Panton-Valentine leukocidin and staphylococcal cassette chromosome mec characterization of community acquired methicillin-resistant Staphylococcus aureus.

OBJECTIVES: Staphylococcus aureus (SA) represents one of the most important microorganism that is part of the normal microflora of humans, but in certain conditions can cause very serious infections. Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a wide spectrum of nosocomial and community associated infections worldwide. The aim of this study was to determine community acquired MRSA (CA-MRSA), as well as the frequency of Panton-Valentine leukocidin (PVL) genes and staphylococcal cassette chromosome mec (SCCmec) types in isolates obtained from outpatients in the region of 700,000 people (Canton Sarajevo, Bosnia and Herzegovina) Methods: Our investigation included phenotypic and genotypic markers such as antimicrobial resistance, pulsed-field gel electrophoresis (PFGE), SCC typing, and PVL detection. RESULTS: Antimicrobial susceptibility: all MRSA isolates were resistant to the ß-lactam antibiotics tested, and all isolates were susceptible to trimethoprim sulphamethoxazole, rifampicin, fusidic acid, linezolid, and vancomycin. After the PFGE analysis, the isolates were grouped into five similarity groups: A-E. The largest number of isolates belonged to one of two groups: C - 60% and D - 27%. In both groups C and D, SCCmec type IV was predominant (60% and 88.8%, respectively). A total of 24% of the isolates had positive expression of PVL genes, while 76% showed a statistically significantly greater negative expression of PVL genes. CONCLUSIONS: Using combination techniques, we were able to investigate the origin and genetic background of the strains. PFGE analysis revealed two large, genetically related groups of strains consisting of 87 isolates. Our results suggest failure to apply the screening policy, and a lack of knowledge about multiresistant MRSA strains. This study showed the local epidemiological situation which should be the basis of antimicrobial empiric therapy for non-hospitalized patients.

Comparison of final disinfection protocols using antimicrobial photodynamic therapy and different irrigants after single-file reciprocating instrumentation against intracanal bacterial biofilm - An in vitro study.

BACKGROUND: The aim of the study was to compare the efficacy of antimicrobial photodynamic therapy (aPDT) with irrigation protocols that include sodium hypochlorite (NaOCl), ethylenediaminotetraacetic acid (EDTA) or QMiX (combined irrigant: EDTA, chlorhexidine, detergent) solution after single-file reciprocating root canal instrumentation. METHODS: The study sample included 68 extracted mandibular human single canal teeth. The canals were inoculated with bacterial suspension made of wild strain of Enterococcus faecalis. After 17 days of incubation, the samples were assigned to experimental groups according to the final disinfection protocol and a control group. The root canals in all groups were, firstly, instrumented with Wave One Gold reciprocating system. Then the canals were disinfected as follows: Group 1. 2.5% NaOCl and EDTA followed by the application of the aPDT; Group 2. 2.5% NaOCl, EDTA and 2.5% NaOCl; Group 3. 2.5% NaOCl and QMIX solution; Group 4. 2.5% NaOCl and EDTA. In the control group, the canals were irrigated with saline solution. Microbiological samples were collected at baseline, after single-file instrumentation and after the final disinfection protocols. The samples were plated onto Mitis Salivarius agar plates for incubation. The colony forming units (CFUs) were counted, and the final number was determined based on the dilution factor. RESULTS: Reciprocating single-file instrumentation reduced CFUs significantly in all groups (p<0.05). No significant difference between Group 1 and Group 2 was observed (p=0.178). Irrigation with the QMiX was more efficient than the aPDT (p=0.02). CONCLUSIONS: The aPDT used after irrigation with NaOCl and EDTA demonstrated similar antimicrobial efficacy as conventional irrigation with NaOCl.

Metal ions, Alzheimer's disease and chelation therapy.

In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases.

Distributed lags time series analysis versus linear correlation analysis (Pearson's r) in identifying the relationship between antipseudomonal antibiotic consumption and the susceptibility of Pseudomonas aeruginosa isolates in a single Intensive Care Unit of a tertiary hospital.

The relationship between antibiotic consumption and selection of resistant strains has been studied mainly by employing conventional statistical methods. A time delay in effect must be anticipated and this has rarely been taken into account in previous studies. Therefore, distributed lags time series analysis and simple linear correlation were compared in their ability to evaluate this relationship. Data on monthly antibiotic consumption for ciprofloxacin, piperacillin/tazobactam, carbapenems and cefepime as well as Pseudomonas aeruginosa susceptibility were retrospectively collected for the period April 2006 to July 2007. Using distributed lags analysis, a significant temporal relationship was identified between ciprofloxacin, meropenem and cefepime consumption and the resistance rates of P. aeruginosa isolates to these antibiotics. This effect was lagged for ciprofloxacin and cefepime [1 month (R=0.827, P=0.039) and 2 months (R=0.962, P=0.001), respectively] and was simultaneous for meropenem (lag 0, R=0.876, P=0.002). Furthermore, a significant concomitant effect of meropenem consumption on the appearance of multidrug-resistant P. aeruginosa strains (resistant to three or more representatives of classes of antibiotics) was identified (lag 0, R=0.992, P<0.001). This effect was not delayed and it was therefore identified both by distributed lags analysis and the Pearson's correlation coefficient. Correlation coefficient analysis was not able to identify relationships between antibiotic consumption and bacterial resistance when the effect was delayed. These results indicate that the use of diverse statistical methods can yield significantly different results, thus leading to the introduction of possibly inappropriate infection control measures.