Microbiology and treatment of infective endocarditis

Abstract

Introduction: The infective endocarditis is a disease that has been changing its microbiological profile during the past year as a consequence of the raise in the cases of infection associated to health care, seniors and a greater number of intracardiac devices. In spite of the advances in diagnosis and treatment it continues presenting a high mortality rate. Objectives: To compare the microbiologic characteristics and guidelines for antimicrobial treatment that were most used in two periods of time: 1996–2004 and 2005–2013. Material and methods: A retrospective study revising the clinical histories of patients that were diagnosed with IE from January 1996 until February 2013 in this hospital. The microbiologic results were obtained based upon the results of mass-produced blood cultures. The two periods will be compared using chi-squared tests for qualitative variables and ANOVA or Kruskal–Wallis for quantitative values. Results: 121 cases with diagnose of IE were included. The most frequent pathogen observed was Streptococcus, in 34% of the cases, followed by Staphylococcus aureus in 19%, the Enterococcus almost 9%, then Staphylococcus Coagulase Negative (SCN) and Bacillus Gram Negative (BGN) mean approximately a 4.5% of the total of the endocarditis. If we compare both periods we could appreciate that Streptococcus has raised in the last years (31.7% vs. 37.3%) the same with SCN (15.9% vs. 21.5%). The pathogens involved in the infection of the native valve and late prosthetic are put on top, being Streptococcus as the most frequent (37.5%), followed by S. aureus (18.8%), while in the early prosthetic valve is SCN (27.3%), followed by S. aureus and Enterococcus (18.2% each one). Comparing both periods it should be pointed out that the raise in infections is due to S. aureus over the early prosthetic valve in the second period of our study (0% vs. 33%). It was not detected by any penicillin resistance on the Streptococcus spp. All the S. aureus were sensible to oxacillin. The Enterococcus was sensible to penicillin and 48% showed a pattern of high resistance to aminoglycosides. The treatment guidelines most used were penicillin or ampicillin associated to gentamicin (25.2%), vancomycin associated to gentamicin (23.4%), penicillin, ampicillin or ceftriaxone (13.10%) and finally ceftriaxone plus gentamicin (12.1%). Comparing both periods, a significant drop in the use of ampicillin or penicillin associated to gentamicin, and an increase of the association of ceftriaxone plus gentamicin can be observed. Conclusions: A raise of the prevalence of the early prosthetic infection due to S. aureus in the second period of time was analyzed. In our experience the classic guidelines of combination are still valid as much for endocarditis streptococcal, enterococcal and staphylococcal.