PHMP LAB MIDTERMS

Smear

A thin film of a solution of microbes on a slide.

Stains

are salts consist of a positive and negative ion.

chromophore

the colored component of the compound.

basic dye

chromophore is cation

acidic dye

chromophore is an anion

simple stain

single basic dye is called?

mordant

may be used to hold the stain or coat the specimen to enlarge it.

wet mount technique

for motility

hanging drop technique

For size, shape, and types of motility

bacterial cell wall

is composed of a macromolecular network

peptidoglycan

marcomolecular network, also referred to as murein (murus means wall)

wall

murus means?

gram-positive

thick peptidoglycan layer with teichoic acid

gram-negative

thin peptidoglycan layer with lipopolysaccharide

Hans Christian Gram

developed in 1884 by? it is one of the oldest and most useful methods of staining bacteria

crystal violet

primary stain

gram’s iodine

mordant

95% ethyl alcohol

decolorizer

safranin

counter stain

gram positive

if they retained the primary stain after treatment with the mordant and decolorizer

gram negative

if they retain the 2nd stain

cocci

are gram (+), except Neisseria, Veinella,

Moraxella

bacilli

are gram (–) except Clostridium, Bacillus,

Corynebacterium, Lactobacillus, Listeria

monocytogenes, Erysipelothrix rhusiopathiae

yeasts

are gram positive

agar-disk diffusion

kirby-bauer technique also known as?

kirby-bauer technique

• Provides qualitative interpretive category results of

susceptible, intermediate, and resistant bacterial

isolates.

• Determines if bacteria is likely to be inhibited by an antimicrobial.

antibiotic-impregnated paper disk

uses of kirby bauer technique to test

whether particular bacteria are susceptible to

specific antibiotics.

zone of inhibition

an area of clearing surrounds the wafer where bacteria are not capable of growing

susceptible

• A bacteria is said to be sensitive to an antimicrobial

if there is significant zone of growth inhibition

around the disc.

• The antimicrobial is effective against the

microorganism and can be used for the treatment

of its infections

resistant

• A bacteria is ______ to the antimicrobial if there is

no significant zone of growth inhibition around the disc.

• The antibiotic is NOT effective against the microorganism. They will still grow even in the presence of the antimicrobial

Mueller-Hinton Agar

A microbiological growth medium that is commonly

used for antibiotic susceptibility testing.

• It is also used to maintain Neisseria and Moraxella species

Genus Staphylococcus

• Perfectly spherical cells about 1 micrometer in diameter

• Grow in clusters because staphylococci divide in two planes

• Vigorous catalase-producers

Hemolysis

Is the breakdown of RBC

Hemolysis Test

The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms.

Catalase Test

Is an enzyme that breaks H2O2 into H2O and O2 and the bubbling that is seen is due to evolution of O2 gas.

Coagulase

Are enzymes that clot blood plasma by a mechanism that is like normal clotting.

Coagulase Test

• The coagulase test identifies whether an organism produces this exoenzyme.

• This enzyme clots the plasma component of blood.

Staphylococcus aureus

The only significant disease-causing bacteria of humans that produce coagulase enzyme is?

S. aureus

this enzyme is a good indicator of the pathogenic potential

Mannitol Fermentation Test

The bacteria in the colonies capable of fermenting the mannitol in the medium to acid, cause a change of color.

S. aureus

• This forms a large yellow colony on rich medium.

• It is often hemolytic on blood agar.

• They are facultative anaerobes that grow by aerobic respiration or by fermentation that yields principally lactic acid.

Fibrin/fibrinogen binding protein

promotes attachment to blood clots and traumatized tissue adhesin.

Coagulase

coverts fibrinogen to fibrin and coagulates plasma.

Staphylokinase

lyses fibrin

Protein A

is a surface protein of S. aureus, which binds IgG molecules by their Fc region.

Leukocidin

is a toxin that specifically acts on polymorphonuclear leukocytes.

Enterotoxins

cause diarrhea and vomiting when ingested and are responsible for staphylococcal food poisoning.

Toxic Shock Syndrome Toxin-1 (TSST-1)

is expressed systemically and is the cause of toxic shock syndrome (TSS).

Exfoliatin toxin (ET)

causes the scalded skin syndrome in neonates, which results in widespread blistering and loss of the epidermis.

Genus Streptococcus

• The Streptococci are gram-positive cocci that are arranged in pairs or chains during growth.

• The genus Streptococci includes many species, some of which are frank pathogens, and other are members of the normal flora of the oropharynx and gastrointestinal tract

Smith & Brown

based on hemolytic activities of strep.

Alpha

partial hemolysis (green zones)

Beta

full hemolysis (clear zones)

Gamma

no hemolysis (no change)

Lancefield classification

based on the presence of group specific carbohydrate antigen C polysaccharide.

Alpha

hemolysis is caused by hydrogen peroxide produced by the bacterium, oxidizing hemoglobin to green methemoglobin

Beta

Streptolysin, an exotoxin, is the enzyme produced by the bacteria which causes the complete lysis of red blood cells

Gamma

Do not cause hemolysis and rarely cause illness

Bacitracin Disc Test (Taxo A)

Used to distinguish Group A streptococci, from other streptococci

Optochin Test (Taxo P)

or ethylhydrocupreine

• is a chemical used in cell culture techniques for the presumptive identification of Streptococcus pneumoniae.

Growth on 6.5% NaCl

• Enterococci can withstand a high salt concentration than non-enterococci.

• Organisms that do not grow on NaCl 6.5% agar are not salt tolerant. E. faecalis, E. zymogenes, E. liquifaciens, and E. durans are among the Enterococcus species that are salt tolerant.

Bile-esculin Test

is widely used to differentiate Enterococci and non- enterococcus group D streptococci.

Dick’s Test

Skin test used to diagnose S.pyogenes infection

Francis Test

Skin test used to determine presence of antibodies against pneumococci

Sore throat, glomerular nephritis

inflammation of the nephrons in the glomerular tube of the kidney, sepsis, Scarlet fever

Genus Neisseria

Bacteria of this genus are aerobic, fastidious, gram- negative cocci that usually inhabit the mucous membranes of mammals.

Gonococcus

(N. gonorrhoeae), the causative agent of gonorrhea

Meningococcus

(N. meningitidis) the agent of meningococcal meningitis

Growth on Modified Thayer Martin

An improvement of the Chocolate Agar formulation by the addition of antimicrobial agents which suppressed the growth of some contaminating organisms. Trimethoprim lactate was shown to be of value in the suppression of Proteus spp.

Neisseria gonorrheae

Is a species of Gram- negative coffee bean- shaped diplococci bacteria responsible for the sexually transmitted infection gonorrhea.

Ophthalmia neonatorum

Neonatal conjunctivitis, is a form of conjunctivitis contracted by newborns during delivery.

Ophthalmia neonatorum

Tx:

1% tetracycline ointment

0.5% erythromycin ointment

or

1% silver nitrate solution

ceftriaxone 50 mg/kg IM or IV

Neisseria meningitidis

Is a gram negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis.

Waterhouse-Friderichsen Syndrome

Massive adrenal hemorrhage in the setting of overwhelming clinical sepsis—is usually taken at necropsy to indicate meningococcal infection.

Genus Moraxella

Members of the _____ are strictly aerobic coccobacilli – that is, intermediate in shape between cocci and rods.

Moraxella lacunata

is implicated in conjunctivitis, an inflammation of the conjunctiva, the membrane that covers the eye and lines the eyelids.