Indian Journal of Medical Microbiology最新文献

Background

Paediatric community-acquired pneumonia (CAP) is a major public health challenge in children, requiring accurate and timely diagnosis of causative pathogens for effective antibiotic treatment. We aimed to explore the utility of next-generation sequencing (NGS) in precise diagnosis of pediatric CAP and its effect on treatment outcome of these children.

Methods

A systematic review and meta-analysis was conducted to compare NGS-guided antibiotic therapy with conventional methods in pediatric CAP. The study followed PRISMA guidelines and searched for electronic databases including PubMed/MEDLINE, Embase, Scopus, and Web of Sciences from 2012 to 2023. Studies on pediatric CAP (<18 years) using NGS alongside conventional diagnostics, were included.

Results

Database search identified 721 studies and 6 were finally included for review, published between 2019 and 2023. Meta-analysis revealed an overall odds ratio of 2.39 (95 % CI 1.22, 3.56) for NGS vs conventional methods. Detection rates using NGS ranged from 86% to 100 %, surpassing conventional methods (26%–78.51 %). Five out of selected 6 studies (83.33 %) have documented that change in treatment based on NGS finding resulted in clinical improvement of patients. There was no significant heterogeneity and potential bias among the studies. Nearly 80 % of the studies were of good quality.

Conclusion

The NGS (particularly metagenomic sequencing) is a promising tool for diagnosing paediatric CAP with high accuracy. It can improve antibiotic usage practices and patient outcomes, potentially reducing antibiotic resistance. Based on meta-analysis, training of healthcare professionals in NGS methodologies and result interpretation is highly recommended.

Background

Lung cancer and tuberculosis share similar risk factors, clinical spectrum, radiological features and it is difficult to differentiate but it is important to diagnose both conditions for targeted therapy and better outcome.

Aims

Our primary objective was to estimate the proportion of TB in primary biopsy proven non-small cell lung carcinoma (NSCLC) cases.

Material & methods

This prospective observational study was conducted in the Departments of Medicine/Pulmonary Medicine/Medical Oncology and Microbiology at the All India Institute of Medical Sciences, New Delhi for a period of 2 years (January 2020–December 2021). Patients with biopsy proven, primary non-small cell lung cancer were recruited and sputum samples were subjected to microbiological investigations to confirm tuberculosis. Comparison was done in two groups of lung cancer patients with confirmed TB (Group A) and without confirmed tuberculosis (Group B).

Results

Total 75 patients with biopsy proven, primary NSCLC were recruited and 16 % (12/75) were diagnosed with confirmed TB. Adenocarcinoma (36.48 %) and Squamous cell carcinoma (33.44 %) were the two predominant histopathological subtypes of NSCLC. About 57 (76 %) of them were found to be in stage IV of Lung cancer at initial presentation itself (75 % in group A & 74.6 % in group B; p value < 0.80). A majority of patients (11/12 cases; 91 %) of group A were males with a mean age of 59 ± 7.5 years. The upper lobes of the lung were involved in 65 % (49/75) of the cases and showing a mass lesion on imaging (75 % in group A & 65 % in group B; p value < 0.52). Kaplan Meier survival revealed a median survival time of 11 months in subjects with only NSCLC and a median survival time of 4 months in the group with concomitant TB and NSCLC (p value < 0.44).

Purpose

Carbapenem-resistant Enterobacterales (CRE) are a global concern due to their high mortality rates and limited therapeutics. CRE-caused bloodstream infections (BSIs) are challenging to manage, especially in healthcare settings. This study aimed to investigate the predictors of mortality in BSI patients caused by CRE.

Methods

A single center prospective study to examine the characteristics of BSI caused by CRE in a large academic hospital over 15 months. The main outcomes were microbiological characteristics and clinical outcomes of patients at 28 days based on a step-wise regression analysis.

Results

A total of 76 episodes of BSI due to CRE were included. The study found that the most common type of carbapenemase was OXA-48 (69.7 %, n = 53), followed by the co-existence of OXA-48 and MBL (26.3 %, n = 20), with Klebsiella pneumoniae being the most common (90 %, n = 69). Patients with OXA-48-BSI were more likely to have a urinary source of infection, while patients with MBL-BSI were more likely to have a non-urinary source of infection. All cases (100 %) had medical devices. Around 30.3 % of patients received effective empirical treatment, while 61.8 % received adequate therapy at 48 h. The overall mortality rate was 42.1 % (n = 32), and the main predictors of mortality in this study were the presence of sepsis and inadequate initial therapy, while age >65 predicted mortality in the linear regression but not the stepwise regression model.

Conclusion

CRE-BSIs are a serious health threat. The study highlights the need for preventive strategies focused on high-risk patients and proper device management to reduce BSI.

Background

There is a high diversity of beta-lactamases in gram negative pathogens, making them difficult to treat. In the presence of OXA-1 and ampC, PTZ is no longer clinically relevant when treating Enterobacterales expressing ESBLs. Further, MBL infections are often treated with the combination of ceftazidime/avibactam with aztreonam. . It has recently been reported that NDM-expressing E. coli isolates co-harboring PBP3 insert develops resistance to this triple combination.

Methods

A pentaplex PCR is developed and validated to simultaneously detect bla_CTX-M, bla_OXA-1, bla_CMY, bla_NDM, and the PBP3 insert in whole genome sequenced E. coli and K. pneumoniae isolates. In addition, the isolates chosen for pentaplex PCR evaluation were tested for their minimum inhibitory concentrations (MICs) against piperacillin/tazobactam, cefoperazone/sulbactam (C/S), ertapenem, imipenem, meropenem, ceftazidime/avibactam, aztreonam/avibactam, cefepime/taniborbactam, and cefiderocol.

Results

The developed pentaplex PCR showed 100 % reproducibility with the antimicrobial resistance profile generated from whole genome sequenced data. PTZ and C/S are not effective against ESBL and/or OXA-1 expressing E. coli and K. pneumoniae isolates and do not offer any activity against CMY co-producers. Further, the combined effect of CMY, NDM and PBP3 inserts impacts aztreonam/avibactam activity and reduces the susceptibility to 40 % in E. coli isolates. While, aztreonam/avibactam showed potent activity against NDM-expressing K. pneumoniae isolates. Importantly, cefepime/taniborbactam and cefiderocol showed limited activity against NDM-expressing E. coli and K. pneumoniae isolates.

Conclusion

The pentaplex PCR was effective in detecting four beta-lactamases (bla_CTX-M, bla_OXA-1, bla_CMY, bla_NDM) as well as PBP3 inserts. It is expected that using pentaplex PCR as a diagnostic test for resistance detection in clinical practice will improve patient outcomes by providing prompt and targeted treatment.

Fungi belonging to Apiospora are phytopathogens not reported from human infections. Here, we report a case of keratitis due to Apiospora species in a carpenter who sustained a bamboo shrapnel injury to his eye when he was not wearing safety goggles. Thin hyaline septate hyphae were found on calcofluor white with potassium hydroxide (Calco-KOH) preparation of the scraping. A nonsporulating white mold grew from the corneal scrape, identified as A. rasikravindrae by Internal Transcribed Spacer (ITS) region sequencing. The patient improved with debridement and topical antifungal therapy. Educational interventions are needed to encourage safety goggles to prevent corneal injuries and blindness.

Background

The diagnosis of Tuberculosis (TB) has been a challenge till the advent of rapid molecular diagnostic tests. The traditional diagnostic tests have its own limitations with regard to its performance or the turnaround time. Truenat MTB Plus assay, a battery-operated molecular assay developed in India has been introduced for its use in pulmonary TB (PTB). However, the diagnostic accuracy of the assay is not well studied in comparison with Mycobacterial culture, especially for extrapulmonary TB (EPTB).

Aim

We aimed at evaluating the diagnostic accuracy of Truenat MTB Plus assay for both PTB and EPTB comparing with culture for adult population.

Methods

The specimens from presumptive PTB and EPTB patients were processed for Truenat MTB Plus assay, solid or liquid culture and AFB staining. The electronic data of all the specimen reports collected retrospectively were analysed for the sensitivity and specificity.

Results

Out of the 736 samples which had valid culture reports, 364 (49.4 %) were respiratory and 372 (50.6 %) were extrapulmonary specimens. The test positivity rate for smear microscopy, Truenat MTB Plus assay and culture was 3.7 % (27), 8.2 % (60), 7.1 % (52) respectively. Of the 60 Truenat MTB Plus positive patients with TB, 33 (55 %) were PTB and 27 (45 %) were EPTB. We estimated overall sensitivity and specificity of Truenat MTB Plus as 90 % (95 % CI: 73.4–97.8) and 98. 2 (95 % CI:96–99.3) respectively for the detection of PTB. The overall sensitivity and specificity for EPTB was 81.8 % (95 % CI: 59.7–94.8) and 97.4 % (95 % CI: 95.1–98.8) respectively.

Conclusions

Truenat MTB Plus assay has comparable diagnostic accuracy with other molecular assays. The Truenat MTB Plus assay can be used for the diagnosis of PTB and EPTB, especially in resource limited settings.

Background

& objective: The existence of visually identical cryptic Aspergillus species that can be distinguished only by molecular techniques is becoming more widely acknowledged. For the majority of antifungal drugs, these are known to exhibit a greater minimal inhibitory concentration in vitro. For the purpose of receiving the proper care, it is crucial to identify these species at right time. Our aim in this work is to identify and describe the Aspergillus species that are cryptic from all of the clinical samples.

Methods

Routine samples from inpatients and outpatients received in department of Microbiology, All India Institute of Medical Sciences, New Delhi, showing growth of Aspergillus species were included in this study. Phenotypic and Matrix Assisted Laser Desorption Ionisation - Time of Flight identified isolates were analysed for cryptic species, by PCR and ITS/ß – tubulin sequencing. In accordance with CLSI recommendations, antifungal susceptibility testing was conducted using micro broth dilution.

Results

Of the 94 isolates, 54 A. fumigatus, 34 A. flavus, 3 A. nidulans, 2 A. terreus, and 1 A. niger were morphologically identified. MALDI-TOF misidentified 2 A. nidulans isolates and 1 A, stellatus isolate. The ß – tubulin sequence analysis revealed that 2 isolates (2.08 %) were cryptic, one was A. stellatus and another one was A. tubingensis.

Purpose

The Centers for Disease Control and Prevention has classified methicillin-resistant S aureus (MRSA) as a serious public health threat. The escalating minimum inhibitory concentration (MIC) of standard anti-methicillin-resistant S aureus (MRSA) drugs within the susceptible range, known as "MIC creep," jeopardizes their effectiveness against MRSA infections, posing additional challenges in managing MRSA infections. This cross-sectional study was conducted in a tertiary care hospital in Central India to assess the susceptibility trends of clinical MRSA isolates against commonly used anti-MRSA drugs and to observe MIC creep, if any, over three years (2020–2022).

Methods

The study included 158 non-repetitive clinical MRSA isolates. The MICs of vancomycin, teicoplanin, and linezolid were determined in MRSA strains using agar dilution, while the MIC of daptomycin was performed by broth microdilution. MIC creep was assessed by calculating MIC50, MIC90, Modal MIC, G-mean MIC, and susceptible and resistant percentages for the fiscal years 2020, 2021, and 2022.

Results

Of the 158 MRSA isolates, none were resistant to vancomycin, teicoplanin, and daptomycin, but two showed resistance to linezolid (LRSA). However, fifteen isolates showed intermediate resistance to vancomycin (VISA), and five showed intermediate resistance to teicoplanin (TISA). MIC of these anti-MRSA drugs increased in 2021 and 2022 compared to 2020. G-mean MIC for vancomycin, teicoplanin, and linezolid in MRSA strains increased significantly over the study period, while daptomycin MIC remained relatively stable, with a slight increase in 2021 and 2022. There was a high resistance rate for clindamycin, doxycycline, and chloramphenicol among VISA, TISA, and LRSA isolates compared to MRSA.

Conclusions

During the three years of the study, “MIC creep” was observed in vancomycin, teicoplanin, and linezolid and, to some extent, for daptomycin in MRSA strains. The recovery of VISA, TISA, and linezolid-resistant MRSAs is worrisome, suggesting possible MRSA treatment failure and being a forerunner of resistant strains.