News Update on Antimicrobial Resistance Research: Jan – 2020

Mechanisms of Antimicrobial Resistance in Bacteria

The treatment of bacterial infections is increasingly complicated by the power of bacteria to develop resistance to antimicrobial agents. Antimicrobial agents are often categorized consistent with their principal mechanism of action. Mechanisms include interference with cell membrane synthesis (e.g., β-lactams and glycopeptide agents), inhibition of protein synthesis (macrolides and tetracyclines), interference with macromolecule synthesis (fluoroquinolones and rifampin), inhibition of a metabolic pathway (trimethoprim-sulfamethoxazole), and disruption of bacterial membrane structure (polymyxins and daptomycin). Bacteria could also be intrinsically immune to ≥1 class of antimicrobial agents, or may acquire resistance by de novo mutation or via the acquisition of resistance genes from other organisms. [1]

Identification of acquired antimicrobial resistance genes

Objectives: Identification of antimicrobial resistance genes is vital for understanding the underlying mechanisms and therefore the epidemiology of antimicrobial resistance. because the costs of whole-genome sequencing (WGS) still decline, it becomes increasingly available in routine diagnostic laboratories and is anticipated to substitute traditional methods for resistance gene identification. Thus, the present challenge is to extract the relevant information from the massive amount of generated data.

Methods: We developed a web-based method, ResFinder that uses BLAST for identification of acquired antimicrobial resistance genes in whole-genome data. As input, the tactic can use both pre-assembled, complete or partial genomes, and short sequence reads from four different sequencing platforms. the tactic was evaluated on 1862 GenBank files containing 1411 different resistance genes, also as on 23 de-novo-sequenced isolates. [2]

Antimicrobial resistance: the example of Staphylococcus aureus

In the early 1970s, physicians were finally forced to abandon their belief that, given the vast array of effective antimicrobial agents, virtually all bacterial infections were treatable. Their optimism was shaken by the emergence of resistance to multiple antibiotics among such pathogens as Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and tubercle bacillus . The evolution of increasingly antimicrobial-resistant bacterial species stems from a mess of things that has the widespread and sometimes inappropriate use of antimicrobials, the extensive use of those agents as growth enhancers in animal feed, and, with the rise in regional and international travel, the relative ease with which antimicrobial-resistant bacteria cross geographic barriers (1–3). [3]

Sequencing-based methods and resources to study antimicrobial resistance

Antimicrobial resistance extracts high morbidity, mortality and economic costs yearly by rendering bacteria resistant to antibiotics. Identifying and understanding antimicrobial resistance are imperative for clinical practice to treat resistant infections and for public health efforts to limit the spread of resistance. Technologies like next-generation sequencing are expanding our abilities to detect and study antimicrobial resistance. This Review provides an in depth overview of antimicrobial resistance identification and characterization methods, from traditional antimicrobial susceptibility testing to recent deep-learning methods. [4]

Antimicrobial Resistance and Detection of Biofilm in Staphylococcus aureus Isolates from Casablanca

Aims: the power of biofilm formation seems to play an important role within the virulence of Staphylococcus aureus. The aims of this study were to check the sensitivity of the clinical isolates of Staphylococcus aureus to antibiotics, detect the power of those strains to make biofilm and evaluate the correlation between biofilm formation by clinical isolates and therefore the resistance to antibiotics.

Place and Duration of Study: Laboratory of Virology, Microbiology and Quality/ Eco-toxicology and Biodiversity, Faculty of Sciences and Techniques Mohammedia, University Hassan II Casablanca and laboratory of Bacteriology, Virology and Hygiene, Ibn Rochd University Hospital, Casablanca during October 2015 and January 2016. [5]


[1] Tenover, F.C., 2006. Mechanisms of antimicrobial resistance in bacteria. The American journal of medicine, 119(6), (Web Link)

[2] Zankari, E., Hasman, H., Cosentino, S., Vestergaard, M., Rasmussen, S., Lund, O., Aarestrup, F.M. and Larsen, M.V., 2012. Identification of acquired antimicrobial resistance genes. Journal of antimicrobial chemotherapy, 67(11), (Web Link)

[3] Lowy, F.D., 2003. Antimicrobial resistance: the example of Staphylococcus aureus. The Journal of clinical investigation, 111(9), (Web Link)

[4] Sequencing-based methods and resources to study antimicrobial resistance
Manish Boolchandani, Alaric W. D’Souza & Gautam Dantas
Nature Reviews Genetics volume 20, (Web Link)

[5] Achmit, M., Rehhali, M., Chouati, T., Katfy, K., Mellouki, F., Zerouali, K., Ait Mhand, R. and Rhallabi, N. (2017) “Antimicrobial Resistance and Detection of Biofilm in Staphylococcus aureus Isolates from Casablanca”, Biotechnology Journal International, 17(3), (Web Link)

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