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1.
J Clin Microbiol ; 58(6)2020 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-32161094

RESUMEN

Each year, there are an estimated 11 million visits to ambulatory care centers for pharyngitis in children between the ages of 3 and 18 years. While there are many causes of pediatric pharyngitis, group A streptococcal pharyngitis represents 15 to 30% of infections and is the only cause for which treatment is recommended. Unfortunately, clinical suspicion is insufficient for the accurate diagnosis of group A streptococcal pharyngitis, and laboratory testing for confirmation of Streptococcus pyogenes infection is required to prevent complications of infection. Traditionally, throat swabs are inoculated onto agar plates for isolation of the large-zone beta-hemolytic streptococcus. However, traditional culture methods present a potential delay in treatment due to turnaround times of 18 to 48 h. In order to improve turnaround times and enhance antimicrobial stewardship, multiple point-of-care assays have been developed. This review describes current point-of-care testing for group A streptococcal pharyngitis, including rapid antigen detection tests and more recent molecular methods. Additional attention is given to the diagnostic considerations when choosing a method for group A streptococcal point-of-care testing, implementation of molecular group A streptococcal testing, and the institutional cost of immunoassays compared to those of newer molecular methods.


Asunto(s)
Pediatría , Faringitis , Infecciones Estreptocócicas , Adolescente , Antígenos Bacterianos , Niño , Preescolar , Humanos , Técnicas de Diagnóstico Molecular , Faringitis/diagnóstico , Sistemas de Atención de Punto , Pruebas en el Punto de Atención , Infecciones Estreptocócicas/diagnóstico , Streptococcus pyogenes/genética
2.
Eur J Clin Microbiol Infect Dis ; 39(11): 2037-2044, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32577953

RESUMEN

Carbapenem-resistant Gram-negative bacilli are a major public health problem. Accurate and rapid detection of carbapenemase-producing organisms can facilitate appropriate infection prevention measures. The objective was to evaluate the performance of the RAPIDEC® CARBA NP assay (RAPIDEC), a screening assay that utilizes a pH indicator to detect carbapenem hydrolysis within 2 h. A multicenter study evaluated 306 clinical bacterial strains of Enterobacterales (n = 257) and Pseudomonas aeruginosa (n = 49). The RAPIDEC was compared to a composite reference standard-the Clinical Laboratory Standards Institute (CLSI) Carba NP assay, PCR for specific carbapenemase genes (blaKPC, blaNDM, blaOXA-48-like, blaVIM and blaIMP), and phenotypic carbapenem susceptibility testing. The assay was evaluated using two culture incubation times for the bacterial isolates: "routine"(cultures incubated 18-24 h) and "short" (cultures incubated 4-5 h). For the routine incubation, the overall percent agreement was 98.7% with a positive percent agreement (PPA) of 99.6% and a negative percent agreement (NPA) of 97.4%; there were five false positives and one false negative. For the short incubation, the overall percent agreement was 98.0% with a PPA of 98.5% and a NPA of 97.3%; there were five false positives and four false negatives. RAPIDEC results for the P. aeruginosa isolates were 100% concordant with the reference standard for both incubation times. The RAPIDEC assay is an accurate and rapid (≤ 2 h) assay for the detection of the most common carbapenemases in clinical isolates. Growth from a short incubation culture may be used to reliably detect carbapenemase production in clinical strains.


Asunto(s)
Proteínas Bacterianas/metabolismo , Enterobacteriaceae Resistentes a los Carbapenémicos/metabolismo , Pseudomonas aeruginosa/metabolismo , beta-Lactamasas/metabolismo , Programas de Optimización del Uso de los Antimicrobianos , Técnicas Bacteriológicas , Humanos , Sensibilidad y Especificidad , Estados Unidos
3.
Eur J Clin Microbiol Infect Dis ; 38(12): 2323-2330, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31446513

RESUMEN

Historically, vancomycin has been considered a primary therapeutic option for treating infections with Staphylococcus aureus, but isolates with reduced vancomycin susceptibility (SA-RVS) (MIC ≥ 4 µg/mL) have emerged. Telavancin, a semisynthetic lipoglycopeptide, is an alternative treatment option for S. aureus, but data examining telavancin activity against SA-RVS are limited. In the present study, we characterize 300 isolates of S. aureus isolates (50 vancomycin-susceptible (VSSA) isolates and 250 SA-RVS isolates) from a large tertiary care, academic medical center, 51.8% of which were methicillin resistant (MRSA). Sixteen (6.4%) SA-RVS isolates were non-susceptible to telavancin, whereas all VSSA isolates were susceptible. Additionally, 3.6% of SA-RVS isolates were non-susceptible to daptomycin, with three (1.2%) isolates testing non-susceptible to both telavancin and daptomycin. When tested against other classes of antimicrobials, there were no statistical differences in susceptibility of VSSA and SA-RVS isolates, except for the fluoroquinolones (ciprofloxacin and moxifloxacin). Molecular characterization of the isolates showed that SCCmec types II and IV together represented over half of the SA-RVS isolates; 12.0% of the VSSA isolates were SCCmec type II. Using RepPCR, we detected 16 distinct strain types in this isolate collection, and tst-1 (gene encoding the Staphylococcus toxic shock syndrome super-antigen) carriage was low (5.4%). Overall, we show that in addition to reduced vancomycin susceptibility, a small, but clinically significant, proportion of SA-RVS isolates also demonstrate reduced susceptibility to both telavancin and daptomycin.


Asunto(s)
Aminoglicósidos/farmacología , Antibacterianos/farmacología , Tolerancia a Medicamentos , Lipoglucopéptidos/farmacología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/aislamiento & purificación , Vancomicina/farmacología , Centros Médicos Académicos , Adulto , Anciano , Anciano de 80 o más Años , Proteínas Bacterianas/genética , Daptomicina/farmacología , Tolerancia a Medicamentos/genética , Femenino , Humanos , Masculino , Resistencia a la Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/clasificación , Staphylococcus aureus/genética , Centros de Atención Terciaria , Adulto Joven
4.
Eur J Clin Microbiol Infect Dis ; 37(12): 2405-2411, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30269180

RESUMEN

Total laboratory automation (TLA) has the potential to reduce specimen processing time, improve standardization of cultures, and decrease turnaround time (TAT). The objective of this study was to perform a detailed interrogation of the impact of TLA implementation in all aspects of the workflow for routine culture of urine specimens. Using a detailed motion capture study, the time required for major steps of processing and result reporting were prospectively assessed for urine samples prior to (n = 215) and after (n = 203) implementation of the BD Kiestra TLA system. Specimens were plated on all shifts, but cultures were read only during the day shift for both time periods. Significant increases were noted in the time from receipt to inoculation (23.0 min versus 32.0 min, p < 0.001) and total processing time (28.0 min versus 66.0 min, p < 0.0001) for urine specimens post-TLA. Rates of positive (18.6% versus 16.3%) and negative (71.2% versus 79.3%) urine cultures remained stable through the pre- and post-TLA time periods (p = 0.58). There were no changes in TAT for organism identification or susceptibility results. The time to final report was decreased from 43.8 h pre-TLA to 42.0 h post-TLA, which was attributed to significant decreases in TAT for negative cultures (42.0 h versus 37.5 h, p = 0.01). These findings demonstrate that changes in laboratory workflow are necessary to maximize efficiency of TLA and optimize TAT.


Asunto(s)
Automatización de Laboratorios , Técnicas Bacteriológicas/instrumentación , Manejo de Especímenes/instrumentación , Flujo de Trabajo , Técnicas Bacteriológicas/métodos , Humanos , Estudios de Tiempo y Movimiento , Orina/microbiología
5.
Artículo en Inglés | MEDLINE | ID: mdl-28848008

RESUMEN

Infections with Corynebacterium striatum have been described in the literature over the last 2 decades, with the majority being bacteremia, central line infections, and occasionally, endocarditis. In recent years, the frequency of C. striatum infections appears to be increasing; a factor likely contributing to this is the increased ease and accuracy of the identification of Corynebacterium spp., including C. striatum, from clinical cultures. The objective of this study was to retrospectively characterize C. striatum isolates recovered from specimens submitted as part of routine patient care at a 1,250-bed, tertiary-care academic medical center. Multiple strain types were recovered, as demonstrated by repetitive-sequence-based PCR. Most of the strains of C. striatum characterized were resistant to antimicrobials commonly used to treat Gram-positive organisms, such as penicillin, ceftriaxone, meropenem, clindamycin, and tetracycline. The MIC50 for ceftaroline was >32 µg/ml. Although there are no interpretive criteria for susceptibility with telavancin, it appeared to have potent in vitro efficacy against this species, with MIC50 and MIC90 values of 0.064 and 0.125 µg/ml, respectively. Finally, as previously reported in case studies, we demonstrated rapid in vitro development of daptomycin resistance in 100% of the isolates tested (n = 50), indicating that caution should be exhibited when using daptomycin for the treatment of C. striatum infections. C. striatum is an emerging, multidrug-resistant pathogen that can be associated with a variety of infection types.


Asunto(s)
Antibacterianos/farmacología , Infecciones por Corynebacterium/epidemiología , Corynebacterium/efectos de los fármacos , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Adulto , Anciano , Anciano de 80 o más Años , Aminoglicósidos/farmacología , Corynebacterium/clasificación , Corynebacterium/genética , Corynebacterium/aislamiento & purificación , Infecciones por Corynebacterium/tratamiento farmacológico , Infecciones por Corynebacterium/microbiología , Femenino , Humanos , Lipoglucopéptidos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Missouri/epidemiología , Tipificación Molecular , Estudios Retrospectivos
6.
Clin Chem ; 63(3): 723-730, 2017 03.
Artículo en Inglés | MEDLINE | ID: mdl-28073895

RESUMEN

BACKGROUND: Carbapenemase-producing gram-negative bacteria (CP-GNB) are an urgent and expanding public health threat. Rapid and accurate identification of these organisms facilitates infection prevention efforts in healthcare facilities. The objective of our study was to evaluate methods to detect and identify CP-GNB. METHODS: We examined 189 carbapenem-resistant GNB(CR-GNB), including Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii complex, using 3 different methods: 2 methods to screen isolates of GNB for carbapenemase production [the carbapenem inactivation method (CIM) and 2 chromogenic agars] and a molecular method (Cepheid GeneXpert Carba-R) to identify the mechanism of carbapenem resistance and the associated resistance genes (blaKPC, blaNDM, blaIMP, blaOXA-48-like, and blaVIM). RESULTS: The CIM was a simple and inexpensive phenotypic screen to differentiate between CR-GNB and CP-GNB, with improved analytical performance characteristics and inter-reader correlation compared to the modified Hodge test. Both chromogenic agars evaluated (HardyCHROM CRE and chromID CARBA) were able to support growth of most of the organisms tested, including isolates possessing the blaOXA-48-like gene. However, these media had a low analytical specificity for carbapenemase production, with breakthrough of CR-GNB that did not produce a carbapenemase. The Xpert Carba-R assay was rapid and easy to perform, and demonstrated 100% positive and negative agreement for characterization of genetic determinants of carbapenem resistance. CONCLUSIONS: Screening by CIM followed by the Xpert Carba-R PCR is an accurate method for detecting and characterizing CP-GNB, including Enterobacteriaceae, P. aeruginosa, and A. baumannii complex.


Asunto(s)
Acinetobacter baumannii/genética , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/genética , Farmacorresistencia Microbiana/genética , Enterobacteriaceae/genética , Pseudomonas aeruginosa/genética , beta-Lactamasas/biosíntesis , beta-Lactamasas/genética , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/enzimología , Proteínas Bacterianas/metabolismo , Carbapenémicos/farmacología , Farmacorresistencia Microbiana/efectos de los fármacos , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/enzimología , Genotipo , Fenotipo , Reacción en Cadena de la Polimerasa , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/enzimología , beta-Lactamasas/metabolismo
7.
J Clin Microbiol ; 54(8): 2068-73, 2016 08.
Artículo en Inglés | MEDLINE | ID: mdl-27225405

RESUMEN

Invasive fungal infections have a high rate of morbidity and mortality, and accurate identification is necessary to guide appropriate antifungal therapy. With the increasing incidence of invasive disease attributed to filamentous fungi, rapid and accurate species-level identification of these pathogens is necessary. Traditional methods for identification of filamentous fungi can be slow and may lack resolution. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid and accurate method for identification of bacteria and yeasts, but a paucity of data exists on the performance characteristics of this method for identification of filamentous fungi. The objective of our study was to evaluate the accuracy of the Vitek MS for mold identification. A total of 319 mold isolates representing 43 genera recovered from clinical specimens were evaluated. Of these isolates, 213 (66.8%) were correctly identified using the Vitek MS Knowledge Base, version 3.0 database. When a modified SARAMIS (Spectral Archive and Microbial Identification System) database was used to augment the version 3.0 Knowledge Base, 245 (76.8%) isolates were correctly identified. Unidentified isolates were subcultured for repeat testing; 71/319 (22.3%) remained unidentified. Of the unidentified isolates, 69 were not in the database. Only 3 (0.9%) isolates were misidentified by MALDI-TOF MS (including Aspergillus amoenus [n = 2] and Aspergillus calidoustus [n = 1]) although 10 (3.1%) of the original phenotypic identifications were not correct. In addition, this methodology was able to accurately identify 133/144 (93.6%) Aspergillus sp. isolates to the species level. MALDI-TOF MS has the potential to expedite mold identification, and misidentifications are rare.


Asunto(s)
Hongos/aislamiento & purificación , Técnicas Microbiológicas/métodos , Micosis/diagnóstico , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Errores Diagnósticos , Hongos/química , Humanos , Micosis/microbiología , Sensibilidad y Especificidad
8.
J Clin Microbiol ; 53(7): 2308-15, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25972426

RESUMEN

When mycobacteria are recovered in clinical specimens, timely species-level identification is required to establish the clinical significance of the isolate and facilitate optimization of antimicrobial therapy. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been reported to be a reliable and expedited method for identification of mycobacteria, although various specimen preparation techniques and databases for analysis are reported across studies. Here we compared two MALDI-TOF MS instrumentation platforms and three databases: Bruker Biotyper Real Time Classification 3.1 (Biotyper), Vitek MS Plus Saramis Premium (Saramis), and Vitek MS v3.0. We evaluated two sample preparation techniques and demonstrate that extraction methods are not interchangeable across different platforms or databases. Once testing parameters were established, a panel of 157 mycobacterial isolates (including 16 Mycobacterium tuberculosis isolates) was evaluated, demonstrating that with the appropriate specimen preparation, all three methods provide reliable identification for most species. Using a score cutoff value of ≥1.8, the Biotyper correctly identified 133 (84.7%) isolates with no misidentifications. Using a confidence value of ≥90%, Saramis correctly identified 134 (85.4%) isolates with one misidentification and Vitek MS v3.0 correctly identified 140 (89.2%) isolates with one misidentification. The levels of accuracy were not significantly different across the three platforms (P = 0.14). In addition, we show that Vitek MS v3.0 requires modestly fewer repeat analyses than the Biotyper and Saramis methods (P = 0.04), which may have implications for laboratory workflow.


Asunto(s)
Técnicas Bacteriológicas/métodos , Mycobacterium/clasificación , Mycobacterium/aislamiento & purificación , Manejo de Especímenes/métodos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Bases de Datos de Compuestos Químicos , Humanos , Mycobacterium/química , Infecciones por Mycobacterium/diagnóstico
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