Acinetobacter spp. as nosocomial pathogens: epidemiology and resistance features

Abstract

Introduction. Acinetobacter baumannii infections are a growing clinical problem affecting all countries of the world. Given the distinct survival ability, Acinetobacter baumannii is easily spread in the hospital environment causing nosocomial infections. The risk factors for A. baumannii infection include hospitalisation, poor overall condition, circulatory system insufficiency, respiratory system insufficiency, mechanical ventilation, prior antibiotic therapy and presence of foreign materials (such as venous, arterial and urinary catheters). More than 30% of hospital-acquired infections are due to Acinetobacter baumannii, and it can cause various types of infections, mostly related to intensive care and invasive treatments (ventilatorassociated pneumonia (47% cases), bloodstream infections, surgical site infections, urinary tract infections (45% cases), skin and soft tissue infections, meningitis). For decades the genus Acinetobacter has undergone several taxonomical modifications. In the last few years these organisms are genetically modifying into highly resistant forms resulting in untreatable nosocomial infections and health care associated infections. A. baumannii can cause severe or fatal illnesses, especially in critically ill patients with low immune responses, and can increase patient mortality along with hospital costs. Studies show that the mortality rate of hospitalised patients infected with A. baumannii is 8-23%, and 10-43% at intensive care units. Aim of the study. Determining the degree of spread of nosocomial infections caused by Acinetobacter spp., nosological structure, epidemiological features, antibiotic resistance. Materials and methods. A descriptive cross-sectional study was conducted for 2014–2016 on the model of the Republican Clinical Hospital, the Institute of Neurology and Neurosurgery, and the Institute of Emergency Medicine. Results. In 2014-2016, in the three hospitals mentioned above, 1,005 cases of purulent-septic infections caused by Acinetobacter spp. were investigated. Most often they are found in intensive care units, anesthesiology and intensive care (56.32%), surgery (15.72%) and traumatology and orthopedic (14, 82%). The largest share is occupied by A. baumannii (98.69%), compared with A. iwoffii (0.95%) and A. haemolyticus (0.36%). Acinetobacter strains are mainly found in monocultures (65.77%), but in 34.23% - in associations in which gram-negative microorganisms significantly prevail (79.86%), including P. aeruginosa (33.49%), K pneumoniae (17.33%) and E. coli (11.48%). In 81.13%, Acinetobacter strains are resistant to antibiotics, and only 18.87% are sensitive to them. Acinetobacter strains were more resistant to penicillins (97.02%), penicillins + beta-lactamase inhibitors (96.73%), cephalosporins I generation (99.40%), cephalosporins II generation (98.86%), cephalosporins III generations (97.44%), IV generation cephalosporins (93.88%), nitrofurans (98.97%), macrolides (94.38%). A higher sensitivity is manifested in the following groups of antibiotics: cyclic polypeptides (94.42%), tetracyclines (85.12%) and other antibacterial agents (50.96%). Conclusions. Most infections caused by Acinetobacter baumannii have been detected in patients hospitalized in intensive care units and surgical departments. Acinetobacter baumannii is resistant to most antibiotics, and sensitivity to the currently used antibiotics is significantly reduced. High prevalence of antibiotic-resistant strains of Acinetobacter spp. emphasizes the importance of the use of selective antibiotic therapy and the strict monitoring of measures to combat nosocomial infections.