Lactobacillus spp

• Gram positive bacilli morphology varies from short and plump to long and slender bacilli (anaerobic)

These organisms are part of the normal flora of the oropharynx and gastrointestinal/female genitourinary tracts. 

They have been associated with infections mostly in immunocompromised patients (rarely in immunocompetent individuals).  They can cause bacteremia, endocarditis (high mortality/morbidity), pleuropulmonary infections, intra-abdominal abscesses, chorioamnionitis, meningitis, cholecystitis, pyelonephritis, prosthetic joint infections, and dental abscesses.

Vancomycin resistant lactobacilli infections have been associated with CAPD peritonitis following prolonged vancomycin therapy.

Septicemia with this organism is rare and tends to occur in immunocompromised and/or severely debilitated individuals, sometimes following ingestion of probiotic agents containing lactobacilli. 

Lactobacillus spp have rarely been implicated in upper urinary tract infection in patients with anatomical abnormalities/stasis.

Usual Susceptibility Pattern

These organisms are usually susceptible to penicillin, linezolid, daptomycin, and macrolides.

They have variable susceptibility to clindamycin and tetracycline.  Of the tetracyclines, minocycline appears to be the most active.

They are usually resistant to metronidazole, aminoglycosides, and cephalosporins. 

Vancomycin resistance is common in clinical isolates but variable in Lactobacillus spp. from vaginal sources.

Daptomycin, linezolid, tetracycline, and macrolide resistance has been reported.

Quinolones have unreliable activity.

L. acidophilus is susceptible to penicillin and vancomycin.

L. rhamnosus, L. casei are resistant to metronidazole and vancomycin.