Bacteria Flashcards
(128 cards)
1
Q
What color do gram positive bacteria stain?
A
purple
(“I’m positive it’s purple”)
2
Q
What color do gram negative bacteria stain?
A
pink
(“Red marks are negative”)
3
Q
What are the steps of gram staining?
A
1) crystal violet (primary dye): gives gram positive bacteria their purple color
2) iodine (dye trapping agent)
3) alcohol (decolorizer): washes away gram negative bacteria’s lipid coat, removing violet stain
4) safranin (counterstrain): gives gram negative bacteria their pink color
4
Q
Describe the features of gram positive bacterial envelope:
A
- thick peptidoglycan wall w/ embedded techoic and lipoteichoic acids (used in serologic bacterial identification)
- retains crystal violet stain (purple)
5
Q
Describe the features of gram negative bacterial envelope:
A
- thin peptidoglycan layer w/ lipopolysaccarides on the surface (partially washes away w/ alcohol prep)
- LPS contains lipid A that can act as endotoxin, sometimes exposed upon death of bacteria
- stains pink
6
Q
What 2 groups of bacteria comprise grain stain exceptions?
A
- gram variable bacteria: increases w/ culture age, seen in clostridium and bacillus species
- acid fast bacilli: contain mycolic acids, gram stain cannot penetrate waxy cell wall, use acid fast stain, example is mycobacterium tuberculosis
7
Q
What are the common morphologies of bacteria w/ exmaples?
A
- cocci: spherical balls; diplococci (streptococcus pneumonia), streptococci (streptococcus pyogenes), staphylococci (staphylococcus aureus)
- bacilli: rod shaped; rods (E. coli), rods in chains (bacillus anthracis), club shaped rob (corynebacterium diphtheriae)
- coccobacillus
- spirochetes: helical shaped; H. pylori, treponema pallidum (syphilis)
- spirilla: S-shaped
- comma shaped: vibrio species
- filamentous: thread-like; nocardia species
- pleomorphic: no particular shape
8
Q
What are the 6 major disease causing gram positive bacteria?
A
- staphylococcus
- streptococcus/enterococcus
- bacillus
- clostridium
- corynebacterium
- listeria
9
Q
How do you differentiate the gram (+) bacteria in terms of shape?
A
- cocci: staphylococcus, streptococcus/enterococcus
- baccili: bacillus, clostridium, corynebacterium, listeria
10
Q
How do you differentiate between the gram (+) cocci bacteria?
A
catalase test: (+) organisms produce H2O2 bubbles when exposed to H2O2 (catalase used as a defense mech in bacteria to H2O2 prod by macros/neutros)
- catalase (+): staphylococcus
- catalase (-): streptococcus/enterococcus
11
Q
How do you differentiate between the gram (+) bacilli bacteria?
A
- spore forming: bacillus (grows in oxygen, some species can be anaerobic), clostridium (strictly anaerobic)
- non-spore forming: corynebacterium (clubbed shape, non-motile), listeria (motile at 25 deg)
12
Q
What are the 3 principal staphylococcus species and how do you differentiate them?
A
- staphylococcus aureus (coagulase +)
- staphylococcus epidermis (coag -)
- staphylococcus saprophyticus (coag -)
13
Q
- produces golden yellow colonies
- gram positive cocci in clusters
- catalse positive (breaks down H2O2), coagulase positive (protective protein, activates fibrin clot)
- other protective proteins: hemolysins, leukocidins, penicillinase, protein A (prevents antibody mediated binding)
- tissue destroying proteins: hyaluronidase (CT destroying), staphylokinase (clot destroying), lipase (fat destroying)
A
staphylococcus aureus
14
Q
What diseases are caused by staphylococcus aureus direct invasion?
A
- superficial skin and underlying soft tissue infections (healthy individuals): folliculitis, impetigo, cellulitis, furuncles/carbuncles (abscesses), wound infections
- septic arthritis (young and elderly)
- severe necrotizing pneumonia (usually after previous infection such as virus)
- acute necrotizing endocarditis (IV drug abuser using dirty needles, usually infecting tricuspid valve)
(MRSA becoming a large tx problem especially in hospitals)
15
Q
What diseases are caused by staphylococcus aureus toxin?
A
- gastroenteritis: caused by preformed enterotoxin that contaminates food (wash hands); causes n/v/d/abd pain
- scalded skin syndrome: caused by exfoliative toxin A and B, children/infants, causes peeling of skin
- toxic shock syndrome: caused by TSST-1 toxin (superantigen) which causes release of TNF and IL-1; a/w use of superabsorbant tampon; general time line is 1. GI sx > 2. diffuse rash (palms/soles) > 3. shock, hypotension, death
*bonus: other dz’s w/ rash on palms soles are rocky mountain spotted fever and syphilis*
16
Q
- catalase positive, coagulase negative
- typically found in nml flora of skin
- virulence: biofilm (adheres to foreign device substrate creating scaffold for bacteria to exist and creates barrier to host immune system)
- nosocomial infection: infects prosthetic components (heart valves), hardware, catheters, shunts, etc
- causes subacute endocarditis (low grade fever)
- requires multiple positive blood cultures to dx as this bacteria frequently contaminates standard blood cultures
A
staphylococcus epidermidis
17
Q
- catalase positive, coagulase negative
- common cause of community aquired UTI’s
- frequent in sex active young women (short urethra), aka “honeymoon cystitis”
A
staphylococcus saprophyticus
18
Q
How do you differentiate between streptococcus/enterococcus species?
A
hemolysis
- β hemolysis: complete breakdown of blood (s. pyrogenes, s. agalactiae)
- α hemolysis: partial breakdown of blood (s. pneumoniae, viridans strep)
- γ hemolysis: no breakdown (enterococci (e. faecium, e. faecalis), nonenterococcus (s. bovis))
19
Q
- beta-hemolytic streptococcus
- group A strep b/c it is Bacitracin sensitive
- virulence factors: M protein (inhibits activation of complement), streptolysins (destroy RBCs)
- streptococcal pharyngitis: exudative, purulent infection of palatine tonsils/pharynx w/ high fever, lymphadenopathy; dx through rapid antigen test or culture (important to dx/tx due to risk of subsequent rheumatic fever or post-strep glomerulonephritis)
- causes slew of other dz’s
A
streptococcus pyogenes
20
Q
What diseases are caused by streptococcus pyogenes?
A
- streptococcal pharyngitis
- scarlet fever
- erysipelas
- necrotizing fasciitis
- impetigo/cellulitis
- rheumatic fever
- post-streptococcus glomerulonephritis
21
Q
- caused by strep pyogenes, due to pyrogenic (erythrogenic) exotoxin
- fever, erythematous rough “sandpaper” rash on trunk/neck but not face
- erythematous “strawberry” tongue
- seen in school aged children
A
scarlet fever
22
Q
- caused by strep pyogenes
- “sunburn” appearance on face
- warm to touch, sharp demarcation
- ages 60-80 high risk
- infection of upper dermis
A
erysipelas
23
Q
- caused by strep pyogenes
- rapidly progressing infection of fascia
- purplish discoloration, v painful
- aggressive surg intervention and antibiotics necessary to save tissue
A
necrotizing faciitis
24
Q
- caused by strep pyogenes and staph aureus
- golden crusted rash often in exposed surfaces including face
- often seen in children
A
impetigo
25
- caused by **strep pyogenes and staph aureus**
- non-necrotizing infection of skin and **subcutaneous tissues**
- often occurs after traumatic breach of skin
- **swollen, erythematous, warm**
Cellulitis
26
- caused by **strep pyogenes**
- multisystem inflammatory disorder following **group A streptococcus pharyngitis**
- caused by antibodies and CD4+ T cell rxn against **M streptococcal antigen** following strep pharyngitis
- signs/sx: fever (101+), migratory polyarthritis (large joints), pancarditis (pericarditis, mitral valvulitis), subcutaneous nodules, erythema marginatum, sydenham chorea
rheumatic fever
27
- caused by **strep pyogenes** following **group A step pharyngitis** or **skin infection**
- immune complex mediated: **antibody-antigen complex** (strep antigen) deposits in glomerular basement membrane
- presents (usually in children) w/ **edema, htn, hematuria, proteinuria**
- confirmatory test: **both this condition** and **rheumatic fever** by **detection of AB's** to **streptolysin O** and **DNase B**
post-streptococcal glomerulonephritis
28
- **beta-hemalytic** streptococcus, **group B** b/c it is insensitive to Bactracin
- colonizes vagina in 1/4 of pregnant women
- can result in **neonatal meningitis, pneumonia,** and **sepsis**; maternal sepsis can also occur
- antepartum screening during 3rd trimester
streptococcus agalactiae
\*bonus: other organisms that cause **neonatal meningitis**: listeria monocytogenes and E. coli\*
29
- **alpha-hemolytic encapsulated** strep, typically in diplococci or short chains
- colonizes nasopharynx
- **Quellung test (+)**: swollen capsule seen w/ addition of anti-capsular Ab's
- **Optochin sensitive**: lack of growth adjacent to antibiotic optochin on blood agar plate
- virulence factor: IgA protease
- vaccine available for children and adults
streptococcus pneumoniae
30
What diseases are caused by streptococcus pneumoniae?
- pneumococcal pneumonia
- meningitis
- otitis media
\*bonus: asplenic individuals are at increased risk for these dz's as they lack the splenic macrophages that remove encapsulated bacteria (strep pneu)\*
31
- caused by **strep pneumoniae**
- **MOST COMMON CAUSE OF COMMUNITY ACQUIRED PNEUMONIA**
- **lobar consolidative pattern** w/ **high fever**, chills, **cough, SOB**, chest pain
- frequently seen in **eldery (older than 65)**
- risk factors: COPD, smoking, previous flu infection, immunocompromised, asplenia
- CDC recs vaccine for adults 65+
pneumococcal pneumonia
32
- caused by **streptococcus pnemoniae (#1 cause of this condition in young children****)**
- classic triad: **high fever (100.4+), nuchal rigidity, abnml mental status change**
- others: HA, photophobia, n/v
- CSF w/ gram stain, culture, PCR to confirm
bacterial meningitis
33
- most common bacterial causes: **strep pneumoniae**, haemophilus influenzae, morazella catarrhalis
- **middle ear infection,** most often affects **young children**
- presentation: **ear pain, tugging/pulling ear,** hearing loss, drainage
otitis media
34
Why are asplenic/hyposplenic individuals more susceptible to certain bacterial infections?
- encapsulated bacteria are opsonized and cleared by spleen (splenic macrophages)
- top 3 bacteria: **strep pneumoniae, haemophilus influenzae (type B), neisseria meningitis**
- asplenia/hyposplenia can be caused by trauma, sickle cell anemia, lymphoma
35
- heterogeneous group of bacteria, typically **alpha-hemolytic** w/ greenish hemolysis
- aerobic to faculatatively anaerobic, unencapsulated
- diseases: **dental caries** (cavities) especially S. mutans; **subacute bacterial endocarditis** (low grade fever, fatigue); abscesses (brain, liver) caused by microaerophilic anginosus group
- endocarditis pathogenesis is similar to HACEK group \> following invasive **dental procedures** both **HACEK** and this group of bacteria can seed blood stream causing **subacute endocarditis**
streptococci viridans group
\*bonus: viridis means green in latin, remember verde for green in Spanish\*
36
- majority are **gamma-hemolytic**, however some are **alpha-hemolytic**, grows on **bile and 6.5% NaCl**
- nml bowel flora: E. faecalis, E. facium
- causes **nosocomial opportunistic infections**
- resistant to many drugs including vancomycin
- dz: wound infections, UTI's, biliary tract infections, subacute endocarditis
enterococci
37
- **gamma-hemolytic** bacteria, grow on **bile but not 6.5% NaCl**
- **strep bovis**: most important member, strongly a/w **colon cancer**
group D non-enterococci
38
- **gram positive, spore forming, aerobic rod**
- **spores are extremely heat resistant** (persist despite cooking), survive up to 212+
- **spores germinate, bacteria create toxin** in food, the heat stabile form is **not neutralized by reheating** (ex: reheated rice)
- **toxins**: **heat stabile toxin** (n/v/abd cramps, 1-3 hours), **heat labile toxin** (watery diarrhea, n/v/abd cramps, typically caused by **direct ingestion** of bacteria, 8 hours)
bacillus cereus
39
- **gram positive, encapsulated,** facultative anaerobic **spore forming rod**
- **spores** are **resistant to drying, heat, chemicals**
- found in **herbivore animals/products (hides)** and soil
- virulence factors: plasmid encoded (pX01, pX02)
- **cutaneous**: "malignant pustule", progresses to systemic signs within 20% of infections, highly treatable
- **inhalation**: **pulmonary spores** \> mediastinal lymph nodes \> germinate \> **mediastinal hemorrhage** \> **death** **(agent of bioterrorism)**
- GI (spores directly ingested) and injection (IV drug) are more rare
bacillus anthracis
40
- causative organism of **antibiotic associated colitis** (clindamycin, penicillins, cephalosporins)
- fecal-oral route via injestion of spores; problem in hospitals/nursing homes
- virulence: **toxin A** (increases inflammation and fluid secretion (diarrhea)), **toxin B** (cytotoxic to colonic epithelial cells)
- sx: diarrhea, abd pain, fever
- path finding: **pseudomenbranous colitis**
- detected: NAT or toxins in stool
clostridium difficile
41
- toxin: neurotoxin in bacteria that **inhibits** release of **acetylcholine** at **neuromuscular junction**
- adult food born: undercooked food allows spore survival \> growth of bacteria w/ neurotoxin
- typical in **canned food**, smoked fish, **honey**
- sx: **bilat cranial neuropathies** (vision changes, droop eyelids, facial weakness), a/w **symmetric descending muscle weakness** \> **resp paralysis \> death**
- infantile: consumption of spores from **honey** or infant powder \> **constipation** \> **difficult swallowing, muscle weakness** \> **resp failure**
clostridium botulinum
42
- anaerobic spore-forming bacteria found in soil, a/w **deep puncture wounds**
- **neurotoxin inactivates glycine** and **GABA** leading to **sustained contraction of motor neurons**
- sx: **severe muscle spasms**, **autonomic instability**, risus sardonicus, lockjaw, opisthotonos
- vaccine available (TDAP), starts in infancy w/ booster for adults
clostridium tetani
43
- anaerobic spores found in soil can contaminate **deep wounds/trauma**
- virulence: alpha toxin (lecithinase) lyses RBCs and endothelial cells \> **hemolysis and hemorrhage**
- sx: **cellulitis/wound infections** can progress to **myonecrosis**; severe pain, edema, dark purple to black skin discoloration w/ **gas formation (gas gangrene CO2 prod**, bullae); **crepitus**
- food poisoning more rare: diarrhea, abd cramps, rarely necrotizing enteritis
clostridium perfringens
\*remember as **gas gangrene** seen in WWI and WWII\*
44
- **gram positive, pleomorphic, club shaped** bacteria that is non-spore forming
- cultured on specialized media (tellurite agar and Loeffler's medium)
- virulence: phage encoded **AB exotoxin** (inactivates EF2 preventing mRNA translation)
- nonspecific sx: fever, HA, malaise, cough, adenopathy, **pharyngitis w/ gray pseudomembrane formation** (**do not scrape** as this can release more AB toxin)
- systemic AB toxin effects: **myocarditis** (dysrhythmias, AV conduction block), **neural involvement** (cranial/peripheral palsies)
- vaccine: TDAP
corynebacterium diphtheriae
45
- **gram positive**, partially acid fast pleomorphic, **clubbed rod**, facultative intracellular bacteria
- found in mammals, manure, soil
- pathogen of **immunocompromised**, causes **pulm dz** (pneum, lung nodules/abscesses)
- clinical findings: upper lung nodules and **cavities w/ air-fluid levels**
rhodococcus equi
| (formerly corynebacterium equi)
46
- **gram positive**, anaerobic, intracellular facultative anaerobic rod
- grows at **cooler temps** (39-50), flagella growth w tumbling motility at 77
- virulence: listeriolysin O (macrophage phagolysosome escape)
- found in contaminated **dairy prods**, **meat**, sprouts
- **pregnant women advised to avoid products due to risk of baby infection**
- in immunocompetent: mild influenza illness
- **fetus and neonate**: 1) **granulomatous infantiseptica** (widespread granulomas, often fatal, obtained transplacentally), 2) **neonatal meningitis** (w/ septicemia via fecal contamination occurs later 2-3 weeks after birth)
- **pregnant women**: predisposed to **sepsis**
- older adults/immunocompromised: most common cause of meningitis in transplant patients and those on corticosteroids
listeria monocytogenes
47
What are the 3 gram (-) diplococci bacteria?
1. neisseria meningitis
2. neisseria gonorrhea
3. moraxella catarrhalis
48
- facultative anaerobic, **intracellular gram negative diplococci**
- grows on **"chocolate agar"** (heated blood agar), specifically **Thayer-Martin agar** (VCN antibiotic modified), will also grow on standard blood agar
- colonizes nasopharynx
- virulence: capsule, IgA1 protease, pili (adherence), **LPS (endotoxin)**
- susceptible populations: **neonates, military recruits, college students, asplenia**
- vaccines: MenACWY for preteens/teens and MenB for 16-18 y/o in high risk groups (B serotypes)
neisseria meningitis
49
What diseases are caused by neisseria meningitis?
- meningitis: **fever, stiff neck, n/v, rash**, infants may lack classic sx (only fever)
- meningococcemia: meningitis + septicemia; **Waterhouse-Friderichsen syndrome** (bilateral adrenal hemorrhage w/ insufficiency, severe hypotension, disseminated intravascular thrombosis, death)
50
- facultative anaerobic and facultative **intracellular gram negative diplococci**
- grows on Thayer-Martin (VCN) chocolate agar
- second most common bacterial STD
- virulence factors: IgA1 protease, pili (adherence), opa proteins (adhere/prevent immune response)
neisseria gonorrhoeae
51
What diseases are caused by neisseria gonorrhoeae?
- **men**: urethritis (discharge, dysuria), acute epididymitis (posterior testicular pain, swelling)
- **women**: urethritis (usually asx, sx dysuria), cervicitis (usually asx, sx itching and discharge), PID (infection of uterus/fallopian tubes, ovaries, can cause sterility), perihepatitis (Fitz-Hugh-Curits syndrome): inflammation of liver capsule \> sharp RUQ pleuritic pain
- both: disseminated gonococcal infection \> septic arthritis
- **infants: ophthalmia neonatorum** \> neonatal conjunctivitis
52
- **gram negative** aerobic **diplococcus**
- can form part of nml resp flora
- can culture on routine blood agar and **chocolate agar**
- can cause bronchopneumonia in elderly
- 3rd most common cause of **otitis media** in children
moraxella catarrhalis
53
What bacteria comprise the gram negative enterics?
- enterobacteriaceae
- pseudomonadaceae (pseudomonas aeruginosa)
- bacteriodaceae
- vibrionaceae (vibrio species, campylobacter, helicobacter)
54
What are the different types of bacteria that cause diarrhea and how do the presenting symptoms differ?
1. lack of invasion \> **watery diarrhea**: enterotoxigenic E. coli, vibrio cholera
2. intestinal epithelium invasion/death \> **fever, bloody diarrhea, abd cramps**: enterohemorrhagic and enteroinvasive E. coli, shigella
3. invasion into lymph and blood \> **fever, diarrhea +/- blood, abd pain \> sepsis, bacteremia**: salmonella typhi, yersinia enterocolitica, campylobacter jejuni
55
What enterobacteriaceae cause GI dz and which cause nosocomial infections?
- **GI dz**: **E. coli** (diarrhea, meningitis (neonatal), pneumonia, UTI), **shigella** (diarrhea), **salmonella** (typhi causes thyphoid fever, non-typhi causes gastroenteritis, osteomyelitis), **yersinia enterocolitica** (diarrhea, acute enterocolitis)
- **nosocomial infections**: **proteus mirabilis** (UTI), **klebsiella pneumoniae** (pneumonia), **enterobacter & serratia** (various including pneumonia, UTI, wound)
\*overlap: aka E. coli can cause nosocomial infections as well\*
56
What is unique to E. coli and most of the nosocomial enterobacteriaceae in terms of culturing?
**lactose fermenters**: E. coli and many nosocomial enterobacteriaceae (klebsiella, enterobacter, citrobacter, serratia)
- **MacConkey agar**: show color change to **pink** w/ decreased pH
- **Eosin Methylene Blue (EMB)**: show color change to **black w/ metallic sheen**
57
- **gram negative rod, lactose fermenter, nml flora** of GI tract
- acquires virulence factors through plasmid exchange and bacteriophages
- dz and subtype depends on virulence factors
- has pili which allows adherence to host cells
- dz's: **diarrhea, meningitis (esp neonatal), UTI (most common cause)**, pneumonia
escherichia coli
58
What diseases are caused by E. coli?
- **enterotoxigenic E. coli (ETEC)**: consumption of **fecally contaminated food or water**, seen in developing countries w/ poor sanitation, **heat labile (LT)** which is cholera like and **heat stabile (ST) toxins**, **watery diarrhea** and abd cramps, most common cause of traveler's diarrhea
- **enteroinvasive E. coli (EIEC)**: invasive plasmid (same as Shigella), invasion causes fever and **bloody diarrhea**
- **enterohemorrhagic E. coli (EHEC)**: produces **Shigella-like toxin** 1 or 2 (Stx1 or Stx2) which causes cell death, hemorrhagic colitis (bloody diarrhea, abd cramps)
- hemolytic uremic syndrome (HUS): caused by **EHEC E. coli 0157; anemia, thrombocytopenia, renal damage/failure (uremia)**; caused by Stx2
- **meningitis**: most common cause of **neonatal meningitis**
- **UTI**: most common cause of **UTI**, typically in women, can cause nosocomial infections w/ indwelling catheters
- pneumonia: hospital acquired, can occasionally progress to sepsis
\*bonus: neonatal meningitis: strep agalactiae (group B), listeria monocytogenes, E. coli\*
59
- **gram negative rod**, non-motile, **always pathogenic**
- outbreaks in preschool daycare centers, nursing homes, fecal-oral transmission
- **invades intestine** prod **high fever** and **bloody diarrhea**, abd cramps
- four species: S. sonnei, S. dysenteriae, S. flexneri, S. boydii
- S. sonnei most common in US
- **S. dysenteriae** prod **Shiga toxin** results in cell death (inhibits 60S ribosomal subunit) and causes more severe dz
Shigella
60
- **gram negative rod**, motile, encapsulated (Vi antigen), produces H2S
- **pathogenic**, fecal-oral transmission
- unwashed, **contaminated food** (**chicken, eggs, spinach,** fruit)
- **S. typhi**: humans only, can develop **chronic carriage in gallbladder**, a/w **gallbladder adenocarcinoma**
- **non-typhoidal: zoonotic reservoir in virtually any animal**
Salmonella
61
What disease is caused by salmonella typhi?
- typhoid fever
- S. paratyphi can cause similar dz, but typically milder
- invasion through intestina \> macrophages \> liver, spleen
- 7-14 day incubation period
- **stepwise fever** (rises during day, drops each morning)
- **diffuse/colicky RUQ abd pain**
- HA, malaise, hepatosplenomegaly
- **delirium, typhoid enchephalopathy, fever peaks (104 F)**
- **rose spots = bacterial emboli**
- toxemia can lead to death
- can have chronic carrier state (infectious) = Typhoid Mary
62
What diseases are caused by salmonella?
- typhoid fever (S. typhi)
- sepsis/bacteremia: localized infection of bone, brain, lung; S. paratyphi, S. choleraesuis, S. typhi; asplenic/hyposplenic patients increased risk for sepsi \> sickle cell anemia a/w osteomyelitis
- **gastroenteritis/diarrhea**: caused by **non-typhoidal salmonella species**, **n/v/watery diarrhea (+/- blood)**, **fever** occurs in 1/2
63
- **gram negative rod**, bipolar staining, motile
- zoonotic reservoir (widespread in mammals)
- infection from contaminated water/food, **esp milk products**
- presents w/ **fever, abd pain, diarrhea**
- can show RLQ pain, acute appendicitis mimic "**pseudoappendicitis**" = ileitis and mesenteric lymphadenitis
yersinia enterocolitica
64
- gram negative rod, **motile (swarming concentric growth pattern), urease positive**
- urease breaks down urea to CO2 and ammonia - ammonia causes urine to become alkaline
- certain antigens (OX-19, OX-2, OX-K) show cross reactivity w/ Rickettsia, basis of Weil Felix test
- common cause of **UTI, esp in nosocomial setting**
proteus mirabilis
\*bonus: E. coli is most common cause of UTI's in nosocomial setting, however proteus mirabilis should still be considered\*
65
- **gram negative rod, encapsulated** (O antigen), non-motile
- common cause of infections inf **alcoholics** and **hospital patients**
- causes **pneumonia (necrotizing, cavitary),** UTI's (esp catheterized)
- classically, pneumonia is necrotizing w/ **"currant jelly" sputum**
- high mortality rate
klebsiella pneumoniae
66
- nosocomial disease causing enterobacteriaceae
- opportunistic esp in immunocompromised
- both cause pneumonia, UTI's, wound infections
- both ubiquitous in environment
- enterobacter: highly motile and known for its antibiotic resistance (ampicillin and cephalosporins)
- serratia: characteristic red pigment
\*card is more for boards than MOD\*
67
- most important dz causing member of pseudomonadaceae
- **gram negative rod, aerobic**, motile (flagellated), polysaccharide capsule (some strains)
- multiple virulence factors: hemolysin, collagenase, elastase, fibrinolysin, phospholipase C, Dnase)
- produces **green-blue pigments**: procyanin (blue) and pyoverdin (green)
- has **distinctive grape-like scrent**
pseudomonas aeruginosa
68
What diseases does pseudomonas aeruginosa cause?
- causes dz in: **cystic fibrosis pt's, burn victims, severely debilitated hospital pt's**, diabetics (osteomyelitis), swimmers (otitis externa)
- **pulmonary infections** **(mild bronchitis to pneumonia)**: esp in **CF** and hospital pt's
- **primary skin/wound infections**: esp in **burn victims**, **otitis externa** (swimmer's ear), and **hot tub folliculitis**
- infections esp from lines/catheters can evolve to bacteremia
69
- **gram negative bacillus, obligate anaerobe**
- comprises 99% of nml gut flora, another species (B. melaninogenicus) is also in mouth/vagina
- causes abscess after **traumatic bowel injury** and **ischemic bowel perforation**, and **deep abscesses** (surg sites abd/gyn)
bacteroides fragilis
\*side note: B. melaninogenicus causes necrotizing pneumonia after aspiration and periodontal disease\*
70
- **gram negative comma shaped bacteria**, motile w/ single flagellum (H antigen); non-invasive, nut attaches via fimbriae
- fecal-oral transmission, in **brackish** **and marine waters**
- **toxin: activates cAMP \>** active secretion of NaCl, bicarb, K+ into lumen, **osmotic pull of water** (same mech as enterotoxogenic E. coli)
- result: abrupt onset of **profuse watery diarrhea** \> up to 1L of fluid/hour, dehydration can result in death, common in poor countries
vibrio cholerae
71
- **consumption of raw seafood**, esp oysters/sushi
- gastroenteritis, **watery diarrhea, n/v**
- most common cause of food poisoning in Japan
vibrio parahaemolyticus
72
- **consumption of raw seafood**, esp oysters
- can also be transmitted through direct handling of fish/oysters
- **consumption** \> severe dz (**septicemia** w/ sudden **fever**, chills, **hypotension**, n/v, diarrhea)
- **direct handling** \> rapidly **progressive wound infection**
- can be deadly w/ high mortality rate
vibrio vulnificus
73
- gram negative **comma shaped rod,** motile (single flagellum), microaerophilic
- zoonotic; **uncooked meat (chicken), unpasteurized milk**
- **invades mucosa (small bowel and colon)**, w/ mucosal ulceration: **fever, diarrhea (+/- blood), severe abd pain, can mimic acute apendicitis**
- can trigger dz of immune by cross reactivity to self: **Guillain-Barre syndrome** (immune mediated neuropathy causing ascending flaccid paralysis)
campylobacter jejuni
\*bonus: other bacteria, yersinia enterocolitica, also mimics case of acute apendicitis\*
74
- a post infectious immune mediated reaction a/w **HLA-B27**
- **classic triad: conjunctivitis, urethritis, arthritis**
- can be triggered by many of the **enteric bacteria**: salmonella, shigella, campylobacter jejuni, yersinia enterocolitica, clostridium difficile; and also chlamydia trachomatis
Reiter's syndrome
(reactive arthritis)
"can't see, can't pee, can't climb a tree"
75
- **gram negative curvilinear rod** (spirilla), motile w/ single flagellum, microaerophilic, **urease positive** (raises epigastric pH)
- dz: **chronic gastritis** (n/v), **gastric/duodenal ulcers** (pain)
- long term risks: **gastric B-cell lymphome** (MALT lymphoma), **gastric adenocarcinoma**
- difficult to see on gram stain, silver stain usually used on bx
helicobacter pylori
76
What 3 gram negative enteric bacteria can cause respiratory disease?
- bordetella pertussis
- legionella pneumophilia
- haemophilus influenzae
77
- **gram negative rod**, aerobic, highly contagious, human resp pathogen
- virulence factors: **pertussis toxin** (**increases cAMP \>** increases histamine effects; decreases phagocytosis \> **lymphocytosis**), adenylate cyclase toxin (inhibits leukocyte chemotaxis, phagocytosis), hemagglutinin (mediates attachment), trachel cytotoxin (paralyzes/kills ciliated epithelial cells)
- resp pathogen: causes cold (rhinorrhea, sneezing, malaise, low fever); after 1-2 weeks results in **whooping cough**, can progress to pneumonia
- **vaccine**: TDAP
bordetella pertussis
\*bonus: the fact that B. pertussis causes **lymphocytosis** is unique, as bacterial infections generally cause neutrophilia, while viral infections generally cause lymphocytosis\*
78
- **gram negative rod**, aerobic, facultative intracellular organism (survives in macrophages)
- aerosolized bacteria causes infection: **found in water systems** (cooling towers, condensers, showers/tubs)
- can live inside free living **amoebas (reservoir)** and in **biofilms**
- **pontiac fever**: **self-limited febrile illness (2-5 days)** w/ fever, chills, myalgia, malaise, HA
- **Legionnaires' dz:** **more severe, multilobular pneumonia w/ abscess**, fever, chills, cough, can lead to multiorgan failure and death (15%)
legionella pneumophilia
\*remember American Legion and to drink lemonchellas b/c stagnant waterrrrrr has bacteria\*
79
- gram negative, **pleomorphic rod** or coccobacillus; resp pathogen
- **all species within this category require hemin and NAD (X and V factors)**, both found in **blood**
- consists of both capsulated and non-encapsulated (non-typeable) strains
- **encapsulated**: has higher virulence, polysaccharide capsule protects against phagocytosis
- **Hib vaccine**: given during first 1.5 years of life, protects against type B which causes early childhood meningitis
haemophilus influenzae
\*can be grown on heat lysed blood agar or chocolate agar like Neisseria species and Moraxella catarrhalis, however H. influenzae will NOT grow on routine blood agar as it does not contain X and V factors\*
80
What diseases are caused by haemophilus influenzae?
- **encapsulated (typeable)****, including Hib**:**early childhood meningitis**,**acute epiglottis**(fever, sore throat \> severe**wheezing, drooling**, exam can induce laryngeal spasm), septic arthritis (young child, monoarticular), sepsis
- dz manifestations occur at 6 months to 3 years after disappearance of maternal Ab's
- **unencapsulated (non-typeable**): COPD exacerbations, sinusitis, **otitis media**
81
- **gram negative coccobacillus, X and V factors** req for growth
- STD: causes **painful genital ulcer "chancroid"**
- can cause **painful** unilat suppurative (pus forming) inguinal **lymphadenopathy**
- rare in US, endemic in Asia, Africa, and Caribbean
- differential: herpes, syphilis, granuloma inguinale, lymphogranuloma venerum
haemophilus ducreyi
"remember school of fish on gram stain\*
82
**chancroid**
- organism:
- typical lesion:
- in US: uncommon
- region lymph nodes: **painful suppurative lymphadenopathy**
**chancroid**
- organism: haemophilus ducreyi
- typical lesion: **painful** papule \> ulcer
- in US: uncommon
- region lymph nodes: **painful suppurative lymphadenopathy**
83
**herpes simplex**
- organism:
- typical lesion:
- in US: **common**
- region lymph nodes: **painful lymphadenopathy**
**herpes simplex**
- organism: HSVI and II virus
- typical lesion: **painful** blister \> ulcer
- in US: **common**
- region lymph nodes: **painful lymphadenopathy**
84
**primary syphilis**
- organism:
- typical lesion:
- in US: **common**
- region lymph nodes: not in primary dz
**primary syphilis**
- organism: treponema pallidum
- typical lesion: **painless** ulcer
- in US: **common**
- region lymph nodes: not in primary dz
85
**lymphogranuloma venerum**
- organism:
- typical lesion:
- in US: uncommon
- region lymph nodes: **painful suppurative lymphadenopathy**
**lymphogranuloma venerum**
- organism: chlamydia trachomatis
- typical lesion: **painless** papula \> can ulcerate
- in US: uncommon
- region lymph nodes: **painful suppurative lymphadenopathy**
86
- gram negative to variable rod (thin cell wall)
- cause of **bacterial vaginitis**
- typically detected on **pap smear** as "clue cells"
- **replaces nml vag flora**, results in: **malodorous "fishy smelling" discharge, puritus, and dysuria**
gardnerella vaginalis
87
What types of dz's do the gram negative zoonotic bacilli bacteria cause?
- **yersinia pestis, francisella tularensis, and brucella species**: virulent facultative intracellular organisms (survive within macros, can be transferred to lymph and disseminate)
- **pasteurella multocida**: localized infection, not intracellular
88
- gram negative zoonotic rod, **bipolar shape**, has killed millions throughout history
- reservoir: found in wild rodents, **prairie dogs,** transferred to rats during epidemics
- vector: **fleas**
- **bubonic plague**: local flea bite \> bacteria invades skin, hemorrhage under skin causes "black death" \> lymph nodes becomes hot painful "buboes" w/ fever and HA \> dissemination and death (75%)
- **pneumonic plague**: aerosolized human to human contact
yersinia pestis
\*remember "pests" spread the plague (fleas/rodents), however we have put a "safety pin" in the severity of dz w/ modern tx\*
\*potential agent of bioterrorism\*
89
- **gram negative zoonotic rod**
- in many wild animals, most commonly obtained by handling **rabits** or via **tick/deerfly bite**
- ulceroglandular tularemia: **similar pres to bubonic plague except** presents w/ **skin ulcer** (occurs at site of bite)
- pneumotic tularemia: aerosolization of dz (skinning, taxidermy), severe atypical pneumonia
francisella tularensis
\*potential agent of bioterrorism\*
90
- **gram negative zoonotic rod**
- cause: **domesticated animal prod**, drinking **unpasteurized milk**, contact w/ infected **meat/placenta**
- sx: **fever,** HA, **night sweats**, joint/muscle pain, lymphadenopathy, splenomegaly
- **undulant fever characteristic**
- hematologic abnormalities can occur: **anemia and leukopenia**
brucella species
\*remember undulant fever\*
91
- **gram negative zoonotic rod**, not intracellular
- nml flora of **cats and dogs**, often results after **bite/scratch**
- **facultative anaerobe**: can cause localized **wound infection (cellulitis)**
pasteurella multocida
\*remember kitty scratch\*
92
- gram negative rod
- **"cat scratch disease"**
- transmitted by cat **scratch/bite**
- **regional low grade fever, malaise, lymphadenopathy**
- **self limiting**
- dx on biopsy (silver stain), difficult to culture
- can cause **bacillary angiomatosis** (along w/ B. quintana/trench fever): vascular proliferative dz consisting of numerous small vascular lesions which occur in immunocompromised
bartonella henselae
\*remember cat scratch disease\*
93
What are the obligate intracellular gram negative bacteria?
- **chlamydia species**: C. trachomatis (STD), C. pneumoniae and C. psittaci (atypical pneumonia)
- **rickettsia species**: rickettsia rickettsia causes Rocky Mountain Spotted fever (fever, rash, thrombocytopenia)
- **coxiella burnetti (Q fever)**: fever, HA, atypical pneumonia
- **ehrlichia chaffeensis**: similar to RMSF except no rash
94
- gram negative, tiny **obligate intracellular bacteria**
- extremely small organism, on the order of viruses
- predilection to mucosal epithelial cells (squamous, columnar)
- elementary body: extracellular infectious particle
- penetrates cell and replicates in endosome
- reticulate body: mature intracellular form, steals energy from host via ATP/ADP translocase
chlamydia species
95
- **most common bacterial sexually transmitted infection**, exclusively a human pathogen
- very common cause of **neonatal blindness** worldwide
- transmission through direct contact, common serotypes cause urogenital dz are D-K
- approx 3/4 of women and 1/2 of men are asymptomatic
- causes: **non-gonococcal urethritis** (dysuria/discharge in men, dysuria/inc freq in women)
- men: occasionally causes **epididymitis**
- women: **mucopurulent cervicitis \> ascending infection \> PID** (risk for scarrring, ectopic preg, and **infertility**)
chlamydia trachomatis
96
What other diseases can be caused by chlamydia trachomatis?
- **trachoma** (serotypes A-C): **chronic eye infection**, problem in developing countries, spread by flies/indirect contact, **leading cause of blindness worldwide**
- **neonatal inclusion conjunctivitis** (serotypes D-K): presents like gonococcal ophthalmia neonatorum, can cause infant pneumonia
- **perihepatitis (Fritz-Hugh-Curtis syndrome)**: inflammation of liver capsule resulting from PID
- **lymphogranuloma venereum**: caused by **L serotypes (L1, L2, L3)**, painless lesion that can ulcerate, tender/suppurative lymphadenitis
- also a/w Reiter's syndrome
97
What type of lung disease can be caused by chlamydia species?
- **mild atypical pneumonia**: dry cough, low grade fever w/ patchy interstitial inflammatory changes
- the two agents: chlamydia pneumonia (community acq direct spread) and **chlamydia psittaci "psittacosis" (atypical pneumonia transmitted from bird exposure**, aka pet markers, aviary, etc)
98
- **gram negative** pleomorphic **coccobacillus** form
- **obligate intracellular parasite**, has ability to steal ATP like Chlamydia
- transmitted by arthropod vectors
- most species are **Weil-Felix test positive** (show agglutination by OX antibodies (as does Proteus)) w/ the exception of R. akari
- present w/ **fever,** HA, **rash, thrombocytopenia**
rickettsia species
99
- the cause of **Rocky Mountain spotted fever**
- causes: **fever, centripetal rash** on the **palms/soles, thrombocytopenia**, HA
- vector: dermacentor ticks
- OX-19, OX-2 positive (Weil-Felix positive)
- prevalent in **central, southeast US**
rickettsia rickettsii
100
- cause of **rickettsialpox**
- prominent **blister/eschar** at bite site, fever, generalized rash, **self-limiting**
- vector: **mite**
- OX negative (**Weil-Felix negative**)
rickettsia akari
101
- causes high fever, HA, maculopapular rash +/- eschar
- vector: **mite**
- OX-K (Weil-Felix positive)
- **southeastern Asia, Pacific**
rickettsia tsutsugamushi
102
- causes **epidemic typhus**
- HA, fever, rash
- vector: **louse**
- OX-19 (Weil-Felix positive)
- **unsanitary, crowded conditions** (Napoleonic war)
- carried in **flying squirrels**, southern US
rickettsia prowazekii
103
- cause of **murine endemic typhus**
- HA, fever, truncal maculopapular rash
- vector: **flea**
- OX-19 (Weil-Felix positive)
- worldwide
- **"scrub typhus"**: seen in US soldiers during Vietnam and WWII
rickettsia typhi
104
- **obligate intracellular gram negative bacteria**
- **causes Q fever**
- extracellular **spore** phase (endospore)
- found in **cattle, sheep, goats**
airborne transmission from spore contaminated **hide and birth products**
- **fever, atypical pneumonia,** HA
coxiella burnetti
\*remember Q fever\*
105
- **intracellular tick borne illness**
- similar to RMSF but typically **no rash**
- fever, HA, malaise
- transmitted by ticks in **southeast and central US**
ehrlichia chaffeensis
106
What are the different types of gram negative spirochete bacteria and their defining characteristics?
- **gram negative, corkscrew, spinning motility, difficult to culture**
- dx by darkfield microscopy, silver stains, and serologic testing
- **treponema species**: T. pallidum (syphilis, STD), T. pallidum subspecies (skin ulcers, gummas)
- **borrelia species**: B. burgdorferi (Lyme dz), B. recurrentis (relapsing fever)
- **leptospira species**: systemic dz
107
What are the characteristics of primary syphilis infection by treponema pallidum?
- **painless chancre** develops after 3-6 weeks of contact
- typically in genital region
108
What are the characteristics of secondary syphilis by treponema pallidum?
- develops **6 weeks** after primary infection
- **condyloma lata** (wart-like papular lesion), macular **rash** of **palms/soles**, patchy hair loss, lymphadenopathy, organ involvement (more so in tertiary)
\*remember other bacteria that cause involve palms/soles: RMSF (rickettsia rickettsii) and TSS (staph aureus)\*
109
What are the characteristics of tertiary syphilis by treponema pallidum?
- develops **6-40 years** after secondary infection
- **gummatous lesions** (skin and bone lesions comprised of spirochetal organisms in a marked plasma cell rich infiltrate), cardiovascular (**thoracic aortic aneurysm**, vasa vasorum destruction), **neurosyphilis** (asx, subacute **meningitis**, meningovascular syphilis, **tabes dorsalis**)
- **tabes dorsalis**: involves posterior columns of SC resulting in decreased coordination, loss of pain/temp, diminished proprioceptive/vibratory sense
- **Argyll Robinson pupils**: syphilitic lesion involving midbrain, pupil constrict to focus on near object but do not react to light
110
What are the characteristics of congenital syphilis?
- treponema pallidum crosses placental barrier (4th month of pregnancy)
- occurs within **2 years of birth**, often present w/ **mucous membrane** involvement (**rhinitis**) within weeks of life = **"snuffles"**
- develop manifestations of **secondary syphilis (rash of palms/soles)**, condyloma lata, high mortality
- **late congenital syphilis**: **\>2 years after birth**, findings of **tertiary syphilis** (CV typically spared), **neurosyphilis** (8th nerve involvement = deafness), **bone/teeth** involvement (Hutchinson's teeth and Saber shins)
111
How is syphilis diagnosed?
- primary and secondary active: dark-field microscopy of chancre, rash, condyloma latum
- **screening tests** (nonspecific): **VDRL** (venereal disease research lab), **RPR** (rapid plasma reagin)
- **diagnostic tests** (specific): **FTA-ABS** (indirect immunofluorescent treponemal antibody-absorption), PCR
112
What are the characteristics of treponema pallidum subspecies?
- endemicum and pertenue: skin ulcers and gummas
- carateum: skin discoloration
- **endemicum**: endemic syphilis, Bejel, Africa and Middle East; spread by sharing utensils; oral and skin lesions
- **pertenue**: Yaws; humid tropical climate; ulcer; direct skin contact, spread throughout community
- **carateum**: skin dz, rural Latin America; direct contact, discoloration of skin
113
- **spirochete** causing localized to systemic dz
- vector: **Ixodes tick (blacklegged ticks)**
- reservoir: **deer**, mice
- present: **northeast US, upper midwest, #1 tickborne illness**
- dx: typically made by combining clinical hx and either antibody test (ELISA or Western blot) or PCR test
borrelia burgforferi
| (Lyme disease)
114
What disease does borrelia burgdorferi cause?
- **Lyme disease**
- disease stages similar to syphilis
- **early localized dz**: 10 days after tick bite, **erythema migrans (at bite site)**, flu-like illness
- **early disseminated dz**: can involve **nervous system** (neuropathy, Bell's palsy, meningitis, **heart** (carditis, AV heart block), and **joints** (esp knee's)
- **late dz**: **chronic arthritis**, **encephalopathy** (memory impairment, somnolence)
\*remember: RMSF is another tick borne illness to know about\*
115
- causes **relapsing fever**
- **Western US**
- high fever, chills, HA's, myalgia, +/- rash
- **sx resolve**, then can **relapse 8 days later** due to rapid antigenic variation
borrelia recurrentis
116
- spirochete in **urine** of animals worldwide, fresh water contamination
- 2 phases: 1) high fever, HA, myalgia, red conjunctiva, photophobia; 2) after 1 week w/o sx, immune phase (due to host IgM antibody response) = meningeal sx
- Weil dz: severe systemic dz w/ renal, hepatic failure, multi-organ hemorrhage (damage to vessels)
leptospira interrogans
117
What are the characteristics and organisms within the mycobacterium group?
- **acid fast bacilli**, waxy cell wall w/ mycolic acids which retains stains after tx w/ acid or alcohol
- M. tuberculosis, M. leprae, M. avium complex (MAC)
118
What are the epidemiological facts regarding TB?
- \> 1 million deaths worldwide, person to person resp spread
- affects immunocompromised, esp HIV patients (approx 1/3 of HIV patients have TB)
- major countries: India, China, SE Asia, Africa
119
What is the host immune response to mycobacterium infection?
- mycobacterial organisms are taken up by alveolar macrophages
- **cell mediated immunity** response results in **necrotizing granulomata**
- seen in **both TB and leprosy**
- mycosides act as virulence factors: cord factor (increases TNF), sulfatides (allow initial survival in macrophages)
120
What are the characteristics of a primary tuberculosis infection?
- **primary TB**: **aerosolized transmission**, primary infection **begins in lungs**
- **primary symptomatic TB**: **immunocompromised, elderly, and young** at risk, **fever, chest pain, hilar lymphadenopathy**, effusion
- primary TB can wall off w/ Ghon complex: primary subpleural TB and regional lymphadenopathy, these areas (subpleural focus and lymph nodes) show **necrotizing granulomas**; rarely, primary progressive TB w/ dissemination
121
What are the characteristics of a secondary TB infection?
- disease that arises in a previously infected host, often through reactivation of latent infection
- typically appears **months to years** after primary infection
- insidious onset: **low grade fever, night sweats, hemoptysis**
- classicaly involves apex of **upper lobes** of one or both lungs \> can lead to a poorly walled cavitary lesion
- can **disseminate** through arteries causing **miliary TB** (innumerable lesions throughout organs)
- **any organ can be involved**: liver, spleen, bones (if **vertebral involvement** = **Pott's dz**), meninges, kidney, adrenals, etc
122
How is tuberculosis diagnosed?
- screening: **tuberculin skin test and interferon-gamma release assays** (purified protein antigen placed in dermis or blood, if TB exposure then immune rxn (unduration or IFN-gamma))
- suspected TB: chest x-ray (**primary** will show Ghon complex in middle/lower lobes and LN's; **secondary active** will show upper lobes, apices)
- sputum acid-fast stain and culture
- rapid molecular testing (sputum)
123
- cause of leprosy (Hansen's disease)
- low transmissibility, need prolonged close contact
- prevalent in certain developing countries (India, Brazil, Indonesia), occasionally seen in US (Louisiana, Texas, Cali)
- carried in **armadilos** in **southern US** (reservoir)
- **grows at cooler temps** \> preferentially starts by affecting the **skin**
mycobacterium leprae
124
What are the differences between tuberculoid leprosy and lepromatous leprosy?
- **severity is dependent on degree of cell mediated immunity**
- **tuberculoid leprosy: strong cell mediated response (Th1, IFN-gamma), localized skin lesions, granulomatous inflammation,** typically involves **unilat skin/nerve (loss of nerve sensation)**
- **lepromatous leprosy**: defective T cells, **no/minimal cell mediated response**, sparse lymphocytic response, **disseminated dz (skin lesions cover the body)**, **involvement of organs**
125
- found environmentally, esp in municipal water sources
- typically cause **low grade** nonspecific **atypical pneumonia**: **cough, fatigue, malaise**, +/- dyspnea, chest discomfort (low grade fever occasional)
- very common **opportunistic infection in HIV** patients w/ **CD4 T cell count \<50** = **unexplained weight loss, fever, diarrhea**
mycobacterium avium complex
126
What bacteria do not have cell walls?
- mycoplasma pneumoniae
- mycoplasma genitalium
- ureaplasma urealyticum
127
- **smallest bacteria, no cell walls**
- **"walking pneumonia"**: **mild, self limited bronchitis and pneumonia** (fever, sore throat, persistent dry cough)
- **very common cause of atypical pneumoia** in teenagers and young adults
- diagnostic tests: **cold agglutins (nonspecific)**, complement fixation, sputum culture (in sterol rich media), PCR
- a/w **erythema multiforme**: **multiple target lesions** spread from hands to trunk due to immune rxn (typically resolve in 2-3 weeks)
mycoplasma pneumoniae
128
What diseases do mycoplasma genitalium and ureaplasma urealyticum cause?
- **mycoplasma genitalium**: non-gonococcal **urethritis** (dysuria, discharge); **women** (**cervicitis** and associated PID), dx w/ PCR test
- **ureaplasma urealyticum**: can cause non-gonococcal **urethritis**, can be part of female vag flora (sex active), dx w/ PCR test
