Lactobacillus
Lactobacillus is a genus of Gram-positive, non-spore-forming, rod-shaped, aerotolerant bacteria that are part of the normal human microbiota, particularly in the gastrointestinal, genitourinary, and vaginal tracts. These organisms primarily produce lactic acid from sugars, contributing to an acidic environment that inhibits the growth of pathogens. Several species, such as L. plantarum and L. bulgaricus, are widely used in the food industry for the production of yogurt, cheese, and fermented products.
Although typically considered beneficial, Lactobacillus can behave as an opportunistic pathogen in immunocompromised patients or those with underlying conditions. Documented infections include:
- Infective endocarditis: often associated with L. acidophilus, especially in patients with structural heart disease or prosthetic valves.
- Bacteremia: linked to invasive procedures, parenteral nutrition, or prolonged use of broad-spectrum antibiotics.
- Urinary tract infections: although normally protective, Lactobacillus can contribute to infection in certain scenarios such as in postmenopausal women.
- Cytolytic vaginosis: characterized by overgrowth of Lactobacillus species, vaginal pruritus, abnormal discharge, and local discomfort.
Diagnosis:
Diagnosis relies on the isolation of Lactobacillus from sterile cultures (e.g., blood, urine, or tissue) in the presence of compatible clinical symptoms. In suspected endocarditis, repeated blood cultures and echocardiography are often required. Species-level identification and antimicrobial susceptibility testing are critical to guide therapy.
Treatment:
Treatment depends on the site and severity of infection, as well as the Lactobacillus species involved. Recommendations include:
- Targeted antibiotic therapy (penicillin, ampicillin, or vancomycin often combined with aminoglycosides in severe infections).
- Surgical intervention when complications like abscesses or valvular damage occur.
- Discontinuation of probiotic use, if applicable.
- Preventive measures in high-risk patients, especially those under immunosuppressive therapy or with indwelling medical devices.