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Patho > Bacteria > Flashcards

Bacteria Flashcards

1
Q

Gram negative structure

A

outer membrane containing Lipopolysaccharide (LPS)= endotoxin- induce septic shock
much thinner peptidoglycan with periplasmic space

beta lactamases are plasmid derived enzymes that chew up antibiotics in Gram Neg

gram neg lose the stain

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2
Q

Gram positive structure

A
  1. Thick multilayered peptidoglycan sheath outside of cytoplasmic membrane
  2. penicillin binding proteins found in both and strengthen peptidoglycan
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3
Q

Bacterial morphology

shape and arrangement

A

Cocci in clusters
* staphylococcus

Cocci in chains
* streptococcus

Coccis in pairs with pointed ends
* streptococcus pneumoniae

Cocci in pairs with kidney bean shape
* Neisseria

Rods (bacilli) with square ends
* bacillus

Rods with rounded ends
* salmonella

Rods with club shaped
* Corynebacterium

Rods fusiform
* Fusobacterium

Rods comma shaped
* Vibrio

Rods short pleiomorphic
* Hemophilus

Spirochetes- spiral shape with relaxed coil
* Borrelia

Spirochetes- spiral shape with tight coil
* Treponema

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4
Q

Microbiome

A

Distinctmicrobial communities that inhabit different host environments-> normal flora

established= permanent residents of associated body sites

Normal flora can cause disease when they gain access to other sites

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5
Q

Principles of pathogenesis

not all microorganisms are pathogens

A

Opportunistic pathogens-> usually normal flora /environmental organisms that do not cause disease except
* immunosuppression
* imbalance

Virulence- how many organisms does it take to cause disease
* letal dose vs infectious dose
* lower #= higher the virulence

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6
Q

terms related to infection

A
  1. Colonization- presence of a new organism that is neither normal flora nor the cause of disease
  2. Carrier individual colonized with potential pathogen in significant #s
  3. Inoculum- # of organisms to which a person is exposed
  4. Communicable/contagious- able to be spread form host to host
  5. Infection- invasion of tissues by microorganism that causes disease

Bacterial major mechanisms
1. Toxin producing-> exotoxins (secreted proteins), endotoxins (LPS in cell wall of G-), Superantigen (kind of exotoxin cuases release of larger amounts of cytokines from helper t and macrophages)
2. Invasion and inflammation-> enzymes (collagenase, hyaluronidase), virulence factors -> leads to inflammatory respons (erythema, edema, warmth, and pain)

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7
Q

Stages of infection

A
  1. Transmission from external source through a port of entry
  2. Evasion of innast host
  3. Adherence to mucous membranes
  4. Colonization by bacteria
  5. Disease symptoms caused by toxin or invasion inflammation
  6. Host responses innate and adaptive thru 3-5
  7. Progression or resolution of disease
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8
Q

Cant be seen in gram stain

MR CLMT

A
  1. Mycobacterium-> M. tuberculosis, ACID FAST STAIN
  2. Treponema pallidum-> DARK FIELD MICROSCOPY OR FLUORSCENT ANTIBODY
  3. Mycoplasma pneumoniae
  4. Legionella pneumophila-> prolonged counterstain
  5. Chlamydiae-> C. Trachomatis-> inclusion bodies in cytoplasm
  6. Rickettsiae-> Giemsa stain
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9
Q

role of oxygen

A

Obligate aerobes- pseudomonas aeruginosa
facultative anaerobes- e. coli
aerotolerant organisms- clostridium
microaerophiles-= campylobacter jejuni and h pylori
obligate anaerobes- Bacteroides fragilis

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10
Q

Medically important normal flora

LESS SAVE BB

A
  1. staphylococcus epidermis-> S. aureus, pseudomonas aeruginosa, propionibacterium, candida= skin
  2. Staphylococcus aureus-> nose
  3. Viridans streptococci-> eikenella corrodens= mouth
  4. Streptococcus mutans-> prevotella= dental plaque
  5. Anaerobes and Bacteroides-> gingival crevices
  6. V. streptococci= throat
  7. E. coli-> bifidobacterium, lactobacillus, enterococcus faecalis, clostridium= colon
  8. lactobacillus, e coli, group b strep-> c. albicans= vagina
  9. s. epidermis= urethra
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11
Q

exo vs endotoxin

A

Exo
* from gram +/-
* secreted from cell
* polypeptide
* highly toxic
* various clinical effects
* high Abs called antitoxins
* toxoids used as vaccines
* diseases: tetanus, botulism, diptheria

Endotoxin
* cell wall of negative
* not from cell
* lipopolysaccaride
* less toxic
* fever and shock clinical
* poor antigenic
* no toxoids and no vaccine
* diseases: meningococcemia, sepsis by gram negative rods

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12
Q

Superantigens (SAgs)

A

Causes:
1. massive proliferation of T cells
2. massive cytokine release

Results: fever, shock and death
SAgs bind to class 2 MHCs ag on APCs which bind a large subset of TcRs in a non specific manner

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13
Q

Lab cultures

A

Culture and sensitivity: blood, throat, sputum, csf, stool, urine, genital, wound, abscess
incubate in or without oxygen to detect aerobes vs anaerobes
Sensitivity testing-? MIC

Molecular tests:
Nucleic acid amplification test NAATs or PCR (gold standard and preferred)

Serologic tests:
Direct antigen detection-> F-AB
IgM, IgG

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14
Q

gram + cocci

staphylococcus and streptococcus

A
  1. S. aureus (+ coagulase)
    A. toxigenic superantigen- food poisoning,
    B. pyogenic- abscess= SSTI,
    C. Local- skin and soft tissue,
    D. Disseminated - sepsis, endocarditis, osteomyelitis, septic arthritis
  2. S. Epidermidis (- coagulase)- frequent culture contaminant
  3. S. Saprophyticus (-)- UTI

Catalase test= btwn staph + or strep -
Colagulase= between aureus vs epi

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15
Q

Staph skin infections

A

impetigo
hidradenitis suppurativa
cellulitis
necrotizing fasciitis
furuncle
paronychia
felon
carbuncle
blepharitis
folliculitis
bullous impetigo
abscess
mastitis

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16
Q

MRSA

Methicillin Resistant S. Aureus

A

Mech: mutation in penicillin binding protein
weird spider bite with necrosis

#1 cause of abscesses

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17
Q

Staphylococcal Scalded Skin Syndrome

Superantigen

A
  • Exfoliatin exotoxin= protease that targets desmoglein (intracellular adhesion protein)

perioral crusting and conjunctivitis

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18
Q

Toxic shock syndrome TSS

superantigen

A

Sx:
* fever
* rash- erythroderma
* mucosal involvement
* hypotension
* multi organ disease
* desquamation a= 2 weeks later

causes
* menstrual= tampons
* Non= postsurgical wounds, post partum, nasal packing
* pediatric skin lesions

  1. Staph auresu= TSS and enterotoxins; superantigens
  2. Group A strep-> streptococal pyogenic exotoxin A, B, both

TX
REMOVE FB

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19
Q

Streptococcus species

gram +

A
  1. S. pyogenes= A lancefield= Beta
  2. S. agalactiae= B lancefield= Beta
  3. S. pneumoniae= NA= Alpha
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20
Q

lancefield groups

based on antigenic cell wall polysaccharides

A
  1. Group C & G= asym colonizers and normal flora of upper airway= cause disease in immunosuppressed or chronically ill patients
  2. Group F= asym colonizers of oropharynx or gi cause severe suppurative infections including deep tissue abscesses, bacteremia, endocarditis

Group A- Streptococcus pyogenes
Group B- Streptococcus agalactiae
Group D- Enterococci, streptococcus bovis

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21
Q

Strep groups

A

S. pyogenes (PIT)
1. pyogenic
a. Local= IMPETIGO, CELLULITIS, PHARYNGITIS/TONSILLITIS
b. Disseminated= SEPSIS
2. Toxigenic= SCARLET FEVER TOXIC SHOCK
3. Immune mediated = RH & AGN

S. agalactiae (group b)= pyogenic= neonatal sepsis & meningitis
E. facalis (group d)= pyogenic= UTI, endocarditis
S. Bovis= pyogenic= Endocarditis
S. pneumoniae= pyogenic= pneumonia, otitis media, meningitis, sinusitis MOPS
Viridans strep= pyogenic= endocarditis

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22
Q

Toxigenic manifestation of Group A strep

Scarlet fever aka scarlatina

A

Day 1: flushed cheeks, rash in axilla and groin, pastia’s lines, coated whitish tongue sandpaper rash- erythrogenic toxin
Day 3: Circumoral pallor, strawberry tongue, + blanching test
desquamation

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23
Q

Necrotizing fasciitis

A

Action of hyaluronidase and exotoxin B

enzyme and toxin that breakdown hyaluronic acid

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24
Q

Immune Mediated patho of strep

Nonsuppurative Post-Strep sequlae

A

AGN
1. SXS: Edema and hypertension, cola colored urine
2. Labs: Hematuria and high rbcs and casts
3. tx: treat strep and support, most recover

a local infection with Group a strep -> weeks later = inflammation in an organ not affected by strep-> due to immunologic response to strep proteins that cross react with human tissues

RF
Major criteria
* Joints- polyarthritis- knees, ankles, elbows
* O- carditis
* Nodules- subcutaneous nodules
* Erythema marginatum- non pruritic rash on trunk and extremities
* Sydenham chorea

Minor criteria
* Crp elevated
* Arthralgia
* Fever
* ESR elevated
* Prolonged P-R interval
* Anamnesis of rheumatism-> previous rheumatic fever
* Leukocytosis

Evidence of preceding strep infection
1. antistreptolysin O increased
2. positive throat culture
3. positive GAS NAAT
4. recent scarlet fever

need 2 major or 1 major and 2 minor plus evidence of recent strep

25
Q

Streptococcus pneumoniae

B MOPS

aka pneumococcus diplococcus

A
  1. Pneumonia
  2. Otitis media
  3. sinusitis
  4. meningitis
  5. bacteremia
    aka pneumococcus diplococcus

over 80% decrease due to vaccines

26
Q

Gram - Cocci

Neisseriae MGM

A
  1. N. meningitidis- portal entry= respiratory tract= polysaccharide capsule with no beta lactamase
  2. N. gonorrhoeae- entry= gential tract= no capsule with some beta lactamase
  3. Moraxella= meningitidis, otitis media, sinusitis= yes beta lactamase and unknown capsule
27
Q

types of neisseria

A
  1. N. meningitidis= pyogenic= MENINGITIS= PCN G
  2. N. gonorrhoeae= pyogenic
    * local= gonorrhea= ceftriaxone + doxycycline
    * Ascending= PID-> mixed infextions so use ceftiaxone and doxy for chlamydia
    * Disseminated= disseminated gonococcal infection
    * Neonatal= conjunctivitis= ceftriaxone
28
Q

Meningococcemia

kids and teens

A
  1. Polysaccharide capsule-> immunity-> abs to cell wall ag
  2. Lipo-oligosaccharide endotoxin (LOS)-> shed in large amounts releasing cytokines-> shock

Presents as septic shock
* high fever
* hypotension
* petechial or purpuric rash
* Waterhouse- Friderichsen syndrome= adrenal insufficiency bc infarcted= MOST LIFE THREATENING FORM

29
Q

Meningococcal coagulopathy

A
30
Q

Meningococcal vaccines

A
  1. A, C, Y, W-135-> capsular polysaccharide-> carrier protein= diphtheria toxoid (conjugate)= MENACTRA OR MENVEO
  2. Same but = Menquadfi
  3. Same but = polysaccharide not conjugate= Menomune
  4. B= recombinant= TRUMENBA
  5. B groups covered= Recombinant= BEXSERO
31
Q

Gonnococcal infxn

SAT

A

Woman:
* Cervicitis- purulent vaginal discharge and intermenstrual bleeding-> complication is PID from ENDOMETRITIS OR SALPINGOOOPHORITIS

Men:
* Urethritis-> dysuria with purulent discharge -> lead to epididymitis

Overall:
* disseminated infection can be in both
* SXS: arthritis, tenosynovitis, and skin pustules

INTRACELLULAR GRAM NEGATIVE DIPLOCOCCI ON GRAM STAIN, NAAT NOT USED AS SCREENING LAB TEST

32
Q

Anaerobic bacteria of medical interest

A

Veilonella- Gram negative, non spore forming cocci= anaerobic diplococcus

33
Q

Gram + rods

fab 4- BLCC

A
  1. Bacillus= - anaerobic growth, + spore formation, + EXOTOXINS
  2. Clostridium= + , +, + EXOTOXIN
  3. Corynebacterium= -, -, + EXOTOXIN
  4. Listeria= -, -, -
34
Q

Bacillus sp.

A
  1. B. Anthracis= Anthrax= Exotoxin with 3 components
    **a. Potective ag, Edema factor=adenylate cyclase, Lethal factor= protease
    * Cutaneous anthrax- spores in soil enter wound
    * Pulmonary anthrax- spores inhaled into lung
  2. B. cereus= food poisoning= germinate in reheated rice-> produce exotoxins
    * TWO EXOTOXINS
35
Q

Clostridia

PT BC

A
  1. C. tetani= Tetanus= spores in soil enter wound= toxin blocks release of inhibitory transmitters= prevention- toxoid vaccine
  2. C. Botulinum= Botulism= exotoxin in food= blocks release of acetylcholine= prevention- proper canning: cook food
  3. C. perfringens
    * Gas gangrene- spores in soil- Lecithinase- DEBRIDE WOUNDS
    * Food poisoning- exotoxin in food- Superantigen= COOK FOOD
  4. C. diff- Pseudomembranous colitis= antibiotics suppress normal flora= cytotoxin damages colon mucoa= appropriate use of antibiotics
36
Q

Corynebacterium and Listeria

A

C. diphtheriae- diptheria- failure to immunize
L. monocytogenes-meningitis or sepsis

pleomorphic rods and metachromatic granules

37
Q

Listeria

A
  • can grow in refrigerator
  • foodborne-> ingest raw/unpasteurized milk products, deli meats, undercoooked meats, and ready to eat foods

Epidemiology= fetuses/newborns/pregnant women/immunocompromised

SXS:
* gastroenteritis- fever and chills, headache, watery diarrhea, myalgias, and abdominal cramps but limited vomiting

Prevention:
* use precooked food
* avoid raw milk, meat and seafood
* wash fresh fruits and veggies
* novaccine

38
Q

Gram - Rods

A
39
Q

Gram - rods

CVESSY

causing diarrhea

A

Enterotoxin mediated
1. Escherichia coli= no fever or WBC
2. Vibrio Cholerae= no fever or WBC in stool= COMMA SHAPED BACTERIA

Invasive inflammatory
1. Salmonella= Fever and WBC
2. Shigella= Fever and WBC
3. Campyhlobacter jejuni= Fever and WBC= COMMA OR S SHAPED BACTERIA
4. E. coli- enteropathic strains
5. Escherichia coli= fever, with/out UNDERCOOKED HAMBURGER-> HUS

Uncertain:
Yersinia enterocolitica- from pets

40
Q

ENTERIC GRAM- RODS OFTERN CAUSE OF UTI AND GRAM - SEPSIS

A
  1. E. coli- UTI and toxigenic disease
  2. Enterobacter cloacae
  3. Klebsiella pneumoniae
  4. serratia marcescens
  5. proteus mirabilis- uti in immunosuppressed
    6.Pseudomonas aeruginosa- opportunistic pathogen causing problems everywhere= biofilm producer

be familiar with it

41
Q

Gram - by disease

A

Escherichia= UTI, TRAVELERS DIARRHEA, NEONATAL MENINGITIS
Shigella- Dysentery
Salmonella- typhoid fever, enterocolitis
Klebsiella- pneumonia, UTI
enterobactor- pneumonia and uti
serratia- pneumonia and uti
proteus- UTI
yersinia- plague, enterocolitis, mesenteric adenitis

42
Q

Hemolytic uremic syndrome

bloody diarrhea from toxigenic E. coli and Shigella

A

Shiga toxin= HEMOLYTIC ANEMIA, THROMBOTIC THROMBOCYTOPENIA, RENAL FAILURE
Management: fluids and electrolytes
NO ABX OR DIARRHEA MEDS DUE TO INCREASE RELEASE OF SHIGA TOXIN
TX: dialysis, plasmapheresis, platelet inhibitors, epo

43
Q

Salmonella disease

salmonella enterica serotypes

3 forms of disease= SET

A
  1. Typhoid- high fever, delirium, tender abdomen, constipated= rose spots
  2. Enterocolitis- N/V to abdominal pain and diarrhea-> bloody
  3. Septicemia- fever with no enterocolitis -> sxs of affected organ-> osteomyelitis in kids
44
Q

Salmonella vs shigella

A

Diarrhea: Shigella + salmonella except typhi
invade bloodstream: all salmonella
Chronic carries: salmonella typhi
Vaccine: only typhi

45
Q

Typhoid fever

Foreign travel / origin

A

SXS: increasing fever, headache, weakness and fatigue
RASH: SALMON PINK OVALS ON TRUNK
DIARRHEA OR CONSTIPATION
extremely swollen abdomen

46
Q

Curved rods

A
  1. Vibrio cholerae- watery diarrhea- tx fluid replacement
  2. Campylobacter jejuni- bloody diarrhea- AB
  3. Helicobacter pylori- gastritis, peptic ulcer- AB
    * peptic ulcer disease
    * infxn reduce risk of esophageal adenocarcinoma due to ammonia production that reduces stomach acid
47
Q

Pseudomonas

lives everywhere

A
  • biofilm producer
  • otitis externa- diabetes
  • ecthyma gangrenosum
  • chronic lower respiratory tract infxns- CF
  • cellulitis- burn patients
  • hot tub folliculitis
48
Q

Bacteroides vs prevotella

gram - rod skin

A

B:
* anaerobe
* deep tissue infxt- peritonistis and abscess
* BELOW DIAPHRAGM
* sepsis

P:
* same but
* above diaphragm
* in mouth as normal flora

49
Q

Eikenella corrodens

Gram - rod skin

facultative anaerobe

A

HUMAN BITE WOUNDS
Vellonella can also be seen

50
Q

Gram - rods

respiratory

MOPES
PIP

A
  1. H. influenza- meningitis, otitis media, sinusitis, pneumonia, epiglottitis-> conjugate vaccine
  2. B. Pertussis- whooping cough ->severe paroxysms of coughing w/ vomiting= lead to lymphocytosis
  3. L. pneumophila- atypical pneumonia (contaminated water systems, spas)
51
Q

Pertussis stages

A
  1. Catarrhal stage- 1-2 wks, URI and contagious
  2. Paroxysmal stage- worsening cough, inspiratory whooping, cyanosis, lymphocytosis, post tussive emesis
  3. Convalescent stage- cough lessening- may develp second respiratory infxn or get better
52
Q

gram - to recognize

RECOGNIZE ONLY DUMMY

A

Klebsiella pneumoniae
enterobacter cloacae
serratia marcescens
* primary pneumonia and utis
Proteus mirabilis
morganella
providencia
* utis

53
Q

Gram - Zoonoses

from animals to humans

A
  1. Brucella- Brecellosis- diary products
  2. Francisella- Tularemia- rabbits and deer-> ticks transmit
  3. Yersinia- Plague- rodents- flea bite
  4. Pateurella- Cellulitis- cats, dogs
  5. Bartonella henselae- cat scratch disease & bacillary angiomatosis,- cats
54
Q

Brucellosis

unpasteurized products

A
  1. Fever-> undulating
  2. Diaphoresis, myalgia, arthralgia, malaise
  3. fatigue, weakness
  4. cough, abdominal pain, low back pain
  5. severe scrotal swelling
55
Q

Tularemia

A
  • chills, fever
  • anorexia, malaise
  • headache, joint stiffness, muscle pains
  • red spot on skin-> growing to become a sore/ulcer

from wild rabbits transferred by ticks

56
Q

Yersinia pestis

black death

A

bubonic plague
squirrel and rodent source

57
Q

Plague symptoms

A

Bubonic
* large swollen lymph nodes in groin, armpit, neck

Septicemic
* fever chills, weakness, abdominal pain, bleeding from orifices, shock

Pneumonic
* spread via respiratory droplets
* cough, hemoptysis, dyspnea, N/V/Fever, weakness

58
Q

Bartonella henselae

Cat-scratch fever

A

SXS: blister at site, fatigue, headaches, low grade fever
PE: regional lymphadenopathy
Complications: encephalopathy, neuroretinitis, osteomyelitis
TX: doxy

Patho (4 decks)

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