Catalase Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Catalase and links to relevant pages within the course.
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|The Superoxol Test|
Superoxol is an additional spot test that may be helpful in the presumptive identification of N. gonorrhoeae. Superoxol is 30% hydrogen peroxide, in contrast to the 3% solution that is used in the catalase test. Other Neisseria species and Moraxella catarrhalis are either negative for this test or give a weak, delayed reaction.
|The bacterial cells shown in the image were observed in a smear prepared from the colony shown before. Which of the following tests will help to affirm the identification of Staphylococcus aureus?||View Page|
|Most strains of S. anginosus (milleri) carry the F antigen (see image). Rare strains that carry the group A antigen can be differentiated from S. pyogenes by which of the following laboratory tests:||View Page|
|Beta hemolytic colonies grew from the blood culture bottle after 18 hours incubation (see image). Which of following tests would be helpful in making a preliminary identification? (Choose all that apply)||View Page|
|What test(s) which may be performed to establish a presumptive differential identification between group B streptococci and L. monocytogenes?||View Page|
|Eikenella - Catalase & Oxidase|
Eikenella corrodens (E) belongs to the HACEK group of miscellaneous gram-negative bacilli which includes Haemophilus aphrophilus (H), Actinobacillus actinomycetemcometans (A), Cardiobacterium hominis (C) and Kingella kingae (K). Cytochrome oxidase and catalase are two rapid tests that help separate the several members of this group. Eikenella corrodens shows cytochrome oxidase activity, but not catalase activity. The positive oxidase reaction separates E. corrodens from Haemophilus aphrophilus and Actinobacillus actinomycetemcomitans, which are both negative. A. actinomycetemcomitans is also catalase positive, an additional characteristic separating it from E. corrodens, which is negative. As Kingella kingae is also oxidase positive and catalase negative, other tests are needed for differentiation. K. kingae produces acid from glucose and maltose (E. corrodens is asaccharolytic).
|A bacterial isolate that produces pitting of the agar and has a bleach-like odor is probably E. corrodens. What are the closely related species that must be ruled out? (Choose all that apply)||View Page|
|Different species of Neisseria can be differentiated from each other by:||View Page|
|Staphylococcus aureus Virulence Factors|
S. aureus is the most pathogenic member of the genus Staphylococcus; it possesses several factors that contribute to its virulence: Structural components of its cell wall function as a protective barrier, aid in adherence to mucous membranes, and allow the organism to resist phagocytosis. The production of several different toxins Enterotoxins A, D, F (TSST1) Exfoliative toxin ( causing scalded skin syndrome Cytolytic toxins (causing cell & tissue damage). Production of enzymes Catalase – distinguishes staphylococci from streptococci Coagulase – distinguishes S. aureus from other staphylococci Hyaluronidase & lipase – aid in skin colonization/infection spread Beta-lactamase – breaks down the beta-lactam antibiotics, e.g., penicillins, cephalosporins, carbapenems and monobactams.
|Assume you perform microbiology for an institution submitting surveillance cultures for MRSA. Which isolate should receive further workup to rule out methicillin (oxacillin) resistance?||View Page|
|Identification of Enterococcus species from clinical cultures|
Gram stain: gram-positive cocci in singles, pairs, or chains; cells can be ovoid to coccobacillaryColony morphology: on blood agar after 24 hours of incubation, colonies are nonhemolytic or alpha hemolytic (rare strains may be beta hemolytic), and approximately 1 to 2 mm in diameter.Catalase: negativePresumptive identification: Growth on bile esculin agar and in 6.5% salt broth are two characteristics that have commonly been used to identify Enterococcus to the genus level. A positive esculin in combination with a positive PYR reaction is another approach to presumptive identification.Species identification: E. faecalis and E. faecium are usually easily identified by most commercial systems. Successful identification of the other species on these systems may vary. With respect to vancomycin intermediate or resistant strains, two key characteristics are motility and pigment. E. casseliflavus is both motile and possesses a yellow pigment; E. gallinarum is also motile but non-pigmented. E. faecalis and E. faecium demonstrate neither characteristic.
|Which of the following statements reflect accurate identifications of Enterococcus species?||View Page|
Motility:Motility by wet preparation is NOT recommended. Motility medium is more reliable, but shouldn't be read until 18-24 hours. Bacillus anthracis is non-motile Bacillus cereus is motileCatalase:Bacillus species are catalase positive. Catalase testing MUST be performed in a biosafety cabinet (BSC) due to the creation of aerosols.India Ink:India ink can reveal the capsule but testing is NOT recommended.
Yersinia pestis is a dangerous, highly virulent organism that can cause laboratory-acquired infections. It should NOT be manipulated on an open bench.Catalase: Y. pestis is catalase positive. Catalase testing MUST be performed with extreme caution in a biosafety cabinet (BSC) due to the creation of aerosols. Oxidase: NegativeUrea: NegativeIndole: NegativeImportant note: Y. pestis is often incorrectly identified on automated identification systems. These systems often key out as Acinetobacter, Shigella, or an H2S negative Salmonella. If this organism is suspected, do NOT use an automated system for identification in order to prevent the creation of aerosols and misidentification.
Francisella tularensis is a dangerous, highly infectious organism that can cause laboratory-acquired infections. It should NOT be manipulated on an open bench.Catalase: F. tularensis is weakly catalase positive. Catalase testing MUST be performed with extreme caution in a biosafety cabinet (BSC) due to the creation of aerosols. Oxidase: NegativeBeta-lactamase: PositiveUrease: NegativeXV factors: Not required for growthImportant note: F. tularensis is often incorrectly identified on automated identification systems. These systems may key out as Haemophilus influenzae or Actinobacillus species.
Brucella is a dangerous, highly virulent organism and the aerosols are highly infectious. It is the MOST common cause of laboratory-associated bacterial infections. Laboratory acquired cases have occurred by aerosol generating procedures, direct skin contact with cultures, and by sniffing cultures. It should NOT be manipulated on an open bench.Catalase: Brucella is catalase positive. Catalase testing MUST be performed with extreme caution in a biosafety cabinet (BSC) due to the creation of aerosols. Oxidase: PositiveBeta-lactamase: PositiveUrease: PositiveXV factors: Not required for growth (satellite phenomenon with S. aureus is negative)Serological testing: Often used because so difficult to grow. An acute and convalescent phase specimen should be collected 21 days apart.
Burkholderia species is a dangerous and highly virulent organism that can cause laboratory-acquired infections. It should NOT be manipulated on an open bench.Catalase: Both organisms are catalase positive. Catalase testing MUST be performed with extreme caution in a biosafety cabinet (BSC) due to the creation of aerosols. Oxidase: B. mallei: Oxidase variable B. pseudomallei: Oxidase positiveIndole: Both organisms are indole negativeMotility: B. mallei: Non-motile B. pseudomallei: Motile
|Which of the following is NOT a characteristic of Burkholderia pseudomallei?||View Page|
Any isolate with the following features should be immediately referred to your LRN reference laboratory: Gram stain shows large, gram-positive rods with sub-terminal or central spores (if present) Gray colonies with a ground glass appearance Non-hemolytic on sheep blood agar (SBA) Tenacious or "sticky" colonies like petroleum jelly Catalase positive Non-motile
Any isolate with the following features should be immediately referred to your LRN reference laboratory: Gram stain shows fat, gram-negative rods in single or short chains that may demonstrate bipolar staining Faster growth at 25oC Gray-white, translucent colonies on sheep blood agar (SBA) at 24 hours that turn slightly yellow and opaque at 48 hours Irregular colonies that have a "fried egg" and/or "hammered copper" appearance after 48-72 hours Catalase positive Oxidase negative Urea negative Indole negative
Any isolate with the following features should be immediately referred to your LRN reference laboratory: Gram stain demonstrates tiny, faintly staining gram-negative organisms that may stain gram-positive Slow growing, convex, non-hemolytic, non-pigmented colonies Catalase positive Oxidase positive Urea positive
Any isolate with the following features should be immediately referred to your LRN reference laboratory:B. mallei: Gram stain that reveals pale staining straight or slightly curved gram-negative coccobacilli Cells arranged in end-to-end pairs, parallel bundles, or Chinese letter form Smooth, gray, translucent colonies on sheep blood agar (SBA) at 48 hours Catalase positive Oxidase variable Indole negative Non-motileB. pseudomallei: Gram stain shows slender gram-negative rods with bipolar staining Smooth form appears in Gram stain as long parallel bundles Rough form appears in Gram stain in an irregular arrangement Smooth, creamy, white colonies on SBA at 24 hours Dry, wrinkled colonies at 48-72 hours Catalase positive Oxidase positive Indole negative Motility positive
The cytoplasm of eosinophils is evenly filled by numerous orange-red granules of uniform size. They do not overlie the nucleus. The eosinophil granules contain numerous enzymes including peroxidase, phospholipase D, catalase, acid phosphatase, and vitamin B12-binding proteins. The eosinophil's ability to kill bacteria is less than that of neutrophils. Their main purpose is to counteract parasitic infections and to participate in immune allergic reactions. They may also be increased in a variety of nonimmunologic inflammatory responses from bacteria and fungi causing chronic infections. Malignancies, collagen vascular diseases, and myeloproliferative disorders may also may be settings for prominent eosinophils.