aerobic gram-positive bacilli part ii genital culture unit division of medical technology carol...
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Aerobic Gram-Positive BacilliPart II
Genital Culture Unit
Division of Medical Technology
Carol Larson MSEd, MT(ASCP)
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• Gram stain– Morphology– Arrangement
• Formation of spores
• Catalase reaction
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Differentiation ofMajor GPR Genera
• Spore-forming GPR, catalase positive– Bacillus species– Bacillus anthracis– Bacillus cereus
• Nonspore-forming GPR, catalase positive– Listeria monocytogenes– Corynebacterium species (diphtheroids)– Corynebacterium diphtheriae– Corynebacterium jekeium
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GPR Discussed in Student Lab
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
• Branching Nocardioform GPR– Nocardia species– Streptomyces species
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GPR Discussed in This Lecture
• Pleomorphic gram-variable bacilli
• Non-sporulating
• Specimen gram stain:– Clue cells
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Gardnerella vaginalis
Gram Stain
GPR, pleomorphic, Non-spore forming, Catalase negative
• Does not grow on sheep blood agar
• Human Blood Agar (V-agar, HBT-agar)– Small colonies with diffuse zone of
beta-hemolysis
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Gardnerella vaginalis
Colony Morphology
GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative
• Oxidase negative
• Sodium hippurate usually positive
• SPS sensitive
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Gardnerella vaginalis
Identification
GPR, pleomorphic, Non-spore forming, Catalase negative
• Normal vaginal flora
• Bacterial vaginosis– Polymicrobic infection with Mobiluncus and
Bacteroides– Diagnosis
• Homogeneous, gray discharge• Clue cells• Amine or fishy odor when add 10% KOH• Culture not necessary for diagnosis
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Gardnerella vaginalis
Clinical Significance
GPR, pleomorphic, Non-spore forming, Catalase negative
What are the key identification characteristics to determine if Gardnerella vaginalis is the cause of bacterial vaginosis?
Examine vaginal specimen for presence of a homogeneous, gray discharge, clue cells on the Gram stain, and an amine or fishy odor when adding 10% KOH. A culture is not recommended, but if done, G. vaginalis grows on V-agar/HBT-agar and it beta hemolytic.
• Two types– Long slender GPR in chains– Short GPCB
• Non-sporulating
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Lactobacillus species
Gram Stain
GPR, pleomorphic, Non-spore forming, Catalase negative
• Grows on BAP– Multiple colony morphologies– Nonhemolytic or alpha hemolytic
• Microaerophilic
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Lactobacillus species
Colony Morphology
GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative
• Sucrose “F”
• Vancomycin “R”
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Lactobacillus species
Identification
GPR, pleomorphic, Non-spore forming, Catalase negative
Lactobacillus species
Clinical Significance• Normal flora
– Mouth– GI tract– Female vaginal tract
• Rarely pathogenic– Endocarditis– Meningitis
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GPR, pleomorphic, Non-spore forming, Catalase negative
What is the clinical significance of Lactobacillus species?
It is considered normal flora of the mouth, gastrointestinal tract, and female genital tract
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
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Review
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
• Branching Nocardioform GPR– Nocardia species– Streptomyces species
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Aerobic GPR
Summary
Who am I?
HBT media shows beta-hemolysis
GramStain
Gardnerella vaginalis
Causes Bacterial Vaginitis