LETITIA DOINA DUCEAC, CONSTANTIN MARCU, DANIELA LUMINITA ICHIM, IRINA MIHAELA CIOMAGA, ELENA TARCA, ALIN CONSTANTIN IORDACHE, MADALINA IRINA CIUHODARU, LAURA FLORESCU, DANA TUTUNARU, ALINA COSTINA LUCA, LIVIU STAFIE ANTIBIOTIC MOLECULES INVOLVED IN INCREASING MICROBIAL RESISTANCE Over the past two decades, the resistance to antibiotics, especially for Gram-negative bacteria, has increased at an alarming rate, requiring constant concern for resolving and controlling this extremely important therapeutic aspect in any medical department but in particular, in Anaesthesia and Intensive Care Units, in units of neonatology, paediatrics, neurosurgery, burned patients and immunosuppressed. Specialists note a particular concern for the resistance of Enterobacteriaceae to third-generation cephalosporins and aztreonam, with a resistance profile frequently associated with the expression of extended-spectrum â-lactamases (ESBL). The Enterobacter genus comprises 14 species, but two are of medical interest, Enterobacter aerogenes and E. cloacae, which are involved in inducing healthcare-associated infections such as urinary tract infections, pneumonia associated with mechanical ventilation, bacteremia, septicemia, etc. The purpose of the study was to highlight the antibiotic molecules in which microbial resistance of some circulating strains of enterobacteria was detected. A descriptive and retrospective study was conducted between 2012-2017, on a batch of 35 patients, admitted to the Sf. Maria Emergency Clinical Hospital for Children of Iasi, from whom various pathological products were collected to highlight the Enterobacter sp strains involved in the production of infections associated with the inpatient medical care. The antimicrobial sensitivity of each strain was determined by diffusimetric method, while the interpretation criteria were considered to be those of the laboratory standards. Most cases were reported in 2017 (31.42%). The majority were registered in new-borns (42.85%) and infants (25.71%). The Anaesthesia and Intensive Care Units and Neonatology Anaesthesia and Intensive Care Units departments were the most involved. Microbial antibacterial resistance of Enterobacter sp isolates showed that all manifested resistance to ampicillin, amoxicillin and clavulanic acid, 48.57% were resistant to Cefuroxime, 42.85% resistant to Ceftazidime and Ceftriaxone, 14.28% to ciprofloxacin, 11.42% to ertapenem, 5.71% to Meronem. Although it showed relatively few cases with infections associated with healthcare in which strains of Enterobacter sp. were isolated our study, which was carried out over a period of 5 years, provides useful indications regarding the prevalence of healthcare associated infections with Enterobacter sp in paediatric patients and guidelines for antibiotic therapy.