Pharmacotherapy of Infectious Diseases

PHARMACOTHERAPY OF INFECTIOUS DISEASES

• Course outline: Antimicrobial selection, skin infections, STIs
• Assessment:
  • Assignments: 10%
  • Interim assessments: 30%
  • Examination: 60%
  • Group presentations: 15 groups of 4-5 people each, 15 minutes per group

ANTMIORBIAL REGIMEN SELECTION

• Guiding principles:
  • Correct diagnosis
  • Do no harm!
• Goals of antimicrobial therapy:
  • Cure the patient's infection
  • Limit harm by minimizing patient risk for adverse effects
  • Limit societal risk from antimicrobial-resistant bacteria

ETIOLOGY OF INFECTIONS

• Nosocomial infections
• Community-acquired infections
• Endogenous infections: arise from alteration in one's own normal flora
• Exogenous infections: acquired from an external source

PATHOPHYSIOLOGY

• Normal flora: alteration in one's own normal flora can lead to infection
• Disruption of host defenses (e.g., immunocompromise)

CLINICAL PRESENTATION AND DIAGNOSIS

• Physical examination: fever
• Imaging studies: to determine anatomic localization of infection
• Non-microbiologic laboratory studies: WBC, ESR, CRP
• Microbiologic studies: culture, bacterial cultures should be obtained prior to initiating antimicrobial therapy
• Fever:
  • A rise in temperature arising as part of the overall host response to microbial toxins
  • Non-specific sign
  • May also be caused by medications, trauma, or other medical conditions
  • Some patients with infections may present with hypothermia or be afebrile

TREATMENT

• Considerations for selecting antimicrobial regimens:
  • Drug-specific factors (spectrum of activity, dosing, pharmacokinetic and pharmacodynamic properties, adverse effect potential, drug-interaction potential)
  • Patient-specific factors (anatomic location of infection, antimicrobial history, drug allergy history, renal and hepatic function, age, pregnancy or lactation, compliance potential)
• De-escalation of antimicrobial therapy based on culture results
• Discontinuation of antibiotics that are providing a spectrum of activity greater than necessary to treat the infection
• Switching to a narrower spectrum antibiotic once a patient is clinically stable

OUTCOME EVALUATION

• Patient education
• Monitoring:
  • Clinical response and adverse effects
  • Efficacy: vital signs, clinical findings, physical exam findings
  • Toxicity: adverse effects
  • Imaging: repeat diagnostic testing as needed
  • Lab data: WBC, follow-up on C/S tests

FAILURE OF ANTIMICROBIAL THERAPY

• Causes:
  • Inadequate diagnosis resulting in poor initial therapy
  • Inadequate antimicrobial regimen
  • Inadequate duration of therapy
  • Development of resistance
  • Presence of untreated infections
• Consider alternative non-infectious diagnosis

CANDIDIASIS

• Candida albicans: cause infections particularly in warm and moist areas of the body
• Factors associated with increased colonization rates of C. albicans:
  • Broad-spectrum antibiotics
  • Diabetes mellitus
  • Systemic corticosteroid treatment
  • Hematological malignancies and solid tumors
  • Severe traumas and burns
  • Premature birth
• Epidemiology:
  • 3 out of 4 women have at least one bout of vulvovaginal candidiasis in their lifetime
  • More than 90% of HIV-positive patients experience oropharyngeal candidiasis
  • Candidal colonization is at the highest levels during the extremes of ages, in neonates and people older than 65 years

STIs

• Infections that are transmitted from person to person through sexual contact
• Causative organisms are transmitted through blood, semen, vaginal or other body fluids
• Common STIs: gonorrhoea, chlamydia, syphilis, herpes simplex, HIV/AIDS
• Effects on baby:
  • Low birth weight
  • Neurologic problems
  • Eye infection, blindness
• Non-sexual transfer can occur through:
  • Vertical transmission from mother to child during pregnancy, childbirth, or after birth
  • Blood transfusions
  • Organ transplants
  • Shared needles or syringes

HIV/AIDS

• Human Immunodeficiency virus (HIV)
• A retrovirus with a strong affinity for CD4 receptor protein found predominantly on cells of the immune system
• Over time, chronic infection depletes these cells, leaving the body susceptible to infections and tumors
• Progressive deterioration in cellular immune response leads to symptomatic disease and Acquired Immune Deficiency Syndrome (AIDS)
• Transmission of HIV:
  • Sexual contact
  • Vertical transmission from mother to child during pregnancy, childbirth, or after birth
  • Blood transfusions
  • Organ transplants
  • Shared needles or syringes
• Global AIDS statistics:
  • Prevalence is 0.7% among adults
  • 39 million people living with AIDS (1.5 million are children)
  • 2/3 of PLWHA live in Africa
  • 630,000 people died of HIV-related illnesses
  • 85% are aware of their status
  • 75% are accessing treatment
  • 92% have viral suppression
• Ghana AIDS statistics:
  • Adult prevalence is 1.6%
  • >354,000 people living with AIDS
  • 67% are women
  • 8% are children

This quiz covers antimicrobial selection, skin infections, STIs, and discussion points for diseases, including aetiology, epidemiology, and interventions.