,11 SA strains and 310 other strains were confirmed from 321 negative strains,there were 92.0% for sensitivity and 97.5% for specificity in this method.The 52 strains PBP2a positively confirmed to meticillin-resistant S.aureus(MRSA) using Slidex MRSA Detection and 57 MRSA strains were confirmed using resistance oxacillin sieving test or PCR from 138 strains.There were 91.2% for sensitivity and 100% for specifity in this method. CONCLUSIONS The duplex Slidex~-staph monoclonal antibody examinated to SA and confirmed to MRSA has higher sensitivity and specificity.
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OBJECTIVE To investigate characters of molecular epidemiology of meticillin-resistant Staphylococcus aureus(MRSA) outbreak strains in an emergency intensive care unit(EICU),to follow-up the possible sources,understand transmission for infection,and determine preventive strategies.METHODS Pulsed-field gel electrophoresis(PFGE) was used to analyze the homology of MRSA strains,isolated from clinical patients′ infection sites and environment,and carried by patients and healthcare workers in EICU of our hospital in December,2004.RESULTS Six of 17 patients were infected by MRSA,and 7 strains were isolated((including) 2 strains from different sites of the same patient).Surveillance cultures of ward′s environments,(patients)′ nares and healthcare workers′ nares and hands were performed in the outbreak period.Five MRSA strains were isolated,including a strain from nares of a patient,a strain from a table-board of a procedure room,a strain from hand of a nurse,a strain from a bed bar,and a strain from ward′s air.PFGE typing of the 12 MRSA strains showed that all 7 strains isolated from patients′ infection sites and two strains from nares of a patient and hand of a nurse were of type A.Strains from a procedure room,bed bar and air were of types B,C and D,respectively.CONCLUSIONS MRSA′s source and its transmission route are elucidated by genotyping.MRSA appears to come from a patient′s nares and has been transferred in ward by hand of healthcare workers.
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OBJECTIVE To study the epidemiology of the drug-resistant genes in meticillin-resistant coagulase negative staphylococcus(MRCNS).METHODS mecA,aac(6′)/aph(2″) and aph(3′)-Ⅲgenes of aminoglycoside-modifying enzyme(AME) and ermA/B/C genes of erythromycin methyltransferase were detected by polymerase chain reaction(PCR) from 40 MRCNS strains.RESULTS Thirty-nine strains carried mecA gene,32 strains with aac(6′)/aph(2″) gene,15 strains with aph(3′)-Ⅲ gene,30 strains with ermA/B/C gene and 2 strains with tetM gene in 40 MRCNS strains.CONCLUSIONS About 65% MRCNS strains carry mecA,aac(6′)/aph(2″),/aph(3′)-Ⅲ and ermA/B/C genes at the same time.
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OBJECTIVE To screen the anti-meticillin-resistant Staphylococcus aureus(MRSA)traditional Chinese materia medica(TCMM)by biosensor technique,targeted on the soluble penicillin binding protein 2a(PBP2a)of clinical MRSA.METHODS The soluble PBP2a with amino acid sequence from 25 to 668 from clinical MRSA were expressed in Escherichia coli by gene recombination technique.Then,the expressed product was identified and its biological function was analyzed.After the PBP2a was immobilized into the carboxymethyl dextran cuvette(CMD),the anti-MRSA TCMM was screened by means of biosensor.RESULTS The soluble protein PBP2a had been successfully expressed,whose relative molecular mass was 74?103.It was confirmed that the soluble PBP2a had transpeptidase activitiy and ?-lactamase activitiy.Subsequently,10 kinds of anti-MRSA TCMM were screened out by biosensor technique.Moreover,Radix Scutellariae,Rhizoma Coptidis and Spica Prunellae had greater anti-MRSA effect than others.CONCLUSIONS Anti-MRSA TCMM has been successfully screened out by biosensor technique,targeted on the soluble PBP2a of clinical MRSA.
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OBJECTIVE To investigate the genotypes of meticillin-resistant Staphylococcus aureus(MRSA)and its resistance.METHODS A total of 73 MRSA clinical isolates were collected in Anhui Province,MIC of sixteen different antibacterial agents against the isolates were determined by agar dilution method.PCR amplified the mec associated hypervariable region(HVR)of MRSA,and the genotypes were classified based on the fragments of amplified products.The correlation of genotypes and antimicrobial resistance was analyzed.RESULTS Seventy three strains of MRSA from Anhui Province were grouped into A,B and C genotypes based on HVR polymorphism,and respectively 17.8%,23.3%,and 58.8%.All strains were sensitive to vancomycin.CONCLUSIONS MRSA is multi-drug resistant and can be divided into 3 genotypes based on the HVR PCR amplified products.HVR PCR method is a rapid and convenient method for molecular epidemiology study of MRSA infections.