Pseudomonas Aeruginosa: Virulence Factors and Antibiotic Resistance Genes

Abstract In this review, we explore some aspects of Pseudomonas aeruginosa virulence factors that are related to disease development in healthy organisms and resistance to antibiotics. This pathogen is one of the most clinically and epidemiologically important bacteria in Brazil, being the major cause of opportunistic infections. Among the virulence factors, biofilm formation acting of manner different in the organism. Furthermore, we review several P. aeruginosa genes that act in antimicrobial resistance, such as β-lactamases against β-lactamers. The resistance to pied-lactamases in P. aeruginosa is associated to resistance to the broad-spectrum cephalosporin. On the other hand, there is a group of synthetic broad-spectrum antibiotics acting on DNA synthesis is the quinolones that destroy the microorganism. We also explore the occurence of super bacterium: P. aerufinosa carrying genes blaKPC and blaNDM, which are associated with patient death above the average of other bacterial infections in hospitals. Those genes encode carbapenemases that can potentially hydrolyse all β-lactam antibiotics

Multirresistencia y factores asociados a la presencia de betalactamasas de espectro extendido en cepas de Escherichia coli provenientes de urocultivos / Multiresistance and factors associated with the presence of extended-spectrum beta-lactamases in Escherichia coli strains isolated from urine culture

RESUMEN El tratamiento empírico para la infección urinaria se ve complicado frente a la presencia de multirresistencia y de betalactamasas de espectro extendido (BLEE). El objetivo del estudio fue describir los patrones de resistencia antibiótica de cepas de Escherichia coli aisladas en urocultivos y los factores clínico-epidemiológicos asociados a la presencia de BLEE en un grupo pediátrico y adulto. Se recolectaron durante 14 meses, 353 cepas provenientes de Emergencia y Hospitalización del Hospital Cayetano Heredia, 45,9% fueron cepas multirresistentes. La incidencia de BLEE en población pediátrica fue 16,3% vs. 31,1% en la adulta, el 63,6% provenía de pacientes ambulatorios. La presencia de BLEE se asoció con encontrarse hospitalizado en pediatría, así cómo al uso de pañal y vejiga neurogénica en adultos. Estos factores deben considerarse al momento de elegir un tratamiento antibiótico. Asimismo, es necesario implementar programas de reporte epidemiológico y modelos de prevención de factores de riesgo.

ABSTRACT The empirical treatment of urinary infections is complicated by the presence of multiresistance and resistance to extendedspectrum beta-lactamases (ESBLs). The objective of this study was to describe the patterns of antibiotic resistance of Escherichia coli strains isolated from urine cultures and the clinical-epidemiological factors associated with the presence of ESBLs in a pediatric and an adult group. A total of 353 strains were collected from the Emergency and Hospitalization Sector of the Cayetano Heredia Hospital over 14 months, and 45.9% of the isolated strains were multiresistant. The rate of resistance to ESBLs in the pediatric and adult population was 16.3% and 31.1%, respectively, and 63.6% of the resistant strains were isolated from outpatients. The presence of ESBLs was associated with hospitalization in pediatrics, use of diapers, and the presence of neurogenic bladder in adults. These factors should be considered in selection of an antibiotic treatment. Moreover, epidemiological reporting programs and models should be implemented for reduction of risk factors.

Genes blaTEM, blaSHV y blaCTX-M en enterobacterias productoras de b-lactamasas de espectro extendido aisladas de pacientes con infección intrahospitalaria / blaTEM, blaSHV y blaCTX-M genes in extended-spectrum b-lactamases producing enterobacterias isolated from patients with hospital-acquired infections

El objetivo de este estudio fue identificar los genes blaTEM, blaSHV y blaCTX-M en aislados clínicos de enterobacterias productoras de b-lactamasas de espectro extendido (BLEE), recolectadas entre septiembre y noviembre de 2005. Además de la resistencia a las cefalosporinas de tercera generación, los aislados también mostraron resistencia a cloranfenicol (59,2%) amikacina (37,0%) y gentamicina (40,7%) y se mostraron sensibles a imipenem y meropenem. Nueve cepas lograron transferir la resistencia a las cefalosporinas de tercera generación, así como la producción de BLEE. En los aislados clínicos se detectaron los genes blaSHV, blaTEM y blaCTX-M, donde los tipos blaTEM-1, blaSHV-1, blaSHV-5 blaSHV-5-2a y blaCTX-M-1 fueron los prevalentes; mientras que en las transconjugantes sólo se detectaron blaTEM-1, blaSHV-5 y blaSHV-5-2a. Se identificaron en total siete tipos de genes, de los cuales cinco eran codificantes de enzimas tipo BLEE, lo que demuestra que en el centro hospitalario la resistencia a las cefalosporinas de tercera generación es debida a diversas enzimas.

The objective of the present investigation was to identify the blaTEM, blaSHV and blaCTX-M genes on extended-spectrum b-lactamases (ESBL) producing Enterobacteriaceae from clinical isolates, collected between September and November 2005. In addition to third-generation cephalosporin resistance, the isolates also showed resistance to chloramphenicol (59.2%), amikacin (37.0%) and gentamicin (40.7%), and demonstrated sensitivity to imipenem and meropenem. Nine strains were capable of transferring third-generation cephalosporin resistance, as well as the production of ESBL. In the clinical isolates, the genes blaSHV, blaTEM and blaCTX-M were detected, being more prevalent the types blaTEM-1, blaSHV-1, blaSHV-5 blaSHV-5-2a and blaCTX-M-1; while in the trans-conjugated only blaTEM-1, blaSHV-5 y blaSHV-5-2a were found. In total, seven types of genes were identified, five of which were codifying genes for ESBL-type enzymes. This demonstrates that in the hospital center, resistance to third-generation cephalosporin is mediated by several enzymes.

Resistencia a los antibacterianos en América Latina: consecuencias para la infectología / Antibacterial drug resistance in Latin America: consequences for infectiousdisease control

Antibacterial drug resistance is a particularly significant issue in Latin America. This article explores antimicrobial resistance in three classes of clinically important bacteria: gram-positive bacteria, enterobacteria, and nonfermenting gram-negativebacilli. The gram-positive bacteria frequently responsible for infections in humans are for the most part cocci: staphylococci, streptococci (including pneumococci), and enterococci,in both community and hospital settings. This situation is no different in theRegion of the Americas. Among the gram-positive bacteria, the causative agents of bacteremia are most commonly strains of coagulase-negative Staphylococcus, followed by enterococci. This report explores the resistance of these species to different antimicrobial drugs, resistance mechanisms in community and hospital strains, and new drugs for treating infections caused by these bacteria. In Latin America, antimicrobialresistance in Enterococcus strains is still a minor problem compared to the situation in the United States. The strains of the genus Streptococcus isolated from respiratory infections are still sensitive to penicillin. Furthermore, the resistance of enterobacteriais extremely important in the Region, particularly because of the broad dissemination of CTX-M extended-spectrum beta-lactamases (ESBL), some of which originated in Latin America. This article analyzes the resistance of Streptococcus pneumoniae, betahemolytic streptococci, and viridans group streptococci. Among the nonfermentinggram-negative bacilli, while Pseudomonas aeruginosa strains remain the leading cause of bacteremia, infections caused by strains of Acinetobacter spp. have proliferatedextensively in some areas. With regard to antibiotics, several options are available for treating gram-positive bacterial infections...

La resistencia a los fármacos antibacterianos tiene particular importancia en América Latina. En este artículo se analiza la resistencia a los antimicrobianos de tres clases de bacterias de importancia clínica: bacterias grampositivas, enterobacterias y bacilos gramnegativos no fermentadores.Las bacterias grampositivas que producen infecciones humanas frecuentes son, en su mayoría, cocos: estafilococos, estreptococos (incluidos neumococos) y enterococos, tanto en elmedio comunitario como en el nosocomial. Esta situación no es diferente en la Región de las Américas. Entre las bacterias grampositivas, las que causan bacteriemia con mayor frecuencia corresponden a cepas de estafilococos coagulasa negativos, seguidas de las de enterococos. Eneste informe se analiza la resistencia de estas especies a distintos antimicrobianos, los mecanismosde resistencia para las cepas de origen hospitalario y comunitario y los nuevos medicamentos para tratar las infecciones por estas bacterias. La resistencia a los antimicrobianos delas cepas de Enterococcus en América Latina todavía es un problema menor en relación con la situación en los Estados Unidos de América. Las cepas del género Streptococcus aisladasde infecciones respiratorias aún son sensibles a penicilina. Por otra parte, la resistencia de las enterobacterias es de gran importancia en la Región, particularmente por la gran difusión debetalactamasas de espectro extendido (BLEE) de tipo CTX-M, algunas de las cuales se originaron en América Latina. En el presente artículo se analizan la situación de la resistencia de las cepas de Streptococcus pneumoniae, y de los estreptococos betahemolítico y del grupo viridans. Entre los bacilos gramnegativos no fermentadores, si bien las cepas de Pseudomonasaeruginosa siguen siendo la causa principal de bacteriemias, la proliferación de infecciones por cepas de Acinetobacter spp. tiene en algunas partes gran magnitud...

Resistencia a carbapenemes en aislamientos de pseudomonas aeruginosa: un ejemplo de interacción entre distintos mecanismos / Carbapenem resistance in pseudomonas aeruginosa isolates: an example of interaction between different mechanisms

Objetivo. Identificar la proteína de membrana externa ausente en los aislamientos resistentes y determinar tanto las causas de su ausencia en la membrana, como la presencia de otros mecanismos de resistencia a carbapenemes en aislamientos clínicos de Pseudomonas aeruginosa. Métodos. Se estudió un brote de 20 aislamientos de P. aeruginosa previamente caracterizados como productores de la metalobetalactamasa IMP-13. Estos aislamientos presentaron igual expresión de la enzima IMP-13, pero solo cinco de ellos fueron resistentes acarbapenemes. En esos cinco aislamientos resistentes se confirmó la ausencia de una proteína de membrana externa. Se secuenciaron oprD y ampC; se identificaron las proteínas de membrana externa por desorción/ionización láser asistida por matriz/espectometría de masa tiempo de vuelo (MALDI-TOF); se determinó el nivel de expresión de OprD, de AmpC y de los sistemas de eflujo tipo Mex, por reacción en cadena de polimerasa en tiempo real, y por último, se determinó la contribución del déficit de OprD a la resistencia a carbapenemes. Resultados. La proteína de la membrana externa ausente en el grupo R (resistentes a ambos carbapenemes) fue identificada como OprD-TS, pero no se observaron variaciones en suexpresión. El gen oprD presentó mutaciones en los cinco aislamientos resistentes. Se observó la misma producción de la enzima tipo AmpC PDC-5 y del sistema de eflujo Mex AB-OprM entre los aislamientos sensibles y resistentes a carbapenemes. Se analizó cómo la presencia conjunta de IMP-13 y el déficit de OprD contribuyen al aumento de la resistencia.Conclusiones. Distintos mecanismos contribuyen a la resistencia de aislamientos productores de IMP-13 a carbapenemes. La posibilidad de no detectar estos aislamientos productores de IMP-13 representa un riesgo latente de selección de mutantes con mecanismos de resistencia que se suman para aumentar la resistencia a carbapenemes.

Objective. To identify the outer membrane protein absent in the resistant isolates and to determine both the causes of its absence in the membrane and the presence of othermechanisms of carbapenem resistance in clinical isolates of Pseudomonas aeruginosa. Methods. Twenty isolates from an outbreak of P. aeruginosa previously characterized as metallo-beta-lactamase IMP-13 producers were studied. All the isolates exhibitedequal expression of the IMP-13 enzyme, but only five of them were carbapenemresistant. It was found that the five resistant isolates lacked a outer membrane protein. The oprD and ampC genes were sequenced; the outer membrane proteins were identifiedusing matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry; the OprD and AmpC expressions, as well as the Mex efflux system, were assessed by real-time polymerase chain reaction; and finally, the contribution of reduced OprD to carbapenem resistance was determined. Results. The absent outer membrane protein in group R was identified as OprD-TS; however, no variations in its expression were observed. The oprD gene presentedmutations in the five resistant isolates. The production of AmpC PDC-5-type enzyme and the MexAB-OprM efflux system was the same in both carbapenem-sensitive and‑resistant isolates. The contribution of the combined presence of IMP-13 and reducedOprD to increased resistance was examined. Conclusions. Different mechanisms contribute to carbapenem resistance in IMP-13-producing isolates. The possibility that these IMP-13-producing isolates could go undetected poses a latent risk when selecting mutants with added resistancemechanisms in order to enhance carbapenem resistance.

Properties of ß-lactamase from Neisseria gonorrhoeae

ß-lactamase activity was studied in Neisseria gonorrhoeae strains. Optimum temperature was found to be 37ºC. The enzyme was inactivated at temperature higher than 60ºC, but remained active during storage at low temperatures (4ºC, -30ºC and -70ºC) for two months. Enzyme activity was observed within a pH range of 5.8-8.0, while the optimum pH was 7.0-7.2. Addition of Ni²+, Fe²+, Fe cube number +, Mn²+ and p-chloromercurybenzoate to the reaction buffer exerced a negative effect upon the activity, whereas Hg²+ and ethylene diamine tetra-acetic acid produced complete inhibition. These results would indicate the presence of -SH groups at the catalytic site of the enzyme.

Factors affecting beta-lactamase production by bacillus cereus

Batch shake cultures of Bacillus cereus grown in tryptic soy broth medium gave the highest beta-lactamase activities, [Intracellular, [ICL] 2.34; Extracellular [ECL], 2.39; Cell-bound [CL], 1.56 m mol/ min /ml] as well as protein content [Intracellular proteins, [ICP], 5.77; Extracellular proteins [ECP], 8.88; Cell-bound proteins [CP], 2.61 mg/ml and biomass [600 mg/ml medium] after an incubation period of 48 hr. at 30 °C and pH 7.3. Sodium salts of different organic acids had varying influences on the fermentation yields. Sulphur containing compounds and EDTA greatly repressed the fermentation yields, key words: beta-lactamase activities, Intracellular [ICL], Extracellular [ECL], Cell-bound [CL]; protein content, Intracellular proteins, [ICP], Extracellular proteins [ECP], Cell-bound proteins [CP]