RESUMEN
The use of molecular identification panels has advanced the diagnosis for blood stream infections with fast turnaround time and high accuracy. Yet, this technology cannot completely replace conventional blood culture and standardized antibiotic susceptibility testing (AST) given its limitations and occasional false results. Here we present two cases of bacteremia caused by Kluyvera. Its identification and antibiotic resistance were at least partially mispresented by blood culture molecular identification panels on ePlex, Verigene, and Biofire. The detection of CTX-M resistance marker did not align with the susceptibility to the third generation cephalosporins among a wide range of antibiotics for this organism. Conventional extended-spectrum beta-lactamase (ESBL) testing was used to confirm the absence of ESBL. Caution should be taken when managing cases with CTX-M or ESBL detection in blood culture caused by uncommon pathogens. Conventional culture with microbial identification and standardized AST should continue to be the gold standard for routine patient care. IMPORTANCE: This is the first report that highlights the limitations of blood culture molecular identification panels on identifying Kluyvera and its associated antibiotic resistance patterns. Both the false identification and overreporting of antibiotic resistance could mislead the treatment for bacteremia caused by this pathogen. Patient isolation could have been avoided due to the lack of extended-spectrum beta-lactamase (ESBL) activity of the organism. This report emphasizes the importance of confirming rapid identification and antibiotic resistance by molecular technologies with standardized methods. It also provides insight into the development of new diagnostic panels.
Asunto(s)
Antibacterianos , Bacteriemia , Cultivo de Sangre , Kluyvera , Pruebas de Sensibilidad Microbiana , beta-Lactamasas , Femenino , Humanos , Masculino , Antibacterianos/farmacología , Bacteriemia/microbiología , Bacteriemia/diagnóstico , Bacteriemia/tratamiento farmacológico , beta-Lactamasas/genética , Cultivo de Sangre/métodos , Cefalosporinas/farmacología , Cefalosporinas/uso terapéutico , Errores Diagnósticos , Farmacorresistencia Bacteriana/genética , Infecciones por Enterobacteriaceae/microbiología , Infecciones por Enterobacteriaceae/diagnóstico , Infecciones por Enterobacteriaceae/tratamiento farmacológico , Kluyvera/genética , Kluyvera/efectos de los fármacos , Kluyvera/aislamiento & purificación , Anciano de 80 o más AñosRESUMEN
Detection of Bordetella pertussis and Bordetella parapertussis using molecular methods is sensitive and specific with a short turnaround time compared to other diagnostic methods. In this multicenter study, we compared the performance of the Simplexa Bordetella Direct kit to those of other molecular assays in detecting and differentiating B. pertussis and B. parapertussis in nasopharyngeal swab specimens. The limits of detection (LODs) were 150 CFU/ml or 3 fg/µl of DNA for B. pertussis and 1,500 CFU/ml or 10 fg/µl of DNA for B. parapertussis A total of 1,103 fresh and residual frozen specimens from eight clinical sites were tested. Combining the data from individual clinical sites using different comparative assays, the overall positive percent agreement (PPA) and negative percent agreement (NPA) for B. pertussis were 98.7% and 97.3%, respectively. The overall PPA and NPA for B. parapertussis were 96.7% and 100%, respectively. For prospective fresh specimens, the overall PPA and NPA for both targets were 97.7% and 99.3%, respectively. For retrospective frozen specimens, the overall PPA and NPA for both targets were 92.6% and 93.2%, respectively. The percentage of invalid results was 1.0%. A cross-reactivity study using 74 non-Bordetella bacterial species and five yeast species revealed that the Simplexa Bordetella Direct kit was 100% specific. The hands-on time and assay run time of the Simplexa Bordetella Direct kit are favorable compared to those of other commercial and laboratory-developed tests. In summary, the Simplexa Bordetella Direct kit has a performance comparable to those of other molecular assays for the detection of B. pertussis and B. parapertussis.
Asunto(s)
Infecciones por Bordetella , Bordetella parapertussis , Bordetella , Tos Ferina , Bordetella/genética , Infecciones por Bordetella/diagnóstico , Bordetella parapertussis/genética , Bordetella pertussis/genética , Humanos , Nasofaringe , Estudios Prospectivos , Estudios Retrospectivos , Tos Ferina/diagnósticoRESUMEN
BACKGROUND: There is a growing understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease 2019 (COVID-19) in the general population. The unique immunology of pregnancy may result in variations from the reported course of disease. CASE: A 27-year-old primigravid woman presented with mild COVID-19 symptoms at 28 2/7 weeks of gestation, testing positive for SARS-CoV-2 infection by nasopharyngeal swab reverse transcription-polymerase chain reaction (RT-PCR). Antibody seroconversion was detected at 36 6/7 weeks of gestation. She presented for delivery at 38 1/7 weeks of gestation, and her SARS-CoV-2 RT-PCR test result was positive. Severe acute respiratory syndrome coronavirus 2 RNA remained detectable 34 days postpartum and 104 days from her initial positive test. CONCLUSION: Prolonged viral shedding of SARS-CoV RNA may occur in the pregnant patient. If prevalent, this complicates the interpretation of a positive SARS-CoV-2 RT-PCR test result in the asymptomatic gravid patient.
Asunto(s)
Anticuerpos Antivirales/sangre , Betacoronavirus , Técnicas de Laboratorio Clínico/métodos , Infecciones por Coronavirus , Pandemias , Neumonía Viral , Complicaciones Infecciosas del Embarazo , Seroconversión/fisiología , Esparcimiento de Virus/inmunología , Adulto , Betacoronavirus/inmunología , Betacoronavirus/aislamiento & purificación , COVID-19 , Prueba de COVID-19 , Infecciones por Coronavirus/diagnóstico , Infecciones por Coronavirus/inmunología , Femenino , Edad Gestacional , Humanos , Monitorización Inmunológica/métodos , Neumonía Viral/diagnóstico , Neumonía Viral/inmunología , Embarazo , Complicaciones Infecciosas del Embarazo/diagnóstico , Complicaciones Infecciosas del Embarazo/inmunología , SARS-CoV-2 , Factores de TiempoRESUMEN
Clostridioides difficile infection (CDI) is one of the most common health care-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We evaluated the clinical performance of ultrasensitive single-molecule counting technology for detection of C. difficile toxins A and B. Stool specimens from 298 patients with suspected CDI were tested with the nucleic acid amplification test (NAAT; BD MAX Cdiff assay or Xpert C. difficile assay) and Singulex Clarity C. diff toxins A/B assay. Specimens with discordant results were tested with the cell cytotoxicity neutralization assay (CCNA), and the results were correlated with disease severity and outcome. There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity- and 4 NAAT-/Clarity+ samples, there were 26 CCNA- and 4 CCNA- samples, respectively. CDI relapse was more common in NAAT+/toxin+ patients than in NAAT+/toxin- and NAAT-/toxin- patients. The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was more than three times more common in NAAT+/toxin- than in NAAT+/toxin+ patients. The Clarity assay was superior to NAATs for the diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and the presence of toxins was associated with negative patient outcomes.
Asunto(s)
Infecciones por Clostridium/diagnóstico , Enterotoxinas/aislamiento & purificación , Inmunoensayo/métodos , Imagen Individual de Molécula/métodos , Adulto , Anciano , Técnicas Bacteriológicas/métodos , Clostridioides difficile/química , Clostridioides difficile/genética , Infecciones por Clostridium/microbiología , Heces/química , Heces/microbiología , Femenino , Humanos , Masculino , Uso Excesivo de los Servicios de Salud , Persona de Mediana Edad , Técnicas de Amplificación de Ácido Nucleico , Sensibilidad y EspecificidadAsunto(s)
Reglas de Decisión Clínica , Infecciones por Clostridium/diagnóstico , Infección Hospitalaria/diagnóstico , Toma de Decisiones Asistida por Computador , Transmisión de Enfermedad Infecciosa/prevención & control , Educación Médica Continua/métodos , Control de Infecciones/métodos , Preescolar , Infecciones por Clostridium/prevención & control , Infección Hospitalaria/prevención & control , Humanos , Incidencia , Lactante , Recién Nacido , Estudios RetrospectivosAsunto(s)
Absceso Encefálico/diagnóstico por imagen , Lóbulo Frontal/diagnóstico por imagen , Huésped Inmunocomprometido , Anciano de 80 o más Años , Antiinfecciosos/uso terapéutico , Técnicas Bacteriológicas , Absceso Encefálico/tratamiento farmacológico , Absceso Encefálico/microbiología , Absceso Encefálico/patología , Lóbulo Frontal/patología , Humanos , Masculino , Prednisona/efectos adversosAsunto(s)
Antibacterianos/farmacología , Absceso Encefálico/diagnóstico , Absceso Encefálico/microbiología , Huésped Inmunocomprometido , Nocardiosis/diagnóstico , Nocardia/efectos de los fármacos , Nocardia/aislamiento & purificación , Prednisona/efectos adversos , Anciano de 80 o más Años , Antibacterianos/uso terapéutico , Técnicas Bacteriológicas , Absceso Encefálico/tratamiento farmacológico , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Nocardia/clasificación , Nocardiosis/tratamiento farmacológicoRESUMEN
Strongyloides stercoralis is an important human parasite, especially in rural areas and developing countries. Infected immunosuppressed patients are at risk for hyperinfection, with severe clinical consequences. Here we describe the incidental detection and diagnosis of an unexpected S. stercoralis infection by methods designed to detect fungal 28S ribosomal DNA.
Asunto(s)
Neoplasias Hematológicas/complicaciones , Strongyloides stercoralis/aislamiento & purificación , Estrongiloidiasis/diagnóstico , Estrongiloidiasis/patología , Animales , Análisis por Conglomerados , ADN de Helmintos/química , ADN de Helmintos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Humanos , Masculino , Microscopía , Persona de Mediana Edad , Filogenia , Reacción en Cadena de la Polimerasa , ARN Ribosómico 28S/genética , Análisis de Secuencia de ADN , Strongyloides stercoralis/genética , Estrongiloidiasis/parasitologíaRESUMEN
Serology remains critical for diagnosing hepatitis D virus (HDV) infection, which affects 15 to 20 million people worldwide, but the literature on characterizing commercial enzyme immunoassays (EIAs) dates back to 15 years ago. We evaluated 2 commercial EIAs currently available for detecting anti-HDV antibodies. The DiaSorin assay demonstrated 100% sensitivity and specificity. Using a modified cutoff value, the Cusabio assay demonstrated a sensitivity of 81.3% and specificity of 90.9%. Our data show that recently developed EIAs are reliable for anti-HDV antibody detection.
Asunto(s)
Anticuerpos Antihepatitis/sangre , Hepatitis D/diagnóstico , Virus de la Hepatitis Delta/inmunología , Técnicas para Inmunoenzimas/métodos , Humanos , Sensibilidad y Especificidad , Suero/inmunologíaAsunto(s)
Endocarditis/tratamiento farmacológico , Penicilinas/farmacología , Penicilinas/uso terapéutico , Infecciones Estreptocócicas/tratamiento farmacológico , Streptococcus/efectos de los fármacos , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Resultado del Tratamiento , Adulto JovenAsunto(s)
Infecciones por Corynebacterium/diagnóstico , Corynebacterium/aislamiento & purificación , Queratoconjuntivitis/diagnóstico , Adulto , Anciano de 80 o más Años , Infecciones por Corynebacterium/microbiología , Diagnóstico Diferencial , Técnicas de Diagnóstico Oftalmológico , Femenino , Humanos , Queratoconjuntivitis/microbiología , Masculino , Persona de Mediana Edad , WashingtónRESUMEN
OBJECTIVE: Regulatory T cells (Treg) play a critical role in the prevention of autoimmunity, and the suppressive activity of these cells is impaired in rheumatoid arthritis (RA). The aim of the present study was to investigate function and properties of Treg of RA patients in response to purified polysaccharide glucuronoxylomannogalactan (GXMGal). METHODS: Flow cytometry and western blot analysis were used to investigate the frequency, function and properties of Treg cells. RESULTS: GXMGal was able to: i) induce strong increase of FOXP3 on CD4+ T cells without affecting the number of CD4+CD25+FOXP3+ Treg cells with parallel increase in the percentage of non-conventional CD4+CD25-FOXP3+ Treg cells; ii) increase intracellular levels of TGF-ß1 in CD4+CD25-FOXP3+ Treg cells and of IL-10 in both CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells; iii) enhance the suppressive activity of CD4+CD25+FOXP3+ and CD4+CD25-FOXP3+ Treg cells in terms of inhibition of effector T cell activity and increased secretion of IL-10; iv) decrease Th1 response as demonstrated by inhibition of T-bet activation and down-regulation of IFN-γ and IL-12p70 production; v) decrease Th17 differentiation by down-regulating pSTAT3 activation and IL-17A, IL-23, IL-21, IL-22 and IL-6 production. CONCLUSION: These data show that GXMGal improves Treg functions and increases the number and function of CD4+CD25-FOXP3+ Treg cells of RA patients. It is suggested that GXMGal may be potentially useful for restoring impaired Treg functions in autoimmune disorders and for developing Treg cell-based strategies for the treatment of these diseases.
Asunto(s)
Artritis Reumatoide/inmunología , Artritis Reumatoide/metabolismo , Polisacáridos/inmunología , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Citocinas/biosíntesis , Femenino , Humanos , Masculino , Persona de Mediana Edad , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismoRESUMEN
The identification of Haemophilus spp. from urogenital sites can be challenging due to the lack of appropriate media for culturing the organisms and the poor resolution of biochemical methods. By incorporating chocolate agar and 16S rRNA gene sequence analysis in our protocol to identify Haemophilus spp. from urinary specimens, we isolated and characterized 30 genetically homogeneous strains of a cryptic species that is phylogenetically close to, but distinct from, Haemophilus parainfluenzae. Commercial biochemical kits and VITEK 2 could not distinguish between the two species. Over 90â% of the strains were isolated from urine and the urogenital area, made possible with the inclusion of chocolate agar in our urine culture protocol. In contrast, no Haemophilus strains isolated from respiratory specimens were identified as the cryptic genospecies. The cryptic genospecies was associated with urinary tract infections (UTIs) in certain patient populations. Distinct from Haemophilus quentinii that also causes urogenital infection, the cryptic genospecies required V factor (NAD) but not X factor (haemin) to grow. The data indicated that 16S rRNA gene sequencing may be necessary in identifying Haemophilus species and that inaccurate categorization of Haemophilus strains isolated from urogenital specimens based on phenotypic characteristics may prevent accurate diagnosis of UTIs.
Asunto(s)
Haemophilus parainfluenzae/clasificación , Infecciones Oportunistas/microbiología , ARN Bacteriano/genética , ARN Ribosómico 16S/genética , Infecciones Urinarias/microbiología , Regulación Bacteriana de la Expresión Génica , Especiación Genética , Haemophilus parainfluenzae/genética , Haemophilus parainfluenzae/aislamiento & purificación , Humanos , Datos de Secuencia Molecular , Infecciones Oportunistas/epidemiología , Filogenia , Infecciones Urinarias/epidemiologíaRESUMEN
The effector activity of antibodies is dependent on engagement with Fcγ receptors (FcγRs) and activation of the associated intracellular signaling pathways. Preclinical evaluation of therapeutic humanized or chimeric mAbs to study the interactions of their Fc regions with FcγRs is hampered by substantial structural and functional FcγR diversity among species. In this report, we used mice expressing only human FcγRs to evaluate the contribution of FcγR-mediated pathways to the neutralizing activity of an anti-anthrax toxin chimeric mAb. We observed that the protective activity of this mAb was highly dependent upon FcγR engagement, with minimal protection against anthrax toxin observed in FcγR-deficient mice following mAb administration. We generated anti-anthrax toxin mAbs with specific Fc domain variants with selectively enhanced affinity for particular human FcγRs and assessed their activity in FcγR-humanized mice. We determined that Fc domain variants that were capable of selectively engaging activating FcγRs substantially enhanced the in vitro and in vivo activity of anthrax toxin-neutralizing antibodies. These findings indicate that the application of Fc domain engineering is a feasible strategy to enhance toxin-neutralizing activity and suggest that engineered antitoxin antibodies will have improved therapeutic efficacy.
Asunto(s)
Anticuerpos Neutralizantes/química , Inmunoglobulina G/química , Receptores de IgG/química , Animales , Carbunco/terapia , Anticuerpos Monoclonales/química , Citotoxicidad Celular Dependiente de Anticuerpos/inmunología , Antígenos Bacterianos/química , Antitoxinas/química , Toxinas Bacterianas/química , Ensayo de Inmunoadsorción Enzimática , Células HEK293 , Humanos , Concentración 50 Inhibidora , Ratones , Ratones Transgénicos , Ingeniería de Proteínas , Estructura Terciaria de Proteína , Proteínas Recombinantes/química , Transducción de Señal , Resonancia por Plasmón de SuperficieRESUMEN
Helcococcus spp. are Gram-positive, catalase-negative, facultatively anaerobic cocci that are associated with wound and prosthetic joint infections as well bacteremia and empyema. Five Helcococcus spp. strains were isolated from our patient population, including 2 strains of Helcococcus kunzii from trauma-associated wounds, 2 Helcococcus sueciensis strains from blood and abscess, and a novel Helcococcus spp. strain from blood associated with urosepsis. Based on the phenotypic and phylogenetic evidence, we propose that the unknown bacterium be classified as Helcococcus seattlensis sp. nov. We found that all 5 tested Helcococcus strains grew as satellite colonies around Staphylococcus aureus and, interestingly, both H. kunzii strains were isolated together with S. aureus. In addition to 16S rRNA gene sequencing, conventional methods for leucine aminopeptidase (LAP) and pyrrolidonyl arylamidase (PYR) testing can be cost-effective and efficient for differentiation of Helcococcus spp. from Abiotrophia and Granulicatella species. Using nonstandard methods, we found that all tested Helcococcus spp. had high MICs of >4/76 µg/ml for trimethoprim-sulfamethoxazole, an antibiotic commonly used to treat urinary tract infections. High MICs for erythromycin, azithromycin, and clindamycin, and intermediate to high MICs for moxifloxacin, levofloxacin, and gentamicin were also observed among the Helcococcus strains.
Asunto(s)
Bacterias Grampositivas/aislamiento & purificación , Infecciones por Bacterias Grampositivas/diagnóstico , Infecciones por Bacterias Grampositivas/microbiología , Sepsis/diagnóstico , Sepsis/microbiología , Infecciones Urinarias/diagnóstico , Infecciones Urinarias/microbiología , Antibacterianos , Técnicas de Tipificación Bacteriana , Sangre/microbiología , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Bacterias Grampositivas/clasificación , Bacterias Grampositivas/genética , Humanos , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Infecciones Urinarias/complicacionesRESUMEN
During infection, humoral immunity produces a polyclonal response with various immunoglobulins recognizing different epitopes within the microbe or toxin. Despite this diverse response, the biological activity of an antibody (Ab) is usually assessed by the action of a monoclonal population. We demonstrate that a combination of monoclonal antibodies (mAbs) that are individually disease enhancing or neutralizing to Bacillus anthracis protective antigen (PA), a component of anthrax toxin, results in significantly augmented protection against the toxin. This boosted protection is Fc gamma receptor (FcγR) dependent and involves the formation of stoichiometrically defined mAb-PA complexes that requires immunoglobulin bivalence and simultaneous interaction between PA and the two mAbs. The formation of these mAb-PA complexes inhibits PA oligomerization, resulting in protection. These data suggest that functional assessments of single Abs may inaccurately predict how the same Abs will operate in polyclonal preparations and imply that potentially therapeutic mAbs may be overlooked in single Ab screens.
Asunto(s)
Anticuerpos Bloqueadores/inmunología , Anticuerpos Neutralizantes/inmunología , Toxinas Bacterianas/inmunología , Animales , Carbunco/inmunología , Anticuerpos Antibacterianos/inmunología , Anticuerpos Monoclonales/inmunología , Antígenos Bacterianos/inmunología , Bacillus anthracis/inmunología , Femenino , Inmunoglobulinas/inmunología , Ratones , Ratones Endogámicos BALB CRESUMEN
Monoclonal antibodies (MAbs) are potential therapeutic agents against Bacillus anthracis toxins, since there is no current treatment to counteract the detrimental effects of toxemia. In hopes of isolating new protective MAbs to the toxin component lethal factor (LF), we used a strain of mice (C57BL/6) that had not been used in previous studies, generating MAbs to LF. Six LF-binding MAbs were obtained, representing 3 IgG isotypes and one IgM. One MAb (20C1) provided protection from lethal toxin (LeTx) in an in vitro mouse macrophage system but did not provide significant protection in vivo. However, the combination of two MAbs to LF (17F1 and 20C1) provided synergistic increases in protection both in vitro and in vivo. In addition, when these MAbs were mixed with MAbs to protective antigen (PA) previously generated in our laboratory, these MAb combinations produced synergistic toxin neutralization in vitro. But when 17F1 was combined with another MAb to LF, 19C9, the combination resulted in enhanced lethal toxicity. While no single MAb to LF provided significant toxin neutralization, LF-immunized mice were completely protected from infection with B. anthracis strain Sterne, which suggested that a polyclonal response is required for effective toxin neutralization. In total, these studies show that while a single MAb against LeTx may not be effective, combinations of multiple MAbs may provide the most effective form of passive immunotherapy, with the caveat that these may demonstrate emergent properties with regard to protective efficacy.