Evaluation of MicroScan Bacterial Identification Panels for Low-Resource Settings

Simple Imaging System for Label-Free Identification of Bacterial Pathogens in Resource-Limited Settings

Fast, accurate, and affordable bacterial identification methods are paramount for the timely treatment of infections, especially in resource-limited settings (RLS). However, today, only 1.3% of the sub-Saharan African diagnostic laboratories are performing clinical bacteriology. To improve this, diagnostic tools for RLS should prioritize simplicity, affordability, and ease of maintenance, as opposed to the costly equipment utilized for bacterial identification in high-income countries, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In this work, we present a new high-throughput approach based on a simple wide-field (864 mm2) lensless imaging system allowing for the acquisition of a large portion of a Petri dish coupled with a supervised deep learning algorithm for identification at the bacterial colony scale. This wide-field imaging system is particularly well suited to RLS since it includes neither moving mechanical parts nor optics. We validated this approach through the acquisition and the subsequent analysis of a dataset comprising 252 clinical isolates from five species, encompassing some of the most prevalent pathogens. The resulting optical morphotypes exhibited intra- and interspecies variability, a scenario considerably more akin to real-world clinical practice than the one achievable by solely concentrating on reference strains. Despite this variability, high identification performance was achieved with a correct species identification rate of 91.7%. These results open up some new prospects for identification in RLS. We released both the acquired dataset and the trained identification algorithm in publicly available repositories.

Carbapenemase-Producing Bacteria Isolated from ICU Patients of a Peruvian Government Hospital during the COVID-19 Pandemic: A Descriptive Analysis

Background and Objectives: In Peru, the presence of antimicrobial-resistant bacteria is a constant concern in hospitals and has likely increased in frequency during the pandemic. The objective of the study was to analyze the frequency of carbapenemase-producing bacteria resistant to two carbapenems (Imipenem and Meropenem), which were isolated from Peruvian patients in the intensive care unit of the Victor Lazarte Echegaray Hospital in Trujillo (Peru) during the COVID-19 pandemic. Materials and Methods: The biological samples of the patients hospitalized in the ICU were processed in the Microbiology Diagnostic Laboratory of the Víctor Lazarte Echegaray Hospital between May 2021 and March 2022. Antimicrobial sensitivity was determined with the automated system AutoScan-4, and for the identification of the type of carbapenemase, the RESISIT-3 O.K.N K-SET cassettes were used. Results: The results show that 76 cultures (76/129) had resistance to the two carbapenems (imipenem or meropenem), where the most frequent were Klebsiella pneuomoniae (31.6%), Pseudomonas aeruginosa (26.3%), and Acinetobacter baumannii (14.5%). Pseudomonas aeruginosa cultures showed at least three carbapenemase types (KPC, NDM, and OXA-48), while A. baumannii, Escherichia coli, and Burkholderia cepacia complex presented at least two carbapenemases (NDM and OXA-48). The carbapenemase NDM was detected in Enterobacter cloacae, Morganella morganii, and Proteus mirabilis, while KPC was present in all Klebsiella pneumoniae and Klebsiella oxytoca cultures. Conclusions: The samples from patients hospitalized in the Victor Lazarte Echegaray Hospital ICU showed a high prevalence of imipenem- and meropenem-resistant bacteria. These findings are relevant and concerning from the perspective of antibiotic-resistant bacteria monitoring, control, and disinfection. Thus, an appropriate antibiotic policy must be implemented.

Validation of Three MicroScan® Antimicrobial Susceptibility Testing Plates Designed for Low-Resource Settings

Easy and robust antimicrobial susceptibility testing (AST) methods are essential in clinical bacteriology laboratories (CBL) in low-resource settings (LRS). We evaluated the Beckman Coulter MicroScan lyophilized broth microdilution panel designed to support Médecins Sans Frontières (MSF) CBL activity in difficult settings, in particular with the Mini-Lab. We evaluated the custom-designed MSF MicroScan Gram-pos microplate (MICPOS1) for Staphylococcus and Enterococcus species, MSF MicroScan Gram-neg microplate (MICNEG1) for Gram-negative bacilli, and MSF MicroScan Fastidious microplate (MICFAST1) for Streptococci and Haemophilus species using 387 isolates from routine CBLs from LRS against the reference methods. Results showed that, for all selected antibiotics on the three panels, the proportion of the category agreement was above 90% and the proportion of major and very major errors was below 3%, as per ISO standards. The use of the Prompt inoculation system was found to increase the MIC and the major error rate for some antibiotics when testing Staphylococci. The readability of the manufacturer’s user manual was considered challenging for low-skilled staff. The inoculations and readings of the panels were estimated as easy to use. In conclusion, the three MSF MicroScan MIC panels performed well against clinical isolates from LRS and provided a convenient, robust, and standardized AST method for use in CBL in LRS.

Identification and Characterization of a New Serratia proteamaculans Strain That Naturally Produces Significant Amount of Extracellular Laccase

Natural biodegradation processes hold promises for the conversion of agro-industrial lignocellulosic biomaterials into biofuels and fine chemicals through lignin-degrading enzymes. The high cost and low stability of these enzymes remain a significant challenge to economic lignocellulosic biomass conversion. Wood-degrading microorganisms are a great source for novel enzyme discoveries. In this study, the decomposed wood samples were screened, and a promising γ-proteobacterial strain that naturally secreted a significant amount of laccase enzyme was isolated and identified as Serratia proteamaculans AORB19 based on its phenotypic and genotypic characteristics. The laccase activities in culture medium of strain AORB19 were confirmed both qualitatively and quantitatively. Significant cultural parameters for laccase production under submerged conditions were identified following a one-factor-at-a-time (OFAT) methodology: temperature 30°C, pH 9, yeast extract (2 g/l), Li+, Cu2+, Ca2+, and Mn2+ (0.5 mM), and acetone (5%). Under the selected conditions, a 6-fold increase (73.3 U/L) in laccase production was achieved when compared with the initial culturing conditions (12.18 U/L). Furthermore, laccase production was enhanced under alkaline and mesophilic growth conditions in the presence of metal ions and organic solvents. The results of the study suggest the promising potential of the identified strain and its enzymes in the valorization of lignocellulosic wastes. Further optimization of culturing conditions to enhance the AORB19 strain laccase secretion, identification and characterization of the purified enzyme, and heterologous expression of the specific enzyme may lead to practical industrial and environmental applications.

Comparison of Zinc Concentrations in the Broth of Commercial Automated Susceptibility Testing Devices (Vitek 2, MicroScan, BD Phoenix, and Sensititre)

Up to 4-fold differences in zinc concentrations have been observed in commercial broth routinely utilized for susceptibility testing via manual broth microdilution. Herein, we report the concentration of zinc in the broth of common automated susceptibility testing (AST) platforms (Vitek, MicroScan, BD Phoenix, and Sensititre). For AST platforms with lyophilized broth contents (Vitek and MicroScan), wells were rehydrated with appropriate diluent, and contents were aliquoted out for zinc assay. Aliquots from the manufacturer-specific broth (premade cation-adjusted Mueller-Hinton broth [caMHB]) for BD Phoenix and Sensititre were also assayed by inductively coupled plasma mass spectrometry. Up to a 10-fold difference in zinc concentrations was observed across the 4 platforms (MicroScan: 0.46 mg/L; BD Phoenix: 1.16 mg/L; Vitek: 1.22 mg/L; Sensititre: 4.49 mg/L). Attention should be given to the supraphysiologic and variable zinc concentrations observed in broth used in automated platforms and the subsequent implications for susceptibility testing of metallo-β-lactamase (MBL)-harboring isolates. This variability also hampers efforts to develop a standardized method to uniformly reduce zinc concentrations in broth and mimic physiologic zinc conditions.

IMPORTANCE Growing data on the impact of extracellular zinc concentration on metallo-β-lactamase-mediated resistance has shed light on the importance of susceptibility testing media. However, there are no studies documenting the amount of zinc in commonly utilized automated susceptibility testing (AST) platforms. This study reveals supraphysiologic zinc concentrations as well as large zinc variability among AST platforms and highlights the challenges this raises in the development of zinc-limited media.

Paradigm Shift in Antimicrobial Resistance Pattern of Bacterial Isolates during the COVID-19 Pandemic

Antimicrobial resistance (AMR) is an emerging public health problem in modern times and the current COVID-19 pandemic has further exaggerated this problem. Due to bacterial co-infection in COVID-19 cases, an irrational consumption of antibiotics has occurred during the pandemic. This study aimed to observe the COVID-19 patients hospitalized from 1 March 2019 to 31 December 2020 and to evaluate the AMR pattern of bacterial agents isolated. This was a single-center study comprising 494 bacterial isolates (blood and urine) that were obtained from patients with SARS-CoV-2 admitted to the ICU and investigated in the Department of Microbiology of a tertiary care hospital in Delhi, India. Out of the total bacterial isolates, 55.46% were gram negative and 44.53% were gram positive pathogens. Of the blood samples processed, the most common isolates were CoNS (Coagulase Negative Staphylococcus) and Staphylococcus aureus. Amongst the urinary isolates, most common pathogens were Escherichia coli and Staphylococcus aureus. A total of 60% MRSA was observed in urine and blood isolates. Up to 40% increase in AMR was observed amongst these isolates obtained during COVID-19 period compared to pre-COVID-19 times. The overuse of antibiotics gave abundant opportunity for the bacterial pathogens to gradually develop mechanisms and to acquire resistance. Since the dynamics of SARS-COV-2 are unpredictable, a compromise on hospital antibiotic policy may ultimately escalate the burden of drug resistant pathogens in hospitals. A shortage of trained staff during COVID-19 pandemic renders it impossible to maintain these records in places where the entire hospital staff is struggling to save lives. This study highlights the extensive rise in the use of antibiotics for respiratory illness due to COVID-19 compared to antibiotic use prior to COVID-19 in ICUs. The regular prescription audit followed by a constant surveillance of hospital infection control practices by the dedicated teams and training of clinicians can improve the quality of medications in the long run and help to fight the menace of AMR.

AMR in low-resource settings: Médecins Sans Frontières bridges surveillance gaps by developing a turnkey solution, the Mini-Lab

BACKGROUND

In low- and middle-income countries (LMICs), data related to antimicrobial resistance (AMR) are often inconsistently collected. Humanitarian, private and non-governmental medical organizations (NGOs), working with or in parallel to public medical systems, are sometimes present in these contexts. Yet, what is the role of NGOs in the fight against AMR, and how can they contribute to AMR data collection in contexts where reporting is scarce? How can context-adapted, high-quality clinical bacteriology be implemented in remote, challenging and underserved areas of the world?

OBJECTIVES

The aim was to provide an overview of AMR data collection challenges in LMICs and describe one initiative, the Mini-Lab project developed by Médecins Sans Frontières (MSF), that attempts to partially address them.

SOURCES

We conducted a literature review using PubMed and Google scholar databases to identify peer-reviewed research and grey literature from publicly available reports and websites.

CONTENT

We address the necessity of and difficulties related to obtaining AMR data in LMICs, as well as the role that actors outside of public medical systems can play in the collection of this information. We then describe how the Mini-Lab can provide simplified bacteriological diagnosis and AMR surveillance in challenging settings.

IMPLICATIONS

NGOs are responsible for a large amount of healthcare provision in some very low-resourced contexts. As a result, they also have a role in AMR control, including bacteriological diagnosis and the collection of AMR-related data. Actors outside the public medical system can actively contribute to implementing and adapting clinical bacteriology in LMICs and can help improve AMR surveillance and data collection.