Gram-Positive Bacilli Part Two MLAB 2434: Microbiology Keri Brophy-Martinez

Rods Erysipelothrix Lactobacillus Gardnerella vaginalis

Erysipelothrix rhusiopathiae: General characteristics Gram positive, non–spore-forming, pleomorphic rods (can produce long filaments) Distributed in nature Can cause disease in animals (swine, turkey, sheep); swine is the main reservoir Humans acquire the infection through occupational exposure, such as cuts & scratches (fish handlers, animal products)

Erysipelothrix rhusiopathiae: Clinical Infections Erysipeloid Self-limiting localized infection at the site of inoculation Produces painful swelling, usually on the hands or fingers Heals within 3 to 4 weeks Treat with penicillin, cephalosporin, erythromycin Endocarditis May occur in those who have had valve replacements Disseminated infections may occur, but rarely

Laboratory Diagnosis: Erysipelothrix rhusiopathiae Colony Morphology CO2 is required Grows on blood or chocolate agar Colonies may appear gray or translucent, pinpoint Alpha hemolysis or nonhemolytic

Laboratory Diagnosis: Erysipelothrix rhusiopathiae Microscopic Morphology Pleomorphic, Gram-positive thin rods that may form long filaments or short rods Arranged singly, in short chains, or in a V shape

Laboratory Diagnosis: Erysipelothrix rhusiopathiae Identification Catalase, nitrate, urease negative Nonmotile Production of H2S on TSI Test tube brush growth in semisolid motility media

Characteristics of Corynebacterium, Listeria, and Erysipelothrix

Lactobacillus resistant to vancomycin (helps in diagnosis) Widely distributed in nature Normal flora of mouth, GI tract and female genital tract Treat with pencillin plus an aminoglycoside resistant to vancomycin (helps in diagnosis) Clinical Infections Bacterial vaginosis Bacteremia, endocarditis, meningitis (rare)

Lactobacillus Colony Morphology Lab Diagnosis Microscopic Morphology Long, slender gram positive pleomorphic bacilli Non-spore forming Colony Morphology SBA Pinpoint α- hemolytic or gamma colonies Lab Diagnosis Catalase negative

Gardnerella vaginalis Member of the normal flora of the female genital tract Associated with bacterial vaginosis Foul odor Vaginal pH > 4.5

Laboratory Diagnosis: Gardnerella vaginalis Wet Prep Look for clue cells Large epithelials with various bacterial types on edges Gram stain Small, thin Gram variable rods

Laboratory Diagnosis: Gardnerella vaginalis Cultural Characteristics Growth on BAP, CA No growth on MAC Human blood bilayer tween “V” agar Beta-hemolytic Requires a CO2 environment Catalase negative

References Engelkirk, P. G., & Duben-Engelkirk, J. (2008). Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology . Baltimore, MD: Lippincott Williams & Willkins. http://en.wikipedia.org/wiki/Lactobacillus http://www.thefullwiki.org/Corynebacterium_diphtheriae http://quizlet.com/10262287/print/ Kiser, K. M., Payne, W. C., & Taff, T. (2011). Clinical Laboratory Microbiology: A Practical Approach . Upper Saddle River, NJ: Pearson Education, Inc. Mahon, C. R., Lehman, D. C., & Manuselis, G. (2011). Textbook of Diagnostic Microbiology (4th ed.). Maryland Heights, MO: Saunders.