RESUMO
Antibacterial susceptibility testing (AST) is performed to guide therapy, perform resistance surveillance studies, and support development of new antibacterial agents. For 5 decades, broth microdilution (BMD) has served as the reference method to assess in vitro activity of antibacterial agents against which both novel agents and diagnostic tests have been measured. BMD relies on in vitro inhibition or killing of bacteria. It is associated with several limitations: it is a poor mimic of the in vivo milieu of bacterial infections, requires multiple days to perform, and is associated with subtle, difficult to control variability. In addition, new reference methods will soon be needed for novel agents whose activity cannot be evaluated by BMD (e.g., those that target virulence). Any new reference methods must be standardized, correlated with clinical efficacy and be recognized internationally by researchers, industry, and regulators. Herein, we describe current reference methods for in vitro assessment of antibacterial activity and highlight key considerations for the generation of novel reference methods.
Assuntos
Antibacterianos , Humanos , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologiaRESUMO
A vast amount of antimicrobial susceptibility test (AST) data is generated from routine testing in diagnostic laboratories for the primary purpose of guiding clinicians in antimicrobial therapy decisions for their patients. However, there is additional value for these data when they are compiled at the local, regional, national, and global levels. Cumulative AST data can be used to prepare antibiograms at the individual health care facility level. These reports can be used to gain insight into appropriate empirical therapy options prior to the availability of AST results on an individual patient's isolate. Different types of cumulative AST data reports can also be compiled at the regional, national, and global levels to estimate susceptibility rates in geographic regions, document trends in evolving microbial populations, and recognize the appearance and spread of emerging antimicrobial resistance threats. The first CLSI M39 Guideline for Analysis and Presentation of Cumulative AST Data was published in 2000. Since that time, there have been changes to AST and reporting recommendations as well as the introduction of advanced informatics technologies to analyze and present data. The 5th edition of M39 has taken into consideration these changes to assist those who analyze, present, and utilize routine antibiograms and other types of cumulative AST data reports as well as those who design information systems for the capturing and analyzing of AST data. Furthermore, antimicrobial stewardship programs (ASPs) have expanded considerably, and uses of the antibiogram by ASPs have been addressed. This minireview will remind users of the basic recommendations for analysis and presentation of antibiograms and provide new suggestions to enhance these reports.
Assuntos
Antibacterianos , Laboratórios , Humanos , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Instalações de SaúdeRESUMO
The Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing (AST) develops and publishes standards and guidelines for AST methods and results interpretation in an annual update to the Performance Standards for Antimicrobial Susceptibility Testing (M100). This minireview will discuss changes to M100 for the 31st edition, including new and revised breakpoints and testing recommendations. New MIC and disk diffusion breakpoints are described for azithromycin (Shigella spp.), imipenem-relebactam (Enterobacterales, Pseudomonas aeruginosa, and anaerobes), and lefamulin (Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae), and disk breakpoints are described for azithromycin and Neisseria gonorrhoeae. The rationale behind revised oxacillin MIC breakpoints for select staphylococci is discussed. Updates to test methods include a method for disk diffusion using positive blood culture broth and use of linezolid to predict tedizolid susceptibility. There is clarification on which drugs to suppress on bacteria isolated from the cerebrospinal fluid and clarification on the use of a caret symbol attached to the intermediate category ("I^") to indicate those antimicrobials that concentrate in the urine.
Assuntos
Laboratórios , Oxacilina , Antibacterianos/farmacologia , Humanos , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosaRESUMO
Limited treatment options contribute to high morbidity/mortality rates with carbapenem-resistant, Gram-negative bacterial infections. New approaches for carbapenemase-producing organism (CPO) detection may help inform clinician decision-making on patient treatment and infection control. BD Phoenix CPO detect (CPO detect) detects and classifies carbapenemases in Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa during susceptibility testing. The clinical performance of CPO detect is reported here. Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa isolates were evaluated across three sites using CPO detect and a composite reference method (RM); the latter was comprised of the modified carbapenem inactivation method and a MIC screen for ertapenem, imipenem, and meropenem. Multiplex PCR testing was also utilized for Ambler class determination. Positive and negative percentages of agreement (PPA and NPA, respectively) between CPO detect and the RM were determined. The PPA and NPA for Enterobacterales were 98.5% (confidence intervals, 96.6%, 99.4%) and 97.2% (95.8%, 98.2%), respectively. The A. baumannii PPA and NPA, respectively, were 97.1% (90.2%, 99.2%) and 97.1% (89.9%, 99.2%). The P. aeruginosa PPA and NPA, respectively, were 95.9% (88.6%, 98.6%) and 92.3% (86.7%, 95.6%). The PPA values for carbapenemase class designations for all organisms combined and Enterobacterales alone, respectively, were 95.3% (90.2%, 97.8%) and 94.6% (88.8%, 97.5%) for class A, 94.0% (88.7%, 96.6%) and 96.4% (90.0%, 98.8%) for class B, and 95.0% (90.1%, 97.6%) and 99.0% (94.4%, 99.8%) for class D carbapenemases. NPA values for all organisms and Enterobacterales alone ranged from 98.5% to 100%. CPO detect provided accurate detection and classification of CPOs for the majority of isolates of Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa tested.
Assuntos
Antibacterianos , beta-Lactamases , Proteínas de Bactérias/genética , Humanos , Testes de Sensibilidade Microbiana , beta-Lactamases/genéticaRESUMO
In 2019, the Clinical and Laboratory Standards Institute (CLSI) published revisions to the Enterobacteriaceae ciprofloxacin and levofloxacin breakpoints. We evaluated the performance of disk diffusion and Etest compared to that of reference broth microdilution by use of the revised breakpoints. Fifty-eight Enterobacteriaceae isolates with ciprofloxacin MICs of 0.5 µg/ml or 1.0 µg/ml on initial testing were specifically selected for evaluation. These MICs are susceptible by the 2018 breakpoints and not susceptible by the 2019 breakpoints. For ciprofloxacin disk diffusion, the categorical agreement (CA) was 46.6%, with 0 very major errors (VME), 4 major errors (ME) (21.1%), and 27 minor errors (mE) (46.6%) using the 2019 CLSI disk breakpoints. For levofloxacin, the CA was 72.4%, with 0 VME, 0 ME, and 16 mE (27.6%) using the 2019 CLSI disk breakpoints. Using an error rate-bound evaluation method, levofloxacin but not ciprofloxacin disk diffusion yielded an acceptable minor error rate of <40% for isolates with an MIC plus or minus 1 doubling dilution of the intermediate breakpoint. For Etest compared to the reference broth microdilution, the essential agreement was 100% for both ciprofloxacin and levofloxacin and the CA was 81.0% and 65.5%, respectively. No VME or ME were observed by Etest, and 11 minor errors for ciprofloxacin (19.0%) and 20 (34.5%) for levofloxacin were observed. By the error rate-bound method, the minor error rate for ciprofloxacin was acceptable, but minor error rates for levofloxacin remained outside the acceptance range (i.e., 42.6% for isolates with an MIC within 1 dilution of the breakpoint). In general, the disk diffusion and Etest methods performed well with this challenging collection of isolates, although laboratories must be aware of minor errors, particularly for isolates with results near the breakpoint.
Assuntos
Antibacterianos/farmacologia , Ciprofloxacina/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Levofloxacino/farmacologia , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Farmacorresistência Bacteriana , Testes de Sensibilidade MicrobianaRESUMO
The Clinical and Laboratory Standards Institute (CLSI) has revised several breakpoints since 2010 for bacteria that grow aerobically. In 2019, these revisions include changes to the ciprofloxacin and levofloxacin breakpoints for the Enterobacteriaceae and Pseudomonas aeruginosa, daptomycin breakpoints for Enterococcus spp., and ceftaroline breakpoints for Staphylococcus aureus Implementation of the revisions is a challenge for all laboratories, as not all systems have FDA clearance for the revised (current) breakpoints, compounded by the need for laboratories to perform validation studies and to make updates to laboratory information system/electronic medical record builds in the setting of limited information technology infrastructure. This minireview describes the breakpoint revisions in the M100 supplement since 2010 and strategies for the laboratory on how to best adopt these in clinical testing.
Assuntos
Testes de Sensibilidade Microbiana/métodos , Testes de Sensibilidade Microbiana/normas , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Serviços de Laboratório Clínico/legislação & jurisprudência , Serviços de Laboratório Clínico/normas , Política de Saúde , Humanos , Estados Unidos , United States Food and Drug AdministrationRESUMO
Limited methods for colistin MIC determination are available to clinical microbiology laboratories. The purpose of this study was to evaluate the accuracy of the colistin broth disk elution (CBDE) test compared to that of broth microdilution (BMD) for identifying colistin MICs. CBDE was compared to colistin BMD using a collection of Gram-negative bacilli tested at two U.S. microbiology laboratories. The isolates tested included 121 retrospective clinical isolates, 45 prospective clinical isolates, and 6 mcr-1-positive Escherichia coli isolates. CBDE was performed with four 10-ml cation-adjusted Mueller-Hinton broth tubes per isolate, to which 0, 1, 2, and 4 colistin 10-µg disks were added, generating final concentrations in the tubes of 0 (growth control), 1, 2, and 4 µg/ml, respectively. MICs were evaluated visually and interpreted using Clinical and Laboratory Standards Institute breakpoints. Site 2 also compared CBDE to the reference broth macrodilution (BMAD) method (n = 110 isolates). Overall, CBDE yielded a categorical agreement (CA) and essential agreement (EA) of 98% and 99%, respectively, compared to the results of colistin BMD. Very major errors occurred for mcr-1-producing strains, with MICs fluctuating from 2 to 4 µg/ml on repeat testing. The results for all other isolates were in CA with those of BMD. CBDE versus BMAD had an EA of 100% and a CA of 100%. Compared to currently used techniques, CBDE is an easy and practical method to perform colistin MIC testing. Some mcr-1-producing isolates yielded MICs of 2 µg/ml by CBDE and 4 µg/ml by BMD. As such, the results for isolates with colistin MICs of 2 µg/ml by CBDE should be confirmed by the reference BMD method, and isolates with MICs of ≥2 µg/ml should be evaluated for the presence of mcr genes.
Assuntos
Antibacterianos/farmacologia , Colistina/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Testes de Sensibilidade Microbiana/métodos , Erros de Diagnóstico/estatística & dados numéricos , Bactérias Gram-Negativas/isolamento & purificação , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Estudos Prospectivos , Estudos Retrospectivos , Estados UnidosRESUMO
Background: The Clinical and Laboratory Standards Institute (CLSI) revised the carbapenem breakpoints for Enterobacteriaceae in 2010. The number of hospitals that adopted revised breakpoints and the clinical impact of delayed adoption has not been explored. Methods: We performed a cross-sectional, voluntary survey of microbiology laboratories from California acute care hospitals and long-term acute care hospitals (LTAC) to determine use of revised CLSI breakpoints. Carbapenem-resistant Enterobacteriaceae (CRE) clinical isolates from a single tertiary-care hospital from 2013 to 2017 were examined. All isolates with an elevated minimum inhibitory concentration (MIC; ≥2 µg/mL) to imipenem or meropenem were tested for the presence of carbapenemase genes by polymerase chain reaction (PCR). Results: We received responses from 128 laboratories that serve 264/393 (67%) of hospitals and LTACs. Current CLSI carbapenem breakpoints for Enterobacteriaceae were used by 92/128 (72%) laboratories. Among laboratories that used current breakpoints, time to implementation varied from 0 to 68 months (mean, 41 months; median, 55 months). Application of historical breakpoints to isolates with a carbapenemase gene detected by PCR resulted in susceptibility rates of 8.9%, 18.6%, and 18.6% to ertapenem, imipenem, and meropenem, respectively. By current breakpoints, <1% of these isolates were susceptible to ertapenem or imipenem and 2.6% to meropenem. Conclusion: Clinicians and epidemiologists should be aware that use of outdated MIC breakpoints for Enterobacteriaceae remains common and can result in reports of false susceptibility to carbapenems and missed identification of carbapenemase producers. This misclassification could have consequences for patient care and infection control efforts to address carbapenemase-producing Enterobacteriaceae.
Assuntos
Antibacterianos/farmacologia , Enterobacteriáceas Resistentes a Carbapenêmicos/isolamento & purificação , Carbapenêmicos/farmacologia , Infecções por Enterobacteriaceae/diagnóstico , Testes de Sensibilidade Microbiana/normas , Proteínas de Bactérias/genética , California , Enterobacteriáceas Resistentes a Carbapenêmicos/genética , Estudos Transversais , Humanos , Reação em Cadeia da Polimerase , Inquéritos e Questionários , Centros de Atenção Terciária/estatística & dados numéricos , beta-Lactamases/genéticaRESUMO
Antimicrobial resistance is the most pressing medical challenge of the past decade. At the front line are clinical laboratories, which are responsible for accurately reporting antimicrobial susceptibility test (AST) results to clinicians and public health authorities. The ability of the laboratory to detect resistance has been hampered by several factors. In 2016, the 21st Century Cures Act was signed into law, marking an important step toward resolving many regulatory dilemmas that hampered development and updates to commercial AST systems (cASTs). We describe the pathway and history of U.S. regulation of cASTs and outline both the rewards and unmet needs possible from the 21st Century Cures Act.
Assuntos
Antibacterianos/uso terapêutico , Testes Diagnósticos de Rotina/métodos , Política de Saúde/história , Política de Saúde/legislação & jurisprudência , Testes de Sensibilidade Microbiana/métodos , Testes Diagnósticos de Rotina/normas , História do Século XXI , Humanos , Testes de Sensibilidade Microbiana/normas , Estados UnidosRESUMO
The performance characteristics of the ceftolozane-tazobactam (C-T) Etest (bioMérieux, Marcy l'Etoile, France), MIC test strips (MTS; Liofilchem, Italy), and disk diffusion (Hardy, Santa Ana, CA) were evaluated for a collection of 308 beta-lactam-resistant isolates of Pseudomonas aeruginosa recovered from three institutions in Los Angeles, CA. Reference testing was performed by the reference broth microdilution (rBMD) method. MIC and disk results were interpreted using Clinical and Laboratory Standards Institute breakpoints. Overall, 72.5% of the isolates were susceptible to C-T by rBMD. Etest and disk diffusion demonstrated acceptable performance, whereas MTS yielded a greater than acceptable percentage of minor errors. Categorical agreement was 96.8% for Etest, 87.0% for MTS, and 92.9% for disk diffusion. No very major errors were observed by any test, and no major errors (ME) were observed by Etest or disk diffusion. Two ME (0.9% of susceptible isolates) were observed by MTS. The incidence of minor errors was 3.2%, 12.3%, and 7.1% for Etest, MTS, and disk diffusion, respectively. Essential agreement (EA) for Etest was excellent, at 97.7%, whereas the MICs obtained by MTS tended to be 1 to 2 dilutions higher than those obtained by rBMD, with an EA of 87.0%.
Assuntos
Antibacterianos/farmacologia , Técnicas Bacteriológicas/normas , Cefalosporinas/farmacologia , Testes de Sensibilidade Microbiana/normas , Pseudomonas aeruginosa/efeitos dos fármacos , Tazobactam/farmacologia , Resistência beta-Lactâmica/efeitos dos fármacos , Humanos , Técnicas de Diluição do Indicador/normas , Testes de Sensibilidade Microbiana/instrumentação , Pseudomonas aeruginosa/isolamento & purificaçãoRESUMO
Effective evaluations of antimicrobial susceptibility tests (ASTs) require robust study design. The Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing has recognized that many published studies reporting the performance of commercial ASTs (cASTs) suffer from major design and/or analysis flaws, rendering the results difficult or impossible to interpret. This minireview outlines the current consensus of the Methods Development and Standardization Working Group of the CLSI Subcommittee on Antimicrobial Susceptibility Testing regarding best practices for systematic evaluation of the performance of an AST, including the analysis and presentation of essential data intended for publication.
Assuntos
Técnicas de Laboratório Clínico/métodos , Técnicas de Laboratório Clínico/normas , Testes de Sensibilidade Microbiana/métodos , Testes de Sensibilidade Microbiana/normas , HumanosRESUMO
Ceftolozane-tazobactam (C/T) and ceftazidime-avibactam (CZA) MICs were evaluated for a collection of 309 beta-lactam-resistant isolates of Pseudomonas aeruginosa recovered from three institutions in the area of Los Angeles, CA. Overall, 12.0% of isolates were susceptible to imipenem, 15.9% were susceptible to meropenem, 20.7% were susceptible to piperacillin-tazobactam, 24.6% were susceptible to ceftazidime, 25.9% were susceptible to cefepime, 72.5% were susceptible to C/T, and 61.8% were susceptible to CZA. Among C/T-resistant isolates, 9.1% were CZA susceptible, whereas 36.4% of CZA-resistant isolates were susceptible to C/T.
Assuntos
Antibacterianos/farmacologia , Compostos Azabicíclicos/farmacologia , Ceftazidima/farmacologia , Cefalosporinas/farmacologia , Ácido Penicilânico/análogos & derivados , Pseudomonas aeruginosa/efeitos dos fármacos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Cefepima , Combinação de Medicamentos , Expressão Gênica , Humanos , Los Angeles , Meropeném , Testes de Sensibilidade Microbiana , Ácido Penicilânico/farmacologia , Piperacilina/farmacologia , Combinação Piperacilina e Tazobactam , Infecções por Pseudomonas/tratamento farmacológico , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/isolamento & purificação , Tazobactam , Tienamicinas/farmacologia , beta-Lactamases/metabolismoRESUMO
Carbapenemase-producing Enterobacteriaceae (CPE) are a significant threat to public health. In 2015, CDC revised the surveillance definition for CPE to include all Enterobacteriaceae resistant to any carbapenem tested. However, this definition is associated with poor specificity. We evaluated the performance of this definition, compared to carbapenemase PCR, for a collection of 125 Enterobacteriaceae We also investigated the impact of ancillary testing for carbapenemase of isolates that met the CDC CPE surveillance definition. The two ancillary tests evaluated were the Xpert Carba-R assay, a molecular test, and the carbapenem inactivation method (CIM). Two variables were evaluated for the CIM: suspension of organisms in double-distilled water (ddH2O) versus tryptic soy broth (TSB) to incubate disks, and incubation of plates for 6 h versus 18 to 20 h. The sensitivity and specificity of the Carba-R assay were 100% compared to the results of in-house PCR. The sensitivities of the CIM performed with TSB were 94.6% when read at 6 h and 97.7% when read at 18 to 20 h; the sensitivities with ddH2O were 88.0% when read at 6 h and 93.0% when incubated for 18 to 20 h. The specificity was 100% for all variables tested. Without ancillary testing, the sensitivity of the CDC definition was 98.9% for CPE, and the specificity was 6.1%. Testing isolates that screened positive by the CDC definition with the Xpert Carba-R did not change the sensitivity, and it improved the specificity to 100%. Similarly, the use of the CIM (TSB and 18 to 20 h of incubation) to confirm screen-positive isolates resulted in a sensitivity of 95.6% and specificity of 100%.
Assuntos
Proteínas de Bactérias/análise , Proteínas de Bactérias/genética , Técnicas Bacteriológicas/métodos , Enterobacteriáceas Resistentes a Carbapenêmicos/isolamento & purificação , beta-Lactamases/análise , beta-Lactamases/genética , Humanos , Sensibilidade e EspecificidadeRESUMO
The performances of Vitek 2 AST-GN69 and AST-XN06 cards were compared to Clinical and Laboratory Standards Institute (CLSI) reference broth microdilution (BMD) for 99 isolates of Pseudomonas aeruginosa, 26 Acinetobacter baumannii isolates, and 11 Stenotrophomonas maltophilia isolates. In total, 15 antimicrobials were evaluated, with 11 for P. aeruginosa, 14 for A. baumannii, and 2 for S. maltophilia Categorical agreement (CA) was assessed using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. The essential agreement values for P. aeruginosa, A. baumannii, and S. maltophilia were 99.5%, 99.2%, and 100%, respectively. The CA values for P. aeruginosa, A. baumannii, and S. maltophilia were 94.1%, 92.7%, and 95.5%, respectively, by the Vitek 2 breakpoints, and 93.4%, 92.3%, and 95.5%, respectively, by the CLSI breakpoints. Overall, the Vitek 2 performance was comparable to that of BMD using both Vitek 2 breakpoints and 2016 CLSI M100S 26th edition breakpoints. Improved performance was noted for the reformulated piperacillin-tazobactam and imipenem found on the AST-GN69 card, with no very major or major errors noted when using the CLSI breakpoints.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Pseudomonas aeruginosa/efeitos dos fármacos , Stenotrophomonas maltophilia/efeitos dos fármacos , HumanosRESUMO
Phenotypic variants of Staphylococcus aureus that display small colonies, reduced pigmentation, and decreased hemolysis and/or coagulase activity are periodically isolated by the clinical laboratory. Antimicrobial susceptibility testing (AST) of these isolates is complicated, because many do not grow on routine AST media, including Mueller-Hinton agar (MHA) and cation-adjusted Mueller-Hinton broth. This multicenter study evaluated cefoxitin disk diffusion for 37 atypical S. aureus isolates (156 readings) with MHA supplemented with 5% sheep's blood (BMHA), using mecA PCR as the reference standard. The correlation of two commercial PBP2a assays with mecA PCR was also assessed. Ten isolates were negative and 27 positive for mecA No major errors for cefoxitin were observed, but 19.5% very major errors (VMEs) were observed at 24 h of incubation, and 17.2% VMEs were observed at 48 h. The proportions of VMEs ranged from 14.7 to 23.0% at 24 h, and from 13.3 to 17.6% at 48 h, across three testing laboratories. PBP2a tests were performed from growth on BMHA and blood agar plates (BAP), with and without cefoxitin disk induction. The Alere PBP2a SA culture colony test sensitivities for mecA were 90.0% with uninduced growth and 97.4% with induced growth from BMHA. On BAP, sensitivity was 96.0% with induced growth. The sensitivities of the Oxoid PBP2' latex agglutination test were 85.7% with uninduced growth and 93.9% with induced growth from BMHA and 95.9% with induced growth on BAP. On the basis of these data, we recommend that laboratories perform only mecA PCR and/or PBP2a tests when requested to perform AST on atypical isolates of S. aureus.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/análise , Cefoxitina/farmacologia , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão/métodos , Oxacilina/farmacologia , Proteínas de Ligação às Penicilinas/análise , Staphylococcus aureus/efeitos dos fármacos , Resistência beta-Lactâmica , Meios de Cultura/química , Sensibilidade e Especificidade , Staphylococcus aureus/química , Staphylococcus aureus/crescimento & desenvolvimentoRESUMO
The Etest on chocolate Mueller-Hinton agar was compared to broth microdilution (BMD) for 125 isolates of nutritionally variant streptococci. Vancomycin Etests yielded 31.1% essential agreement (EA) and 20.0% categorical agreement (CA). Penicillin Etests yielded 86.0% EA and 85.6% CA, whereas ceftriaxone Etests yielded 73.6% EA and 68.0% CA.
Assuntos
Abiotrophia/efeitos dos fármacos , Antibacterianos/farmacologia , Carnobacteriaceae/efeitos dos fármacos , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão/métodos , Meios de Cultura/química , HumanosRESUMO
MIC results for 115 Staphylococcus intermedius group isolates are presented. Of these, 33% were methicillin resistant, among which 51.4% were susceptible to doxycycline, 29.7% to clindamycin, and 21.6% to trimethoprim-sulfamethoxazole. All of the isolates were susceptible to ceftaroline, daptomycin, linezolid, nitrofurantoin, quinupristin-dalfopristin, rifampin, tigecycline, and vancomycin. Of all the isolates, 82.6%, 67.8%, and 23.5% were susceptible to ciprofloxacin, erythromycin, and penicillin, respectively. No isolates harbored mupA or qacA/B genes, which suggested a lack of resistance to mupirocin or chlorhexidine.
Assuntos
Antibacterianos/farmacologia , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/veterinária , Staphylococcus intermedius/efeitos dos fármacos , Animais , Humanos , Testes de Sensibilidade Microbiana , Staphylococcus intermedius/isolamento & purificaçãoRESUMO
Rapid antimicrobial susceptibility testing (AST) would decrease misuse and overuse of antibiotics. The "holy grail" of AST is a phenotype-based test that can be performed within a doctor visit. Such a test requires the ability to determine a pathogen's susceptibility after only a short antibiotic exposure. Herein, digital PCR (dPCR) was employed to test whether measuring DNA replication of the target pathogen through digital single-molecule counting would shorten the required time of antibiotic exposure. Partitioning bacterial chromosomal DNA into many small volumes during dPCR enabled AST results after short exposure times by 1)â precise quantification and 2)â a measurement of how antibiotics affect the states of macromolecular assembly of bacterial chromosomes. This digital AST (dAST) determined susceptibility of clinical isolates from urinary tract infections (UTIs) after 15â min of exposure for all four antibiotic classes relevant to UTIs. This work lays the foundation to develop a rapid, point-of-care AST and strengthen global antibiotic stewardship.
Assuntos
Antibacterianos/farmacologia , Segregação de Cromossomos/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , DNA Bacteriano/efeitos dos fármacos , Reação em Cadeia da Polimerase , DNA Bacteriano/genéticaRESUMO
The rapid global spread of carbapenem-resistant Enterobacteriaceae (CRE) poses an urgent threat to public health. More than 250 class D ß-lactamases (OXAs) have been described in recent years, with variations in hydrolytic activity for ß-lactams. The plasmid-borne OXA-48 ß-lactamase and its variants are identified only sporadically in the United States but are common in Europe. Recognition of these OXA-48-like carbapenemases is vital in order to control their dissemination. We developed a real-time PCR assay based on high-resolution melt analysis, using bla OXA-48-like-specific primers coupled with an unlabeled 3'-phosphorylated oligonucleotide probe (LunaProbe) homologous to OXA-48-like carbapenemase genes. The assay was validated using genomic DNA from 48 clinical isolates carrying a variety of carbapenemase genes, including bla KPC, bla SME, bla IMP, bla NDM-1, bla VIM, bla OXA-48, bla OXA-162, bla OXA-181, bla OXA-204, bla OXA-244, bla OXA-245, and bla OXA-232. Our assay identified the presence of bla OXA-48-like ß-lactamase genes and clearly distinguished between bla OXA-48 and its variants in control strains, including between bla OXA-181 and bla OXA-232, which differ by only a single base pair in the assay target region. This approach has potential for use in epidemiological investigations and continuous surveillance to help control the spread of CRE strains producing OXA-48-like enzymes.