Session 5

growth of chemoautotrophs and photoautotrophs; microbiological assays

growth of most chemoheterotrophic organisms

growth of obligate anaerobes

suppression of unwanted microbes; encouraging desired microbes

differentiation of colonies of desired microbes from others based on different fermentation

general purpose media supplemented by blood or other special nutrients to favor growth of microorganisms (fastidious)

Differential: distinguishes based on ability to cause lysis of red blood cells (pattern of hemolysis)
- Alpha: partial hemolysis, greenish discolorization, streptococcus pneumoniae
- Beta: complete hemolysis, clearing of agar around colony, staphulicoccus aureus
- Gamma: no hemolysis, brownish color, staphulococcus epidermidis

Enriched: general purpose & enriched, supports growth of fastidious bacteria

General purpose medium: grows fastidious bacteria that need a nutritional environment

Enriched medium: cultures bacteria that doesn't grow easily like H. influenza

Differential medium: detects hemolysis by cytolytic toxins secreted by bacteria like bacillus

Selective: crystal violet and bile salts inhibit gram positive bacteria but select gram negative bacilli

Differential: gram negative bacilli can ferment lactose to form coliforms and turn pink like E. coli

Selective: high salt content inhibits streptococcus species but tolerates staphylococcus

Differential: pathogenic species of staphylococcus can ferment mannitol to turn yellow like Staphylococcus aureus

susceptibility or resistance to certain antibiotics can be used to identify some bacterial species

antibiotic sensitivity used to distinguish group A strep (streptococcus pyogenes) & group B strep (streptococcus agalactiae)

antibiotic sensitivity used to distinguish streptococcus pneumoniae from other resistant alpha hemolytic streptococcus

antibiotic sensitivity used to distinguish between staphylococcus species through zones of inhibition:
< 17mm = resistant
18-21mm = intermediate
> 22mm = susceptible

bacteria found in digestive tract of human and animals as waste, gram negative bacilli bacteria that ferment lactose

indicator of fecal contamination in water

Bacteria that are part of the normal flora of the intestines, associated with food-borne illnesses

1. Proper cooking of food (temperatures)
2. Prevent cross contamination of surfaces & utensils
3. Practice handwashing

Rapid identification of gram-negative enteric bacteria through 15 biochemical tests, positive reactions are totaled to compare to interpretation guide, confirms certain gram-negative diseases

- blood agar: beta hemolytic
- mannitol salt agar: grows in high salt & ferments in mannitol
- catalase
- novobiocin sensitivity: susceptible

- blood agar: beta or gamma hemolytic
- mannitol salt agar: grows in high salt & ferments in mannitol
- catalase
- novobiocin sensitivity: resistant

- blood agar: gamma hemolytic
- mannitol salt agar: grows in high salt & does NOT ferment in mannitol
- catalase
- novobiocin sensitivity: susceptible

- blood agar: beta hemolytic
- mannitol salt agar: does NOT grow in high salt
- NOT a catalase
- bacitracin sensitivity: resistant

- blood agar: beta hemolytic
- mannitol salt agar: does NOT grow in high salt
- NOT a catalase
- bacitracin sensitivity: susceptible

- blood agar: alpha hemolytic
- mannitol salt agar: does NOT grow in high salt
- NOT a catalase
- optochin sensitivity: resistant

- blood agar: alpha hemolytic
- mannitol salt agar: does NOT grow in high salt
- NOT a catalase
- optochin sensitivity: susceptible

- coliform
- found in intestines (normal flora)
- opportunistic pathogen
- causes UTIs & spread through contaminated food/water

- coliform
- found in intestines (normal flora)
- opportunistic pathogen
- causes pneumonia & meningitis, spread by direct contact

- NOT a coliform
- found in contaminated foods (NOT part of normal flora)
- true pathogen
- causes food poisoning, spread by contaminated foods

- coliform
- found in GI tract (normal flora)
- opportunistic pathogen
- causes sepsis if it gets into surgical wounds, spread by direct contact

- NOT a coliform
- found in intestines (NOT part of normal flora)
- true pathogen
- causes shigellosis (toxin), spread by direct contact/stool

- found in skin & GI tract (normal flora)
- opportunistic pathogen
- causes skin & soft tissue infection, sepsis, food poisoning, & TSS, spread by direct contact

- found in skin (normal flora)
- opportunistic pathogen
- causes wound infections in weakened immune systems, spread by contaminated medical devices

- found in bladder (NOT part of normal flora)
- true pathogen
- causes UTIs, spread by sex

- found in gut & GI tract (normal flora)
- opportunistic pathogen
- causes skin & soft tissue infection, sepsis, & meningitis, spread by direct contact

- found in mouth (normal flora)
- opportunistic pathogen
- causes tooth decay & cavities, spread by saliva

- found in nasopharynx (normal flora)
- opportunistic pathogen
- causes ear infections, sepsis, & pneumonia, spread by direct contact

- found in skin & throat (normal flora)
- opportunistic pathogen
- causes strep throat & upper respiratory infections, spread by direct contact