Incidence and Prognostic Value of Known Genetic Aberrations in Patients with Acute Myeloid Leukemia--a Two Year Study.

BACKGROUND: In this work, we evaluated the incidence and prognostic value of several genetic aberrations in patients with a diagnosis of acute myeloid leukemia (AML). PATIENTS AND METHODS: We analysed 90 patients: 42 males (mean age 54.5 years) and 48 females (mean age 59 years), with AML. The genetics of all leukemia samples was studied using conventional cytogenetics, the interphase fluorescence in situ hybridisation as well as the standardized RTPCR protocol. RESULTS: In 34.4% of patients, we detected at least one of the analysed genetic aberrations, except the CBFB MYH11, which we did not detect. Translocation t(8;21)/ AML1 ETO was found in 4.4% of patients with a mean age of 45.4 years, while none of these patients was older than 55 years. Translocation t(15;17)/ PMLRARA was found in 5.5% of patients with a mean age of 52.6 years and an almost equal distribution between younger and older patients. The MLL gene rearrangements were found in 6.6% of patients, the -5/ 5q- and/ or -7/ 7q- aberrations in 7.7% of patients, while the most frequent genetic abnormality in our study was trisomy 8 (10%). Moreover, we found a favorable clinical outcome in patients expressing fusion genes AML1-ETO or PMLRARA in contrast to an adverse clinical outcome with few remissions and death in AML patients with MLL, -5q/ -5 and -7q/ 7-. Finally, an intermediate prognosis was found in patients with trisomy 8. CONCLUSION: In this study, we found a good congruence with published literature on the incidence and prognostic value of several well established AML-associated genetic aberrations. This simple genetic-based classification system helps us to identify patients with a favorable, intermediate or unfavorable prognosis and to treat them with the best currently available therapy. However, analysis of new genetically defined abnormalities in AML is necessary for development of better therapeutic strategies and/or diagnostics.

Changes in the incidence of periodontal pathogens during long-term monitoring and after application of antibacterial drugs.

The incidence of potential periodontal pathogens (Aggregatibacter actinomycetemcomitans, formerly Actinobacillus actinomycetemcomitans, Tannerella forsythia, Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia and Capnocytophaga ochracea) was monitored in patients with chronic periodontitis and in healthy control subjects. Two types of studies were carried out in which the composition of the bacterial communities in different niches of the same oral cavity ecosystem was investigated. Fluctuation or at least pronounced quantitative changes in the incidence of individual species in time were documented in the long-term study as well as after the local administration of antibacterial drug Chlo-Site or Metronidazole. Even within two weeks, a turnover of the monitored bacteria in separate niches of the oral biotope can be detected. A relatively high incidence of the tested periopathogens in the clinically healthy teeth of patients implies that even the "healthy" niches in the periodontal biotope function as a dynamic reservoir of periopathogenic microorganisms. This should be kept in mind when a local application of antibacterial compounds is used in the therapy of periodontal disease.

In vitro activity of telithromycin and quinupristin/dalfopristin against methicillin-resistant coagulase-negative staphylococci with defined resistance genotypes.

We determined the activities of new antibiotics telithromycin (ketolide) and quinupristin/dalfopristin (streptogramins) against 88 macrolide and/or lincosamide resistant coagulase-negative staphylococci (CoNS) isolates with defined resistance gene status. Telithromycin susceptibility was determined only in erythromycin-sensitive isolates (15) indicating the same mechanisms of resistance. In contrast, all erythromycin-resistant isolates (73) were either constitutively resistant to telithromycin (13 isolates with constitutive erm genes) or demonstrated telithromycin D-shaped zone (60 isolates with inducible msr(A) and/or erm). However, the level of inducible resistance conferred by msr(A) (35 isolates) was borderline even after induction by erythromycin. No quinupristin/dalfopristin resistant isolate was observed if tested by disk-diffusion method (DDM) but 18 isolates were intermediate (MIC = 1-3 mg/L) and two isolates resistant (MIC = 8 mg/L) if tested by E-test. All these isolates were resistant to streptogramin A and harbored vga(A) gene (1 isolate) or vga(A)LC gene (19 isolates). MICs for quinupristin/dalfopristin were higher for isolates with combination of streptogramin A resistance and constitutive MLSB resistance (MIC = 3-8 mg/L in 4 isolates) than for streptogramin A-resistant isolates susceptible to streptogramin B (MIC = 0.5-2 mg/L in 16 isolates). In addition to S. haemolyticus, vga(A)LC was newly identified in S. epidermidis and S. warnerii indicating its widespread occurrence in CoNS. Misidentification of low-level resistant isolates by DDM may contribute to dissemination of streptogramin A resistance.

The prospects of advanced molecular methods in the detection of periodontal pathogens: hybridization in situ.

The paper summarizes the present state in the diagnostics of periodontal pathogens. Both the main advantages and drawbacks of the classic cultivation methods and those of the new DNA techniques are discussed. From the emerging methods of molecular diagnostics, the method of in situ hybridization is presented in more details. Its principle, various modifications of performance and possibilities of use are explained, including examples of its application in the detection of periodontal pathogens.

A new evolutionary variant of the streptogramin A resistance protein, Vga(A)LC, from Staphylococcus haemolyticus with shifted substrate specificity towards lincosamides.

We found a new variant of the streptogramin A resistance gene, vga(A)LC, in clinical isolates of Staphylococcus haemolyticus resistant to lincomycin and clindamycin but susceptible to erythromycin and in which no relevant lincosamide resistance gene was detected. The gene vga(A)LC, differing from the gene vga(A) at the protein level by seven amino acid substitutions, was present exclusively in S. haemolyticus strains resistant to both lincosamides and streptogramin A (LS(A) phenotype). Antibiotic resistance profiles of the ATP-binding cassette (ABC) proteins Vga(A)(LC) and Vga(A) in the antibiotic-susceptible host S. aureus RN4220 were compared. It was shown that Vga(A)LC conferred resistance to both lincosamides and streptogramin A, while Vga(A) conferred significant resistance to streptogramin A only. Detailed analysis of the seven amino acid substitutions, distinguishing the two related ABC proteins with different substrate specificities, identified the substrate-recognizing site: four clustered substitutions (L212S, G219V, A220T, and G226S) in the spacer between the two ATP-binding cassettes altered the substrate specificity and constituted the lincosamide-streptogramin A resistance phenotype. A transport experiment with radiolabeled lincomycin demonstrated that the mechanism of lincosamide resistance in S. haemolyticus was identical to that of the reported macrolide-streptogramin B resistance conferred by Msr(A).