Infectious Disease Flashcards
Osteomyelitis and Septic Arthritis
Cellulitis and Abscess
Necrotizing Fascitis
Phlegmon
Diffuse cellulitis w/ WBC w/o a discrete focus
“Pre-abcess”
Septic Joint
Bacterial infection in the joint
Osteomyelitits
Infection of bone, joint, or cartilage
What is the difference between Cellulitis and Venous insufficiency?
- Cellulitis
- Acute
- Unilateral
- can cross Joints
- Acute
- Venous insufficiency
- Chronic
- Bilateral
- Doesn’t cross joints
- Limited to legs
- Looks infected but no fever or leukocytosis
What is the treatment for an abcess <2.5 cm? >4.5 cm?
<2.5 cm = Antibiotics
>4.5 cm = MUST be drained!!
Erysipela
- Characteristics
- Cause
- Characteristics:
- Form of cellulitis
- present on both sides of the face
- crosses the bridge of the nose
- Spares the globe of the eye
- Can move the eyes
- Cause:
- Strep pyogenes (Group A) >> S. agalactiae (Group B strep)
Who is most commonly affected by necrotizing fascitis?
Immune compromised patients
(Diabetics / Dialysis)
Necrotizing Fascitis
- Characteristics
- Method of progression of infection
- Characteristics
- Cellulitis dissecting along fascia
- Associated with diabetes and lack of blood flow
- Method of progression of infection
- Ascending toxin kills blood supply
What is Fornier’s gangrene?
Peri-genital Necrotizing Fascitis
What are the characteristics of each stage of wound?
- Stage 1
- Stage 2
- Stage 3
- Stage 4
- Stage 1
- Develop ischemia
- prolonged pressure = no blood flow
- No ulceration
- Develop ischemia
- Stage 2
- into skin
- Stage 3
- into subcutaneous tissue
- Stage 4
- into muscle
What is the function of biofilm? How do cells on the inside communicate with those on the outer borders?
- Function
- Increases resistance to Abtx
- Communicate by quorum sensing
What is the most common cause of Osteomyelitis?
Staph aureus
What is Wagner’s Classification for Diabetic Ulcers?

Time dependent vs Concentration dependent Killing (Antibiotics)
- Time dependent
- Effective due to extensive time bound to organism
- optimal response
- time drug remains above the MIC is equal or greater than 50% of the dosing interval
- Concentration dependent
- Effective due to high concentrations at the binding site
- Optimal Response
- Concentration is 10-20x MIC
Jane is a 55 yo WF who reports that she suddenly developed a rash on her face 24 hrs ago. She describes it as hot, red, tender and spreading around her nose onto both cheeks, but R>L side. Temperature is 101.2 and HR is 120. WBC is 13K.
•Which of the following statements is not true?
A)This is cellulitis
B)This is Erysipelas
C)It is most commonly caused by Group A Streptococcus
D)Necrotizing Fasciitis is a common complication
D
Elmer is a 63 yo diabetic postal worker who presents with a hot, red, swollen left knee that has progressively gotten worse over the past 2 weeks.
Which of the following statements is not true?
A)Staphylococcus aureus is the most common cause
B)Cartilage is destroyed by the toxins made by the bacteria
C)The blood flow in cartilage allows good drug delivery
D)If a prosthetic joint is present, then it is typically removed during the course of 6 weeks of IV antibiotics.
C
Sepsis and Endocarditis
What is SIRS?
Systemic Inflammatory Response Syndrome
- Vasodilation
- Leukocyte accumulation
- Increased vasc. permeability
- Non-infectious insult
- Uncontrolled pro - inflammatory release
What is Bacteremia?
Bacteria in the blood
What is Moderate Sepsis?
- End - organ dysfunction
- Correctible
- Lactate >2
What is severe Sepsis?
- 2 organ dysfunction
- Not correctible
- Lactate >4 mmol/L
***Need to pounded w/fluid (1L/hr)
What is septic shock?
- Same as above but with DIC
- At least one other organ dysfunction
- Persistent HypoTN despite fluid resuscitation
Treatment:
- Blood cultures before antibiotics
- Lactate before 90 minutes
- IV antibiotics before 180 minutes
- 3cc/kg of IV fluids before 180 minutes
What are the causes of endocarditis?
HACEK Group
- Haemophilus (NOT Influenza)
- Actinobacillus
- Cardiobacterium
- Eikenella
- Kingella
Sepsis can cause Endocarditis
Right Sided Endocarditis
- Causes
- IV Drug abuse
- Dialysis
- Signs
- “a new murmur is heard”
- Treatment is shorter than for L sided if due to IVDA
Risk of emboli to lungs
Left Sided Endocarditis
- Causes
- S. aureus
- HACEK
-
Dental source
- “patient had his teeth cleaned 2 mo ago” is a classic Q
- Symptoms
- Janeways lesions
- Osler’s nodes
- Splinter hemorrhages (nail bed)
- Treatment
- 6 wks
Stroke risk
45 yo male with history of DM, ESRD on Hemodialysis presents with 5 day history T 101.8, hypotension 88/62 despite 3 L NS, creat 5.8 (baseline 5.0), and HR 122. Lactate is 4.2
Which of the following is not true:
- This patient has severe sepsis
- Since he is stable, he does not need ICU care
- A cardiac echo is indicated to look for endocarditis
- If the dialysis catheter site looks OK, it can initially be left in place.
2
A 28 yo female presents to the ER with hx of fever 101, cough, weakness, myalgia, and rigors. Evaluation demonstrates WBC 14K, X ray with bilateral patchy infiltrates, HR 98, BP 110/68, and normal renal function. Lactate 2.5. Examination demonstrates a (new) 4/6 murmur present on the R 4th intercostal space. Needle tracts are found in the antecubital fossa bilaterally.
Pick the true statement
1.This is most consistent with L-sided endocarditis
2.This is most consistent with R-sided endocarditis
3.This murmur is most likely from the Aortic Valve
4.The HACEK group include Haemophilus influenza, Acinetobacter and Klebsiella
5.This patient meets criteria for the ICU.
●
2: right sided murmur
New murmur
Needle tracts
Meningitis
Meningitis vs Encephalitis
- Meningitis
- Headache
- Normal CNS function
- Encephalitis
- Altered mental status
- Motor/Sensory deficits
- Behavioral neurologic features
Meningitis Lumbar Puncture
- Elevated CSF
- Opening pressure often high
- Protein of 100-500 mg/dL
- Glucose <40 mf/dL
- Gram stain
Bacterial Meningitis causes
- Gp A strep
- Gp B strep
- Streptococcus pneumonia
- Haemophilus influenza
- Neisseria influenza
- MRSA
- Listeria
Viral Meningitis Causes
- Picornavirus
- HSV
- HIV
- West Nile Virus / Arbovirus
- Mumps
- Lymphocytic choriomeningitis virus
Neonatal HSV encephalitis is caused by which virus?
HSVII
Necrosis of temporal lobes is characteristic of what type of meningitis?
HSV
Labs in Mumps
- <500 wbc/uL Lymphocytes
- Protein slightly elevated or normal
- Glucose depressed
West Nile Encephalitis
- Symptoms
- Fever
- Back pain/myalgia
- Flaccid paralysis
- Seizures
- Nerve palsy
Fungal Meningitis
- Risk factors
- Causes
- Risk factors:
- HIV/AIDS
- Lymphoma
- Steroids
- Anti-TNF
- Diabetes
- Causes
- Aspergillus
- Zygomycetes
74 yo WF presents to the ER brought in by family with confusion with a history of 2 days of low grade temp, then spike to 102.4 today. Confusion started today, with bizarre behaviors and irritability. Non-compliant with exam, with episodes of lethargy. Possible meningismus. HR 102, BP 120/77. Labs are all normal.
LP reveals 440 WBC with 77% lymphocytes and 23% neutrophils and no organisms seen.
Which of the following is not true:
- CSF should be sent for HSV PCR
- This is Encephalitis
- MRI scan will likely show Temporal Lobe involvement
- This is Meningitis
4
Common lumbar puncture (LP) findings in bacterial meningitis include which of the following:
- WBC 400 with 77% neutrophils, glucose 34, Protein 200
- WBC 4, glucose 100, protein 64
- HSV PCR positive for HSV II
1 = meningitis
3 = encephalitis
_ STDS_
What is the most commonly reported STD in the US?
Chlamydia
Woman presents with drip, burning, and abdominal pain with PID. What STD does she have?
Chlamydia
Man presents with discharge, burning, and possible epididymitis. What STD does he have? What is the most common presentation?
Chlamydia
Normally asymptomatic
What complications are associated with Chlamydia?
- PID
- Lymphogranuloma venereum
- Reiter’s syndrome in males
- Reactive arthritis
- Uveitis
- Urethritis
Green, white, or yellow penile drainage is characteristic of which STD?
Gonorrhea
How is Hep A transmitted?
Fecal-oral route
NOT an STD
Herpes Simplex Virus causes what types of ulcerations?
Oral and genital
What strains of HPV cause Genital Warts?
6 or 11
When can invasion of the CNS occur in syphilis?
At any stage
A painless chancre with regional lymphadenopathy is characteristic of which STD?
Primary Syphilis
Treponema Pallidum
Palmar/Plantar Rash, such as Stevens Johnson syndrome and Hand Foot and Mouth disease, are characteristic of which STD?
Secondary Syphilis
T. pallidum
Condylomata lata are characteristic of which STDs?
Secondary Syphilis
HPV
Nickel/Dime Lesions and Alopecia are characteristic of which STD?
Secondary Syphilis
Gummatous lesions and cardiovascular symptoms are characteristic of which STDs?
Tertiary Syphilis
Hutchinson’s Teeth is characteristic of which STD?
Congenital syphilis
When is transmission of syphilis to fetus most common?
Primary and secondary syphilis
any trimester for fetus
Urethritis with itching, burning, and thin discharge is caused by which STD (Parasite)?
Trichomoniasis
What is the only protozoan that infects the genital tract? With what is it associated?
Trichomonas vaginalis
- Associations
- Preterm rupture of membranes and delivery
- Increased risk of HIV
Strawberry cervix is characteristic of which STD?
T. vaginalis
How is T. vaginalis diagnosed in women?
- Women
- Culture***
- Pap smear works too if using liquid based testing
Sex partners of women diagnosed with T. vaginalis should also be treated regardless of initial testing
Which of the following statements are not true about Chlamydia?
- Reiter’s syndrome (reactive arthritis, uveitis, and urethritis) is associated with Chlamydia.
- Most cases are asymptomatic
- Major cause of PID and infertility
- A Serovar type (subtype) is the cause of Lymphogranuloma venerium
- Can cause osteomyelitis
5
Which of the following statements concerning STDs is not true?
- The most commonly reported STD is Chlamydia trachomatis
- Trichomonas is a protozoan that only infects humans
- HSV 2 is more likely than HSV 1 to cause meningoencephalitis
- Gonorrhea presents with a painless chancre
4
Abdominal Infxn
Diarrheal Infxn
Hemolytic Uremic Syndrome
Causes of Diverticulitis /Typhlitis
- Staph aureus
- Enterococcus
- Bacteroides
- Pseudomonas
- Candida
Causes of Bloody Diarrhea
- Salmonella
- Shigella
- Yersinia
- Campylobacter
- E coli 0157:H7
Bloody diarrhea and post infectious arthritis are characteristic of what infection?
Salmonella
Poultry, Turtles
By what is Salmonella is transmitted?
Poultry
Turtles
By what is Shigella transmitted?
Pork
Bloody diarrhea with skin rash and arthritis (post infectious) is characteristic of infection by what?
Yersinia
Pork, Raw Milk
What is the most common food-borne illness in the USA?
Campylobacter
What cause of bloody diarrhea also causes Guillain Barre?
Campylobacter
What are the most common causes of E. coli 0157:H7 infection?
- Water (drinking or swimming)
- Beef
Causes Bloody Diarrhea
Bloody diarrhea with no fever is caused by what?
E. coli 0157:H7
Has shiga toxin
Why should E. coli 0157:H7 not be treated with Antibiotics?
Increases the risk for HUS
Hemolytic Uremic Syndrome (HUS)
- Cause
- Symptoms
- Cause
- EHEC infxn
- Symptoms
- Acute Renal Failure
- Microangiopathic Hemolytic Anemia
- Thrombocytopenia
Is probiotic use to prevent C Diff infxn indicated?
No
No data
May cause blood infxn
C. Diff
- Disease requirements
- What causes increased risk of
- Recurrent CDI
- Severe CDI
- Disease requires
- Colonization or spore
- Antibiotic to perturb gut flora
- What causes increased risk for recurrent CDI?
- Prolonged hospitalization
- What causes increased risk for severe CDI?
- Max WBC count > 20,000 cells/mL
Foodborne illness is very common in the US. Pick the mismatch pair:
- Shigella-Fecal-Oral route
- Salmonella-Poultry
- Yersinia-pork products
- Enterohemorrhagic E coli-Traveler’s diarrea
4
Which of the following statements is not true about Clostridium difficile enterocolitis?
- Pseuomembranes seen on colonoscopy
- Recurrent C. diff associated with decreased colonic flora diversity and malabsorption
- Extended metronidazole is associated with neuropathy
- Metronidazole is indicated for initial case associated with acute renal insufficiency
4
HIV
In HIV-1, what group is not detected by HIV testing?
Group O
What stage of HIV?
- CD4 counts >500 cells/uL or % total lymphocytes >29
Stage 1
What stage of HIV?
- CD4 counts 200-499 or % total lymphocytes = 14-28%
Stage II
What stage of HIV?
CD4 count <200 or % total lymphocytes < 14%
or
Documentation of an AIDS related condition
Stage III
What are the signs and symptoms of initial HIV infection?
- Acute Retroviral Syndrome
- Flu-like illness = “the worst ever”
- Lasts up to 3 months
- Symptoms
- Fever
- Chills
- Rash
- Night sweats
- Muscle aches
- Swollen lymph nodes
Kaposi sarcoma is more common in the US, likely due to higher rates of coinfection with what virus?
HHV8
What Pulmonary infxns are associated with AIDS?
- Candidiasis of RT
- Pulm TB
- Recurrent Pneumonia
What CNS infxns are associated with AIDS?
- PML orHIV encephalopathy
- Toxoplasmosis of brain
- Cryptococcosis of Brain
- CMV Retinitis
What GI infxns are associated with AIDS?
- Isoporiasis or Cryptosporidiosis
- MAC
What is the common cause of pneumonia in HIV population? What is the presentation?
Pneumocystis Jirovecii
- Presentation: Chronic, dry cough
When should treatment be initiated in HIV patients?
- CD4 count less than 350
- Any AIDS defining illness
- Pregnant women after 1st trimester
- HIV associate nephropathy
- Concomitant treatment of Hep B
A 34 yo WM presents with fever 102.4, severe headache of 4 days duration and neck stiffness. WBC is 12K with 65% PMNs. LP with opening pressure 320 mmHG, 360 WBC with 78% PMN. Cryptococcal Ag is +, with titre 1:128. HIV ELISA is +, and CD4 count is 282 (14.5%).
Which statement is true?
–Crytococcal meningitis can only be diagnosed if BC are positive as well.
–He has stage 2 HIV because the CD4 count is >200 and the CD4% is >=14.
–He has stage 3 HIV (AIDS)
He has stage 3 HIV (AIDS)
What is the viral load goal of antiretroviral therapy in pregnant women?
<1000
What is the most common cause of pneumonia at the initial time of presentation in AIDS patients??
a) Cryptococcus Pneumonia
b) Staph Aureus
c) Strep Pneumoniae
d) Pneumocystis Jirovecii
e) Pseudomonas Aeroginosa
D
A medical student gets a needle stick injury while learning how to suture in the operating room. What is his/her risk for HIV? When should treatment start?
- 1/3000
- 0.3%
- 3-4 hr
A medical student gets amniotic fluid from an HIV + source in his eyes while observing a C-section delivery. Risk for HIV? Treatment?
Risk is High
Treatment indicated
Ebola
What is the natural hosts of Ebola?
Fruit bats
What is the mechanism of transmission of Ebola?
Fecal - oral
How infectious is Ebola at each stage?
- Not infectious until person is symptomatic
- Most infectious in days following death
What is the mechanism of death in Ebola?
- Diarrheal disease
- Severe dehydraton
- Decreased electrolytes
- Cardiac dysfunction
What are the viral hemorrhagic fevers that occur naturally in the US?
- Hanta virus
- Dengue