First: The doctor spoke about how to study for the exam you should. Returning back to our topic, Gram +ve cocci

Transcription

1 Page1 Few notes before we start : 1. During the lecture, the DR. explained few examples, mentioned some cases, but not within the required material as he said.. Therefore I have not inserted and you can return to the record to listen to them. 2. In fact the Record was not clear in some parts...there are some words from the very, very difficult to hear and write so I did my best and there are some signs ***, words could not be identified and mentioned...forgive me again. 3. It is essential that you return to the slides because there are some parts in slides was not clarified or mentioned by Dr...It is necessary to be studied well from slides First: The doctor spoke about how to study for the exam you should study the lectures given by the doctors if you understand everything this would be enough if you find something incomprehensible you can return to references but you are not required to know all the details, only the major concepts. Returning back to our topic, Gram +ve cocci - We have mentioned that we have two types of staph: 1. S.aures 2. S.epidermidis

2 Page2 - We have also mentioned that S.aures is more important due to its association with the excretion of multi enzymes, and to some extent some strains produce toxins. - One of these important enzymes is called coagulase (refer to the slides for structure). We use serum from animals or human and put it in tube. Then we transfer to it fresh isolated staph and we mix it with the serum and wait for few hours (2-24)... Why? Because some strains produce more coagulase than the others. Thisenzyme enables the conversion of fibrinogen to fibrin, producing clotting that can be easily recognized. - The importance of this enzyme in clinical infections, during infection like skin infection the staph produces an inflammatory reaction producing a clot and this help staph to be covered by this clot and this means to resist the access of blood and the components of immune response that found in blood, in addition to prevent the access of antibiotics all of this leads to be a permanent infection and produce more severe infections therefore sometimes it is necessary to clean the wound and do what called in surgery : surgical drainage, to get rid from damaged tissues. - And this infection has not been discovered to other type of staph and Gram +ve bacteria, so coagulase related infection is one of the characteristics of S.aures. - Always S.aures is coagulase +ve; there is no S.aures which has 1% coagulase ve. - Note: blood is an excellent medium to culture G +ve including Staph. Generally staph grow within 24 hours, so eventually we identify the staphaures in two important tests : 1. Catalase test ( put staph with H2O2 if there are bubbles, this indicate that the H2O2 is broken down to H2O and oxygen by catalase found in the staph) 2. Coagulase test.

3 Page3 3. Instead of coagulase test we can do mannitoltest because most of S.aures sensitive to mannitol but test #2 is still more accurate and more favorable. - First important step we isolate any type of staph whether coagulase +ve or coagulase ve to know if it is sensitive or resistance blood *** oxacillin(the word oxacillin or methicillin are the same, they are similar drugs that have the same action)in the Lab we use oxacillinand we report methicillin. - Methicillin resistant staph as we said is very important in clinical practice because this means that you have to use more advanced types of drugs (by I.V) so it is an important feature to know if staph is b-lactamase resistant and methicillin resistant. - Remember that b-lactamase resistance mean that it resists penicillin in general but methicillin resistance is a more advanced type. - Methicillin resistance is more dangerous; more difficult to treat. - In relation to staph, we have anothercocci called micrococcus. It is coagulase ve staph and is considered as a contaminant ( in skin and urine for ex.). It rarely causes inflammation. It shouldn t be considered as pathogen; it is a contaminant, or an opportunistic pathogen. Second group of cocci: - It is called strep - It is divided into groupsthat can be easily demonstrated by gram stain (majority of the chains of cocci). - This organism, the group of streptococci, is related to secretions of hemolysis. This hemolysis is associated with hemolytic reaction in red blood cells and in red blood cells found in culture media. - So we recognize the hemolytic activity by demonstrating a complete hemolysis. Structure of the RBC and culture media (like blood agar) and this indicate the presence of what we call b-hemolytic streptococci.

4 Page4 - Hemoglob5in of the RBC will be not break down and lose its color but it will be converted to verdo**** which mean you recognize green pigment. - Viridans Streptococci Group: found in oral cavity, and from these group we have certain species associated with oral abscesses, which mean it is part of normal flora but under certain condition it produce inflammation in our gum (you can read in details about it in Wiki or in Green wood book) in association with other pathogens it can also cause teeth caries. - It is considered as protective to our mucosa because it prevents the attachment of other pathogens. - Generally, all population carry viridians streptococci and from it we have many species..(the doc said that he won t give us these species now!!) if a dentist didn t use proper procedures before removing a tooth or another action these cocci may enter the blood stream and reach the heart and cause endocarditis which is a slow progressive disease. (almost 1/3 of all cases of endocarditis is associated with this organism) In relation to Beta-hemolytic Streptococci Group : according the composition of cell wall there is a layer called c carbohydrate layer in the cell wall it is called c- carbohydrate due to the presence of certain types of sugars - According to c-carbohydrate layer, we can divide the Beta-hemolytic Streptococci Groupinto major categories(serogroup) : A;B;C;D;F;G, and within each group we have many subgroups ( up to 80 sometimes).. indicate how much are complicated but that is important.. I expect to pass through life but once. If therefore, there be any kindness I can show, or any good thing I can do to any fellow being, let me do it now, and not defer or neglect it, as I shall not pass this way again.

5 Page5 - The major two important groups are : A and B.. why?? in A and B groups are associated with the majority of clinical topics for example ; group A associated commonly with pharyngitis in young children due to time it takes children to develop an immune response to prevent the attack of Beta-hemolytic Streptococci Group( the doctor said example at to but he said that we don t need to know about it..).. - We might ask why is this organism highly pathogenic? Pathogen is related for two important factors in relation to1.morphological structure and 2.excreation of enzymes. - Group A streptococci produce a variety of extracellular enzymes, we won t mentioned all of them, we will concern only with a few Hemolysinswhich contribute with inflammatory reaction and what is called diffusion of infection - And it produce in relation to bacteriophage what we called Erythrogenictoxin and this toxin is associated with skin infection.. specially in children and this skin infection is called scarlet fever. - And more important, due to 80 specific subtypes of Group A Hemolytic Streptococci, it is not easy to prepare vaccines, because it s not related to one toxin or one antigen etc but for example ; we can diagnose achild suffering from diphtheria because diphtheria causative bacteria produce one type of toxin but in case of Group A Hemolytic Streptococci, it is difficult to produce a vaccine against each serotype (subtype). - Also,Group A Hemolytic Streptococcican be classified by using serotypes. - Now there is a very simple test in the laboratory.to decide whether the bacteria is a group A or not it is very important because group A is repeat infective but protective from the reoccurrenceof group A infection otherwise he will suffer from complications, therefore he must be treated with antimicrobial drugs and he might need one or two years.so it is important to distinguish between group A strep.cocci from other hemolytic

6 Page6 sterp.cocci including the velidince streptococci. A simple test to distinguish them is bacitracin test. Bacitracin antibiotic as you know inhibits group A streptococci were as velidence streptococci and others are resistant. Secondimportant group : Group B streptococci - Similar to previous group but less associated with upper respiratory tract infections and complications. - Can pass to vaginal flora represent % of this flora and can reach to 50% - Usually, originated from group B streptococci from the intestinal tract. Reach the vagina and reside there - This bacteriais present as a part of normal flora under normal condition but the problem in relation to the pregnant if during pregnancy there still aninfection with group B strep.cocci; then any complications during pregnancy or delivery might result in an injury in uterus and this mean that group B strep.cocci might reach the respiratory tract of neonatal baby and result in formation of severe infection. And within short period without antimicrobial drug the infected women die it is very severe and dangerous infection. - And second we have Neonatal meningitis group B can reach the respiratory tract and further can manage to reach blood stream fatal within 24 hours without treatment. - And Group B is associated with urinary tract infections Other groups C,D,G,F : are less important but they also associated with infections like respiratory tract infections but they still are of minor importance and we will not discuss them in details.. Last type of streptococci : streptococci pneumonia : - It is an interesting type of streptococci. It is the causative agent of lung*****infection which is due to the presence of large capsule

7 Page7 inhibiting the immune response and it will not be easily eliminated from the lung. - It is similar to Viridans streptococci produce partial hemolysis ( green pigmentation ),but there is a difference between Viridans streptococci and streptococci pneumonia this difference can be seen in culture plates if you use a Optochindisk : ( chemical used in cell culture techniques for the presumptive identification of Streptococcus pneumoniae, which is optochin-sensitive, from other alpha-hemolytic streptococci such as Streptococcus viridans which are resistant) from wiki but as doctor said - Why streptococcus pneumonia is a major pathogen? 1. There are at least eighty serotype and in each one the type of polysaccharides is different. 2. They produce specific enzymes of group ( hemolysin ) that is similar to enzyme hymolysin protease. - It is found in the upper respiratory tract of the normal person, as a part of normal flora, and any change in normal flora as a consequence of using any antimicrobial drug,these streptococcus pneumonia might increase in number and will take the Opportunity to increase in number and produce more toxin. - Again we say,despite the fact it is found in few numbers but under certain physiological factors or in relation to any inflammatory action in the respiratory tract due to virus for example ( influenza, adenovirus, corona virus,,etc ) so that will enhance activate the presence of the streptococcus pneumonia to increase in number and further to produce infection (like pneumonia ) and even might reach blood stream and result in meningitis especially in groups of patients ( young children and people lacking immunity ) these groups of patient are highly susceptible to develop pneumonia due to streptococcus pneumonia - But we able to produce a vaccine and it is available there are vaccine for children pronounced new-m'cockland for vaccine for adults

8 Page8 This vaccine protect up to 90% of children from pneumonia and make sure to give to all children that suffer from immune deficiency because it is protective especially against meningitis because when streptococcus pneumonia reach blood it produce fatal meningitis in short period so it is important to protect children especially young children against complications of these cocci and especially again we say it is important in young children and children suffer from immune deficiency in addition to adults.. - We have in addition a problem in relation to antimicrobial resistance of streptococcus pneumonia - First :we return back to group A streptococci, this group is highly susceptible to penicillin all group A streptococci anywhere in the world it considered susceptible to penicillin.. - In the other hand, streptococcus pneumonia thirty years ago was up to 95% susceptible to penicillin in the past, it was always considered as susceptible to penicillin.. now, less than 10% in certain countries is considered susceptible to penicillin so as doctor, and you have a child with streptococcus pneumonia and You fear this child will be infected with meningitis and know that streptococcus pneumonia might resist penicillin so you should think with other drugs (cephalosporin for example ) - The last type in relation to streptococci.we have type of organism called Enterococcus, Enterococcus mean in relation to intestine. What s interesting about enterococcus is that it originated from animal flora, intestinal animal flora and with animal human contact it now resides in humans as well. In the past it was in few percentage because as we said before in the intestine we have biological equilibrium, there are organisms that can support the Enterococcus and others prevent the over growth of it. But later in 1970s with introduction of second and third generations of Cephalosporins, here we noticea change in the presence of Enterococcus in intestine it have increased due to the fact that Enterococcus are resistance

9 Page9 to cephalosporins which support the presence of Enterococcus in intestine and Enterococcus become an opportunistic bacteria if it reach another places, it will produce severe infections for example ; in the urinary tract where produce damage, very difficult to eradicate - Also Enterococcus might be associated with wound infection, blood sepsis, and also might be associated with Endocarditis - We have noticed Enterococcus resistance to vancomycin that is very dangerous because it is very difficult to treat a patient without using the vancomycin. But in the other hand, the percent of infection caused by Enterococcus still small but we will recognize it in the future.. - There is no vaccine necessary against Enterococcus the only available vaccine in relation to S.pneumoniae they try to develop a vaccine against Group B but it still experimental work And here we will stop with streptococcus. Third group of gram +ve bacteria called corynebacteria - coryne: means that have many morphological structures. - Are part of normal respiratory tract flora of human and animals, so they usually found in oral cavity and in respiratory tract flora. - According to researches,corynebacteriais an important as protective organism in the respiratory tract, might inhibit the growth of other harmful organisms. - But one of these corynebacteriahas a species of highly important bacteria calledcorynebacteriadiphtheria is highly important, it is causative agent of clinical disease diphtheria. - For your information, diphtheria has not occurred in Jordan since 1981 the last 3 cases discovered was the last cases since that time

10 Page10 due to widespread of vaccines against diphtheria, tetanus, and woben cough - we manage to be protective against diphtheria, because diphtheria is highly infectious agent and in respiratory tract we might recognize both toxic and non- toxic corynebacteriadiphtheriae. - toxicc.diphtheriae in relation to epithelium to presence of bacteriophages which integrated with the chromosomal of bacteria and produce lysogenic and these carry genes responsible for production of exotoxin. - Therefore not all varieties of c.diphtheriae which found in the respiratory tract are considered toxic there are percentages considered as non toxic. And these percentage in relation to protect against harmful bacteria. - So the virulent substance in relation to diphtheria is the production of very specific toxins. These toxins once accumulated during the inflammatory reaction the***** in staph will be disseminated and absorbed in the body and specially in the heart and the liver and produce damage in the heart and liver..and in short period result in the death of patient. - In addition, these toxins highly damaging for mucosa of pharynx and larynx and it produces something called edema accumulation fluid which result in respiratory difficulties.in Arabic this disease known as. "الخانوق " - So, diphtheria is very serious disease and it is one of the most killer diseases of the children in our country and in other countries, and before diphtheria vaccines have been introduced, diphtheria was one of the most serious disease that all people were afraid of it, as we said because there were no vaccines and It was not easy diagnose and treat.

11 Page11 At a certain point, you'll know when, you've reached a time for change, no going back...you've come too far. Don't look down at all things that could go wrong if you fall. You can deal with them when and if they ever even happen. It's your time to use those wings of yours and fly. Done by : Abdulra7man Al 7mouz. Special thanks to : Abdulra7man Azzam.