Ralstonia pickettii bacteremia in a cardiac surgery patient in Belgrade, Serbia.

Ralstonia pickettii is an opportunistic bacterium found in the water environment with an increasing incidence as a nosocomial pathogen. The objectives of this study were to describe R. pickettii bacteremia in a cardiac surgery patient and to evaluate its ability to grow in a saline solution and to form biofilm. The patient in this study underwent mitral and aortic valve replacement surgery with two aortocoronary bypasses. She developed signs of respiratory and renal failure, therefore hemodialysis was started. After 25 days in an intensive care unit, the patient had recurrent episodes of fever with signs of bacteremia. R. pickettii was identified from blood cultures by MALDI-TOF MS. Antimicrobial susceptibility testing was performed using disc diffusion and broth microdilution methods in accordance with EUCAST methodology and results were interpreted following clinical breakpoints for Pseudomonas spp. The isolate was susceptible to all tested antimicrobial agents except aminoglycosides and colistin. Survival of R. pickettii was analyzed in saline solution with four different starting concentrations at 25 °C and 37 °C for six days. Biofilm capacity was tested using the microtiter plate method. R. pickettii showed substantial growth in saline solution, with starting concentration of 2 CFU ml-1 reaching 107 CFU ml-1 after six days. There was no significant difference between growth at 25 °C and 37 °C. This indicates that storage of contaminated solutions at room temperature can enhance the count of R. pickettii. Our strain did not show the capacity to form biofilm. The patient responded well to adequate treatment with ceftazidime, and after 48 days in ICU she was discharged to convalesce.

Inhibitory Effect of Newly-Synthesized Chalcones on Hemolytic Activity of Methicillin-Resistant Staphylococcus aureus.

Pathogenicity of methicillin-resistant Staphylococcus aureus (MRSA) is associated with a broad spectrum of virulence factors, amongst which is α-hemolysin. The aim of this study was to investigate the effect of three newly-synthesized chalcones (1,3- Bis-(2-hydroxy-phenyl)-propenone, 3-(3-Hydroxy-phenyl)-1-(2-hydroxy-phenyl)-propenone and 3-(4-Hydroxy-phenyl)-1-(2-hydroxy-phenyl)-propenone) on a-hemolysin production of clinical isolates of MRSA. Subinhibitory concentrations of the tested compounds reduced hemolytic activity of MRSA strains, with almost complete abolishment of hemolysis at concentrations in the range of 1/2-1/4 x MIC (25-12.5 µg/ml). In conclusion, newly-synthesized chalcones tested in this study showed potent inhibitory activity on α-hemolysin production of multiresistant and genetically diverse MRSA strains.

A case report of Listeria monocytogenes meningoencephalitis in General Hospital "Dr Radivoj Simonovir" Sombor.

INTRODUCTION: Listeria monocytogenes is one of the most common causes of bacterial central nervous system infections in adults. It often affects immunicompromised and elderly patients. Even with appropriate antimicrobial treatment, mortality due to Listeria monocytogenes meningoencephalitis is among the highest of all causes of bacterial central nervous system infections. CASE REPORT: We presented a previously healthy, 79-year-old farmer with typical clinical features of meningoencephalitis. The initial treatment with vancomycin and meropenem did not produce any clinical effect. On day six, Listeria monocytogenes was isolated from the cerebrospinal fluid and blood culture and identified by using conventional and automated microbiology methods. Antimicrobial susceptibility testing was performed by E test method. After bacterial isolation and identification, the administration of ampicillin and gentamicin was followed by the complete recovery of our patient. CONCLUSION: This case is presented to emphasize the negative outcome of empirical treatment when Listeria monocytogenes is not taken into consideration. Furthermore, the administration of ampicillin and gentamicin combination for treatment should be considered as the best therapeutic option in Listeria monocytogenes meningoencephalitis.