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Flashcards in Bacterial Infections Deck (60):

Gram (+) Bacteria

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


Gram (-) Bacteria

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


Staphylococcus aureus

gram (+) COAGULASE (+)
grows in clusters
normal flora on skin
SUPPURATIVE infections
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


Staphylococcus epidermidis

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


Staphylococcus saprophyticus

gram (+), catalase (+), COAGULASE (+)
10-20% of UTI in YOUNG women (usually newly sexually active) = "honeymoon cystitis"


Streptococcus Pyogenes

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


Streptococcus pneumonia

gram (+), catalase (-), alpha hemolytic
normal flora of oropharynx
otitis media


Streptococcus Group B

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


orynebacterium Diptheriae

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


Bordetella Pertusis

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


Haemophilus Influenza

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


Neisseria Meningitides/meningococcus

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


Neisseria gonorrhoeae

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


Haemophilus Ducreyi

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


Calymmatobacterium Granulomatis

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


Escherichia coli

faculatively anaerobic, gram (-) enteropathogenic
intestinal commensals
UTI = #1 cause of all UTIs thanks to pili
Pneumonia = only opportunistically
Neonatal menignitis and sepsis similar to group B strep
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



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



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


Vibrio Cholerae

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


Campyobacter jejuni

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


Yersinia entercolitica/pseudotuberculosis

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



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



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


Legionella pneumophila

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


Pseudomonas aeruginosa

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


Burholderia pseudomallei

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


Clostridium Perfringens

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


Clostridium tetani

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


Clostridium Botulinism

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


Clostridium difficile

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



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


Yersinia Pestis

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


Francisella tularensis

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
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


Bacillus Anthracis

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


Listeria monocytogenes

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


Bartonella henselae

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


Pseudomonas mallei

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


Bartonella bacilliformis

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)



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



Aerobic, gram (+) filamentous, branching bacteria
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


Treponema pallidum

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)


Treponema pertenue

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


T Pallidum endecium

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


Treponema carateum

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


Borrelia burgdorferi

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



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


Borrelia reccurentis

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


Borrelia spp.

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


Tropical Phagedenic Ulcer

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



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


Chlamydia trachomatis D-K

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


Chlamydia trachomatis L1-L3

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


Chlamydia trachmoatis A, B, Ba, and C

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


Chlamydia psittaci

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


Chlamydia pneumoniae

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


Rickettsia rickettsii

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


Rickettsia prowazekii

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


Rickettsia typhi

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


Rickettsia tsutsogamushi

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.
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


Coxiella burnetti

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"