Journal of medical microbiology最新文献

Introduction. The FilmArray blood culture identification panel (BCID) panel is a multiplex PCR assay with high sensitivity and specificity to identify the most common pathogens in bloodstream infections (BSIs).Hypothesis. We hypothesize that the BCID panel has good diagnostic performance for BSIs and can be popularized in clinical application.Aim: To provide summarized evidence for the diagnostic accuracy of the BCID panel for the identification of positive blood cultures.Methodology. We searched the MEDLINE, EMBASE and Cochrane databases through March 2021 and assessed the efficacy of the diagnostic test of the BCID panel. We performed a meta-analysis and calculated the summary sensitivity and specificity of the BCID panel. Systematic review protocols were registered in the International Prospective Register of Systematic Reviews (PROSPERO) (registration number CRD42021239176).Results. A total of 16 full-text articles were eligible for analysis. The overall sensitivities of the BCID panel on Gram-positive bacteria, Gram-negative bacteria and fungi were 97 % (95 % CI, 0.96-0.98), 100 % (95 % CI, 0.98-01.00) and 99 % (95 % CI, 0.87-1.00), respectively. The pooled diagnostic specificities were 99 % (95 % CI, 0.97-1.00), 100 % (95 % CI, 1.00-1.00) and 100 % (95 % CI, 1.00-1.00) for Gram-positive bacteria, Gram-negative bacteria and fungi, respectively.Conclusions. The BCID panel has high rule-in value for the early detection of BSI patients. The BCID panel can still provide valuable information for ruling out bacteremia or fungemia in populations with low pretest probability.

Introduction. Antibiotic resistance is a major threat to public health, particularly with methicillin-resistant Staphylococcus aureus (MRSA) being a leading cause of antimicrobial resistance. To combat this problem, drug repurposing offers a promising solution for the discovery of new antibacterial agents.Hypothesis. Menadione exhibits antibacterial activity against methicillin-sensitive and methicillin-resistant S. aureus strains, both alone and in combination with oxacillin. Its primary mechanism of action involves inducing oxidative stress.Methodology. Sensitivity assays were performed using broth microdilution. The interaction between menadione, oxacillin, and antioxidants was assessed using checkerboard technique. Mechanism of action was evaluated using flow cytometry, fluorescence microscopy, and in silico analysis.Aim. The aim of this study was to evaluate the in vitro antibacterial potential of menadione against planktonic and biofilm forms of methicillin-sensitive and resistant S. aureus strains. It also examined its role as a modulator of oxacillin activity and investigated the mechanism of action involved in its activity.Results. Menadione showed antibacterial activity against planktonic cells at concentrations ranging from 2 to 32 µg ml^-1, with bacteriostatic action. When combined with oxacillin, it exhibited an additive and synergistic effect against the tested strains. Menadione also demonstrated antibiofilm activity at subinhibitory concentrations and effectively combated biofilms with reduced sensitivity to oxacillin alone. Its mechanism of action involves the production of reactive oxygen species (ROS) and DNA damage. It also showed interactions with important targets, such as DNA gyrase and dehydroesqualene synthase. The presence of ascorbic acid reversed its effects.Conclusion. Menadione exhibited antibacterial and antibiofilm activity against MRSA strains, suggesting its potential as an adjunct in the treatment of S. aureus infections. The main mechanism of action involves the production of ROS, which subsequently leads to DNA damage. Additionally, the activity of menadione can be complemented by its interaction with important virulence targets.

Background. The spread of Enterobacteriaceae coproducing carbapenemases, 16S rRNA methylase and mobile colistin resistance proteins (MCRs) has become a serious public health problem worldwide. This study describes two clinical isolates of Klebsiella pneumoniae coharbouring bla _IMP-1, armA and mcr-10.Methods. Two clinical isolates of K. pneumoniae resistant to carbapenems and aminoglycosides were obtained from two patients at a hospital in Myanmar. Their minimum inhibitory concentrations (MICs) were determined by broth microdilution methods. The whole-genome sequences were determined by MiSeq and MinION methods. Drug-resistant factors and their genomic environments were determined.Results. The two K. pneumoniae isolates showed MICs of ≥4 and ≥1024 µg ml^-1 for carbapenems and aminoglycosides, respectively. Two K. pneumonaie harbouring mcr-10 were susceptible to colistin, with MICs of ≤0.015 µg ml^-1 using cation-adjusted Mueller-Hinton broth, but those for colistin were significantly higher (0.5 and 4 µg ml^-1) using brain heart infusion medium. Whole-genome analysis revealed that these isolates coharboured bla _NDM-1, armA and mcr-10. These two isolates showed low MICs of 0.25 µg ml^-1 for colistin. Genome analysis revealed that both bla _NDM-1 and armA were located on IncFIIs plasmids of similar size (81 kb). The mcr-10 was located on IncM2 plasmids of sizes 220 or 313 kb in each isolate. These two isolates did not possess a qseBC gene encoding a two-component system, which is thought to regulate the expression of mcr genes.Conclusion. This is the first report of isolates of K. pneumoniae coharbouring bla _NDM-1, armA and mcr-10 obtained in Myanmar.

The identification of the novel pneumococcal serotype 7D by Neufeld quellung reaction requires significant expertise. To circumvent this, we developed a simple serotype-specific PCR method to discriminate serotype 7D from the closely related serotypes 7C, 7B and 40. The established PCR was validated with the strain collection of the German National Reference Center for Streptococci (GNRCS). However, no isolate initially assigned as serotype 7B, 7C or 40 was identified as serotype 7D.

Introduction. Tigecycline is one of the important antibiotics available for treating infection caused by multiple-drug resistant pathogens. However, the conventional AST methods which are commonly used in clinical microbiology laboratories usually lead to false intermediate or resistant results in testing tigecycline susceptibility, and further mislead clinical antimicrobial therapies.Hypothesis. The modified Kirby-Bauer disc diffusion (mKB) method was performed based on the traditional standard Kirby-Bauer disc diffusion (sKB) method.Aim. To evaluate a modified Kirby-Bauer disc diffusion (mKB) method for tigecycline susceptibility testing, for the purpose of providing accurate tigecycline susceptibility results in clinical practice.Methodology. A total of 4271 nonduplicate clinical strains were isolated from 37 hospitals across China to perform the mKB method, standard Kirby-Bauer disc diffusion (sKB) method, comparing with the reference broth microdilution (BMD) according to the CLSI. Parameters of categorical agreement (CA), minor errors (mE), major errors (ME), and very major errors (VME) were used in this methodological evaluation research.Results. BMD testing showed that 91.3-98.9 % of the A. baumannii, K. pneumoniae, E. coli, E. cloacae, S. marcescens, and C. freundii strains were susceptible, while 0-3.1% strains were resistant to tigecycline. When testing A. baumannii, mKB demonstrated higher CA than sKB (90.6 % vs 44.8 %) compared to reference BMD. The mE (9.0 % vs 45.2 %), ME (0.5 % vs 10.6 %) and VME (both 0 %) all satisfied the acceptability criteria. mKB also showed higher CA (87.2 % vs 52.0 %) than sKB in comparison with BMD when testing Enterobacterales (mainly K. pneumonia). The ME (0.45 % vs 8.1 %) and VME (both 0 %) but not mE (12.4 % vs 40.4 %) met the acceptability criteria.Conclusion. The mKB method can test bacterial susceptibility to tigecycline more accurately than sKB. For the tigecycline-intermediate or -resistant strains by sKB method, BMD or mKB method should be used to verify the results and report reliable tigecycline susceptibility results.

Introduction. COVID-19 caused by SARS CoV-2 continues to be a major health concern globally. Methods for detection of the disease are necessary for public health efforts to monitor the spread of this disease as well as for detecting the emergence of new variants.Gap statement. Collection of Nasopharyngeal swab (NPS), the gold standard sample for the detection of COVID-19 infection by RT-qPCR is invasive and requires the expertise of a trained medical provider. This highlights the need for validating less invasive samples that can be self-collected without the need for trained medical provider.Aim. To validate saliva and tongue swab as potential samples for the diagnosis of COVID-19.Methodology. Adult and paediatric cases who had acute influenza like illness were enrolled in the study. The study involved comparison of Nucleic Acid Amplification Tests (NAAT) results for the detection of COVID-19 obtained by using saliva and tongue swab with that of NPS.Result and Conclusion. The sensitivity and specificity of saliva as sample for COVID-19 detection were found to be 71 and 88% respectively whereas those of tongue swab as sample were 78 and 90 %. Further validation was based on the positive and negative predictive values, the likelihood ratio, agreement percentage and the kappa statistic. The findings of the study point towards tongue swab and saliva as suitable alternative samples for the diagnosis of COVID-19 with a slightly higher accuracy and agreement for tongue swab than saliva. However considering the fatality of COVID-19, they are better suited for mass screening of people than for diagnosis.