Bacterial Infections Flashcards
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 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
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
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
Streptococcus pneumonia
gram (+), catalase (-), alpha hemolytic normal flora of oropharynx CAPSULE pneumonia otitis media sinusitis meningitis
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: meningitis Broncho or lobar pneumonia epiglottitis 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
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
Salmonella
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
Shigella
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
Klebsiella
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
Enterobacter
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
