Etiology and Antimicrobial Resistance of Secondary Bacterial Infections in Patients Hospitalized with COVID-19: A Retrospective Analysis

ABSTRACT

Background. One of the complications in patients hospitalized with COVID-19 is a secondary bacterial infection. Its frequency can reach 15%, which makes it important to determine the etiology and antimicrobial resistance of the key pathogens responsible for the development of this pathology, in order to further improve the practice of prescribing and increase the effectiveness of antimicrobial chemotherapy. Aims — to assess the etiological structure and antibiotic resistance of the main pathogens of SBIs to improve the practice of antibiotic prescription. Methods. This retrospective study reviewed medical records of the patients hospitalized with COVID-19 in the Moscow city hospital No. 4 between April 28 and November 1, 2020. Demographic, clinical outcomes, etiology, and antimicrobial resistance data of the SBIs were collected. Outcomes were also compared between patients who were classified as severe and critical on admission. Results. Among 3180 patients hospitalized with COVID-19, 220 (6.9%) patients had acquired SBIs, and 50.0% of cases were fatal. The mean age was 72.7 ± 13.07 years. A higher mortality rate was observed in the group of critical patients (63%). 560 strains of bacteria isolated from the SBIs (58.8% isolated from lungs, 21% from urine and 20.2% from blood). 330 strains (58.9%) were Gram-negative bacteria. 109 patients had infections with mixed bacteria. 45 of them (20.5% of the total number of patients included in the study) had 2 pathogens, and 64 patients (29.1%) 3 or more strains. The top three bacteria of SBIs were A. baumannii (23.6%;132/560), K. pneumoniae (22.9%;128/560), and S. epidermidis (10.4%;58/560). The isolation rates of carbapenem-resistant A. baumannii were 97%. Cefoperazone/sulbactam was the most active antibiotic against this pathogen with 62.1% sensitivity. Among K. pneumoniae strains, the level of resistance to carbapenems was 77.4% to meropenem and 54% to imipenem. The proportion of resistant strains to tigecycline and to colistin was 4 and 2.3% respectively. Meticillin resistance was present in 38.5% of S. aureus. 50% of E. faecium strains were vancomycinresistant. Conclusions. Gram-negative bacteria, especially A. baumannii and K. pneumoniae, were the main pathogens, and the resistance rates of the major isolated bacteria were generally high, which indicates that more accurate use of antibacterial agents is necessary for SBIs in patients hospitalized with COVID-19.