Variability of antibiograms: how often do changes in the antimicrobial susceptibility pattern occur in isolates from one patient?

ObjectivesMany laboratories do not perform antimicrobial susceptibility testing (AST) for all consecutive isolates of the same species from one patient. The objective of this study was to assess how often changes in antimicrobial susceptibility patterns (cASP) occur in such isolates.MethodsAST was performed for all isolates of defined species obtained from clinical routine (2015–2018) without restrictions for consecutive or sequential isolates of one patient. Occurrence of cASP and time between the first sampling date and first cASP were determined by combining antibiograms from all specimens and after stratification into species and specimens.ResultsA total of 35 473 AST results were included (range 2–71 per case). Combining pathogens and specimens, 1991 cASP occurred in 1269/8502 (14.9%) of all cases after a median time until cASP of 5 days (range 0–364). Of these, 628/1991 (31.5%) occurred on the day of first sampling (predominantly due to phenotypic variants in the same specimen). Excluding isolates with differing AST pattern on the first day of sampling, the median time until cASP was 12 days (range 1–364). Stratification into species and specimen revealed a large variance of the median time until cASP (e.g. in Escherichia coli: 5 days; range 1–48 for blood cultures or 16 days; 1–364 for urine).DiscussionUsing routine microbiological data in a large tertiary hospital, cASP occurs occasionally. The time to perform subsequent AST to detect cASP depends on the species and type of specimen. Other studies are needed to evaluate whether ideal time intervals applicable beyond local settings can be defined.     

Isothermal microcalorimetry minimal inhibitory concentration testing in extensively drug resistant Gram-negative bacilli: a multicentre study

ObjectivesTo evaluate the performance of an isothermal microcalorimetry (IMC) method for determining the MICs among extensively drug-resistant Gram-negative bacilli.MethodsA collection of 320 clinical isolates (n = 80 of each) of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii from Sweden, Spain, Italy and the Netherlands were tested. The MICs were determined using the IMC device calScreener (Symcel, Stockholm, Sweden) and ISO-broth microdilution as the reference method. Essential agreement, categorical agreement, very major errors (VME), major errors (ME) and minor (mE) errors for each antibiotic were determined.ResultsData from 316 isolates were evaluated. Four errors (two ME, one VME, one mE) among 80 K. pneumoniae, six errors (four ME, one VME, one mE) among 79 E. coli, 15 errors (seven VME, three ME, five mE) among 77 P. aeruginosa and 18 errors (12 VME, two ME, four mE) among 80 A. baumannii were observed. Average essential agreement and categorical agreement of the IMC method were 96.6% (95% confidence interval, 94.2–99) and 97.1% (95% confidence interval, 95.4–98.5) respectively when the MICs were determined at the end of 18 hours. Categorical agreement of the IMC method for prediction of MIC by the end of 8 hours for colistin, meropenem, amikacin, ciprofloxacin and piperacillin/tazobactam were 95%, 91.4%, 94%, 95.2% and 93.7% respectively.ConclusionsThe IMC method could accurately determine the MICs among extensively drug-resistant clinical isolates of E. coli, K. pneumoniae, P. aeruginosa and A. baumannii isolates.     

Enhanced antimicrobial stewardship based on rapid phenotypic antimicrobial susceptibility testing for bacteraemia in patients with haematological malignancies: a randomized controlled trial

ObjectivesRecently, rapid phenotypic antimicrobial susceptibility testing (AST) based on microscopic imaging analysis has been developed. The aim of this study was to determine whether implementation of antimicrobial stewardship programmes (ASP) based on rapid phenotypic AST can increase the proportion of patients with haematological malignancies who receive optimal targeted antibiotics during early periods of bacteraemia.MethodsThis randomized controlled trial enrolled patients with haematological malignancies and at least one positive blood culture. Patients were randomly assigned 1:1 to conventional (n = 60) or rapid phenotypic (n = 56) AST. The primary outcome was the proportion of patients receiving optimal targeted antibiotics 72 hr after blood collection for culture.ResultsThe percentage receiving optimal targeted antibiotics at 72 hr was significantly higher in the rapid phenotypic AST group (45/56, 80.4%) than in conventional AST group (34/60, 56.7%) (relative risk (RR) 1.42, 95% confidence interval (CI) 1.09–1.83). The percentage receiving unnecessary broad-spectrum antibiotics at 72 hr was significantly lower (7/26, 12.5% vs 18/60, 30.0%; RR 0.42, 95% CI 0.19–0.92) and the mean time to optimal targeted antibiotic treatment was significantly shorter (38.1, standard deviation (SD) 38.2 vs 72.8, SD 93.0 hr; p < 0.001) in the rapid phenotypic AST group. The mean time from blood collection to the AST result was significantly shorter in the rapid phenotypic AST group (48.3, SD 17.6 vs 83.1, SD 22.2 hr).DiscussionASP based on rapid phenotypic AST can rapidly optimize antibiotic treatment for bacteraemia in patients with haematological malignancy. Rapid phenotypic AST can improve antimicrobial stewardship in immunocompromised patients.     

Prognostic value of microRNA-451 in various cancers: A meta-analysis

BackgroundIncreasing evidence shows microRNA-451 plays a crucial role in various tumors, but there is inconsistency. The aim of this study was to explore the prognostic role of miR-451 in various tumors.MethodsOnline PubMed, EMBASE, Web of Science, and the Cochrane library database were searched through February 2019. Hazard ratios (HRs) were extracted and used to describe the association between expression of microRNA-451 and survival outcome, and the correlation between microRNA-451 and clinicopathologic features were described by pooled odds ratios (ORs).ResultsSixteen retrospective studies containing 2122 patients were incorporated in this meta-analysis. High expression of miR-451 was considered statistically associated with prolonged overall survival (OS) (HR = 0.62, 95% CI 0.49-0.80, p < 0.001) as well as RFS/DFS (HR = 0.55, 95% CI 0.42-0.71, p < 0.001) compared with low expression of miR-451. Besides, the pooled ORs revealed significant association between high expression of miR-451 with lymph node invasion (yes vs. no) (OR = 0.64, 95% CI 0.46-0.90, P = 0.01), tumor diameter (big vs. small) (OR = 0.77, 95% CI 0.60-0.97, P = 0.028) and tumor stage (III + IV vs. I + II) (OR = 0.62, 95% CI 0.42-0.93, P = 0.019).ConclusionMicroRNA-451 may serve as a promising clinical prognostic biomarker in various carcinomas.     

Automatically finding relevant citations for clinical guideline development

ObjectiveLiterature database search is a crucial step in the development of clinical practice guidelines and systematic reviews. In the age of information technology, the process of literature search is still conducted manually, therefore it is costly, slow and subject to human errors. In this research, we sought to improve the traditional search approach using innovative query expansion and citation ranking approaches.MethodsWe developed a citation retrieval system composed of query expansion and citation ranking methods. The methods are unsupervised and easily integrated over the PubMed search engine. To validate the system, we developed a gold standard consisting of citations that were systematically searched and screened to support the development of cardiovascular clinical practice guidelines. The expansion and ranking methods were evaluated separately and compared with baseline approaches.ResultsCompared with the baseline PubMed expansion, the query expansion algorithm improved recall (80.2% vs. 51.5%) with small loss on precision (0.4% vs. 0.6%). The algorithm could find all citations used to support a larger number of guideline recommendations than the baseline approach (64.5% vs. 37.2%, p < 0.001). In addition, the citation ranking approach performed better than PubMed’s “most recent” ranking (average precision +6.5%, recall@k +21.1%, p < 0.001), PubMed’s rank by “relevance” (average precision +6.1%, recall@k +14.8%, p < 0.001), and the machine learning classifier that identifies scientifically sound studies from MEDLINE citations (average precision +4.9%, recall@k +4.2%, p < 0.001).ConclusionsOur unsupervised query expansion and ranking techniques are more flexible and effective than PubMed’s default search engine behavior and the machine learning classifier. Automated citation finding is promising to augment the traditional literature search.     

Incidence of speech recognition errors in the emergency department

BackgroundPhysician use of computerized speech recognition (SR) technology has risen in recent years due to its ease of use and efficiency at the point of care. However, error rates between 10 and 23% have been observed, raising concern about the number of errors being entered into the permanent medical record, their impact on quality of care and medical liability that may arise. Our aim was to determine the incidence and types of SR errors introduced by this technology in the emergency department (ED).SettingLevel 1 emergency department with 42,000 visits/year in a tertiary academic teaching hospital.MethodsA random sample of 100 notes dictated by attending emergency physicians (EPs) using SR software was collected from the ED electronic health record between January and June 2012. Two board-certified EPs annotated the notes and conducted error analysis independently. An existing classification schema was adopted to classify errors into eight errors types. Critical errors deemed to potentially impact patient care were identified.ResultsThere were 128 errors in total or 1.3 errors per note, and 14.8% (n = 19) errors were judged to be critical. 71% of notes contained errors, and 15% contained one or more critical errors. Annunciation errors were the highest at 53.9% (n = 69), followed by deletions at 18.0% (n = 23) and added words at 11.7% (n = 15). Nonsense errors, homonyms and spelling errors were present in 10.9% (n = 14), 4.7% (n = 6), and 0.8% (n = 1) of notes, respectively. There were no suffix or dictionary errors. Inter-annotator agreement was 97.8%.ConclusionsThis is the first estimate at classifying speech recognition errors in dictated emergency department notes. Speech recognition errors occur commonly with annunciation errors being the most frequent. Error rates were comparable if not lower than previous studies. 15% of errors were deemed critical, potentially leading to miscommunication that could affect patient care.     

From genotype to antibiotic susceptibility phenotype in the order Enterobacterales: a clinical perspective

ObjectivesPredicting the antibiotic susceptibility phenotype from genomic data is challenging, especially for some specific antibiotics in the order Enterobacterales. Here we aimed to assess the performance of whole genomic sequencing (WGS) for predicting the antibiotic susceptibility in various Enterobacterales species using the detection of antibiotic resistance genes (ARGs), specific mutations and a knowledge-based decision algorithm.MethodsWe sequenced (Illumina MiSeq, 2×250 bp) 187 clinical isolates from species possessing (n = 98) or not (n = 89) an intrinsic AmpC-type cephalosporinase. Phenotypic antibiotic susceptibility was performed by the disc diffusion method. Reads were assembled by A5-miseq and ARGs were identified from the ResFinder database using Diamond. Mutations on GyrA and ParC topoisomerases were studied. Piperacillin, piperacillin-tazobactam, ceftazidime, cefepime, meropenem, amikacin, gentamicin and ciprofloxacin were considered for prediction.ResultsA total of 1496 isolate/antibiotic combinations (187 isolates × 8 antibiotics) were considered. In 230 cases (15.4%), no attempt of prediction was made because it could not be supported by current knowledge. Among the 1266 attempts, 1220 (96.4%) were correct (963 for predicting susceptibility and 257 for predicting resistance), 24 (1.9%) were major errors (MEs) and 22 (1.7%) were very major errors (VMEs). Concordance were similar between non-AmpC and AmpC-producing Enterobacterales (754/784 (96.2%) vs 466/482 (96.7%), chi-square test p 0.15), but more VMEs were observed in non-AmpC producing strains than in those producing an AmpC (19/784 (2.4%) vs 3/466 (0.6%), chi-square test p 0.02). The majority of VMEs were putatively due to the overexpression of chromosomal genes.ConclusionsIn conclusion, the inference of antibiotic susceptibility from genomic data showed good performances for non-AmpC and AmpC-producing Enterobacterales species. However, more knowledge about the mechanisms underlying the derepression of AmpC are needed.     

Evaluation of sulbactam and colistin/sulbactam efficacy against multiple resistant Acinetobacter baumannii blood isolates

PurposeWe aimed to compare the results of the BD Phoenix (TM) M50 ID/AST system and the gold standard broth microdilution method. We also evaluated the potential of a new therapeutic combination (colistin/sulbactam) for colistin resistance among Acinetobacter baumanni strains.MethodsGrowth in blood samples was detected with the BACTEC (BD Becton Dickinson, ABD) continuous monitoring blood culture system. Strains were identified by Phoenix (BD Phoenix? M50, ABD) automated bacterial identification system and antimicrobial susceptibility results were obtained. A total of 92 A. baumannii complex isolates showing resistance to at least three antibiotic classes were included in the study. Colistin susceptibility results (both susceptible and resistant strains) detected by the Phoenix device were confirmed by the reference method, the liquid microdilution method. The concentration index (FIC) was used to determine the efficacy of fractional inhibitor drug combinations, the efficacy of colistin/sulbactam combination against 50 multiresistant A. baumannii complex strains was investigated using the checkerboard method.Results10 (10.9%) of 92 isolates were resistant to colistin and 80 (86.9%) to sulbactam. With the automation system, only 2 of 10 isolates were found resistant to colistin, while 8 isolates were susceptible. For this reason, the very major error rate of the Phoenix M50 automatic system among resistant isolates was determined as 8/10. It was determined that 6 (12%) of the colistin/sulbactam combination had a synergistic effect and 44 (88%) had an additive interaction. No antagonistic interaction was detected with the colistin–sulbactam combination in this study.ConclusionA. baumannii strains should be confirmed by the broth microdilution method, which is the reference method, against the MIC results detected by automated systems. It was concluded that the use of colistin alone should be avoided in the treatment of A. baumannii infections.     

Performance evaluation of the Becton Dickinson Kiestra™ IdentifA/SusceptA

ObjectivesNew automated modules are required to provide fully automated solutions in diagnostic microbiology laboratories. We evaluated the performance of a Becton Dickinson Kiestra™ IdentifA/SusceptA prototype for MALDI-TOF identification (ID) and Phoenix™ antibiotic susceptibility testing (AST).MethodsThe performance of the IdentifA/SusceptA coupled prototype was compared with manual processing for MALDI-TOF ID on 1302 clinical microbial isolates or ATCC strains and for Phoenix™ M50 AST on 484 strains, representing 61 species.ResultsOverall, the IdentifA exhibited similar ID performances than manual spotting. Higher performances were observed for Gram-negative bacteria with an ID at the species level (score >2) of 96.5% (369/382) and 86.9% (334/384), respectively. A significantly better performance was observed with the IdentifA (95.2%, 81/85) compared with manual spotting (75.2%, 64/85) from colonies on MacConkey agar. Contrariwise, the IdentifA exhibited lower ID performances at the species level than manual processing for streptococci (76.1%, 96/126 compared with 92%, 115/125), coagulase-negative staphylococci (73.3%, 44/60 compared with 90%, 54/60) and yeasts (41.3%, 19/46 compared with 78.2%, 36/46). Staphylococcus aureus and enterococci were similarly identified by the two approaches, with ID rates of 92% (65/70) for the IdentifA and 92.7%, (64/69) for manual processing and 94.8%, (55/58) for the IdentifA and 98.2%, (57/58) for manual processing, respectively. The SusceptA exhibited an AST overall essential agreement of 98.82% (6863/6945), a category agreement of 98.86% (6866/6945), 1.05% (6/570) very major errors, 0.16% (10/6290) major errors, and 0.91% (63/6945) minor errors compared to the reference AST.ConclusionsOverall, the automated IdentifA/SusceptA exhibited high ID and AST performances.     

Validation of Vitek 2 Nonfermenting Gram-Negative Cards and Vitek 2 Version 4.02 Software for Identification and Antimicrobial Susceptibility Testing of Nonfermenting Gram-Negative Rods from Patients with Cystic Fibrosis

Accurate identification and antimicrobial susceptibility testing (AST) of nonfermenters from cystic fibrosis patients are essential for appropriate antimicrobial treatment. This study examined the ability of the newly designed Vitek 2 nonfermenting gram-negative card (NGNC) (new gram-negative identification card; bioMérieux, Marcy-l''Ètoile, France) to identify nonfermenting gram-negative rods from cystic fibrosis patients in comparison to reference methods and the accuracy of the new Vitek 2 version 4.02 software for AST compared to the broth microdilution method. Two hundred twenty-four strains for identification and 138 strains for AST were investigated. The Vitek 2 NGNC identified 211 (94.1%) of the nonfermenters correctly. Among morphologically atypical microorganisms, five strains were misidentified and eight strains were determined with low discrimination, requiring additional tests which raised the correct identification rate to 97.8%. Regarding AST, the overall essential agreement of Vitek 2 was 97.6%, and the overall categorical agreement was 92.9%. Minor errors were found in 5.1% of strains, and major and very major errors were found in 1.6% and 0.3% of strains, respectively. In conclusion, the Vitek NGNC appears to be a reliable method for identification of morphologically typical nonfermenters and is an improvement over the API NE system and the Vitek 2 GNC database version 4.01. However, classification in morphologically atypical nonfermenters must be interpreted with care to avoid misidentification. Moreover, the new Vitek 2 version 4.02 software showed good results for AST and is suitable for routine clinical use. More work is needed for the reliable testing of strains whose MICs are close to the breakpoints.Pseudomonas aeruginosa is the most important cause of lung infections in patients with cystic fibrosis (CF) (14). In our hospital, 50% of sputum-producing CF patients are colonized in their lower airways with P. aeruginosa or other nonfermenting bacteria. Accurate identification and antimicrobial susceptibility testing (AST) are essential for appropriate antimicrobial therapy.A variety of automated commercial systems for identification and susceptibility testing of nonfermenting bacteria are available (2, 3, 12, 19, 20). They are widely used because of the increasing volumes of clinical specimens processed by clinical laboratories and perceived cost effectiveness. The automated systems decrease the in-laboratory turnaround time and enable a faster targeted antimicrobial therapy. Unfortunately, errors in classification and AST by any test system can have serious implications for the clinical outcome of patients. The most frequently reported errors have involved the inaccurate identification of nonfermenters due to their phenotypic variations and slower growth rates and the inconsistencies between the tested broad-spectrum β-lactam antibiotics. Because of the perceived inaccuracies of AST from CF isolates, a consensus conference on CF microbiology recommended the use of the disk diffusion method for testing P. aeruginosa and other nonfermenters (13, 22).To improve the identification rate of nonfermenting gram-negative bacilli, a new colorimetric Vitek 2 card (nonfermenting gram-negative card [NGNC]) with an enlarged database was recently introduced. To advance the accuracy of the AST results, a new software (version 4.02) was developed.The aim of the present study was to evaluate the performance of the new NGNC for identification and the new software version 4.02 for AST of nonfermenters isolated from CF patients.     

Caspase-cleaved fragments of cytokeratin-18 as a marker of inflammatory activity in chronic hepatitis B virus infection

BackgroundThe differential diagnosis between inactive carrier and active hepatitis is important in patients with chronic hepatitis B (CHB) virus infection. Serum cytokeratin (CK)-18 fragments (M30-antigen) are proposed as biomarkers of apoptosis.ObjectivesWe investigated whether serum M30-antigen levels might help to characterize the various phases of CHB and predict the state of significant inflammation in patients with CHB.Study designA total of 339 CHB patients who underwent liver biopsy, were included. Serum M30-antigen levels were compared between inactive carriers (n = 21), patients with HBeAg-negative hepatitis (n = 95), HBeAg-positive hepatitis (n = 141) and liver cirrhosis (n = 82).ResultsSerum M30-antigen levels were correlated significantly not only with AST (r = 0.544, p < 0.001) and ALT (r = 0.315, p < 0.001) and but also inflammatory grading score on liver biopsy (r = 0.240, p < 0.001). Serum M30-antigen level in HBeAg-negative CHB was significantly higher than that of inactive HBV carrier (399.78 U/L vs 148.90 U/L, p < 0.001). Multivariate analysis showed that AST (p < 0.001), albumin (p = 0.009) and M30-antigen (p = 0.020) were the independent predictors of significant inflammation. Combined serum M30-antigen level (>344 U/L) and AST (>78 IU/L) measurement provided the most accurate identification of significant inflammation, showing 38.2% sensitivity, 96.1% specificity, 91.0% positive predictive value and 56.1% negative predictive value.ConclusionsSerum M30-antigen can be a predictive marker for distinguishing between inactive carrier and HBeAg-negative CHB. Serum M30 levels are associated with the presence of significant inflammation, especially in patients with normal or minimally elevated ALT in CHB patients.     

The impact of medical informatics on patient satisfaction: A USA-based literature review

PurposePatient satisfaction is increasingly recognized as an important component of quality. The expansion of health information technologies (HIT) might have an impact on patient satisfaction – either positively or negatively. We conducted a literature review to explore the impact of these technologies on patient satisfaction.MethodsThe database of PubMed was searched from inception through May 2010, using the MeSH terms “Medical Informatics” and “Patient Satisfaction”. We included all original interventional studies regardless of their study design that were published in English and were evaluating HIT impact on patient satisfaction. Studies were categorized by technology type according to the American Medical Informatics Association framework and by study design. The major outcome of interest was the HIT impact on patient satisfaction.ResultsOf 1293 citations reviewed, 56 studies met our inclusion criteria. Design of these studies included mostly randomized controlled trials (RCTs) (n = 20, 36%), cross-sectional surveys (n = 17, 30%), and a pre and post studies (n = 14, 25%). Overall, 54% (n = 30) of the studies demonstrated a positive effect of HIT on patient satisfaction, 34% (n = 19) failed to show any effect, 11% (n = 6) had inconclusive results, and 2% (n = 1) revealed a negative effect. Of the 20 RCTs, 40% (n = 8) showed a positive effect of HIT on patient satisfaction, 50% (n = 10) failed to show any effect, and 10% (2) had inconclusive results.ConclusionsAnalysis suggested that while there is some evidence that HIT improves patient satisfaction, studies in this literature review, and in particularly RCTs, were not consistent in their findings. Although HIT may be a promising tool to improve patient satisfaction, more well-designed research studies are needed in order to get a better understanding of this domain and accordingly find new opportunities to improve quality of care.     

Glycogenic hepatopathy is associated with type 1 diabetes mellitus in only a minority of cases in a contemporary adult population

ObjectivesThis study examines the clinical-pathological profiles of patients with glycogenic hepatopathy in a contemporary cohort of patients at an adult acute care hospital.MethodsLiver biopsies with glycogenic hepatopathy were retrieved from the departmental surgical pathology database, the histological findings were studied, and the clinical findings were reviewed.ResultsFive cases of glycogenic hepatopathy were found, including cases associated with type 1 diabetes mellitus (n = 1), type 2 diabetes mellitus (n = 1), corticosteroids (n = 2), and anorexia (n = 2, including the patient with type 1 diabetes). AST and ALT were normal to mildly elevated (13–115 U/L and 7–126 U/L, respectively). Trace ascites was present in two patients. Hepatomegaly was only present in the patient with type 1 diabetes at the time of diagnosis.ConclusionsFour of five cases were associated with etiologies other than type 1 diabetes, which is widely reported as the most common etiology of glycogenic hepatopathy. This study suggests that etiologies currently only rarely recognized may actually be more common causes of glycogenic hepatopathy than type 1 diabetes in a contemporary adult population. It is important not only to recognize that these rarely reported causes of glycogenic hepatopathy may be underrecognized, but that the clinical presentation may also be mild.     

Hepcidin-to-ferritin ratio: A potential novel index to predict iron overload-liver fibrosis in ß-thalassemia major

ObjectivesWe aimed to determine a threshold cutoff for hepcidin, ferritin, and the hepcidin-to-ferritin ratio in the diagnosis of liver fibrosis caused by iron overload in chronic hepatitis C virus (HCV)-free ß-thalassemia major patients .MethodsThis 1:1-matched case-control study included 102 individuals (3–30 yr.); 51 ß-thalassemia major patients with iron overload , and 51 apparently healthy individuals.ResultsThe highest areas under the receiver operating characteristic curves (AUC-ROCs) for the diagnosis of patients vs. controls had overlapping 95% confidence intervals (CIs): serum hepcidin (0.758; 0.64–0.87;    P ? 0.001), serum ferritin (1.000; 1.00–1.00; P  ?0.001), and the hepcidin/ferritin ratio (1.000; 1.00–1.00; P ? 0.001). For differentiation of patients with liver fibrosis stages of F0–F1 vs. F2–F4 and F0–F1 vs. F3–F4, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) with P-values ? 0.001 were the only statistically significant parameters, while the AUC-ROCs of the hepcidin/ferritin ratio (0.631, P = 0.188 and 0.684, P = 0.098) exhibited 90% and 89.5% sensitivity, respectively, in staging liver fibrosis.ConclusionOur results showed that the hepcidin/ferritin ratio is as effective as the APRI and maybe a better predictor for the diagnosis of liver fibrosis and discriminating its stages, with excellent sensitivity and specificity compared to its components.     

EUCAST disc diffusion criteria for the detection of mecA-Mediated β-lactam resistance in Staphylococcus pseudintermedius: oxacillin versus cefoxitin

ObjectivesUntil recently, the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommended the cefoxitin disc to screen for mecA-mediated β-lactam resistance in Staphylococcus pseudintermedius. A recent study indicated that cefoxitin was inferior to oxacillin in this respect. We have re-evaluated cefoxitin and oxacillin discs for screening for methicillin resistance in S. pseudintermedius.MethodsWe included 224 animal and human S. pseudintermedius isolates from Europe (n = 108) and North America (n = 116), of which 109 were mecA-positive. Disc diffusion was performed per EUCAST recommendations using 30-μg cefoxitin and 1-μg oxacillin discs from three manufacturers and Mueller–Hinton agar from two manufacturers.ResultsCefoxitin inhibition zones ranged from 6 to 33 mm for mecA-positive S. pseudintermedius (MRSP) and from 29 to 41 mm for mecA-negative S. pseudintermedius (MSSP). The corresponding oxacillin zone intervals were 6–20 mm and 19–30 mm. For cefoxitin 16% (95% CI 14.8–18.0%) of the isolates were in the area where positive and negative results overlapped. For oxacillin the corresponding number was 2% (1.6–2.9%). For oxacillin a breakpoint of susceptible (S) ≥ 20 mm and resistant (R) <20 mm resulted in only 0.4% and 1.1% very major error and major error rates respectively.ConclusionsThis investigation confirms that the 1-μg oxacillin disc predicts mecA-mediated methicillin resistance in S. pseudintermedius better than the 30-μg cefoxitin disc. For a 1-μg oxacillin disc we propose that 20 mm should be used as cut off for resistance, i.e. isolates with a zone diameter <20 mm are resistant to all β-lactam antibiotics except those with activity against methicillin-resistant staphylococci.     

Intracellular esterase activity of Candida albicans and its correlation with pathogenicity in mice

ObjectiveTo determine the virulence of clinical Candida albicans isolates and intracellular esterase activity in differentiating the virulent strains.Materials and methodsThe virulence of 17 isolates of C. albicans was determined in BALB/c mice with Candidiasis. The esterase activity against five substrates was assayed by a colorimetric method.ResultsThe results showed that the virulence of C. albicans isolates was considerably different from each other. The esterase activity against each of the five substrates did not show significant correlation with the virulence of the isolates. Comparison of the mean esterase activity of the human and animal isolates showed significant differences against some of the substrates.ConclusionIt is concluded that this study showed a positive but not significant correlation between some intracellular esterase activities and the C. albicans virulence.     

Clinical characteristics and risk factors for children with norovirus gastroenteritis in Taiwan

BackgroundNorovirus is a common acute gastroenteritis (AGE) pathogen across all age groups worldwide, which is difficult to differentiate from other pathogens. This study aimed to understand the clinical characteristics and risk factors of norovirus gastroenteritis among children in Taiwan.MethodsA prospective AGE surveillance study was conducted in children aged ≤5 years who were hospitalized in 10 major hospitals in Taiwan between 2014 and 2017. The non-AGE control group included healthy children who were matched based on age, gender, season, and geographic area.ResultsOverall, 674 norovirus gastroenteritis patients were enrolled. Fever (p < 0.001), mucoid stool (p < 0.001), and bloody stool (p < 0.001) occurred less frequently among norovirus gastroenteritis patients. Norovirus gastroenteritis patients yielded lower CRP values on admission (21.78 ± 36.81 vs. 46.26 ± 58.12 mg/L, p < 0.001) than non-norovirus controls. Norovirus gastroenteritis patients were associated with higher direct contact rates with AGE patients within 1 week (30.5% vs. 0.97%, p < 0.001), lower hand wash rates before meals (21.6% vs. 15.4%, p = 0.001), lower human milk (15.8% vs. 19.8%, p = 0.045) and guava consumption rates (17.8% vs. 24.3%, p = 0.002) than non-AGE participants.ConclusionsBody temperature, stool characteristics, and CRP value can help distinguish the norovirus from other pathogens. The major risk factor of norovirus AGE is contact with AGE patient. Higher frequency of hand wash, human milk, and guava intake may be protective against norovirus gastroenteritis.     

Evaluation of the inoculum effect of new antibiotics against carbapenem-resistant enterobacterales

ObjectivesNew antibiotics have been developed to treat multidrug-resistant Enterobacterales. We evaluated the impact of the inoculum size on minimal inhibitory concentrations (MICs) of recently commercialized antibiotics.MethodsWe focused on 40 clinical carbapenemase-producing Enterobacterales and evaluated the impact of the inoculum size on the MICs to cefiderocol and to new β-lactams/β-lactamase inhibitors (ceftolozane-tazobactam, ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam) at usual and high inocula (10⁵ and 10⁷ CFU/mL, respectively).ResultsAt usual inoculum, 15% were resistant to cefiderocol (n = 6), 30% to meropenem-vaborbactam (n = 12), 42.5% to ceftazidime-avibactam (n = 17), 55% to imipenem-relebactam (n = 22), and 90% to ceftolozane-tazobactam (n = 36). At higher inoculum, a switch from susceptible to resistant category was observed for 88% (n = 30/34; CI, 71.6–96.2), 75% (n = 3/4; CI, 21.9–98.7), 72% (n = 13/18; CI, 46.4–89.3), 50% (n = 14/28; CI, 31.1–68.9), and 8.7% (n = 2/23; CI, 1.5–29.5) isolates regarding cefiderocol, ceftolozane-tazobactam, imipenem-relebactam, meropenem-vaborbactam, and ceftazidime-avibactam, respectively.DiscussionCefiderocol and meropenem-vaborbactam were the most efficient against carbapenemase-producing Enterobacterales at usual inoculum. When increasing inoculum to 10⁷ CFU/mL, all of the molecules were impacted, particularly cefiderocol and imipenem-relebactam, while others, such as ceftazidime-avibactam, remain mildly affected. Our in vitro results deserved to be confirmed in vivo.     

In vitro activity of ibrexafungerp against Candida species isolated from blood cultures. Determination of wild-type populations using the EUCAST method

ObjectivesIbrexafungerp is a new oral glucan synthase inhibitor with in vivo and in vitro activity against Candida spp., including echinocandin- and azole-resistant isolates. We studied the in vitro activity of ibrexafungerp against Candida species isolated from blood cultures and assessed wild-type upper limits against the five Candida species most frequently associated to candidaemia.MethodsIsolates (n = 958) causing incident episodes of candidaemia in patients admitted to Gregorio Marañón hospital (Madrid, Spain) between January 2007 and April 2021 were studied. Antifungal susceptibility to ibrexafungerp, fluconazole, micafungin and anidulafungin was tested (EUCAST E.Def 7.3.2) and wild-type upper limits determined against C. albicans (n = 462), C. glabrata (n = 120), C. parapsilosis (n = 249), C. tropicalis (n = 73) and C. krusei (n = 24). fksgene sequencing was carried out in non-wild-type isolates.ResultsIbrexafungerp showed antifungal in vitro activity against the studied isolates. Wild-type upper limits for ibrexafungerp were >0.25 mg/L against C. albicans, >1 mg/L against C. parapsilosis, C. glabrata, and C. tropicalis, and >2 mg/L against C. krusei. Percentages of ibrexafungerp non-wild-type isolates were low (C. parapsilosis and C. krusei, 0%; C. albicans, 0.22% (1/462); C. glabrata, 0.83% (1/120); and C. tropicalis, 1.37% (1/73)). Ibrexafungerp proved in vitro activity against fluconazole- or echinocandin-resistant isolates.DiscussionWe show in vitro activity of ibrexafungerp against the tested Candida species. Furthermore, we provide ibrexafungerp wild-type upper limits, which allows defining the wild-type populations of the five most relevant Candida species.     

Comparison of the Copan WASPLab incorporating the BioRad expert system against the SIRscan 2000 automatic for routine antimicrobial disc diffusion susceptibility testing

ObjectivesThis study investigated the agreement at the categorical level between the Copan WASPLab incorporating the BioRad expert system against the SIRscan 2000 automatic for antimicrobial disc diffusion susceptibility testing.MethodsThe 338 clinical strains (67 Pseudomonas aeruginosa, 19 methicillin-resistant Staphylococcus aureus, 75 methicillin-sensitive S. aureus and 177 Enterobacterales isolates) analysed in this study were non-duplicate isolates obtained from consecutive clinical samples referred to the clinical bacteriology laboratory at Geneva University Hospitals between June and August 2019. For the WASPLab the inoculum suspension was prepared in strict accordance with the manufacturer's instruction (Copan WASP srl, Brescia, Italy) by adding 2 mL of the 0.5 McFarland primary suspension used for the SIRscan analysis into a sterile tube filled with 4 mL of sterile saline (1:3 dilution). The inoculum (2 × 30 μL loop/spreader) was spread over the entire surface of Mueller–Hinton agar plates according to the AST streaking pattern defined by Copan. The antibiotic discs were dispensed by the WASP and inoculated media were loaded on conveyors for transfer to the automatic incubators. The plates were incubated for 16 h, and several digital images were acquired. Inhibition zone diameters were automatically read by the WASPLab and were adjusted manually whenever necessary. For the SIRscan 2000 automatic, the antimicrobial disc diffusion susceptibility testing was performed according to the EUCAST guidelines. The gradient strip method was used to resolve discrepancies.ResultsThe overall categorical agreement between the compared methods reached 99.1% (797/804; 95% CI 98.2%–99.6%), 99.5% (1029/1034; 95% CI 98.9%–99.8%), and 98.8% (2798/2832; 95% CI 98.3%–99.1%) for P. aeruginosa, S. aureus and the Enterobacterales, respectively.ConclusionsWASPLab incorporating the BioRad expert system provides a fully automated solution for antimicrobial disc diffusion susceptibility testing with equal or better accuracy than other available phenotypic methods.