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Microbio > Lecture 19 > Flashcards

Lecture 19 Flashcards

1
Q

4 genera of pyogenic cocci

A

Staphylococcus
Streptococcus
Enterococcus
Neisseria
(Ness)

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2
Q

Pyogenic

A

Bacteria that stimulate the formation of pus

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3
Q

Pus caused by

A

Neutrophils

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4
Q

Staphylococcus characteristics

A

Gram positive, spherical cells, arranged in clusters
No spores or flagella
Common inhabitants (microbiota) of swim and mucus membranes

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5
Q

Staphylococcus species

A

Over 40,12 of them colonize humans, 3 of major medical importance

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6
Q

3 staphylococcus species of major medical importance

A

S. aureus
S. epidermidis
S. saprophyticus

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7
Q

S. Aureus

A

Primary pathogen, facultative anaerobe, catalase positive, 10-46°C but 37°C ideal makes it good on famines
* most resistant of non-endospore forming pathogens
Can with stand 7.5 - 10 percent salt, pH 4-10, drying (thick pg layer), resistant to some antibiotics (MRSA VRSA), heat up to 60°C

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8
Q

S. aureus virulence factors (6)

A

Protein A- causes antibodies to bind f(c) region so it doesn’t stimulate an immune response
Coagulase- enzyme that clots blood, restricts blood flow to area preventing neutrophil * used diagnostically to differentiate S. aureus from other staphylococci
Hyaluronidase- digests hyaluronic acid in the basement membrane of tissues to infect deeper since non-motile aka spreading factor
Staphylokinase- digests blood clots
Lipase- digests lipids and oils on skin as nutrition and to more easily colonize skin
Penicillinase- antibiotic resistance enzyme, inactivates beta-lactam ring

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9
Q

S. aureus exotoxins

A

Hemolysins- lyse red blood cells that contain lots of protein and iron to eat
Leukocidins - lyse white blood cells
Enterotoxins- exotoxins that act on GI tract inducing nausea, vomiting, diarrhea
Toxic shock syndrome toxin (tsst)- systemic effects fever, vomiting, rash, shock from major vasodilation BP drops brain doesn’t relieve enough blood

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10
Q

3 types staphylococcal diseases

A

Localized pyogenic, systemic, toxigenic infections

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11
Q

Localized staph aureus infections

A

Invades skin through wounds, follicles, and glands
Causes abcess/boils (inflamed lesion with a core of pus) which either go away on their own or need to be drained

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12
Q

Furuncle

A

Abscess resulting from an infected hair follicle

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13
Q

Carbuncle

A

Deeper access formed by an aggregation of furuncles

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14
Q

Impetigo

A

Localized S. aureus infection, infection of the epidermis characterized by honey-crusted skin lesions
Common in newborns and young children

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15
Q

Systemic staph aureus diseases

A

Usually caused by spreading from local cutaneous infection to other sites via bloodstream

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16
Q

Bacteremia

A

Systemic staph aureus infection, the presence of viable bacteria in the blood

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17
Q

Osteomyelitis

A

Systemic Staph aureus Infection of the bone creates pus inside bone

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18
Q

Endocarditis

A

Infection of inner heart lining and values
Can cause permanent valve damage and mur murs

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19
Q

3 toxigenic staph aureus diseases

A

Food intoxication, scalded skin syndrome, toxic shock syndrome

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20
Q

Food intoxication

A

Toxigenic staph aureus disease caused by hear stable enterotoxins produced by the bacteria, associated with foods rich in carbs like cream, pastries, potato salad, processed meats

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21
Q

Acute vomiting

A

Vomiting that occurs 1-6 hours after ingestion

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22
Q

Scalded skin syndrome

A

Toxigenic staph aureus disease, grows on skin and secretes exfoliative toxin causing upper skin layer separation
Young kids + newborns prone

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23
Q

Toxic shock syndrome

A

Toxigenic staph aureus disease, first identified through tampon use, causes fever, vomiting, rash, and shock
Some women have staph aureus in the vagina that release this

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24
Q

Most important test for distinguishing staph aureus from other staphylococci

A

Catalase test, Also helps differentiate staph and streptococcus

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25
Q

Coagulate test

A

Added to rabbit serum either clumps or does not
Clumping = positive staph aureus
Negative= other staphylococcus species or streptococcus

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26
Q

CNS

A

Coagulase negative staph

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27
Q

Streptococcus

A

Gram positive, spherical/ovoid, arranged in bead-like chains
Non-spore forming non-motile
Common inhabitants of throat and nasopharynx and sometimes skin
Facultative anaerobes, catalase negative, fastidious needs enriched media,
Small round colonies that are translucent or gray

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28
Q

Allows for differentiation of streptococci from staphylococci

A

Streptococci are catalase negative

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29
Q

Lancefield classification system

A

Rebecca craighill lancefield, based on cell wall carbohydrates displayed by each, 17 different alphabetical groups A to O

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30
Q

Group A strep

A

Strep pyogenes, primary human pathogen, 95% all streptococcal diseases

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31
Q

Gas

A

Group A strep

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32
Q

Group B

A

Streptococcus agalactiae, responsible for neonatal infections, some moms have it in birth canal
Can cause neonatal meningitis and sepsis blood infection

33
Q

Group D strep

A

Enterococcus from large intestine or fecal matter causes several human infections especially nosocomial infections and UTIs
Feces contaminates bed pans, catheters, etc

34
Q

Beta hemolytic

A

GAS, GBS, GCS

35
Q

Alpha hemolysis

A

Incomplete hemolysis, strep pneumonie and viridans strep

36
Q

Gamma hemolysis

A

No hemolysis, some GDS

37
Q

Strep pyogenes/group A strep

A

Strict parasite, inhabits throat/nasopharynx sometimes skin mucus membranes
Surface antigens: 1. C-carbohydrates unique technic acids used for Lance field, protects against lysozyme 2. M protein for fimbriae
Exoenzymes: 1. Streptokinase 2. Hyaluronidase
Exotoxins: 1. hemolysins 2. Erythrogenic toxin- exotoxin causes fever and rash in strep throat infections

38
Q

Determine if impetigo caused by staph or strep

A

Catalase test or with microscope

39
Q

Erysipelas

A

Infection in the dermis caused by a deep wound or incision
Forms red hot rash via mast and releasing histamine

40
Q

Streptococcal pharyngitis

A

Localized strep pyogenes
Multiplies in tonsils or pharyngeal mucous membranes
Causes redness, edema, extreme tenderness, painful swallowing, fever, headache
Purulent exudate (pus) over the tonsils

41
Q

Scarlet fever

A

Systemic strep pyogenes, lysogenic strain releases erythrogenic toxin causing systemic bright red rash over body (scariatina) and strawberry tongue

42
Q

Rheumatic never

A

Systemic strep pyogenes, if bacteria enters the bloodstream it can attach to and damage heart valves leading to heart disease and murmurs

43
Q

Necrotizing fascitis

A

Group A strep, flesh-eating bacteria, virulent group A toxins and enzymes that destroy tissues
Strep pyogenes enters through a break in the skin
Tissues destroyed in hours

44
Q

Necrotizing fasciitis progression

A

Cellulitis with no clear margins+ painful develops, then bullae (large blisters) form after a few hours organism releasing toxins, then gangrene which is permanent tissue death, massive tissue necrosis, systemic symptoms, multi-system organ failure

45
Q

Enterococcus/group D strep

A

Enterococcus faecalis and faecium found in large numbers in the large intestine, normal microbiota
Cause opportunistic infections of the urinary tract, wounds and bacteremia
Endogenous from own intestines

46
Q

Risk for enterococcus/strep D

A

Patients who have been hospitalized for prolonged periods or treated with broad spectrum antibiotics that enterococci are resistant to like VRE

47
Q

Viridans streptococci

A

Alpha hemolysis, most numerous resident of oral cavity, nasopharynx, GI tract, and skin
Dental or surgical procedures can facilitate entrance

48
Q

Strep mutans

A

Dental caries and tooth abscess, opportunistic

49
Q

Subacute endocarditis

A

Blood borne bacteria settle and grow in inner heart lining and values

50
Q

Viridans group can cause

A

Bacteremia, meningitis, and abdominal infection

51
Q

Streptococcus pneumoniae/ pneumococcus

A

Significant human pathogen, 60-70% all bacterial pneumonias, a main cause bacterial meningitis, lancet shaped cells in diplococcus or short chains
Humans principal reservoir carrying in nasopharynx

52
Q

Streptococcus pneumoniae virulence factors

A

Pronounced capsule present in all pathogenic strains of strep pneumoniae, 90 different capsular types found with Quellung test, subunit vaccines target capsular strains

53
Q

Quellung test

A

Capsular swelling test using antiserum specific for a capsule type, can be used to figure out strain patient has in lungs

54
Q

Strep pneumoniae vaccine for infants

A

Prevnar 13 for infants, 13 capsules

55
Q

Strep pneumoniae vaccine for adults

A

23 and older

56
Q

What allows strep pneumoniae to enter lower respiratory tract

A

Presence of compromising factors that impair mucociliary motion, cough reflex, etc
Once in the lungs the bacteria can evade non-specific host defenses like phagocytosis due to its large capsule

57
Q

1 cause strep pneumoniae

A

Ottis media, a middle ear infection that is very common in US children, pneumococcus gains access via the Eustachian tube (connects ear to throat)

58
Q

Most susceptible to strep pneumoniae

A

Children under 2 because of shorter rustachian tube

59
Q

Neisseria

A

Aerobic, gram negative diplococci with flattened adjacent sides, non-spore forming and no flagella, most opportunistic colonize mucous membranes, pathogenic ones are strict parasites

60
Q

Pathogenic neisseria

A

Strict parasite, capsules and fimbriae as main virulence factors, very fastidious

61
Q

Neisseria may be cultured on

A

Chocolate agar containing heated blood and/or hemoglobin for enrichmen, heating breaks open blood cells for them since they’re non hemolyti

62
Q

Selective media for neisseria

A

Thayer-martin agar containing 3 antibiotics that inhibit other microbes

63
Q

2 primary pathogenic neisseria

A

Neisseria ghonorrhoeae
Neisseria meningitidis

64
Q

Neisseria gonorrhoeae

A

Aka gonococcus, eriological agent gonorrhea, one of top five STDs worldwide, strictly human infection, no more than 1-2 hours on formites, asymptomatic in 10% males and 50% females

65
Q

Neisseria gonorrhoeae virulence factors

A

Fimbriae
IgA protease- destroys the IgA secretary antibody on host mucosal surfaces
Capsule blocks phagocytosis
Endotoxin Los highly toxic

66
Q

Gonorrhea in males

A

Infection mostly restricted to urethra causing urethritis (inflamed urethra) and painful urination
Prolific pus production
Could resolve on own, occasionally spread to prostate and epididymis leading to infertility

67
Q

Gonorrhea in females

A

Primary site of infection is cervix but can be isolated from urethra, vagina, and rectum
Vaginal discharge, painful urination, vaginitis, urethritis, and salpingitis (inflammation of the fallopian tubes)
PID (pelvic inflammatory disease)

68
Q

Gonorrhea in females can lead to

A

Infertility or ectopic pregnancies later in life due to scarring of fallopian tubes

69
Q

Gonorrhea in new barns

A

Infected as pass through birth canal, eye inflammation, purulent conjunctivitis which can lead to blindness, prevented by prophylaxis afte birth using silver nitrate or other antibiotic drops
Pregnant women should he screened

70
Q

New cases gonorrhea each year

A

500,000 every year in US

71
Q

Does prior infection provide long-term immunity for gonorrhea

A

No, lots of strains

72
Q

Neisseria meningitidis

A

Aka meningococcus causes epidemic cerebrospinal meningitis, highest incidence kids under 5, 2nd most common cause in adults (after strep pneumoniae), human reservoir in nasopharyny, spreads within families and communities

73
Q

Neisseria meningitidis virulence factors

A

Capsule, fimbriae, IgA protease, endotoxin LOS

74
Q

Neisseria meningitidis transmission

A

Aerosolized respiratory droplets especially in crowded situations

75
Q

Neisseria meningitidis entrance and progression of meningitis

A

Enters respiratory tract, crosses mucosal barrier, enters blood stream, bacteremia allows it to travel to brain and cross BBB, establish infection in meninges
Headache, fever, nausea, vomiting, stiff neck
Endotoxin release can cause hemorrhage and shock

76
Q

Meningitis mortality

A

100% untreated, drops to 10% with treatment

77
Q

Meningitis diagnosis

A

CSF specimen cultured or gram stand

78
Q

Meningitis vaccine?

A

Meningococcal vaccine, subunit vaccine using capsular polysaccharides, recommended for all ages especially during outbreaks dermis, military base, etc
Antibiotic prophylaxis for those with significant exposure to the sick

Microbio (14 decks)

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