Aerobic Gram-Positive BacilliPart II

Genital Culture Unit

Division of Medical Technology

Carol Larson MSEd, MT(ASCP)

Please click audio iconto hear Carol’s narration

• Gram stain– Morphology– Arrangement

• Formation of spores

• Catalase reaction

Click icon for audio

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

Click icon for audio

GPR Discussed in Student Lab

• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species

• Branching Nocardioform GPR– Nocardia species– Streptomyces species

Click icon for audio

GPR Discussed in This Lecture

• Pleomorphic gram-variable bacilli

• Non-sporulating

• Specimen gram stain:– Clue cells

Click icon for audio

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

Click icon for audio

Gardnerella vaginalis

Colony Morphology

GPR, pleomorphic, Non-spore forming, Catalase negative

• Catalase negative

• Oxidase negative

• Sodium hippurate usually positive

• SPS sensitive

Click icon for audio

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

Click icon for audio

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

Click icon for audio

Lactobacillus species

Gram Stain

GPR, pleomorphic, Non-spore forming, Catalase negative

• Grows on BAP– Multiple colony morphologies– Nonhemolytic or alpha hemolytic

• Microaerophilic

Click icon for audio

Lactobacillus species

Colony Morphology

GPR, pleomorphic, Non-spore forming, Catalase negative

• Catalase negative

• Sucrose “F”

• Vancomycin “R”

Click icon for audio

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

Click icon for audio

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

Click icon for audio

Review

• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species

• Branching Nocardioform GPR– Nocardia species– Streptomyces species

Click icon for audio

Aerobic GPR

Summary

Who am I?

HBT media shows beta-hemolysis

GramStain

Gardnerella vaginalis

Causes Bacterial Vaginitis