Achieving bactericidal therapy and high-level aminoglycoside resistance

Infective endocarditis: report of a prospective study in an Indian hospital

Forty-six patients who fulfilled the Duke's clinical diagnostic criteria for infective endocarditis (IE) were evaluated. Thirty-five (76%) patients were below 40 years of age with rheumatic heart disease being the most common underlying heart lesion affecting 26 (56%). An obvious predisposing cardiac lesion could not be ascertained in 22%. Blood culture positivity was 44% with streptococcus heading the list. The incidence of the staphylococcal (25%) and gram negative bacillary endocarditis (15%) were found to be increasing. Streptococci were susceptible to penicillin with minimum bactericidal concentration: minimum inhibitory concentration within acceptable limits. However, the appearance of methicillin resistant staphylococcus aureus and high level gentamicin resistant enterococcus as aetiological agents of infective endocarditis were found to add to the complexity of the problem. With the emergence of drug-resistant organisms as causative agents of IE, whenever medical therapy is the primary method of treatment of this condition, the selection of antibiotics should depend upon extensive in vitro testing and in vivo monitoring of clinical efficacy.

Endocarditis due to high level gentamicin resistant Enterococcus faecium

We describe the first reported case in the literature of bacterial endocarditis caused by Enterococcus faecium that was highly resistant to gentamicin. The case is unusual in that it followed a successfully treated Streptococcus sanguis endocarditis. The micro-organism was susceptible only to the glycopeptide antibiotics, vancomycin and teicoplanin and to agents such as pristinamycin and daptomycin which are not routinely available for treatment. It illustrates the therapeutic dilemma posed by serious infections with such micro-organisms and supports previous observations that early heart valve replacement surgery may be necessary to achieve cure of endocarditis due to enterococci which are highly resistant to gentamicin. It further emphasises the importance of screening for high-level aminoglycoside resistance in enterococci in all life threatening enterococcal infections, including endocarditis, septicaemia and meningitis when aminoglycoside-penicillin synergy is required for successful treatment.