LECTURE 3 FINAL EXAM

Endospores

Hardest form of a bacterium to control.

Vegetative cells

Easiest form of a bacterium to control.

Sterilization

Removes all viable life, including endospores, from inanimate objects.

Disinfection

Removes vegetative cells only from inanimate objects.

Antisepsis

Removes vegetative cells; safe for use on body tissues.

Sanitization

Removes vegetative cells and debris; used only on inanimate objects.

Degermation

Removes vegetative cells and debris from body tissues.

Autoclave

Sterilization using heat, steam, and pressure.

Pasteurization

Disinfection of beverages to increase shelf life and maintain taste.

Dry heat sterilization

Sterilization method (e.g., flaming an inoculating loop).

Refrigeration/Freezing

Slows microbial growth.

Ionizing radiation

Penetrates surfaces and breaks DNA.

Non-ionizing radiation (UV light)

Does not penetrate surfaces; causes thymine dimers in DNA.

HEPA filter

Used to disinfect air.

Chlorine

Disinfects water (drinking, sewage, pools).

Iodine

Antiseptic on skin before surgery.

Chlorhexidine

Low-toxicity antiseptic/disinfectant; controls MRSA outbreaks.

Ethanol

Low-toxicity antiseptic/disinfectant; used in hand sanitizers or lab bench cleaning.

Hydrogen peroxide

Low-toxicity antiseptic/disinfectant; used in contact lens cleaners.

Glutaraldehyde

Sterilant for invasive equipment like endoscopes and dialysis machines.

Ethylene oxide

Gas sterilant for prepackaged materials.

Chlorine dioxide

Gas sterilant used for whole-room disinfection.

Quaternary ammonium salts

Used in disinfectants.

What are Antibiotics?

Natural drugs made by one microorganism to kill another.

First Antibiotic

Penicillin, isolated by Alexander Fleming.

Broad-spectrum drug

Treats a wide range of microbes.

Narrow-spectrum drug

Treats a limited range of microbes.

Selective toxicity

Drug kills the microorganism without harming the human host.

Penicillin

Inhibits cell wall synthesis.

Cephalosporin

Inhibits cell wall synthesis.

Polymyxins

Disrupt cell membrane integrity.

Ciprofloxacin

Inhibits DNA replication.

Tetracycline

Inhibits translation at the ribosome.

Sulfonamides

Inhibit folic acid synthesis.

Relenza

Treats influenza (flu).

Acyclovir

Treats herpes.

Harvoni

Treats hepatitis C.

ART (antiretroviral therapy)

Used for herpes.

Remdesivir

Used for COVID-19.

ESKAPE pathogens

Major drug-resistant bacteria: E – Enterococcus, S – Staphylococcus, K – Klebsiella, A – Acinetobacter, P – Pseudomonas, E – Enterobacter

Sepsis-causing bacteria

Escherichia coli, Salmonella, Klebsiella, Pseudomonas, Enterobacter

Organs most prone to drug toxicity

Kidney and Liver

Drug most likely to cause an allergic reaction

Penicillin

Kirby-Bauer test

Determines the most effective antibiotic using disc diffusion.

Therapeutic index

Ratio of drug’s toxic dose to effective dose (higher = safer).

Coliform

Bacteria that ferment lactose; includes Escherichia, Enterobacter, Klebsiella, Serratia (EEKS).

Noncoliform

Bacteria that do not ferment lactose; includes Proteus, Brucella, Legionella, Francisella, Bordetella, Burkholderia (PBLFBB).

Enteric bacteria

Bacteria that live in the intestines; can be coliform or noncoliform.

Pseudomonas aeruginosa

Obligate aerobe.

Brucella abortus/suis

Obligate aerobe.

Bordetella pertussis

Obligate aerobe.

Escherichia coli

Facultative anaerobe; coliform; enteric.

Salmonella typhi

Facultative anaerobe; noncoliform; enteric.

Pseudomonas aeruginosa infections

Infections occur on the skin in healthy individuals; causes chronic pneumonia in cystic fibrosis patients.

Brucella abortus/suis reservoir

Cows and pigs.

Most at risk for Brucella infection

Farmers, slaughterhouse workers, veterinarians.

Fever pattern in brucellosis

Undulant (wave-like) fever.

Disease caused by Brucella

Brucellosis.

Bordetella pertussis disease

Pertussis (whooping cough).

Catarrhal stage of Pertussis

Cold-like respiratory symptoms.

Paroxysmal stage of Pert

Severe, whoop-like coughing fits.

Sepsis

Life-threatening condition caused by an overwhelming immune response.

How do Gram-negative bacilli cause sepsis?

Lipid A release from the outer membrane triggers an aggressive immune response, leading to sepsis.

Pathogenic Escherichia coli

Causes diarrhea.

EHEC (enterohemorrhagic E. coli)

Can lead to hemolytic uremic syndrome.

Salmonella typhi

Causes typhoid fever and diarrhea; transmitted via fecal-oral contamination.

Salmonella enterica

Causes diarrhea; transmitted through contaminated eggs and poultry.

Shigella dysenteriae

Causes diarrhea; transmitted through contaminated water (feces).

Shiga toxin

Produced by Shigella; can lead to hemolytic uremic syndrome.

Yersinia pestis reservoir

Rodents.

Yersinia pestis transmission

Flea bites.

Yersinia pestis diseases

Bubonic plague: swollen lymph nodes. Septicemic plague: gangrene ("Black Death"). Pneumonic plague: infection of the lungs.

Haemophilus influenzae invasive diseases

Meningitis, pneumonia, and sepsis.

Before vaccination, Haemophilus influenzae

Caused meningitis in children.

Haemophilus influenzae vaccine

Hib vaccine.

Normal flora Escherichia coli

Common cause of urinary tract infections (UTIs); particularly in women due to proximity of the urethra to the anus.