In the Name of God, Most Gracious, Most Merciful

Transcription

1 In the Name of God, Most Gracious, Most Merciful Last lecture the doctor began discussing Brucella...In this lecture he continued and repeated some information which I ll mention anyway! Brucella : Brucella is associated mainly with animals, humans can acquire infection by direct contact with infected animal meat or ingestion of infected milk and milk products that are not pasteurized, with the latter being the main vehicle of transmission of brucellosis. Zoonosis: is an infectious disease that is transmitted between animals and humans. Brucellosis is a zoonotic disease. Species Of Brucella : There are many species of Brucella, each one infects specific animals. Examples of species detected in Jordan and the Middle East are: 1- Brucella Abortus infect cattels (cause abortion in cows). 2- Brucella Melitensis infect goats and sheep (melitensis refer to Mediterranean, this Brucella was discovered in Malta Island in the Mediterranean Sea). In Jordan, during the last century infection with Brucella was mainly due to unpasteurized milk products especially white cheese, but now Page 1

2 Brucella is well controlled due to vaccination of all types of domestic animals (especially goats and sheep), nevertheless sporadic cases can still be recognized. Brucella penetrates the skin, lungs, or GI tract. Penetration is followed by lymphatic spread, facultative intracellular growth in macrophages, and blood and organ invasion. Clinical Features : 1- Intermittent Fever; the fever peaks in the evening and slowly returns to normal by morning (fever increase and decrease during 24 hours), this is very important in developing sweat in the night. 2- Headaches. 3- Fatigue. 4- Joint and bone pain. 5- GI Symptoms. 6- Sweats. 7- Back Pains. Note: Clinical infection is not easily discovered due to various features of this infection, especially if the patient has received antimicrobial drug for a short period, there will be difficulties in differentiation between it and viral infection for example or malignancy. It s very important to detect Brucella and give the PROPER treatment; any failure in treatment MIGHT result in complications for lifelong which can affect any organ of our body causing localized lesions in liver, spleen, bones,..etc. Complications mainly affect CNS (especially the spinal cord) in the form of chronic form of meningitis. Page 2

3 Note: Failure in treatment occurs in up to 10% of patients due to not receiving enough of antimicrobial drug for the recommended duration of treatment which is at least 4 weeks, 6 weeks is even more favorable. Lab Diagnosis: 1- Diagnosis of active disease is made by culture of the organism from the blood, bone marrow, liver, or CSF specimens. Culture requires between 2-6 weeks to recover the Brucella. Packtech Apparatus: A new equipment which can discover the organism within 3-4 days. 2- If culture didn t reveal the presence of Brucella from a suspected case, perform a test known as Agglutination Test; which detects the presence of specific antibodies against Brucella and looks for rising in the titer (level of antibodies in infected person), the first titer may rise up 1-40 or 1-80, and even up to 20000, depending on the immune response of the body. Agglutination Test: a blood test used to identify unknown antigens; blood with the unknown antigen (bacteria) is mixed with a known antibody and whether or not agglutination occurs helps to identify the antigen. (Wiki) Prevention: 1- Prevention should be directed against animals by vaccinating, if a positive case has been detected by the Brucella Skin Test, infected animal should be isolated. Page 3

4 - Infected animals can be used for consumption, except the liver because it would be infected with the Brucella. 2- Control pasteurization of milk and milk products. Campylobacter jejuni: This organism causes DIAREHHEA and food poisoning (like non-typhoidal salmonella). Features: It s a gram negative bacilli, curved (spiral), longest gram ve bacteria, motile, might be associated with 1 or 2 flagella. *Flagella contribute in: Discovering Story: 1- Motility. Campylobacter was discovered in 1976 by 2- Attachment for accident in London in a British hospital, where vegetation in nature. they noticed an outbreak of diarrhea among children, so they investigated the stool searching for: salmonella, shigella, or any other microorganism that would have resulted in this diarrhea EXCEPT for C.jejuni because: 1- this organism cannot be isolated on simple culture media like those used for detecting salmonella and shigella (salmonella/shigella agar, and helicobacter agar), instead it requires a special medium. 2- it s known to cause enteritis and abortion in animals especially in sheep and cattle, but rarely to cause disease in humans. BUT this time it was indeed C.jejuni! C.jejuni in relation to jejunum, it causes watery diarrhea -that might develop into bloody diarrhea-, as well as inflammation. Page 4

5 It releases Cytotoxins causing necrosis in the intestine, illness is associated with: abdominal pain, nausea, vomiting, and mild diarrhea. Treatment is not required because the patient recover without any antimicrobial drugs. Therefore, this infection is important in certain categories of patients (in children more than adults). Diagnosis: 1- Stool examination. 2- Diagnosis relay on using a special culture media (selective media with antibiotics), that is in special laboratories. 3- Note: Diagnosis of C.jejuni is not usually done in our hospitals due to the fact that there are only few cases that have been discovered...so if the physician suspected this infection he asks for it Helicobacter Pylori: Previously this organism was named Campylobacter pylori, because Helicobacter and Campylobacter have similar morphological structures and cannot be differentiated using special stain but by biochemical test. It was until recently they ve separated the two. This organism is very unique: 1- It s the ONLY organism that can survive in the stomach How is that?! It produces urease enzyme in large amounts which split urea (ammonium chloride) of the stomach and duodenum mucosa into ammonia, HCl, and water. Allowing it to resign and produce Cytotoxins. Once it manages to attach to the lining mucosa and to be covered by a layer of urease, it slowly begins to produce inflammatory reaction damaging the mucosa Gastric and Duodenal Ulceration associated with pain and vomiting. Page 5

6 Note: During taking of food you ll not feel the pain, but after emptying the stomach and clearance of food, you ll feel severe pain resulted from damaging and irritation. 2- Infection is asymptomatic, BUT with aging or under stress condition or using of antiacidic drug or any drug, it becomes activated and can cause gastric ulceration. In 1-3% of cases, this gastric ulceration may end with developing cancer or lymphoma. Diagnosis: 1- Recovering of this organism is not easy and requires a special culture media under temperature of C, and the presence of 90% CO2 mixed with 10% nitrogen gas. 2- Urea Breath Test; measures the presence of urea in the stomach. If +ve, there s an infection Children up to the age of 12 years, acquire asymptomatic infection, with aging infection increase >> 50% of adults above 50 have acquired infection. If not, physician takes biobsy from the stomach and sends it to a pathologist to recover it Serological test is not recommended in case of Helicobacter and Campylobacter bacteria because they RARELY invade mucosa and reach blood stream and cause sepsis > usually they cause asymptomatic infection that is associated with low levels of antibodies against them! MycoBacteria: This group of organisms is related to respiratory tract and pulmonary infection. Remember Examples of bacteria which produce sore throat, meningitis, and pneumonia: group A streptococci, haemophilus influnzae, Neisseria meningitides, and Corynebacterium diphtheria. Page 6

7 It s a special group in relation to morphology, culture, and clinical features. (Myco) originated from the Greek word which means ROOT. Why is it called MycoBacteria? ** This organism usually produces filament in culture in vitro giving an impression that is related to Fungi, and in the past they studied the Mycobacterium as part of the Mycology (fungal diseases), but later they separated this organism due to the fact that the morphological structure and the composition of the cell are related to bacteria more than fungi. MycoBacteria is Acid-fast bacilli: It has a special cell wall which is composed of high amount of phospholipids (waxy materials) that cover the cell body of MycoBacteria, and this cell wall contains important chemical structures called Mycolic acid which is a long chain of phospholipids, this high lipid content makes them resist the acidity (acid-fast). Therefore, they can survive in the environment for a long period. For example, acid fast bacilli in sputum (if the person is infected with these bacilli) may persist in the environment and these bacteria survive for years (if there is no sunlight because U.V can kill the bacteria rapidly). Dryness and wetness contribute for surviving the Acid-fast bacilli. If we use gram stain with MycoBacteria, it will not be discolored, which means, the acidity cannot penetrate the cell wall and change the color of Acidfast bacilli (it resists the acidity). Remember in gram stain we use two types of dyes (crystal violet) and later we use iodine to fix the blue color and we discolor with Alcohol.So that, gram negative bacteria will be discolored and gram positive will retain the blue dye. Page 7

8 Therefore we use a special stain called Zeihl neelsen stain which shows the morphological structure of the MycoBacteria. MycoBacteria are small very thin bacilli and usually recognized in clusters or bundles of bacilli (5-6 together), red in color, and not easily recognized (needs experience) because they might be confused with other organisms. Infection: MycoBacteria which infect animals are called MycoBacteria bovis, whereas MycoBacteria which infect humans are called MycoBacteria Tuberculosis (Var humans). It is not easy to develop the features of tuberculosis (lung or pulmonary) in the humans. For example, children usually are exposed to Acid-fast bacilli through the environment or close contact with a person carrying this organism in his respiratory tract. In our country the majority of the population has already acquired bacilli during their life, and this has been proved by using "tuberculin test". Tuberculin Test is a skin test which measures the infection of tuberculosis.any positive tuberculin test means that the person is susceptible, but a negative test means that the person has acquired infection because the neutralizing antibodies usually suppress the tuberculin reaction. The infection usually occurs in the apical areas of the lung. It reactivates in the upper lobe because oxygen tension is the highest there, due to decreased pulmonary circulation, and Mycobacterium tuberculosis is an aerobic bacterium. Interaction between our host tissue and MycoBacteria occurs which results later in developing of "Granuloma lesion" (this means that cells of the tissue have reacted against cells of MycoBacteria and results in developing of lesions but dormant silent lesions, which means, Page 8

9 that the organism will not spread to other parts of the lung or to other parts of the body). This means -in short- that you have already acquired infection and this infection did not result in clinical infection. Therefore, infection with Mycobacterium Tuberculosis is of two types: 1- Primary Tuberculosis; children and young develop this type. Also called "pulmonary tuberculosis exudative type". 2- Secondary Tuberculosis; that is, active productive type of tuberculosis which means that granulomatous regions will be activated (the organism begins to spread to other parts of the lung producing the features of pulmonary tuberculosis). This type is associated with certain clinical features such as: weight loss, general weakness, productive cough (the cough Note: Active productive tuberculosis means that you have a case of infectious patient who might easily infect the others. Whereas the oxidative type (the primary tuberculosis) means asymptomatic person not necessary to split the organism from the sputum or spread the infection. contain large amount of pus cells, epithelial cells and few number of cells!!!) Lab Diagnosis: 1- Direct acid-fast stain (AFS): also known as Ziehl Neelsenstain, is a special stain used to identify acid-fast organisms, mainly MycoBacteria. 2- Culturing of MycoBacteria: The most important clinical specimen in the diagnosis of Mycobacterium Tuberculosis is Sputum; that s because -as Page 9

10 mentioned above- 95% of Tuberculosis cases are Pulmonary Tuberculosis. Sputum must be first treated before the culturing process to get rid of any other organisms. Treatment methods are numerous, and include Alkaline treatment methods (e.g. by Sodium Hydroxide). The other 5% of cases could be: Urinary infection (in which urine is collected over 1-3 days & cultured). CNS infection: in which Tuberculosis causes a subacute meningitis (especially in children), in this case CSF (Cerebrospinal Fluid) is cultured. GI tract infection: in which the biopsy is taken after surgical treatment. Bones infection. Löwenstein Jensen medium: It is a special growth medium to culture Mycobacteria. It is composed of many substrates such as Malachite Green (which inhibits the growth of other types of bacteria), & egg yolk (it is coagulated eggs according to Wikipedia). This medium must be incubated for a significant length of time (3-6 weeks); due to the slow doubling time (generation time) of Mycobacterium Tuberculosis (1-3 hours), compared to other bacteria (20-25 minutes). Treatment: - In Jordan, Tuberculosis is often treated by a combination of 2 or 3 anti-tuberculosis drugs. These drugs include Rifampicin, Streptomycin, INH (Isoniazid), etc Page 10

11 - But recently, Resistance to some of these drugs has been developed. - Normal treatment of a non-resistant Mycobacterium Tuberculosis can be done in 3-6 months and costs only JDs. However, Resistance to one or two of the common anti-tuberculosis drugs may prolong the duration to 1-2 years and may increase the cost to JDs or even more. - BCG (Bacillus Calmette Guérin) vaccines a special vaccine against Tuberculosis, which is effective in more than 50% of the population. NOTE: Detection of positive Tuberculosis cases by x-ray scan of the lungs is more important than vaccination of children. This scan was obligatory to all students in Jordan in the past, but has been stopped due to the low incidence of Tuberculosis in Jordan (only 1 positive case per scans). However, in the last years there has been an increase in the incidence of Tuberculosis, mainly due to expats. Good Luck All Your Colleague: Sara Al-Attal. Special Thanks to everyone who have helped me Page 11