[beta-Lactam antibiotics]

New Beta-lactamases in Candidate Phyla Radiation: Owning Pleiotropic Enzymes Is a Smart Paradigm for Microorganisms with a Reduced Genome

The increased exploitation of microbial sequencing methods has shed light on the high diversity of new microorganisms named Candidate Phyla Radiation (CPR). CPR are mainly detected via 16S rRNA/metabarcoding analyses or metagenomics and are found to be abundant in all environments and present in different human microbiomes. These microbes, characterized by their symbiotic/epiparasitic lifestyle with bacteria, are directly exposed to competition with other microorganisms sharing the same ecological niche. Recently, a rich repertoire of enzymes with antibiotic resistance activity has been found in CPR genomes by using an in silico adapted screening strategy. This reservoir has shown a high prevalence of putative beta-lactamase-encoding genes. We expressed and purified five putative beta-lactamase sequences having the essential domains and functional motifs from class A and class B beta-lactamase. Their enzymatic activities were tested against various beta-lactam substrates using liquid chromatography-mass spectrometry (LC-MS) and showed some beta-lactamase activity even in the presence of a beta-lactamase inhibitor. In addition, ribonuclease activity was demonstrated against RNA that was not inhibited by sulbactam and EDTA. None of these proteins could degrade single- and double-stranded-DNA. This study is the first to express and test putative CPR beta-lactamase protein sequences in vitro. Our findings highlight that the reduced genomes of CPR members harbor sequences encoding for beta-lactamases known to be multifunction hydrolase enzymes.

Instructive Advances in Chemical Microbiology Inspired by Nature's Diverse Inventory of Molecules

Natural product antibiotics have played an essential role in the treatment of bacterial infection in addition to serving as useful tools to explore the intricate biology of bacteria. Our current arsenal of antibiotics operate through the inhibition of well-defined bacterial targets critical for replication and growth. Pathogenic bacteria effectively utilize a diversity of mechanisms that lead to acquired resistance and/or innate tolerance toward antibiotic therapies, which can result in devastating consequences to human life. Several research groups have established innovative programs that work at the chemistry-biology interface to develop new molecules that aim to define and address concerns related to antibiotic resistance and tolerance. In this Review, we present recent progress by select research groups that highlight a diversity of integrated chemical biology and medicinal chemistry approaches aimed at the development and utilization of chemical tools that have led to promising new microbiological insights that may lead to significant clinical advances regarding the treatment of pathogenic bacteria.

Antimicrobial Agents and Urinary Tract Infections

Urinary Tract Infections (UTIs); second-ranking infectious diseases are regarded as a significant global health care problem. The UTIs annually cost tens of millions of dollars for governments worldwide. The main reason behind these costs is incorrect or indefinite treatment. There are a wide range of gram-negative and grampositive bacteria which may cause UTIs in males and females, children and adults. Among gram-negative bacteria, some members of Enterobacteriaceae such as Escherichia coli (E.coli) strains have significant contribution in UTIs. Uropathogenic E.coli (UPEC) strains are recognized as typical bacterial agents for UTIs. Thus, sharp and accurate diagnostic tools are needed for detection and identification of the microbial causative agents of UTIs. In parallel with the utilization of suitable diagnostic methods-to reduce the number of UTIs, effective and definite treatment procedures are needed. Therefore, the prescription of accurate, specific and effective antibiotics and drugs may lead to a definite treatment. However, there are many cases related to UTIs which can be relapsed. Due to a diversity of opportunistic and pathogenic causative microbial agents of UTIs, the treatment procedures should be achieved by the related antimicrobial agents. In this review, common and effective antimicrobial agents which are often prescribed for UTIs caused by UPEC will be discussed. Moreover, we will have a sharp look at their (antimicrobials) molecular treatment mechanisms.

Methicillin resistance and biofilm production in clinical isolates of Staphylococcus aureus and coagulase-negative Staphylococcus in México

Introducción.

Las infecciones por Staphylococcus aureus y Staphylococcus coagulasa negativa multirresistentes a los antibióticos y asociadas con la atención en salud tienen un gran impacto epidemiológico por su alta morbimortalidad; además, se han relacionado con la formación de biopelículas, lo cual también se asocia con la resistencia a los antimicrobianos.

Objetivo.

Determinar la resistencia a la meticilina y cuantificar la producción de biopelículas para establecer su posible relación con los aislamientos clínicos de S. aureus y Staphylococcus coagulasa negativa.

Materiales y métodos.

Se estudiaron 11 cepas de S. aureus y 12 de Staphylococcus coagulasa negativa. La resistencia a la meticilina se determinó con discos de cefoxitina tomando como valores de referencia los estándares del Clinical Laboratory Standards Institute (CLSI) de 2018. La producción de biopelícula se cuantificó con cristal violeta. Los genes mecA e icaADBC se identificaron mediante reacción en cadena de la polimerasa (PCR), y se hizo un análisis bivariado con la prueba de ji al cuadrado y el coeficiente V de Cramér, utilizando el programa SPSS™, versión 20.0.

Resultados.

Nueve cepas de S. aureus fueron resistentes a la meticilina (SARM) y dos fueron sensibles. Ocho cepas de Staphylococcus coagulasa negativa fueron resistentes y cuatro fueron sensibles. El genotipo mecA se encontró en ocho de las nueve cepas de S. aureus y en seis de las ocho de Staphylococcus coagulasa negativa resistentes a meticilina. Todas las cepas formaron biopelícula. Diez cepas de S. aureus y 11 de Staphylococcus coagulasa negativa presentaron el genotipo icaADCB. No se encontró asociación entre la resistencia a meticilina y la formación de biopelícula.

Conclusiones.

La cefoxitina es suficiente para determinar el fenotipo resistente a meticilina y se asoció con el genotipo mecA. Las cepas resistentes a la meticilina y poseedoras del gen mecA pueden presentar un mecanismo de resistencia alterno. Los dos grupos de cepas formadoras de biopelícula se relacionaron con la presencia del operón icaADCB. La formación de biopelícula y la resistencia a la meticilina se expresaron como características independientes en los dos grupos de cepas.

Recent Progress in Natural-Product-Inspired Programs Aimed To Address Antibiotic Resistance and Tolerance

Bacteria utilize multiple mechanisms that enable them to gain or acquire resistance to antibiotic therapies during the treatment of infections. In addition, bacteria form biofilms which are surface-attached communities of enriched populations containing persister cells encased within a protective extracellular matrix of biomolecules, leading to chronic and recurring antibiotic-tolerant infections. Antibiotic resistance and tolerance are major global problems that require innovative therapeutic strategies to address the challenges associated with pathogenic bacteria. Historically, natural products have played a critical role in bringing new therapies to the clinic to treat life-threatening bacterial infections. This Perspective provides an overview of antibiotic resistance and tolerance and highlights recent advances (chemistry, biology, drug discovery, and development) from various research programs involved in the discovery of new antibacterial agents inspired by a diverse series of natural product antibiotics.

[Analysis of antibiotic consumption in the pediatric population of Castile and León (Spain) from 2001 to 2005]

OBJECTIVES

To analyze trends in antibiotic use among the pediatric population of Castile and León from 2001 to 2005.

MATERIAL AND METHODS

The antibiotics prescribed to the pediatric population in primary care were processed using the CONCYLIA database. The technical unit of measurement was the defined daily dose (DDD) and the comparative indicator used was the DDD per 1000 inhabitants/day (DID).

RESULTS

Overall consumption was high (21.21 DID). Throughout the 5 years of the study we observed substantial variations, especially in 2005, the year in which consumption was highest (25.05 DID). The therapeutic subgroups most frequently prescribed were wide-spectrum penicillins (8.08 DID) and penicillins associated with beta-lactamase inhibitors (7.29 DID), followed by cephalosporins (2.81 DHD) and macrolides (2.52 DHD). The percentage of wide-spectrum penicillin prescription was higher than that of penicillins associated with beta-lactamase inhibitors between 2001 and 2002. These percentages were similar in 2003, and the percentage of wide-spectrum penicillin prescription was lower than that of penicillins associated with beta-lactamase inhibitors in the last 2 years of the study.

CONCLUSIONS

Marked differences in consumption were observed over the study period. Changes in patterns of use were found, with an increase in the use of penicillins associated with beta-lactamase inhibitors in the last 2 years of the study.