click below
click below
Normal Size Small Size show me how
Micro Final exam rev
Question | Answer |
---|---|
Define morphology | forms & structures of bacteria cells |
Identify the 3 common morphologies of bacteria | cocci-spherical/bacilli-rod/spirochetes-helical |
Gram staining is based on | differences in cell walls |
Define aerobic | growth with oxygen |
Define anerobic | growth without oxygen require carbon dioxide for growth |
Define capnophilic | organism that require increased co2 (5-10%) |
Most bacteria grow best at what temp | 35-37 degrees C |
Identify and define each type of hemolysis | gamma - no hemolysis; alpha - incomplete hemolysis w/greenish around the bacteria colonies; beta - complete lysis of red cells; alpha prime - zone of alpha surrounded by beta hemolysis |
What defensive mechanisms are used by humans to guard against infection | intact skin - mucous membranes, mucous membrane cleansing activity and production of antimicrobial substances, phagocytosis |
Define nosocomial | healthcare facility acquired infection |
Define antigen | macromolecules that induce formation of antibodies |
Define antibody | immunoglobin; protein molecules produced in response to antigens |
What biochemical test divides staphylococci into 2 groups | coagulase |
What are the characteristic gram stain and morphology for staphylococci | gram pos cocci in grape-like clusters |
What is the principle of catalase testing | hydrogen peroxide breakdown into water & oxygen and creates bubbles |
Describe the general characteristics of Streptococci | catalase-neg; gram-pos cocci in chains |
What are the four systems for naming streptococci | serogrouping, physiologic properties, hemolytic activity, & common names |
Describe the colony morphology & hemolysis for GAS | small, translucent, with a large beta hemolytic zone |
What is a Zone of Inhibition | zone of no growth around antibiotic disk |
Describe the colonial morphology and hemolysis of GBS | large, flat, creamy, small zone of hemolysis |
What are the two important human pathogens in Bacillus species | bacillus anthracis and bacillus cereus |
Anthrax is caused by | bacillus anthracis |
What organism have been described as resembling Chinese letters on gram stain | corynebacterium spp. |
On gram stain, this organism is gram positive, rods with what appears as "holes" doe to what | bacillis - holes are spores and spores don't stain |
What test can be used to differentiate Listeria from GBS | bile-eoculin & catalase test |
What organism stains irregularly and appears as "beading" cocci | nocardia spp. |
Describe the gram and microscopic morphology of Neisseria | aerobic gram neg, diplococci in a kidney or coffee bean shape |
Describe the specimen transport requirements for N. gonorrhoeae | Direct inoculation, nonnutritive transport media, nutritive transport systems (JEMBEC) |
What type of culture media might be used to isolate N. gonorrhoeae | CHOC, NYC, JEMBEC, ML, & MTM |
Describe the colony morphology for N. gonorrhoeae | smooth, gray to white, T1&T2 - small & raised; T3,T4&T5 larger and flatter |
Identify 3 tests that may be used to assist in the id of gram negative cocci | gram stain, oxidase test, carbohydrate utilization, nitrate reduction, & nucleic acid probe |
Which Neisseria species uses lactose | N. lactomiea |
General characteristics of Haemophilus include | pleomorphic, gram-neg rods; x, v or both factor, blood loving, hemophilus rapid test, mousy odor |
Which strain of Haemophilus has a vaccine to prevent it | H. influenzae biogroup aegyptius |
What culture conditions are required for Haemophilus | capnophilic, increased co2 (5-10%), humidified atmosphere |
What Haemophilus has been described as a "school of fish" arrangement | H. ducreyi |
What growth factors are required for Haemophilus | x,v or both factors |
This family of organisms is commonly referred to as "enterics" | enterobacteriaceae (reduces nitrate to nitrite and oxidase neg) |
General characteristics of Enterbacteriaeceae include | Gram-neg bacilli with straight sides and rounded ends w/bipolar staining and metabolizes glucose |
What culture media can be used for Enterbacteriaeceae | BAP, EMB, MAC, XLD, CIN, SS, and HE |
Describe each of the four enteric antigens | H-on flagella/ O antigen- somatic body, part of cell wall, component of endotoxin/K antigen- capsular/ Vi - capsular in some strains of salmonella / H and K are heat labile |
What is the most common Klebsiella isolate | K. pneumoniae |
Describe the colonies of Klebsiella | mucoid, string forming on MAC & EMB |
What are two distinguishing characteristics of Proteeae | burned chocolate smell and swarming growth pattern |
Describe the causative agent of plague | Y. pestis |
What organism appears as "bull's eye" on CIN agar | Y. enterocolitica |
Describe 5 different media that may assist in identification of enterics | EMB, MAC, SS, HE, XLD |
Name 3 specific identification tests for enterics | Carb. utilization, ONPG test, H2S production on TSI or KIA |
What biochemical reactions can be determined using a KIA tube | glucose and lactose fermentation and the production of H2S and gas |
Several key characteristics of NFB are | no spores & cant breakdown carbohydrates under anaerobic conditions (nonfermenters) |
When should you suspect a NFB | oxidase-pos, alkaline/nochange reaction in TSI or KIA |
What identification tests are useful in identifying NFB isolates | oxidative-fermentive (of) test, oxidase test, and growth on mac |
Key characteristics of Pseudomonads are | growth on MAC, oxidizes glucose, reduces nitrate and oxidase-pos |
Colonies of P. aeruginosa appear how | large, irregular shape, metalic sheen, mostly produce pyocyanin (blue pigment) |
Typical identification results for P. aeruginosa are | gram-neg rods, oxidase and pyocyanin pos, alkaline/no change TSI & KIA reaction, and grows @ 42 degree C |
How do Acinetobacter colonies appear on MAC | colorless to slightly pink |
Key id tests results for Acinetobacter include | Oxidase-neg, nitrate-neg, catalase-pos, motility-neg |
Key characteristics of Moraxella are | gram-neg cocci, oxidase-pos, glucose-neg, motility-neg, penicillin-suseptible |
Describe the gram stain result and morphology of Vibrio | straight to slightly curved gram-neg rods. |
How are V. cholerae divided into serogroups | "o" or cell wall antigens |
Identify 3 id tests that may be used to differentiate Vibrio and Aeromonas | Suseptibility, Salt requirement and tolerance test, and String test (0.5% deoxycholate) |
Biochemical test results for Vibrio include | indole-pos, nitrate-pos, voges proskauer-pos, carb utilization-pos |
Describe the gram stain result & morph of H. pylori | gram-neg rods, S-shaped |
H. pylori is the causative agent of what illness | chronic gastritis, peptic and doudenal ulcers |
What organism causes whooping cough | bordetella pertussis |
The preferred specimen for isolating B. pertussis are | nasopharyngeal swabs and aspirates |
Where is Legionella commonly found | lakes, rivers, soil, mud, air conditioning cooling towers |
Describe the gram stain result and morph of Legionella | faintly staining gram-neg rods |
What diseases are caused by Legionella | legionaires disease & pontiac fever |
What organisms are described as having a "fried egg" appearance | streptobacillus |
This organism has a "bleachlike" odor | eikencella corroidens |
Define anaerobic | growth in the absence of oxygen o2 |
Define facultative anaerobe | growth in the absence or presence of oxygen |
Define obligate anaerobe | requires anaerobic conditions oxygen and its derivatives are toxic to them |
How are anaerobic bacteria able to survive in the body | facultative organisms use up the oxygen in protected areas and reduce the redox potential and inactivate harmful oxygen-based molecules |
What causes exogenous diseases | organisms from outside the body |
What causes endogenous infections | organisms inside the body |
Anaerobic bacterial infections are suspected when what clues are present | an infection near a mucosal surface, foul smelling, or gaseous discharge and necrotic tissue |
What 3 anaerobic bacteria are responsible for most human disease | bacteroides fragilis group, pigmented prevotella spp., porphyromonas spp., fusobacterium nucleatum, clostridium perfringens and anaerobic cocci |
What id tests are used for anaerobic bacteria | growth stimulation test, lecithinase, nagler test, aerotolerance, colony and gram morph, conventional biochemical tube |
Describe the gram stain result for Clostridium | gram-variable coccoid to filamentous |
Where are terminal spores found | at one end of the bacterial cells |
What infections are caused by C. perfringens | bacteremia, cellulitis, intra-abdominal abscesses, female genital tract infections, and myonecrosis (gas gangrene) |
Describe the gram stain morph of C. perfringens | gram-pos boxed-car shaped rods |
Describe the hemolysis pattern of C. perfringens on anaBAP | a double zone of beta hemolysis on anaBAP |
C. difficile produces what toxins | enterotoxin - toxin A cytotoxin - toxin B |
What organism causes botulism | clostridium botulinum |
What actinomycetes most commonly causes disease | a. israelii |
For direct examination for actinomycetes, what should be examined and for what | Pus- for sulfer granules |
What is the most commonly isolated bacteroides | b. fragilis |
Describe the gram stain morph of bacteroides | faintly staining gram-neg rods w/round ends |
Prevotella are resistant to what antibiotics | kanamycin and vancomycin |
General characteristics of Mycobacteria include | aerobic, non-spore forming, non-motile rods that are usually straight to slightly curved |
Why is routine gram stain not recommended for Mycobacteria | they stain poorly because their cell wall lipids interfere w/the penetration of crystal violet and safrain into the cell |
How is M tuberculosis transmitted | inhalation of droplet nuclei |
What is the causative agent of leprosy | M. leprae |
What are the two most common acid fast stains used for mycobacteria | carbdfuchsin-based and fluorochrome-based stains |
What type of culture media might be used to grow mycobacteria | egg-based, agar based, liquid or bifasic culture media |
What are the five groups that mycobacteria can be divided into based on rate of growth, colonial morphology and ability to produce pigment | rapid or slow growers, colonial morph, photochromogin, scotochromogen, and non photochromogen |
What biochemical tests are used in identifying mycobacteria | arylsulfatase, catalase, semiquantitative catalase, drop method, iron uptake, special mac, and tellurite reduction |
Antimicrobial susceptivility tests should be performed on which mycobacteria growths | all initial isolates |
Describe the general characteristics of chlamydiae | non-motile gram-neg obligate intracellular parasites |
How are most chlamydia organisms identified | licopolysaccharide & major outer membrane protein (MOMP) |
Describe the general appearance of spirochetes | long slender spiral shape |
What is the causative agent of Lyme disease | borrialla dorphri |
What type of lab tests are mose often used to diagnose Lyme disease | serological |