Duration of Carriage of Multidrug-Resistant Acinetobacter baumannii and its Impact on Infection Control Measures and Antimicrobial Use. Summary of the Doctoral Thesis
Authors:   ,   Rīga Stradiņš University, Liepiņš Māris 
Published: November 2024

Acinetobacter baumannii is a Gram-negative bacterium that can cause a variety of infections in humans, especially those with co-morbidities or reduced immune responses, such as patients in hospitals or military facilities. This micro-organism is particularly dangerous because it can be resistant to many antimicrobial agents, making treatment difficult. Over time, it has become a growing problem in healthcare facilities around the world, particularly in intensive care units where patients are particularly susceptible to such infections. There is therefore a need for increased attention and measures to control and prevent the spread of Acinetobacter baumannii infections. The number of countries reporting inter-regional spread of resistant A. baumannii has increased. Between 2017 and 2021, the average percentage of countries in the European Union/European Economic Area with combined resistance to carbapenems, fluoroquinolones and aminoglycosides increased significantly from 32.1 % to 36.8 % (ECDC, WHO. 2023). The latest available data on Acinetobacter resistance in Latvia also show an increasing trend (ECDC, 2024). In 2022, Latvia still has one of the highest resistance rates of A. baumannii: 63.3 % of Acinetobacter spp. isolates have combined resistance to fluoroquinolones, aminoglycosides, carbapenems. At Riga East University Hospital, the largest inpatient care facility in Latvia, there has been a clear trend of increasing infection with resistant A. baumannii in the hospital in recent years. Resistant A. baumannii is now a strict healthcare-associated pathogen and is particularly dangerous because treatment of infections caused by it is severely limited. Patients with resistant A. baumannii are predominantly infected in intensive care units. The most common sites of colonization are the pharynx, airways, wounds and invasive devices, while the most common infections caused by resistant A. baumannii are pneumonia, central venous catheter-associated sepsis, surgical wound infections and central nervous system infections. Patients colonized with resistant micro-organisms at hospital re-admission are a potential source of infection with these resistant micro-organisms, the subject of subsequent increased infection control, and pose a challenge to clinicians in their daily practice when empirical antimicrobial treatment of severe infections or antimicrobial prophylaxis is required. Carriage of other multidrug-resistant microorganisms, such as Enterobacteriaceaesecreting extended-spectrum beta-lactamases (ESBLs), is known to reach 43 % at 12 months post-infection (Titelman et al., 2014). In a small study (Marchaim et al., 2007) of 30 patients with a history of multidrug-resistant A. baumannii (MRAB) infection, 17 % only re-isolated MRAB, with a median of 17.5 months post-infection. All patients with clinically and epidemiologically relevant resistant micro-organisms are registered in the Riga East University Hospital internal information system. At this point in time, there is no time limit for the accumulation of data, as long-term carriage of resistant micro-organisms has been demonstrated by reference to studies. The purpose of the data accumulation is, if necessary, the timely application of infection control measures and rational antimicrobial treatment or prophylaxis in case of current or re-admission. In routine practice, it has been observed that in re-hospitalized patients with a history of resistant A. baumannii, this micro-organism is re-detected if the patient has a chronic disease, a long-standing wound or an invasive device. At this point in time, there is no specific information on whether patients with a history of resistant A. baumannii require infection control measures for re- and/or routine hospitalization and whether empirical antimicrobial therapy or prophylaxis against resistant A. baumannii should be used if necessary. The Doctoral Thesis was developed at Riga East University hospital, Latvia. Defence: at the public session of the Promotion Council of Health Sciences on 12 November 2024 at 15.00 in the Hippocrates Lecture Theatre, 16 Dzirciema Street, Rīgas Stradiņš University and remotely via online platform Zoom. 3.3 Medical and Health Sciences; Sub-Sector – Health Sciences. Keywords: Acinetobacter baumannii; healthcare associated infections; antimicrobial resistance; carriage of microorganisms; infection control.