Gram-positive bacilli and rodsGram-positive bacilli and rods ... Gram-positive Rods Corynebacteria...
Transcript of Gram-positive bacilli and rodsGram-positive bacilli and rods ... Gram-positive Rods Corynebacteria...
Gram-positive bacilli and rods
Katedra i Zaklad Mikrobiologii
UM Wrocław
lysogenic bacteria anatoxine -toxoid active immunization passive immunization zoonosis
Important terms
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)
TOXIN
Toxicity Antigenicity
TOXOID
Toxicity Antigenicity
Convertion : - heat - chemicals
Stimule active immunity
(toxoid vacines)
Important terms - anatoxine
anatoxine = toxoid - bacterial toxin whose toxicity has been weakened or suppressed; can be used for safe active immunization
Bacterial proteins or polysaccharides (Subunit/conjugate)
toxoid
non-virulent or attenuated pathogen
inactivated/killed pathogen 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 – active immunization
Important terms - passive immunization
natural acquired
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, and then injecting it to protect a susceptible person.
zoonosis is any disease or infection that is naturally transmissible from vertebrate animals to humans as a result of direct or indirect contactwith animal population
Important terms - zoonosis
Gram-positive Rods
Corynebacteria Listeria Erysipelothrix do not produce spores
Bacillus & Clostridium (spore forming bacteria)
Not closely related
No cause similar clinical conditions
Family: Bacillaceae
Genus: Bacillus
Genus: Clostridium
- product endoepores - facultative or obligate aerobes - many produce antibiotics
- Product endoepores - strict anaerobes - diversity of anaerobic fermentation - Wide variety of extracellular enzymes (biodegradation & invasive infection)
- B. anthracis - B. cereus - B. cereus
- Cl. tetani - Cl. botulinum - Cl. perfringens - Cl. difficile
Bacillus anthracis
• Protein capsule (poly-D-glutamic acid)
• Form spores
• Three toxin protein components (plasmid-coded )
Bioterrorism agent !!!
individulal proteins important in pathogenesis of antrax
• Protective antigen (PA) mediates cell entry of EF &LF
• Edema factor (EF) severe edema (IL-4;disable immune response )
• Lethal factor (LF) tissue necrosis
(TNF-α, IL1-β; kill the cell)
Lethal toxin Subunit A = rapid cell deth by cleaves critical intracellular signaling module
Edema toxin Subunit A = catalyzes production of cyclic AMP within host cell -> dramatic tissue edema
Protective antigen Subunit B = binds toxin to host cells and mediates it internalization)
Bacillus anthracis A-B toxines 2 A-B toxines, which share the same B component
Anthrax
• zoonosis disease
• Is not spread from person to person
How is anthrax spread?
Getting spores in a cut or broken skin
Breathing in spores
Eating contaminated meat
CUTANEOUS ANTHRAX
INHALATION ANTHRAX
INTESTINAL ANTHRAX
Cutaneous Anthrax Symptoms
• Develope 1-12 days
• Begins like an insect bite
• Becomes a fluid- filled blister
• Center turns black and becomes sunken
Inhalation Anthrax Symptoms
• Incubation time: 1-5 days
• Flu-like symptoms
• Fever/ chills
• Muscle aches
• Malaise
• Shortness of breath
Flu symptoms vs Anthrax symptoms
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
Intestinal Anthrax Symptoms
• Nusea, loss of appetite
• Vomiting
• Fever
• diarrhea
Anthrax Therapy:
– penicillin, tetracyclines, quinolones
– administered before the onset of lymphatic spread!
Prevention:
– possible vaccination for „risk” groups
– vaccination of animals (Pasteur 1881)
– burning of burial of animals that died of anthrax
Bacillus cereus infections
GASTROENTERITIS
Emetic form Diarrheal form
Heat-stable Proteolysis resistant enterotoxin (Rice)
Heat-labile enterotoxine (meat, vegetables)
Occular infections (necrotic toxine, cereolysine, phospholipase C)
Intravenus Catheter related sepsis
intoxication infection caused by toxin producing in vivo
Clostridium botulinum
the bacillus of
botulism
• Found worldwide in soil and aquatic sediments
• Botulus (Latin) = sausage
• 15 min, 100°C – destroying of C.botulinum and its toxin
• 121°C, 15 min (moist heat) – spores destruction
CLASSIC BOTULISM
Vegetables, fish contaminated
with spores
Improper process of
food
Spores germination
Bacill multiplying
Excrete toxin into the food
Food is ingested
Toxin absorbtion
Toxine signs appear within 24h – 48h
Appropriate conditions: - Strictly anaerobic
environment - Neutral or alkaline pH
Botulism
failure of neurotransmission flaccid paralysis
Botulinum toxin acts at the neuromuscular junction to prevent release
of acetylcholine, a neurotransmitter that stimulates muscle contraction
Manifestations
of
food-borne botulism
• Very slight gastrointestinal symptoms
• No fever, no sign of sepsis
• Normal mental status
• Descending flaccid paralysis with bulbar signs
„4 Ds” –signs of botulinism
1. Diplopia (double vision)
2. Dysarthria (difficulty forming words)
3. Dysphonia (difficulty intoning words)
4. Dysphagia (difficulty swallowing)
WOUND BOTULISM
• Rare form of botulism
• Wound becomes contamined with the organism, and toxin is absorbed from that site
INFANT BOTULISM „ floppy baby syndrome”
Early signs:
- Constipation
- Feeding problems
- lethargy
- Poor muscle tone
Not only C.botulinum….. C. baratti, C.butyricum
Botulism
CLASSIC BOTULISM (intoxication)
INFANT BOTULISM (infection caused by toxin producing in vivo)
WOUND BOTULISM -toxin producing in vivo in the wound; - symptoms similar to those of foodborne infection - incubation period is longer_
Treatment
• Antitoxin – trivalent horse antiserum (A, B, E)
• Antibiotics ( infant and wound botulism)
• Supportive measures (mechanical ventilation)
Botulinum toxin
and bioterrorism
Lethal dose of toxin for a 70-kg human:
- 0,09 to 0,15 µg intravenously
- 0,70 to 0, 90 µg inhaled
- 70 µg orally
By contaminating food (unlikely)
By inhalation (presence in aerosols)
Medical uses of botulinal toxin
• Dystonia
• Strabismus
• Hyperhydrosis
Other: migraine headaches, achalasia, cerebral palsy
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
Clostridium tetani
• Normal inhabitants of the herbivores
• Produces a round terminal spore („drumstik”)
• Do not invade but remain at the side of infection
Clostridium tetani
• Tetanolysin – hemolytic toxin
• Tetanospasmin – neurotropic A-B toxin
A – responsible for toxic effect
B – binding subunit
Tetanospasmin
- Heat-labile, plasmid encoded
– Produced during stationary phase of growth
– Released when the cell is lysed
– It is destroyed by:
- heating (65°C, 5min)
- action of acid
- proteolytic enzymes
Tetanospasmin
- Being internalized & moves from the peripheral nerve
terminals to the central nervous system by retrograde
axonal transport
– Being released from the postsynaptic dendrites
– Localized within vesicles in the presynaptic nerve terminals
– Acts by blocking the release of inhibitory neurotransmitters (GABA)
– Causing exitatory synaptic activity to be unregulated
Tetanus
Predisposing factor for tetanus:
- area of low oxidation-reduction potential
(necrosis, large splinter)
- coinfection with aerobic organisms
- others:unskilled abortion, scarification rituals,
female circumcision
Tetanus
- generalized - localized - cephalic - neonatal
Tetanus
Incubation period: 4 days- several weeks
• Tingling sensation in the vicinity of the wound
• Muscular spasms
• „ lockjaw”
• Risus sardonicus -„sardonic grin”
• opisthotonus
Treatment
• Surgical management
• Tetanus toxoid – active immunisation
• Passive immunisation with antitoxin
• Critical care unit
•Laryngospasms •Fractures •Hypertension •Nosocomial infections •Pulmonary embolism •Aspiration pneumonia •Death
Complications of Tetanus
Clostridium perfringens
• Part of normal flora (vagina, GI)
• Ubiquitous in nature
• Cl. perfringens strains are grouped A through E type
Pathogenesis
Exogenic infection: penetrating wound, contaminated with spores
Endogenic infection: after gut rupture, septic abortion (rare)
Clostridium perfringens
SOFT TISSUE INFECTIONS
GASTROENTERITIS
CELLULITIS
FASCIITIS
MYONECROSIS FOOD POISONING
NECROTIZING ENTERITIS
SEPSIS
Remember, sometimes just colonization
After: - gut rupture - septic abortion
SOFT TISSUE INFECTIONS
CELLULITIS FASCIITIS = suppurative myositis results from cellulitis Accumulation of pus in the muscle planes no necrosis no sistemic symptoms
MYONECROSIS = gas gangrene systemic spraed necrosiss of muscle painful gas formation
edema erythema gas formation in tissue generally nonpeinful
LOCALIZED ! SYSTEMIC ! -> shock, renal failure
Clostridial cellulitis
• No systemic toxemia
• Infected tissue looks similar to gas gangrene due to gas bubbles fermentation
Myonecrosis (gas gangrene)
Is marked by:
high fever
intense pain
brownish pus
gas bubbles
(CO2, H2S, CH4)
skin decoloration
foul odor
Clostridium perfringens soft tissue infections
- Typically polymicrobic: 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 (α,β,γ,δ,ε etc.)
toxin α = lecithinase A) MASIVE LYSIS OF: : endothelial cells, erythrocytes Leukocytes,platelets B) INCREASED VASCULAR PERMEABILITY C) HEPATIC TOXITI, MYOCARDIAL DYSFUNCTION
ENTEROTOXIN:
- Heat-labile protein - leading tp loss of fluid and
proteins
Role:
Pathogenesis IN
FOOD POISONING
DEGRADATIVE ENZYMES
Proteases
Dnases
Hyaluronidase
collagenases
a) LIQUEFY TISSUE b) PROMOTE THE SPREAD OF INFECTION
Role:
Role:
attention !
Microscopic examination of necrotic tissue reveals: gram-positive
rods in the, which is the result of lysis by clostridial toxins
Cl. perfringens type : A B C D E
All produces α exotoxine
Produces ENTEROTOXIN (food poisoning)
Produces the bigest amount of α TOXINE
Produces Beta toxine responsible for: - intestinal stasis - loss of mucosa with formation of necrotic lesions
Clostridium perfringens human infections
SOFT TISSU INFECTIONS FOOD POISONING PRIMARY SEPTICEMIA
Cl. perfringens type A
NECROTIZING ENTERITIS
Cl. perfringens type C
C.Perfringens Food-Borne Disease
-Intoxication - abdominal cramps, watery diarrhea
- no vomiting, no fever -occurs 8-18h after eating contaminated food (meet products)
- lasts 24-48h
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
Treatment – Surgical debriment
– Very high dose penicillin
– Supportive therapy (HBOT)
Prevention: Cleaning and watching wounds for signs of infection
Clostridium difficile
• 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
weak cytotoxin
Toxin B
potent cytotoxin (distrupts protein synthesis)
Resistant gene casettes (ermB MLS)
Diagnosis AAD
Presence of diarrhea associated with antibiotic therapy in the preceding 4-6 weeks
&
recovery of Cl.difficile organism and/or toxin from the stool
PMC
demonstration of pseudomembranes by colanoscopy & recovery of Cl.difficile from stool
Treatment
• Oral administration of metronidazole or vancomycin
• Avoid: antidiarrheal agents( prevent colonic stasis)
• Volume resuscitation for dehydrated patients
Coryneforms = diphtheroids
Natural human flora of:
- skin - upper respiratory tract - urogenital tract - gastrointestinal tract
Can function as
opportunistic pathogens
strict pathogens:
lysogenic Corynebacterium diphtheriae Corynebacterium ulcerans (zoonosis)
- Pleomorphic rods - Form clumps that look like Chinese characters
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
CUTANEOUS diphtheria Upper RESPIRATORY tract infection
Mortality rate : genreal population: 5%–10% children younger than age 5 years and adults older than age 40 years: up to 20%
occurs through inhalation of saliva droplets that contain the bacteria
spread through direct contact with skin lesions of an infected host
Diphtheria
Exotoxin responsible for the disease symptoms
Diphtheria should be considered: - In unvaccinated patients with pharyngitis - low grade fever - cervical adenopathy - adherent gray exudate in throat
gene for toxin production occurs on the chromosome of the prophage, but a bacterial repressor protein controls the expression of this gene. The repressor is activated by iron. Toxin is synthesized only by lysogenic bacteria under conditions of iron deficiency.
EXOTOXINE of Corynebacterium diphtheriae
A B
A-B type of toxine
A -ctive fragment of toxine (Inhibits synthesis of human proteins)
B - ind toxine to the receptor & mediates delivery A to its target
Thic, grayish, adherent excudate = Pseudomembrane
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.
Diphtheria
LOCAL INFECTION
(throat, skin)
BUT SYSTEMIC EFFECTS
(heart, peripheral nerves)
Treatment of Diphtheria
- neutralization of toxin (horse serum antitoxin) - eradycation of bacteria ( penicillin, erytromycin) - immunization with toxoid
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
Erysipelothrix rhusiopathiae
Pleomorphic G+ rod distributed worldwide (animals, environment) uncomon human pathogen (occupational disease in people working with animals) erysipeloid (localized or septicemic) – zoonosis complications: endocarditis, abscess formation, osteomyelitis virulence factors: - hyaluronidase - neuraminidase - capsule like structure
Listeria monocytogenes
- widespread among animals and in an environment - growth at a broad temperature range (1- 45°C) - facultative intracellular bacteria - naturally resistant to cephalosporins
Listeriosis Although the number of cases of listeriosis is small, the high rate of death associated with this infection makes it a significant public health concern sporadic disease in healthy adults ( influenzae-like illnes with or without gastroenteritis), but is serious disease in patients from risk groups: - pregnant women - newborns - immunocompromised patients - eldery
Virulence factors: -internalins - listeriolysin O - intracellular survival - ActA protein
LISTERIOSIS
GIT self-limiting febrile gastroenteritis
syndrome
CNS - meningitis - meningoencephalitis - rhomboencephalitis
bacteremia and non-CNS focal infections focal bone infection
native and prosthetic joints infection osteomyelitis liver infection
splenic abscess others…
neonatal infections - early onset: granulomatosis infantisepticam - late-onset: - pneumonia - septicemia - meningitis
pregnant women: miscarriage, premature delivery
amnionitis,
Thank you for attention