Bacteria Flashcards
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
Q
- 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
A
Cellulitis
26
Q
- 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
A
rheumatic fever
27
Q
- 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
A
post-streptococcal glomerulonephritis
28
Q
- 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
A
streptococcus agalactiae
*bonus: other organisms that cause neonatal meningitis: listeria monocytogenes and E. coli*
29
Q
- 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
A
streptococcus pneumoniae
30
Q
What diseases are caused by streptococcus pneumoniae?
A
- 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
Q
- 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+
A
pneumococcal pneumonia
32
Q
- 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
A
bacterial meningitis
33
Q
- 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
A
otitis media
34
Q
Why are asplenic/hyposplenic individuals more susceptible to certain bacterial infections?
A
- 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
Q
- 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
A
streptococci viridans group
*bonus: viridis means green in latin, remember verde for green in Spanish*
36
Q
- 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
A
enterococci
37
Q
- gamma-hemolytic bacteria, grow on bile but not 6.5% NaCl
- strep bovis: most important member, strongly a/w colon cancer
A
group D non-enterococci
38
Q
- 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)
A
bacillus cereus
39
Q
- 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
A
bacillus anthracis
40
Q
- 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
A
clostridium difficile
41
Q
- 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
A
clostridium botulinum
42
Q
- 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
A
clostridium tetani
43
Q
- 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
A
clostridium perfringens
*remember as gas gangrene seen in WWI and WWII*
44
Q
- 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
A
corynebacterium diphtheriae
45
Q
- 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
A
rhodococcus equi
(formerly corynebacterium equi)
46
Q
- 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
A
listeria monocytogenes
47
Q
What are the 3 gram (-) diplococci bacteria?
A
- neisseria meningitis
- neisseria gonorrhea
- moraxella catarrhalis
48
Q
- 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)
A
neisseria meningitis
49
Q
What diseases are caused by neisseria meningitis?
A
- 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
Q
- 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)
A
neisseria gonorrhoeae
51
Q
What diseases are caused by neisseria gonorrhoeae?
A
- 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
Q
- 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
A
moraxella catarrhalis
56
Q
What is unique to E. coli and most of the nosocomial enterobacteriaceae in terms of culturing?
A
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
58
Q
What diseases are caused by E. coli?
A
- 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*
61
Q
What disease is caused by salmonella typhi?
A
- 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
63
Q
- 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
A
yersinia enterocolitica
64
Q
- 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
A
proteus mirabilis
*bonus: E. coli is most common cause of UTI’s in nosocomial setting, however proteus mirabilis should still be considered*
65
Q
- 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
A
klebsiella pneumoniae
66
Q
- nosocomial disease causing enterobacteriaceae
- opportunistic esp in immunocompromised
- both cause pneumonia, UTI’s, wound infections
- both ubiquitous in environment
A
- enterobacter: highly motile and known for its antibiotic resistance (ampicillin and cephalosporins)
- serratia: characteristic red pigment
*card is more for boards than MOD*
67
Q
- 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
A
pseudomonas aeruginosa
68
Q
What diseases does pseudomonas aeruginosa cause?
A
- 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
Q
- 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)
A
bacteroides fragilis
*side note: B. melaninogenicus causes necrotizing pneumonia after aspiration and periodontal disease*
70
Q
- 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
A
vibrio cholerae
72
Q
- 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
A
vibrio vulnificus
73
Q
- 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)
A
campylobacter jejuni
*bonus: other bacteria, yersinia enterocolitica, also mimics case of acute apendicitis*
74
Q
- 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
A
Reiter’s syndrome
(reactive arthritis)
“can’t see, can’t pee, can’t climb a tree”
75
Q
- 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
A
helicobacter pylori
78
Q
- 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%)
A
legionella pneumophilia
*remember American Legion and to drink lemonchellas b/c stagnant waterrrrrr has bacteria*
79
Q
- 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
A
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
Q
What diseases are caused by haemophilus influenzae?
A
- encapsulated (typeable), including Hib:early childhood meningitis,acute epiglottis(fever, sore throat > severewheezing, 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
Q
- 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
A
haemophilus ducreyi
“remember school of fish on gram stain*
86
Q
- 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
A
gardnerella vaginalis
88
Q
- 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
A
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
Q
- 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
A
francisella tularensis
*potential agent of bioterrorism*
90
Q
- 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
A
brucella species
*remember undulant fever*
92
Q
- 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
A
bartonella henselae
*remember cat scratch disease*
96
Q
What other diseases can be caused by chlamydia trachomatis?
A
- 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
Q
What type of lung disease can be caused by chlamydia species?
A
- 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
Q
- 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
A
rickettsia species
99
Q
- 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
A
rickettsia rickettsii
100
Q
- cause of rickettsialpox
- prominent blister/eschar at bite site, fever, generalized rash, self-limiting
- vector: mite
- OX negative (Weil-Felix negative)
A
rickettsia akari
101
Q
- causes high fever, HA, maculopapular rash +/- eschar
- vector: mite
- OX-K (Weil-Felix positive)
- southeastern Asia, Pacific
A
rickettsia tsutsugamushi
102
Q
- causes epidemic typhus
- HA, fever, rash
- vector: louse
- OX-19 (Weil-Felix positive)
- unsanitary, crowded conditions (Napoleonic war)
- carried in flying squirrels, southern US
A
rickettsia prowazekii
103
Q
- 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
A
rickettsia typhi
104
Q
- 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
A
coxiella burnetti
*remember Q fever*
107
Q
What are the characteristics of primary syphilis infection by treponema pallidum?
A
- painless chancre develops after 3-6 weeks of contact
- typically in genital region
108
Q
What are the characteristics of secondary syphilis by treponema pallidum?
A
- 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
Q
What are the characteristics of tertiary syphilis by treponema pallidum?
A
- 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
Q
What are the characteristics of congenital syphilis?
A
- 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)
112
Q
What are the characteristics of treponema pallidum subspecies?
A
- 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
Q
- 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
A
borrelia burgforferi
(Lyme disease)
114
Q
What disease does borrelia burgdorferi cause?
A
- 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*
116
Q
- 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)
A
leptospira interrogans
117
Q
What are the characteristics and organisms within the mycobacterium group?
A
- 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)
119
Q
What is the host immune response to mycobacterium infection?
A
- 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
Q
What are the characteristics of a primary tuberculosis infection?
A
- 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
Q
What are the characteristics of a secondary TB infection?
A
- 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
124
Q
What are the differences between tuberculoid leprosy and lepromatous leprosy?
A
- 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
Q
- 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
A
mycobacterium avium complex
127
Q
- 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)
A
mycoplasma pneumoniae
