Chapter 3 - Principles of Infectious Disease and Fever in Acute Care Flashcards
Basic bacterial cell properties
- bacteria are their own organism
- unlike human cells that have a cell membrane, bacterial cells have a cell wall
- dependent on protein synthesis and DNA replication
Basic viral cell properties
- viruses must utilize a human host
- virus attaches to the cell membrane and injects nucleic acid (DNA or RNA) into the cell → virus nucleic acid replication using host → new viruses and destruction and host cell
3 primary targets of antibiotics
- the cell wall, “bactericidal”
- bacterial protein synthesis, “bacteriostatic”
- bacterial DNA replication, “bacteriostatic”
2 main properties of antivirals
- block entry of virus into host cell (ex: antiviral prophylaxis)
- work in the host cell to deactivate the virus
Normal WBC count
4,000-11,000
The WBC Differential: Neutrophil
- role: destroy bacteria
- normal range: 57-67%
The WBC Differential: Lymphocytes
- role: destroy viruses
- normal range: 22-33%
The WBC Differential: Monocytes
- role: clear cellular debris
- normal range: 3-7%
The WBC Differential: Eosinophils
- role: combat allergens/parasites
- normal range: 1-3%
The WBC Differential: Basophils
- role: undetermined, role in anaphylaxis
- normal range: 0-1%
The WBC Differential: Bands (immature neutrophils)
- 3-5% of total neutrophils count
- bands are like teenagers: if you see a large number congregating somewhere, something bad is happening (> 10% bands)
Non-infectious causes of fever
- Autoimmune
- Inflammatory
- Drug reaction
Infectious causes of fever
- Bacterial (most common cause of fever in acute care setting)
- Viral
- Fungal (more common in immunocompromised patients)
- Rickettsial
- Parasitic
Most common causes of post-op fever
- volume contraction (dehydration)
- atelectasis
Bacterial post-op fever
Common findings • Fever • Leukocytosis with neutrophilia • Surgical site drainage Diagnostic workup • Evaluate for point of invasion • Blood cultures • Wound cultures • UA with culture Treatment • ANTIBIOTICS ONLY WITH SIGNS OF BACTERIAL INFECTION • Remove offending items (Foley, lines, etc.)
Volume contraction (dehydration) post-op fever
Common findings
• Azotemia
• Decreased skin turgor (except in elderly)
• Decreased PO intake/inadequate IV hydration
Diagnostic Workup
• Metabolic panel
• Determine estimated blood loss and replacement
• Evaluate intake and output
• Urine output = most reliable indicator of perfusion
Treatment
• Isotonic IV fluids and increase PO fluid intake
Atelectasis post-op fever
Common findings • Atelectasis present on CXR • Lack of incentive spirometer use • Cough • SOB • Decreased lung sounds Diagnostic workup • Evaluate use of incentive spirometer • Diagnosis of exclusion • May consider a CXR Treatment • Encourage incentive spirometer • OOB to chair and ambulation • Educate on splinting • Evaluate medication use that decrease respiratory drive (i.e., narcotics)
Risks vs. benefits of fever: Risks
- Doubles caloric requirement
- Increases myocardial O2 requirement by 15%
- Uncomfortable
- Inhibits mobility
- Teratogenic (harmful to fetus)
- Rapid elevation → seizure (most common in children)
Risks vs. benefits of fever: Benefits
- Kills or reduces replication in most infectious organisms
- Enhances the inflammatory response
- Improved outcomes and survival in animal studies and pediatrics
Contraindications to Fever
- Myocardial disease – ↑ myocardial O2 requirements
- Pregnancy – teratogenicity of fever
- Elderly (caution) – double caloric requirements in those already at risk for malnutrition
General Principles on Treatment of Fever
- Antibiotics only when evidence of bacterial infection is present (neutrophilia, drainage, positive cultures)
- Antibiotic therapy starts with broad spectrum (based on likely cause of infection) and then narrow spectrum (based on culture results)
- Antipyretics only when metabolic costs of fever outweigh risks
- If the patient can tolerate the fever, consider lowering the temperature vs. eliminating the fever completely
Common symptom complex of a UTI
- dysuria
- urgency
- frequency
Complicated UTI/pyelonephritis vs. uncomplicated UTI
complicated UTI/pyelonephritis is positive for CVA tenderness, fever, nausea, and/or vomiting
Diagnostic workup for an uncomplicated
Consider a UA with culture and susceptibilities
Diagnostic workup for a complicated UTI/pyelonephritis
- UA with culture and susceptibilities
- CBC and blood culture
Outpatient treatment of an uncomplicated UTI
- TMP-SMX (bactrim) DS 1 tab PO twice daily for 3 days (if local resistance < 20%)
- Nitrofurantoin (Macrobid) 100 mg PO twice daily for 5 days (if sulfa allergy or local resistance to TMP-SMX > 20%)
Outpatient treatment of a complicated UTI/pyelonephritis
- Ciprofloxacin 500 mg PO twice daily or 1000 mg PO daily for 5-7 days or levofloxacin (Levaquin) 750 mg PO daily for 5-7 days
- Ceftriaxone (Rocephin) 1g IM (if local fluroquinolone resistance is > 10% or patient can’t take fluroquinolones)
Inpatient treatment of complicated UTI/pyelonephritis
- Ciprofloxacin 400 mg IV twice daily or levofloxacin (Levaquin) 750 mg IV daily for 5-7 days
- alternative regimens: 3.375 mg IV q4-6h for 14 days
Re-evaluation of UTI
- if patient doesn’t respond to initial duration of therapy, continue for a 2 week course
- if patient fails 10-14 days of outpatient therapy, hospitalize for further evaluation and order IV antibiotics or continue PO regimen for 4-6 weeks
CAUTI diagnostics
- CBC, UA with C&S, blood cultures
CAUTI treatment
- remove catheter and evaluate for obstruction
- ampicillin + gentamicin or zosyn 3.375 mg IV q4-6h (duration varies)
- doripenem (Dobrax) 500 mg IV q8h
- imipenem (Primaxin) 0.5g IV q12h
- meropenem (Merrem) 1g IV q8h
- alternative therapies: ciprofloxacin or levofloxacin as indicated for pyelonephritis (duration varies)
Cellulitis types
- steptococcus pyogenes (Groups A, B, C, & G) aka non-purulent
- staphylococcus aureus (MRSA) aka purulent
Treatment for non-purulent cellulitis
- duration: 7-10 days
- dicloxacillin 250-1000 mg PO QID
- cephelexin (Keflex) 500 mg PO QID (if hx of PCN-related, non-IgE mediated skin rash)
Outpatient treatment for purulent cellulitis
- duration: 7-10 days, longer for chronic disease
- TMP-SMX (bactrim) DS 1-2 tabs PO twice daily (MRSA)
- clindamycin
- doxycycline 100 mg PO twice daily (MRSA)
Inpatient treatment for purulent cellulitis
- TMP-SMX (bactrim) DS 1-2 tabs PO twice daily (MRSA)
- clindamycin
- doxycycline 100 mg PO twice daily (MRSA)
- vancomycin 1g IV q12h (MRSA) (trough concentration goal is 15-20 mcg/ml)
Risk factors for MRSA
- recent hospitalization
- LTC facility
- recent antibiotic therapy
- incarceration
- injection drug use
- diabetes
- HIV
- *if a patient has a risk factor, generally will treat as if they already have MRSA until proven otherwise
Diagnostic findings of C. difficile
- profuse, watery, foul-smelling diarrhea
- positive C. difficile stool culture
Risk factors for C. difficile
- ANTIBIOTIC USE (clindamycin is well known to cause this)
- direct exposure to another person with C. difficile
Classification of C. difficile infection
Mild - WBC < 15,000 - no increase in serum creatinine Moderate - WBC > 15,000 - OR - - > 50% increase in serum creatinine Severe - WBC > 15,000 - OR - - > 50% increase in serum creatinine - OR - - Zar score ≥ 2
Treatment for C. difficile depending on classification
Mild - vancomycin 125 mg PO BID x 10 days Moderate - vancomycin 125 mg PO QID x 10 days Severe - vancomycin 500 mg PO q6h + metronidazole (Flagyl) 500 mg IV q8h -- toxic megacolon -- colectomy
General info about HIV
- transmitted via sexual, parenteral, and vertical transmission
- flu-like syndrome weeks after initial viral acquisition and infection
HIV: ELISA vs. Western Blot
- ELISA SCREENS with > 99% sensitivity (screening, cheaper)
- Western Blot CONFIRMS to 99.8% specificity (for confirmation)
SeNsitivity vs. SPecificity
- SeNsitivity: if test is highly sensative and Negative = rules out
- SPecificity: if test has high specificity and Positive = confirms disease
CD4 count vs. viral load with HIV
- CD4 count indicates level of functional immunity; used to INITIATE therapy
- Viral load measure viral replication; used to TITRATE therapy
When to initiate antiretroviral treatment for HIV
- recommended for all HIV-infected individuals regardless of CD4 count to reduce risk of disease progression
What is Pre-Exposure Prophylaxis (PrEP)?
Use for individuals who do not have HIV but are at high risk of being infected
Who should be considered for PrEP?
Those without HIV who are at very high risk from sex or injection drug use
When to start PrEP?
ASAP following a risk behavior assessment and lab testing confirms absence of HIV
What is the duration of PrEP?
Daily treatment should continue until risk becomes low d/t less risk exposure
What is Post-Exposure Prophylaxis (PEP)?
Use after a single high-risk event to minimize possibility of HIV infection
Who should be considered for PEP?
Those without HIV who are at high risk of HIV acquisition through isolated exposure within past 72 hours
When to start PEP?
ASAP following the event and always within 72 hours of possible exposure
What is the duration of PEP?
28 days
A 54-year-old male is post-op day #1 following lumbar spine surgery secondary to MVC. The patient is receiving isotonic fluids at 80 ml/hr. A Foley catheter is in place for neurogenic bladder and draining clear, dark yellow urine at an output rate of 25 ml/hr. The nursing staff pages you to report that he has a temperature of 100.5F (38C). Appropriate management include (select all that apply):
a. Order a PRN antipyretic for a temperature > 100F (37C)
b. Encourage incentive spirometry use 10x per hour
c. Increase isotonic IV fluids to 125 ml/hr
d. Begin a third-generation cephalosporin antibiotic
e. Discontinue the Foley catheter order
b. Encourage incentive spirometry use 10x per hour
c. Increase isotonic IV fluids to 125 ml/hr
A 26-year-old female is post-op day #2 from a hernia repair. The nurse calls you to the bedside and is concerned about infection since the patient has a temperature of 100.6F (38.1C). Which of the following findings is most consistent with bacterial wound infection?
a. Pain at the incision site
b. Azotemia
c. Anorexia
d. Neutrophilia
d. Neutrophilia
A 64-year-old male with a 40 pack-year smoking history presents for a follow-up visit 8 days after a carotid endarterectomy. He feels well but reports a “knot” at the incision. You palpate a hard induration approximately 1 cm wide along both sides of the entire incision line. There is no erythema, edema, or drainage; the patient is afebrile. What is the most likely diagnosis?
a. Surgical wound abscess
b. Hematoma
c. Keloid
d. Healing ridge
d. Healing ridge
The AGACNP is performing an incision and drainage on a simple, fluctuant abscess. Which of the following steps of the procedure are critical to ensuring the complete resolution of this abscess (select all that apply):
a. Performing deep penetration through the crown of the abscess
b. Administering an injectable anesthetic agent prior to the procedure
c. Exploring the wound to break up loculations
d. Antimicrobial therapy for 5-7 days following the procedure
e. Copious irrigation of the wound
a. Performing deep penetration through the crown of the abscess
c. Exploring the wound to break up loculations
e. Copious irrigation of the wound
B is not correct because while this is nice, it is not “critical”
A 75-year-old female patient is admitted to the hospitalist service with a fever of 101.5F (38.6C), which you initially assume is probably the result of a UTI. Laboratory evaluation of the patient reveals a total WBC count of 7,800, a erythrocyte sedimentation rate (ESR) of > 110 mm/h, and a UA revealing clear, yellow urine with the absence of leukocytes and nitrates. Her past medical history is significant for HTN and dyslipidemia. She reports that she has also been taking an OTC pain medication to treat her headaches occurring on a daily basis. What is the most likely differential diagnosis?
a. An infectious process but the patient is unable to mount a WBC count d/t her age
b. Giant cell arteritis
c. Endocarditis
d. Drug fever d/t the high incidence of polypharmacy in the over 65 population
b. Giant cell arteritis
A 62-year-old male patient with HTN presents to the ED with persistent fevers ranging from 101.3F (38.5C) to 102.9F (39.4C) for the last 5 days. His home medications include nifedipine (Procardia), pantoprazole (Protonix), and HCTZ (Microzide). Blood and urine cultures are negative, and a CXR reveals no acute cardiopulmonary process. The total WBC is 6,500. Which of the following is the most likely cause of his fever?
a. Drug reaction
b. Viral infection
c. Inflammatory disease
d. Malignancy
a. Drug reaction
A 42-year-old female presents with dysuria and subsequently diagnosed with a UTI. The patient denies hematuria and on physical exam, there is no flank tenderness. Which of the following treatment regimens would be most appropriate?
a. Nitrofurantoin (Macrobid) 100 mg PO twice daily for 5 days
b. Ciprofloxacin (Cipro) 250 mg PO twice daily for 10 days
c. TMP-SMX (Bactrim DS) 1 tap PO twice daily for 7 days
d. Levofloxacin (Levaquin) 250 mg PO daily for 5 days
a. Nitrofurantoin (Macrobid) 100 mg PO twice daily for 5 days
B is not correct: fluroquinolones are not first line and suggested regimen is too long
C is not correct: regimen is too long
D is not correct: fluroquinolones are not first line
Which of the following findings on a UA report are most consistent with a UTI (select all that apply):
a. Positive leukocyte esterase
b. Increase squamous cells
c. Increased WBCs
d. Positive nitrates
e. Increased RBCs
a. Positive leukocyte esterase
c. Increased WBCs
d. Positive nitrates
A 54-year-old patient is POD #4 following an open cholecystectomy. While reviewing the patient’s chart the AGACNP notes a T-max of 101.3F (38.5C) and a WBC of 15,000. Upon physical exam, the surgical wound site has no signs of infection and a Foley catheter is noted draining cloudy, yellow urine. A UA dipstick is positive for leukocyte esterase and nitrates with > 10 WBC/hpf. What is the most appropriate first-line treatment?
a. Piperacillin-tazobactam (Zosyn) 3.375g IV q4h
b. Ciprofloxacin (Cipro) 500 mg IV q6h
c. Levofloxacin (Levaquin) 750 mg IV q12h
d. Cephalexin (Keflex) 500 mg IV qh
a. Piperacillin-tazobactam (Zosyn) 3.375g IV q4h
B and C are not correct: fluoroquinolones are alternatives for CAUTIs, not first-line
The ACACNP is evaluating a 45-year-old female patient from a local prison who is subsequently diagnosed with cellulitis. The patient is afebrile and the plan is to discharge the patient with outpatient treatment. Which of the following antibiotics is most appropriate for the AGACNP to prescribe for this patient?
a. Cephalexin (Keflex) 500 mg PO 4x daily
b. Penicillin V-K (Pen-VK) 500 mg PO 4x daily
c. TMP-SMX (Bactrim) 1tab PO twice daily
d. Vancomycin 1g PO twice daily
c. TMP-SMX (Bactrim) 1tab PO twice daily
C is correct because: patient is incarcerated = risk for MRSA → treat for MRSA
A 34-year-old male patient is diagnosed with cellulitis that is suspected to be non-MRSA in nature. The patient reported that he “gets a skin rash” when he take penicillins but previous allergy testing found this is not an IgE-mediated reaction. What would be the best choice of antibiotic therapy for this patient?
a. Cephalexin (Keflex) 500 mg PO 4x daily
b. Azithromycin (Zithromax) 500 mg PO x1 dose then 250 mg PO daily
c. Clindamycin (Cleocin) 450 mg PO 3x daily
d. Linezolid (Zyvox) 600 mg PO twice daily
a. Cephalexin (Keflex) 500 mg PO 4x daily
In addition to antibiotic therapy, the AGANCP should educate the patient on which of the following?
a. Keep the leg elevated
b. Compress the leg with ACE wraps
c. Bathe the leg daily in a hydrogen peroxide solution
d. Fever should resolve within 12 hours of starting antibiotics
a. Keep the leg elevated
Which of the following patients is at highest risk for Clostridium difficile infection?
a. A 73-year-old patient residing in the same hospital room as another patient with positive C. difficile cultures
b. A 24-year-old patient who just completed 3 days of azithromycin (Zithromax) therapy and developed diarrhea that resolved without treatment in 48 hours
c. A 20-year-old patient prescribed a 10-day course of levofloxacin (Levaquin)
d. A 60-year-old transplant patient on antifungal prophylaxis with fluconazole (Diflucan)
c. A 20-year-old patient prescribed a 10-day course of levofloxacin (Levaquin)
C is correct because: there is direct antibiotic exposure
A is incorrect: while this is a risk factor, less likely than direct antibiotic exposure
A 50-year-old female patient is POD #10 following a hepatic resection secondary to metastatic colon cancer. She has been on several antibiotics due to surgical wound infections and has now developed profuse watery, foul-smelling diarrhea. What is the most appropriate initial action for the AGACNP to perform?
a. Order stool cultures for C. difficile
b. Order diphenoxylate and atropine (Lomotil)
c. Change her diet order to high protein with low residue
d. Ensure adequate IV fluid replacement
a. Order stool cultures for C. difficile
A 45-year-old male patient is diagnosed with C. difficile infection. The AGACNP notes a WBC of 30,000 and a serum creatinine of 1.6 mg/dL (baseline creatinine is 0.6 mg/dL). The patient is tolerating an oral diet well. What is the most appropriate antibiotic regimen?
a. Metronidazole (Flagyl) 500 mg IV q6h
b. Vancomycin 1g IV twice daily
c. Metronidazole (Flagyl) 500 mg PO 3x daily
d. Vancomycin 125 mg PO 4x daily
d. Vancomycin 125 mg PO 4x daily
A patient is requesting random HIV testing. The patient’s ELISA screen is positive and the Western Blot is negative. The AGACNP provides which interpretation?
a. The patient is HIV negative
b. The patient is HIV positive
c. The patient requires repeat testing in 6 weeks
d. The patient is negative unless an opportunistic infection develops
a. The patient is HIV negative
A is correct because: ELISA screens for more than just HIV and can be positive for other reasons but a negative Western Blot is confirmatory
The AGACNP is caring for a 15-year-old female patient who had unprotected sexual intercourse 5 days ago and presents for HIV testing after finding out her male partner is HIV positive. The patient has a negative ELISA screening. What is the most appropriate response by the AGACNP?
a. “You do not have HIV”
b. “You will require follow-up testing in 6 weeks”
c. “You will need to have a parent/guardian sign a release for the results”
d. “We can start you on prophylactic antiviral therapy now”
b. “You will require follow-up testing in 6 weeks”
B is correct because: Can sometimes take up to 2 weeks to seroconvert and cause the ELISA to pop positive
D is incorrect: Should be started at maximum 72 hours after exposure
A patient is requesting random HIV testing. The patient’s ELISA screen is positive and the Western Blot is indeterminate. The AGACNP provides which interpretation?
a. The patient is HIV positive
b. The patient is HIV negative
c. The patient requires repeat testing in 6 weeks
d. The patient is negative unless an opportunistic infection develops
c. The patient requires repeat testing in 6 weeks
