Infective Endocarditis Due to Lactobacillus acidophilus Group Report of a Case and Review of the Literature

Abstract

Lactobacilli are usually considered non-pathogenic. However, only a few cases of severe infection due to lactobacilli have been reported. Among them infective endocarditis (IE) are extremely rare. We described here the first case of IE due to Lactobacilli in Japan.
A 26-year-old housewife was admitted to our hospital with a low grade fever, malaise and anorexia during the last three months after artificial abortion. She had been suffering from pulmonary stenosis and regargitation since the operation of Fallot's tetralogy at the age of 10 years old. On admission physical examinaiton revealed a low grade fever, moderate cardiomegaly, a grade 3/6 systolic and diastolic murmur and thrill over the entire anterior chest. Laboratory studies showed a WBC count of 4, 900/mm³ (N. band 26%, N. seg 36%); ESR was 67 mm/h.; and CRP was moderately positive. Four blood cultures taken over three days resulted in a pure culture of a Gram positive bacillus, which was identified as Lactobacillus acidophilus group. The same organism was also isolated from the uterine secretion. The organism seemed to be a new species, because their DNA/DNA homology did not coincide with those of any standard strains of Lactobacillus acidophilus. Disc sensitivity test revealed that the organism was sensitive to penicillin-G (PCG). The MIC of PCG against the isolate was 0.0125 μg/ml. She was treated with 12 million units of intravenous PCG per day for three weeks. And thereafter she was treated with erythromycine 1, 200 mg per day for two weeks because of mild granulocytopenia due to penicillin allergy. Neither vascular phenomena nor heart failure developed in her hospital course. She remained well for 18 months after the therapy.
Only 27 cases of IE due to Lactobacilli have previously been described in the world. The clinical features of these cases are summarized as follow: most of the patients have a subacute clinical course and have a history of oral disease and mitral or aortic valvular disease or congenital heart disease as underlying disorders. For the treatment of IE due to Lactobacilli, high doses of intravenous PCG for more than four weeks have proved successful. In conclusion, IE due to Lactobacilli is very similar to those of streptococcal origin.