IC1 & 3 Flashcards
Possible cause of superinfection
Antibiotic disrupts normal microbiota, causing bad bacteria to invade tissues
Systematic approach to using and monitoring antimicrobial therapy in patients
- Confirm presence of infection
- Identification of pathogen
- Selection of antimicrobial and regimen
- Monitor response
Identify subjective evidence that indicate the presence of an infection.
Localised symptoms
• Diarrhoea, nausea, vomiting, abdominal distension
• Cough, purulent sputum
• Dysuria, frequency, urgency
*Dysuria - pain or a burning sensation when you pee
• Pain and inflammation at site of infection – erythema, swelling, warmth
• Purulent discharge (wound, vaginal, urethral)
Systemic symptoms
• Feverish, chills, rigors
• Malaise
• Palpitations
• Shortness of breath
• Mental status changes
• Weakness
Identify objective evidence that indicate the presence of an infection.
- Vital signs
- Lab tests
- Radiological imaging
Differences between prophylactic, empiric and culture-directed (aka definitive) antimicrobial therapy
- Prophylactic: Antibiotics given to prevent an infection
- Empiric: Microbiological result not avail; Antibiotic use is based on clinical presentation of likely site of
infection, likely organism causing infection at that site and likely
susceptibility (from antibiogram) - Antibiotics choice is based on patient specific microbiological (ie
culture and susceptibility) results
Host factors that affect the selection of antimicrobial agent to treat infection.
• Age
• G6PD deficiency
• History of allergy and ADR
• Pregnancy or lactation
• Renal or hepatic impairment
• Status of host immune function
• Severity of illness
• Recent antimicrobial use
• Healthcare-associated risk factors
Organism factors that affect the selection of antimicrobial agent to treat infection.
- Identity of the infecting organism
- Susceptibility/Resistance of the infecting organism
Drug factors that affect the selection of antimicrobial agent to treat infection.
• Active against suspected organism
• Ability to reach the site of infection
• Pharmacokinetics-Pharmacodynamics (PK-PD) characteristics
• Route of administration
• Side effect profiles
• Drug interactions
• Cost
Advantages for using combination antimicrobial therapy
Extend spectrum of activity, Achieve synergistic bactericidal effect & Prevent development of resistance
Possible reasons for an unsatisfactory response to antimicrobial therapy
• Inappropriate diagnosis
• Inappropriate choice of agent
• Subtherapeutic concentration
• Collections or abscess – needs surgery or drainage
• Impaired host defense
• Superinfection
• Toxicity of the drug
Alternative causes of high procalcitonin apart from bacterial infection
ESRF/ traumatic brain injury
Vital signs that indicate presence of an infection
- Fever (more than or equal to 38)
- Hypotension (SBP < 120)
- Tachypnea (RR > 22 bpm)
- HR > 90 bpm
- Mental status esp in elderly
Lab tests that indicate presence of an infection
- Elevated/ depressed total white (normal: 4-10 x 10^9 / L)
• Increased neutrophils (normal range 45-75%) *Look at baseline
• Increased C-reactive protein (CRP) (normal <10 mg/L, infection > 40
mg/L)
• Increased erythrocyte sedimentation rate (ESR) (more utility for bone and joint infection)
• Increased procalcitonin (more specific than CRP)
Radiological imaging that indicate presence of an infection
• Look for tissue changes, collections, abscess, obstructions
• X-ray (chest, bone)
• Ultrasound
• Computerized tomography (CT) scan
• Magnetic resonance imaging (MRI)
Why are follow-up culture are much less reliable than pretreatment cultures?
• may result in false negative results
• subsequent cultures may not reflect the initial causative organisms
