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Tuberculous meningitis (TBM) is a common infectious disease of the central nervous system. Detection of cerebrospinal fluid (CSF) adenosine deaminase (ADA) activity for the diagnosis of TBM has a relatively high accuracy. Most previous reports determined ADA levels by following the colorimetric method of Giusti (endpoint assay). Recently, a Diazyme ADA assay kit was developed to determine CSF ADA levels. This study aimed to define the cutoff value of CSF ADA that is diagnostic for TBM with the Diazyme ADA assay kit. Adults with meningitis were included in the study. The diagnostic properties of CSF ADA for TBM as determined by the Diazyme ADA assay kit were assessed by the receiver operating characteristic curve, area under the curve, sensitivity, specificity, and likelihood ratios. There were 97 patients enrolled in the study, comprising 15 cases of TBM and 82 cases of non-TBM meningitis. The median CSF ADA activity level in the TBM group was significantly higher than in the non-TBM group (P = 0.002), with a mean difference of 14.5 U/L (95% CI: 5.3-23.8 U/L). A CSF ADA level of 6.1 U/L was the best cutoff value to differentiate between the TBM and non-TBM groups, with a sensitivity of 53.33%, a specificity of 89.02%, a positive likelihood ratio of 4.86, a negative likelihood ratio of 0.52, and an area under the curve of 0.75. A CSF ADA level of 6.1 U/L determined by the Diazyme ADA assay kit could be used as a diagnostic tool in the early diagnosis of TBM.
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Melioidosis caused by Burkholderia pseudomallei (Bp) is a public health threat. Genomic-epidemiology research on this deadly disease is scarce. We investigated whole-genome sequences of Bp isolates in relation to environmental source and drug susceptibility. In total, 563 Bp isolates were collected from 11 Northeast Thai provinces during the period 2004-2021. Patients (n = 530 isolates), infected animals (n = 8), and environmental sources (n = 25) provided samples. Phylogenetic analysis revealed genetic diversity among the Bp isolates, including numerous well-supported clusters of varying sizes. Through in-depth analysis of 38 monophyletic clades (MCs), we found eleven associated with province of origin (p-value < 0.001). Closely related clusters (CRCs) within MCs resembled MLST-identified "sequence types" (STs). We found 102 known and 52 novel STs. ST-70 was the most prevalent in this area (n = 78; 13.85%). Sample type (human/environmental) and sampling time intervals were not correlated with genetic distance among clonal Bp isolates. Some members of 12 CRCs had acquired resistance to co-trimoxazole and one against amoxicillin-clavulanic acid. Within Northeast Thailand, there is an association between Bp genotype and geographical origin.
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Antibacterianos , Burkholderia pseudomallei , Melioidosis , Filogenia , Burkholderia pseudomallei/genética , Burkholderia pseudomallei/efectos de los fármacos , Burkholderia pseudomallei/aislamiento & purificación , Tailandia/epidemiología , Humanos , Melioidosis/microbiología , Melioidosis/epidemiología , Antibacterianos/farmacología , Tipificación de Secuencias Multilocus , Animales , Pruebas de Sensibilidad Microbiana , Variación Genética , Secuenciación Completa del Genoma , Geografía , MasculinoRESUMEN
In this study, the covalently fixed "end-on" orientation of a monoclonal Listeria monocytogenes antibody (mAb-Lis) to amino terminated oligo (ethylene glycol)-capped gold nanoparticles (NH2-TEG-AuNPs) was used to fabricate an in-house lateral flow strip (LFS), namely, the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS. The aim was to evaluate the performance of the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS in detecting L. monocytogenes. The proposed LFS enabled the sensitive detection of L. monocytogenes in 15 min with a visual limit of detection of 102 CFU/mL. Quantitative analysis indicated an LOD at 10 CFU/mL. The fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS showed no cross-reactivity with other pathogenic bacteria and practical performance across different food matrices, including human blood, milk, and mushroom samples. Furthermore, the clinical performance of the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS for detecting L. monocytogenes was evaluated by using 12 clinical samples validated by the hemoculture method. It demonstrated excellent concordance with the reference methods, with no false-positive or false-negative results observed. Therefore, the fixed "end-on" Lis-mAb-NH-TEG-AuNPs LFS serves as a promising candidate for a point-of-care test (POCT), enabling the rapid, precise, and highly sensitive detection of L. monocytogenes in clinical samples and contaminated food.
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Anticuerpos Monoclonales , Oro , Listeria monocytogenes , Nanopartículas del Metal , Listeria monocytogenes/aislamiento & purificación , Listeria monocytogenes/inmunología , Oro/química , Nanopartículas del Metal/química , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/química , Humanos , Límite de Detección , Microbiología de Alimentos , Leche/microbiología , Leche/química , Anticuerpos Antibacterianos/química , Anticuerpos Antibacterianos/inmunología , Anticuerpos Inmovilizados/química , Anticuerpos Inmovilizados/inmunología , Animales , Listeriosis/microbiología , Listeriosis/diagnósticoRESUMEN
Staphylococcus aureus is one of the most common pathogens. The conventional workflow for identifying this organism is time-consuming and takes up to several days. Therefore, we developed a colloidal gold-based lateral flow immunoassay (LFIA) using human IgG as a conjugated antibody to detect S. aureus. One hundred and thirty-eight clinical isolates, including 79 S. aureus and 59 non-S. aureus were spiked in blood samples, and incubated at 37°C for 24 h. The bacterial antigens were simply extracted before being tested by the developed LFIA strips. The results were read by the naked eye within 15 min. Conventional PCR was used as a reference method. The sensitivity and specificity of the developed LFIA were 100% (95% CI: 94.2%-100.0% and 92.4%-100.0%, respectively) in spiked blood culture samples. The detection limits of the LFIA for the purified protein A and bacterial colonies were 10-3 µg/mL and 107 CFU/mL, respectively. The performance of the LFIA testing in 221 bacterial colony isolates and 118 positive blood culture bottles from three hospitals by their medical technologists showed 98.1% (95% CI: 94.1%-99.5%) and 89.7% (95% CI: 79.3%-95.4%) sensitivity, respectively. The LFIA is a quick, easy, and sensitive method for detecting S. aureus without expensive equipment. It might have the potential for early diagnosis of routine service in low-resource laboratories, leading to a rapid and effective treatment.IMPORTANCEIn this study, we modified our previously developed lateral flow immunoassay (LFIA) test for the detection of Staphylococcus aureus by using an in-house human IgG as a conjugated antibody instead of the specific commercial antibody. It gave comparable results to the former developed-LFIA test and helped cost reduction.
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Cultivo de Sangre , Staphylococcus aureus , Humanos , Inmunoensayo/métodos , Sensibilidad y Especificidad , Inmunoglobulina GRESUMEN
Melioidosis is caused by Burkholderia pseudomallei (Bp) acquired from the environment. Conventional identification methods for environmental Bp are challenging due to the presence of closely related species. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is accurate for bacterial identification, but has been little used to identify Bp from environmental samples. This study aims to evaluate MALDI-TOF MS for the identification of Bp and closely related species isolated from environmental samples in Thailand using whole-genome sequencing (WGS) as the gold standard, including determining the best sample preparation method for this purpose. We identified Bp (n = 22), Burkholderia spp. (n = 28), and other bacterial species (n = 32) using WGS. MALDI-TOF analysis of all Bp isolates yielded results consistent with WGS. A decision-tree algorithm identified 16 important variable peaks, using the protein extraction method (PEM), demonstrating distinct MALDI-TOF profiles for the three categories (Bp, Burkholderia spp. and "other bacterial species"). Three biomarker peaks (4060, 5196, and 6553 Da) could discriminate Bp from other Burkholderia and closely related species with 100% sensitivity and specificity. Hence, the MALDI-TOF technique has shown its potential as a species discriminatory tool, providing results comparable to WGS for classification and surveillance of environmental Bp.
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Burkholderia pseudomallei , Burkholderia , Microbiología del Suelo , Microbiología del Agua , Burkholderia/genética , Burkholderia/química , Burkholderia pseudomallei/genética , Burkholderia pseudomallei/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , TailandiaRESUMEN
Carbapenem-resistant Enterobacterales (CRE) possessing various carbapenemases, particularly the OXA-48 group, are now rapidly spreading and becoming a major public health concern worldwide. Phenotypic detection of OXA-48-like carbapenemases is still suboptimal due to their weak carbapenemase activity, whereas highly sensitive and specific polymerase chain reaction (PCR)-based methods take at least 3-4 h. We, therefore, developed a recombinase polymerase amplification (RPA) combined with lateral flow (LF) strip assay for the rapid detection of blaOXA-48-like in Enterobacterales. A total of 131 clinical isolates including 61 blaOXA-48-like-carrying Enterobacterales isolates and 70 Gram-negative bacilli isolates containing other bla genes were subjected to the RPA method performed under isothermal conditions at 37 °C within 10 min and visually inspected by LF strip within 5 min. The RPA-LF assay provided 100% sensitivity (95% confidence interval, 92.6-100%) and 100% specificity (93.5-100%) for detecting blaOXA-48-like genes from bacterial colonies. Its detection limit was 100 times less than that of the PCR method. This assay is rapid, easy to perform, and provides excellent performance without any special equipment. It may be applied for directly identifying the blaOXA-48-like genes in Enterobacterales obtained from blood culture. Rapid identification of carbapenemase types is essential for selecting appropriate antimicrobial options, particularly the ß-lactams combined with novel ß-lactamase inhibitors.
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Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), is an important bacterium that causes community and healthcare-related infections throughout the world. However, the current conventional detection methods are time-consuming. We therefore developed and evaluated a recombinase polymerase amplification-lateral flow strip (RPA-LF) approach for detection of MRSA in positive blood-culture samples. Sixty positive blood-cultures from a hospital were tested directly without DNA extraction and purification before the amplification reaction. RPA primers and probes were designed for nuc (encoding thermonuclease) and mecA (encoding penicillin-binding protein 2a) genes to diagnose S. aureus and its methicillin-resistance status. The RPA reaction occurred under isothermal conditions (45°C) within 20 min and a result was provided by the LF strip in a further 5 min at room temperature. The evaluation of RPA-LF using blood-culture samples showed 93.3% (14/15) sensitivity for identifying S. aureus, and no cross-amplification was seen [100% (45/45) specificity]. For detection of methicillin resistance, the RPA-LF test provided 100% (16/16) sensitivity and 97.7% (43/44) specificity. The RPA-LF is rapid, highly sensitive, robust and easy to use. It can be used for direct detection of MRSA with no requirement for special equipment.
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Staphylococcus aureus Resistente a Meticilina , Staphylococcus aureus Resistente a Meticilina/genética , Técnicas de Amplificación de Ácido Nucleico/métodos , Nucleotidiltransferasas , Recombinasas/genética , Sensibilidad y Especificidad , Staphylococcus aureus/genéticaRESUMEN
Carbapenemase-producing Gram-negative bacteria have been increasingly reported. Simple and sensitive methods for carbapenemase detection are still needed. In this study, a gold nanoparticle (AuNP) solution was modified by the addition of zinc sulfate (ZnSO4) for improving the conventional GoldNano Carb (cGoldC) test, and the modified GoldC (mGoldC) test was then evaluated for phenotypic detection of carbapenemase production in Gram-negative bacilli clinical isolates. ZnSO4 was added to give final concentrations of 0.25, 0.5, 0.75, and 1 mM. The performance of the mGoldC test was evaluated in Enterobacterales, Acinetobacter spp., and Pseudomonas aeruginosa isolates from six hospitals in different regions using polymerase chain reaction (PCR) as a gold standard. The AuNP solution with 0.25 mM ZnSO4 was used for the mGoldC test. Evaluation of the mGoldC test in 495 Enterobacterales, 212 Acinetobacter spp., and 125 P. aeruginosa isolates (including 444 carbapenemase producers and 388 non-carbapenemase producers) revealed sensitivity, specificity, a positive likelihood ratio, and a negative likelihood ratio of 98.6%, 98.2%, 54.7, and 0.01, respectively. This test is fast, easy to perform, cost-effective (~0.25 USD per test), and highly sensitive and specific for routine carbapenemase detection, thus leading to effective antimicrobial therapy and infection control measures.
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BACKGROUND: With limited information available, the association among urinary tract infections, urease-producing bacteria and the presence of magnesium ammonium phosphate (MAP) urolithiasis in canines in Thailand requires more study. OBJECTIVES: This study aimed to investigate the association between demographic characteristics of canines and the presence of MAP urolithiasis in canines, and to evaluate antimicrobial susceptibility patterns of bacteria isolated from canine uroliths. METHODS: A total of 56 canines admitted for treatment with surgical removal of uroliths were recruited. Demographic characteristics and clinical chemistry data were recorded. Bacteria isolated from the removed uroliths were identified. Chemical compositions of the uroliths were analyzed by Fourier transform infrared spectrometer. Potential risk factors were determined with univariable and multivariable logistic regression analyses. RESULTS: Of 56 canine urolithiasis, bacteria were isolated from uroliths of 38 canines (27 MAP and 11 non-MAP) but not from uroliths of 18 canines (5 MAP and 13 non-MAP). The most common bacteria found in nidus of MAP uroliths was Staphylococcus pseudintermedius (approximately 51%). An antimicrobial resistance was frequently found in Staphylococci isolates (42.86%). Multivariate logistic regression analysis showed that the predictors of MAP urolith in canine urolithiasis were being female (p = 0.044; adjusted odds ratio [OR], 10.22; 95% confidence interval [CI], 1.06-98.24) and the positive urolith culture (p = 0.012; adjusted OR, 8.60; 95% CI, 1.60-46.30). CONCLUSIONS: Our results indicate that S. pseudintermedius (a urease-producing bacterium) is the major causative bacteria of MAP uroliths. A positive urolith culture and being female are risk factors of MAP urolithiasis in canines.
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Infecciones Bacterianas , Enfermedades de los Perros , Cálculos Urinarios , Urolitiasis , Animales , Antiinfecciosos/farmacología , Bacterias , Infecciones Bacterianas/veterinaria , Perros , Farmacorresistencia Bacteriana , Femenino , Fosfatos , Factores de Riesgo , Estruvita , Ureasa , Cálculos Urinarios/veterinaria , Urolitiasis/veterinariaRESUMEN
OBJECTIVES: Treatment options are limited for melioidosis patients who develop nosocomial infections due to extensively drug-resistant (XDR) Gram-negative bacilli. Ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA), which have activity against XDR Gram-negative bacteria, are two potential options. Data regarding the susceptibility of Burkholderia pseudomallei to these agents are limited, especially from Thailand, which is an endemic area for melioidosis. METHODS: A total of 28 B. pseudomallei isolates from melioidosis patients in northeast Thailand were tested for susceptibility to C/T and CZA by Etest and the disk diffusion method. Minimum inhibitory concentrations (MICs) for other antibiotics commonly used in melioidosis, including trimethoprim/sulfamethoxazole (SXT), ceftazidime (CAZ), imipenem (IPM) and meropenem, were also determined. RESULTS: The MIC of C/T was very low for all isolates, ranging from 0.75 µg/mL to 1.0 µg/mL. For CZA, wide inhibitory zones ranging from 34-35 mm and MICs at 0.5 µg/mL were found. All isolates were also susceptible to SXT, CAZ and IPM based on Clinical and Laboratory Standards Institute (CLSI) breakpoints. CONCLUSION: C/T and CZA exhibited excellent in vitro activity against B. pseudomallei. Further studies are required to prove efficacy in human subjects.
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Burkholderia pseudomallei , Melioidosis , Compuestos de Azabiciclo , Ceftazidima/farmacología , Ceftazidima/uso terapéutico , Cefalosporinas , Humanos , Melioidosis/tratamiento farmacológico , Pseudomonas aeruginosa , Tazobactam/farmacología , TailandiaRESUMEN
Vancomycin-resistant enterococci (VRE), especially Enterococcus faecium, have been a global concern, often causing serious healthcare-associated infections. We established a rapid approach for detecting E. faecium and vancomycin-resistance genes (vanA and vanB) in clinical samples using isothermal recombinase polymerase amplification (RPA) combined with a lateral-flow (LF) strip. Specific RPA primer sets and probes for ddl (to identify the presence of E. faecium) vanA and vanB genes were designed. The RPA reaction was performed under isothermal condition at 37 °C within 20 min and read using the LF strip within a further 5 min. A total of 141 positive blood-cultures and 136 stool/rectal swab samples were tested using RPA-LF method compared to the conventional PCR method. The RPA-LF method exhibited 100% sensitivity in both blood-culture (60 E. faecium; 35 vanA type and two vanB type) and stool/rectal-swab samples (63 E. faecium and 36 vanA type) without cross-reaction (100% specificity). The lower detection limit of the RPA-LF was approximately 10 times better than that of the conventional PCR method. The RPA-LF method is an alternative rapid method with excellent sensitivity and specificity for detecting E. faecium, vanA, and vanB, and it has the potential to be used as a point-of-care device for VRE therapy and prevention.
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Lung granulomas are uncommon in Thailand. The disease typically develops from an occupational environment and is mostly caused by infection. Herein is a case report of a female patient, aged 48, working as a nurse in an Accident and Emergency Department at a hospital. Eighteen years prior to admission the patient was diagnosed with myasthenia gravis and pulmonary tuberculosis. The chest X-ray and CT scans showed a solitary pulmonary nodule in the lower left lung. The patient received an open thoracotomy with a left lobectomy. Granulomatous and nonseptate hyphae were found in the pathology diagnosis. The patient was thus diagnosed as having a lung granuloma. The galactomannan antigen test was positive. The solitary pulmonary nodule-found from the use of a Polymerase Chain Reaction (PCR) test-was an Aspergillus spp. The fungus culture was collected from air samples. The air samples were collected by the impaction technique using a microbial air sampler. Three types of Aspergillus spp. were found as well as Penicillium spp. and Monilia sitophila. The Aspergillus spp. was a match for the patient's disease. The patient was diagnosed as having a lung granuloma possibly Aspergillus nodule which was caused by airborne Aspergillus spp. from the occupational environment.
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The global emergence of colistin resistance in carbapenem-resistant Acinetobacter baumannii (CRAB) clinical isolates is a serious public health concern. We therefore aimed to investigate colistin resistance mechanisms in 5 colistin-resistant (COL-R) CRAB isolates collected from Thai patients in 2016 by whole genome sequencing (WGS) compared with those of 5 colistin-intermediate (COL-I) CRAB isolates from the same period. All isolates were subjected to antimicrobial susceptibility testing, efflux pump inhibitor-based test and WGS. Mutations in known genes associated with colistin resistance were analyzed and deleterious mutations were then predicted by PROVEAN tool. The 10 CRAB isolates carried blaOXA-23 with the addition of blaOXA-58 in 1 isolate. All COL-R isolates exhibited colistin MICs of 4 µg/mL except for 1 isolate with that of 16 µg/mL. They belonged to ST2, ST16, ST23, ST164 and ST215, whereas the COL-I isolates with colistin MICs of ≤0.25-1 µg/mL were ST2, ST164 and ST215. Neither increased efflux pump activity nor mcr gene was found in any COL-R isolate. Three COL-R isolates contained different PmrB variants: a novel 10-amino acid (aa) repeat sequence insertion, VILGCILIFS between positions 27 and 28 (S27_A28insVILGCILIFS) in transmembrane domain (TM); a 1-aa insertion, alanine between positions 162 and 163 (A162_I163insA) in TM; and a 1-aa substitution, A226T in histidine kinase domain. One COL-R isolate possessed PmrA variant with A80V substitution. These alterations were predicted as deleterious. Mechanisms of colistin resistance in the remaining COL-R isolate were still unknown. In conclusion, the alterations in both PmrB and PmrA were predicted and suggested as initial mutations responsible for low-level colistin resistance in our CRAB isolates. Under selective pressure, these isolates may exhibit higher level colistin resistance by the additional mutations, leading to more therapeutic difficulties.
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Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/genética , Proteínas Bacterianas/genética , Carbapenémicos/farmacología , Colistina/farmacología , Farmacorresistencia Bacteriana , Mutagénesis Insercional , Factores de Transcripción/genética , Infecciones por Acinetobacter/tratamiento farmacológico , Antibacterianos/farmacología , Proteínas Bacterianas/química , Genoma Bacteriano , Genómica , Pruebas de Sensibilidad Microbiana , Factores de Transcripción/químicaRESUMEN
Bloodstream infection (BSI) is a major cause of mortality in hospitalized patients worldwide. Staphylococcus aureus is one of the most common pathogens found in BSI. The conventional workflow is time consuming. Therefore, we developed a lateral flow immunoassay (LFIA) for rapid detection of S. aureus-protein A in positive blood culture samples. A total of 90 clinical isolates including 58 S. aureus and 32 non-S. aureus were spiked in simulated blood samples. The antigens were extracted by a simple boiling method and diluted before being tested using the developed LFIA strips. The results were readable by naked eye within 15 min. The sensitivity of the developed LFIA was 87.9% (51/58) and the specificity was 93.8% (30/32). When bacterial colonies were used in the test, the LFIA provided higher sensitivity and specificity (94.8% and 100%, respectively). The detection limit of the LFIA was 107 CFU/mL. Initial evaluation of the LFIA in 20 positive blood culture bottles from hospitals showed 95% agreement with the routine methods. The LFIA is a rapid, simple and highly sensitive method. No sophisticated equipment is required. It has potential for routine detection particularly in low resource settings, contributing an early diagnosis that facilitates effective treatment and reduces disease progression.
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Methicillin-resistant staphylococci (MRS) are important antimicrobial-resistant pathogens in sepsis. Conventional blood cultures take 24-72 h. The polymerase chain reaction (PCR)-based methods give faster results (2-3 h) but need expensive thermal cyclers. We therefore developed an isothermal recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD) assay for rapid detection of MRS in spiked blood culture samples. Fifty-six clinical isolates including 38 mecA-carrying staphylococci and 18 non-mecA-carrying organisms as confirmed by PCR methods were studied. RPA primer set and probe specific for mecA gene (encoding penicillin-binding protein 2a) were designed. RPA reaction was carried out under isothermal condition (45 °C) within 20 min and read by LFD in 5 min. The RPA-LFD provided 92.1% (35/38) sensitivity for identifying MRS in positive blood culture samples, and no cross-amplification was found (100% specificity). This test failed to detect three mecA-carrying S.sciuri isolates. The detection limits of RPA-LFD method for identifying MRS were equal to those of PCR method. The RPA-LFD is simple, fast, and user-friendly. This method could detect the mecA gene directly from the positive blood culture samples without requirement for special equipment. This method would be useful for appropriate antibiotic therapy and infection control, particularly in a low-resource setting.
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Farmacorresistencia Bacteriana , Staphylococcus/efectos de los fármacos , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Cultivo de Sangre , ADN Bacteriano/genética , ADN Bacteriano/aislamiento & purificación , Técnicas de Amplificación de Ácido Nucleico , Proteínas de Unión a las Penicilinas/genética , Proteínas de Unión a las Penicilinas/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Sensibilidad y Especificidad , Staphylococcus/clasificación , Staphylococcus/metabolismoRESUMEN
Staphylococcus aureus strains resistant to the last line antibiotic, vancomycin, have been of clinical concern. These include heterogeneous vancomycin-intermediate S. aureus (hVISA) and VISA. The hVISA phenotype cannot be detected by routine laboratory methods. Characterization of hVISA/VISA by new technologies is necessary to differentiate them rapidly from the vancomycin-susceptible isolates (VSSA). In this study, we developed a model for discrimination of hVISA from VSSA by using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy combined with multivariate data analysis, displaying a phenotypic signature of the bacteria. ATR-FTIR spectra were acquired from a total of 59 clinical methicillin-resistant S. aureus (MRSA) isolates comprising 28 hVISA and 31 VSSA strains. Principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) were used to analyze 351 spectra of 39 isolates and develop a discrimination model for identifying hVISA and VSSA. The classification model, which was used for blind testing of 90 spectra from each of 10 hVISA, and 10 VSSA isolates, provided 100% sensitivity and specificity. The modeling revealed that the major discrimination between hVISA and VSSA phenotypes involved bands related to cell wall content (1087 and 1057 cm-1). This study showed that ATR-FTIR technique may be an alternative method for rapid detection of low-level vancomycin-resistant S. aureus.
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Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Vancomicina/farmacología , Análisis de los Mínimos Cuadrados , Pruebas de Sensibilidad Microbiana , Fenotipo , Análisis de Componente Principal , Espectroscopía Infrarroja por Transformada de Fourier , Resistencia a la VancomicinaRESUMEN
Sepsis is a condition that requires appropriate antibiotic treatment at the emergency department (ED). Most previous studies conducted on inappropriate antibiotic use at the ED were conducted in developed countries with a low percentage of sepsis. This study aimed to find additional clinical predictors for appropriate antibiotic use in bacteremia patients presenting at the ED from a developing country, in which there is a higher proportion of patients with sepsis. We included adult patients who presented at the ED with clinical suspicion of infection and bacteremia. Patients allocated to the appropriate antibiotic group were those in whom the prescribed antibiotic was sensitive to the pathogen. Predictors and outcomes of appropriate antibiotic use were analyzed. A total of 3133 patients who met the study criteria presented at the ED during the study period. Of those, 271 patients were diagnosed with bacteremia, 48 of whom (17.71%) received inappropriate antibiotic prescriptions. Only pulse rate was an independent factor for appropriate antibiotic treatment, with an adjusted odds ratio of 1.019 (95% CI of 1.001, 1.036). In terms of clinical outcomes, the inappropriate antibiotic group had higher proportions of 28-day mortality (29.17% vs. 25.25%; p-value = 0.022) and longer hospitalization (14 vs. 9 days; p-value = 0.003). This study found that inappropriate antibiotics were prescribed in 17% of bacteremia patients presenting at the ED and that high pulse rate was an indicator for appropriate antibiotic prescription. Patients with inappropriate antibiotic administration had longer hospitalization and higher 28-day mortality than those who received appropriate antibiotic treatment.
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Twelve nonreplicate carbapenemase-negative ertapenem (ETP)-nonsusceptible (CNENS) Escherichia coli isolates obtained at a Thai university hospital between 2010 and 2014 were characterized and compared with 2 carbapenemase-producing E. coli isolates from the same hospital. Eight unique pulsed-field gel electrophoresis patterns were obtained. All the isolates produced CTX-M-15 ß-lactamase and 2 either coexpressed CMY-2 cephalosporinase or showed increased efflux pump activity. Amino acid sequence analysis revealed that an OmpF defect (in 7 isolates) due to mutations generating truncated proteins or an IS1 insertion was more prevalent than a defect in OmpC was (no truncated proteins detected). Seven out of 10 isolates possessing OmpC variants with any OmpF defect were weakly ETP-resistant (minimum inhibitory concentrations [MICs] of 1-4 µg/mL) and imipenem (IPM)- and meropenem (MEM)-susceptible (MICs 0.125-0.5 µg/mL). Two isolates with ompC PCR-negative results and an OmpF defect showed higher carbapenem MICs (8-32, 1-8, and 1-4 µg/mL for ETP, IPM, and MEM, respectively) with the highest MICs associated with the additional efflux pump activity. Both carbapenemase producers possessing CTX-M-15 and a porin background identical to that in the CNENS isolates showed ETP, IPM, and MEM MICs of 128-256, 8, and 2-32 µg/mL, respectively. These findings suggest that a porin defect combined with CTX-M-15 production is the major mechanism of low carbapenem susceptibility among our CNENS isolates, which have potential to become strongly carbapenem-resistant because of additional carbapenemase or efflux pump activities.
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Proteínas Bacterianas/genética , Infección Hospitalaria , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/microbiología , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Hospitales Universitarios , beta-Lactamasas/genética , Secuencia de Aminoácidos , Antibacterianos/farmacología , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/química , Análisis por Conglomerados , Escherichia coli/clasificación , Escherichia coli/aislamiento & purificación , Humanos , Pruebas de Sensibilidad Microbiana , Tipificación Molecular , Porinas/genética , Tailandia/epidemiología , beta-Lactamasas/biosíntesis , beta-Lactamasas/químicaRESUMEN
Carbapenem-resistant Enterobacteriaceae isolates by carbapenemase production are being reported globally with increasing frequency, leading to limited therapeutic options. We therefore developed a loop-mediated isothermal amplification method with hydroxynaphthol blue dye (LAMP-HNB) for rapid confirmation of bla NDM, bla OXA-48, bla VIM, bla IMP-14 and bla KPC groups. Sixty-two Enterobacteriaceae and Pseudomonas spp. isolates carrying various carbapenemase genes (28 bla NDM-1, 9 bla IMP-14a, 2 bla IMP-48, 1 bla IMP-1, 1 bla IMP-4, 1 bla IMP-9, 1 bla IMP-15, 4 bla VIM-2, 1 bla VIM-1, 1 bla IMP-14a & bla VIM-2, 7 bla KPC-2, 3 bla OXA-48 and 3 bla OXA-181) and 37 non-carbapenemase-producing Enterobacteriaceae isolates as confirmed by the PCR methods were included. Bacterial DNA was extracted by a simple boiling method. The LAMP-HNB method for each target gene was carried out using a set of six primers under isothermal condition at 65 °C in an ordinary water bath within 60 min and visual measurement of reaction by the change from violet to sky blue. This method had high efficiency (100% sensitivity and specificity) for identifying the bla NDM, bla OXA-48, bla VIM, bla IMP-14 and bla KPC groups compared with the PCR method. The HNB is easy to prepare, inexpensive and provides reliable results. Therefore, this method could be used as a confirmatory carbapenemase test in routine laboratory or for epidemiological purposes.