Comparison of Latex Agglutination Test with Polymerase Chain Reaction for Detection of mecA Gene in Methicillin Resistant Staphylococcus aureus

Background: Antimicrobial resistance is a devastating question that threatens health globally. The extensive, indiscriminate and unnecessary consumption of antibiotics for humans, as well as wildlife and in agriculture; lead to the development of notoriously resistant Staphylococcus aureus; through possession of mecA gene, encoded by modified Penicillin binding protein (PBP2a); being labeled “Methicillin resistant Staphylococcus aureus”. Conventional phenotypic techniques for MRSA detection rely on standardization of cultural characteristics. The latex agglutination method can be adopted as an accurate strategy for rapid detection of MRSA. Methodology: A total of 713 consecutive, non-duplicate isolates of Staphylococcus aureus were processed. Methicillin resistance was determined using cefoxitin (30 µg) by Kirby-Bauer method following Clinical and Laboratory Standards Institute (CLSI) guideline, latex agglutination method; and PCR for mecA gene. Results: The results showed that out of 713 Staphylococcus aureus isolates, 12.90% isolates were detected as MRSA due to resistance to cefoxitin. By latex agglutination method, 87 (94.50%) were positive for PBP2a; while on PCR mecA gene was detected only in 82 (89.10%) MRSA isolates. When assessed with PCR (gold standard) the sensitivity and diagnostic accuracy of latex agglutination was 100% and 94.57%, respectively. Conclusion: Latex agglutination test can be used as a prompt and reliable diagnostic technique for mecA gene detection in MRSA isolates, where molecular methods are limited. This can effectively minimize the misdiagnosis of resistant strains, and over/misuse of antibiotics.

Clinico-microbiological analysis of toxigenic clostridium difficile from hospitalised patients in a tertiary care hospital, Mangalore, Karnataka, India

Purpose: Prevalence of Clostridium difficile, an anaerobic, Gram-positive, spore-forming bacillus, is very much underestimated in India. The present study was intended to assess the burden of toxigenic C. difficile in hospitalised patients with clinically significant diarrhoea and analysis of their clinical picture. Materials and Methods: This cross-sectional study was conducted in a tertiary care teaching hospital, South India, from January 2012 to December 2014. Stool samples were collected consecutively from 563 inpatients from various wards. The prevalence of toxigenic C. difficile was determined by toxigenic culture and a two-step algorithm. The clinical spectrum of these patients was also analysed. Associated pathogens were identified using standard procedures. Statistical analysis was done by frequency, percentage, Chi-square test and z-test. Results: Out of the 563 stool samples analysed, the prevalence of toxigenic C. difficile was 12.79% and that of non-toxigenic C. difficile was 10.83%. The prevalence of toxigenic C. difficile among oncology patients was highly significant (HS). Antibiotic treatment, prolonged hospital stay and underlying diseases/conditions were the risk factors which were HS, and fever was the significant clinical feature among the patients. Escherichia coli was the predominant associated pathogen isolated (18.47%). Conclusion: The presence of toxigenic C. difficile in our locality is a matter of concern. Constant supervision, appropriate treatment and preventive measures are crucial in controlling C. difficile infection.

A Comparative Analysis of Different Phenotypic Methods Used in \r\nDetection of Methicillin Resistant Staphylococcus Aureus\r\n

Introduction: In developing country like Bangladesh rheumaticfever is common diseases occur in children.Objective: In this study our main goal is to evaluate theincidence in rheumatic fever in age 5-15 age groupBangladesh.Method: This cross sectional study was done at differentprivate hospital in Khulna district from January 2016 to January2017 .where 100 patients data were recorded methodically in apreformed data sheet.Results: In the study 71% patients’ mother was illiterate andmost of them were house wife. Also, most of the patients facedserious heart damage.Conclusion: We can conclude that, overcrowding and lowattainment of education by mothers is responsible for incidenceof RF in children. Further study in needed for better outcome.

Ceftaroline resistance in Staphylococcus pseudintermedius gene mecA carriers / Resistência à ceftarolina em Staphylococcus pseudintermedius portadores do gene mecA

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) being a constant concern, ceftaroline fosamil has been recently approved as a new cephalosporin, active against MRSA, for use in humans; only rare cases of resistance have been reported till date. There is no report of resistance to ceftaroline in Staphylococcus pseudintermedius, which is the main bacterium causing dermatitis and otitis in dogs. To evaluate staphylococcal resistance to ceftaroline, 35 isolates of methicillin-resistant S. pseudintermedius (MRSP), carrying the mecA gene, from 26 dogs with folliculitis and nine dogs with external otitis, underwent disk diffusion test with cefoxitin, oxacillin, and ceftaroline. Tests with cefoxitin and oxacillin showed > 90% sensitivity in methicillin resistance detection. In the disk diffusion test, 97.14% (34/35) were resistant to cefoxitin, 94.29% (33/35) to oxacillin, and 31.43% (11/35) to ceftaroline. Of the ceftaroline-resistant strains, 27.27% (3/11) were obtained from the ears of dogs while the rest (8/11) were from the skin. The current report is the first description of MRSP resistance to ceftaroline.(AU)

Infecções causadas por Staphylococcus aureus resistente à meticilina (MRSA) são uma preocupação médica constante. A ceftarolina fosamila é uma nova cefalosporina ativa contra Staphylococcus aureus resistente à meticilina recentemente aprovada para uso em humanos e raros casos de resistência relatados até agora. Não há relatos de resistência à ceftarolina em Staphylococcus pseudintermedius, principal bactéria causadora de dermatite e otite em cães. Com o objetivo de avaliar a resistência estafilocócica à ceftarolina, 35 amostras de S. pseudintermedius resistentes à meticilina (MRSP), portadoras do gene mecA, provenientes de 26 cães com foliculite e 9 com otite externa foram submetidos ao teste de disco-difusão com cefoxitina, oxacilina e ceftarolina. Os testes realizados com cefoxitina e oxacilina mostraram mais de 90% de sensibilidade na detecção da resistência à meticilina em ambas. No teste da disco-difusão, 97,14% (1/35) foram resistentes à cefoxitina, 94,29% (3/35) à oxacilina e 31,43% (11/35) à ceftarolina. Das cepas resistentes às ceftarolina, 27,27 (3/11) foram provenientes de ouvido de cães e as demais (8/11), provenientes da pele, sendo essa primeira descrição de resistência de MRSP à ceftarolina na literatura atual.(AU)

Cefoxitin plus levofloxacin for prevention of severe infection after transrectal prostate biopsy / 中华男科学杂志

<p><b>Objective</b>To evaluate the effect of cefoxitin prophylactic in reducing the incidence of severe infection after transrectal prostate biopsy (TRPB).</p><p><b>METHODS</b>This retrospective study included 155 cases of TRPB with a 5-day administration of oral levofloxacin at 200 mg bid (the control group) and another 167 cases with a 3-day administration of oral levofloxacin at the same dose plus intravenous cefoxitin at 2.0 g 2 hours before TRPB (the experimental group) according to the distribution characteristics of drug-resistance bacteria in our department. The patients of the control and experimental groups were aged (68.68 ± 8.12) and (68.72 ± 7.51) years, with PSA levels of (19.78 ± 21.57) and (21.15 ± 42.63) μg/L, involving (11.68 ± 1.44) and (11.77±1.02) biopsy cores, respectively. Comparisons were made between the two groups of patients in the incidence rate of severe infection, which was defined as lower urinary track symptoms plus the systemic inflammatory response syndrome (SIRS) within 7 days after TRPB.</p><p><b>RESULTS</b>The incidence rate of postoperative severe infection was significantly lower in the experimental group than in the control (0.6% ［1/167］ vs 5.8% ［9/155］, P < 0.05). Blood cultures revealed positive E-coli strains in 6 cases in the control group, including 5 ESBL-positive and 4 quinolone-resistant and amikacin-sensitive cases, all sensitive to cefoxitin, cefoperazone/sulbactam and imipenem. The only one case of severe infection was shown to be negative in blood culture.</p><p><b>CONCLUSIONS</b>Preoperative intravenous administration of cefoxitin according to the specific distribution characteristics of drug-resistance bacteria can significantly reduce the incidence of severe infection after TRPB.</p>

Clinical effect of cefoxitin sodium combined with Kangfuyan capsules in the treatment of pelvic inflammatory disease and its influence on inflammatory cytokines / 中国基层医药

Objective To investigate the clinical effect of cefoxitin sodium combined with Kangfuyan capsules in the treatment of pelvic inflammatory disease and its influence on inflammatory cytokines .Methods According to the random number table method ,450 cases with chronic pelvic inflammatory disease were divided into the observation group and the control group ,225 cases in each group .The observation group was given cefoxitin sodium combined with Kangfuyan capsules treatment ,the control group received cefoxitin sodium therapy .The treatment effect and the changes of inflammatory cytokines before and after treatment were compared between the two groups .Results The total effective rate(93.3％vs.86.7％) and the cure rate(66.7％vs.53.5％) of the observation group were signif-icantly higher than those of the control group ,the differences were statistically significant (χ2 =8.333,5.556,all P<0.05).After treatment,the TNF-alpha,IL-6 and CRP levels in the two groups were significantly decreased ,which of the observation group were better than those of the control group [(43.7 ±18.2)ng/L vs.(53.2 ±21.6)ng/L, (323.8 ±124.6)ng/L vs.(399.5 ±141.3)ng/L,(9.7 ±3.5)mg/L vs.(13.4 ±5.9)mg/L],the differences were statistically significant(t=7.865,5.783,4.517,all P<0.05).Conclusion Cefoxitin sodium combined with Kang-fuyan capsule in the treatment of chronic pelvic inflammatory disease ,can significantly improve the treatment effect , improve the level of inflammatory cytokines .

Staphylococcus aureus y estafilococo coagulasa negativa resistentes a la meticilina / Staphylococcus aureus and negative coagulase staphylococcus resistant to methicillin

Se realizó un estudio prospectivo de 47 cepas de estafilococo procedentes de muestras biológicas del Laboratorio de Microbiología del Hospital Provincial Docente Clinicoquirúrgico Saturnino Lora Torres de Santiago de Cuba, desde febrero hasta abril de 2017, con vistas a determinar la frecuencia de estafilococos resistentes a la meticilina. En la serie, el mayor número de los aislamientos correspondió a las muestras de secreciones y catéter; asimismo, los servicios con mayores aislamientos notificados fueron Ortopedia y Cirugía. Se observó una frecuencia elevada de cepas de Staphylococcus aureus y estafilococo coagulasa negativa, resistentes a meticilina

A prospective study of 47 staphylococcus stumps coming from biological samples of the Microbiology Laboratory in Saturnino Lora Torres Teaching Clinical Surgical Provincial Hospital was carried out in Santiago de Cuba, from February to April, 2017, aimed at determining the frequency of staphylococcus resistant to methicillin. In the series, the highest number of isolations corresponded to the samples of secretions and catheter; also, the services with more notified isolations were Orthopedics and Surgery. A high frequency of Staphylococcus aureus stumps and negative coagulase staphylococcus resistant to methicillin was observed

Tipificación SARM en trabajadores asistenciales de las unidades de cuidados intensivos en una institución hospitalari / MRSA Typing in health care workers from intensive care units of a Hospital Institution

Objetivo. Caracterizar microbiológicamente SARM en trabajadores asistenciales de las Unidades de Cuidados Intensivos en una institución hospitalaria de la ciudad de Montería. Materiales y métodos. Se realizó un estudio descriptivo longitudinal, en 52 trabajadores de dos unidades de cuidado intensivo; se tomaron hisopados nasales y faríngeos a cada individuo, con una periodicidad de 15 días/cinco meses. Mediante pruebas convencionales como fermentación de manitol, catalasa y coagulasa se realizó la identificación de S. aureus, con el disco de cefoxitín por Kirby- Bauer se evaluó la resistencia a Meticilina mediada por el gen mecA; antibióticos como Vancomicina, Eritromicina y Clindamicina fueron evaluados por esta prueba y confirmados por MicroScan ®. Resultados. se obtuvieron 88 aislamientos de S. aureus y 21 aislamientos SARM, una prevalencia de portación de SARM del 25%. El 90,5 % de las cepas de SARM fueron recuperadas de la faringe, en mayor proporción (50%) en el personal de enfermería. Conclusiones. La evidencia de su circulación de SARM en el personal asistencial dentro de una institución hospital, genera una alerta que le permite a la misma establecer políticas de contención para evitar la diseminación de estas cepas y evitar la aparición de brotes o infecciones hospitalarias asociadas a este patógeno.

Objective. To characterize microbiologically MRSA in health care workers of the Intensive Care Units at a hospital institution in the city of Montería. Materials and methods. A longitudinal descriptive study was carried out in 52 workers from two intensive care units; nasal and pharyngeal swabs were taken from each individual, with a periodicity of 15 days / five months. Examined through microbiological methods such as fermentation of mannitol, catalase and coagulase the identification of S. aureus was performed, with the cefoxitin disc by Kirby-Bauer disc-diffusion method the methicillin resistance mediated by the mecA gene was evaluated; antibiotics such as Vancomycin, Erythromycin and Clindamycin were evaluated by this test and confirmed by MicroScan ®. Results. we obtained 88 isolates of Staphylococcus aureus and 21 MRSA, a prevalence of MRSA of 25%. 90.5% of strains Of SARM were recovered from the pharynx, in a greater proportion (50%) in nursing staff. Conclusions. Evidence of MRSA circulation in care staff within a hospital institution generates an alert that allows it to establish containment policies to avoid the dissemination of these strains and to avoid the appearance of outbreaks or hospital infections associated with this pathogen.

Rationality Evaluation of Cefoxitin Use in Our Hospital by AHM Weighted TOPSIS Method / 中国药房

OBJECTIVE:To evaluate the rationality of cefoxitin use in our hospital. METHODS:Evaluation index and evalua-tion criteria were established on the basis of DUE. The relative weight of evaluation index were calculated by using attribute-based AHM weight method,and the gas between medical orders and complete rational ones were evaluated by using TOPSIS processing method. The proportion of rational medical orders were calculated to evaluate the rationality of drug use. RESULTS:Among 116 medical records,there were 19%reasonable medical orders(including 4.3%complete reasonable medical orders,5 cases),50%ba-sically reasonable medical orders(58 cases)and 31% unreasonable medical orders(36 cases). CONCLUSIONS:It is reasonable and feasible to use AHM weighted TOPSIS method to evaluate the rationality of cefoxitin. The utilization of cefoxitin in our hospital is basically reasonable,but there are still many problems.

Genotypic and phenotypic characterization of methicillin resistance determinants and β-lactamase in Staphylococcus species

Aims: To characterize the genotypic distribution of mec complex, bla complex, methicillin-resistance level (cefoxitinMIC) and β-lactamase activity in carriage methicillin-resistant Staphylococcus species for a potential correlation. Methodology and results: Biochemical test, 30 µg cefoxitin diffusion disc test, cefoxitin E-test, mec and bla complexes distributions, Pbp2a and β-lactamase assays were conducted to characterize phenotypic and genotypic of MRSA and MRCoNS in our collection. Phylogenetic tree was constructed using MEGA6 software to trace the diversity of blaZ gene of MRSA and MRCoNS. Sixteen MRSA and nineteen MRCoNS were identified by biochemical tests followed by 30 µg cefoxitin antibiotic disc susceptibility test and mecA gene screening. Twenty nine isolates carry complete mecA genes (2.1 kb), incomplete mec regulator (negative or truncated) and positive Pbp2a assay for both MRSA and MRCoNS. Only MRCoNS SC177 isolate with cefoxitin MIC of 32 µg/mL carries complete mec complex. Thirty-one of thirty-five isolates carry complete bla complex (blaZ, blaRI, blaI) with 10 MRSA produce strong β-lactamase and cefoxitin MIC of ≥12 µg/mL. Only 4 MRCoNS with cefoxitin MIC of ≤8 µg/mL produce strong β-lactamase. The diversity of blaZ gene was demonstrated by phylogenetic analysis and unusual amino acid mutation at position 145 for MRSA SA60 isolate may compromise its β-lactamase activity with low cefoxitin MIC level (2 µg/mL). Conclusions, significance and impact of the study: Isolates that carry complete complete mecA gene were largely consistent with the expression of Pbp2a. Nevertheless, there is no clear correlation of mec regulator genes in relation to cefoxitin-MIC in both methicillin resistant (MR) Isolates that carry Staphylococcus species. On the other hand, various expression level of β-lactamase may correlate with cefoxitin-MIC level in MRSA as compared to MRCoNS.

Comparative analysis of phenotypic and genotypic detection of methicillin resistance among Staphylococcus aureus.

Aims: Staphylococcus aureus is a common pathogen causing a wide range of infections ranging from mild skin and soft tissue infections to severe, life‑threatening infections. Accuracy in the detection of methicillin resistance is important to avoid treatment failures. The aim of this study was to compare the results of phenotypic and genotypic test methods to detect methicillin resistance and also to determine the antimicrobial susceptibilities. Materials and Methods: Two hundred and forty‑two S. aureus strains isolated from skin and soft tissue samples were analyzed for methicillin resistance using oxacillin and cefoxitin disk diffusion (DD), oxacillin screen agar test, cefoxitin E‑test, and mecA gene polymerase chain reaction (PCR). Results: 77 of 242 S. aureus isolates were mecA positive. Oxacillin, cefoxitin DD, oxacillin screen agar test and cefoxitin E‑test exhibited sensitivities as 98.7%, 98.7%, 100%, 100%, and specificities as 96.9%, 97.5%, 96.9%, 97.5%, respectively. Conclusion: Results of oxacillin screen agar and cefoxitin DD test were in concordance with mecA gene PCR. Thus, it is determined that especially cefoxitin test can be an alternative to PCR in routine.

Study of variables involved in hospital-acquired urinary tract infections at a university hospital / Estudo de variáveis envolvidas em infecção do trato urinário nosocomiais em um hospital universitário

OBJECTIVE: Analyze bacteria involved in urinary tract nosocomial infections (UTIs), their sensitivity profile, and other correlated clinical variables. METHODS: This was a retrospective study, based on the analysis of positive urine culture reports (from100,000CFU/ml) for nosocomial infection covering the years 2009, 2010 and 2011, and on medical records. Statistical analysis was performed through SPSS 19.0 software, using chi-square tests with Yates correction and Pearson's correlation coefficient. p<0.05 was considered statistically significant. RESULTS: The sample consisted of 74 positive urine cultures, 64.9% of which from females, and 58.1% of which from patients above 50 years of age. Medical conditions accounted for 87.8% of cases, and nervous and gastrointestinal problems were the most prevalent. Hospital stay ranged from 56.7±35.7 days; 51.4% of the patients used indwelling urinary catheter, 54% of whom over a 30 day period. Klebsielle pneumoniae and Escherichia coli together accounted for 60.8% of cases. Amikacin, Gentamicin, Cefoxitin, Piperacillin-tazobactam, Imipem, Meropenem and Ertapenem showed ≥50% sensitivity. There were correlations between symptoms associated to UTI and antibiotic use after urine culture (p=0.02), and catheter use and duration of hospital stay (p=0.04). CONCLUSIONS: Female patients over 50 years of age with underlying clinical conditions originated in the nervous system or the gastrointestinal apparatus making use of indwelling urinary catheters for over 30 days and a hospital stay period of 56.7±35.7 days are more likely to develop nosocomial UTIs. Amikacin, Gentamycin and Cefoxitin are feasible options for empirical antibiotic therapy against the two most prevalent bacteria.

OBJETIVO: Analisar as bactérias envolvidas nas infecções do trato urinário (ITUs) nosocomiais, perfil de sensibilidade, e outras variáveis clínicas correlacionadas. MÉTODOS: Estudo retrospectivo, com base na análise dos laudos de urocultura positiva (a partir de 100 mil UFC/ml) para infecção nosocomial abrangendo os anos 2009, 2010 e 2011, em prontuários médicos. A análise estatística foi realizada no SPSS 19.0, utilizando os testes do qui-quadrado com correção de Yates e coeficiente de correlação de Pearson. Considerou-se estatisticamente significativo p<0,05. RESULTADOS: A amostra constitui-se de 74 uroculturas positivas, sendo 64,9% do sexo feminino, com 58,1% acima de 50 anos. As patologias clínicas corresponderam a 87,8% dos casos, sendo sistema nervoso e gastrointestinal os de maiores prevalências. Tempo de permanência hospitalar foi de 56,7±35,7 dias, 51,4% fizeram uso de SVD, sendo 54% destes com uso acima de 30 dias. As bactérias Klebsielle pneumoniae e Escherichia coli representaram juntas 60,8% dos casos. Os antibióticos Amicacina, Gentamicina, Cefoxitina, Piperaciclina-tazobactam, Imipem, Meropenem e Ertapenem apresentaram sensibilidade ≥50%. Houve correlação entre sintomas associados à ITU e uso de antibiótico após urocultura (p=0,02); tempo de uso de sonda e tempo de permanência hospitalar (p=0,04). CONCLUSÕES: Pacientes femininos com mais de 50 anos e doença de base clínica, de origem no sistema nervoso ou gastrointestinal, em uso de SVD por mais de 30 dias e tempo de permanência hospitalar de 56,7±35,7 dias, estão entre as mais propensas a desenvolverem ITU nosocomial. A Amicacina, Gentamicina e Cefoxitina apresentaram opções factíveis para a antibioticoterapia empírica as duas bactérias mais prevalentes.

Cost-effectiveness Analysis of Levofloxacin and Cefoxitin in the Treatment of Adult Non-severe Communi-ty-acquired Pneumonia / 中国药房

OBJECTIVE:To evaluate and compare cost-effectiveness of levofloxacin and cefoxitin in the treatment of adult non-severe community-acquired pneumonia(CAP). METHODS:71 cases of adult non-severe CAP were selected and divided into levofloxacin group (group A,33 cases) and cefoxitin group (group B,38 cases). Gronp A received Mesylate levofloxacin injec-tien 200 ml inotraveously,once a day;group B received Cefoxitin for injection 2.0 g intravenously,3 times a day,for 8 days. Clinical efficacy,excellence time and ADR of 2 groups were observed,and cost-effectiveness analysis was conducted. RESULTS:The total effective rate of group A and group B were 87.88% and 65.79%,and excellence time(5.53±2.56)d and(3.87±3.03)d, with statistical significance(P0.05). The total costs were 6 748.93 yuan and 8 110.34 yuan;the cost-effectiveness ratios were 76.80 and 123.28;incremental cost-effectiveness ratio was -61.63%. Results of sensitivity analysis matched results of cost-effectiveness analysis. CONCLU-SIONS:Levofloxacin save more and is economical in the treatment of adult non-severe CAP.

The retrospective study of oxacillin susceptible, mecA positive Staphylococcus aureus in China / 中华检验医学杂志

Objective The purpose of the study is to understand the epidemiology,distribution and molecular characteristics of oxacillin susceptible mecA positive Staphylococcus aureus (S.aureus).Methods Totally 1588 S.aureus isolates collected from 12 hospitals in 10 cities of China between 2010 and 2012 were retrospectively characterized.The isolates were characterized by antimicrobial susceptibility test of 20antimicrobial drugs.Three different methods (cefoxitin disc diffusion,agar dilution for oxacillin and cefoxitin) to detect oxacillin susceptible and mecA positive S.aureus were also compared.All the strains were confirmed to be S.aureus by detecting S.aureus specific genes by PCR (including nuc,femB,and mecA gene),which was viewed as the golden standard of MRSA.The molecular typing methods included SCCmec and spa typing.The statistical analyses were carried out in statistical product and service solutions (SPSS),Version 18.0.The significance level P was set at 0.05.Results According to the MICs of cefoxitin and oxacillin,a total of 60 isolates were oxacillin susceptible methicilin resistance Staphylococcus aureus (MRSA).Based on the differences of the specimen collection date,it is found that oxacillin susceptible MRSA have increased from 2010 to 2012 (P =0.05,95％ CI 0.045-0.056,X2 =6.099).These isolates were distributed in 9 major cities,and the highest prevalence is 30.0％ (18/60) in Guangzhou,followed by Beijing (18.3％,11/60),Wuhan (15.0％,9/60),Hangzhou (13.3％,8/60).Most of the isolates were from skin soft tissue infection (35％,21/60),blood stream infection (30％,18/60) and respiratory infection specimens (18.3％,11/60).The resistance rate to cefoxitin,erythromycin,clindamycin and tetracycline was 100％ (60/60),86.7％ (52/60),66.7％ (40/60) and 50％ (30/60),respectively.The molecular characterization showed that 21 spa and 5 SCCmec types were detected.The most predominant clone was spa t437-SCCmec Ⅳ (25.0％,15/60),followed by spa t437-SCCmecV (13.3％,8/60).Conclusions The detection rate of oxacillin susceptible MRSA is significantly higher from 2010 to 2012.The major clone is t437-SCCmec Ⅳ.The use of cefoxitin should replace oxacillin in detecting this type of MRSA.Further study is needed to confirm whether beta lactam antimicrobial agents should be used in the treatment of oxacillin susceptible mecA positive S.aureus.

Evaluation of real-time fluorescent quantitative PCR and cefoxitin screening test in detection of methicillin-resistant Staphylococcus aureus / 国际检验医学杂志

Objective To evaluate the cefoxitin screening test in detecting(MRSA)with the real-time fluorescent quantitative polymerase chain reaction(RT-PCR)for detecting mecA gene as the golden standard.Methods Staphylococcus aureus strains iso-lated from various bacterial infection specimens were collected,which were amplified by RT-PCR and detected by the cefoxitin screening test respectively.The results were compared.Results In 121strains of MRSA,66 strains carrying mecA gene were detec-ted by RT-PCR(P >0.05),accounting for 54.55%(66/121).There was no statsitcal difference in the detection results between the cefoxitin screening test and RT-PCR.The sensitivity of the cefoxitin screening test was 93.93%,the specificity was 81.82%,the positive predictive value was 84.93% and negative predictive value was 91.83%.Conclusion The RT-PCR technique can accurate-ly and rapidly detect MRSA.

Application analysis of double-disk synergy test in AmpC β-lactamase detection / 国际检验医学杂志

Objective To investigate and analyze the double-disk inhibiting synergy test for detecting AmpC β-lactamase pro-duced by Klebsiella pneumoniae and to evaluate its application value in clinical laboratory.Methods The cefoxitin disk agar diffu-sion method,cefoxitin three-dimensional method,double-disk inhibiting synergy test and drug resistance gene multiplex PCR assay were adopted to detect the clinically isolated bacterial strains.Results Among 137 clinically isolated strains of Klebsiella pneumoni-ae,22 strains were insensitive to cefoxitin and 11 strains were positive by the three-dimensional method;in the double-disk inhibiting synergy test,18 strains were positive for the FOX/FOX+PBA group and 11 strains were positive for the CTT/CTT+PBA group respectively;in the multiplex PCR assay,19 strains were positive.The coincidence rate of the cefoxitin three-dimensional method and multiplex PCR methods was 47.4%(9/19),in the double-disk inhibiting synergy test,the coincidence rate of the positive re-sults in the CTT/CTT+PBA group and the multiplex PCR methods was 57.9%(11/19);the coincidence rate of the FOX/FOX+PBA group and multiplex PCR methods was 94.7%(18/19).Conclusion The double-disk inhibiting synergy test is simple with highly accurate results,in which the FOX/FOX+PBA double-disk synergy test could be applied to detect AmpC β-lactamase pro-duced by clinical isolates of Klebsiella pneumoniae.

Comparison of cefoxitin disk diffusion test and mecA gene PCR results for methicillin resistance detection in Staphylococcus intermedius group isolates from canine origin in Brazil

The study evaluated cefoxitin disk diffusion tests breakpoints and their correlation to mecA gene PCR results for detecting Methicillin-resistant Staphylococcus intermedius Group (MRSP) isolates from dogs in Brazil. Agreement using proposed breakpoint (resistant < 30 mm) was encouraging. The current study reinforces that an epidemiological breakpoint can be established to predict presence of MRSP.

Comparison of five methods for oxacillin susceptibility testing of Staphylococcus aureus isolates from cystic fibrosis patients / Comparação entre cinco métodos para avaliação de susceptibilidade à oxacilina em cepas de Staphylococcus aureus isoladas de pacientes com fibrose cística

Methicillin-resistant Staphylococcus aureus (MRSA) are now a worldwide problem. Cystic fibrosis (CF) patients are commonly colonized and infected by MRSA. Accurate oxacillin susceptibility testing is mandatory for the adequate management of these patients. We performed a comparison of the accuracy of different tests in CF isolates, including methicillin-susceptible S. aureus and MRSA with different SCCmec types, and using the mecA gene as the gold-standard. The sensitivity and specificity of oxacillin disc, Etest, and oxacillin agar screening plate were 100%. Sensitivity of the cefoxitin disc was 85% and specificity was 100%. For clinically relevant isolates, laboratories may consider the use of a combination of two phenotypic methods.

Staphylococcus aureus resistentes à oxacilina (MRSA) são, atualmente, um problema global. Pacientes com fibrose cística (FC) são frequentemente colonizados e infectados por MRSA. A realização de testes de susceptibilidade acurados é extremamente importante para o manejo da terapia antimicrobiana nesses indivíduos. Nesse estudo, realizamos comparação entre as acurácias de diversos testes de susceptibilidade à oxacilina, em cepas de S. aureus isoladas de pacientes com fibrose cística, tanto sensíveis como resistentes à oxacilina, com diferentes tipos de SCCmec, e utilizando a detecção do gene mecA como método padrão. A sensibilidade e a especificidade do disco de oxacilina, do Etest, e da placa de agar screening com oxacilina foram de 100%. A sensibilidade do disco de cefoxitina foi 85%, com especificidade de 100%. Em cepas clinicamente relevantes, a utilização combinada de mais de um método deveria ser considerada.

Phenotypic & molecular characterization of AmpC β-lactamases among Escherichia coli, Klebsiella spp. & Enterobacter spp. from five Indian Medical Centers.

Background & objectives: AmpC β-lactamases which are often plasmid mediated hydrolyze all β-lactam antibiotics except cefepime and carbapenems. We evaluated the presence of AmpC β-lactamases among Enterobacteriaceae strains recovered prospectively from patients at five Indian tertiary care centres. Methods: The study included 909 consecutive Gram-negative isolates recovered from clinically significant specimens during June 2007 - May 2008 as part of an ICMR-ESBL study. Among the study isolates, 312 were found to be cefoxitin resistant by disc diffusion test (DDT). Minimum inhibitory concentration (MIC) determination by E test was done against amikacin, levofloxacin, impinem, meropenem, ertapenem, tigecycline and piperacillin-tazobactam. Combined DDT using phenyl boronic acid as inhibitor with cefoxitin was used for phenotypic confirmation of AmpC phenotype. The common Amp C genotypes ACC, FOX, MOX, DHA, CIT and EBC were detected by multiplex PCR. Results: Plasmid mediated Amp C phenotype was confirmed in 114 of the 312 (36.5%) cefoxitin resistant isolates with 255 (81.7%) showing multidrug resistance. Susceptibility to tigecycline was highest (99%) followed by imipenem, meropenem (97%), ertapenem (89%), amikacin (85%), and piperacillin-tazobactam (74.6%). Levofloxacin resistance was 82 per cent. ESBL co carriage was observed among 92 per cent of Amp C producers. Among 114 Amp C producers, 48 could be assigned a genotype, this included CIT- FOX (n=25), EBC (n=10), FOX (n = 4), CIT (n=3), EBC-ACC (n=2) and one each of DHA, EBC-DHA, FOX -DHA and FOX-EBC-DHA. Interpretation & Conclusions: Overall, AmpC phenotypes were found in 12.5 per cent isolates, multidrug resistance and ESBL co-carriage among them was high suggesting plasmid mediated spread. The study results have implications in rational antimicrobial therapy and continued surveillance of mechanisms of resistance among nosocomial pathogens.