Bacterial Infections

Question 1

Gram (+) Bacteria

Answer 1

retain iodine-crystal violet even when decolorized so appear dark blue or purple
THICK peptidoglycan layer
cell wall contains TEICHOIC ACIDS

Question 2

Gram (-) Bacteria

Answer 2

lose iodine-crystal violet even when decolorized so appear red or pink
THIN peptidoglycan layer
LPS = potent endotoxin

Question 3

Staphylococcus aureus

Answer 3

gram (+) COAGULASE (+) 
grows in clusters
normal flora on skin 
SUPPURATIVE infections
Furuncles/styes/carbuncles
Scalded skin syndrome with bullae
OSTEOMYLELITIS in leg bones of children (most common)
Respiratory infections in children <2
Bacterial arthritis
Endocarditis in IV drug users
Toxic Shock syndrome w/ TAMPONS
Food poisoning = preformed toxins so even when cooked still get sick.  Find on custard pies, canned meats, and potato salad
MRSA big problem

Question 4

Staphylococcus epidermidis

Answer 4

gram (+) Catalase (+) COAGULASE (-)
normal flora of skin
most frequent cause of infections associated with medical devices (colonizes catheters and shunts)
see persistent low grade fever

Question 5

Staphylococcus saprophyticus

Answer 5

gram (+), catalase (+), COAGULASE (+)

10-20% of UTI in YOUNG women (usually newly sexually active) = “honeymoon cystitis”

Question 6

Streptococcus Pyogenes

Answer 6

Group A Strep
gram (+), catalase (-), beta hemolytic
Pharyngitis –>RHEUMATIC FEVER or ACUTE POSTSTREPTOCOCCAL GLOMERULONEPHRITIS
SCARLET FEVER = strawberry tongue and rash on chest that spreads to extremities
Erysipelas = erythematous swelling of skin
Impetigo = honey crusted lesions
Cellulitis
Puerperal sepsis = postpartum infection of uterine cavity

Question 7

Streptococcus pneumonia

Answer 7

gram (+), catalase (-), alpha hemolytic
normal flora of oropharynx
CAPSULE
pneumonia
otitis media
sinusitis
meningitis

Question 8

Streptococcus Group B

Answer 8

gram (+), catalase (-), beta hemolytic
grow in short chains
Can be part of normal flora of VAGINA
if mother has it then child is infected as it passes through the birth and is #1 cause of neonatal pneumonia, meningitis, and sepsis

Question 9

orynebacterium Diptheriae

Answer 9

Aerobic, gram (+) rod
vaccine exists
Enters pharynx and proliferates and secretes diptheria toxin (AB subunits) that prevent portein synthesis/elongation that can cardiac necrosis and have neuro effects
major sign is thick, gray, leathery membrane on tonsils

cutaneous diptheria can present as pustule or ulcer

Question 10

Bordetella Pertusis

Answer 10

Vaccine exists
gram (-) coccobacillus
Attaches to respiratory cilia and destroys them
Causes WHOOPING COUGH. Coughing and vomiting make aspiration likelu so bacterial pneumonia is common cause of death

Question 11

Haemophilus Influenza

Answer 11

aerobic, gram(-) coccobacillus
normal flora of nasopharynx
encapsulated strains are much more virulent and cause 95% of bacterimic infections 
can cause:
meningitis
Broncho or lobar pneumonia
epiglottitis
septic arthritis of large weight baring joints
facial cellulitis

Question 12

Neisseria Meningitides/meningococcus

Answer 12

PAIRED, bean shaped gram (-) cocci
LPS can cause shock
Meningitis (dorms or barracks)
Waterhouse-friderichsen sndrome (necrosis of both adrenals

Question 13

Neisseria gonorrhoeae

Answer 13

gram (-) diplococcus
men =purulent urethritis
women = endocervitis, PID, endometritis, salpingitis that all can be purulent
neonates = conjunctivitis and blindness
Septic Arthritis

Question 14

Haemophilus Ducreyi

Answer 14

small gram (-) bacillus
clusters of parallel bacilli and as chains resembling school of fish
STD that causes chancroid = genital ulcer then unilateral, painful, suppurativeinguinal lymphadenitis (bubo)
seen especially in Africa and Asia

Question 15

Calymmatobacterium Granulomatis

Answer 15

Granuloma inguinale = STD = raised, soft, beefy red superficial ulcer.
See DONOVAN BODIES = macrophages with many bateria inside them
massive scarring of the dermis may obstruct lymphatics and cause elephantiasis

Question 16

Escherichia coli

Answer 16

faculatively anaerobic, gram (-) enteropathogenic
intestinal commensals
UTI = #1 cause of all UTIs thanks to pili
Pyelonephritis
Pneumonia = only opportunistically
Sepsis/shock
Neonatal menignitis and sepsis similar to group B strep
Diarrhea
1) enterotoxigenic = travelers diarrhea =secretory dysfunction
2)enteropathogenic = hospitalized infant under 2yrs
3)Enterohemorrhagic = HUS = bloody diarrhea after eating bad meat
4) Enteroinvasive = food borne dysentery indistinguishable for shigella

Question 17

Salmonella

Answer 17

gram (-) rods
entercolitis = improperly cooked, pasteurizes, or irradiated food. toxins injure intestinal cells and get diarrhea 12-48hrs after ingesting
TYPHOID FEVER = fecal oral route or contaminated water and food. s. typhi invades peyers patches and cause necrosis and ulcers in longitudinal orientation of bowel along with systemic illness and fever

Question 18

Shigella

Answer 18

aerobic gram (-) rod
fecal-oral route
self limited disease with abdominal pain and bloody, mucoid stools
shiga toxin interferes with 60s ribosomal subunit to inhibit protein synthesis 
necrotizing infection of the distal small bowel and colon.  Pseudomemebranes appear on severely affected parts

Question 19

Vibrio Cholerae

Answer 19

aerobic, curved gram (-) rod
epidemic enteritis from contaminated water or shellfish
proliferates in lumen of small intestine and releases cholera toxin that via increased cAMP causes PROFUSE watery diarrhea “rice water” appearance, dehydration, shock and death within 24hrs

Question 20

Campyobacter jejuni

Answer 20

microaerophilic, curved gram (-) rod
Most common cause of bacterial diarrhea worldwide
raw milk and inadequately cooked poultry and meat or person to person via fecal-oral route
associated with Guillian-Barre syndrome

Question 21

Yersinia entercolitica/pseudotuberculosis

Answer 21

gram (-) coccoid or rod shaped bacteria faculative anaerobes found in feces of animals
abdominal pain in lower R quadrant that cant be mistaken for appendicitis
produces painful diarrhea

Question 22

Klebsiella

Answer 22

short, encapsulated, gram (-) bacilli
nosocomial infections including UTI and pneumonia with catheters and tubes or superimposa on a upper viral illnes
cause necrotizing lobar pneumonia with THICK MUCOID SPUTUM

Question 23

Enterobacter

Answer 23

short, encapsulated, gram (-) bacilli
nosocomial infections including UTI and pneumonia with catheters and tubes or superimposa on a upper viral illnes
cause necrotizing lobar pneumonia with THICK MUCOID SPUTUM

Question 24

Legionella pneumophila

Answer 24

aerobic bacilus that has structure of gram (-) but STAINS POORLY
Infect water twoers and water heaters
Pneumonia = Legionnaires disease = survivie in alveolar macrophages by preventing fusion of phagosome w/ lysosome. Acute bronchopneumonia usually unilateral, diffuse, patchy consolidation
Pontiac Fever = self limited flur like illness with fever, myalgias, and headache

Question 25

Pseudomonas aeruginosa

Answer 25

extreme antibiotic resistance pneumonia, wound infections, UTI, and rapidly progress sepsis CF, diabetes and burns predispose invade small arteries and veins and cause ecythema gangrenosum

Question 26

Burholderia pseudomallei

Answer 26

``` small gram (-) baccilus in soil and water of SOUTH EAST ASIA/VIETNAM penetrate wounds and cause Acute meliodosis = vary from tracheobronchitis to cavitary pneumonia with blood tinged sputum, fever, hepatosplenomegaly and jaundice. Diarrhea . If becomes septicemic get discrete ABSCESSES throughout the body ```

Question 27

Clostridium Perfringens

Answer 27

gram (+), spore forming, obligate anaerobic bacilispores survive cooking and germinate when food is allowed to stand. ingested and sporulate in small intestine and release exotoxins that kill enterocytes and cause diarrhea . in New guinea type C produces an entertoxin that causes necrotizing enterocolitis and leads to peritonitis. more serious in children after "pig feasts" Type A can cause gas gangrene

Question 28

Clostridium tetani

Answer 28

gram (+), spore forming, obligate anaerobic bacili contaminates wounds and proliferates in tissues where it releases exotoxin that prevents release of INHIBITORY NTs so get spastic paralysis

Question 29

Clostridium Botulinism

Answer 29

gram (+), spore forming, obligate anaerobic bacili see in improperly home canned foods. c. notulinism reproduces and releases lots of neurotoxin which when ingested inhibits ACh release so get descending flaccid paralysis

Question 30

Clostridium difficile

Answer 30

gram (+), spore forming, obligate anaerobic bacili causes a acute necrotizing infection of terminal small bowel and colon that results in diarrhea. called pseduomembranous colitis toxin A causes fluid secretion and toxin B is cytopathic See after a bouth of antibiotics that destoryed normal flora

Question 31

Brucella

Answer 31

Small aerobic, gram (-) rods waxing and waning febrile episodes with weight loss and fatigue Infect sheep, cattle, swine and dogs. See in ranchers, vets, and slaughterhouse workers that come in contact with animal parts frequently B. Abortus = noncaseating granulomas in liver, spleen, lymph nodes, and bone marrow treat with tetracycline

Question 32

Yersinia Pestis

Answer 32

Short gram (-) rods that stain heavily on the ends especailly with Giemsa stain bubonic, septicemic, or pneumonic plague bacteria are found in rodents and often transferred to human via bites or fleas

Question 33

Francisella tularensis

Answer 33

small gram (-) coccobacillus reservoir is rodents and rabbits and gets to humans when they contact infected animals or bites from ticks, deer flies, mosquitoes, inhalation of aerosols Lung shows frim consolidated necrotic areas that resemble TB Presentations 1) Ulceroglandular = most common = erythematous papule at site of infection then pustule that ulcerates. get bactermia with fever, headache, and myalgias. Secondary pneumonia and shock are common 2) Oculoglandular = primary conjunctival papule which forms a pustule and ulcerates 3) Typhoidal = fever, hepatospelnomegaly and toxemia 4) Pneumonic = pneumonia is major feature treat with streptomyocin

Question 34

Bacillus Anthracis

Answer 34

Large, spore forming, gram (+) rod infect her adnimals and spores can remian in soil for years and enter human through breaks in skin or inhalation Gerimnate in the body and release a potent necrotizing toxinthat is rapidly fatal if it disseminates cutaneous form causes a malignant pustule inhalational is bad as it progresses to respiratory failure and shock septicemic anthrax usually follows pulmonary GI = fulminant diarrhea and ascites

Question 35

Listeria monocytogenes

Answer 35

small, motile, gram (+) coccobacillus found in unpasteurized cheese and dairy products as well as soil and water escape phagolysosomes and can hijack cell contractile elements to shoot themselves into neighboring cells without ever being exposed to extracellular environment Maternal infection early in pregnancy maylead to abortion or premature delivery infants have respiratory distress, papules, leukopenia, and throbocytopenia. Often fatal or have longterm neuor sequalae Speticemic listeriosis is severe febrile illness common in immunodeficient patients. May develop shock and DIC

Question 36

Bartonella henselae

Answer 36

gram (-) rods that are hard to culture but easily seen in tissue sections stained with silver Cat scratch disease = suppurative and granulomatous lymphadenitis

Question 37

Pseudomonas mallei

Answer 37

``` small gram (-) , nonmotile bacillus humans acquire infection from infected equines through broken skin or aerosols Acute glanders = bacteremia, severe prostration, and fever. Granulomatous abscess may from in subctuaneous tissue and organs. Almost always fatal Chronic glanders = low grade fever, draining abscess of skin, lymphadenopathy and hepatosplenomegaly. Granulmoas in organs mimic TB ```

Question 38

Bartonella bacilliformis

Answer 38

small multiflagellated, gram (-) coccobacillus Peru, ecuador, and colombia and transmitted by sandflies bartonellosis = hemolytic fever followed monhts later by chronic dermal phase (small hemangioma-like lesions stud the dermis)

Question 39

Actinomyces

Answer 39

BRANCHING, filamentous gram (+) rods normal flora in oropharynx, GI, and vagina only cause disease when they are innoculated into deeper tissue with anaerobic environment Actinomycosis = form multiple abscesses connected by sinus tracts with SULFUR GRANULES in cervicofacial, thoracic, abdominal or pelvic region

Question 40

Nocardia

Answer 40

Aerobic, gram (+) filamentous, branching bacteria WEAKLY ACID FAST use silver stain to see in tissues Found in soils and people with deficient cell mediated immunity can get a suppurative respiratory infection that can spread to brain and skin

Question 41

Treponema pallidum

Answer 41

spirochette with cell wall structure of gram (-) but stain poorly so have to darkfield microscopy or silver STD Syphillis primary = chancres that erode to painless ulcer Secondary = spreads systemically to skin, lymph, meninges and has obliterative endarteritis. Get erythematous and maculopapular rash of trunk/extremities/hands, condyloma lata, lesions of mucous membranes, and asymptomatic seeding of meninges Tertiary = gummas, syphilitic aorta (tree bark), neurosyphilis congenital = still born, death, or rhinitis, saddle nose, saber shins (anterior bowing of legs), and hutchinson teeth (peg shaped upper incisors)

Question 42

Treponema pertenue

Answer 42

spirochette that looks exactly like T. pallidum Yaws = tropical disease that spreads by skin-skin contact Primary = mother yaw = single "rasberry like" papilloma Secondary = disseminated eruption of smaller yaws. can be very painful and cause people to walk on sides of their feet Late = cutaneous gummas which are destuctive of face and upper airways

Question 43

T Pallidum endecium

Answer 43

subspecies of t. pallidum | Bejel/endemic syphillis = resembles syphilis but spread by mouth to mouth or mouth to breast

Question 44

Treponema carateum

Answer 44

spirochette Pinta = variably colored spots on the skin remote arid regions and river valleys of American tropics

Question 45

Borrelia burgdorferi

Answer 45

large. microaerophilic spirochete tick bite then get Lyme Stage 1 = eytheme chronicum migrans, bullseye rash, malaise, fatigue, headache, and fever Stage2 = migratory musculoskeletal pain. Can also see myocarditis or meningitis in patients Stage 3 = joint, skin, and neuro abnormalities

Question 46

Leptospira

Answer 46

spirochete mild, self-limited febrile disease that can progress to hepatic and renal failure get in through skin abrasions that come in contact with rats, water or mud Leptospiremic phase = abrupt fever, chills headache, and myalgia Immune phase = meningeal irritation, hepatic and renal failure, widespread hemmorhage and shock

Question 47

Borrelia reccurentis

Answer 47

spirochete Epidemic relapsing fever = humans only reservoir and spread by bite of louse. If you crush louse then borrelia get out and penetrate through bite marks arthralgias, myalgia, lethargy, fever, headache, hepatospenomegaly, petchiae of skin body clears but antigenic variation causes disease to come back again in about a week fatal form = spleen enlarged and contains miliary microabscesses treat with tetracycline

Question 48

Borrelia spp.

Answer 48

spirochete Endemic relapsing fever = transmitted from rodents to humans by infected tick arthralgias, myalgia, lethargy, fever, headache, hepatospenomegaly, petchiae of skin body clears but antigenic variation causes disease to come back again in about a week fatal form = spleen enlarged and contains miliary microabscesses treat with tetracycline

Question 49

Tropical Phagedenic Ulcer

Answer 49

painful necrotizing lesion of skin and subcutaneous tissues in tropical climates bacillus fusiformus and treponema vincentii usually found cup-shaped crater/ulcer that can expose underlying tendons and bones

Question 50

Noma

Answer 50

mix of bacteria T. vincentii, B. fusiformis, bacteriodes and corynebacterium rapidly progressive cutaneous necrosis that is destructive, disfiguring, and usually unilateral

Question 51

Chlamydia trachomatis D-K

Answer 51

obligate intracellular parasite with infectious rugged elementary body amd metabolically active reticulate body one of the most common STDs men = dysuria, urgency and sometimes purulent discharge women = cervicitis with mucopurulent drainage from cervical os newborns = conjunctivitis and pneumonia

Question 52

Chlamydia trachomatis L1-L3

Answer 52

lymphogranuloma venerum = ulcer in genital area typically that thne transports through lymphatics to cause necrotizing lymphadenitis can causes strictures, fistulas, and elephantiasis

Question 53

Chlamydia trachmoatis A, B, Ba, and C

Answer 53

is a leading cause of blindess in developing countries causes progressive scars of conjunctiva and cornea find small yellowgrains of lymphoid aggregates beneath the palpebral conunctivae spread by direct contact, fomites, water, and flies

Question 54

Chlamydia psittaci

Answer 54

spread by infected birds infects pulmonary macrophages which carry it to liver and spleen and gets into blood. Get systemic disease with diffuse involvement of the lungs (interstitial pneumonia) persistent dry cough with constitutional symptoms

Question 55

Chlamydia pneumoniae

Answer 55

acute self limited, mild respiratory tract infections including pneumonia person to person fever, sore throat, and cough

Question 56

Rickettsia rickettsii

Answer 56

gram (-), coccobacillary, obligate intracellular bacteria that reproduce by binary fission target endothelial cells of capillaries and small blood vessels rocky mountain spotted fever = tick bite, systemic vasculitis and DIC. Fever headache, myalgia, maculopapular eruption that become petechial spreading CENTRIPETALLY from distal extremties to trunk. Also get lesions on palms and soles

Question 57

Rickettsia prowazekii

Answer 57

gram (-), coccobacillary, obligate intracellular bacteria that reproduce by binary fission target endothelial cells of capillaries and small blood vessels Epidemic (louse born) typhus = louse feces on skin then innoculated when you scratch. get mast cells, lyphocytes, plasma cells, and macrophages arranged as TYPHUS NODULES around arterioles and capillaries. get fever, headache, myaglia, rash simmilar to rocky mountain. Other complications include encephalitis, myocarditis, gangrene of skin, penumonia, and interstitial nephritis overcrowded areas

Question 58

Rickettsia typhi

Answer 58

gram (-), coccobacillary, obligate intracellular bacteria that reproduce by binary fission target endothelial cells of capillaries and small blood vessels Endemic (Murine) typhus = humans get in way of rat-flea-rat cycle. Feces of flea. milder than epidemuc (louse-borne) typhus. pulmonary infection most common. See in areas with lots of rats

Question 59

Rickettsia tsutsogamushi

Answer 59

gram (-), coccobacillary, obligate intracellular bacteria that reproduce by binary fission target endothelial cells of capillaries and small blood vessels Scrub typhus = rodents natural reservoir but mites/chiggers pass it into larvae that sometimes feed on humans. SOUTHEAST ASIA multiocculated vesicle at innoculation site that ulcerates and becomes an eschar. Lesion heals and then get headache and fever followed by pneumonia, macular raash. lymphadenopathy, and hepatosplenomegaly

Question 60

Coxiella burnetti

Answer 60

coccobacilus with gram (-) wall enters cells passively by phagocytosis by macrophages common in farm animals and begins with inhalation of organisms Q Fever = self limited, systemic infection with fever, headache, myalgia. Lungs show single or multiple areas of conolidation (gimesa stain to check for organism in macrophages). multiple microscopic granulomas with "fibrin ring"