Microbiology Exam 3

types of infectious diseases

acute, chronic, subacute, latent

acute diseases

develop rapidly and run its course quickly

ex. measles and cold

chronic disease

Develops more slowly than an acute disease, is usually less severe, and persists for a long, indeterminate period

ex. tuberculosis

subacute disease

intermediate between an acute and a chronic disease

ex. gingivitis

latent disease

characterized by periods of inactivity either before signs and symptoms appear or between attacks ex. herpes virus

kochs postulates definition

must be satisfied in order to prove that a specific organism is the causative agent of a particular disease

Koch's Postulates, all 4

1. specific causative agent must be observed in every case of a disease
2. agent must be isolated form a diseased host and grown in pure culture
3. agent from pure culture is inoculated into a healthy host, the agent must cause same disease
4. agent must be reisolated from the inoculated, diseases experimental host and ID as being identical to the original causative agent

the disease process factors

1. structures such as pili for adhesion to cells and tissues
2. enzymes that help in evading host defenses
3. protect the organism from host defenses
4. toxins that can directly cause disease

adherence or attachment

critical point in the production of bacterial disease

adhesions

proteins or glycoproteins found on attachment pili (fimbriae) and capsules

colonization

the growth of a microorganism on epithelial surfaces, such as skin or mucous membranes or other host tissues

invasivesness

ability to invade and grow in host tissues

hyaluronidase

enzyme digests hyaluronic acid, a gluelike substance that helps hold the cells of certain tissues together

coagulase

triggers blood plasma clotting, allowing bacteria protection from immune defenses

streptokinase

dissolves blood clots

physical barriers

skin and mucous membranes that protect your body and internal organs from injury and infectious agents. These are made of cells that line body surfaces and secrete chemicals

Human beta defensin-2

on human skin destroys pathogens by poking holes in bacterial membranes

mucosa

covers those tissues and organs of body cavity exposed to exterior

antimicrobial agents

a special group of chemotherapeutic agents used to treat diesases caused by microbes

antibiosis

against life

antibiotic

a chemial substance produced by microbes which has the capacity to inhibit or destroy the growth of bacteria and other microbes

synthetic

agents synthesized in the lab

semi-synthetic

agents made partly by lab synthesis and partly by microorganisms

1910

Paul Ehrlich used Salvarsan to treat syphilis

1935

Gerhard Domagk discovered prontosil, a red dye, inhibits growth of many gram-positive bacteria

1936

ernest fourneau disovered that the sulfanilamide portion contained antimicrobial activity

general properties of antimicrobial agents

selective toxicity, the spectrum of activity, modes of action, side effects and resistance of microorganisms

selective toxicity

the antimicrobial agent must harm the microbes without causing significant damage to the host

toxic dosage level

causes host damage

therapeutic dosage level

successfully eliminates the pathogenic organigism if the level is maintained

spectrum of activity

the range of different microbes against which an antimicrobial agent acts

broad spectrum

agents effective against both gram + and gram - bacteria

narrow spectrum

agentseffective against a small number of microbes

modes of action

inhibition of cell wall synthesis

disruption of cell membrane function

inhibition of protein synthesis

inhibition of nucleic acid synthesis

action as antimetabolites

side effect of rifampin

orange or red urine

inhibition of cell wall synthesis

selectively damages bacterial and fungal cells

b-lactam ring

attaches to the enzymes that cross link peptidoglycans and prevent cell wall synthesis

example of what contains a b-lactam ring

penicillin and cephalosporin

polymyxins

a certain polypeptide antibiotic that acts as detergents and distort bacterial cell membranes, bind to phospholipids in the cell membrane, and effective against gram negative bacteria which contains an outer membrane

inhibition of protein synthesis

* example of selective toxicity
* attack bacterial cells without significantly damaging animal cells

aminoglycoside antibiotics

tetracycline, erythromycin, streptomycin, chloramphenicol

\-bind to bacterial 30 s ribosomal subunit and interfere with the translation of MRNA

inhibitition of nucleic acid synthesis

differences between the enzymes used by bacterial and animal cells to synthesize nucleic acids

\-antibiotics of the rifamycin family bind to a bacterial RNA polymerase and inhibit RNA synthesis

action as anti-metabolites

substances that affect the utilization of metabolites and prevent metabolic reactions -\> enzymes

kinds of side effects

toxicity, allergy, disruption of normal microbiota

acquisition of resistance

microorganisms normally acquire antibiotic resistance by genetic changes


1. natural selection
2. chromosomal mutation
3. extrachromosomal resistance such as R plasmids or R factors

alteration of targets

usually affects bacterial ribosomes

\-the mutation alters the DNA such that the protein produced or target is modified

\-antimicrobial agents can no longer bind to the target

\-resistance to erythromyocin, rifamycin, and anti-metabolites

enzyme development

B-lactamase found in various bacteria and catalyze the breaking of the b-lactam ring in penicillins and cephalosporins

mechanisms of resistance

\-alteration of targets

\-alteration of membrane permeability

\-development `of` enzymes

\-alteration of an enzyme

\-alteration of a metabolic pathway

1930 sulfonamides vs now

found to cure the disease gonorrhea but now there are spectinomycin-resistant strains of gonorrhea

sulfonamide-resistance strains

cure is penicillin

penicillin-resistance strains

spectinomycin is cure

indigenous microflora

organisms that live on or in the body but do not cause disease, and have well established associations with humans

resident microflora

comprise microbes that are always present on or in the human body

transient microflora

microbes that can be present under certain conditions in any of the locations where resident microflora are found

human diseases

caused by infectious agents, structural or functional genetic defects, enviromental factors, or any combination of these

mental diseases

can be caused by a variety of factors (emotional, psychogenic or infection)

immunological diseases

allergies, autoimmune diseases, and immunodeficiencies

neoplastic diseases

involve abnormal cell grwoth that leads to harmless or cancerous tumors

Iatrogenic disease

caused by medical procedures and or treatments

Idiopathic diseases

diseases whose cause is unknown

how viruses cause disease

viruses can replicate only after they have attached to cells and then penetrated specific host cells

cytopathic effect (CPE)

in tissue culture systems, once inside a cell, viruses cause these observable changes

productive viral infection

occurs when viruses enter a cell and produce infectious offspring

abortive viral infection

occurs when viruses enter a cell but are unable to express all their genes to make infectious offspring

latent viral infections

\-characteristic of herpesviruses

\-a weakened immune system allows the virus to multiply

\-ex) shingles

persistent viral infections

involve a continued production of virsues over many months or years.

ex. The hepatitis B vrius infects the liver in such a chronic fashion that there may be no outward signs of an infection but leads to cirrhosis of liver or liver Cancer

how fungi cause disease

most fungal diseases result from fungal spores that are inhaled or enter cells through a cut or wound,

ex. certain fungi produce mycotoxins

how protozoans cause disease

some invade and reproduce in RBCs,

ex. Giardia intestinalis attaches to tissues and ingests cells and tissue fluids

how helminths cause disease

intra and extracellular parasites that inhabit intestines or other body tissues and many release toxic waste products and antigens in their excretions

sign

a characteristic of disease that can be observed by examining the patient

ex. swelling, redness, rashes, coughing, pus, runny nose, vomit

symptom

a characteristic of a disease that can be observed or felt only by the patient

ex. pain, shortness of breath, nausea, sore throat, headache

syndrome

a combination of signs and symptoms that occur together and are indicative of a particular disease or abnormal condition

sequelae

even after recovery, some diseases leave after-effects

acute disease

diesase in which symptoms develop rapidly and that runs its course quickly

local infection

infection confined to a small region of the body

ex. boil or bladder infection

focal infection

infection in a confined region from which pathogens travel to other regions of the body, such as an abscessed tooth or infected sinuses

systemic infection

infection in which the pathogen is spread throughout the body, often by traveling through blood or lymph

septicemia

presence and multiplication of pathogens in blood

bactermia

presence but not multiplication of bacteria in blood

viremia

present but not multiplication of virsues in blood

toxemia

presence of toxins in blodo

incubation period

time between infection and appearance of signs and symptoms

prodromal phase

short period during which nonspecific, often mild, symptoms such as malaise and headache

\-indicating onset of a disease

invasive phase

period during which the individual experiences the typical signs and symptoms of the disease

decline phase

period of illness during which the host defenses and effects of treatment overcome the pathogen

convalescent period

tissues are repaired, healing takes place, and body regains strength and recovers

lymphocytes

specific cells of the bodys immune system

antibody and cellular responses

more effective against succeeding invasions by same pathogen than against initial invasions

chemical barriers

oil and sebum produced by sebaceous galnds that have a low pH that inhibits growth of bacteria. HIgh salt content of sweat inhibits bacteria from growing and acidic pH of sotmach is a dense against intestinal pathogens

ph of HCl

1

lysozyme

present in tears, saliva, and mucus

\-cleaves peptidolglycan linkage in bacterial cell wall

cellular defenses

erythryoctyes, platelets, and leukocytes

Plasma makes up \___% of blood

55

formed elements make up _% of blood

45

macrophages

type of phagocytes that destroy not only microorganisms but also larger particles, aka big eaters

phagocytosis

process in which phagocytes digest and destroy invading microbes and foreign particles

phagocytic cells must

1. find, chemotaxis
2. adhere, adherence
3. ingest, ingestion by endocytosis
4. digest microorganisms, digestion
5. exocytosis

chemotaxis

a nonrandom movement of an organism toward or away from a chemical