Micro - Systems Flashcards
A neonate gets an infection in utero and develops notched teeth, saddle nose, short maxilla, and saber shins. Diagnosis?
Syphilis
A patient has vesicular rashes on the palms and soles and ulcers in the oral mucosa. What caused this?
Coxsackie A virus
What causes Prion diseases?
Prion protein (PrPc: a normal cellular protein) gets converted into a -pleated form (PrPsc), which destroys normal tissue
What clinical manifestations does prion accumulation cause?
Spongiform encephalopathy, ataxia, dementia, and death
Why does the β-pleated form of Prion protein cause encephalopathy?
Because it is resistant to degradation and facilitates conversion of more prion
protein to the β-pleated (pathologic) form
_____ is an example of an inherited prion disease; _____ is an example of an
acquired prion disease; _____ is an example of a sporadic prion disease.
Gerstmann-Sträussler-Scheinker syndrome; kuru; Creutzfeldt-Jakob disease
Staphylococcus epidermidis is considered normal flora of what parts of the body?
The skin and nose
Staphylococcus aureus normally colonizes what part of the body?
The nose
In which part of the body are viridans streptococci considered normal flora?
The oropharynx
Where in the body is Streptococcus mutans part of the normal dominant flora?
The dental plaque
Which bacteria are considered part of the normal dominant flora of the colon?
Bacteroides fragilis and to a lesser extent, Escherichia coli
Which three bacteria are considered dominant flora in the vagina?
Lactobacillus, Escherichia coli, and group B Streptococcus
What two organisms that causes food poisoning are found in contaminated
seafood?
Vibrio parahaemolyticus and Vibrio vulnificus
What gram-positive rod causes food poisoning associated with reheated rice?
Bacillus cereus (remember: Food poisoning from reheated rice? Be serious!)
Given that symptoms of Staphylococcus aureus food poisoning can begin within
an hour, symptoms are caused by what?
Preformed toxins
Which two organisms cause food poisoning that starts quickly and ends quickly?
Staphylococcus aureus and Bacillus cereus
Staphylococcus aureus preformed toxin is found in what types of foods?
Meats, mayonnaise, and custard
Which bacteria are associated with food poisoning after consumption of reheated
meat dishes?
Clostridium perfringens
Which bacteria are associated with food poisoning after consumption of
improperly canned foods (ie, bulging cans)?
Clostridium botulinum
Which gram-negative rod causes food poisoning in undercooked meat?
Escherichia coli
What bacteria cause food poisoning that is associated with contaminated poultry,
meat, and eggs?
Salmonella
In addition to causing food poisoning, what other type of infection can Vibrio
vulnificus cause?
Wound infections (after contact with shellfish or contaminated water)
Name eight organisms that can cause bloody diarrhea.
Campylobacter jejuni, Salmonella, Shigella, enterohemorrhagic Escherichia coli,
enteroinvasive Escherichia coli, Yersinia enterocolitica, Clostridium difficile,
and Entamoeba histolytica
Name eight organisms (bacteria, protozoa and viruses) that can cause watery
diarrhea.
Enterotoxigenic Escherichia coli, Vibrio cholerae, Clostridium perfringens,
Giardia, Cryptosporidium(in immunocompromised patients), rotavirus,
adenovirus, and Norwalk virus
What comma- or S-shaped organisms cause bloody diarrhea, grow at 42°C, and are
oxidase positive?
Campylobacter jejuni
What nonlactose-fermenting, motile, gram-negative rod causes bloody diarrhea?
Salmonella
What nonlactose-fermenting, nonmotile, gram-negative rod has a low ID50 and
causes dysentery?
Shigella
Infection with what organism can cause hemolytic uremic syndrome and a bloody
diarrhea that is caused by a Shiga-like toxin?
Enterohemorrhagic Escherichia coli
How does enterohemorrhagic Escherichia colicause bloody diarrhea?
By the invasion of the colonic mucosa
What organism causes bloody diarrhea and pseudoappendicitis and is associated
with outbreaks in day-care centers?
Yersinia enterocolitica
Pseudomembranous colitis is caused by which organism?
Clostridium difficile
Which protozoan causes blood diarrhea as well as liver abscesses?
Entamoeba histolytica
Enterotoxigenic Escherichia colicauses travelers diarrhea by producing what two
toxins?
Labile toxins and stabile toxins
What comma-shaped organisms cause watery diarrhea characterized by “rice-
water” stools?
Vibrio cholerae
Which gram-positive bacillus that causes gas gangrene also causes watery
diarrhea?
Clostridium perfringens
Which two protozoa cause significant diarrhea in immunocompetent individuals?
Giardia and Cryptosporidium
Which protozoan can cause significant watery diarrhea in immunocompromised
patients but mild disease in immunocompetent hosts?
Cryptosporidium
Which viruses can cause watery diarrhea?
Rotavirus, adenovirus, and Norwalk virus
What are the two most common causes of pneumonia in neonates?
Group B streptococci and Escherichia coli
What are the four most common causes of pneumonia in children 4 weeks to 18
years old?
Viruses (Respiratory syncytial virus), Mycoplasma, Chlamydia pneumoniae,
and Streptococcus pneumoniae(remember: Runts May Cough Sputum)
What are the three most common causes of pneumonia in adults 18-40 years of
age?
Mycoplasma, Chlamydia pneumoniae, and Streptococcus pneumoniae
What are the five most common causes of pneumonia in adults 40-65 years of age?
Streptococcus pneumoniae, Haemophilus influenzae, anaerobes, viruses
and Mycoplasma
What are the most common causes of pneumonia among the elderly?
Streptococcus pneumoniae, Haemophilus influenzae, gram-negative rods,
anaerobes, and viruses
Which pathogens are usually acquired as a nosocomial pneumonia?
Staphylococci and enteric gram-negative rods, which are rarely acquired in the
community
In addition to common causes, which organisms should be considered in
immunocompromised patients with pneumonia?
Staphylococci, gram-negative rods, fungi, viruses, and (in patients with HIV
infection) Pneumocystis jiroveci
In aspiration pneumonia, one would expect to see what type of organisms?
Anaerobes
Which three pathogens commonly cause pneumonia among alcoholics and
intravenous drug users?
Streptococcus pneumoniae, Klebsiella, and Staphylococcus
Postviral pneumonia is commonly caused by what pathogens?
Staphylococcusand Haemophilus influenzae
Which three pathogens commonly cause atypical pneumonia?
Mycoplasma, Legionella, and Chlamydia
Which bacterium often causes pneumonia in patients with cystic fibrosis?
Pseudomonas
In newborns up to 6 months of age, what three pathogens are most commonly
responsible for meningitis?
Group B streptococcus, Escherichia coli, and Listeria monocytogenes
In children between 6 months and 6 years of age, what four pathogens are most
commonly responsible for meningitis?
Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae type
B, and enteroviruses
In people 6 to 60 years old, what four pathogens are most commonly responsible
for causing meningitis?
Neisseria meningitidis, enteroviruses, Streptococcus pneumoniae, and herpes
simplex virus
In people 60 years of age and older, what three pathogens are most commonly responsible for causing meningitis?
Streptococcus pneumoniae, Listeria, and gram-negative rods
What five viruses are common causes of meningitis?
Enteroviruses (especially coxsackievirus), herpes simplex virus, HIV, West Nile
virus, and varicella zoster virus
What four pathogens commonly cause central nervous system disease in HIV-
positive patients?
Cryptococcus, cytomegalovirus, toxoplasmosis (brain abscess), and JC virus
(progressive multifocal leukoencephalopathy)
How has the incidence of bacterial meningitis changed in the past 20 years?
It has decreased due to the use of the Haemophilus influenzaevaccine
What cerebrospinal fluid findings are indicative of bacterial meningitis?
Increased pressure, polymorphonuclear leukocyte predominance, increased protein,
and decreased sugar
What cerebrospinal findings are indicative of fungal or tubercular meningitis?
Increased pressure, lymphocyte predominance, increased protein, and decreased
sugar
What cerebrospinal findings are indicative of viral meningitis?
Normal or increased pressure, lymphocyte predominance, normal or elevated
protein and normal sugar
What is the difference in cerebrospinal fluid findings between bacterial and
fungal/tubercular meningitides?
Both show increased pressure and protein and decreased sugar; however,
polymorphonuclear leukocytes are found with bacterial causes, whereas
lymphocytes are found with fungal/tubercular causes
In general, what is the most common cause of osteomyelitis?
Staphylococcus aureus (assume this cause if there is no other information)
In sexually active people, what pathogen can rarely cause osteomyelitis and, more
commonly, septic arthritis?
Neisseria gonorrhoeae
Osteomyelitis in diabetic and drug-addicted individuals may be caused by what
organism?
Pseudomonas aeruginosa
Which otherwise unlikely organism can cause osteomyelitis in patients with sickle
cell disease?
Salmonella
Which otherwise unlikely organism can cause osteomyelitis in patients with
prosthetic replacement?
Staphylococcus aureus and Staphylococcus epidermidis
What is vertebral osteomyelitis caused by tuberculosis called?
Potts disease
In what age group does osteomyelitis most frequently occur?
Children
What two nonspecific laboratory findings are classically found in osteomyelitis?
Elevated erythrocyte sedimentation rate and C-reactive protein
What organism is implicated in osteomyelitis resulting from dog bites or cat
scratches?
Pasteurella multocida
Why are urinary tract infections 10 times more likely to occur in women than in
men?
Women have a short urethra that can be colonized by fecal flora
Name seven factors that can predispose patients to urinary tract infections.
Flow obstruction, kidney surgery, catheterization, genitourinary abnormalities,
diabetes, and pregnancy
Elderly males with what condition are predisposed to urinary tract infections?
Enlarged prostate
What is the most common route of urinary tract infection?
Ascent of bacteria from the urethra to the bladder
What are the symptoms of urinary tract infection?
Dysuria, frequency, urgency and suprapubic pain
What are the symptoms of pyelonephritis?
Fever, chills, flank pain, and costovertebral angle tenderness
What is found on urinalysis of a patient with cystitis?
White blood cells but not white blood cell casts, which would indicate kidney
pathology
What is found on urinalysis of a patient with pyelonephritis?
White blood cell casts and red blood cells (hematuria)
How does pyelonephritis develop from a lower urinary tract infection?
Further ascent of bacteria from the bladder to the kidneys
Infants with what conditions are more prone to urinary tract infections?
Vesicoureteral reflux and other congenital anomalies of the urinary tract
What does a positive leukocyte esterase test indicate on urinalysis?
Bacterial urinary tract infection
What does a positive nitrite test indicate on urinalysis?
Gram-negative bacterial urinary tract infection
Name seven bacteria that cause UTIs.
Serratia marcescens, Staphlococcus saprophyticus, Escherichia coli, Enterobacter
cloacae, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas
aeruginosa(remember: SSEEK PP)
What organism causes nosocomial, drug-resistant urinary tract infection and
produces a red pigment?
Serratia marcescens
The colonies of what leading cause of urinary tract infection show a metallic sheen
in eosin methylene blue agar?
Escherichia coli
Enterobacter cloacae often causes _____ (community-acquired/nosocomial)
urinary tract infection, and it is often _____ (drug susceptible/drug resistant).
Nosocomial; drug resistant
What organism, which is characterized by a large mucoid capsule and viscous
colonies, causes urinary tract infection and pneumonia in humans?
Klebsiella pneumoniae
The production of what enzyme by Proteus mirabilisis associated with struvite
stones?
Urease; the enzyme makes urine more basic, which promotes struvite stone
formation
Blue-green pigment and fruity odor characterize which organism that causes
urinary tract infection?
Pseudomonas aeruginosa
In sexually active women, what is the second leading cause of community acquired
urinary tract infections?
Staphlococus saphrophyticus
What are the ToRCHeS infections?
Toxoplasmosis, Rubella, Cytomegalovirus, Herpes simplex virus and HIV,
and Syphilis
What is the classic triad found in many neonatal Toxoplasma gondii infections?
Chorioretinitis, intracranial calcifications, and hydrocephalus
An neonate is found to have deafness, cataracts, a patent ductus arteriosus, and
pulmonary artery stenosis. What infection did his mother most likely have while
the neonate was in utero?
Rubella
An infant presents with encephalitis and vesicular skin lesions. What infection did
this infant likely contract during vaginal birth?
Herpes simplex virus type 2
What are the three congenitally acquired infections in which the mother is usually
asymptomatic with the infectious agent?
Cytomegalovirus, toxoplasmosis, and herpes simplex virus type 2
What rash is commonly associated with neonatal rubella?
A “blueberry muffin” rash
How does HIV commonly present in neonates?
Chronic diarrhea, recurrent infections, and failure to thrive
If a neonate survives in utero infection of syphilis, how does s/he commonly
present?
Notched teeth, saddle nose, short maxilla, and saber shins
What physical findings of the neonate are common to most ToRCHeS infections?
Jaundice, hepatosplenomegaly, growth retardation, and thrombocytopenia
Aside from the infections in the ToRCHeS mnemonic, what are three other
important infectious agents that can pass from mother to fetus?
Streptococcus agalactiae (group B strep), Escherichia coliand Listeria monocytogenes; all are common causes of meningitis in neonates
How does a pregnant woman with rubella infection commonly present?
With rash, arthritis, and lymphadenopathy
How does a pregnant woman with syphilis commonly present?
If primary, with chancres; if secondary, with disseminated rash; if tertiary, with
cardiac and neurologic symptoms
Name eight diseases that can cause red rashes in childhood.
Measles, mumps, rubella, roseola (human herpesvirus type 6), scarlet fever (group
A strep), parvovirus B19, varicella zoster virus, Coxsackie A
Describe the rash associated with scarlet fever.
Red and sandpaper-like (accompanied by fever and sore throat)
What is hand-foot-and-mouth disease?
Vesicular lesions on the extremities and oral mucosa caused by coxsackie A virus
How does gonorrhea present in men and women?
In both, urethritis with creamy purulent discharge; in women, cervicitis, pelvic
inflammatory disease; in men, prostatitis, epididymitis; disseminated disease can
cause migratory arthritis and skin pustules
How do the lesions of chickenpox differ from those of smallpox?
In chickenpox the lesions are in various stages of healing; in smallpox all lesions
are of the same age
A 2-year-old patient has a high fever for 3 days. On the fourth day, the temperature
returns to normal, but the child develops a body-wide red rash. What is the
diagnosis?
Human herpesvirus type 6
Characterize the disease caused by Chlamydia trachomatis(serotypes D-K).
Urethritis, cervicitis, pelvic inflammatory disease; neonates can develop
conjunctivitis; susceptible individuals can develop reactive arthritis (Reiter
syndrome)
How does the presentation of measles differ from that of rubella?
Measles is preceded by cough, coryza, conjunctivitis and Kopliks spots whereas
rubella has a notable postauricular lymphadenopathy
What organism causes lymphogranuloma venereum?
Chlamydia trachomatisserotypes L1 through L3
What are the findings of lymphogranuloma venereum?
Ulcers, lymphadenopathy, and rectal strictures
What spirochete causes a painless chancre?
Treponema pallidum (primary stage)
What are the findings of secondary syphilis?
Fever, lymphadenopathy, condyloma lata, and skin rashes
What are the clinical findings in tertiary syphilis?
Tabes dorsalis, gummas, aortitis, Argyll Robertson pupil
What disease is caused by Haemophilus ducreyi?
Chancroid, characterized by painful, genital ulcers and inguinal lymphadenopathy
(remember: Haemophilus ducreyi so painful, you do cry)
In addition to painful genital lesions, herpes simplex virus type 2 commonly causes
what systemic symptoms?
Headaches, fevers, myalgias
Trichomonas vaginaliscauses what condition in women?
Vaginitis; unlike other etiologies of vaginitis, trichomonas is sexually transmitted
What causes condyloma acuminata?
Human papillomavirus types 6 and 11
Which viral hepatitis can be sexually transmitted?
Hepatitis B
What three findings are indicative of bacterial vaginosis?
Noninflammatory discharge, fishy odor (positive whiff test), and clue cells on
microscopy
Pelvic inflammatory disease is most often caused by what two organisms?
Chlamydia trachomatis and Neisseria gonorrhoeae
What is the most common sexually transmitted disease in the United States?
Chlamydia trachomatis; unlike gonorrhea it can be an asymptomatic infection and
therefore has higher prevalence
Cervical motion tenderness is most commonly associated with what disease?
Pelvic inflammatory disease due to ascending chlamydial or gonorrheal infection
What is the chandelier sign?
Cervical motion tenderness; said to be so painful that the patient jumps up to the
ceiling (the chandelier)
Name four possible sequelae of pelvic inflammatory disease.
Salpingitis, endometritis, hydrosalpinx, and tubo-ovarian abscess
Salpingitis is a risk factor for which complications?
Adhesions, which lead to ectopic pregnancy, infertility, and chronic pelvic pain
What cause of vaginitis shows motile organisms on wet preparations?
Trichomonas vaginalis
How does the presentation of urethritis due to gonorrhea differ from that due to
chlamydia?
Neisseria gonorrhoeae often causes acute disease with high fevers
What is Fitz-Hugh-Curtis syndrome?
Ascending gonorrheal or chlamydial infection causing inflammation of the liver
capsule and “violin string” adhesions of the parietal peritoneum to the liver
Cytomegalovirus and respiratory syncytial virus are often associated with
transmission in what nosocomial setting?
The newborn nursery
Which two pathogens are most likely to cause nosocomial infections associated
with urinary catheterization?
Escherichia coli and Proteus mirabilis
Which nosocomial infection can cause blue-green pus to develop in burn wounds?
Pseudomonas aeruginosa
(remember:
presume Pseudomonas AIRuginosa when AIR or burns are involved)
What etiology of pneumonia, uncommon outside of cystic fibrosis patients, can be
acquired from respiratory therapy equipment?
Pseudomonas aeruginosa(remember: presume Pseudomonas AIRuginosa when AIR or burns are involved)
Hepatitis B virus is associated with nosocomial infections in what setting?
The renal dialysis unit, due to the frequency of venipuncture in that setting
What organism is associated with infection of intravenous lines used for
hyperalimentation?
Candida albicans
Water aerosols that lead to nosocomial infections often involve which organism?
Legionella(remember: think Legionella when water sources are mentioned)
What are the two most common causes of nosocomial infections?
Escherichia coli(urinary tract infection) and Staphylococcus aureus (wound infections)
How do HIV-positive adults with Histoplasma capsulatuminfection present?
Low-grade fever, cough and hepatosplenomegaly; immunocompetent individuals
would have only pulmonary symptoms, if any
How do HIV-positive adults with Candida albicans infection commonly present?
With fluffy, cottage-cheese lesions on the buccal mucosa (thrush)
What is bacillary angiomatosis?
Vascular proliferation with neutrophilic inflammation seen in HIV-positive
individuals infected with Bartonella
What is Kaposi sarcoma?
A malignant neoplasm of superficial vascular endothelial cells caused by human
herpesvirus type 8 in HIV-positive individuals
How does the superficial vascular proliferation of Kaposi sarcoma differ from
bacillary angiomatosis histologically?
Bacillary angiomatosis is marked by neutrophilic inflammation whereas Kaposi
sarcoma is a malignant neoplasm with lymphocytic inflammation
How does an HIV-positive adult with Cryptosporidiuminfection commonly
present?
With chronic, watery diarrhea
What finding in the stool suggests Cryptosporidiuminfection?
Acid-fast cysts
Which yeast commonly causes meningitis and encephalitis in adults who are HIV
positive?
Cryptococcus neoformans
What causes progressive multifocal leukoencephalopathy?
In AIDS patients, latent JC virus reactivates and causes demyelination
What diagnosis should be considered in an HIV-positive patient found to
have cotton wool spots on fundoscopic exam?
Cytomegalovirus retinitis
