chapter 3: microbiology

microbiology

the branch of biology dedicated to studying microorganisms—tiny living entities invisible to the naked eye—including bacteria, viruses, fungi, protozoa, and algae. These microorganisms are ubiquitous, present in the air we breathe, the water we drink, and the food we consume.

bacteria

classified based on shape (cocci, bacilli, spiral), gram stain characteristics, and genetic features

cocci

spherical or round bacteria

bacilli

rod shaped bacteria

spiral

corkscrew or spiral-shaped bacteria

gram positive bacteria

stain purple or blue indicating thick cell walls rich in peptidoglycan

gram negative bacteria

stain red or pink reflecting thinner peptidoglycan layers and an outer membrane

bacteria survival conditions

warmth with optimal temp begin body tem at 37 C, nourishment, water, alkaline pH, waste elimination, oxygen, light condition (dark environments)

bacteria produces

through binary fission

binary fission

a process where a single cell copies its DNA and splits into two identical daughter cells

facultative bacteria

can adapt to different oxygen levels, while obligate bacteria require specific environments to survive

bacillus and clostridium

can produce endospores

endospores

highly resistant dormant structures that withstand extreme conditions such as heat, desiccation, chemicals, and radiation. crucial in sterilization challenges because they can survive standard sterilization procedures., can remain dormant for years but when environmental conditions become favorable they germinate back into active bacteria potentially casuing infections or contamination

Staphylococcus

gram positive, commonly found on skin and mucous membranes; S. aureus can cause skin infections, pneumonia and bloodstream infection

MRSA

gram positive, poses significant treatment challenges, spreads via direct contact or contaminated objects (fomites)

streptococcus

gram positive, responsible for illnesses such as scarlet fever, strep throat, and pneumonia, different species cause different diseases with some capable of producing toxins

enterococci

gram positive, normal gut flora but can cuase UTI and endocarditis

vancomycin-resistanct enterococci VRE

resistant to many antibiotics

escherichia coli

gram negative, part of normal gut flora but can cause UTI, sepsis, and neonatal meningitis

salmonella

gram negative, causes foodborne illnesses, salmonella typhi cause thypoid fever transmitted via contaminated food or water

psudomonas aeruginosa

gram negative, prevalent in healthcare environments, causes respiratory, urinary and wound infections especially in immunocompromised individuals, resistant to many antibiotics

kiebsiella pneumoniae

gram negative, causes pneumonia, UTI, and septicemia, often resistant to antibiotics

serratia marcescens

gram negative, associated with healthcare-associated infections including UTI and respiratory infections

legionella pneumophila

gram negative, causes legionnaires' disease, a severe pneumonia acquired from inhaling contaminated aerosols, motably from water systems

viruses

much smaller than bacteria and require electron microscopes for visualization. They are obligate intracellular parasites, meaning they need host cells to replicate

ex: AIDS, flu, ebola, zika, rabies, smallpox, poliomyelitis, measels , herpes, hepatitis

protozoa

single-celled organisms classified by their means of locomotion; some cause diseases like malaria, amoebiasis, and trypanosomiasis.

fungi

include yeasts, molds, and mushrooms; can cause opportunistic infections, especially in immunocompromised hosts (e.g., candidiasis, aspergillosis).

prions

infectious proteins causing neurodegenerative diseases, such as CJD

Creutzfeldt-Jakob disease (CJD)

characterized by long incubation periods, nerve cell destruction, and always fatal outcomes.

multi-drug resistant organisms

MRSA, VRE, CRE, strains of salmonella, mycobacterium tuberculosis and E. coli