Gram Positive Rods Flashcards
Non-Spore Formers
- Listeria
^ L. monocytogenes - Corynebacterium
^ C. diptheriae
Spore Formers
- Bacillus AEROBIC
^ B. anthracis
^ B. cereus
- Clostridium ANAEROBIC
^ C. perfringens
^ C. botulinum
^ C. tetani
^ C. difficileBranching Gram + Rods
- Actinomyces ANAEROBIC
- Nocardia AEROBIC
Lysteria
Non-Spore Former Gram + Rod - short slender rods - intracellular parasites - tumbling motility - small B-hemolytic colonies - found in livestock
Listeria monocyogenes
Gram + Rod
Only species pathogenic to humans
- infections usually food borne
- grows at 4C - REFRIGERATION DOES NOT HINDER GROWTH
- found in those with suppressed immune systems
- pregnant women, babies, old people
Listeria monocytogenes
Disease
- Septicemia
- Gastroenteritis
- Meningitis
- Fetus-spontaneous abortions
- Neonatal meningitis
- common cause; transferred during birth
Disease type dependent on where the infection occurs
L. Monocytogenes Pathogenesis
- Phagocytosed
- Grows in cytoplasm
- Reorganizes cellular actin for locomotion
L. Monocytogenes
Treatment and Prevention
- Antibiotics
- Proper food handling
- Expiration Dates
Corynebacterium
- Widely distributed in nature
- Pleomorphic: many sizes and shapes
- Palisading (arranged parallel)
- Irregular staining
- Non-motile
- Unencapsulated
- Facultative anaerobes
- Growth on standard media (blood agar)
Corynebacterium diphtheria
- Infection of URT
- grey PSEUDOMEMBRANE forms covering throat and nose
- Pathogenic strains have exotoxins
- cause CNS and cardiac problems
- inhibits protein synthesis (EF-2)
- On phage: must integrate into chromosome
- Small grey colonies on blood agar
- childhood vaccination
C. Diphtheria
Clinical Significance
Respiratory
- localized in throat; spread via droplets
- Toxin inhibits protein synthesis
- Heart and CNS issues
- PSEUDOMEMBRANE
Cutaneous
- from puncture or deep cut
- grey membrane
- rare: exotoxins causing tissue necrosis
Asymptomatic carriersC. Diphtheria
Identification
Clinical Observation
- pharyngitis
- fever
- swelling of neck
- GREY PSEUDOMEMBRANE
Definitive
- culture
- TINSDALE AGAR (Potassium TELLURITE)
Assay for toxinC. Diphtheria
Treatment and Prevention
Treatment
- antibiotics
- neutralize toxin
Prevention
- Toxoid immunization (antigenic)
- childhood immunizations
- DTaP
- Diptheria, Tetanus, PertussisBacillus
Large Gram + Rod
- aerobic
- ubiquitous in soil or water
- can have airborne spread
B. cereus & B. anthrax
Cereus - food poisoning
Anthraces - anthrax from livestock
Closely related; differ in virulence factor toxin
Bacillus cereus
- MEDIAL Spore (middle of bacteria)
- Found in GI tract and nature
- Virulence Factors:
- Enterotoxins
- Spores
- Food poisoning
- Large and feathery colony
- B-hemolytic
- Motile
B. Cereus
FRIED RICE SYNDROME: spores not killed by boiling
-germinate if not refrigerated properly
- produce ENTEROTOXINS
- food poisoning
- 2 types enterotoxins
^ Heat Stable: Vomiting
^ Heat Liable: diarrheaB. Anthracis
- Widely distributed in nature
- primarily in livestock; humans infected through contact
- Virulence factors:
- Capsule
- Spores: medial spores
- Exotoxins that allows cell and tissue destruction
- EXTREMELY VIRULENT
- Bamboo sticks
Anthrax Disease
- Cutaneous: spores enter through cuts
- PAINLESS ulcer with a black center (ESCHAR)
- Systemic
- INHALATION: PULMONARY
- inhale; presents with fever, chest pain, shortness of breath
- 100% mortality if not treated
- GI
- infected meat; GI symptoms
B. Anthracis
Pathogenesis
- Capsule
-PROTEIN; poly-D-glutamic acid - Two Exotoxins
- EDEMA FACTOR: elevates intracellular cAMP = severe edema
- LETHAL FACTOR: kill signal transduction; apoptosis of macrophages
^ necrosis
- PROTECTIVE ANTIGEN: delivers exotoxins
- needed for toxin factor effects!
B. Anthracis
Growth and Identification
- Medial oval spores
- Non-hemolytic
- Irregular borders
- Non-motile
- Encapsulated
- Detection biz immunofluorescence assay
B. Anthracis
Treatment and Prevention
Treatment: antibiotics
Prevention: vaccine if high risk; prophylaxis antibiotics if exposed
ONLY KILL SPORES WITH AUTOCLEAVING
B. Anthracis
Bioterrorism
Why?
- ease- very hard to detect
Clostridium
TERMINAL SPORES
- found in nature
- obligate anaerobes
- motile
- Virulence Factors
- capsules
- potent exotoxins
Gram Positive Rods
Non-Spore Formers - Corynebacterium - Listeria - Lactobacillus - Actinmyces - Nocardia Spore Formers - Bacillus - Clostridium
Spore Forming Gram Positive Rods
Aerobic
- Bacillus
- anthracis
- cereus
Strict Anaerobes
- Clostridium
- perfringens
- tetani
- botulinumNon-Spore Forming Gram Positive Rods
- Coryenbacterium
- Listeria
- Lactobacillus
- Actinomyces
- Nocardia
Clostridia Species
- C. Perfringens
- C. botulinum
- C. tetani
- C. Difficile
C. perfringens
- Histotoxin: tissue destruction
- Gas gangrene, food poisoning
- normal flora of vaginal and GI tract
- cause gas gangrene (NECROSIS)
- high mortality
Clostridium perfringens
Disease
CRUSHING INJURY GAS GANGRENE - tissues and muscles - spores enter body; toxins cause death - fermentation of tissue produces gas (gas=virulence factor) - more dangerous; fatal in days CELLULITIS - tissue only -similar but no muscle damage FOOD POISONING
C. Perfringens
Pathogenesis
- Secretes exotoxins
- Alpha Toxin REQUIRED for virulence; degrades cell membranes & lyses cells
- Hydrologic enzyme facilitate necrosis
- Enterotoxins: GI illness
C. Perfringens
Identification
- clinical presentation
- anaerobic culture on blood agar
- double zone of hemolysis in blood agar
C. Perfringens
Treatment and Prevention
- immediate removal of foreign matter
- debride and remove tissue
- EXPOSE WOUND TO O2
- amputate
- high doses antibiotics
Clostridium botulinum
- Ubiquitous spores
- Produces strong neurotoxin
- muscles unable to flex or tense
- FLACCID paralysis
- progressive paralysis leads to respiratory failure
C. Botulinum
Clinical Significance
- Foodborne (classic) botulism: most common
- eat toxin
- Wound botulism
- wound contaminated with cells or spores and produces toxins
- Infant botulism: FLAPPY BABY SYNDROME
- immature microbial flora (aka immature immune system) makes kiddos susceptible
C. Botulinum
Treatment and Prevention
Treatment: Antitoxin and Antibiotics
Prevention: Toxin inactivated by boiling; AUTOCLEAVING of SPORES
Clostridium tetani
Tetanus
OPPOSITE TO BOTULISM
- found ubiquitously in soil
- spores enter via puncture wounds/trauma
- produces neurotoxin which prevents muscle relaxation
- SPASTIC paralysis
- Rare
- immunization
- extremely anaerobic
Tetnus
- initial spasms at site of infection
- lockjaw syndrome
- spreads elsewhere
- 50-60% mortality due to respiratory failure
Tetanus
Treatment and Prevention
Treatment: - start immediately - antitoxin - hyper immune immunoglobulin - antibiotics Prevention: - toxoid vaccine - DTaP with booster Post Exposure Prophylaxis
Clostridium difficile
- minor component of normal colon flora
- opportunistic
- found often in hospitals
- because spores = hard to eradicate
C. Difficile
Disease
- aggressive healthcare pathogen
- majority of infections involve healthcare
- antibiotics increase risk by disrupting normal colonic flora
- opportunistic pathogen
- PSEUDOMEMBRANOUS COLITIS
- GI symptoms that can progress to toxic megacolon, sepsis, and death
C. Diff
Treatment and Prevention
Treatment: stop predisposing drug (antibiotics); reconstitute normal gut flora
Prevention: reduce use of associated antibiotics
Actinomyces
- Ubiquitous in environment and body (normal flora)
- Branching
- Grows anaerobically
- Pathogenic in immunocompromised individuals
Actinomyces
Epidemiology
- chronic, slow developing infections
- no person to person spread
- low virulence; only causes disease if mucosal barrier is disrupted
Actinomyces
Clinical Significance
Yellow pus and abscesses
Actinomyces
Identification
- “sulfur granules” in pus
- grow in rich media anaerobically
- slow growth
Actinomyces
Treatment and Prevention
- antibiotics
- lasting months
- surgical debridement and drainage
Nocardia
- breathe in/breaks in skin
- strictly Aerobic
- low virulence; no person to person spread
- effects mostly immunocompromised
- opportunistic organism
Nocardia
Clinical Significance
- Pneumonia in immunosuppresed patients
- Abscesses and necrosis but NO YELLOW PUS!
- Avoids phagocytosis via secreted enzymes
- Can live in macrophage
- Can spread to BRAIN and KIDNEYS
Norcardia
Identification
- Poorly stained with Gram stain
- Irregular staining
- No sulfur granules
- Gram +
