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Antimicrobial resistance, the challenge of infectious diseases

The inappropriate and indiscriminate use of antibiotics, and therefore their resistance, leads to therapeutic failures, greater mortality rates, and high hospital costs, among others. Scientists predict that for 2050 this will be the main cause of death above cancer, diabetes, and heart disease.

“Treating this effectively implies teaching the community to avoid the inadequate use of antibiotics, and for science to control the emergency of tolerant microorganisms or to extend the therapeutic proposals,” said Universidad Nacional de Colombia (UNal) Sciences-Microbiology M. Sc. and researcher Mónica Liliana Vargas Ardila.

Her research, “Exploring the genetic features linked to the development of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) in methicillin-resistant Staphylococcus aureus (MRSA) isolates, causing agents of bacteremia,” was highlighted during the UNAL Radio Program, Respuestas por Escrito (Written Responses) (98.5 FM.)

Staphylococcus aureus is an important pathogen that causes an ample range of infections both mild and severe, such as endocarditis. Despite this group of bacteria being amply known for causing infections in humans for more than a century, it continues to be a challenge for clinicians and scientists, given its high versatility.

On its part, “heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA) isolates are a clinical and epidemiological challenge, as they are associated to therapeutic failures and long hospital stays, and it is not detectable by standard methodologies and the genetic mechanism is not completely understood.”

The use of microbial agents is the main media to battle serious infectious diseases, as until now, it hasn’t been possible to develop an effective vaccine.

The developed research emphasizes that this pathogen quickly turned resistant to penicillin, after being introduced to clinical practice in 1940. In 1961, it showed resistance to semi-synthetic penicillins and most antibiotics used later as treatment.

“Despite the complete characterization of a microorganism in a laboratory is a costly and slow, the use of new generation sequencing technologies has allowed sequencing a high number of bacterial genomes in a short time. This has helped in the understanding of features, not only genetic but also allowed analyzing them from different health scopes,” said Vargas.

Realization of the project and results


Vargas explains that between 2011 and 2014 they took hVISA phenotype tests in different hospitals in 9 Latin American countries such as Argentina, Chile, Colombia, Brazil, Ecuador, México, Perú, and Venezuela. They were previously studied at the Antimicrobial Resistance and Genetics Unit of the Colombian Universidad El Bosque.

During the research project, they identified 538 isolates, of which 30 had a positive result for hVISA through Etest based methods, which were analyzed and characterized during the research,” she said.

One of the most important findings is that they discovered changes previously reported and not reported associated with alterations in regulating system functions, cell wall biogenesis, RNA, DNA procedures, and membrane biosynthesis.

“The 30 isolates showed resistance determinants belonging to different families, showing a multi-resistance profile and they also discovered 90 amino acid substitutions,” said Vargas


Finally, she recommended continuing the antimicrobial resistance epidemiological surveillance and infections caused by MRSA isolates in the region and suggested establishing stricter regulations for Latin-American countries for the use of antibiotics.

Consejo Editorial