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MICROPARA LAB REVIEWER W HIGHLIGHT.pdf Flashcards
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MICROPARA LAB REVIEWER W HIGHLIGHT.pdf Flashcards
MICROPARA LAB REVIEWER W HIGHLIGHT.pdf Flashcards
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1
Question
Answer
2
Question
What does the presence of bubbles indicate in the catalase test for further identification of Gram-positive bacteria?
Answer
Production of oxygen gas by catalase
3
Question
Which bacteria are catalase positive among staphylococci and streptococci?
Answer
Staphylococci and Streptococci are catalase positive.
4
Question
What does a positive coagulase test indicate in bacteria identification?
Answer
Coagulase positive bacteria promote clotting of serum.
5
Question
Which bacteria are novobiocin sensitive and which are novobiocin resistant among staphylococci?
Answer
Sensitive: S epidermidis; Resistant: S saprophyticus.
6
Question
What are the three types of hemolysis observed in bacteria and their characteristics?
Answer
Alpha Hemolytic, Beta Hemolytic, and Gamma Hemolytic
7
Question
Alpha Hemolytic
Answer
Incomplete or partial hemolysis, green or brown color surrounding the colony, hydrogen production of the organism which destroys the red cells.
8
Question
Beta Hemolytic
Answer
Complete hemolysis, clearing or colorless zone around the colony, visualization enhanced by anaerobic conditions.
9
Question
Gamma Hemolytic
Answer
No hemolysis, no apparent change in color.
10
Question
Which bacteria are sensitive to optochin and which are resistant?
Answer
Sensitive: S pneumoniae; Resistant: Viridans strep.
11
Question
Which bacteria are sensitive to bacitracin and which are resistant?
Answer
Sensitive: Streptococcus pyogenes (Group A Strep); Resistant: Streptococcus agalactiae (Group B Strep).
12
Question
Describe the characteristics of Staphylococcus aureus in terms of gram staining, colony appearance, catalase, coagulase, and habitat.
Answer
Staphylococcus aureus is Gram-positive cocci in clusters, colonies beta hemolytic yellow or golden on blood agar, catalase positive, coagulase positive, salt-tolerant on mannitol salt agar (halotolerant). Its gold color is due to the pigment staphyloxanthin. It inhabits the human nose, anterior nares, and skin, and is transmitted through direct contact, fomites, and contaminated food. It causes diseases like gastroenteritis, toxic shock syndrome, scalded skin syndrome, skin infections, acute bacterial endocarditis, urinary tract infection, pneumonia, osteomyelitis, and septic arthritis.
13
Question
Describe the characteristics of Staphylococcus epidermidis in terms of gram staining, colony appearance, catalase, coagulase, and novobiocin sensitivity.
Answer
Staphylococcus epidermidis is Gram-positive cocci in clusters, colonies whitish non-hemolytic on blood agar, catalase positive, coagulase negative, novobiocin sensitive. It is part of the normal skin flora, transmitted through autoinfection and direct contact, and has the ability to adhere to artificial materials in the body such as catheters and prosthetic heart valves. It causes infected indwelling catheters and prosthetic heart valve endocarditis.
14
Question
Describe the characteristics of Staphylococcus saprophyticus in terms of gram staining, colony appearance, catalase, coagulase, and novobiocin sensitivity.
Answer
Staphylococcus saprophyticus is Gram-positive cocci in clusters, colonies whitish non-hemolytic on blood agar, catalase positive, coagulase negative, novobiocin resistant.
15
Question
What are the different Lancefield groupings of streptococci based on antigenic differences in C carbohydrates?
Answer
Group A: Streptococcus pyogenes; Group B: Streptococcus agalactiae; Group C: Streptococcus equisimilis, Streptococcus equi, Streptococcus zooepidemicus, Streptococcus dysgalactiae; Group D: Enterococci, Streptococcus bovis.
16
Question
Describe the characteristics of Streptococcus pyogenes in terms of gram staining, catalase, hemolysis, bacitracin sensitivity, and habitat.
Answer
Streptococcus pyogenes is Gram-positive cocci in chains, catalase negative, beta hemolytic, bacitracin sensitive, Lancefield group A. It inhabits the human throat, oropharynx, and skin, is transmitted through respiratory droplets, and causes diseases like pharyngitis, skin soft tissue infections (impetigo contagiosa, erysipelas, cellulitis, necrotizing fasciitis), scarlet fever, streptococcal toxic shock syndrome, acute rheumatic fever, and glomerulonephritis.
17
Question
Describe the characteristics of Streptococcus agalactiae in terms of gram staining, catalase, hemolysis, bacitracin sensitivity, and habitat.
Answer
Streptococcus agalactiae is Gram-positive cocci in chains, catalase negative, beta hemolytic, bacitracin resistant, Lancefield group B. It is CAMP test positive and inhabits the vagina, transmitted through transvaginal or transplacental routes. It causes urinary tract infections in pregnant women and neonatal pneumonia, sepsis, and meningitis.
18
Question
Describe the characteristics of Group D streptococci in terms of gram staining, hemolysis, Lancefield grouping, growth, habitat, and spectrum of diseases.
Answer
Group D streptococci are Gram-positive cocci in chains, catalase negative, gamma hemolytic colonies, Lancefield group D. They include Enterococcus, Streptococcus bovis. They grow in bile and hydrolyze esculin in bile esculin agar. They inhabit the human colon, urethra, and female genital tract, can be colonized, and may enter the bloodstream during gastrointestinal (GI) or genitourinary tract procedures. They cause diseases like UTI, biliary tract infections, and endocarditis.
19
Question
Describe the characteristics of Streptococcus pneumoniae in terms of gram staining, catalase, hemolysis, optochin sensitivity, and habitat.
Answer
Streptococcus pneumoniae is Gram-positive lancet-shaped cocci in pairs or chains, catalase negative, alpha hemolytic, no Lancefield classification. It is bile soluble and optochin sensitive, with a positive Quellung reaction. It inhabits the upper respiratory tract, transmitted via respiratory droplets, and causes diseases like pneumonia, otitis media, sinusitis, meningitis, and septic shock.
20
Question
Which species are included in viridans streptococci, and what are their characteristics?
Answer
Viridans streptococci include S mutans, S mitis, S sanguis, S salivarius, S anginosus. They are Gram-positive cocci in chains, catalase negative, alpha hemolytic, bile insoluble, and optochin resistant. They inhabit the oropharynx, enter the bloodstream during dental procedures, and cause diseases like dental caries, subacute bacterial endocarditis (SBE), and brain abscesses.
21
Question
What are the general characteristics of Bacillus spp. in terms of gram staining, spore formation, motility, and hemolysis?
Answer
Bacillus spp. are Gram-positive spore-forming rods in chains, aerobic, and motile except Bacillus anthracis. Spores are centrally located, and Bacillus anthracis is nonmotile. They exhibit non-hemolytic or wide zone of beta hemolysis.
22
Question
Describe the characteristics of Bacillus anthracis in terms of gram staining, morphology, spore formation, and habitat.
Answer
Bacillus anthracis is aerobic gram-positive boxcar-like rods, nonmotile, and spore-forming with a medusa head morphology. It has a dry ground glass surface and irregular edges with projections along lines of inoculation. It inhabits the soil and is transmitted by contact with infected animals or inhalation of spores from animal hair and wool, causing diseases like cutaneous anthrax, inhalational anthrax, and gastrointestinal anthrax.
23
Question
Describe the characteristics of Bacillus cereus in terms of gram staining, morphology, spore formation, motility, and spectrum of disease.
Answer
Bacillus cereus is aerobic gram-positive spore-forming rods, motile, and spores on grains such as rice survive steaming and rapid frying. It causes diseases like ophthalmia, food poisoning (emetic form, diarrheal form) implicated in various foods with different incubation periods and symptoms.
24
Question
Describe the characteristics of Clostridium tetani in terms of gram staining, morphology, spore formation, habitat, transmission, and toxin production.
Answer
Clostridium tetani is anaerobic gram-positive spore-forming rods with a terminal spore, resembling a tennis racket. It inhabits the soil and is transmitted through traumatic implantation into tissues with low oxygenation. It produces tetanus toxin (tetanospasmin) causing tetanus.
25
Question
Describe the characteristics of Clostridium botulinum in terms of gram staining, morphology, spore formation, habitat, transmission, and pathogenesis.
Answer
Clostridium botulinum is anaerobic gram-positive spore-forming rods found in bulging cans, transmitted through improperly preserved food. It produces botulinum toxin, a neurotoxin that blocks acetylcholine release causing flaccid paralysis. It causes diseases like foodborne botulism, infant botulism (floppy baby syndrome), and wound botulism.
26
Question
Describe the characteristics of Clostridium perfringens in terms of gram staining, spore formation, hemolysis, habitat, and transmission.
Answer
Clostridium perfringens is anaerobic gram-positive spore-forming rods with double hemolysis on blood agar. It grows on egg yolk agar, nonmotile but with rapidly spreading growth on culture media. It inhabits the soil and human colon, causing myonecrosis from contaminated wounds and food poisoning transmitted by ingestion of contaminated food.
27
Question
Describe the characteristics of Clostridioides difficile in terms of gram staining, spore formation, exotoxin detection, habitat, and transmission.
Answer
Clostridioides difficile (formerly Clostridium difficile) is anaerobic gram-positive spore-forming rods with exotoxin detected in stool. It is carried in the colon, transmitted via the fecal-oral route, and causes diseases like pseudomembranous colitis and toxic megacolon.
28
Question
Describe the characteristics of Corynebacterium diphtheriae in terms of gram staining, morphology, culture appearance, habitat, transmission, and spectrum of disease.
Answer
Corynebacterium diphtheriae is aerobic non-spore-forming nonmotile gram-positive rods with club or comma-shaped rods arranged in V or L shapes. It has metachromatic granules and culture appearances like dark black colonies on potassium tellurite. It inhabits the human throat, transmitted via respiratory droplets, causing diseases like thick gray pseudomembranes over tonsils and throat, with complications like airway obstruction, myocarditis, and neural involvement.
29
Question
Describe the characteristics of Listeria monocytogenes in terms of gram staining, morphology, motility, hemolysis, habitat, transmission, and spectrum of disease.
Answer
Listeria monocytogenes is aerobic non-spore-forming gram-positive rods arranged in V or L shapes with tumbling motility and a narrow zone of beta hemolysis. It exhibits cold enhancement and colonizes the GI tract, female genital tract, animals, plants, and soil. It is transmitted across placenta or by contact during delivery, causing diseases like early onset neonatal listeriosis, late onset neonatal listeriosis, and adult listeriosis.
30
Question
What are the characteristics of Neisseria species in terms of gram staining, motility, oxidation test, culture appearance, and habitat?
Answer
Neisseria species are aerobic gram-negative nonmotile diplococci, with individual cocci kidney bean-shaped and oxidase test positive. They oxidize carbohydrates and grow on Thayer Martin agar with 5% chocolate sheep blood. They are found in the human genital tract and are transmitted by sexual contact or during passage through the birth canal.