The objectives of this study were to determine the kinetic parameters of purified recombinant Bla and Bla by spectrophotometry, analyze the genetic environment of the bla and bla genes in both species by polymerase chain reaction and sequencing, furthermore, in silico models of both enzymes in complex with imipenem were obtained by modeling tools. Our results showed that Bla and Bla have a similar hydrolysis behavior, displaying high catalytic efficiencies toward penams, cephalothin, and nitrocefin; none of the enzymes are well inhibited by clavulanate. Bla hydrolyzes imipenem at higher efficiency than cefotaxime and aztreonam. Bla and Bla showed that their closest structural homologs are KPC-2 and SFC-1, which correlate to the mild carbapenemase activity toward imipenem observed at least for BlaMmas. They also seem to differ from other class A β-lactamases by the presence of a more flexible Ω loop, which could impact in the hydrolysis efficiency against some antibiotics. A -35 consensus sequence (TCGACA) and embedded at the 3' end of MAB_2874, which may constitute the bla and bla promoter. Our results suggest that the resistance mechanisms in fast-growing mycobacteria could be probably evolving toward the production of β-lactamases that have improved catalytic efficiencies against some of the drugs commonly used for the treatment of mycobacterial infections, endangering the use of important drugs like the carbapenems.

No abstract

The Enterobacter cloacae complex is an emerging opportunistic pathogen whose increased resistance to carbapenems is considered a public health problem. This is due to the loss of efficacy of beta-lactam antibiotics, which are used as the first treatment option in the management of infections caused by Gram-negative bacteria. The objective of this study was to perform the molecular characterization of 28 isolates of the E. cloacae complex resistant to cephalosporins and carbapenems isolated between 2011 and 2018 from five hospitals located in the municipality of Santiago de Cali, Colombia. Molecular detection of blaKPC, blaVIM, blaNDM and blaOXA-48-like genes was performed on these isolates and the genetic relationship between the isolates was assessed using multilocus sequence typing (MLST). Forty-three percent of the isolates carried the blaKPC-2 gene variant. MLST showed high genetic diversity among isolates, the most frequent being the sequence type ST510 with a frequency of 50%. The identification of the genes involved in carbapenem resistance and dispersing genotypes is an important step toward the development of effective prevention and epidemiological surveillance strategies in Colombian hospitals.

Bacteriophages offer an alternative for the treatment of multidrug-resistant bacterial diseases as their mechanism of action differs from that of antibiotics. However, their application in the clinical field is limited to specific cases of patients with few or no other alternative therapies. This systematic review assesses the effectiveness and safety of phage therapy against multidrug-resistant bacteria through the evaluation of studies published over the past decade. To that end, a bibliographic search was carried out in the PubMed, Science Direct, and Google Scholar databases. Of the 1500 studies found, 27 met the inclusion criteria, with a total of 165 treated patients. Treatment effectiveness, defined as the reduction in or elimination of the bacterial load, was 85%. Except for two patients who died from causes unrelated to phage therapy, no serious adverse events were reported. This shows that phage therapy could be an alternative treatment for patients with infections associated with multidrug-resistant bacteria. However, owing to the phage specificity required for the treatment of various bacterial strains, this therapy must be personalized in terms of bacteriophage type, route of administration, and dosage.

Global control and elimination of tuberculosis are hindered by the high prevalence of drug-resistant strains, making the development of new drugs to fight tuberculosis a public health priority. In this study, we evaluated 118 extracts from 58 Venezuelan plant species for their ability to inhibit the growth of Mycobacterium tuberculosis mc26020, using the agar dilution method. Additionally, we determined the ability of these extracts to inhibit the activity of PknB protein, an essential M. tuberculosis serine/threonine kinase, using a high-throughput luminescent assay. Of the 118 extracts tested, 14 inhibited bacterial growth with a minimum inhibitory concentration ≤500 μg/ml, and 36 inhibited the kinase activity with a half-maximal inhibitory concentration <200 μg/ml. Five extracts inhibited M. tuberculosis growth and inhibited the activity of the kinase protein, suggesting that this could be the basis of their growth inhibition.

Fluoroquinolones (FQs) are antibiotics useful in the treatment of drug-resistant tuberculosis, but FQ-resistant mutants can be selected rapidly. Although mutations in the DNA gyrase are the principal cause of this resistance, pentapeptide proteins have been found to confer low-level FQ resistance in Gram-negative bacteria. MfpA is a pentapeptide repeat protein conserved in mycobacterial chromosomes, where it is adjacent to a group of four highly conserved genes termed a conservon. We wished to characterize the transcriptional regulation of the mfpA gene and relate its expression to ciprofloxacin resistance in M. smegmatis. Reverse transcription PCR showed that mfpA gene is part of an operon containing the conservon genes. Using a transcriptional fusion, we showed that a promoter was located 5′ to the mfpEA operon. We determined the promoter activity under different growth conditions and found that the expression of the operon increases slightly in late growth phases in basic pH and in subinhibitory concentrations of ciprofloxacin. Finally, by cloning the mfpA gene in an inducible vector, we showed that induced expression of mfpA increases the ciprofloxacin Minimal Inhibitory Concentration. These results confirm that increased expression of the mfpA gene, which is part of the mfpEA operon, increases ciprofloxacin resistance in M. smegmatis.

<p> Los carbapenems son antibióticos â-lactamicos de amplio espectro que se utilizan como terapia de primera línea para tratar pacientes con infecciones graves. Actualmente, la resistencia a carbapenems se asocia con la presencia de â-lactamasas capaces de hidrolizar estos antibióticos. La carbapenemasa de clase A más común es KPC, la cual es codificada por el gen <em>bla</em>KPC que generalmente, se encuentra ubicado en plásmidos. La selección y la rápida propagación de aislados de <em>Klebsiella pneumoniae </em>portadores de estas carbapenemasas se ha convertido en un problema de salud pública a nivel mundial. Esta mini-revision describe uno de los mecanismos más frecuentes de resistencia a carbapenems como lo son las enzimas carbapenemasas tipo KPC. Además se describen las variantes del gen <em>bla</em>KPC asi como el elemento genético móvil, el transposon <em>Tn</em>4401, el principal responsable de su diseminación entre géneros y especies bacterianas diferentes. Finalmente se hace una pequeña revisión cronológica de los reportes de la enzima KPC a nivel mundial.</p>

Los Grupos de Investigación en Química y Biotecnología (QUIBIO) y Microbiología Industrial y Medio Ambiente (GIMIA) hacen parte del Centro de Estudios e Investigaciones en Ciencias Básicas Ambientales y Desarrollo Tecnológico (CICBA), adscrito a la Facultad de Ciencias Básicas de la Universidad Santiago de Cali. Desde su nacimiento el CICBA, a propendido por estar a la vanguardia al interior de la Universidad en la investigación, conciencia por el medio ambiente y desarrollo tecnológico. Los grupos de investigación acordes con esta macrolinea, se han preocupado por aportar sus desarrollos investigativos y de innovación en un marco de responsabilidad social, es así como en este libro de investigación titulado “LA CONTAMINACIÓN INDUSTRIAL DE AGUAS: Una Mirada Microbiológica y Molecular” se recopilan 4 trabajos de investigadores pertenecientes a los dos grupos de investigación con el fin de dar a conocer estudios realizados en Colombia y Venezuela sobre la problemática de la contaminación en cuerpos acuíferos.