Abstract
Introduction: Lactococcus garvieae is an uncommon cause of infective endocarditis (IE) and, despite the fact that synergy between beta‐lactam antibiotics and aminoglycosides has not been demonstrated for lactococci, combination therapy is often used. Case presentation: We report a case of suspected L. garvieae IE in an 82‐year‐old man, which was successfully treated with a combination of ampicillin and gentamicin. Despite careful dosing and monitoring of gentamicin levels, the patient developed a transient decrease in renal function and permanent bilateral vestibular deficiency. The combination of gentamicin and ampicillin did not demonstrate synergistic killing effects in vitro against the L. garvieae isolate from this patient. However, synergy was noted against two of the four L. garvieae isolates tested. Unfortunately, an Etest‐based method, which would be easy to use in a routine laboratory, was unable to predict synergy in the time‐kill methods. Conclusions: The use of combination therapy in IE is based solely on in vitro synergy between beta‐lactams and aminoglycosides. Here we demonstrate that a combination of ampicillin and gentamicin induces synergistic killing only of some L. garvieae isolates. Since synergy does not seem to be omnipresent, the risks for aminoglycoside toxicity must be carefully weighed against the potential theoretical benefit of combination therapy in L. garvieae IE.
Highlights
Lactococcus garvieae is an uncommon cause of infective endocarditis (IE) and, despite the fact that synergy between beta-lactam antibiotics and aminoglycosides has not been demonstrated for lactococci, combination therapy is often used.Case presentation: We report a case of suspected L. garvieae Infective endocarditis (IE) in an 82-year-old man, which was successfully treated with a combination of ampicillin and gentamicin
Infections caused by L. garvieae have been proposed to be mainly transmitted to humans from contaminated fish (Wang et al, 2007), and IE seems to be a common presentation of infection with the bacterium (Chan et al, 2011)
We describe a case of suspected IE with a L. garviaeae isolate, against which there was no synergism between the beta-lactam and gentamicin, where the patient had severe side-effects related to gentamicin treatment
Summary
Lactococcus garvieae is a Gram-positive, catalase-negative bacterium, growing in pairs or in short chains. The isolate from the patient described, as well as three other L. garvieae blood isolates from a patient with diverticulitis, a patient with IE (Rasmussen et al, 2014), and an infant with no obvious focus of infection were tested for possible synergistic effects between ampicillin (Sigma) and gentamicin (Schering-Plough). We used both time-kill experiments and Etest-based methods to detect possible synergy. A FIC below 0.5 indicates synergy and there was no synergy between ampicillin and gentamicin in the inhibition of growth of the L. garvieae isolates
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