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- Paired chromosomes, in nuclear membrane
- histones, organelles, polysaccharide cell walls, divide by mitosis identical chromosomes
one circular chromosome, no histones, no organelles, binary fission, Bacteria: peptidoglycan cell walls, Archaea: pseudomurein cell walls
- Deoxyribonucleic acid
- backbone of the DNA strand is made from alternating phosphate and sugar residues (five-carbon) sugar
- Bases: four bases in DNA; adenine (A), cytosine (C), guanine (G), thymine (T)
- The bases are attached to the sugar/phosphate to form the complete nucleotide
- adenine binds only to thymine and cytosine only binds to guanine
- Ribonucleic acid
- a single-stranded molecule
- contains ribose
cork screw, curved
Gram Positive cell wall
- Lipoteichoic acid links to plasma membrane Wall
- teichoic acid links to peptidoglycan provide rigidity to the cell-wall by attracting magnesium and sodium
- Provide antigenic specificity
Gram negative cell wall
- Thin peptidoglycan
- Outer membrane Lipopolysaccharides,phospholipids, lipoproteins,
- Periplasmic space
- No teichoic acids
- Forms the periplasm between the outer membrane and the plasma membrane
- Periplasm contains hydrolytic enzymes for nutrient breakdown and chemoreceptors for chemotaxis
- Protection from phagocytes, complement, and antibiotics
- Porins (proteins) form channels through membrane for entry and exit of solutes
define enzyme and what it does.
- Biological catalysts
- macromolecules that help accelerate (catalyze) chemical reactions in biological systems Specific for a chemical reaction; not used up in that reaction
- Enzymes are highly specific based on their primary secondary tertiary Some are specific for a single type of protein, others for a structure within a variety of proteins
- The turnover number is generally 1 to 10,000 molecules per second
- Catalysis rates of billions times that of the corresponding non-enzymatic reaction 1 reaction/second=200 days
- Many enzymes require an additional small molecule, known as a cofactor, to aid with catalytic activity; Metals, Small organic molecules: coenzymes, NAD+, NADP+. FAD Apoenzyme An enzyme without its cofactor, inactive
- Holoenzyme: apoenzyme plus cofactor, active
the function of ATP
- Adenosine triphosphate (nucleoside triphosphate)
- Has ribose, adenine, and three phosphate groups
- transports chemical energy within cells for metabolism
What biofilms are and what they do
- Microbial communities
- usually found on solid substrates submerged in or exposed to an aqueous solution
- Form slime or hydrogels
- -Made up of polysaccharides and protein/DNA anchor themselves to surfaces using cell adhesion structures such as pili
- Cell to cell communication allows bacteria to coordinate their activity forming a functional community
- -share nutrients, resist harmful environment
- -May contain more than one type of microorganism
- Resist antimicrobials
- interval between initial infection and onset of symptom-variable
- Time depends on microorganism, virulence, number, host reisistanceInterval between the initial infection and the first appearance of signs and symptoms
- follows period of incubation/ characterized by the appearance of the first mild signs and symptoms
- When you first start feeling lousy
Period of illness
presence of severe symptoms/ the disease is at its height, and all disease signs and symptoms are apparent.
Period of decline
- symptoms subside
- Secondary infection vulnerability
recovery. back to predisease.
- Microbes normally present in and on the human body are called normal microbiota Normal microbiota prevent growth of pathogens
- Normal microbiota produce growth factors, such as folic acid and vitamin K
- Resistance is the ability of the body to ward off disease
- Resistance factors include skin, stomach acid, and antimicrobial chemicals
examples of normal microbiota
- Saliva contains millions of bacteria
- Stomach and small intestine have few because of acid and rapid movement of food through small intestine
- Large intestine has millions of bacteria: facultative anaerobes
- Assist in breakdown of food
What are Opportunistic organisms
- caused by normal microbiota or environmental fungi in a seriously debilitated host
- e.g., AIDS patients, broad spectrum antibiotic treatment, diabetes, leukemia, immunosuppressive
Know what Plasmids are and their function
- Plasmids: exist and replicate separately from the cell’s chromosomal DNA
- Extrachromosomal DNA
- Replicate independently of the chromosomes
- Limited number of genes not required for survival
- Can be transferred to other bacteria
- May code for survival factors under inhospitable conditions
an example of pandemic disease
are proteins produced inside pathogenic bacteria, most commonly gram-positive bacteria, as part of their growth and metabolism. The exotoxins are then secreted into the surrounding medium during log phase. Does not cause fever.
- are the lipid portions of lipopolysaccharides (LPS) that are part of the outer membrane of the cell wall of gram-negative
- The endotoxins are liberated when the bacteria die and the cell wall breaks apart/ lipopolysaccharides (LPS), the lipid A component of the cell wall of gram-negative bacteria/bacterial cell death, antibiotics, and antibodies may cause the release of endotoxins/cause fever (by inducing the release of interleukin-1) and shock (because of the TNF-induced decrease in blood pressure)/allow bacteria to cross the blood-brain barrier
- Contributes greatly to the structural integrity of the bacteria
- Crucial importance to gram-(negative) bacteria whose death results if it is mutated or removed
- Presence of endotoxins in the blood is called endotoxemia
What is meningitis
- Predominately caused by three bacteria Haemophilus influenzae, Neisseria meningitides, Streptococcus pneumoniae Possess a capsule for protection from phagocytosis Enter the cerebrospinal fluid Death occurs rapidly from inflammation and shock
- Caused by endotoxin and gram-positive cell wall fragments
- Diagnosis by Gram stain and latex agglutination of CSF
Haemophilus influenzae Meningitis
- Gram-negative aerobic bacteria, normal throat microbiota
- Capsule antigen type b Prevented by Hib vaccine Occurs mostly in children (6 months to 4 years) Nearly eliminated from the U.S.
- Also called meningococcal meningitis
- Caused by meningitidis Gram-negative, aerobic cocci
- 10% of people are healthy nasopharyngeal carriers Symptoms are caused by endotoxin Death may occur within a few hours; mortality=9-12%
- There are 6 capsular serotypes The geographic distribution and frequency of the serotypes varies
- Vaccines directed against capsules produce a poor immune response by memory B cells Must be repeated 3-5 years
Streptococcus pneumoniae Meningitis
- Also called pneumococcal meningitis
- Caused by pneumoniae (a gram-positive, capsulated diplococcus)
- 70% of people are healthy nasopharyngeal carriers
- Leading cause and most common in children (1 month to 4 years)
- Mortality: 30% in children, 80% in elderly Prevented by vaccination
- Fourth most common cause of meningitis Caused by Listeria monocytogenes
- Gram-negative aerobic rod
- The meningitis affects adults and fetus/newborns differently Adults: most likely to occur in immunocompromised Fetus: causes abortion or stillbirth Newborns: brain damage, death
- L. monocytogenes reproduce in phagocytes Spread phagocyte-to-phagocyte
- Treated by bacteriophages able to kill the bacteria
Diagnosis and treatment of bacterial meningitis
- CSF sample from spinal or lumbar tap
- Gram-stain will identify causative agent Administration of antibiotics may initially worsen the inflammatory response
- Increases the amount of bacterial cell membrane products released through the destruction of bacteria.
- Corticosteroids dampen the immune system's response
What is the blood-brain barrier and its effect on treatment of infections
- Blood–brain barrier- makes it difficult for antibiotics to cross.
- separation of the circulating blood from the brain extracellular fluid in the CNS. occurs along all capillaries and consists of tight junctions that do not exist in normal circulation.
- Endothelial cells restrict the diffusion of microscopic objects (e.g., bacteria) and large or hydrophilic molecules into the cerebrospinal fluid (CSF), while allowing the diffusion of small hydrophobic molecules (O2, CO2, hormones).
- Cells of the barrier actively transport metabolic products such as glucose across the barrier with specific proteins
What is encephalitis
Encephalitis: inflammation of the brain
what is Meningoencephalitits
inflammation of both meninges and brain
Why do antibiotics make an infection worse
- Administration of antibiotics may initially worsen the inflammatory response
- Increases the amount of bacterial cell membrane products released through the destruction of bacteria.
Defenses of the human skin
- Perspiration:Salt inhibits microbes Lysozyme hydrolyzes peptidoglycan Antimicrobial peptides Sebum Fatty acids inhibit some pathogens
- Mucous membranes: Line body cavitiesEpithelial cells are attached to an extracellular matrixCells secrete mucusOften acidic which inhibits microbial growthSome cells have cilia to move organisms out of bodyIn eyes, washed by tears with lysozyme
- Normal Microbiota of the Skin
- Gram-positive, salt-tolerant bacteria, resistant to drying Staphylococci, Micrococci, CorynebacteriumSome are anaerobic and inhabit hair follicles. Others are aerobic and occupy skin surfaces
- Produce acids to maintain skin pH at 3-5
Sebum and the role it plays in acne
The root cause of acne is sebum. Skin cells combine with it and the combination clogs follicles.Hormones are also involved
- Gram-positive cocci, coagulase-positive
- Most pathogenic of the staph
- Make up 20% of bacteria of nasal passages
- Can survive on surfaces for months
- Yellow pigment protects cells from uv and killing by neutrophils
- It has multiple genes which code for virulence factors and survival factors
- Skin infection results in a vigorous inflammatory response attracting phagocytic cells
- Pathogenic aureus has the ability to evade the host response
Gram-positive cocci, coagulase-negative Important opportunistic pathogen Only pathogenic when skin barrier is broken Frequent cause of nosocomial infections Most common source of infections on indwelling medical devices Costs of catheter-related bloodstream infections by epidermidis equal ~$ 2 billion annually
skin diseases from Staphylococcus epidermidis
- scalded skin syndrome: exfoliative toxins cause widespread detachment within the epidermal layer
- Impetigo: caused by Staph exfoliative toxin (proteases)
- Toxic shock syndrome: aureus toxin (super antigen)
Streptococcal Skin Infections
- Streptococcus pyogenes (most important)Group A beta-hemolytic streptococci (GAS)
- The type of hemolysin categorizes the strep into alpha-, beta-, and gamma-(non)hemolytic Streptokinases- dissolve blood clots
examples of Streptococcal Skin Infections
- Scarlet fever
- Rheumatic fever
- Severe streptococcal infections:Necrotizing fasciitis (flesh eating bacteria) Rapidly destroys tissue Mortality is 40%
- Toxic shock syndrome: Strep. pyogenes.Typically presents in patients with pre-existing S. pyogenes skin infections
- Caused by cytokine storm resulting from superantigen toxin release
What bacteria cause intestinal disease and how does diarrhea occur
- one of the leading bacterial causes of diarrhea worldwide dysenteriae is usually the cause of epidemics of dysentery, particularly in refugee camps
- Infection: Endotoxin and Shiga exotoxin
- destruction of the epithelial cells of the intestinal Enterotoxin: protein exotoxin that targets the intestines (pore-forming toxins) Cytotoxic, kill cells by increasing the membrane permeability of the mucosal epithelial cells of the intestinal wall
- Increased permeability leads to chloride leakage into the lumen followed by sodium and water movement.
How does Typhoid fever occur
- Salmonella (enteritis and typhoid fever)
- facultative anaerobes
- Zoonotic: can be transferred between humans and other animals
- bacteria enter the lymphatic system of small intestine, liver, spleen, and bloodstream cause a systemic form of salmonellosis
What Mycobacterium causes what and why they are hard to treat?
Mycobacteria incorporate mycolic acids in cell wall Drugs target the synthesis or incorporation of mycolic acid (Isoniazid)
Varicella-Zoster virus, what is causes after its latent period.
After primary infection, virus enters peripheral nerves and may remain latent in dorsal root ganglia- activation causing shingles
process by which two or more different strains of a virus, or strains of two or more different viruses, infect the same cell simultaneously and replicated RNA from the two strains are mixed. Example bird, human and pig have flu virus. combination of viruses in one cell.
- creates influenza viruses with slightly modified antigens, while antigenic shift generates viruses with entirely novel antigens.
- Slow mutation change of proteins. antibodies don't recognize them anymore.
What causes tooth decay
- Strep mutans gram positive cocci primarily responsible
- Tolerates low pH, metabolizes wide range of carbohydrates
- Synthesizes dextran which help form dental plaque
- Bacteria bind to thin film of proteins from saliva and produce dextran from sucrose
- Also produce lactic acid from sugar fermentation
- Dental plaque= bacteria and dextran
- Lactic acid breaks down enamel
what is infection
- growth of a pathogen in intestines
- Organisms penetrate intestinal mucosa
- Incubation is from 12 hours to 2 weeks
what is intoxication
- ingestion of a preformed toxin
- Symptoms appear quickly after ingestion
- No fever
What is gastroenteritis
- inflammation of stomach and intestinal mucosa- diarrhea, dysentery
- Treatment: oral rehydration therapy
- Campylobacter jejuni:
- Caused by Infection Leading cause of food borne illness in the US
- High optimum growth temperature matches that in poultry (42 degrees C)
- All chicken are contaminated with this
- found in healthy adults Disease occurs as a result of prolonged antibiotic use Predominately a nosocomial disease Responsible for greatest number of deaths from intestinal infections
- Treatment is with antibiotics
Types of virulence factors and the ways bacteria protect themselves
- sensitive to mutations
- develop resistance to antibiotics
- discriminating resistance, genes resistance are spread to other bacterias.
- biofilms- resistance to antibiotics and cleaning.
- thick capsules, hemolysins- kills cells, break down tissue.
- Enterococcus faecium (E)
- Staphylococcus aureus (S)
- Klebsiella pneumoniae (K)
- Acinetobacter baumannii (A)
- Pseudomonas aeruginosa (P)
- Enterobacter Species (E)
why are ESKAPE a major problem
responsible for two-thirds of all healthcare-associated infections
why is ESKAPE so dangerous
- virulence factors such as sensitive to mutations, develop resistance to antibiotics
- discriminating resistance,
- genes resistance are spread to other bacterias.
- only aerobic growth; require O2
- growth on top of tube
- both aerobic and anaerobic growth; greater growth in presence of O2
- growth through out tube but more on top.
- only anaerobic growth; ceases in presence of O2.
- growth on bottom of tube.
- only anaerobic growth; but continues in presence of O2
- growth occurs evenly since O2 does has no effect.
- only aerobic growth; oxygen required in low concentration.
- growth occurs in middle, where a low concentration of O2 has diffused into.