Gram Positive Bacilli PDF

GRAM POSITIVE BACILLI General Characteristics Many genera (saprophytes, commensals and pathogens) Classified based on:  Cell morphology and arrangement  Atmospheric needs (aerobic/anaerobic)  Catalase production (+/-)  Spore formation (sporing/non-sporing)  Bacillus    Aerobic spore fo...

GRAM POSITIVE BACILLI General Characteristics Many genera (saprophytes, commensals and pathogens) Classified based on:  Cell morphology and arrangement  Atmospheric needs (aerobic/anaerobic)  Catalase production (+/-)  Spore formation (sporing/non-sporing)  Bacillus    Aerobic spore former Habitat: saprophytes, soil , dust, water Species: human infections - B.anthracis - B.cereus - B.subtilis Morphology    Large gram positive bacilli (Streptobacilli) May appear gram variable All species motile ( except B.anthracis) Culture   Most species produce dry beta-hemolytic colonies on blood ( except B.anthracis) B.anthracis : dry irregular colonies non-hemolytic Pathogenicity    B.anthracis: anthrax B.cereus: Food poisoning B.subtilis: infections in immunosupressed Anthrax    Primarily disease of animals Organism in soil, form spore, remain viable for long time Human infected after contact with spores Types of Anthrax  Cutaneous : through damaged skin- can travel to blood (septicemia)  Enteric: Ingestion of contaminated meatfatal  Pulmonary: Inhalation of spores ( Wool sorter's disease) Early Cutaneous Oedema Healing Eschar . Cutaneous Anthrax Infection of the Hand and Cheek Cutaneous anthrax Cutaneous Anthrax       Incubation period:1-7 days Mode of transmission: Contact with spores,spore contaminated materials or infected lesions. Clinical features:Itchy papule like ‘insect bite’ , ulcerates, discharge+, surrounded by swelling. “Painless swelling”: Cardinal Feature D/D Cellulitis. ‘Black Eschar’: Ulcer with depressed black center in 2-6 days. Untreated progresses to Septicemia or meningitis.Case fatality 20% untreated. Responds well to antibiotics. Inhalational anthrax      Chest X-ray: Note Widened mediastinum  Min.Infective dose: 8,00010,000 (US Dept of defense: lethal dose for 50% subjects) Particle size: <5 microns. I.P: 1-7 days. Mild & nonspecific flu like symptoms Second phase: Acute Respiratory distress, sepsis & hemorrhagic mediastinitis causing mediastinal widening. Untreated ~ 97% mortality. Lab diagnosis   Risk group 3 Gram stain: Specimen: large capsulated gram pos bacilli From culture: gram positive, spore , Streptobacilli, no capsule Capsule detection  McFadyean reaction Stain: Loeffler’s Polychrome Methylene Blue stain Result: Organism (blue) Capsule (red) Two plasmids: 1.pX01 2.pX02 Anthrax Weaponization of an innocent bacterium! Biological Agents with potential for misuse & likely Biowarfare routes. Bacterial Viral (all respiratory) Toxins Anthrax ® Argentinian HF Botulinum® Brucellosis Bolivian HF Trichothecene mycotoxins(R,G,D) Cholera (G) Congo-Crimean HF Ricin : Ricinus communis (R,G,P) Meliodiosis® Ebola Staph. Enterotoxin B (R,G) Plague® Hantaviruses Q Fever® Lassa Tularemia® Marburg Rift valley Fever Smallpox Venezuelan Equine Encephalitis Estimated casualties for a hypothetical biological Warfare attack on a city of 500,000: *the model assumes 50kg of agent deployed from aircraft along a 2km line upwind of the city Agent Downwind Reach, km Nos. Dead No. incapacitated Rift valley fever 1 400 35,000 Tick borne Encephalitis 1 9500 35,000 Typhus 5 19,000 85,000 10 500 100,000 Q fever >20 150 125,000 Tularemia >20 30,000 125,000 Anthrax >20 95,000 125,000 Brucellosis Laboratory diagnosis of Anthrax  Specimens: Blood culture,  Sputum, swabs from cutaneous lesions, CSf, dry nasal swab* Environmental: air samples & surface swabs.  Transport with extreme care!  Stains: Gram’s, Spore, Capsular.  Culture on BA/PEA.  PCR, DFA, Strain typing (Ames, Vollum,Sterne) & Serum ELISA for antibodies Bacillus anthracis Vegetative Cells and Spores. A shows a Gram's stain of B. anthracis vegetative bacteria. B shows an electron photomicrograph of a B. anthracis spore (arrowhead) partially surrounded by the pseudopod of a cultured macrophage (x137,000). HANDLING LABORATORY SPECIMEN B. anthracis If B. anthracis is suspected, these precautions should be followed:  Wear gloves and protective gowns when handling clinical specimens & Wash immediately with soap and water if there is direct contact with a clinical or lab specimen- Avoid splashing or creating aerosols  Perform lab tests in an annually certified Class II Biological Safety Cabinet & use standard lab protective eyewear and a mask  Blood cultures should be maintained in a closed system (blood culture bottles)  Keep culture plates covered at all times; minimize exposure when extracting specimens for testing  Work on a smooth surface that can be cleaned easily and wipe with bleach regularly. Lab or clinical specimen material spill or splash:  Remove outer clothing carefully while still in the area and place in a labeled, plastic bag.  Remove rest of clothing in the changing room and place in a labeled, plastic bag  Shower thoroughly with soap and water in the changing room  Inform your supervisor and Infection Control team If exposure to contaminated sharps occurs:  Follow standard reporting procedures for sharps exposures  Thoroughly irrigate site with soap and water and apply a disinfectant solution such as a 0.5% hypochlorite solution. DO NOT SCRUB AREA.  Promptly begin prophylaxis for cutaneous anthrax* DECONTAMINATION  Effective sporicidal decontamination solutions: Commercially-available bleach, 0.5% hypochlorite (a 1:10 dilution of household bleach) Accidental spills of material known or suspected to be contaminated with B. anthracis For contamination involving fresh clinical samples:  Flood with a decontamination solution  Soak five minutes before cleaning up For contamination involving lab samples, such as culture plates or blood cultures, or spills occurring in areas that are below room temperature:  Gently cover spill, then liberally apply decontamination solution  Soak for one hour before cleaning up  Any materials soiled during the clean-up must be autoclaved or incinerated Treatment of Anthrax Inhalation & Ingestion Cutaneous Ciprofloxacin 500mg BD  Doxycycline 100mg BD  Amoxycillin 500mg TDS All for 60 days   Ciprofloxacin 500mgBD for 7 days. Upto 60 days if concurrent inhalational suspected. Vaccines: Pasteur’s---- pX01-/pX02+ heat attenuated:low immunity. Sterne’s ---- pX01+/pX02-: effective in animals. Michigan --- AVA( BioportR), Cell free filtrates (low EF & LF & high PA). - 0.5ml s/c at 0, 2, 4 weeks & 6,12 & 18 months. - For high risk individuals only, not <18 or > 65 yrs or pregnant females. For inhalational: at least 2 doses with ab response after 7 d. Dealing with a suspicious package  Do not open the letter.If the letter has already been opened and powder spills out, do not clean it up.  Keep others away from the area.Double bag the letter; plastic is best (use plastic/rubber gloves and a mask if available).  Immediately wash your hands with soap and water.  Notify your supervisor & Infection Control team.  Evacuate the area & Ensure that all persons who have handled the letter wash their hands.  Make a list of names of all persons who have handled the letter  Place all clothing items worn when in contact with the letter into plastic bags & Keep these bags with you, so that they are available for law enforcement officials.  As soon as possible shower with soap and water