immune system
1.1Entry points
In spite of its barriers, pathogens still have several various entry points to the body. The principal points of entry are: wounds, the respiratory system, the digestive system or the genitals.
1.2 The route of transmission
Each pathogen has a way of spreading from one person to another. This is known as its route of transmission. There are four main routes of transmission.


1.3 Protection
Tissue specialized in protection
Skin: covers the exterior of the body.
Mucous: covers the inside internal cavities that interact with the exterior (digestive, respiratory, recproductive system
Secretions specialized in protection: saliva, gastric juices, mucus, and tears.
But sometimes foreign elements still manage to penetrate the body.

We have specialized system that is permanently working to destroy or neutralize the intrusion : the immune system

The immune system defends us from any intrusion that might cross our protective barriers and secretions
It is made up of organs molecules, and some very special cells: white blood cells or leukocytes
White blood cells are produced in the bone marrow. These cells are our defense against foreign elements or infectious agents.
Non-specific response
An immediate response to any type of external attack. It only occurs where the attack is taking place.
1.8 Specific response
It is produced when the non-specific response doesn’t stop the invasive agent. It is a specific attack.
Antigens
Specific response bases itself on the recognition of pathogens . It recognizes aspecific part of the pathogen, its antigen
An antigen is a molecule situated on the exterior of the pathogen .
Antibodies
Antibodies are released by white blood cells in order to detect the antigens of the pathogens
Antibodies fulfill two functions
1. Blocking pathogens and immobilizing them.
2. “Marking” the antigen for destruction by the phagocytes.
Antibiotics
Antibiotics are substances that kill bacteria or impede their reproduction.
Antibiotics don’t work with virus or tumoral processes
Vaccines
Vaccination is the introduction of a weakened or dead pathogenic agent, or specific parts of the pathogen (antigen), with a preventive aim. It produces the immune response of a disease’s first attack without causing a genuine infection.

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4. We recommend a selective approach to aspiration of the hip based on the patient’s probability of periprosthetic joint infection and the results of the erythrocyte sedimentation rate (ESR) AND C-reactive protein (CRP). We recommend that the aspirated fluid be sent for microbiologic culture, synovial fluid white blood cell count and differential. Selection of Patients for Hip Aspiration
Probability of Infection Higher Lower Lower Lower Higher or Lower ESR and CRP Results + + or + − + + or + − ++ +− −− Planned Reoperation Status Planned or not planned Planned Not planned Not planned Planned or not planned Recommended Test Aspiration Aspiration or Frozen Section Aspiration Please see Recommendation 6 No further testing

Key for ESR and CRP results + + = ESR and CRP test results are abnormal + − = either ESR or CRP test result is abnormal − − = ESR and CRP test results are normal

Strength of Recommendation: Strong 5. We suggest a repeat hip aspiration when there is a discrepancy between the probability of periprosthetic joint infection and the initial aspiration culture result. Strength of Recommendation: Moderate 6. In the absence of reliable evidence, it is the opinion of the work group that patients judged to be at lower probability for periprostheic hip infection and without planned reoperation who have abnormal erythrocyte sedimentation rates ORabnormal C-reactive protein levels be re-evaluated within three months. We are unable to recommend specific diagnostic tests at the time of this follow-up. Strength of Recommendation: Consensus 7. In the absence of reliable evidence, it is the opinion of the work group that a repeat knee aspiration be performed when there is a discrepancy between the probability of periprosthetic joint infection and the initial aspiration culture result. Strength of Recommendation: Consensus 8. We suggest patients be off of antibiotics for a minimum of 2 weeks prior to obtaining intra-articular culture. iv
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Strength of Recommendation: Moderate 9. Nuclear imaging (Labeled leukocyte imaging combined with bone or bone marrow imaging, FDG-PET imaging, Gallium imaging, or labeled leukocyte imaging) is an option in patients in whom diagnosis of periprosthetic joint infection has not been established and are not scheduled for reoperation. Strength of Recommendation: Weak 10. We are unable to recommend for or against computed tomography (CT) or magnetic resonance imaging (MRI) as a diagnostic test for periprosthetic joint infection. Strength of Recommendation: Inconclusive 11. We recommend against the use of intraoperative Gram stain to rule out periprosthetic joint infection. Strength of Recommendation: Strong 12. We recommend the use of frozen sections of peri-implant tissues in patients who are undergoing reoperation for whom the diagnosis of periprosthetic joint infection has not been established or excluded. Strength of Recommendation: Strong 13. We recommend that multiple cultures be obtained at the time of reoperation in patients being assessed for periprosthetic joint infection. Strength of Recommendation: Strong 14. We recommend against initiating antibiotic treatment in patients with suspected periprosthetic joint infection until after cultures from thejoint have been obtained. Strength of Recommendation: Strong 15. We suggest that prophylactic preoperative antibiotics not be withheld in patients at lower probability for periprosthetic joint infection and those with an established diagnosis of periprosthetic joint infection who are undergoing reoperation. Strength of Recommendation: Moderate

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Work Group
Craig Della Valle MD, Chair Rush University Medical Center 1611 W Harrison St # 300 Chicago, IL 60612-4861 Javad Parvizi, MD, Vice-Chair Rothman Institute 925 Chestnut St - 5th Fl Philadelphia, PA 19107 Thomas W Bauer, MD PhD Cleveland Clinic Foundation Department of Pathology 9500 Euclid Ave Desk L25 Cleveland, OH 44195 Paul E DiCesare, MD UC Davis Medical Center Department of Orthopaedic Surgery 4860 Y St Ste 3800 Sacramento, CA 95817 Richard Parker Evans, MD University of Arkansas for Medical Sciences Department of Orthopedics 4301 W Markham, #531 Little Rock, AR 72205 John Segreti, MD Rush University Medical Center 600 S Paulina St. Ste 143 Chicago, Il 60612 Mark Spangehl, MD Mayo Clinic 5777 East Mayo Blvd Phoenix, AZ 85054 Guidelines and Technology Oversight Chair: William C. Watters III MD 6624 Fa
· The immune system to remembers the pathogens it has already had a confrontation with
· in the case of a second confrontation, a faster and more powerful response takes place.
Allergies
Sometimes our defenses believe that a harmless element is dangerous, so they trigger a disproportionate and inadequate response against it, called an allergy.
1. The most frequent reactions are those that cause non-specific immunity (reddening, itching, sneezing
2. In other cases the violence of the immune reaction can become dangerous.
BLOOD TRANSFUSION OPTIONS |
TYPE | CAN RECEIVE | CAN DONATE TO |
A | O,A | A,AB |
B | O,B | B,AB |
AB | All | AB |
O | O | all |

Each blood type also has specific antibodies in its plasma. Because of these antibodies, certain blood cannot be mixed.
If type Ablood is mixed with type B blood, the type A antibodies determine that type B blood does not belong there.


1. Check the statements that are true. Rewrite the other statements so that they are true.
True. 1. An antibody attaches to an antigen to make it harmless.
Your body has a complex group of defenses called lymphocytes to fight disease.
TRUE 3. White blood cells sweep up and digest bacteria that get into the body
Sulfuric acid in the stomach kills bacteria that enter your body on the food you eat.
People with AIDS usually die from other diseases because the AIDS virus destroys lymphocytes, leaving the person’s body defenseless.

2. Match the description on the left with the term on the right by writing the correct letter in each blank.
a. antigens
b. mucus
c. lymphocytes
d. antibody
e. AIDS

antibody a disease that destroys the immune system
antigens traps pathogens in respiratory system
lymphocytes proteins and chemicals that are foreign to the body
AIDS substance made in response to an antigen
mucus cells attacked by AIDS virus

3. Fill in the blanks using the words below to explain how the healthy immune system functions.
A germ BACTERIA, VIRUS, etc.) invades the BODY and quickly MULTIPLIES

The healthy IMMUNE system fights back sending WHITE BLOOD CELLS to destroy the invaders.

These cells produce ANTIBODIES which destroy the germs.

Germs that survive the attack can cause ILLNESS

ANTIBIOTICS help to finally destroy all the germs.

NORMAL health is restored