Aerobic Gram-Positive BacilliPart II
Division of Medical TechnologyCarol 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 vaginalisColony Morphology
GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative• Oxidase negative• Sodium hippurate usually positive• SPS sensitive
Click icon for audio
Gardnerella vaginalisIdentification
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 vaginalisClinical 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– Short GPR– Long, filamentous
GPR• Non-sporulating
Click icon for audio
Erysipelothrix rhusiopathiae Gram Stain
GPR, pleomorphic, Non-spore forming, Catalase negative
Erysipelothrix rhusiopathiae Colony Morphology
• Grows on BAP– Nonhemolytic or
alpha hemolytic• Microaerophilic
Click icon for audio
GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative• Motility
– Nonmotile– Test-tube brush growth pattern in
semisolid motility tube at 48 hours
• H2S positive in KIA/TSI (only GPR)• Sucrose non“F”
Click icon for audio
Erysipelothrix rhusiopathiae Identification
GPR, pleomorphic, Non-spore forming, Catalase negative
• Zoonotic– Swine erysipelas (fatal to pigs)
• Man – skin disease– Erysipelas– Direct contact with infected animal– Rarely disseminates causing septicemia
with arthritis or endocarditis
Click icon for audio
Erysipelothrix rhusiopathiae Clinical Significance
GPR, pleomorphic, Non-spore forming, Catalase negative
What are the key biochemical reactions that identify Erysipelothrix rhusiopathiae?
Two gram stain morphologies (GPR), two colony types on SBA, catalase negative, H2S positive, test-tube brush pattern in motility tube, sucrose non“F”
• Two types– Long slender GPR in chains– Short GPCB
• Non-sporulating
Click icon for audio
Lactobacillus speciesGram Stain
GPR, pleomorphic, Non-spore forming, Catalase negative
• Grows on BAP– Multiple colony morphologies– Nonhemolytic or alpha hemolytic
• Microaerophilic
Click icon for audio
Lactobacillus speciesColony Morphology
GPR, pleomorphic, Non-spore forming, Catalase negative
• Catalase negative• Sucrose “F”• Vancomycin “R”
Click icon for audio
Lactobacillus speciesIdentification
GPR, pleomorphic, Non-spore forming, Catalase negative
Lactobacillus speciesClinical 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
• Actinomycetes– Nocardia species– Streptomyces species
Click icon for audio
Branching Nocardioform GPR
Nocardia speciesGram Stain
• Pleomorphic, branching, fine, delicate filaments with fragmentation GPR
• Often appears beaded
Click icon for audio
Branching Nocardioform GPR
• Grows on SBA, Mycology media and LJ media
• Aerobic growth appears at 3-30 days
• Waxy, bumpy or velvety rugose forms, yellow to orange colonies
Click icon for audio
Nocardia species Colony Morphology
Branching Nocardioform GPR
Nocardia species Identification
• Partially acid-fast positive• Presence of granules in specimen• Catalase
positive
Click icon for audio
Branching Nocardioform GPR
Nocardia species Clinical Significance
• Habitat: soil and water• Mycetoma (actinomycetoma)
– Tissue swelling– Draining sinus tracts– Presence of granules
• Immunocompromised patients– Pulmonary and disseminated infections
Click icon for audio
Branching Nocardioform GPR
What is the key characteristic in identifying Nocardia species?
Branching GPR that is partially acid fast positive
What primary disease does Nocardia cause and what 3 symptoms are seen?
Mycetoma (aka actinomycetoma). Triad of symptoms: tissue swelling, draining sinus tracts, and the presence of granules
• GPR with extensive branching, chains and spores
• Does not fragment easily
Click icon for audio
Streptomyces speciesGram Stain
Branching Nocardioform GPR
Streptomyces species Colony Morphology
• Grows on SBA, Mycology media and LJ media
• Aerobic growth appears at 3-30 days• Waxy, bumpy or velvety
rugose forms, yellow to orange colonies
Click icon for audio
Branching Nocardioform GPR
• Acid-fast negative
Click icon for audio
Streptomyces species Identification
Branching Nocardioform GPR
Streptomyces species Clinical Significance
• Habitat: soil and decaying vegetation• Mycetoma (actinomycetoma)• Rarely:
– Pericarditis– Bacteremia– Brain abscess
Click icon for audio
Branching Nocardioform GPR
How can you differentiate Streptomyces from Nocardia?
Streptomyces is acid-fast negative and Nocardia is partially acid-fast positive
• Nonspore-forming GPR, catalase negative– Gardnerella species– Erysipelothrix species– Lactobacillus species
• Branching Nocardioform GPR– Nocardia species– Streptomyces species
Click icon for audio
Aerobic GPRSummary
Who am I?HBT media shows
beta-hemolysis
GramStain
Gardnerella vaginalisCauses Bacterial Vaginitis
Who am I?
BAP, growth at 2 days Gram Stain
Erysipelothrix rhusiopathiaeMotility Tube: “test-tube brush” pattern of growth
TSI
Who am I?
LJ agar at 1 week Gram Stain
Nocardia species
Causes Actinomycetoma
Acid Fast Stain