Bacilos Gram-negativos no ambiente de uma unidade de terapia intensiva: ocorrência, resistência a antimicrobianos e análise molecular

Abstract

Contamination of the surfaces and the air from hospital environment is related to multirresistant (MDR) pathogens transmission, specially Gram-negative bacteria producing carbapenemases, wich represents an obstacle to the treatment and control of infections. This study evaluated the occurrence, the susceptibility to antimicrobial compounds and the presence of resistance genes from Gram-negative bacilli (GNB) isolated from the ICU of a university hospital. Between January and July of 2012, six air and surfaces samplings were conducted at selected sites from the ICU s environment. The GNB samples were identified through phenotypic and molecular techniques, Antibiotic susceptibility was determined by disc diffusion and the presence of extended spectrum β-lactamase (ESBL) genes (TEM, CTX) and carbapenemases genes (OXA, KPC) was studied by PCR. Non fermenters Gram-negative bacilli (NFGNB) were predominant at the air samples, notably occurring OXA-51 and OXA-23 Acinetobacter baumannii producers. KPC and ESBL positive K. pneumoniae and ESBL positive K. pneumoniae and Enterobacter cloacae Complex (ECC) were also isolated from the ICU air. The number of NFGNB and enterobacteria isolated from the surfaces was similar, with the presence of both A. baumannii and P. aeruginosa MDR, as well as KPC and ESBL producers K. pneumonie and ECC . The genome of an airborne and antibiotic susceptible Acinetobacter non-baumannii (Anb) carrying blaOXA-58 was sequenced. Several genes related to antibiotics and heavy metals resistance, virulence, persistence and mobile elements were found that may have contributed to its survival at the hospital environment, where this strain may be acting as a resistance reservoir. Microdillution for antibiotis and metals was performed and the strain was was resistant only to arsenic (MIC≥ 2048µg/mL) and copper (MIC= 256µg/mL). The methodologies applied for identification of species trough genome comparison and proteins profile (ANI, snpTree e MALDI-TOF MS) indicated that this strain represents a new species of Acinetobacter. The presence of MDR microrganisms at the hospital environment points out to the relevance of surface contamination and air transmition for infection control. The knowledge about Anb is highly important, as it may reveal resistance genes reservoirs and helps to elucidate resistance genes, inside and outside of the hospital environment.