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Unit 3 Chapter 16

Aerobic Gram-Positive Bacill

general characteristics of Corynebacterium large diverse group of bacteria that includes animal and human pathogens as well as saprophytes and plant pathogens. There are more than 80 species in this genus with at least 50 that are clinically significant. Normal biota on skin and mucus membrane.
C. diphtheria *colony morphology* nonmotile, nonsporing, produces acid from glucose and malltose fermentation, no acid from sucrose
C. diphtheria *gram stain results* gram-positive rod that appears in palisades or as individual cells lying at sharp angles to another in "V" and "L" formation
C. diphtheria *testing results* negative for urease, pyrszinamidase, and alkaline phosphatase
C. diphtheria *virulence factors* diptheria toxin
C. diphtheria *epidemiology* spread by droplets, secretions, or direct contact. Infection is spread solely among humans, although toxigenic strains have been isolated from horses.
C. diphtheria *infections* respiratory and cutaneous diptheria
other Corynebacteria and any identifiers amycolatum- Flat, dry, matte or waxy appearance nonlipophilic. jeijeium- aerobe, nonhemolytic. pseudodiphtheriticum-palisades. pseudotuberculosis-small yellowish-white colonies. striatum-nonlipemic, pleomorphic, small shiny, convex colonies. ulcera
Rothia *colony morphology* resembles coryneform bacilli but also branching filaments that resemble filaments of faculative actinomycetes
Rothia *gram stain results* gram-positive cocci
Rothia *testing results* nitrate-positive, nonmotile, esculin hydrolisis-positive, and urease-negative. Approximately two third of the isolates are catalase-positive.
Rothia *virulence factors* none
Rothia *epidemiology* member of normal human oropharyngeal microbiota may be found in saliva and supragingival plaque
Rothia *infections* endocarditis, bacterimia, pneumonia, and other infections.
Listeria monoctogenes *colony morphology* may be found singly, in short chains, or in palisades, , colonies are small, round, smooth, and translucent, narrow zone of β-hemolysis
Listeria monoctogenes *gram stain results* gram-posotive coccobacillus, older cultures often appear gram-variable.
Listeria monoctogenes *testing results* catalase-positive, motile at room temperature, hydrolizes esculin, hippurate hydrolisis and bile esculin-hydrolisis-positive and produces a positive CAMP reaction.
Listeria monoctogenes *virulence factors* hemolysin (listeriolysin O), catalase, superoxide dismutase, phospholipase C, and a surface protein (p60).
Listeria monoctogenes *epidemiology* widespread in the environment has been recovered from the soil, water, vegetation and animal product, such as raw milk, cheese, poultry, and processed meats. has been isolated from crustaceans, flies, and ticks.
Listeria monoctogenes *infections* listerosis can result in spontaneous abortion and still births in pregnant women, neonate cases are extremely fatal or manifest as meningitis, invasive listeriosis occurs with immunosuppressed individuals manifests as CNS infection and endocarditis
Motility testing *principle* semisolid medium designed to detect bacterial motility. Its agar concentration is reduced from the typical 1.5% to 0.4%- just enough to maintain its form while allowing movement of motile bacteria.
Motility testing *reagents* tetrazolium salt; 2,3,5-Triphenyltetrazolium chloride
Motility testing *results reporting* positive- red radiating outward; negative- red only along stab line
Motility testing *additional* motility is detectable as diffuse growth radiating from the central stab line.
Esculin Hydrolysis *principle* The purpose is to see if the microbe can hydrolyze the compound esculin as a carbon source.
Esculin Hydrolysis *medium* Usually, the medium used is bile esculin agar slant. This is a nutrient agar-based medium containing 0.1% esculin and 10% bile salts, and allowed to solidify at a slant.
Esculin Hydrolysis *results reporting* Abundant growth on the slant indicates a positive test for growth in the presence of bile. If growth is present, esculin hydrolysis can be observed if the medium has taken on an intense, chocolate brown coloration.
Acid from glucose *principle* The purpose is to see if the microbe can ferment the carbohydrate (sugar) glucose (also known as dextrose) as a carbon source.
Acid from glucose *reagents* Most commonly used is phenol red glucose broth. The medium is a nutrient broth to which 0.5-1.0% glucose is added; also contains a Durham tube, a smaller inverted tube which can serve as a trap for gas bubbles generated during fermentation of sugars.
Acid from glucose *results reporting* The pH indicator phenol red is red at neutral pH but turns yellow at pH <6.8. Is magenta or hot pink at pH >8.4; The culture changes to yellow in the presence of acids (positive) and magenta or hot pink in the presence of bases/alkali (negative).
Acid from glucose *additional* If glucose (dextrose) is fermented to produce acid end products, the pH of the medium will drop. A pH indicator in the medium changes color to indicate acid production.
Nitrate reduction *principle* Anaerobic respiration involves the reduction of an inorganic molecule other than oxygen. Nitrate reduction is one such example.
Nitrate reduction *reagents* nitrate broth, sulfanilic acid, and α-naphthyamine
Nitrate reduction *results reporting* red color formation- nitrate to nitrite no color change- nitrite was not reduced or was reduced to one of the other nitrogenous compunds
Urease *principle* used to differentiate organisms based on their ability to hydrolyze urea with the enzyme urease.
Urease *reagents* urease, peptone, potassium phosphate, glucose, phenol red, and agar Peptone and glucose to provide nutrients
Urease *results reporting* Agar: all pink- positive, partially pink- weak positive (24 hrs); (24 hrs to 6 days) orange or yellow to partially pink- weak positive. orange or yellow-negative. Broth: pink- positive; orange or yellow- negative
Gardnerella vaginalis *colony morphology* short, pleomorphic, β-hemolytic, small, gray and opaque- on human blood, pinpoint nonhemolytic -on SBA
Gardnerella vaginalis *gram stain results* gram-positive rod or coccobacillus that often stain gram-variable or gram-negative
Gardnerella vaginalis *testing results* catalase-negative, oxidase-negative, hippurate-hydrolysis-positive
Gardnerella vaginalis *virulence factors* thin peptidogycan layer
Gardnerella vaginalis *epidemiology* normal biota in the human urogenital tract
Gardnerella vaginalis *infections* bacterial vaginosis in humans
Nocadia *colony morphology* aerobic, branched, beaded, resemble fungi
Nocadia *gram stain results* grm-positive bacilli
Nocadia *testing results* substrate hydrolysis, antimicrobial susceptability profile, fatty acid analysis by high-performance liquid chromatography. 16srRNA gen sequencing most reliable method
Nocadia *virulence factors* none identified, have been correlated with alterations in the components cell wall
Nocadia *epidemiology* commonly found in soil
Nocadia *infections* pulmonary and cutaneous
Actinomyces and their identifiers aerobic differentiated by metabolic variations; Streptomyces, Gordonia, Tsukamurella, Rhodococcus, Tropheryma whipplei
Bacillus anthracis *colony morphology* aerobic or facultative anaerobic form endospores
Bacillus anthracis *gram stain results* gram-positive or gram-variable bacilli
Bacillus anthracis *testing results* catalase-positive
Bacillus anthracis *virulence factors* glutamic acid capsule, three-component proteinexotoxin
Bacillus anthracis *epidemiology* plants contaminated with spores
Bacillus anthracis *infections* cutaneous, inhalation, gastrointestional
Bacillus cereus *colony morphology* hemolytic on SBA, motile, facultatively anaerobic, endospore-forming
Bacillus cereus *gram stain results* gram-positive rod
Bacillus cereus *testing results* lecithinase production, fermentation of salicin, produces acid from glucose, maltose; gelatinase-positive
Bacillus cereus *virulence factors* enterotoxin
Bacillus cereus *epidemiology* food poisoning and opportunistic infections in susceptible hosts
Bacillus cereus *infections* diarrhea, emetic
other Bacillus species and their identifiers Bacillus subtilis, Bacillus licheniformis, Bacillus circulans, Bacillus pumilus, and Bacillus sphaericus: reported to cause food poisoning, bacterimia, meningitis, pneumonia, and other infections. commonly seen as contaminants.
Created by: luceroapril