Molecular tracking of coagulase-negative staphylococcal isolates from catheter-related infections

Three molecular typing methods (pulsed-field electrophoresis, localization of the mecA gene, and probing the vicinity of mec) have been used for the characterization of 40 catheter-related isolates of coagulase-negative staphylococci (CNS) in 14 patients admitted to the same hospital. The 40 isolates yielded 14 different SmaI banding patterns and corresponding unique localizations of mecA, each associated with a unique ClaI mecA polymorph. In 6 of the 14 patients the contaminated skin at the catheter entry site was the source of 4 local infections and 2 cases of bacteremia. A contaminated hub was the origin of 2 local infections and 4 cases of bacteremia in 6 more patients. The remaining 2 patients had positive cultures from both skin and catheter hub. In each bacteremic patient, the CNS recovered from catheter-related sites (tip, skin, and/or hub) and the CNS recovered from blood were identical, but each of these matching isolates was unique to the particular patient, indicating a low rate of cross-infection from patient to patient. Although classical methods for typing CNS (e.g., biotype and antibiotype) are readily available for most hospital laboratories, they have limitations concerning reproducibility and discriminatory power. Molecular epidemiologic techniques can provide powerful support to traditional techniques in determining the etiologic role of CNS in the disease process

La millor comprensió del desenvolupament cardíac i el dany cel•lular en els miòcits ajudarà a definir dianes terapèutiques

En el cor embrional, la senyalització de mort cel•lular apoptòtica iniciada per receptors de mort i les caspases executores 3 i 7 exerceixen un paper important durant el desenvolupament cardíac no relacionat amb la mort cel•lular, i posteriorment són silenciats en l’adult, on les vies independents de caspases estan implicades en la mort cel•lular patològica. Resultats previs del nostre grup han contribuït a entendre com es regula i silencia en el cor l’expressió dels gens de la via apoptòtica depenent de caspases durant el desenvolupament; a més, resultats no publicats demostren que les caspases regulen el procés d’expressió de gens en el cor i, contràriament a la maquinària depenent de caspases, TatD, una nucleasa, ’expressa abundantment al cor postnatal. Es desconeixen les funcions de la senyalització apoptòtica durant el desenvolupament cardíac, tot i que són essencials per al desenvolupament, a més, la senyalització independent de caspases implicada al dany cel•lular en els miòcits només es coneix parcialment, el nostre objectiu és contribuir al coneixement d’ambdós fenòmens. Creiem que les caspases podrien processar proteïnes reguladores de l’expressió de gens musculars alterant la seva activitat, mentre que TatD té un paper rellevant en el dany cel•lular però també en la funció cardíaca normal. Volem caracteritzar la contribució de les caspases 3 i 7 en el desenvolupament cardíac, utilitzant models in vivo (estem finalitzant els creuaments necessaris per a disposar dels animals amb el genotip desitjat) i in vitro (pràcticament hem preparat tot el material i hem optimitzat els protocols per a tirar-ho endavant). També volem caracteritzar la funció de TatD durant el desenvolupament i fisiologia del cor i conèixer-ne la seva funció utilitzant models in vitro i in vivo.

Staphylococcus lugdunensis infective endocarditis. Description of 10 cases and analysis of native valve, prosthetic valve and pacemaker lead endocarditis clinical profiles

bolism. Surgery was needed in 51% of cases and mortality was 42%. Prosthetic valve endocarditis (nine of 60, 13%) predominated in the aortic position and was associated with abscess formation, required surgery, and high mortality (78%). Pacemaker lead IE (seven of 69, 10%) is associated with a better prognosis when antibiotic treatment is combined with surgery. Conclusions:S lugdunensis IE is an uncommon cause of IE, involving mainly native left sided valves, and it is characterised by an aggressive clinical course. Mortality in left sided native valve IE is high but the prognosis has improved in recent years. Surgery has improved survival in left sided IE and, therefore, early surgery should always be considered. Prosthetic valve S lugdunensis IE carries an ominous prognosis.

A mouse peritonitis model for the study of glycopeptide efficacy in GISA infections

In recent years, the emergence of Staphylococcus aureus strains with reduced susceptibility to glycopeptides has raised considerable concern. We studied the efficacy of vancomycin and teicoplanin, as well as cloxacillin and cefotaxime, against the infection caused by four S. aureus strains with different glycopeptide and β-lactam susceptibilities (strains A, B, C, and D; MICs for vancomycin of 1, 2, 4, and 8 µg/ml respectively), using a modified model of mouse peritonitis. This optimized model appeared to be straightforward and reproducible, and was able to detect low differences in bacterial killing between antibiotics and also between different S. aureus strains. Bactericidal activities in peritoneal fluid for vancomycin, teicoplanin, cloxacillin, and cefotaxime decreased from -2.98, -2.36, -3.22, and -3.57 log10 cfu/ml, respectively, in infection by strain A (MICs for vancomycin and cloxacillin of 1 and 0.38 µg/ml, respectively) to -1.22, -0.65, -1.04, and +0.24 in peritonitis due to strain D (MICs for vancomycin and cloxacillin of 8 and 1,024 µg/ml). Our data confirm the superiority of β-lactams against methicillin-susceptible S. aureus and show that bactericidal activity of glycopeptides decreases significantly with slight increases in MICs; this finding suggests a reduced efficacy of glycopeptides in the treatment of serious glycopeptide-intermediate S. aureus infections

A mouse peritonitis model for the study of glycopeptide efficacy in GISA infections

In recent years, the emergence of Staphylococcus aureus strains with reduced susceptibility to glycopeptides has raised considerable concern. We studied the efficacy of vancomycin and teicoplanin, as well as cloxacillin and cefotaxime, against the infection caused by four S. aureus strains with different glycopeptide and β-lactam susceptibilities (strains A, B, C, and D; MICs for vancomycin of 1, 2, 4, and 8 µg/ml respectively), using a modified model of mouse peritonitis. This optimized model appeared to be straightforward and reproducible, and was able to detect low differences in bacterial killing between antibiotics and also between different S. aureus strains. Bactericidal activities in peritoneal fluid for vancomycin, teicoplanin, cloxacillin, and cefotaxime decreased from -2.98, -2.36, -3.22, and -3.57 log10 cfu/ml, respectively, in infection by strain A (MICs for vancomycin and cloxacillin of 1 and 0.38 µg/ml, respectively) to -1.22, -0.65, -1.04, and +0.24 in peritonitis due to strain D (MICs for vancomycin and cloxacillin of 8 and 1,024 µg/ml). Our data confirm the superiority of β-lactams against methicillin-susceptible S. aureus and show that bactericidal activity of glycopeptides decreases significantly with slight increases in MICs; this finding suggests a reduced efficacy of glycopeptides in the treatment of serious glycopeptide-intermediate S. aureus infections