Environmental surveillance of Legionella pneumophila in distal water supplies of a hospital for early identification & prevention of hospital-acquired legionellosis

Background & objectives: Legionella pneumophila, a ubiquitous aquatic organism is found to be associated with the development of the community as well as hospital-acquired pneumonia. Diagnosing Legionella infection is difficult unless supplemented with, diagnostic laboratory testing and established evidence for its presence in the hospital environment. Hence, the present study was undertaken to screen the hospital water supplies for the presence of L. pneumophila to show its presence in the hospital environment further facilitating early diagnosis and prevention of hospital-acquired legionellosis. Methods: Water samples and swabs from the inner side of the same water taps were collected from 30 distal water outlets present in patient care areas of a tertiary care hospital. The filtrate obtained from water samples as well as swabs were inoculated directly and after acid buffer treatment on plain and selective (with polymyxin B, cycloheximide and vancomycin) buffered charcoal yeast extract medium. The colonies grown were identified using standard methods and confirmed for L. pneumophila by latex agglutination test. Results: About 6.66 per cent (2/30) distal water outlets sampled were found to be contaminated with L. pneumophila serotype 2-15. Isolation was better with swabs compared to water samples. Interpretation & conclusions: The study showed the presence of L. pneumophila colonization of hospital water outlets at low levels. Periodic water sampling and active clinical surveillance in positive areas may be done to substantiate the evidence, to confirm or reject its role as a potential nosocomial pathogen in hospital environment

Microbial contamination of soft contact lenses & accessories in asymptomatic contact lens users

Background & objectives: With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Methods: Four samples each from 50 participants (n=200) were collected from the lenses, lens care solutions, lens care solution bottles and lens cases along with a questionnaire regarding their lens use. The samples were inoculated onto sheep blood agar, Mac Conkey′s agar and Sabouraud′s dextrose agar. Organisms were identified using standard laboratory protocols. Results: Overall rate of microbial contamination among the total samples was 52 per cent. The most and the least contaminated samples were found to be lens cases (62%) and lens care solution (42%), respectively. The most frequently isolated contaminant was Staphylococcus aureus (21%) followed by Pseudomonas species (19.5%). Majority (64%) of the participants showed medium grade of compliance to lens cleaning practices. Rate of contamination was 100 and 93.75 per cent respectively in those participants who showed low and medium compliance to lens care practices as compared to those who had high level of compliance (43.75%) ( p0 <0.05). Interpretation & conclusions: Lens care practices amongst the participants were not optimum which resulted into high level contamination. Hence, creating awareness among the users about the lens care practices and regular cleaning and replacements of lens cases are required

Diagnostic accuracy of Lipoarabinomannan detection by lateral flow assay in pleural tuberculosis

Abstract Background Lipoarabinomannan (LAM) antigen serves as an attractive biomarker to diagnose Tuberculosis (TB). Given the limitations of current diagnostic modalities for Pleural TB, current study evaluated LAM’s potential to serve as a point-of-care test to diagnose pleural TB. Methods A cross sectional, diagnostic accuracy study was conducted during February to November 2021 in a tertiary care hospital in India. LAM antigen detection was performed on pleural fluid as well as early morning urine specimen of suspected pleural TB patients by “Alere/ Abott Determine TB LAM” lateral flow assay (LAM-LFA). The results were compared to microbiological reference standards/MRS (Mycobacterial culture or NAAT) and Composite reference standards/CRS (MRS plus Clinico-radiological diagnosis). Results A total of 170 subjects were included in the analysis, including 26 with Definite TB, 22 with Probable TB, and 122 with No TB. Compared to MRS and CRS, the sensitivity (61.54% & 45.83%) and positive predictive value (PPV) (57.14 & 78.57%) of Pleural LAM-LFA testing were found to be suboptimal, whereas the specificity (91.67% & 95.08%) and negative predictive value (NPV) (92.96% & 81.69%) of the assay were found to be good. Urinary LAM-LFA performed even worse than pleural LAM-LFA, except for its higher specificity against MRS and CRS (97.2% and 98.3%, respectively). Specificity and PPV of pleural LAM detection increased to 100% when analysed in a subgroup of patients with elevated ADA levels (receiver operating curve analysis-derived cut off value > 40 IU/ml). Conclusion Detection of LAM antigen by LFA directly from pleural fluid was found to be a useful test to predict absence of the disease if the test is negative rather than using as a POCT for diagnosis

Effective pragmatic approach of diagnosis of multidrug-resistant tuberculosis by high-resolution melt curve assay

Background: Effective management of multidrug-resistant tuberculosis (MDR-TB) requires cost-effective and rapid screening of rifampicin (RIF) and isoniazid (INH) resistance. Accordingly, a highly promising high-resolution melting (HRM) analysis was evaluated in the detection of mutation in rpoB, katG gene and inhA promoter region in Mycobacterium tuberculosis isolates. Methods: A total of 143 M. tuberculosis isolates comprising phenotypically confirmed 94 MDR and 49 sensitive isolates were analyzed by HRM following real-time-polymerase chain reaction in comparison to gold standard of targeted DNA sequencing of rpoB, katG gene and inhA promoter region. Results: HRM correctly identified MDR-TB by rapid and accurate detection of predominantly and infrequently occurring specific single nucleotide polymorphism in rpoB, katG gene and inhA promoter region. rpoB HRM showed sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 98% each respectively. Predominantly, S531 L/W (TCG → TTG/TGG) mutation accounted for 68.47% of RIF resistance followed by H526Y/R (13.04%, CAC → TAC/CGC), D516Y/V/G (10.86%, GAC → TAC/GTC/GGC), Q513P (4.34%, CAA → CCA), and one rare mutation at codon position L533A (CTG → CGG). Combined KatG and inhA HRM sensitivity, specificity, PPV, and NPV were 90%, 100%, 100%, and 84.48% respectively and detected frequent mutation at codon position S315T/I/N (70%, AGC → ACC, AGC → ACT, AGC → AAC) and rare mutation at codon position T314P (3.3%, ACC → CCC) and 329 (2.2%, GAC → GCC) of katG gene. In inhA, mutations were recorded at mostly promoter position − 15 (10%, C → T) and infrequently at − 8 (3.3%, T → G, T → C). HRM assay limitation noticed in recognizing silent mutation in rpoB as a mutant, nondetection of infrequent mutation S310A in katG, and the inability of detecting mutation outside the targeted region of investigated genes. Conclusion: HRM may prove to be a vital molecular assay in rapid screening of TB cases for early detection of MDR TB, leading to early evidenced-based initiation of antitubercular treatment that will significantly reduce MDR transmission

A retrospective observational insight into COVID-19 exposures resulting from personal protective equipment (PPE) breaches.

BackgroundHealthcare workers (HCWs) stand the risk of acquiring infection directly, while attending to patients or indirectly while handling and testing patient specimens. Considering this, the present study was planned to assess Personal Protective Equipment (PPE) breaches and exposures among HCWs working in COVID-19 wards/ screening areas and to evaluate their COVID-19 positivity rates post-exposure concerning the level of exposure, type of PPE breach, and the cadre of HCWs exposed in COVID-19 wards.MethodsThis retrospective cross-sectional study involved the analysis of all instances of PPE breaches which occurred during a period of nine months from June 2020 to February 2021 at a tertiary care level hospital in Central India. The analysis included all exposures involving any cadre of HCWs that occurred while handling the patients or while doffing the contaminated PPE in COVID -19 wards.ResultsA total of 347 PPE breaches were analyzed from the available records of the Hospital Infection Control team repository. Amongst the 347 breaches, 268 (77.2%) were classified as low-risk exposures and 79 (22.8%) as high-risk exposures. Cadre wise distribution of high and low-risk exposures revealed that, PPE breaches occurred most commonly in the category of nursing officers (n = 174, 50.1%). Among all of the breaches, 15.2% of high-risk exposures and 2.6% of low-risk exposures resulted in COVID-19 positivity with a cumulative positivity of 5.4%. Collectively, non-mask related breaches accounted for the majority (63.2%) of the positive COVID-19 cases.ConclusionAppropriate use of PPE by HCWs is vital for their protection. However, breaches in the use of PPE may occur while managing COVID-19 patients due to physical and mental exhaustion among HCWs resulting from work overload. Early identification and appropriate management of HCWs with high-risk exposures can help prevent transmission to other hospital staff and patients, thus preserving resources and workforce

Comparative analysis of various clinical specimens in detection of SARS-CoV-2 using rRT-PCR in new and follow up cases of COVID-19 infection: Quest for the best choice.

BackgroundAn appropriate specimen is of paramount importance in Real Time reverse transcription-polymerase chain reaction (rRT-PCR) based diagnosis of novel coronavirus (nCoV) disease (COVID-19). Thus, it's pertinent to evaluate various diversified clinical specimens' diagnostic utility in both diagnosis and follow-up of COVID-19.MethodsA total of 924 initial specimens from 130 COVID-19 symptomatic cases before initiation of treatment and 665 follow up specimens from 15 randomly selected cases comprising of equal number of nasopharyngeal swab (NPS), oropharyngeal swab (OPS), combined NPS and OPS (Combined swab), sputum, plasma, serum and urine were evaluated by rRT-PCR.ResultsDemographic analysis showed males (86) twice more affected by COVID-19 than females (44) (p = 0.00001). Combined swabs showed a positivity rate of 100% followed by NPS (91.5%), OPS (72.3%), sputum (63%), while nCoV was found undetected in urine, plasma and serum specimens. The lowest cycle threshold (Ct) values of targeted genes E, ORF1b and RdRP are 10.56, 10.14 and 12.26 respectively and their lowest average Ct values were found in combined swab which indicates high viral load in combined swab among all other specimen types. Analysis of 665 follow-up multi-varied specimens also showed combined swab as the last specimen among all specimen types to become negative, after an average 6.6 (range 4-10) days post-treatment, having lowest (15.48) and average (29.96) Ct values of ORF1b respectively indicating posterior nasopharyngeal tract as primary nCoV afflicted site with high viral load.ConclusionThe combined swab may be recommended as a more appropriate specimen for both diagnosis and monitoring of COVID-19 treatment by rRT-PCR for assessing virus clearance to help physicians in taking evidence-based decision before discharging patients. Implementing combined swabs globally will definitely help in management and control of the pandemic, as it is the need of the hour