RESUMEN
A 67-year-old woman with anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis was not vaccinated against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and was on multiple immunosuppressive drugs. She was hospitalized because of interstitial shadowing in the lungs and diagnosed with persistent coronavirus disease 2019 (COVID-19). Despite treatment with a recombinant monoclonal antibody and antivirals, her symptoms persisted and she lacked a specific antibody response. She tested negative for SARS-CoV-2 antigen after the second antiviral treatment, and a subsequent chest radiograph showed improvement. However, the antibody levels did not change. This case highlights the importance of careful monitoring of the SARS-CoV-2 antigen and antibody levels during COVID-19 treatment in patients with immunosuppression.
Asunto(s)
Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos , COVID-19 , Huésped Inmunocomprometido , SARS-CoV-2 , Humanos , Anciano , Femenino , COVID-19/inmunología , COVID-19/complicaciones , COVID-19/diagnóstico , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/tratamiento farmacológico , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/inmunología , Vasculitis Asociada a Anticuerpos Citoplasmáticos Antineutrófilos/sangre , SARS-CoV-2/inmunología , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Inmunosupresores/uso terapéutico , Tratamiento Farmacológico de COVID-19 , Antivirales/uso terapéutico , Antígenos Virales/inmunologíaRESUMEN
BACKGROUND: COVID-19 has become widespread in Japanese children. However, the impact of varying immunization coverage on the seroprevalence of SARS-CoV-2 in children is unknown. METHODS: We examined the SARS-CoV-2 antibody in children aged 0 to 18 who were hospitalized at a university hospital from June 2020 through May 2023. The SARS-CoV-2 anti-nucleoprotein (N) antibody and anti-RBD spike (S) protein antibody was measured. RESULTS: A total of 586 cases were enrolled. The median age was 4 years old (interquartile range 1-9), and 362 (61.8 %) were male. The seroprevalence of anti-S antibodies gradually increased from October 2021 and reached 60 percent by early 2023. The anti-N antibody increased starting in January 2022 and reached 50 percent in May 2023. There was a discrepancy in the seroprevalence of anti-S and N antibodies in children 0 years of age or 12 years and older until the fall of 2022. This discrepancy was minimal for children 1-4 years of age and relatively small in the 5-11-year-old group. DISCUSSION: The data suggests that approximately half of the children in our cohort had been infected with SARS-CoV-2 by May 2023. The discrepancy in seropositivity between the anti-S and N antibodies corresponded to the reported vaccine uptake of each target age group, which suggested protective effects of immunization. However, this effect appeared to diminish after early 2023. CONCLUSION: Age dependent discrepancy between SARS-CoV-2 anti-N and anti-S antibody in children reflected differences in vaccine coverage.
Asunto(s)
Anticuerpos Antivirales , Vacunas contra la COVID-19 , COVID-19 , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Adolescente , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Factores de Edad , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Proteínas de la Nucleocápside de Coronavirus/inmunología , COVID-19/inmunología , COVID-19/prevención & control , COVID-19/epidemiología , Vacunas contra la COVID-19/inmunología , Vacunas contra la COVID-19/administración & dosificación , Japón/epidemiología , Fosfoproteínas/inmunología , SARS-CoV-2/inmunología , Estudios Seroepidemiológicos , Glicoproteína de la Espiga del Coronavirus/inmunología , Cobertura de Vacunación/estadística & datos numéricosRESUMEN
Urinary tract infection (UTI) and bloodstream infection (BSI) caused by extended-spectrum ß-lactamase (ESBL)-producing bacteria are important healthcare problems. Appropriate infection management requires the direct detection of organisms in clinical specimens. We assessed the capability of the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based MBT STAR-Cepha kit to detect ESBL producers in clinical urine and blood samples. Over a 1-year period, 90 urine samples and 55 positive monomicrobial (Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, or Proteus mirabilis) blood cultures were collected from patients with UTI or BSI at Hamamatsu University Hospital. ß-lactamase activity in these samples was directly detected using the MBT STAR-Cepha kit, and the results were compared with those of antimicrobial susceptibility testing and polymerase chain reaction detection assay for the isolates. In receiver operating characteristic curve analysis, the kit assay showed low accuracy in detecting ESBL producers in urine samples (area under the curve [AUC], 0.69). Meanwhile, the AUC for detecting all ESBL-producing bacteria in positive blood cultures was 0.81. The kit assay detected cefotaxime (CTX) resistance (mainly in CTX-M-type ESBL producers) with high accuracy in positive blood cultures; however, it did not accurately detect ESBL producers in urine samples and CTX-susceptible isolates with other ESBL-associated genes (e.g., TEM and SHV types) in positive blood cultures. MBT STAR-Cepha testing can accurately discriminate CTX-resistant ESBL producers in BSI cases and thus can contribute to effective infection management. The results suggest that different sample types, antibiotic resistance profiles, and resistance genes can affect the kit performance.
Asunto(s)
Infecciones Urinarias , beta-Lactamasas , Humanos , beta-Lactamasas/genética , beta-Lactamasas/análisis , Cultivo de Sangre , Cefotaxima , Escherichia coli , Klebsiella pneumoniae , Espectrometría de Masas , Infecciones Urinarias/diagnóstico , Infecciones Urinarias/microbiología , Rayos Láser , Pruebas de Sensibilidad Microbiana , Antibacterianos/farmacologíaRESUMEN
SARS-CoV-2 nucleic acid detection tests enable rapid virus detection; however, it is challenging to identify genotypes to comprehend the local epidemiology and infection routes in real-time qRT-PCR. At the end of June 2022, our hospital experienced an in-hospital cluster of COVID-19. When examined using the GeneXpert® System, the cycle threshold (Ct) value of the N2 region of the nucleocapsid gene of SARS-CoV-2 was approximately 10 cycles higher than that of the envelope gene. Sanger sequencing revealed a G29179T mutation in the primer and probe binding sites. A review of past test results revealed differences in Ct values in 21 of 345 SARS-CoV-2-positive patients, of which 17 cases were cluster-related and 4 were not. Including these 21 cases, 36 cases in total were selected for whole-genome sequencing (WGS). The viral genomes in the cluster-related cases were identified as BA.2.10, and those in the non-cluster cases were closely related and classified as being downstream of BA.2.10 and other lineages. Although WGS can provide comprehensive information, its use is limited in various laboratory settings. A measurement platform reporting and comparing Ct values of different target genes can improve test accuracy, enhance our understanding of infection spread, and be applied to the quality control of reagents.
RESUMEN
Vaccines against SARS-CoV-2 with good efficacy are now available worldwide. However, gained immunity diminishes over time. Here, we investigate the course of both humoral and cell-mediated immunity in response to three doses of the Pfizer mRNA BNT162b2 SARS-CoV-2 vaccine in healthcare workers in Japan. SARS-CoV-2 anti-receptor-binding domain (RBD) antibodies (total Ig, IgG), neutralizing antibodies (NAb), and ELISpot were measured in serum and whole blood samples collected after each vaccine dose. ELISpot numbers were higher than the cutoff values in most participants at all times. It was suggested that the difference in behavior between humoral immunity and cell-mediated immunity with age is complementary. Anti-RBD total Ig, IgG, and NAb indicated a high correlation at each time point after vaccine doses. Total Ig was retained long-term after the second dose and increased significantly faster by the booster dose than IgG. Nab levels of all subjects were ≤20% six months after the second dose, and the correlation coefficient was greatly reduced. These are due to the avidity of each antibody and differences among commercial kits, which may affect the evaluation of immunokinetics in previous COVID-19 studies. Therefore, it is necessary to harmonize reagents categorized by the same characteristics.
RESUMEN
The gold standard test for identifying SARS-CoV-2, the causative agent of COVID-19, is polymerase chain reaction (PCR). Despite their limited sensitivity, SARS-CoV-2 antigen rapid diagnostic tests are vital tools in the fight against viral spread. Owing to its simplicity and low cost, the lateral flow assay (LFA) is the most extensively used point-of-care diagnostic test. Here, we report a newly designed LFA-NanoSuit method (LNSM) that works in conjunction with desktop scanning electron microscopy (SEM) to detect SARS-CoV-2. LNSM requires no standard SEM treatment, avoids cellulose and residual buffer deformation, and enables the capture of high-resolution images of antibody-labeled gold/platinum particles reacting with SARS-CoV-2 antigens. To assess its applicability, we compared clinical SARS-CoV-2 samples via visual detection of LFA, LSNM detection of LFA, and real-time reverse transcription-PCR (qRT-PCR). Compared to qRT-PCR, LNSM showed 86.7% sensitivity (26/30; 95% confidence interval (CI): 69.28-96.24%) and 93.3% specificity (14/15; 95% CI: 68.05-99.83%) for SARS-CoV-2. In samples with a relatively low SARS-CoV-2 RNA copy number (30 < Ct ≤ 40), the sensitivity of LNSM was greater (73.3%) than that of visual detection (0%). A simple, sensitive, and quantitative LNSM can be used to diagnose SARS-CoV-2.
RESUMEN
Rapid and simple detection of extended-spectrum ß-lactamase (ESBL) and carbapenemase is essential for antimicrobial treatment and infection control. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS)-based MBT STAR-Cepha and MBT STAR-Carba kits have been developed with simplified MBT STAR-BL operations. However, the utility of these kits has not been fully examined in clinical microbiology laboratories. In this study, we evaluated the utility of MALDI-TOF MS-based MBT STAR-Cepha and MBT STAR-Carba kits to detect ESBL and carbapenemase-producing bacteria, and compared it with the conventional broth microdilution test and PCR amplification assay. We found that the MBT STAR-Cepha kit efficiently distinguished resistant strains of third-generation cephalosporin susceptibility phenotypes and non-SHV-type ESBL producers. In the receiver operating characteristic analysis, the area under the receiver operating characteristic curve (AUC) for detecting third-generation cephalosporin resistance using the MBT STAR-Cepha kit was 0.97-1.00, but the AUC for detecting ESBL producers was 0.64. In addition, we showed that the MBT STAR-Carba kit enabled the accurate detection of antimicrobial resistance by IMP-type carbapenemase producers. The AUC for detecting carbapenemase producers was 1.00. The results suggested that the target bacterial strains, antimicrobial susceptibility phenotypes, and resistance genes were important for the utility of the MALDI-TOF MS-based MBT STAR-Cepha and MBT STAR-Carba kits in bacterial routine diagnostics.
Asunto(s)
Bacterias/aislamiento & purificación , Proteínas Bacterianas/metabolismo , Técnicas de Tipificación Bacteriana/métodos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , beta-Lactamasas/metabolismo , Antibacterianos/farmacología , Bacterias/efectos de los fármacos , Bacterias/enzimología , Proteínas Bacterianas/genética , Farmacorresistencia Bacteriana , Pruebas de Sensibilidad Microbiana , Juego de Reactivos para Diagnóstico , beta-Lactamasas/genéticaRESUMEN
The emergence of daptomycin (DAP) resistant Enterococcus species has increased worldwide, but the mechanisms for DAP resistance are not fully understood. We report a case of DAP resistant Enterococcus faecalis, from a clinical sample of a patient with diabetic ulcers, after DAP therapy. Whole-genome sequencing analysis revealed that the isolate had a loss-of-function point mutation within liaX encoding DAP-sensing surface protein, which inhibits the LiaFSR systems and cell membrane remodeling. This is the first case report of a clinical DAP resistant E. faecalis with a mutation in liaX.
Asunto(s)
Daptomicina , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Proteínas Bacterianas/genética , Membrana Celular , Daptomicina/farmacología , Daptomicina/uso terapéutico , Farmacorresistencia Bacteriana/genética , Enterococcus faecalis/genética , Humanos , Proteínas de la Membrana , Pruebas de Sensibilidad Microbiana , Mutación/genéticaRESUMEN
Rapid and sensitive detection of extended-spectrum ß-lactamases (ESBLs) is essential for infection control and antimicrobial treatment. Recently, a matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)-based MBT STAR-BL software module has been used for detecting ß-lactamase activity; however, this system cannot differentiate ESBL producing bacteria from other third-generation cephalosporin-resistant strains. In this study, we utilized a MALDI-TOF MS-based MBT STAR-BL method to identify ESBL activity with ß-lactamase inhibitors. A cefotaxime (CTX) hydrolysis assay, ß-lactamase inhibition, clavulanic acid (CVA), and sulbactam (SBT) were used for detecting ESBL producers with the MBT STAR-BL software module. This software module automatically calculated the logRQ values in each assay. logRQ is the logarithm of the ratio of the summed hydrolyzed peak intensities to the summed non-hydrolyzed peak intensities and measured the efficiency of antibiotic hydrolysis. We divided the logRQ level of the ß-lactamase inhibition assay by the logRQ value in the CTX hydrolysis assay, and we used this logRQ ratio as a measure of ß-lactamase inhibition efficiency. We assessed the logRQ ratio calculated by this novel method for detecting ESBL producers in 132 Enterobacteriaceae. We performed the MALDI-TOF MS-based MBT STAR-BL approach with ß-lactamase inhibitors for detecting ESBL producers and showed that the results of the inhibition assay with ß-lactamase inhibitors depended on types of bacterial species. Furthermore, we improved elapsed times and accuracy in MBT STAR-BL methods by using proper ß-lactamase inhibitors against specific bacterial strains to compare with the conventional standard lab method. The results suggest that the target bacterial species and ß-lactamase inhibitors used were important for the utility of the MALDI-TOF MS-based MBT STAR-BL software module.
Asunto(s)
Enterobacteriaceae/efectos de los fármacos , Programas Informáticos , Inhibidores de beta-Lactamasas/farmacología , beta-Lactamasas/análisis , Antibacterianos/farmacología , Cefotaxima/farmacología , Ácido Clavulánico/farmacología , Enterobacteriaceae/enzimología , Enterobacteriaceae/genética , Humanos , Hidrólisis , Pruebas de Sensibilidad Microbiana , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Sulbactam/farmacologíaRESUMEN
PURPOSE: In infectious disease therapy, administration of adequate antimicrobial agents is essential for preventing the emergence and spread of resistant bacteria. However, conventional antimicrobial susceptibility testing (AST), based on bacterial growth, is time consuming; therefore, a rapid, simple assay is needed for the timely selection of appropriate antibiotics in clinical laboratories. Here, we established a simple, cost-effective, time-saving and highly sensitive AST assay based on loop-mediated isothermal amplification (LAMP). METHODOLOGY: The targeted bacteria were cultivated for a short period with or without antibiotic before the LAMP reaction. The time to detect a positive reaction with LAMP was used to generate a threshold time (Tt) value, and subtraction of the Tt value for an antibiotic-free sample from the Tt value in an antibiotic-exposed sample generated the ΔTt value, which was used as a marker of antimicrobial susceptibility. The ΔTt value generated using the LAMP-based assay simply and quickly detected antimicrobial resistance in clinical Escherichia coli isolates. RESULTS: Detection of susceptibility to levofloxacin using the ΔTt value perfectly matched with the results of the conventional assay. In addition, the sensitivity and specificity for the detection of ampicillin, trimethoprim-sulfamethoxazole and fosfomycin resistance were 100â%, 93.8â%, 100â% and 80.0â%, 93.3â%, 97.6â%, respectively. CONCLUSION: These results showed that this LAMP-based AST has high sensitivity and specificity for detecting resistant strains and a significant time advantage compared with the conventional method.
Asunto(s)
Antiinfecciosos/farmacología , Farmacorresistencia Bacteriana , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , ADN Bacteriano/química , ADN Ribosómico/química , Escherichia coli/clasificación , Escherichia coli/genética , Infecciones por Escherichia coli/microbiología , Humanos , Técnicas de Dilución del Indicador , Pruebas de Sensibilidad Microbiana/normas , Fenotipo , ARN Ribosómico 16S/genética , Sensibilidad y Especificidad , Infecciones Urinarias/microbiología , Orina/microbiología , beta-Lactamasas/genéticaRESUMEN
Limited use of linezolid for treating methicillin-resistant Staphylococcus aureus (MRSA) infection was approved in Japan in 2006. We report here the status of linezolid-resistant MRSAs in Japan. Eleven linezolid-resistant clinical isolates from 11 patients at six hospitals were collected from 2006 through 2008. The minimal inhibitory concentration (MIC) of linezolid in these strains varied from 8 to 64 µg/ml. All strains had at least one G2576T mutation in the chromosomal gene(s) encoding domain V of the 23S ribosomal RNA (rRNA). Chromosomal DNA encoding five copies of the domain V region was analyzed by polymerase chain reaction (PCR). Strains with the linezolid MICs of 64, 32, 16, and 8 µg/ml had the G2576T mutation(s) in four, three (or four), two, and one copy of the 23S rRNA genes, respectively. These results suggest that the level of linezolid resistance seems to be roughly correlated with the number of mutations in the genes encoding 23S rRNA. DNA samples from all 11 strains were subjected to pulsed-field gel electrophoresis and were classified into seven independent clones having >92% identity. Among the 11 patients, five had been treated with linezolid and the remainder, in two hospitals, had no history of prior linezolid use. The results suggested possible nosocomial infections by linezolid-resistant MRSA.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Linezolid/farmacología , Infecciones Estafilocócicas , Staphylococcus aureus/aislamiento & purificación , ADN Bacteriano/genética , Genoma Bacteriano , Humanos , Japón , ARN Ribosómico 23S/genética , Infecciones Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/genética , Factores de TiempoRESUMEN
We conducted an antibiotic susceptibility survey of 830 blood-borne methicillin resistant Staphylococcus aureus collected from nationwide hospitals in Japan over a three-year period from January 2008 through May 2011. Antibiotic susceptibility was judged according to the criteria recommended by the Clinical Laboratory Standard Institute. Over 99% of the MRSA showed to be susceptible to teicoplanin, linezolid, sulfamethoxazole/trimethoprim and vancomycin, and over 97% of them were susceptible to daptomycin, arbekacin and rifampin. The majority of the MRSA strains showed resistant to minocycline, meropenem, imipenem, clindamycin, ciprofloxacin, cefoxitin, and oxacillin in the rates of 56.6, 72.9, 73.7, 78.7, 89.0, 99.5, and 99.9%, respectively. Among the MRSA strains, 72 showed reduced susceptibility to vancomycin, including 8 strains (0.96%) of vancomycin-intermediate S. aureus (VISA), 54 (6.51%) of heterogeneous vancomycin-intermediate S. aureus (hVISA), and 55 (5.63%) of ß-lactam antibiotics-induced vancomycin resistant S. aureus (BIVR). Unexpectedly, among the 54 hVISA and 55 BIVR, 45 isolates (83.3% and 81.8%, respectively) showed both hVISA and BIVR phenotypes. A new trend of vancomycin resistance found in this study was that VISA strains were still prevalent among the bacteremic specimens. The high rates of the hVISA/BIVR two-phenotypic vancomycin resistance, and the prevalence of VISA in the bloodborne MRSA call attention in the MRSA epidemiology in Japan.
Asunto(s)
Antibacterianos/uso terapéutico , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Infecciones Estafilocócicas/microbiología , Humanos , Japón , Pruebas de Sensibilidad Microbiana/métodos , Infecciones Estafilocócicas/sangre , Infecciones Estafilocócicas/tratamiento farmacológico , Resistencia a la Vancomicina/fisiología , beta-Lactamas/uso terapéuticoRESUMEN
The clinical implications of free linezolid monitoring have not been fully clarified in critically ill patients. The aim of this study was to evaluate the variability in pharmacokinetics of free linezolid and its relationship with susceptibility to meticillin-resistant Staphylococcus aureus (MRSA) in critically ill patients. Twenty critically ill MRSA-infected patients receiving intravenous linezolid were enrolled. Blood specimens were collected by 12-h sampling after dosing at Day 7. The medians (interquartile range) of the minimum free concentration, area under the concentration-time curve of total and free linezolid from 0 to 24 h (AUC(0-24) and fAUC(0-24), respectively) and percentage bound were 9.9 µg/mL (5.2-15 µg/mL), 495 µgh/mL (291-695 µgh/mL), 385 µgh/mL (242-528 µgh/mL) and 23% (15-28%), respectively. The medians of the AUC(0-24) and fAUC(0-24) to minimum inhibitory concentration ratios (AUC/MIC and fAUC/MIC) were 248 (144-347) and 192 (109-264), respectively. Two patients failed to achieve adequate levels of AUC/MIC and fAUC/MIC for linezolid. The percentage bound of linezolid in hypoalbuminaemic patients was significantly lower than in non-hypoalbuminaemic patients. A significant correlation was observed between fAUC(0-24) and creatinine clearance. In addition, the fAUC(0-24) was correlated with the minimum free concentration. In conclusion, the plasma level of free linezolid was variable in critically ill patients with renal dysfunction and hypoalbuminaemia. This finding suggests that the monitoring of free linezolid is necessary in critically ill patients.
Asunto(s)
Acetamidas/farmacología , Acetamidas/farmacocinética , Antibacterianos/farmacología , Antibacterianos/farmacocinética , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Oxazolidinonas/farmacología , Oxazolidinonas/farmacocinética , Plasma/química , Acetamidas/administración & dosificación , Administración Intravenosa , Anciano , Antibacterianos/administración & dosificación , Área Bajo la Curva , Enfermedad Crítica , Humanos , Linezolid , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Oxazolidinonas/administración & dosificación , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/microbiologíaRESUMEN
The aim of this study was to evaluate Etest for detectability of linezolid-resistant meticillin-resistant Staphylococcus aureus (MRSA). The MIC of linezolid obtained by the Etest method in 18 linezolid-resistant strains of MRSA was compared with that obtained using standard agar and broth dilution methods according to Clinical and Laboratory Standards Institute guidelines. The mean linezolid MIC obtained by Etest in 18 linezolid-resistant strains of MRSA using Mueller-Hinton (MH) agar was 12.6-fold lower than that obtained by the agar dilution method, with the result that 78â% of the linezolid-resistant strains were incorrectly classified as linezolid-susceptible. The MIC of linezolid by Etest on brain-heart infusion (BHI) agar had a mean value 2.5-fold lower than that obtained by the agar dilution method, suggesting that replacing MH agar with BHI agar considerably improved the detectability of linezolid-resistant MRSA. Use of blood agar (MH agar supplemented with 5â% sheep blood) and 48 h of incubation resulted in 100â% agreement with the agar and broth dilution methods. Thus, this study revealed that the Etest on MH agar and BHI agar yielded false-negative results in a significant fraction of the linezolid-resistant MRSA. Hence, the use of blood agar and prolonged incubation is highly recommended for the accurate detection of linezolid-resistant MRSA using Etest.
Asunto(s)
Acetamidas/farmacología , Antibacterianos/farmacología , Medios de Cultivo/química , Farmacorresistencia Bacteriana , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Oxazolidinonas/farmacología , Humanos , Linezolid , Pruebas de Sensibilidad Microbiana/métodos , Sensibilidad y EspecificidadRESUMEN
The antibacterial activity of meropenem (MEPM) and other parenteral antibiotics against clinical isolates of 2655 strains including 810 strains of Gram-positive bacteria, 1635 strains of Gram-negative bacteria, and 210 strains of anaerobic bacteria obtained from 30 medical institutions during 2009 was examined. The results were as follows; (1) MEPM was more active than the other carbapenem antibiotics tested against Gram-negative bacteria, especially against enterobacteriaceae and Haemophilus influenzae. MEPM was also active against most of the species tested in Gram-positive and anaerobic bacteria, except for multidrug resistant strains including methicillin-resistant Staphylococcus aureus (MRSA). (2) MEPM maintained potent and stable antibacterial activity against Pseudomonas aeruginosa. The proportion of MEPM-resistant strains to ciprofloxacin-resistant strains or imipenem-resistant strains were 53.1% and 58.0% respectively. (3) The proportion of extended-spectrum beta-lactamase (ESBL) strains was 3.1% (26 strains) in enterobacteriaceae. And the proportion of metallo-beta-lactamase strains was 2.0% (6 strains) in P. aeruginosa. (4) Of all species tested, there were no species except for Bacteroides fragilis group, which MIC90 of MEPM was more than 4-fold higher than those in our previous study. Therefore, there is almost no significant decrease in susceptibility of clinical isolates to meropenem. In conclusion, the results from this surveillance study suggest that MEPM retains its potent and broad antibacterial activity and therefore is a clinically useful carbapenem for serious infections treatment at present, 14 years passed after available for commercial use in Japan.
Asunto(s)
Antibacterianos/farmacología , Bacterias Anaerobias/efectos de los fármacos , Bacterias Anaerobias/aislamiento & purificación , Infecciones Bacterianas/microbiología , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/aislamiento & purificación , Bacterias Grampositivas/efectos de los fármacos , Bacterias Grampositivas/aislamiento & purificación , Tienamicinas/farmacología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Preescolar , Formas de Dosificación , Farmacorresistencia Bacteriana , Humanos , Lactante , Recién Nacido , Japón , Meropenem , Persona de Mediana Edad , Sistema Respiratorio/microbiología , Factores de Tiempo , Orina/microbiología , Adulto JovenRESUMEN
Limited use of linezolid for treating methicillin-resistant Staphylococcus aureus (MRSA) infection was approved in Japan in 2006. We report here the status of linezolid-resistant MRSAs in Japan. Eleven linezolid-resistant clinical isolates from 11 patients at six hospitals were collected from 2006 through 2008. The minimal inhibitory concentration (MIC) of linezolid in these strains varied from 8 to 64 µg/ml. All strains had at least one G2576T mutation in the chromosomal gene(s) encoding domain V of the 23S ribosomal RNA (rRNA). Chromosomal DNA encoding five copies of the domain V region was analyzed by polymerase chain reaction (PCR). Strains with the linezolid MICs of 64, 32, 16, and 8 µg/ml had the G2576T mutation(s) in four, three (or four), two, and one copy of the 23S rRNA genes, respectively. These results suggest that the level of linezolid resistance seems to be roughly correlated with the number of mutations in the genes encoding 23S rRNA. DNA samples from all 11 strains were subjected to pulsed-field gel electrophoresis and were classified into seven independent clones having >92% identity. Among the 11 patients, five had been treated with linezolid and the remainder, in two hospitals, had no history of prior linezolid use. The results suggested possible nosocomial infections by linezolid-resistant MRSA.
Asunto(s)
Acetamidas/farmacología , Antibacterianos/farmacología , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Oxazolidinonas/farmacología , Infecciones Estafilocócicas/microbiología , Acetamidas/uso terapéutico , Antibacterianos/uso terapéutico , Infección Hospitalaria , ADN Bacteriano/genética , Farmacorresistencia Bacteriana Múltiple , Electroforesis en Gel de Campo Pulsado , Hospitales , Humanos , Japón , Linezolid , Staphylococcus aureus Resistente a Meticilina/genética , Pruebas de Sensibilidad Microbiana , Oxazolidinonas/uso terapéutico , Reacción en Cadena de la Polimerasa , ARN Ribosómico 23S/genética , Infecciones Estafilocócicas/tratamiento farmacológicoRESUMEN
A higher inoculum size of beta-lactamase-positive Haemophilus influenzae is reported to increase minimum inhibitory concentrations (MICs) for beta-lactams. However, the effect of inoculum size of beta-lactamase-negative, ampicillin-resistant H. influenzae (BLNAR) on MICs for carbapenems has not been investigated. This study evaluated the effect of inoculum size on MICs for carbapenems and other beta-lactams in nine clinical isolates of BLNAR. The MICs were determined by both the standard method described by the Clinical and Laboratory Standards Institute (final inoculum size of 5 x 10(5) colony-forming units [CFU]/ml) and a modified method (final inoculum size of 5 x 10(6) CFU/ml) using viable cell counts. The findings showed that the higher inoculum size increased MICs for imipenem, meropenem, panipenem, biapenem, ampicillin, ceftazidime, and ceftriaxone. The inoculum effect (4 log(2) dilution or a greater increase in the MIC) with imipenem, meropenem, panipenem, and biapenem was found in three, five, two, and two isolates, respectively. The magnitude of the inoculum effect for panipenem significantly increased with the levels of MICs, but correlation between them for the others was not statistically significant. The mutations of penicillin-binding protein genes had little relevance to the reduced susceptibility to carbapenems or to the magnitude of the inoculum effect. These results suggest that MIC determination using turbidity can produce interpretive errors in the antimicrobial susceptibility testing of BLNAR for carbapenems because of their inoculum effect. Thus, accurate adjustment of inoculum size, such as viable cell count, is helpful for confirming the true MICs when the isolates are interpreted as "resistant" by turbidity-based MIC determination.
Asunto(s)
Resistencia a la Ampicilina , Antibacterianos/farmacología , Haemophilus influenzae/efectos de los fármacos , beta-Lactamas/farmacología , Pruebas de Sensibilidad Microbiana , Proteínas de Unión a las Penicilinas/genéticaRESUMEN
Antimicrobial susceptibilities for fosfomycin (FOM), cephalexin, cefpodoxime, cefdinir, cefditren, ampicillin, sulbactam/ampicillin, imipenem (IPM), panipenem, meropenem (MEPM), biapenem, levofloxacin (LVFX), gatifloxacin, pazufloxacin, prulifloxacin and sulfamethoxazole/trimethoprim were determined by an agar dilution method using Mueller-Hinton agar (MHA) in Escherichia coli, Klebsiella spp., Serratia marcescens, Citrobacter spp., Enterobacter spp. and Proteus mirabilis, which were isolated from patients in 2003-2004. Those for FOM were determined by the agar dilution methods using MHA containing glucose-6-phosphate (G6P) under aerobic conditions, MHA under anaerobic conditions and nutrient agar under aerobic conditions. Those for FOM, LVFX, IPM and MEPM were also determined by an Etest method. The results by the agar dilution method showed that carbapenems had good antibacterial activities in all isolates, whereas MIC ranges for other antimicrobials were broad. Our results showed that the agar dilution method for FOM using MHA containing G6P under aerobic conditions provided reliable MICs in E. coli, which agreed with data previously reported. The results by the agar dilution method for LVFX, IPM and MEPM showed the high rate of agreement compared with those by the Etest method. In E. coli, the results for FOM by the agar dilution method using MHA containing G6P showed the high rate of agreement compared with the Etest results, although the rate was affected by bacterial species and culture conditions in various ways.
Asunto(s)
Antibacterianos/farmacología , Fosfomicina/farmacología , Técnicas Bacteriológicas , Citrobacter/efectos de los fármacos , Enterobacter/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Humanos , Klebsiella/efectos de los fármacos , Proteus mirabilis/efectos de los fármacos , Serratia marcescens/efectos de los fármacosRESUMEN
To ensure a complete response to fluoroquinolone therapy against Neisseria gonorrhoeae infections, rapid susceptibility determinations are required. We assessed a new approach, an isothermal chimeric primer-initiated amplification of nucleic acids (ICAN)/hybrid-chromatography method to detect rapidly fluoroquinolone resistance in N. gonorrhoeae. Comparison of the amplification results with fluoroquinolone minimum inhibitory concentrations (MICs), which were determined by an agar dilution method, showed that the new method accurately determined fluoroquinolone resistance in all ciprofloxacin- and/or gatifloxacin-resistant isolates, but agreed with results based on MICs in only 6 of 8 (75.0%) ciprofloxacin-susceptible and 7 of 12 (58.3%) gatifloxacin-susceptible isolates. Our results suggest that this method can rapidly and reliably detect point mutations in the gyrA gene as well as fluoroquinolone resistance in resistant isolates of N. gonorrhoeae.