Virulence factors genes and drug resistance in Pseudomonas aeruginosa strains derived from different forms of community and healthcare associated infections

Background: The pathogenesis of Pseudomonas aeruginosa (PA) infection is multifactorial and depends mainly on two types of virulence determinants: virulence factors involved in acute infections and membrane bound factors, and virulence factors involved in chronic infections. The aim of this laboratory-based study was to analyse the resistance and virulence of PA strains isolated from different types of infections in hospitalised and non-hospitalised patients in Southern Poland. Material/Methods: Non-repetitive samples from urinary tract infections (UTI), bloodstream infections (BSI) and pneumonia (PNU) were collected. Isolates were screened for the presence of virulence factors by PCR method. Antimicrobial susceptibility testing was performed using disc diffusion method. Metallo-beta-lactamases (MBLs) were detected using an imipenem-EDTA double-disc synergy test. Results: There were 232 specimens collected: UTI-152, PNU-69, BSI-11. Fifty-one (22%) strains were classified as multidrug resistant (MDR), 23 (10%) as extensively-drug resistant (XDR). MDR/XDR strains were more frequently isolated from pneumonia (OR = 2.28). The prevalence values for the genes of effector proteins were 82.8% for exoS, 89% for exoY, and 24% for exoU. The simultaneous detection of four effector proteins was confirmed in 10.4% of the strains. pilB was more prevalent in isolates from the elderly (p=0.013). lasB occurred more frequently in PNU (p=0.048). Three of the genes were more prevalent in isolates from patients hospitalised in ICU (lasB (p=0.017), aprA (p=0.022), phzS (p=0.039)). Conclusions: Understanding the contribution of selected virulence genes to the outcome of an infection may be important for the therapeutic management of patients infected with PA. Simultaneous detection of virulence factors and antimicrobial resistance might be particularly useful because both are clinically important during an infection

Antibiotic consumption versus the prevalence of multidrug-resistant Acinetobacter baumannii and Clostridium difficile infections at an ICU from 2014–2015

Background: Acinetobacter baumannii strains are currently the most commonly isolated non-fermenting rods at Polish intensive care units (ICUs), and they are the dominant aetiological agents of pneumonia. This study aimed to evaluate the prevalence of A. baumannii isolated from patients who were hospitalised at Sosnowiec Hospital’s ICU. We also investigated the drug sensitivity of A. baumannii in relation to antibiotic consumption expressed as the defined daily dose (DDD) and Clostridium difficile infection (CDI). Methods: We performed a retrospective, laboratory-based study, which comprised consecutive, non-repetitive A. baumannii isolates from bloodstream infections and patients with pneumonia who were hospitalised from 2014–2015. Results: In the analysed period, 187 A. baumannii strains constituted 13.5% of all pathogens from clinical samples. A total of 76.5% of these strains were extensively drug resistant. Resistance of A. baumannii to fluoroquinolones, amikacin, and trimethoprim/sulfamethoxazole exceeded 90%. A total of 95% of strains were resistant to imipenem and meropenem, and 100% were resistant to cephalosporins and tetracyclines. Antibiotic consumption was 191.54 DDD for 100 patient-days, and the highest use of antibiotics involved ampicillin with sulbactam. The cumulative CDI incidence rate was 2.4%. Conclusions: In our ICU, all of the strains were extensively drug resistant and sensitive to colistin. The significantly high consumption of carbapenems, fluoroquinolones, and aminoglycosides should be reduced because the high CDI incidence is probably related to extensive antibiotic consumption. Keywords: Acinetobacter baumannii, Hospital infections, Multidrug resistance, Carbapenems, Antibiotic consumption, Clostridium difficil

Virulence and antimicrobial resistance of Staphylococcus aureus isolated from bloodstream infections and pneumonia in Southern Poland

Objectives: Staphylococcus aureus remains the most important cause of infections in hospitals and long-term care facilities. The aim of this study was to analyse the resistance, virulence, and epidemiological and genetic relationships of S. aureus from bloodstream infections (BSIs) and pneumonia from patients in Southern Poland. Methods: All strains were tested for antimicrobial susceptibility using the disk diffusion method. Etest was also performed for vancomycin, teicoplanin, tigecycline, oxacillin, cefoxitin and penicillin. PCR amplification was used to detect selected virulence genes. The genetic similarity of methicillin-resistant S. aureus (MRSA) isolates was determined by spa typing and pulsed-field gel electrophoresis (PFGE). Using the BURP algorithm and the Ridom SpaServer database, spa types were clustered into different clonal complexes (spa-CCs). Results and conclusions: MRSA strains were observed at a prevalence of 26.7%, but 88.6% of hospital-acquired infections were MRSA, with no difference between BSIs and pneumonia. The highest resistance was observed to erythromycin and tobramycin. None of the strains were resistant to linezolid, glycopeptides or tigecycline. The strains had no significant virulence factors and the number of virulence genes present did not correlate with the degree of drug resistance. PFGE typing showed relatively high diversity of strains. The majority of isolates belonged to spa type t003 (CC5)