Microorganisms🔍
What do you need to use in order to see microorganisms?
Microscope
Gram-positive lancet-shaped diplococci with a polysaccharide capsule.
Streptococcus pneumoniae
On MacConkey agar, colonies are colorless. On TSI agar, there is H₂S production (black precipitate).
Salmonella enterica
What can kill bacteria?
Antibiotics
A 22-year-old presents with dysuria and purulent urethral discharge. Gram-negative diplococci are seen inside neutrophils. The organism is oxidase positive and ferments glucose but not maltose.
Neisseria gonorrhea
98.6
Gram-positive rods arranged in “Chinese letter” or palisading patterns due to snapping division.
Corynebacterium diphtheriae
On MacConkey agar, you see bright pink colonies. The organism is oxidase negative and indole positive.
E. coli
Makes up around 80% of all UTIs
What is E coli
A patient with a prosthetic heart valve develops endocarditis. The organism is catalase negative, grows in bile, and hydrolyzes esculin.
Enterococcus faecalis
What does it mean to be able to live with oxygen?
Aerobic
Gram-negative kidney-shaped diplococci found intracellularly in neutrophils.
Neisseria gonorrhoeae
Grows on Thayer-Martin agar. Gram-negative diplococci, oxidase positive.
Neisseria gonorrhea
What bacteria cause most nosocomial infections?
Staphylococcus aureus
An elderly alcoholic presents with pneumonia producing “currant jelly” sputum. The organism is a lactose fermenter, urease positive, and has a thick capsule.
Klebsiella pneumoniae
What helps microorganisms move?
Flagella
Large Gram-positive rods arranged in chains, non-motile, spore-forming.
Bacillus anthracis
A swarming organism on blood agar with concentric rings. Urease positive and produces a strong ammonia odor.
Proteus mirabilis
Produces shiga toxin that inactivates the 60S ribosomal subunit, leading to bloody diarrhea and HUS.
Shigella dysenteriae
A farmer presents with a painless black eschar on the hand. The organism is a Gram-positive spore-forming rod with a capsule.
Bacillus anthracis
What term is used to describe organisms that require special nutritional and environmental needs in order to grow?
Fastidious
Gram-negative coccobacilli with bipolar (“safety pin”) staining seen on Wright or Giemsa stain.
Yersinia pestis
On Sabouraud agar, you see creamy yeast colonies. Germ tube test is positive.
Candida Albicans
Produces an exfoliative toxin causing scalded skin syndrome in children. Gram-positive cocci in clusters.
Staphylococcus aureus
A man just got back from a vacation in Fiji. He has intense stomach pain and frequent diarrhea. A stool culture was preformed and the plates were overgrown with swarmer's. However, the CampyBAP was growing a large yellowish colony and a large grey. Oxidase and a gram stain was done on both colonies:
Yellow = OX pos, Curved GNB
Grey = OX neg, GNB
Most probable ID?
Vibrio spp.