Gram Positive Pathogens - Robison Flashcards
Staphylococcus- General Facts
In every human’s microbiota
Can be oportunistic pathogens
What is the structure and physiology of Staphylococcus?
Gram positive cocci are non-motile, faculative aerobes, with irregular clusters
Catalase Positive
Describe S. epidermidis
most common organism on the surface of skin
coagulase negative, mannitol negative, and mostly opportunistic infections
Describe S.aureus
carried by 30-50% of healthy population
coagulase positive, mannitol positive, and more virulent
What are the three categories of Staphylococcal disease?
Non invasive - indegestion
Cutaneous - various skin conditions
Systemic
What are the Staphylococcal defenses against phagocytosis?
Inhibits the complement system by covering surface with protein A
Converts fibrinogen to fibrin with coagulase to not form blood clots; keeps its self surrounded by fibrin capsule
Which bacteria produces more toxins? S. aureus or S. epidermis?
S. aureus
What are cytolytic toxins?
pore forming toxins
What are exfoliative toxins?
causes skin cells to seperate from eachother
What are toxic- shock syndrome toxins?
causes toxic shock syndrome due to superantigen
What are some skin related diseases caused by staphylococus?
impetigo, boils (furuncle), carbuncle, scalded skin syndrome
What are some systemic diseases caused by staphylococcus?
TSS, bacteremia, endocarditis, pneumonia, osteomyelitis
Treatments for staphylococcus diseases
Methicillins for most infections
Vancomycin for MRSA
How are staphylococcus infections and diseases mostly passed?
endogenous source and easily transmitted by contact
What is the morphology and physiology of streptococcus?
Gram positive coccus arranged in pairs or chains
Aerotolerant anaerobes
What is in the Group A Streptococcus and what are characteristics?
S. pyogenes
pathogenic strains often form a capsule
can cause disease if the normal microbiota is depleted, large amounts develop, or specific immunity impaired
What causes pathogenicity in streptococcus Group A?
Protein M interferes with opsonization and lysis
Certain enzymes
Pyrogenic toxins stimulate macrophages and helper T cells to release cytokines
Streptolysins lyse RBC, WBC, and platelets
What are some diseases caused by group A streptococcal?
phayngitis, scarlet fever, pyoderma, erysipelas, streptococcal TSS, necrotizing fasciitis, rheumatic fever, glomerulonephritis
How is GAS transmitted?
respiratory droplets, direct, and indirect contact
What are some characteristics of streptococcus pneumoniae?
Gram positive cocci that mostly forms in pairs but also can form chains
usually colonizes in the mouth and phayrnx bu can cause disease if in the lungs
Disease is the highest in the children and elderly
What is the most significant human pathogens?
streptococcus pneumoniae
What is the pathogenicity of streptococcus pneumoniae?
polysaccharide capsule that binds factor H to inhibit the complement pathway
protein adhesin helps binding to cells
Secretory IgA protease
pneumolysin is a pore forming toxin
What are some diseases that streptococcus pneumonia can cause?
pneumococcal pneumonia
sinusitis and otitis media
bacteremia and endocarditis
pneumoccal meningitis
What is the diagnosis, treatment and prevention of streptococcus?
Diagnosis: gram stain of sputum smears
Treatment: penicillin or cephalosporins
Prevention: vaccines
What are enterrrococcus?
found in the human colon
Short chains and pairs that lack a capsule but can grow in basic conditions
resistant to mobt beta-lactams, sulfa drugs, and VRE, erythromyocin, and tetracycines
What are characteristics of bacillus?
Gram positive bacilli that occur in pairs, singles, or chains
forms endospores
What is anthrax?
gram positive endospore forming bacillus
has three component toxin
What are the three forms of disease of anthrax in a human?
Inhalation- causes capillary thrombosis and cardiovascular shock
Gastrointestinal- ingestion of spore; rare
Cutaneous- marked by necrotic skin ( eschar); usually not fatal
What is the diagnosis, treatment, and prevention of anthrax?
Diagnosis- presence of non motile gram-positive bacilli in lungs or skin
Treatment- ciproflaxacin and other antimicrobials
Prevention: animal control and vaccines
What are characteristics of clostridium?
gram positive anarobic endospore forming bacilli
Describe characteristics of clostridium perfringens
Usually in digestive tracts
Produces 11 toxins
Causes food poisoning and gas gangrene
What are the treatments for gas gangrene?
removing dead tissue and admistering large doese of penicillin and hyperbaric oxygen
prevent with proper cleaning and prevent gas gangrene
What is botulism?
Disease caused by clostridium Flaccid paralysis treatment is polyvalent antitoxin Prevented by proper food preparation and storage procedures Toxin is destroyed by heat
What are the three forms of botulism?
Food-borne
Infant
Wound
What is clostridium tetani and what does it cause?
Endospore forming obligate anaerobic gram positive rod
causes tetanus - spasms and contractions that can result in death “lock jaw and spastic paralysis”
treated with vaccines
Describe bacteroides fragilis
Easiest to grow with a polysaccharide capsule
anaerobes
Describe Listeria monocytogenes
Anaerobes
gram positive; non spore forming
can live within cells, doesnt form toxins
resistant to heat, cold, salt, and pH
infections are caused by ingestion of contaminated milk or meat
Treated with ampicillin and prevented by pasteuriationa and proper cooking
What is corynebacterium and what does it cause?
On plants, animals, and humans
colonized in skin respiration, GI, urinary, and genital tract
Causes diptheria
How is diptheria transmitted and what are its symptoms?
through respiratory drops and skin contact; diptheria toxin causes symptoms
Causes dead cells and fluid to thicken and harden in the respiratory tract
cutaneous diphtheria causes cell death
Can also cause damage to heart and CNS;
What is the Schick test?
test immunity to diphtheria
What is propionibacterium and what does it cause?
Small, Gram-positive rods that are found in the skin
Causes acne
Describe actinomyces
anaerobic gram positive filamentous bacilli
found in dental plaque
treat with amoxicillin
