Gram-positive bacteria: clostridia and corynebacteria
Katedra i Zakład Mikrobiologii UM Wrocław Important terms
.lysogenic bacteria .anatoxine -toxoid .active immunization .passive immunization .zoonosis Important terms - lysogenic bacteria
Lysogenic bacteria - bacteria that is infected with a temporate bacteriophage and bacteriophage’s DNA is integrated into the bacteria's chromosome (viral genes are present in the bacterium without causing disruption of the bacterial cell)
Important terms - anatoxine
TOXIN TOXOID
Toxicity Toxicity anatoxine = toxoid - bacterial toxinAntigenicity whose toxicity hasAntigenicity been weakened or suppressed; can be used for safe active immunization
Convertion : - heat Stimule active immunity - chemicals (toxoid vacines) Important terms – active immunization
inactivated/killed pathogen non-virulent or attenuated pathogen Bacterial proteins or polysaccharides (Subunit/conjugate) toxoid active immunization - stimulation with a specific antigen to promote antibody formation in the body. Protection against disease may last several years, in some cases for life Important terms - passive immunization
Passive immunity - providing IgG antibodies to protect against infections (immediate, but short- lived protection) : a) natural passive immunity - maternal antibody (mainly IgG) protect the newborn baby b) acquired passive immunity - process of obtaining serum from immune individuals, andacquired then injecting it to protectnatural a susceptible person. Important terms - zoonosis
zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans as a result of direct or indirect contact with animal population gram positive bacteria
bacilli rods
Clostridium Corynebacterium Bacillus Listeria Erysipelothrix bacilli
(endo)spores germination sporulation Family: Bacillaceae
Genus: Genus: Clostridium Bacillus - strict anaerobes - diversity of anaerobic fermentation - facultative or obligate aerobes - variety of extracellular enzymes - many produce antibiotics (biodegradation & invasive infection)
-Bacillus anthracis - Clostridium tetani -Bacillus cereus - Clostridium botulinum - Clostridium perfringens - Clostidium difficile ANTHRAX
zoonosis disease
capsule causative agent: Bacillus anthracis reservoir: environment, farm animals habitat: GIT of animals Bacillus anthracis complex toxin
LF PA EF main forms of anthrax infection
CUTANEOUS ANTHRAX Transmission: Inoculation inhalation septic shock ingestion INHALATION ANTHRAX (pulmonary anthrax) multiple organ failure
GASTROINTESTINAL ANTHRAX ANTHRAX
therapy: .antibiotics (penicillin, tetracyclines, quinolones) .administered before the onset of lymphatic spread ! prevention: .vaccination of animals (Pasteur 1881) .burning of burial of animals that died of anthrax .possible vaccination for „risk” groups Anthrax is a bioweapon
SYMPTOM FLU ANTHRAX
Sore throat Common Occasional
Runny nose Y N
Fever and chills Y Y
Cough, productive Y N
Cough, dry, unproductive Y Y
Schortness of breath Rare Common
Chest pain rare common Bacillus cereus
Reservoir: environment Habitat: environment Transmission: food-borne, inoculation Bacillus cereus infections
Intravenus Occular infections Catheter (cereolysine) related sepsis GIT
Emetic form Diarrheal form
Heat-stable Heat-labile enterotoxine Proteolysis resistant (meat, vegetables) enterotoxin (Rice)
intoxication toxico infection (gastroenteritis) caused by toxin producing in vivo
Clostridium botulinum neurotoxin lethal dose 0,09 to 0,15 µg intravenously reservoir: environment 0,70 to 0, 90 µg inhaled 70 µg orally botulism Descending paralysis flaccid bilateral cranial neuropathies associated with
symmetric descending weakness
Botulinum muscle paralysis toxin prevent the release of acetylcholine, which stops muscle cells from contracting CLASSIC BOTULISM WOUND BOTULISM INFANT BOTULISM
TOXINE PRODUCED
extrinsically intrinsically incubation period -> from 6 hours to 8 -10 days Inhalational botulism does not occur naturally but would result from breathing in toxin used as a biological weapon
Iatrogenic botulism - occur due to accidental injection into the blood stream of commercial botulinum toxin specific treatment of botulism
• Antitoxin – trivalent horse antiserum (A, B, E) • Antibiotics ( toxicoinfection) • Supportive measures (mechanical ventilation) entry points: Clostridium tetani .cuts and wounds .burns reservoir: environment, animals, human .animal bites habitat: GIT of animals and humans .intravenous drug use .body piercing and tattoos .circumcision
Transmission: inoculation incubation period :4 to 21 days sardonic smile lockjaw opisthotonus
tetanus clinical forms: .generalized .local .neonatal .cephalic
complications of tetanus .bone fractures .aspiration pneumonia .tetanic seizures . death
opisthotonus in tetanus tetanus
Treatment supportive care Prevention: antitoxin vaccination antibiotics Clostridium perfringens
flesh-eating bacterium Reservoir: environment, animals , human Habitat: GIT of animals and humans Transmission: inoculation Pathogenesis
Exogenic infection: Endogenic infection: penetrating wound contaminated after gut rupture, septic abortion with spores (rare) foodborne Clostridium perfringens
After: - gut rupture - septic abortion
Gastrointestinal (GI) SOFT TISSUE INFECTIONS diseases
SEPSIS
MYONECROSIS NECROTIZING toxin produced CELLULITIS ENTERITIS in vivo (GASTROENTERITIS) FASCIITIS Myonecrosis
soft tissue infections with clostidia are typically polymicrobial :
Cl. perfringens (10-48h) Cl. septicum (2-3 days) Cl. histolyticum (3-6 days) Cl. novyi (5-6 days)
Incubation period in gas gangrene: 1-7 days
Clostridium perfringens pathogenesis
EXOTOXINS: Known 12 exotoxins DEGRADATIVE (α,β,γ,δ,ε etc.) ENZYMES ENTEROTOXIN:
- Heat-labile protein toxin α = lecithinase - leading tp loss of fluid and proteins Proteases
Role: Dnases Role: Hyaluronidase
A) MASIVE LYSIS OF: : collagenases endothelial cells, erythrocytes Leukocytes,platelets Pathogenesis in gastroenteritis Role: B) INCREASED VASCULAR PERMEABILITY a) LIQUEFY TISSUE C) HEPATIC TOXITI, b) PROMOTE THE SPREAD MYOCARDIAL DYSFUNCTION OF INFECTION attention !
Microscopic examination of necrotic tissue reveals: gram-positive bacilli in the absence of inflemmatory cells, which is the result of lysis by clostridial toxins Produces Beta toxine responsible for: - intestinal stasis - loss of mucosa with formation of necrotic lesions Produces ENTEROTOXIN
Cl. perfringens type : A B C D E
All produces α exotoxine
Produces the bigest amount of α TOXINE Cl.perfringens Necrotizing enteritis (Pig-bel disease)
- β toxin produced by Cl. perfringens type C
- Toxine can be inactivated by trypsin BUT: Groups of risk: Papua New Guinea inhabitants (sweet patatoes) population with malnutration
- presentation: acute abdominal pain, ulceration of small intestine, bloody diarrhea perforation of the intestinal wall septic shock
Clostridium difficile
Reservoir: environment, human Habitat: GIT of humans Transmission: Food-borne, endogenous
• AAD (Antibiotic- Associated Diarrheas)
• PMC (Pseudomembranous Colitis) Most common antimicrobial drugs associated with C.difficile diarrhea
• Cephalosporins • Ampicillin • Clindamycin Clostridium difficile
Endogenous source: Broad spectrum antibiotics alters the normal enteric flora
Exogenous source: The hospitalized patients are more susceptible to the exogenous aquisition of C. difficile – nosocomial infection
Cl. difficile pathogenesis
Toxin A enterotoxin that causes fluid accumulation stimulates an inflammantory response
Toxin B potent cytotoxin (distrupts protein synthesis)
Treatment
• withdraw / replace antibiotics
• Oral administration of metronidazole or vancomycin
• Avoid: antidiarrheal agents( prevent colonic stasis)
• Volume resuscitation for dehydrated patients
Coryneforms = diphtheroids
- Pleomorphic rods - Form clumps that Natural human look like Chinese characters flora of: - skin - upper respiratory tract - urogenital tract - gastrointestinal tract
strict pathogens: .lysogenic Corynebacterium diphtheriae .Corynebacterium ulcerans (zoonosis)
Diphtheria - Corynebacterium diphtheriae
•incubation period is 2–5 days but occasionally longer
•humans are the only reservoir
•The disease has now reached endemic status (less developed countries with unvaccinated or partially vaccinated citizens )
•Diphtheria is a disease that must be notified immediately DIPHTHERIA
Upper RESPIRATORY tract infection CUTANEOUS diphtheria Diphtheria Toxin is synthesized only by lysogenic bacteria under conditions of iron deficiency.
Diphtheria should be considered:
- In unvaccinated patients with pharyngitis - low grade fever - cervical adenopathy - adherent gray exudate in throat
EXOTOXINE of Corynebacterium diphtheriae
A-B type of toxine A B
A -ctive fragment of toxine B - ind toxine to the receptor & (Inhibits synthesis of human mediates delivery A to its target proteins) Fragment A catalyzes the transfer of ADP-ribose from NAD to the eucaryotic Elongation Factor 2 which inhibits the function of the latter in protein synthesis. Ultimately, inactivation of all of the host cell EF-2 molecules causes death of the cell.
Thic, grayish, adherent excudate = Pseudomembrane Diphtheria
BUT LOCAL SYSTEMIC INFECTION EFFECTS (throat) (heart, peripheral nerves) Treatment of Diphtheria
- neutralization of toxin (horse serum antitoxin)
- eradycation of bacteria ( penicillin, erytromycin)
PREVENTION: immunization with toxoid DTaP triple vaccine (+tetanus toxoid & pertussis antigens) Other coryneforms
Corynebacterium ulcerans can carry diphtheria gene-tox may produce diphtheria infection (transmission can also occur through food vehicles such as milk or other dairy products- zoonosis)
Corynebacterium urealyticum- important pathogen of urinary tract Corynebacterium amycolatum- opportunistic pathogen capable of causing endocarditis and sepsis
Corynebacterium jeikeium –opportunistic pathogen of immunocompromised patients
Listeria monocytogenes
Reservoir: environment, Habitat: environment Transmission: food-borne, vertical Listeria monocytogenes - listeriosis
- capable of growth at 4°C - motylity - facultative intracellular bacteria - virulence factor : listeriolysin O pregnant women: miscarriage, premature delivery, serious infection of the newborn (septicemia, meningitidis)
Immunocompromised patients: generalized infections symptoms of listeriosis include fever, muscle aches, sometimes nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur
Erysipelothrix rhusiopathiae growth: 5–42°C reservoir : animals (zoonosis) In humans - three different diseases: . erysipeloid (focal infection /fingers or hands) . generalized skin infection . sepsis (with endocarditis or without; with or without skin lesions) risk groups: people handling animals and products of origin animals (doctors,veterinary students, etc.)