Microbiology Lab Exam #4

Total number of people in a population who have a disease at a particular time, regardless of when they caught it or when they were diagnosed

(Total # of cases in the pop/Total # of people in the pop) * 100,000

The number of new cases of disease that occur within a certain time period

(# of new cases in the pop/# of people in the pop) * 100,000

A disease acquired by many in a given area in a short time

Worldwide epidemic

A disease constantly present in a population

A disease that occurs occasionally in a population

• A & A -> A
• A & O -> A
• B & B -> B
• B & O -> B
• A & B -> AB
• O & O -> O

• Rh+ & Rh+ -> Rh+
• Rh+ & Rh- -> Rh+
• Rh- & Rh- -> Rh-

When a Rh- mother is pregnant with an Rh+ baby.  At birth, when the placenta ruptures, the mother's RBC's recognize the baby's blood as foreign creating antibodies against Rh+ blood creating problems with future pregnancies in which the baby has Rh+ blood.

Granulocytes & Agranulocytes - depends on the absence or presence of stained granules in the cell's cytoplasm

Neutrophils - light purplish granules stained up by neutral dyes; primary phagocyte of the blood stream

Basophils - granules attract basic dyes, which stain the granules dark purple; granules contain histamine & other chemicals involved in allergies


Eosinophils - granules stained bright red or orange by eosin; purpose is uncertain but may be to engulf antigen-antibody complexes

Lymphocytes - have a very large nucleus with little cytoplasm around it; B-cells & T-cells that are important in acquired, or specific, immunity


Macrophages (monocytes when not mature) - large WBC's with a kidney shaped or C-shaped nucleus - dendritic cells present antigens to lymphocytes

• Neutrophils - 60-70%
• Lymphocytes - 20-25%
• Monocytes - 1-6%
• Eosinophils - 2-4%
• Basophils - 0.5-1%

Lysosomes - necessary for the digestion of engulfed microorganisms

Eosinophils

Glucan & the community of microorganism attached to it

• AKA Cavities
• Formed when saliva forms a coating on the tooth and bacteria that are attached to it use sucrose to produce fructose & glucan which in turn is fermented to produce lactic acid which can buildup and dissolve the calcium of the tooth

Microbiological method for determining susceptibility to dental caries; measures the amount of acid produced by normal flora microorganism in a medium containing sugar; production of acid causes the color of Snyder agar to change from green to yellow

Based on antibody/antigen reactions; can be direct or indirect

Use a known antibody from the lab to directly identify an unknown antigen (microbe) from the patient

Diagnose disease by an indirect route; rather than taking the actual microbe from the patient, these tests check to see what antibodies the patient is producing - serum from the patient is mixed with an antigen from the lab; if a reaction occurs the patient has the specific antibody for that disease

Non-specific antibodies that will react with other antigens besides the microbe causing the disease

Lab antigens that heterophile antibodies react with

Heterophile antibodies produced by Syphilis patients; cross-reacts with other antigens besides Treponema pallidum

One of the reagin's used in the RPR test for Syphilis patients; when the antibodies attach to the cardiolipin antigens, the particles are clumped together as visible, black aggregates but if the patient does not have antibodies for Syphilis there will be no clumping

• 1.  HIV p24 antigens are manufactured & attached to the bottom of a plastic testing dish.
• 2.  The dish is then washed with the blood sample.  If antibodies for the p24 antigen are present then they attach to the antigens in the dish.  This gives an HIV+ result.  If no antibodies are present & only antigens remain then it's a negative result.
• 3.  The dish is washed with a second marker antibody.
• 4.  The dish is then washed with a dye where the second marker antibody is present, the marker will cause the liquid in the dish to change color indicating a positive result.  If the liquid doesn't change color, then it's a negative result.

A diagnostic test for the presence of a particular antibody in the serum of a patient that involves inactivation of the complement in the serum, addition of measured amounts of the antigen for which the antibody is specific & of foreign complement, & detection of the presence or absence of complement fixation by the addition of a suitable indicator system - compare

Protozoa - single-celled eukaryotic organisms like Amoeba & Paramecium; some found in blood such as Plasmodium (cause of Malaria) and Trypanosoma (cause of African Sleeping Sickness & Chaga's Disease)

Helminths (worms) - Nematodes (roundworms), Cestodes (tapeworms), & Trematodes (flukes); the larval stages can pose a serious medical threat by migrating & encysting in various organs of the body; majority of that infect humans tend to inhabit the intestinal tract and can be diagnosed by searching for eggs in fecal smear

Arthropods

• One celled organisms
• 2 stages in their life cycle = trophozoites (motile, eating stage) & cysts (dormant, resistant stage; not all form cysts)
• Categorized by their means of locomotion = spore formers, flagella, ammoeboid movement (pseudopods)

• Causes Malaria
• Reproduces inside of RBCs in the host
• Transmission typically involves an arthropod vector, typically the bite of an Anopheles mosquito
• Sporozoites can also be transmitted through contaminated blood and rarely through child birth

• Sporozoites (the infective stage) travel to and replicate in liver cells
• Merozoites are then released into the blood and travel to the RBCs where they feed on hemoglobin and reproduce asexually
• The RBCs lyse at regular intervals (every 24 hours) releasing the merozoites into the blood stream - this causes fever
• Some merozoites develop into male or female gametocytes and are ingested by mosquitos during feeding on the host

• Causes Malaria
• Blood samples collected to diagnose Malaria
• Anopheles mosquitos are the method of transmission for Malaria

• Urogenital disease transmitted through sexual contact (#1 STI)
• Both males and females can contract - 70% of people infected but have no symptoms
• Symptoms = itching, burning, and foul green-yellow discharge
• Research has linked it with cervical and prostate cancer

• Uses flagella as its method of movement
• Swabs of the urogenital tract would contain the parasite
• Sexual contact is the most common way to contract

• Leading cause of water born infection
• Parasite infects the small intestine in humans
• Campers drinking unfiltered water are a high risk group
• Multiple flagella found on the end of the organism is the method of movement
• Most common method of detection = cysts/trophozoites in fecal smears (string test) and immunoassay or PCR for subtypes

• "Gut amoeba which dissolves tissue"
• Amoebic dysentery
• Most common in tropical regions of the world
• Small intestines get damaged by this parasite
• Moves by pseudopods
• Transmitted fecally/orally

• Commonly associated with pork and bear
• Larvae encyst within a muscle cell
• Larvae are not killed unless the meat is cooked to the proper temperature
• The cysts enter the digestive system and digestion releases the larva causing intestinal pain; adults mate and produce more larva
• The larva can then travel throughout the body causing damage to multiple types of tissues

• Contaminates include pork, bear meat, other wild game that might eat garbage
• Larva of the helminth migrate to other tissues
• Can be diagnosed through blood test or muscle biopsy (look for encysted larvae)

• Adults live in small intestine
• Female worm lays eggs at night around anal opening
• Main symptom = anal itching but some complain of abdominal pain and trouble sleeping
• Diagnosis = scotch tape test
• Treatment = medication to kill adult worms and good hygiene practices to prevent spread (wash linens, clothes, hands, etc)

• Young children are most commonly infected
• Classic method of diagnosis = scotch tape test
• Advice for infected = after beginning treatment, wash all linens in hot water and ensure treatment of the whole family

• S. mansoni and S. japonicum = mesenteric veins around gut/liver - eggs passed in feces, leads to hepatosplenomegaly
• S. hematobium = bladder - eggs passed in urine, sometimes with blood
• Can lead to stunted growth and trouble learning in children

• This helminth lives in snails when not in humans
• Larvae mature in the portal veins of liver then mate and migrate to veins around the gut or bladder depending on species
• Feces and urine are used to diagnose schistosomiasis

• Pigs and cows ingest eggs from soil
• Larvae encyst in muscle
• Humans infected when eating undercooked meat
• Adults live in small intestine and proglottides containing eggs are passed in feces
• Scolex = head with suckers that attach to wall of small intestine
• Rest of body = proglottids or segments containing male and female sex organs; monoeicious)

• Taenia solium = pork tapeworm
• Taenia saginatus = beef tapeworm
• Food sources that contain tapeworms = pork, beef, and fish
• Suckers and hooks of adult tapeworms typically attach to the small intestinal wall
• Larva can encyst in other parts of the body including the brain and when killed can lead to inflammation (encephalitis)

Agglutination

Neutrophils

Eosinophils

Lymphocytes