vis dis exam 4 stool

what does stool include?

bile, mucus, shedded epithelial cells, bacteria, and inorganic salts

when are stool cultures indicated

in patients who have unrelenting diarrhea (especially for more than 7 days), fever, and abdominal bloating - particularly if the patient has been drinking well water, doing a prolonged course of antibiotics, or has traveled outside of the country

when is a fecal examination done

may if the patient complains of GI symptoms, changes in bowel habits, blood, mucous, or pus in the stool

normal fecal parameters

somewhat pliable consistency, usual brown color is from stercobilin, odor is from indole and skatole (formed from bacterial degradation of proteins through fermentation and putrefaction), normal colonic transit time is 24-48 hours, normal consistency is 70% water

physical characteristics of stool

formed, semiformed, diarrhea, scybala (hard small spherical masses), ribbon like (seen with spastic colon or rectal narrowing)

pasty feces (steatorrhea)

noted with increased fats from gallbladder disease - malabsorption syndromes, pancreas, liver, biliary diseases

greasy/buttery feces

noted with cystic fibrosis

mucousal feces

noted with mucous colitis, bloody mucous clinging to a fecal mass is a sign of neoplasm or inflammatory process of the rectum, mucous associated with blood and pus is found in ulcerative colitis, dysentery, diverticulitis

pus in feces is found in what

ulcerative colitis, chronic dysentery, abscesses, fistulas

fecal blood

often is a result of a minor pathology like hemorrhoids - loss of 50-75ml of blood from upper GI tract can result in black tarry stools, lower GI bleeding is usually red in color - FOBT is part of screening for colorectal cancer in patients over 50 - occult blood may be found in many conditions (tumors, ulcers, diverticulitis, polyps) - tumors of the intestine grow into the lumen and are subjected to repeated trauma from the fecal stream and the friable tumor ulcerates and bleeds

testing for occult blood FOBT

guaiac test - testing for occult blood can detect as little as 5ml and further evaluation is needed

normal stool bacteria and fungi

enterococcus, e coli, proteus, staph aureus, candida, bacteroides, clostridium

common pathogenic bacteria and parasites in stool

salmonella, shigella, campylobacter, yersina, ascaris, strongloides, giardia, cryptosporidium

bowel infections usually present as

acute diarrhea, excessive flatus, abdominal discomfort, and fever

immunity

proteins in the blood are made up of albumin and globulin - gamma globulin is one of the many types of globulins - antibodies are made up of gamma globulin proteins

IgG

constitutes ~75% of serum immunoglobulins

IgA

constitutes ~15% of immunoglobulins and is present primarily in respiratory and GI secretions and in saliva and tears and small amounts in blood

IgM

is responsible for the ABO blood grouping and the rheumatoid factor and elevated in many infections

IgE

often mediates allergic response

IgD

rarely is elevated

cell-mediated immunity

inflammatory response begins after nonspecific detection and processing of infectious agents by macrophages - macrophages become activated and interact with T-lymphocytes - phagocytosis and killing of infectious agents ensues

humoral immunity

activated macrophages may present processed infectious agent antigens to specific memory B lymphocytes in the presence of helper T cells transforms into antibody producing plasma cells - typically IgM rises first, then IgG

antigens

substances capable of binding to an antibody (foreign substance) - if the antigen (test) and the antibody (serum) form a reaction, agglutination/clumping will occur

antibody

produced by lymphocytes - is from the patient’s serum

titer

indicates the strength of the antibody, reactive is positive and non-reactive is negative - if titer decreases, the patient is getting better - the higher the titer number, the more virulent the organism is

syphilis

STD caused by spirochete treponema pallidium

primary stage of syphilis

begins 3-4 weeks after infection recognized by a chancre, painless ulcer that will resolve (darkfield examination is diagnostic at this stage - tests for moist genital lesions and specific for T pallidum)

secondary stage of syphilis

now systemic with variable symptoms like fever, malaise, rash, and may have CNS involvement (the immunologic tests are best method for this stage) - typically followed by a latent period lasting years

tertiary stage of syphilis

3-10 years post infection and involves soft granulomatous lesions (gummas) - may be asymptomatic or have CNS involvement (neurosyphilis) leading to insanity and Charcot’s joints - nontreponemal test may be negative in this stage

syphilis screening tests

nontreponemal tests used in patient’s suspected of having syphilis, VDRL (veneral disease research laboratory), RPR (rapid plasma reagin), detect nonspecific antibodies, nontreponemal tests should be confirmed with treponemal tests to help exclude false positives (measles, mono, malaria, TB, pregnancy, leprosy, old age)

syphilis confirmation tests

treponemal tests are used to confirm reactive nontreponemal tests as they are more sensitive (detect specific antibodies to treponema), treponema pallidium immobilization TPI is very specific, microhemagglutination TP is more sensitive, fluorescent treponemal antibody-absorption is the most sensitive

some radiographic features for Charcot’s (foot specifically)

distention, denser bones, debris, dislocation, disorganization, destruction

what happens after a positive treponemal screening result

a nontreponemal test to differentiate between an active infection (reinfection) and one that occurred in the past and was successfully treated - treponemal tests will be positive for life

lyme disease

caused by spirochete borrelia burgorferi - has a period of activity and remission, early and late cutaneous, cardiac, PNS and CNS, articular, and ocular problems - hallmark is a red macule at the site of the deer tick bite with erythema migrans - detection of antibodies is used to show evidence of exposure

symptoms for lyme disease

early ones are fever, headache, fatigue, depression, and erythema migrans/bullseye rash - late ones may involve joints, heart, and CNS

testing protocol for lyme disease

two-tiered - sensitive ELISA test performed first - if positive or equivocal, then more specific Western blot is run - nonspecific with false positives are common (Rheumatoid, lupus, mono, AIDS, chronic nephritis)

streptococcal infections

streptococci are gram positive organisms - one important pathogen is group A beta-hemolytic streptococcus pyogenes which is responsible for rheumatic fever and poststreptococcal glomerulonephritis, pharyngitis - in addition to culture, extracellular products and toxins are important for serology, as the antibodies produced in response to these are measured - throat swabs act as rapid antigen testing

antistreptolysin O titer ASOT

measures antibodies produced against extracellular toxins, increased titer indicates recent or current infection (typically glomerulonephritis, rheumatic fever, bacterial endocarditis, or scarlet fever)

streptolysin O

enzyme that can lyse RBCs and is produced by streptococcal infections - is antigenic, the body produces ASO which is a neutralizing antibody - ASO appears in the serum 1 week to 1 month after the onset of a streptococcal infection - helpful in determining that poststreptococcal disease such as GN was due to previous strep infection

infectious mononucleosis

self limiting systemic disorder lymphoproliferative condition occurring in early childhood and young adults caused by epstein-barr virus (herpes virus family) - spread by contaminated saliva with approximately 95% of the world’s population exposed - once infection occurs, the virus becomes dormant and can reactivate - has an incubation period of about 10-50 days, lasting 1-4 weeks after fully developed

symptoms of infectious mononucleosis

fever, pharyngitis, lymphadenopathy, extreme fatigue and malaise - may see hepatitis and jaundice with hepatosplenomegaly

infectious mononucleosis laboratory diagnosis

accomplished by noting lymphocytosis and atypical lymphocytes in the peripheral blood - monospot (heterophile Ab screening test) - heterophile antibodies are highly specific but lack sensitivity (70-92% sensitive and 96-100% specific) - ~2 weeks after onset, patients have IgM antibodies that react with warm RBCs

serial dilution that is strongly indicative of infectious mononucleosis

1:56

rubella (german measles)

caused by an RNA virus of the togavirus family and is highly contagious and spread through respiratory secretions - usually self limiting with occasional complications but can be devastating to the fetus especially in the first trimester (congenital rubella syndrome which as a range of serious incurable illnesses) - concern is to determine the immune status of the pregnant woman - spontaneous abortion occurs in up to 20% of cases

rubella virus process

incubation is 10-21 days - adults experience low grade fever, malaise, headache and cervical lymphadenopathy, 50% have maculopapular rash - children exhibit transient rash and fever - fetal exposure can produce severe ocular and brain damage, miscarriage, stillbirths

rubella testing

tests detect presence of IgG/IgM antibodies and the person’s immunity to this - positive ELISA test is wanted because that means the mother has previously been exposed and is immune

human immunodeficiency virus

clinical manifestations vary considerably depending on what stage of the disease process the patient is in (early vs late) and the genetic make up of the patient - after the primary infection, there is a relatively asymptomatic period in which significant immune damage is being done particularly to the lymph nodes - patient may progress to a more symptomatic stage leading to classis AIDS

CD4 count

gages how well immune system is working - WBCs that fight infection so the more you have the better, but HIV kills these cells - when the CD4 count drops below 200 due to advanced HIV disease, the person is diagnosed with AIDS - normal range is 600-1500

viral load tests for HIV

measures the amount of HIV is in the bkoow - lower levels are better - helps indicate how rapidly HIV is progressing

first clinical symptoms of HIV patients

night sweats, fever, lymphadenopathy and fatigue followed by extreme weight loss, diarrhea, opportunistic infections and malignancies

new CDC algorithm for HIV testing

screening immunoassay that detects HIV-1 and HIV-2 antigen/antibody combination - second immunoassay that helps differentiate HIV-1 and HIV-2 antibodies - a confirmatory nucleic acid amplification testing (NAT) - this has greater sensitivity for detecting early infection in comparison to the classic testing algorithm - Western blot no longer confirmatory

types of seropositive arthridities

rheumatoid arthritis, systemic lupus erythamatosis, scleroderma, Jaccoud’s arthritis

seronegative spondyloarthropathies

these are RF negative but HLA-B27 positive - ankylosing spondylitis, psoriatic arthritis, reiter’s disease/reactive arthritis, enteropathic arthritis

antinucelar antibodies ANA

a group of antinuclear antibodies used to diagnosis SLE - positive results occur in 05% with SLE, but other rheumatic diseases are associated with ANA - there are several patterns of fluorescence seen through the UV microscope and when combined with the specific ANA subtypes, the pattern becomes more specific for various autoimmune disease - presence detects collagen and autoimmune disorders

rheumatic factor

abnormal IgG antibodies produced by the lymphocytes in the synovial membranes act as antigens, other IgG and IgM antibodies in serum react with synovial antigenic IgG to form immune complexes - these immune complexes react with the complement system and other inflammatory systems to cause joint damage - the reactive IgM is called RF - tissues other than joints like blood vessels, lungs, nerves, and heart may be involved in the autoimmune inflammation - tests for the RF are directed towards the identification of the IgM antibodies - titer must be greater than 1:80 for positive RF - RF does not disappear if patient is in remission

where does RA affect the most

MCPs, PIPs, and wrists - any synovial joint can be involved though

rheumatoid diagnosis

need at least 4 of these - morning stiffness for at least 6 weeks, pain on joint motion for at least 6 weeks, swelling of at least one joint for at least 6 weeks, swelling in at least one other joint for more than 6 weeks, bilateral symmetrical joint swelling, subcutaneous nodules, radiographic changes (marginal erosions, ulnar deviation)

human leukocyte antigen - HLA’s

histocompatability antigens of humans belong to the HLA system and are present on all cells, most easily detected on leukocytes - more than 27 different antigens have been identified, located on chromosome 6 - HLA complex helps immune system distinguish the body’s own proteins from proteins made by foreign invaders - used to identify compability with organ transplants - AS has a +90% positive HLA-B27

ankylosing spondylitis

chronic inflammatory disorder predominantly affecting young adult males and the axial skeleton - characterized by a sequela of articular ankylosis, ligamentous ossification and enthesopathic changes - chronic aching stiffness typically originate in low back especially SI joints - 50% of patients will have peripheral disease especially of the hips and shoulders (spondylitis rhizomelique) - etiology unknown - initial changes consist of synovial proliferation, inflammatory cellular infiltrate producing pannus

clinical features of AS

male 15-25 years old, 3 months of physician observed pain and stiffness, limited spinal motion, sacroiliitis, limited chest expansion, presents as spinal pain and stiffness, iritis and/or conjunctivitis, positive HLA-B27 and ESR and negative RA and ANA, usually no disability, aortic insufficiency, pulmonary fibrosis

AS management

aimed at long-term plan to prevent, decrease, or delay joint and postural deformities, NSAIDs to limit joint inflammation and pain, suggest a rheumatological consultation with any inflammatory joint disease

sacroiliitis

classic initial site of skeletal involvement - hazy loss of subchondral (cortical) definition, erosions and joint space widening - 50% will progress to fusion