Prepared by: EGBII; 8-13-11 GRAM POSITIVE BACILLI DANILO D. DEVEZA JR., M.D. Spore-Forming Gram Positive Bacilli Bacilli species - aerobic Clostridium species – non aerobic Bacillus species A. Bacillus anthracis B. Bacillus cereus Bacilli species • Large aerobic, gram positive rods in chains • Most are saprophylic • Most do not cause disease • Important diseases: Anthrax, Food Poisoning • Spores located in center • Non-motile • “Cut glass” appearance in culture • Use nitrogen & carbon for energy • Spores are resistant to environmental changes, dry heat, certain disinfectants 1. Bacillus anthracis • Anthrax: primarily disease of herbivores • Humans are infected incidentally • Acquired by the entry of spores • Injured skin (cutaneous anthrax) • Mucous membrane (gastrointestinal anthrax) • Inhalation (inhalation anthrax) PATHOLOGY • Spores germinate in tissues at the site of entry • Formation of edema & congestion • Spread via lymphatics • Three Anthrax toxin • Protective antigen (PA) • Edema factor (EF) • Lethal factor (LF) • PA binds to specific cell receptors: entry of EF & LF • EF + PA = edema toxin • LF + PA = lethal toxin (virulence factor) CLINICAL FINDINGS • Humans: 95% (cutaneous), 5% (inhalation) • Cutaneous anthrax • 1-7 days: pruritic rash • Papule → vesicle → necrotic ulcer • Lesion has central black eschar • Edema, lymphangitis, lymphadenopathy • Healing by granulation & leaves a scar • Incubation period: 6 weeks • Inhalation (Wool sorter’s disease) • Hemorrhagic necrosis & edema of mediastinum • Pleural effusion • Sepsis • GI: bowel ulceration • Brain: hemorrhagic menigitis DIAGNOSTICS • Specimem: fluid from local lesion, blood & sputum • Chains of large gram positive rods • Blood agar: non-hemolytic gray to white colonies, with comma shaped outgrowths (Medusa head) TREATMENT • Ciprofloxacin: recommended • Penicillin G, Gentamycin, Streptomycin PREVENTION • Proper disposal of animal carcasses • Decontamination of animal products • Protective handling of potentially infected materials • Active immunization of domestic animals 2. Bacillus cereus • Produce toxins that cause disease • Spores germinate, vegetative cells produce toxins CLINICAL FINDINGS • Emetic type (rice) • Nausea, vomiting, abdominal cramps • Self limiting • Diarrheal type (meat dishes & sauces) • Diarrhea w/ abdominal pain & cramps • Enterotoxin : pre-formed or produced in the intestine • Eye infections • Organisms are introduced by foreign bodies • Local & systemic infections • Endocarditis, meningitis, osteomyelitis • Presence of medical device (IV lines) & IV drugs • Presence of B. cereus in stool is not diagnostic • 10 5 bacteria or more per gram of food is diagnostic • Culture: exhibit motility “swarming” TREATMENT • Drug of choice: vancomycin or clindamycin • Resistant to penicillins & cephalosporins Clostridium Species Clostridium botulinium Clostridium tetani Clostridium perfringens Clostridium difficile Clostridium Species • Large, anaerobic, gram (+), motile rods • Decompose proteins or form toxins or both • Spore is place centrally, sub-terminally or terminally • Produce large raised colonies (C. perfringens) • Small colonies (C. tetani ) • Many produce hemolysis on blood agar (C. perfringens: double zone) • Ferment a variety of sugars • Many digest proteins 1. Clostridium botulinium CHARACTERISTICS • Causes Botulism • Found in soil • Produce toxins: • Type A, B, E, occasionally F: human illness • Among the most toxic substances • Destroyed by heating for 20 mins at 100⁰C PATHOGENESIS • Illness is not infection • INTOXICATION • Toxins acts by blocking the release of acetylcholine at synapses & neuromuscular junctions • FLACCID PARALYSIS CLINICAL FINDINGS • Visual disturbances • Dysphagia • Speech difficulty • Signs of bulbar paralysis • Cause of death: respiratory paralysis or cardiac arrest
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Prepared by: EGBII; 8-13-11
GRAM POSITIVE BACILLI DANILO D. DEVEZA JR., M.D.
Spore-Forming Gram Positive Bacilli Bacilli species - aerobic Clostridium species – non aerobic
Bacillus species
A. Bacillus anthracis B. Bacillus cereus Bacilli species
• Large aerobic, gram positive rods in chains • Most are saprophylic • Most do not cause disease • Important diseases: Anthrax, Food Poisoning • Spores located in center • Non-motile • “Cut glass” appearance in culture • Use nitrogen & carbon for energy • Spores are resistant to environmental changes, dry heat,
certain disinfectants
1. Bacillus anthracis • Anthrax: primarily disease of herbivores • Humans are infected incidentally • Acquired by the entry of spores
• Proper disposal of animal carcasses • Decontamination of animal products • Protective handling of potentially infected materials • Active immunization of domestic animals
2. Bacillus cereus • Produce toxins that cause disease
• Spores germinate, vegetative cells produce toxins
• Diarrheal type (meat dishes & sauces) • Diarrhea w/ abdominal pain & cramps • Enterotoxin : pre-formed or produced in the
intestine • Eye infections
• Organisms are introduced by foreign bodies • Local & systemic infections
• Endocarditis, meningitis, osteomyelitis • Presence of medical device (IV lines) & IV
drugs • Presence of B. cereus in stool is not diagnostic • 10
5 bacteria or more per gram of food is diagnostic
• Culture: exhibit motility “swarming”
TREATMENT
• Drug of choice: vancomycin or clindamycin • Resistant to penicillins & cephalosporins
Clostridium Species
Clostridium botulinium Clostridium tetani Clostridium perfringens Clostridium difficile Clostridium Species
• Large, anaerobic, gram (+), motile rods • Decompose proteins or form toxins or both • Spore is place centrally, sub-terminally or terminally • Produce large raised colonies (C. perfringens) • Small colonies (C. tetani) • Many produce hemolysis on blood agar (C. perfringens:
double zone) • Ferment a variety of sugars • Many digest proteins
1. Clostridium botulinium CHARACTERISTICS
• Causes Botulism • Found in soil • Produce toxins:
• Type A, B, E, occasionally F: human illness • Among the most toxic substances • Destroyed by heating for 20 mins at 100⁰C
PATHOGENESIS
• Illness is not infection • INTOXICATION • Toxins acts by blocking the release of acetylcholine at
• Spores germinate in the tissues: tetanospasmin • A fragment: blocks NT release at inhibitory
synapses • B fragment: mediates binding to neuron and cell
penetration of A fragment • Carried intra-axonally to CNS • Binds to ganglioside receptors • Blocks release of inhibitory mediators (glycine and
GABA) at spinal synapses
• Excitatory neurons are unopposed → extreme muscle spasm
CLINICAL FINDINGS
• Incubation period: 4 – 5 days (up to weeks) • Tonic contraction of voluntary muscles • Spasm first in area of injury, then the muscles of the jaw • External stimuli may precipitate muscle spasm • Death: spasm of respiratory muscles
TETANUS
• Trismus, risus sardonicus, opisthotonus
DIAGNOSIS: Clinical *
TREATMENT
• Hyperimmune human globulin (TIG) to neutralize toxin • + Metronidazole or Penicillin • Spasmolytic drugs (diazepam), debride, delay course
PREVENTION
• DTP, DTaP, Td • TIG • Proper wound care
Wound Management
3. Clostridium perfringens CHARACTERISTICS
• Encapsulated • Non motile • Double hemolysis • Ferment CHO • Reservoir: Soil and human colon • INVASIVE
• Gram positive bacilli, non-branching • Catalase (-), Oxidase (-), Indole (-) • Alpha hemolysis on BA • Produced H2S on TSI (Butt Black)
• Differentiated from L. monocytogenes • Distributed in land & sea animals • Transmitted by direct inoculation • Greatest risk: fishermen, fish handlers, butchers, those in
contact with animal products ERYSIPELOID/ SEA FINGER/ WHALE FINGER
• Icubation Period: 2-7 days • Raised lesion w/ violaceous color • Pain & swelling • No pus
TREATMENT
• Penicillin G
3. Actinomycetes • Aerobic • Large diverse group of gram positive bacteria • Form chains or filaments • Categories:
• Acid fast positive: Mycobacteria • Weakly positive: Nocardia & Rhodococcus • Acid fast negative: Streptomyces
&Actinimadura
4. Nocardia Human infection: N. nova complex
• N. farcinica • N. asteroides type IV • N. brasiliensis
Prepared by: EGBII; 8-13-11
DISTINGUISHING CHARACTERISTICS
• Aerobic • Gram-positive branching rods • Catalase positive • Partially acid-fast • Produce urease • Can digest paraffin
• Inhalation of bacteria
• Not transmitted from person to person • Opportunistic infection
• Corticosteroid treatment, immunosuppression, organ transplantation, AIDS, TB
• Begins with lobar pneumonia • Mimic TB • Granulona & caseation are rare
• Abscess formation: usual pathologic process • Spread to CNS, skin, kidney & eyes
TREATMENT
• Trimethoprim-Sulfamethoxazole • Treatment of choice