bacteria and viruses Flashcards
what type of virus is rotavirus?
segmented, double-stranded RNA genome
-hubbed wheel with spokes
what type of virus in adenovirus?
complex double-stranded DNA
-3rd most common cause of gastroenteritis in infants and kids
what is type of virus is hep B?
double stranded circular DNA
what type of viruis is astrovirus and norwalk?
single-stranded RNA
what is the second most common cuase of viral gastroenteristis in young children?
astrovirus
what is the most common cause of early prosthetic valve endocarditis?
S. epidermidis
what ist he most common cause of late prosthetic valve endocarditis?
staph. aureus, streptococcus, gram neg bacilli, or multiple pathosgents
what is the most common cause of cervicofacial infections undergoing dental work?
Actinomyces israelii
*anaerobe and would not favor an infection site in the blood strem
what is Nocardia asteroides?
an aerobic filamentous bacterium that cuases chronic lobar pneumonia that may metastasize to the brain
*immunocompromised pts
found in soil and aquatic environments
what is a common cause of cutaneous mycoses?
trichophyton rubrum
-tinea corporis, tinea, cruris, tinea pedis
what is the most common bacteria found in a dog/cat bite wound that can cause an abscess?
Pasteurella multocida
what is Bartonella henselae?
very small, gram-negative bacterium that is closely related to the Rickettsia, although it is able to grow on inert media. It is the cause of cat-scratch disease (a local, chronic lymphadenitis most commonly seen in children) and bacillary angiomatosis (seen particularly in AIDS patients). In this latter patient population, the organism causes proliferation of blood and lymphatic vessels, causing a characteristic mulberry lesion in the skin and subcutaneous tissues of the afflicted individual.
what is brucella canis?
a gram negative rod that is a zoonotic agent-normal host is a dog, but it can cause undulation febrile dz w/ malaise, lymphandenopathy, and hepatosplenomegaly
what is toxocara canis?
a common intestinal parasite of dogs- metazoan parasite that causes visceral larve migrans
what is a Yersinia enterocolitica infection?
- acute ileitis and D
- fecal-oral route and infects the terminal ileum
- RLQ tenderness
- can be distinguished from appendicitis will have difficutly moving bowesl
what does campylobacter jejuni present with?
bloody or non bloody D
what does salmonella enteritidis present with?
an acute diarrheal illness w/ diffuse pain
what is cholera?
vibrio cholerae- produces a toxin that activates adnylyl cyclase in intestinal epithemial cells of the small intestine
what does the cholera toin do?
it caues hypersecretion of water and Cl ion=massive D
what causes death by cholear?
hypovolemia
when do epidemis of cholear occur?
times of war, overcrowding and famine, and where sanitation is inadequate
how is cholera spread?
ingestion of contaminated food or water
what are the clinical findings of cholera?
sudden onset of severe, frequent “rice water” D (gray, turbid, w/o odor, blood, or pus); dehydrations, hypotension,, electrolyte imbalance
dx studies of cholear?
stool cultures are postitive for V. cholerae; serum agllutination test
what are the tx of cholera?
replacement of fluids and electrolytes; oral rehydration w/ water containing salt and sugar; severe casese need IV fluids
what abx can be used for cholear?
tetracyclin, ampiclllin, chloramphenicol, bactrim, FQ
how is salmonella transmitted?
via ingestion of contaminated food or water
what are the 3 patterns of salmonella?
1) enteric (typhoid fever)
2) gastroenteritis
3) bacteremia
what is the incubation period for typhoid fever?
5- 14 days
what is the PP of typhoid fever?
organism enter the mucosal epithelium of the intestines and invade adn replicate w/ in the macrophages of peyer’s patches, mesenteric lymphnodes,and spleen
what accompanies an typhoid fever infecction?
bacteremia
does typhoid fever have a prodorome?1
yes! fever, maliase, HA, cough, sore throat
what develops as fever increased in TF?
abdominal pain, distendiont, constipation, and or D
what kind of Diarrhea does TF have?
pea soup
when does the fever peak? for TF?
on days 7-10: pt appears toxic, but then generally improves; some may relapse
what are PE findings in typhoid fever?
splenomegaly, abdominal distention and tenderness, bradycardia
when does a rash develop in TF?
after the second wk: pink papules, primarily on the trunk, that fade with pressure
how can TF be dx?
can be isolated from blood during first week of illness, later blood cultures will likely be negf. NO stool culture
what are complications of tf?
occure in 30% of untrx cases: intestinal hemorrhage, urinary retention, PNA, thrombophlebitis, myocardidits psychosis, cholecystitis, nephritis, oseomyelitis, miningitis
tx of TF
ampicillin, chloramphenicol, bactrim resistance in increasing, can use ceftriaxone or FQ
what population is Ceftriaxone and FQ contraindicated in?
chilren and pregos
how is TF prevented?
immunizatios, but not very effective
; clean water and proper waste disposal
Salmonella gastroenteritis (Salm. G)
the most common form of salmonella infx
what is the incubation period for Salm. G?
8-48 hoursafter ingestion of contaiminated food or drink
what are teh sx of SaG?
fever, N/V, crampy abdominal pain, bloody D that last 3-5 days. dx = stool culutre
what is the tx for SaG
self limited, tx is sx.
severely ill, sickle cell, or pts who develop bacteremia: bactrim, ampicillin or cipro
salmonella bacteremia features?
prolonged or recurrent fevers w/ bacteremia and local infxn in bone joints, pleura, pericardium, lungs and other sits
what pt population is most likely to get Sal. B?
immunosuppressed
what is tx for salm. B?
same a typhoid; possilby cipro
What is Shigellosis?
3 bacteria: S. sonnei, S. flexneri, and S. dysenteria= most common species that cause dysentary
what are the CF of Shig?
+abrupt illness w/ D, lower abdominal cramps, and tenesmus accompanied by fever, chills,, anorexia, HA, and malaise
what do stools look like in Shig?
loose and mixed w/ blood or mucus;
what are PE findings in Shig?
abdominal tenderness, dehydration
what may be seen in those with HLA-B27 and shig infxn?
reactive arthritis due to a temporary disaccharidase def
how is a shig infexn dx?
stool: + for WBC and RBC, culture will show shig
sigmoidoscopy: inflamed, engorged mucose, punctate lesions, or ulcers
tx of shig infx?
replacement of fluid volume
abx: bactrim; OR cipro and FQ
what abx is NOT effective against shig?
AMOXICILLIN
what is diptheria?
cornyebacterium diptheria is an organism that really likes the mucous membranes, especially the respiratory tract
what does c. diptheria producue?
a exotoxin that causes myocarditis and neuropathy
what are CF of diptheria?
+nasal infection: nasal discharge
+laryngeal infection: upper airway and bronchial obsturction
+pharyngeal infection: most common form: tenacious gray membrane covers the tonsils and pharynx (mild sore throat, fever, maliase)
what are severe diptheria problems?
myocarditis and neuropathy of the cranial nerves
how is diptheria dx?
clinical, but culture wll confirm
how is diptheria tx?
horse serum antitoxin from CDC
+if airway obstruction: removal of membrane w/ larynogosxopy
+PCN or erythromycin
+pts should be isolated untio 3 neg pharyngeal cultures
do you tx contacts of dptheria pts?
yes w. eyrthormycin
what are the preventions of dipthera?
-DTaP, Td
Pertussis
Bordetella p. is a gram- pleomoprhic bacillus (HUMANS are the sole reserviour)
what pt popluation is most likely to get pertussis?
premature infants and in those w/ cardica, plmonary, or NM disorders
+adults and kids tend to have milder dz
what are the clinical manifestations of Pertussis?
1) catarrhal stage
2) paroxysmal
3) convalescent
what is the catarrhal stage?
insidious onset of sneezing, coryza, loss of appetitis, malaise along with hacking cough that is most prominent at night
-most infx stage, and often misdiagnosed as an upper respiratory viral illness
what is the paroxysmal stage:
spasms of rapid coughing fits followed by deep, high-pitched inspiration (the whoop)
+can last for several min
+infants are at high risk of apnea
what is the convalescent stage?
decrease in frequency and severity of paroxysms- usually begins 4 wks after onset of cough and may persist for a few more wks
what about adults and pertussis?
often misdiagnosed, if cough greater than 2 wks considre on ddx
dx of pertussis
- culture on special media
- PCR assayas
- WBC mildly elevaeted
what is the tx of choice for pertussis?
erythromycin; 2cd line; other macrolids, bactrim
what is the vaccine of choice for adults to prevent pertussis?
Tdap
