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4.
Clin Infect Dis ; 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32060524
5.
Clin Infect Dis ; 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-32052041

RESUMO

Recent data on polymyxin pharmacokinetics (PK), pharmacodynamics (PD), toxicity and clinical outcomes suggest these agents have limited clinical utility. PK-PD data show a steady state concentration of 2 ug/mL is required for killing bacteria with colistin minimum inhibitory concentrations (MICs) of 2 ug/mL. Less than 50% of patients with normal renal function achieve this exposure and it is associated with high risk of nephrotoxicity. This exposure does not achieve bacterial stasis in pneumonia models. Randomized and observational studies consistently demonstrate increased mortality for polymyxins compared to alternative agents. CLSI and EUCAST are two global organizations that establish interpretive criteria for in vitro susceptibility data. CLSI has recently taken the step to eliminate the "susceptible" interpretive category for the polymyxins, whereas EUCAST maintains this interpretive category. This viewpoint describes the opinions of the two organizations and the data that were used to inform their perspectives.

6.
Clin Infect Dis ; 70(6): 1240-1246, 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-31504338

RESUMO

Daptomycin is one of the few treatment options for infections caused by enterococci that are resistant to ampicillin and vancomycin, such as vancomycin-resistant Enterococcus faecium. The emergence and clinical significance of daptomycin-resistant enterococci and evolving microbiologic, pharmacokinetic-pharmacodynamic, and clinical data indicated that the pre-2019 Clinical and Laboratory Standards Institute (CLSI) susceptible-only breakpoint of ≤4 µg/mL for daptomycin and enterococci was no longer appropriate. After analyzing data that are outlined in this article, the CLSI Subcommittee on Antimicrobial Susceptibility Testing established new breakpoints for daptomycin and enterococci. For E. faecium, a susceptible dose-dependent (SDD) breakpoint of ≤4 µg/mL was established based on an increased dosage of 8-12 mg/kg/day (≥8 µg/mL-resistant). CLSI suggests infectious diseases consultation to guide daptomycin use for the SDD category. For Enterococcus faecalis and other enterococcal species, revised breakpoints of ≤2 µg/mL-susceptible, 4 µg/mL-intermediate, and ≥8 µg/mL-resistant were established based on a standard dosage of 6 mg/kg/day.

7.
J Clin Microbiol ; 58(2)2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31748324

RESUMO

Despite the increasing reliance on polymyxin antibiotics (polymyxin B and colistin) for treatment of multidrug-resistant Gram-negative infections, many clinical laboratories are unable to perform susceptibility testing due to the lack of accurate and reliable methods. Although gradient agar diffusion is commonly performed for other antimicrobials, its use for polymyxins is discouraged due to poor performance characteristics. Performing gradient agar diffusion with calcium enhancement of susceptibility testing media has been shown to improve the identification of polymyxin-resistant isolates with plasmid-mediated resistance (mcr-1). We therefore sought to evaluate the broad clinical applicability of this approach for colistin susceptibility testing by assessing a large and diverse collection of resistant and susceptible patient isolates collected from multiple U.S. medical centers. Among 217 isolates, the overall categorical and essential agreement for calcium-enhanced gradient agar diffusion were 73.7% and 65.5%, respectively, compared to the results for reference broth microdilution. Performance varied significantly by organism group, with agreement being highest for Enterobacterales and lowest for Pseudomonas aeruginosa Nevertheless, even for Enterobacterales, there was a high rate of very major errors (9.2%). Performance was similarly poor for calcium-enhanced broth microdilution. While calcium enhancement did allow for more accurate categorization of mcr-1-resistant isolates, there were unacceptably high rates of errors for both susceptible and non-mcr-1-resistant isolates, raising serious doubts about the suitability of these calcium-enhanced methods for routine colistin susceptibility testing in clinical laboratories.

8.
J Clin Microbiol ; 57(11)2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31511331

RESUMO

Susceptibility testing of the polymyxins (colistin and polymyxin B) is challenging for clinical laboratories. The Clinical and Laboratory Standards Institute (CLSI) Antimicrobial Susceptibility Testing Subcommittee evaluated two methods to enable accurate testing of these agents. These methods were a colistin broth disk elution (CBDE) and a colistin agar test (CAT), the latter of which was evaluated using two inoculum volumes, 1 µl (CAT-1) and 10 µl (CAT-10). The methods were evaluated using a collection of 270 isolates of Enterobacterales, 122 Pseudomonas aeruginosa isolates, and 106 Acinetobacter spp. isolates. Overall, 94.4% of CBDE results were in essential agreement and 97.9% in categorical agreement (CA) with reference broth microdilution MICs. Nine very major errors (VME; 3.2%) and 3 major errors (ME; 0.9%) were observed. With the CBDE, 98.6% CA was observed for Enterobacterales (2.5% VME, 0% ME), 99.3% CA was observed for P. aeruginosa (0% VME, 0.7% ME), and 93.1% CA was observed for Acinetobacter spp. (5.6% VME, 3.3% ME). Overall, CA was 94.9% with 6.8% VME using CAT-1 and improved to 98.3% with 3.9% VME using CAT-10. No ME were observed using either CAT-1 or CAT-10. Using the CAT-1/CAT-10, the CA observed was 99.4%/99.7% for Enterobacterales (1%/0.5% VME), 98.7%/100% for P. aeruginosa (8.3%/0% VME), and 88.5%/92.3% for Acinetobacter spp. (21.4%/14.3% VME). Based on these data, the CLSI antimicrobial susceptibility testing (AST) subcommittee endorsed the CBDE and CAT-10 methods for colistin testing of Enterobacterales and P. aeruginosa.

10.
N Engl J Med ; 380(24): 2327-2340, 2019 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-31189036

RESUMO

BACKGROUND: Metagenomic next-generation sequencing (NGS) of cerebrospinal fluid (CSF) has the potential to identify a broad range of pathogens in a single test. METHODS: In a 1-year, multicenter, prospective study, we investigated the usefulness of metagenomic NGS of CSF for the diagnosis of infectious meningitis and encephalitis in hospitalized patients. All positive tests for pathogens on metagenomic NGS were confirmed by orthogonal laboratory testing. Physician feedback was elicited by teleconferences with a clinical microbial sequencing board and by surveys. Clinical effect was evaluated by retrospective chart review. RESULTS: We enrolled 204 pediatric and adult patients at eight hospitals. Patients were severely ill: 48.5% had been admitted to the intensive care unit, and the 30-day mortality among all study patients was 11.3%. A total of 58 infections of the nervous system were diagnosed in 57 patients (27.9%). Among these 58 infections, metagenomic NGS identified 13 (22%) that were not identified by clinical testing at the source hospital. Among the remaining 45 infections (78%), metagenomic NGS made concurrent diagnoses in 19. Of the 26 infections not identified by metagenomic NGS, 11 were diagnosed by serologic testing only, 7 were diagnosed from tissue samples other than CSF, and 8 were negative on metagenomic NGS owing to low titers of pathogens in CSF. A total of 8 of 13 diagnoses made solely by metagenomic NGS had a likely clinical effect, with 7 of 13 guiding treatment. CONCLUSIONS: Routine microbiologic testing is often insufficient to detect all neuroinvasive pathogens. In this study, metagenomic NGS of CSF obtained from patients with meningitis or encephalitis improved diagnosis of neurologic infections and provided actionable information in some cases. (Funded by the National Institutes of Health and others; PDAID ClinicalTrials.gov number, NCT02910037.).


Assuntos
Líquido Cefalorraquidiano/microbiologia , Encefalite/microbiologia , Genoma Microbiano , Meningite/microbiologia , Metagenômica , Adolescente , Adulto , Líquido Cefalorraquidiano/virologia , Criança , Pré-Escolar , Encefalite/diagnóstico , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Infecções/diagnóstico , Tempo de Internação , Masculino , Meningite/diagnóstico , Meningoencefalite/diagnóstico , Meningoencefalite/microbiologia , Pessoa de Meia-Idade , Mielite/diagnóstico , Mielite/microbiologia , Estudos Prospectivos , Análise de Sequência de DNA , Análise de Sequência de RNA , Adulto Jovem
11.
Clin Microbiol Rev ; 32(3)2019 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-31142497

RESUMO

The evidence base for the optimal laboratory diagnosis of Clostridioides (Clostridium) difficile in adults is currently unresolved due to the uncertain performance characteristics and various combinations of tests. This systematic review evaluates the diagnostic accuracy of laboratory testing algorithms that include nucleic acid amplification tests (NAATs) to detect the presence of C. difficile The systematic review and meta-analysis included eligible studies (those that had PICO [population, intervention, comparison, outcome] elements) that assessed the diagnostic accuracy of NAAT alone or following glutamate dehydrogenase (GDH) enzyme immunoassays (EIAs) or GDH EIAs plus C. difficile toxin EIAs (toxin). The diagnostic yield of NAAT for repeat testing after an initial negative result was also assessed. Two hundred thirty-eight studies met inclusion criteria. Seventy-two of these studies had sufficient data for meta-analysis. The strength of evidence ranged from high to insufficient. The uses of NAAT only, GDH-positive EIA followed by NAAT, and GDH-positive/toxin-negative EIA followed by NAAT are all recommended as American Society for Microbiology (ASM) best practices for the detection of the C. difficile toxin gene or organism. Meta-analysis of published evidence supports the use of testing algorithms that use NAAT alone or in combination with GDH or GDH plus toxin EIA to detect the presence of C. difficile in adults. There is insufficient evidence to recommend against repeat testing of the sample using NAAT after an initial negative result due to a lack of evidence of harm (i.e., financial, length of stay, or delay of treatment) as specified by the Laboratory Medicine Best Practices (LMBP) systematic review method in making such an assessment. Findings from this systematic review provide clarity to diagnostic testing strategies and highlight gaps, such as low numbers of GDH/toxin/PCR studies, in existing evidence on diagnostic performance, which can be used to guide future clinical research studies.


Assuntos
Algoritmos , Infecções por Clostridium/diagnóstico , Técnicas de Amplificação de Ácido Nucleico/normas , Benchmarking , Infecções por Clostridium/microbiologia , Clostridium difficile/genética , Humanos
12.
J Clin Microbiol ; 57(7)2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31092593

RESUMO

In 2019, the Clinical and Laboratory Standards Institute revised the daptomycin breakpoints for Enterococcus spp. twice in rapid succession. Analyses leading to these revisions included review of testing issues, murine and human in vivo pharmacodynamics, safety of off-label doses, and treatment outcomes. The data review brought up a dilemma that is encountered with increasing frequency: a breakpoint supported by pharmacokinetic/pharmacodynamic modeling that bisected the wild-type Enterococcus faecium MIC distribution. In such instances, not only does the probability of pharmacokinetic/pharmacodynamic targets need to be taken into account but also the probability that the laboratory can generate an accurate MIC that is reproducible within one interpretive category.

13.
J Clin Microbiol ; 57(7)2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30995992

RESUMO

The Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing agree that carbapenemase testing is not necessary for clinical care, provided that the laboratory is up to date with current breakpoints. Nonetheless, publication on the development and modification of carbapenemase tests continues, as is the case in this issue of the Journal of Clinical Microbiology (R. W. Beresford and M. Maley, J Clin Microbiol 57:e01852-18, 2019, https://doi.org/10.1128/JCM.01852-18). This commentary explores modifications to the carbapenem inactivation method-but is this the right focus for clinical laboratories?


Assuntos
Enterobacteriáceas Resistentes a Carbapenêmicos , Proteínas de Bactérias , Carbapenêmicos , beta-Lactamases
15.
J Clin Microbiol ; 57(6)2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30971460

RESUMO

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.

16.
Diagn Microbiol Infect Dis ; 94(3): 213-217, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30723007

RESUMO

There are no commercially available Food and Drug Administration-cleared rapid tests for Neisseria gonorrhoeae antimicrobial susceptibility testing. This study evaluated the performance of a laboratory-developed real-time polymerase chain reaction assay for genotyping the gyrA gene to determine antimicrobial susceptibility to ciprofloxacin. Validation and clinical performance of the gyrA assay were evaluated across 3 geographic locations (Los Angeles, San Francisco, Philadelphia). Following validation, clinical specimens were collected in Aptima Combo2® CT/NG transport medium from asymptomatic persons who tested positive for Neisseria gonorrhoeae and evaluated for assay percent reportable (i.e., proportion of N. gonorrhoeae-positive specimens that yielded a gyrA genotype). The percentage of gyrA genotyping results differed by laboratory and specimen type. The proportion of specimens that were reportable was best for urine/genital specimens (genotyped = 76.4% (95% confidence interval, 69.9-82%)) followed by rectal (genotyped = 67.2% (95% confidence interval, 63.4-70.6%)) and then pharyngeal specimens (genotyped = 36.1%, (95% confidence interval, 31.9-40.5%)). Overall, asymptomatic patients with N. gonorrhoeae yielded an interpretable genotype 57.2% (784/1370) of the time, of which 480 were wild-type gyrA, resulting in 61% (480/784) being potentially treatable with ciprofloxacin.


Assuntos
Antibacterianos/farmacologia , Ciprofloxacino/farmacologia , Farmacorresistência Bacteriana , Gonorreia/microbiologia , Testes de Sensibilidade Microbiana/métodos , Neisseria gonorrhoeae/efeitos dos fármacos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Adolescente , Adulto , Idoso , DNA Girase/genética , Genótipo , Técnicas de Genotipagem/métodos , Humanos , Los Angeles , Pessoa de Meia-Idade , Neisseria gonorrhoeae/genética , Philadelphia , São Francisco , Fatores de Tempo , Adulto Jovem
17.
J Antimicrob Chemother ; 74(5): 1241-1243, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30753572

RESUMO

OBJECTIVES: Ceftazidime/avibactam resistance due to mutation in the omega loop of KPC-2 has been documented in vitro and in vivo. This study evaluated the mechanism of ceftazidime/avibactam resistance in a KPC-2-expressing Klebsiella pneumoniae isolated from a patient following ceftazidime/avibactam combination therapy with gentamicin for the treatment of ventilator-associated pneumonia. METHODS: Ceftazidime/avibactam-susceptible and -resistant isolates of K. pneumoniae were evaluated by broth microdilution and WGS. The KPC-2 gene was cloned from the ceftazidime/avibactam-resistant isolate and evaluated for susceptibility to ceftazidime/avibactam, in an Escherichia coli background. RESULTS: A single L169P mutation was identified in the KPC-2 gene between the ceftazidime/avibactam-resistant and -susceptible isolates. The novel KPC-2 allele, designated KPC-35, was shown to confer reduced susceptibility to ceftazidime/avibactam and increased susceptibility to carbapenems, as compared with KPC-2. CONCLUSIONS: A novel L169P mutation was identified in KPC-2 and was shown through cloning experiments to confer reduced susceptibility to ceftazidime/avibactam.

18.
J Clin Microbiol ; 57(3)2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30651391

RESUMO

The Accelerate Pheno system (AXDX) is a rapid phenotypic bacterial identification and susceptibility testing system which is approved for use with positive blood cultures. Acinetobacter baumannii is a nosocomial pathogen for which the limited treatment options include minocycline in the case of multidrug resistance. Here, we studied the performance of A. baumannii identification and minocycline susceptibility testing by AXDX using 101 contemporary Acinetobacter sp. clinical isolates. Overall, the sensitivity for A. baumannii and A. baumannii complex identification was 100% (73/73) and 97.6% (82/84), respectively. Specificity for A. baumannii complex identification was 86.6% (13/15). The essential agreement of minocycline susceptibility results (±1 log2 MIC agreement) of AXDX MICs with reference broth microdilution was 98.0% (96/98). There were no very major errors or major errors. Overall, 24.5% (24/98) of results yielded minor errors. AXDX reliably identified A. baumannii and predicted minocycline susceptibility results, which should help guide treatment choices in a timely manner for infections where options are limited.


Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/isolamento & purificação , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Testes de Sensibilidade Microbiana/normas , Minociclina/farmacologia , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/classificação , Hemocultura , Farmacorresistência Bacteriana , Humanos , Hibridização in Situ Fluorescente , Sensibilidade e Especificidade
19.
Clin Infect Dis ; 68(12): 2045-2052, 2019 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-30256922

RESUMO

BACKGROUND: In Pseudomonas aeruginosa, fluoroquinolone exposure promotes resistance to carbapenems through upregulation of efflux pumps and transcriptional downregulation of the porin OprD. Evidence of this effect among hematologic malignancy (HM) patients or hematopoietic cell transplant (HCT) recipients receiving fluoroquinolone prophylaxis for neutropenia is lacking. METHODS: We retrospectively evaluated episodes of P. aeruginosa bloodstream infections in HM patients or HCT recipients over a 7-year period at our institution. We determined the association of fluoroquinolone prophylaxis at the time of infection with meropenem susceptibility of P. aeruginosa breakthrough isolates and risk factors for meropenem nonsusceptibility. Whole-genome sequencing (WGS) and phenotypic assessments of meropenem efflux pump activity were performed on select isolates to determine the mechanisms of meropenem resistance. RESULTS: We analyzed 55 episodes of P. aeruginosa bacteremia among 51 patients. Breakthrough bacteremia while on fluoroquinolone prophylaxis was associated with nonsusceptibility to meropenem, but not to antipseudomonal ß-lactams or aminoglycosides. The receipt of fluoroquinolone prophylaxis was independently predictive of bacteremia with a meropenem-nonsusceptible isolate. All meropenem-nonsusceptible isolates analyzed by WGS contained oprD inactivating mutations, and all meropenem-nonsusceptible isolates tested demonstrated reductions in the meropenem minimum inhibitory concentration in the presence of an efflux pump inhibitor. A phylogenetic analysis based on WGS revealed several clusters of closely related isolates from different patients. CONCLUSIONS: Fluoroquinolone prophylaxis in HM patients and HCT recipients is associated with breakthrough bacteremia with meropenem-nonsusceptible P. aeruginosa strains, likely due to both mutations increasing efflux pump activity and the epidemiology of P. aeruginosa bloodstream infections in our patient population.

20.
Sex Transm Dis ; 46(1): e3-e4, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30216232

RESUMO

Gyrase A genotyping reliably predicts Neisseria gonorrhoeae susceptibility to ciprofloxacin. It is unknown whether concurrent infections at different anatomic sites harbor different susceptibility profiles. We found a 3.2% frequency of discordant gyrase A genotypes among concurrent but anatomically separate N. gonorrhoeae infections diagnosed at 2 laboratories in Los Angeles.


Assuntos
DNA Girase/genética , Genótipo , Gonorreia/microbiologia , Neisseria gonorrhoeae/enzimologia , Neisseria gonorrhoeae/genética , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Ciprofloxacino/farmacologia , Farmacorresistência Bacteriana , Humanos , Los Angeles , Testes de Sensibilidade Microbiana , Neisseria gonorrhoeae/efeitos dos fármacos , Estudos Retrospectivos
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