lec11.docx

**Faculty of Dental medical** **Lecture : 11** **Gram negative cocci** **Gram Positive bacilli** **[Neisseria]** **General features of neisseria:** - There is two medical important 1. *N. gonorrhoeae* ( Gonococci) 2. *N*. *meningitides* ( Meningococci ) - Gram negative arranges in pai...

**Faculty of Dental medical** **Lecture : 11** **Gram negative cocci** **Gram Positive bacilli** **[Neisseria]** **General features of neisseria:** - There is two medical important 1. *N. gonorrhoeae* ( Gonococci) 2. *N*. *meningitides* ( Meningococci ) - Gram negative arranges in pairs ( Diplococci ) - Aerobic - Oxidase pos (+) - Sugar fermenter  1. ***[N. gonorrhoeae]*** **Morphology :** (Gram negative bacilli, non capsulated , non motile , non spore forming) **Culture :** this type of bacteria has more fastidious bacteria, can not grow in blood agar, grow in chocolate agar, need to 5-10% of CO~2~. **Virulence factor & pathogenesis.** 1. Pilli for attachment 2. Porin protein ( prevent phasome) 3. IgA protease ( IgA an antibody secreted by the immune system but this bacteria break IgA 4. Catalase (+) ( that impaired the immune system) 5. Lipo -- oligosaccharide ( endotoxin) 6. B -- lactamase **Diseases:** - **Gonorrhea in male** ( urethritis , discharge , dysuria) I.P 2-5 days, trans only by sexual contact - **Gonorrhea in female:** 50% of the infected females are asymptomatic, it is in the form of urethritis & cervicitis , and could lead to ectopic pregnancy - **Ophthalmia neonatorum :** in new born and could lead to blindness **Lab diagnosis** i. **Specimen (** urethral discharge , cervix, rectum, ) ii. **Direct smear** ( gram negative cocci) iii. **Cultivation** ( chocolate agar) iv. **Identification** ( oxidase +, glucose fermenter ) **Treatment :** ceftriaxone 2. **N. meningitides** **Morophology & culture** - Gram negative Diplococci - Capsulated - Non motile - Non spore forming - Aerobic - Need to 5-10 CO~2,~ can grow in blood agar and chocolate agar **Virulence factor** 1. Pilli for attachment 2. IgA protease 3. Capsule 4. Lipo -- polysaccharide **Diseases:** i. Meningitis : transmitted by droplets , airborne and cause epidemic cerebrospinal meningitis ( ECM) or goes to blood and infect the layers of meninges and cause meningitis ( stiff neck , headache) ii. Water house friderichsen syndrome : this endotoxin cause adrenal gland failure which may lead to death. **Lab diagnosis** 1. 2. 3. **Cultivation** ( blood agar , chocolate agar) 4. Treatment : combination with ceftriaxone and Ampicillin. **Gram Positive bacilli:** a. **Bacillus b. Clostridium** a. ***[Bacillus ]*** **General features of Bacillius** - There is two medical important 1. **B. anthracis** 2. **B. cerus** - Gram positive bacilli large rectangular - Aerobic - Spore forming - Saprophytic organism 1. **[B. anthracis]** **Morophology**: - Gram positive bacilli large rectangular - Capsulated , with a polypeptides structure - Non motile - Spore forming - Not stain by gram  **Cultivation** - Grow in blood agar and the colonies are not B -- hemolytic - Inverted fire tree in gelatin liquefied **Virulence factor** i. **One antigen type** ii. **Capsule ( antiphagocytosis )** iii. **There is 3 components of toxin ( lethal factor (LF) , Edema factor (EF) , Protective factor (PF) )** The first step is the binding of **PA** to specific cell surface this binding allowing the translocation of the **EF** that activate the adenylate cyclase , this leads to an increase of **c AMP** and this make fluid imbalance( fluid accumulation ) observed in affected tissue , also the binding of **PA** and ,**LT** that cause Necrosis. **Diseases :** 1. **Cutaneous anthrax ( malignant pustule ) :** anthrax spore enters through skin abrasions and lead to necrosis ( black lesion with edema)  2. **Pulmonary anthrax ( wool sorters disease ) :** inhalation of anthrax spore and cause infection in the lung , the bacteria then produce toxin and lead to severe respiratory distress , chest pain , and can lead septic shock & death. 3. **Intestinal anthrax :** by eating infected meat with spore and cause vomiting , abdominal pain , bloody diarrhea. **Lab diagnosis :** 1. **Specimen :** fluid from vesicle , sputum , stool and tokes carefully and clinically then make PCR 2. **Direct smear:** gram positive bacilli 3. **Cultivation:** Nutrient agar at 37c for 24h 4. **Identification :** catalase + , Inverted fire tree in gelatin liquefied **Treatment**: ciprofloxacin , doxycycline , monoclonal ( inhalation anthrax). 2. ***[B. cerus :]*** The name of B. cerus comes from cereal. **Morophology :** - Gram positive bacilli - Non capsulated - Motile - Spore forming **Food poisoning:** there is two types of food poisoning ( Emetic type , Diarrhoeal type ) 1. **Emetic type** :eating a rise contaminated with spore , the symptoms appear after 1-5 h , it is heat stable and self limited. 2. **Diarrhoeal type** : by ingestion meat containing spore , the symptoms appear after 8-24h , it is heat labile and cause water diarrhea b. ***[Clostridium ]*** **General features of Clostridium** - There is 4 importance members : 1. *Cl. Perfringens* 2. *Cl. Tetani* 3. *Cl. Botulinm* 4. *Cl. Difficile* - Grabm positive bacilli - Spore forming ( the spore may live 10 years with the bacteria ) - Grow in cooked meat broth - Anaerobes - The natural habitat is intestine of human & animals , soil - Produce potent Exotoxin 1. ***[Cl. perfringens ]*** - - - - **Culture :** Anaerobes ( aero tolerant) , grow on cooked meat broth at 37c for 24 h and can ferment sugar and produce gas and proteolytic ( black color )due to H~2~S production , we can do a sub culture on blood agar from cooked meat broth and produce a unique double zone of hemolysis colonies at 37c for 3 days. **Virulence factors :** 1. **Spore forming :** the spore could protect the bacteria for many years 2. **Gas production :** bacteria can consume glycogen in the muscles producing gas and acid 3. **Leicthinase ( alpha toxin) :** destruction of ( RBS , leukocyte & platelets ) and cause cell death & necrosis. 4. **Theta toxin :** hemolytic and necrotizing effect 5. **Many enzymes :** such as ( DNase , Hyuronidase , protease , Collagenase ) that make the bacteria able to invasive trough tissues 6. **Enterotoxin :** some strains are able for food poisoning **Diseases :** 1. **Gas gangrene (myonecrosis ) :** a deep wound infection leading to tissue necrosis with a poor prognosis, the pathogeneses path of gas gangrene. a. Wound (lacerated , deep) for anerobic condition b. Wound contaminated with *Cl. Perfringens* c. The bacteria convert from spore into germination form d. *Cl.perfringens* starts to ferment sugar in the tissue ( glycogen ) e. Produce acid & gas f. Spreading infection by enzymes g. Proteolytic clostridia responsible for tissue digest and change in color & bad odour by theta toxin h. Gas gangrene : leads to generalized toxiemia and cause Renal failure and deth.  2. **Food poisoning :** some strains of clostridia are able for enterotoxin leads to Diarrhea , no vomiting , no fever. **Lab diagnosis :** 1. **Specimen :** wound swab 2. **Direct smear:** gram positive large bacilli ( no pus) due to Leicthinase enzyme that breaks the WBC 3. **Cultivation:** on cooked meat broth incubate at 37c for 24h in anaerobic condition and subculture on blood agar at 37c for 24-48 h in 2 plate one in aerobes condition and one for anaerobic condition and on egg yolk agar at 37c for 24-48 4. **Identification :** grow in blood agar with double zone of hemolysis , grow in egg yolk agar that contain Leicthinine so the bacteria break it and produce opaque zones , ferment glucose , lactose , maltose & and sucrose with gas.  **Treatment** : remove necrotic tissue , washing the wound by H~2~O2 ( lack catalase ), pencillin in big doses un combination with metronidazole , amputation **2**. ***[Cl. tetani]*** **Morphology :** - Gram positive bacilli - Capsulated - Motile - Spore forming (the site of spore is terminal , with round shape , and not staining with gram) - Looks like drum -- stick appearancr **Culture :** anaerobic , grow on cooked meat broth ( non saccrolytic & proteolytic ) , sub culture on blood agar at 37c for 24h with B - hemolysis colonies and swarming  ***Cl. Tetani (* tetanus ) pathogenesis path way :** 1. Transmission by nail prick or stab wound contaminated by *Cl.tetani* spore. 2. The spore germinate. 3. After multiply the bacteria produce toxin called Tetanospasmin which is goes into blood and travel to CNS 4. General muscular spasm ( tetanus ) 5. Death occurs due to failure respiration or cardiac faliure **Lab diagnosis:** **Clinical :** history of wound contamination **One of the following signs :** 1. Trismus **2.** Risus sardonicus **3.** Painful muscle contractions a. **Specimen :** exudate **b. Direct smear:** gram positive bacilli **c. Cultivation:** on cooked meat broth incubate at 37c for 24h in anaerobic condition and subculture on blood agar at 37c for 24 h **d. Identification :** B- hemolytic colonies , swarming. **Treatment :** tetanus antitoxin should be given (I.M) to any suspected cases **Prevention :** active immunization (DTP) ( 2, 4, 6,& 18 months )and in school entry **[C. *Cl botulinum*]** **Morphology [: ]** - Gram positive large bacilli - Non capsulated - Motile - Spore forming  **Culture :** anaerobic , grow on cooked meat broth , sub culture on blood agar at 37c for 48h ( B -- hemolytic colonies ) **Virulence factor:** 1. Immunogenic ( A,B, & C) 2. Potent neurotoxin (A) , if 1gm spread in air could kill 1.25million of people so it is highly highly toxic but its heat labile destroy at 100c for 20 min **Pathogenesis path way :** 1. Transmitted by canned food ( performed neurotoxin ) 2. Ingestion of spores then germinate and produce neurotoxin 3. Goes to the blood and cause flaccid paralysis Botulism **Diseases :** i. **The classic type :** ingestion of canned food ( performed neurotoxin ) into blood leads to flaccid paralysis respiratory muscle failure , after ingestion (neurotoxin ) the symptoms are double vision , muscle weakness , drooping eyelids , slurred speech , difficulty swallowing final death due to respiratory failure ii. **Infant botulism :**ingestion of the contaminated honey with spore , the normal flora of infant less than 6 m is insufficient so the spore germinate & toxin production , the symptoms are ( weak cry , poor feeding , constipation , poor muscle tone.  iii. **Wound botulism :**wound contaminated with spore , germinate and producing toxin iv. **Inhalation botulism :** dose not occur naturally used only as biotererrorism **Lab diagnosis :** - Clinical - Detection of toxin by ELISA ( serum , stool or food ) or by PCR - Infant detection in stool by ELISA - Gram positive large bacilli - capsulated - Motile - Spore forming **Culture :** obligate anaerobes grow in Cycloserine Cefoxitin fructose agar ( CCFA) (selective media ), incubated anaerobic at 37c for 48h **Pathogenesis of pseudomembranous colitis :** - By hand contaminated with fecal allowing the *Cl. Difficle* to multiply - Producing 2 type of toxins a. Exotoxin A : its Enterotoxin responsible for activation of adenylate cyclase that cause a diarrhea. b. Exotoxin B : its cytotoxin responsible for damage to the colonic mucosa and leads to pseudomembranous colitis this cause a diarrhea ( pus or mucus in stool) , abdominal cramps , fever. **Lab diagnosis :** - Clinical - Cultivation on ( CCFA ) - Detection of toxin by latex agglutination or by ELISA