[Grupo Colaborativo de Resistencia Bacteriana, Chile: recommendations 2014 towards the control of bacteria resistance]. / Grupo Colaborativo de Resistencia Bacteriana, Chile: recomendaciones 2014 para el control de la resistencia bacteriana.

Five issues were reviewed in depth at the 2014 annual meeting of Colaborative Group Against Bacterial Resistance and the antecedents and conclusions are detailed in this document. I.- News in CLSI 2014: the difficulties and implications on its implementation at the local level were reviewed and recommendations were set. II.- Criteria for determining the incidence of multi-resistant microorganism in critical care units where indicators and monitoring methodology for better quantification of microorganisms were defined. III.- Quality requirements were established to be considered by the professionals involved in the selection of antimicrobials in the hospital. IV.- Transfer policies, screening and contact precautions for the control of transmission of multiresistant bacteria. V.- Recommendations for health facilities when a carbapenemase producing enterobacteriacea is detected, in a checklist format for rapid deployment in hospitals without endemia of these agents. These are suggestions that arise from the joint work of specialists from many hospitals that do not represent consensus or recommendation, but may help to control the resistance level of each health facility in the country.

Community-acquired methicillin-resistant Staphylococcus aureus invasive infections: a case series from Central-South Chile.

The emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections at the end of the 20th century represents a significant shift in the epidemiology of staphylococcal infections and, consequently, their clinical management. There are diverse CA-MRSA clones that are widely spread worldwide, showing differences in their regional dissemination, which has been dynamically changing over time. Although the first CA-MRSA description occurred about 30 years ago, its epidemiology in certain regions, such as South America, has been poorly explored, resulting in a gap in the understanding of the epidemiology of CA-MRSA in under-represented countries/regions. This report describes the first four clinical cases of invasive infections caused by CA-MRSA in a tertiary hospital in the central-southern region of Chile. It also associates the clinical characteristics of the infections with the microbiological and molecular features of the isolates. The four S. aureus isolates belong to sequence type 8, which has been widely described as a cause of community-acquired infections. All of them presented a wide resistome and virulome. Additionally, in two of them, it was possible to reconstruct the COMER genetic element, present in the USA300-Latin American variant clone. Considering these findings, it is crucial to prepare for a potential increase in invasive CA-MRSA infections in Chile. This would involve enhancing current surveillance systems and maintaining a low threshold of suspicion for these infections among clinicians.

[The pneumococcal connection]. / La conexión neumocóccica.

The resistance of gram-negative bacilli is one of the most important areas in modern medicine, however it hasn't been highlighted the role of the third generation cephalosporins and in particularly ceftriaxone in the selection of gram-negative bacilli resistant to these agents. Paradoxically, ceftriaxone, like the rest of the molecules of this generation, whose initial indication were gram- negative infections began to be used as an agent of choice in pneumococcal infections. The broad spectrum activity of this molecule with its favorable pharmacokinetic properties replaces other agents by this antibiotic in the treatment of a wide range of community acquired infections. However, it wasn't considered the action of this cephalosporin on the microbiome, particularly the intestinal flora, which allowed the selection of enterobacteria that by genetic events, especially parental ß-lactamases mutations (TEM-1, TEM-2, SHV-1), developed resistance to third-generation cephalosporins. The decreased susceptibility to penicillin in Streptococcus pneumoniae isolates that stimulated the growing use of ceftriaxone, was one of the main drivers for the development of resistance to third-generation cephalosporins in gram-negative bacilli.

[Copper activity against multiresistant Gram negative bacilli isolated from Chilean hospitals]. / Actividad de cobre sobre bacilos gramnegativos multi-resistentes aislados en hospitales chilenos.

INTRODUCTION: Multiresistant nosocomial pathogens, especially Gram-negative bacilli (GNB), are a serious problem for public health systems worldwide. Due to their antimicrobial properties, copper alloys have been suggested as an alternative for the control of bacterial burden in surfaces in hospital environment. However, antibiotic multiresistance and copper resistance could be associated in GNB, and there is evidence that both kind of resistance genes (antibiotic and copper) can be located on the same genetic structures. For this reason antibiotic-multiresistant strains could survive in the presence of copper, selecting for bacterial phenotypes resistant to both antibacterial agents. AIM: To evaluate antibacterial activity of copper against nosocomial extended-spectrum ß-lactamases (ESBL) (+) and ESBL (-) GNB, and carbapenems resistant or susceptible strains. MATERIAL AND METHOD: This study included 390 strains of GNB isolated from Chilean hospitals: Acinetobacter baumannii and Pseudomonas aeruginosa resistant (CAR R) and susceptible (CAR S) to carbapenem antibiotics, and Klebsiella pneumoniae and Escherichia coli producers and non-producers of ESBL. Susceptibility levels to cupric sulphate were determined by agar dilution method and statistical analysis were used to determine the significance of the differences in the copper tolerance levels between the strains groups. RESULTS: Statistically superior copper tolerance levels were found in the CAR R and ESBL producing strains of A. baumannii and K. pneumoniae, in relation with the CAR S and ESBL not-producing strains. CONCLUSION: A relation between a diminished susceptibility to ionic copper and to recent generation antimicrobial agents was observed in K. pneumoniae y A. baumannii strains.

Novel Megaplasmid Driving NDM-1-Mediated Carbapenem Resistance in Klebsiella pneumoniae ST1588 in South America.

Carbapenem-resistant Enterobacterales (CRE) is a critical public health problem in South America, where the prevalence of NDM metallo-betalactamases has increased substantially in recent years. In this study, we used whole genome sequencing to characterize a multidrug-resistant (MDR) Klebsiella pneumoniae (UCO-361 strain) clinical isolate from a teaching hospital in Chile. Using long-read (Nanopore) and short-read (Illumina) sequence data, we identified a novel un-typeable megaplasmid (314,976 kb, pNDM-1_UCO-361) carrying the blaNDM-1 carbapenem resistance gene within a Tn3000 transposon. Strikingly, conjugal transfer of pNDM-1_UCO-361 plasmid only occurs at low temperatures with a high frequency of 4.3 × 10-6 transconjugants/receptors at 27 °C. UCO-361 belonged to the ST1588 clone, previously identified in Latin America, and harbored aminoglycoside, extended-spectrum ß-lactamases (ESBLs), carbapenem, and quinolone-resistance determinants. These findings suggest that blaNDM-1-bearing megaplasmids can be adapted to carriage by some K. pneumoniae lineages, whereas its conjugation at low temperatures could contribute to rapid dissemination at the human-environmental interface.

[Molecular basis of methicillin-resistance in Staphylococcus aureus]. / Bases moleculares de la resistencia a meticilina en Staphylococcus aureus.

Staphylococcus aureus isolates resistant to several antimicrobials have been gradually emerged since the beginning of the antibiotic era. Consequently, the first isolation of methicillin-resistant S. aureus occurred in 1960, which was described a few years later in Chile. Currently, S. aureus resistant to antistaphylococcal penicillins is endemic in Chilean hospitals and worldwide, being responsible for a high burden of morbidity and mortality. This resistance is mediated by the expression of a new transpeptidase, named PBP2a or PBP2', which possesses lower affinity for the ß-lactam antibiotics, allowing the synthesis of peptidoglycan even in presence of these antimicrobial agents. This new enzyme is encoded by the mecA gene, itself embedded in a chromosomal cassette displaying a genomic island structure, of which there are several types and subtypes. Methicillin resistance is mainly regulated by an induction mechanism activated in the presence of ß-lactams, through a membrane receptor and a repressor of the gene expression. Although mec-independent methicillin resistance mechanisms have been described, they are clearly infrequent.

[Antiseptics and disinfectants: aiming at rational use. Recommendations of the Advisory Committee on Healthcare Associated Infections. Sociedad Chilena de Infectología]. / Antisépticos y desinfectantes: apuntando al uso racional. Recomendaciones del Comité Consultivo de Infecciones Asociadas a la Atención de Salud, Sociedad Chilena de Infectología.

Proper use of antiseptics and disinfectants, is an essential tool to prevent the spread of infectious agents and to control of healthcare-associated infections (HAI). Given the increasing importance of environmental aspects, as well as several advances and updates in the field of its proper use at local and intemational level, the SOCHINF HAI Advisory Committee considers that it is necessary to develop a guide for the rational use of antiseptics and disinfectants, which it will provide consistent scientific basis with that purpose.

[Colistin in the post-antibiotic era]. / Colistín en la era post-antibiótica.

One of the most important features of the post-antibiotic era in the late 20th century is the resurgence of colistin for the treatment of extensively drug resistant gram-negative bacteria (XDR). Colistin is a narrow spectrum anti-biotic, active against microorganisms with clinical significance such as Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae. Nowadays its toxicity is lower, partly explained by better pharmaceuticals and management of the critically ill patients. However, there has been much confusion regarding the dosage of the drug, its name and labeling, therefore, experts have recommended using a common language about this polymyxin. The lack of PK/PD studies for colistin is perhaps the main weakness of this area of knowledge, even though the before mentioned approach has contributed with new ways to manage and calculate the dose of this antimicrobial. Indeed, the efficiency of colistin in association with a second agent in reducing mortality has not been demonstrated.