Friday, November 9, 2007

Ans to synovial fluid

Sorry for the late replying as I need to ask my colleagues.


1.) Blood-stained synovial is hemorrhage. It bleeds into the joint, the blood is usually evenly distributed throughout the fluid. It is caused by traumatic tap. Any time bleeding occurs into the joint fluid, fibrinogen is introduced and will permit clot formation. In the event that fibrinogen is thought to be introduced, a tube containing sodium heparin should be available as part of the collection process. Non-clotted SyF is necessary for the microscopic examination.

2) In normal circumstances, the total protein of synovial fluid will be about 1/3 that of blood plasma. There are a variety of joint disorders that are characterized by elevated total protein levels (examples are rheumatoid and septic arthritis, crystal-induced synovitis, and hemorrhagic problems. It has been found that protein determinations of Synovial fluid does not assist in the differentiating of joint disorders, hence is not reliable. Protein determinations are usually not requested.

Ming Boon:
Traumatic tap is refer to bleeding into the subarachnoid space at the puncture site

For the differentiation of the exudate and transudate fluid is two type of category acording to the Light's criteria. Which i am trying to load the table. The table is the below:


Another limitation will be the fluid cell count must be done immediately as cell will broken down on prolong standing thus fluid must be examine as soon as possible.


Friday, November 2, 2007

Nature and Pathogenesis of Infection

Pathogen: Any organism that is capable of invading the body and cause disease

Parasite: An organism that live in another organism, deriving benefit from it but providing nothing in return.It may or may not be an pathogen. E.g E.histolytica is capable of evading the bowel wall, causing colitis and abcess in liver and other tissue BUT entamoeba. coli live in human gut without causing any disease.

Infection: Refers to a disease caused by a pathogen. It is furtehr defined by the presence of replicating organism in association with tissue damage.

Normal floral may developed into an infection. Usually, it compete with potential pathogen for attachment site by producing anti-microbial substance and compete with nutrient. Under special circumstance, it may become a pathogen, e.g C.difficile altered by antibody therapy produce toxin, causing pseudominate colitis.

Intoxification: It is DIFFERENT from infection, simply mean posioning. E.g adult botulism caused by C.botulinum, develop when food is ingested in which organism has grown and produce a neutraoxin.

Communicable disease: An infection capable of spreading from person to person.
NOTE: Not all disease are communicable.
Transmission may be by direct person to person, respiratory, sexual or mucosal contact and by insect vector.

Pathogenicity: It is the ability to cause disease E.g neisseria gonorrahoae is the causative agent. Some strain have pili while some don't. Those that lack pili are non-pathogenicity. Mechanism of pathogenicty are numerous.

Virulence: It is the power to cause severe disease. It is affected by virulence factors possessed by organism. However virulence may not alway be assoicated with pathogenicity.

Infectiousness: It is the ease which pathogen can spread in a population. E.g measle is highly infectious whereas mump is less so. It can be measure by IRR ( intrinsic reproduction rate).

The behaviour of a pathogen in a population/community depend heavily upon the interaction bewteen the host, agent and enviroment.

1) Host: It affect the chance of explosure to a pathogen and individual response to infection. E.g Travel, sexual behaviour, hygenic, occupation etc

2) Agent factor: It simply refers to the infectiousness, pathogenicity, viruluence and ability to survive in human host and under different enviroment factors. E.g the ability to produce resistance against accine, immune response etc

3) Enviroment factor: Temperature, dust and humidty, use of anitbody and pesticide affect survival of pathogen outside the host.

One case study example:

Host factor affect the transmission of malaria. People who live in endemic area develop partial immunity as a result of repeated explosure. Sickle-cell trail individual has a low rate of parasitaemia as parasite caanot derived effective nutrition from haemglobin.

Agent of p.falciparium malaria has disease resistance to increasing range of prophylactic drug. Ths inevitable mean that traveller now have to search for new vaccine to protect themselves.

Enviroment affect transmission adversely. Malaria diesease predominate in tropical zone especially during rainy season.

Reservoir of infection: It refers to the human/animal population or enviroment in which the pathogen exist and from which it can transmitted.

1) Horizontal spread: It is between individual in the same population E.g Cough

2) Vertical spread: It is from mother to fetal. Many pathogen can cross placenta but few can cause fetal damage.

3) Zoonosis: It is animal disease which is later spread to human.

Outbreak is the occurence of a disease clearly in excess of normal expantancy.

1) Point-source outbreak: Group of individual expose to a single source of infection at a defined point of time. E.g Wedding guest who consumed contaminated food developed food poisoning shortly afterward.

2) Common source outbreak: Group of individual expose to a single source but not at a same time. E.g tattoo palour using contaminated equipment resulting in the spread of Hepatitis B.

3) Person to person outbreak: No common source but maintain by chain of transmission between infected individual. E.g measle outbreak in the school

Hopefully all these information will help you to understand the terminalogy used in M.Mic.

Ching Wei