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).

Longevity and gender as the risk factors of methicillin-resistant Staphylococcus aureus infections in southern Poland.

BACKGROUND: The proportion of older people among the general population has risen. Staphylococcus aureus (SA) constitutes a significant problem. Underlying disease and functional debility, predispose the older adult to staphylococcal carriage and infection, specially bloodstream infection and pneumonia. METHODS: This is a retrospective cohort study of older patients with SA infections. We analyzed a database containing the results of laboratory cultures from patients treated in 2013 for SA infections and selected 613 hospitalized and non-hospitalized people aged ≥60 years. RESULTS: The prevalence of Methicillin-resistant SA (MRSA) were significantly different in categories of patients: from 14.1% in young old, 19.5% in old old and 26.7 in longevity. MRSA was significantly more frequently reported in cases of pneumonia, 40.4% of SA strains (p < 0.0001, OR 0.3, 95%CI 0.14-0.49). The nosocomial MRSA infections were more common in ICU departments: prevalence 36.8%, than in non-ICU departments: prevalence 17.3% (OR 2.8, 95%CI 1.06-7.34, p = 0.014). Bloodstream infections, which accounted for 6% of all infections, were more frequent in males (p = 0.0231, OR 2.25, 95%CI 1.098-4.604). The greatest increase in antibiotic resistance was related to trimethoprim/sulfamethoxazole (TMP/SXT), which increased to over 80% in the older study groups. All age groups demonstrated increased MIC90 values for glycopeptide and tigecycline. Although strains isolated from patients in all age groups remained sensitive to vancomycin, strains isolated from patients in the old-old and longevity groups demonstrated resistance to teicoplanin. The MIC90 for tigecycline was the highest in the group aged >90 years. CONCLUSIONS: MRSA constitutes a significant epidemiological problem in cases of hospital-treated pneumonia. The findings were similar for long-term-care facilities, where MRSA appears to affect male residents in particular, although there were fewer male residents than female residents. The low sensitivity to TMP/SXT of SA strains isolated from the oldest patients indicates potentially serious challenges pertaining to efficacious treatment of SA infections.

Age and other risk factors of pneumonia among residents of Polish long-term care facilities.

BACKGROUND: Pneumonia is one of the leading causes of morbidity and mortality in the elderly population. Nursing home-acquired pneumonia (NHAP) is probably the largest health problem in long-term care facilities (LTCFs). It is the second most common infection in LTCFs and frequently requires hospitalization. The aim of this study was to investigate the incidence rate of NHAP among LTCF residents, its microbial etiology, and the frequency of multidrug-resistant microorganisms. Risk factors for NHAP were analyzed. METHODS: This was a prospective study conducted on a group of 217 elderly subjects aged ≥65 years, recruited from the inhabitants of LTCFs, with disabled elderly individuals living in the community serving as controls. Continuous surveillance was carried out from December 1, 2009 to November 30, 2010. RESULTS: The incidence rate of NHAP in the observed population of Polish residents was 0.6/1000 resident-days. Vulnerability to NHAP was due to the poor general condition of residents, expressed by low Barthel index values (relative risk (RR) 1.6), the activities of daily living (ADL) score (RR 1.7), the Katz scale (RR 1.2), and limited physical activity (RR 1.6). Also significant were malnutrition (RR 2.3), the use of a bladder catheter (RR 1.3), dysphagia (RR 1.7), tracheotomy tube (RR 3.1), and gastric feeding tube (RR 3.5). Enterobacteriaceae were the predominant etiological agents of NHAP (56.3%). CONCLUSIONS: The significance of risk factors for NHAP among residents in LTCFs was confirmed. Unfortunately, we also found that a lack of proper supervision with regard to the microbiology of infections is characteristic of Polish health care and LTCFs. There is an opportunity to improve the medical care of patients with severe disabilities, limit the rise in antimicrobial resistance and the need for hospitalization, and improve the prognosis.

[Occurrence of surface protein genes from alpha-like protein (Alp) family in Streptococcus agalactiae isolates]. / Wystepowanie genów kodujacych bialka z rodziny Alp u Streptococcus agalactiae.

Distribution of serotypes and alpha-like surface protein (Alp) of Streptococcus agalactiae (Group B Streptococci - GBS) vary with geographical region, ethnic origin and the virulence of clinical isolates. Demonstration of different genotypes based on surface protein genes improves the potential of GBS subtyping, is essential in research on new vaccines against invasive neonatal infections and may be useful in epidemiological studies. The molecular characterization of protein gene profile of GBS isolates was the main aim of this study. We evaluated the applicability of multiplex PCR for the identification of GBS protein genes from Alp family, such as: epsilon, bca, rib, alp2, alp3, alp4 and evaluated presence of these genes in the group of GBS isolates originating from vaginal or rectal carriage in pregnant women. For statistical analysis the G2 (Likelihood ratio) test was used. P values of < 0.05 were considered significant. The surface protein genes were found in all investigated strains. The epsilon gene dominated (27%) in GBS isolates originating from healthy pregnant women. The other genes were detected with the following frequency: rib (21%), alp2 (21%), bca (17%) and alp3 (14%). In the analyzed population, GBS strains with alp4 gene were not found. A statistically significant relationship between surface protein genes and capsular polysaccharides was demonstrated (p < 0.0001). The results of our study show immense diagnostic usefulness of multiplex PCR for identification of genes encoding GBS surface proteins from Alp family.