Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
33 Cards in this Set
- Front
- Back
What are general characteristics of Gram Positive Cocci? Name the three important species for humans.
|
- circular or spherical in shape
- purple in a gram stain - (thick peptidoglycan layer) Staphylococcus epidermidis - normal flora of the skin and muscosae Staphylococcus aureus- pathogenic, often normal flora Staphylococcus saprophyticus- in environment and on skin, can cause urinary infections |
|
Name the general characteristics of Staphylococcus aureus.
|
- grows well on simple media (sugar, blood- agar)
- colonies 2-3 mm in 24 hrs. - 37 degrees - produce many toxins and enzymes - only true staph pathogen |
|
What toxins does Staphylococcus aureus make? And their characteristics.
|
1. Cytotoxins (alpha, beta, theta, gamma, P-V leukocidin): toxic to many cells- Leukocytes, erythrocytes, macrophages, platelets, fibroblasts. Spreads
2.Haemolysins: break down RBCs to get nutrient from blood, spread faster. lethal 3. Enterotoxin (A-E, G-I): superantigens, important cause of food poisoning (nausea, vomiting, cramps, pooping) 4. Exfoliative toxins (ETA, ATB): Scaled syndrome in infants 5. "Toxic shock syndrome Toxin 1": cause of toxic shock syndrome. - the more toxins S. aureus can make the more pathogenic it is. |
|
What enzymes do Staphylococcus aureus make?
|
1. Coagulase: coagulates fibrin (blood clots)
Coagulase test can be used for identification of S. aureus -most pathogenic strains of S. aureus produce this. Blocks macrophages from getting rid of bacteria 2. Beta- Lactamase (penicillinase): destroys penicillin. Others: hyaluronidase, staphylokinase. |
|
What are the clinical finding of S. aureus? ie. resistance, and symptoms
|
- many of the strains in the normal population and 85- 90% of strains isolated in the hospital are penicillin resistant.
- 15% of healthy indiv. carry S. aureus. InL anterier nares, axilla, perineum, on hands. - tends to produce localized purulent infections: pustules, boils, styes, conjunctivitis, otitis. - Serious: pneumonia, osteomyelitis, septicaemia, endocarditis and others, particularly in compromised/ immunosuppressed hosts ALSO: Food Poisoning. Toxic Shock Syndrome. Scaled Skin Syndrome. - important cause of hospital acquired infections. (stitche abscesses. infected wounds,generalized infections often resistant strains. |
|
What epidemiology does S. aureus present?
|
- strains are lysed by a number of diff bacteria viruses.
-Cells originating from the same parental cells are lysed by the same bacteriophage. - You can use "bacteriophage types" to track the source of infection |
|
What are preventative measures against S. aureus infections?
|
1. Washing hands
2. Strict adherence to aseptic techniques. in post op. 3. Education of personal. |
|
Describe Staphylococcus epidermidis.
|
- part of skin/ mucous membranes normal flora
- non- pathogenic. - effects immunocompromised patients (opportunistic) - post op. infections (brain, open heart) -endocarditis (heart valve insertion) -shunt infections - in neonates can be cause of necrotising enterocolitis. |
|
Name the general characteristics of Streptococci bacteria. And how are they subdivided?
|
- Gram positive
- pairs or forming chains - fastidious in nutritional requirements (blood agar) Subdivided by: Haemolytic properties -Alpha haemolysis: greenish brown zone of partial RBC destruction -Beta haemolysis: clear zone of complete RBC destruction around colonies * some strains are non- haemolytic Carbohydrate C- Antigen - extracted from the cell wall - sub divides into groups A-T (lancefield classification) - A is most common M- Protein (type of pilliae) - subdivides beta- haemolytic streptococci into over 70 serotypes - virulence factor: antiphagocytic, degrades complement C3b |
|
How does Streptococcus pyogenes present itself?
|
Acute tonsilitis: (strept infection)
- can lead to scarlet fever - rheumatic heart disease Skin infections - cellulitis - erysipelas - wound, burn, infection Fever: - post partum - post abortion Septicemia Complications (especially young patients: - acute glomerulonephritis - rheumatic fever (joints, heart valves) |
|
Name key characteristics of Streptococcus pyogenes.
|
- Group A, beta- haemolytic
- common in environment and humans |
|
Which toxins does Streptococcus pyogenes produce?
|
Streptolysins (O + S): beta- haemolytic and highly toxic for neutrophils and macrophages
Streptococcal pyrongenic exotoxins (Spes): - super antigens Spe A- C - causes the rash in scarlet fever |
|
What enzyme does S. pyogenes produce?
|
Hyluronidase: splits hyaluronic acid in connective tissue, helps infection spread
"flesh eating disease"= necrotizing fasciitis *not all strains can make this |
|
How many healthy individuals carry S. pyogenes? Is it penicillin resistant? How is it transmitted?
Prevention? |
- found 5-10%
- No, it is penicillin G sensitive - direct contact, nasal carriers, contaminated food - Education, strict asepsis in obstetric, early detection and treatment (because it is non transferable after 24 hrs.) |
|
Which bacteria (our example) is found in Streptococcus group B?
|
Streptococcus agalactiae
|
|
Describe Streptococcus agalactiae.
|
- Opportunistic
- found in vagina of healthy women - can cause neo natal infections |
|
Which neonatal infections does Streptococcus agalactiae cause?
|
1. Early Septicaemia (SIRS= whole body inflammatory state): respiratory distress/ shock at birth or within 24 hrs. High fatality rate
2. Delayed Meningitic Form: - 1-12 weeks later - better prognosis - can result in neurological damage |
|
Which bacteria (our example) is found in Streptococcus group D?
|
Streptococcus faecalis
|
|
Describe Streptococcus faecalis
|
- Enterococcus: normal flora of the human GI tract.
BUT can cause infections when introduced into tissues (urinary, endocarditis, meningitis) -often shows antibiotic resistance |
|
What are viridens Streptococci?
|
- classification for the undecided types.
- found in oral cavity of healthy individuals. - can cause problems in people with previously damaged heart valves -this can happen through dental surgery, or other cuts. |
|
What are some major characteristics of Streptococcus pneumoniae? besides that it has stupid spelling
|
- diplocci
- polysaccharide capsule has antiphagocytic properties - 90 distinct serotypes - found in naso-pharynx of healthy individuals |
|
What infections do Streptococcus pneumoniae cause?
|
Lobar pneumonia: most often an auto infection
-can spread as carrier -most frequent in the old, alcoholics, infancy - can be an epidemic Meningitis: most often in infant and elderly. - accompanied by bacteremia and septicemia |
|
Name two prevention methods for Streptococcus pneumoniae.
|
1. Programs for the elderly and alcoholics.
2. vaccination for those at high risk: (above + crowed living quarters) |
|
What are the key characteristics of Gram negative cocci ?
|
- pink stain
- thin peptidoglycan layer - outer membrane - round cells |
|
What are the general characteristics of Neisseria meningitidis?
|
- gram negative
- diplococci: 2 round cells stuck together -Lab isolation on chocolate agar (lysed blood) 5- 15% CO2 37 degrees -use selective media to differentiate from naso- pharynx (thayer- martin) - antiphagocytic polysaccharide capsules: 13 diff serogroups ABCXY W135 most common |
|
What are the infection specs. for N. meningitidis?
|
Carriers occasionally develop infection. or pass it to non-immune people who get it.
- only affects humans - affects young and crowed living quarters - epidemics occur occasionally |
|
What infections does N. meningitidis present as?
|
1. meningitis: purulent, high fatality rate if not treated fast
2. septicemia: high fever, rash, endotoxic shock. 3. If 1 and 2 together =complications = Water-fridrishesen syndrome: - bilateral adrenal cortical haemorhage - collaspe/ death in less than 24 hrs. |
|
What are preventions against N. meningitidis?
|
Penicillin is primary.
Vaccination: -conjugated vaccine for A, C, Y and W135 -infant for C |
|
Name two prevention methods for Streptococcus pneumoniae.
|
1. Programs for the elderly and alcoholics.
2. vaccination for those at high risk: (above + crowed living quarters) |
|
what are the general characteristics of Neisseria gonorrhoeae
|
- gram negative
- diplococci - 0.6 - 1 micrometers - lab: thayer- martin plates, damp CO2 - very sensitive to drying, temp changes |
|
What infections does N. gonorrhoeae cause? If untreated?
|
Genital:
Men: acute infection of urethra untreated- epididimitus, prostatitis Women: 50% asymptomatic cervicitis, urethra, rectum Untreated- PID (pelvis inflammatory disease), sterility Both Sexes: Rectal gonorrhea pharyngeal infection DGI: disseminated gonococcal infection- low grade fever, cutaneous infection, arthritis Neonatal: rare |
|
What is the diagnosis of N. gonorrhaeae?
|
Men: microscopy-
observe swabs of urethral discharge Women: necessary from endocervical urethral, anal swab |
|
How do you treat N. gonorrhoeae
|
Resistance has been seen from penicillin
- ceftriaxon, cefixime, ciprofloxin, azithromycin - Simultaneous treatment of partners essential - no vaccine available - one protein can go through genetic replacement - vaccine only against one strain. then changes |