Cotherapy of infectious disease

• Correct selection, use, and monitoring of clinical response of antibiotics is important
• Guiding principles for antimicrobial therapy


  • Make the correct diagnosis
  • Do no harm!
• Goals of antimicrobial therapy

  Cure the patient's infection<|>Limit harm by minimizing patient risk for adverse effects, including secondary infections<|>Limit societal risk from antimicrobial-resistant bacteria
• Types of infections


  • Nosocomial
  • Community acquired
• Endogenous infection


  Arise from alteration in one's own normal flora
• Exogenous infection


  Acquired from an external source
• What is the difference between virulence and resistance?
• Clinical presentation and diagnosis

  • Physical examination: Fever
  • Imaging studies: Radiographs, CT, MRI
  • Non-microbiologic laboratory studies: WBC, ESR, CRP
  • Microbiologic studies: Culture
• Fever


  A rise in temperature arising as part of the overall host response to microbial toxins. It is a non-specific sign
• Fever may also be caused by medications, trauma, and other medical conditions
• Some patients with infections may present with hypothermia, elderly patients may be afebrile, and patients with localized infections may also be afebrile
• Considerations for selecting antimicrobial regimens

  • Drug specific: Spectrum of activity, Dosing, Pharmacokinetic properties, Pharmacodynamic properties, Adverse effect potential, Drug-interaction potential, Cost
  • Patient specific: Anatomic location of infection, Antimicrobial history, Drug allergy history, Renal and hepatic function/Age, Concomitant medications, Pregnancy or lactation, Compliance potential
• Outcome evaluation


  • Patient education
  • De-escalation of antimicrobial therapy based on culture results
  • Discontinuation of antibiotics that are providing a spectrum of activity greater than necessary
  • Discontinuation of duplicative spectrum antibiotics
  • Switching to a narrower spectrum antibiotic once a patient is clinically stable
  • Switch from IV to oral
• Monitoring


  • Monitor for clinical response and adverse effects: Efficacy, Toxicity, Imaging, Lab data
• Causes of failure of antimicrobial therapy

  • Inadequate diagnosis resulting in poor initial antimicrobial or other non-antibiotic drug selection
  • Poor source control
  • Development of a new infection with a resistant organism
• Source control


  Reevaluate for sources of untreated infection and perform source control
• Majority of bacterial skin infections are caused by the gram-positive bacteria Staphylococcus and Streptococcus spp.
• Empiric antibiotic therapy for bacterial skin infections

  • Penicillinase-resistant penicillins
  • First-generation cephalosporins
  • Azithromycin
  • Clarithromycin
  • Amoxicillin-clavulanic acid
  • Second-generation fluoroquinolone
• Gram-negative coverage is usually indicated in children under three years and in patients with diabetes or who are immunocompromised
• Boil (furuncle)


  A deep inflammatory nodule developing from a preceding folliculitis (inflammation of the follicles)
• Investigations for boils


  • FBC
  • FBS (if diabetes is suspected)
  • Sensitivity testing for recurring infection
• Treatment objectives for boils

  • To treat infection
  • To relieve pain
  • To identify underlying condition
  • To prevent complication eg: scars & keloids
• Interventions for boils


  • Pharmacological: Flucloxacillin, Erythromycin, Clarithromycin
  • Non-pharmacological: Incision & drainage of pus, Wound dressing
• Buruli ulcer (BU)


  A necrotizing skin infection caused by Mycobacterium ulcerans
• BU is the 3rd most important mycobacterial disease globally in immune competent individuals
• Epidemiology of BU


  • Focal distribution of cases
  • Late reporting of cases
  • Lack of health facilities including laboratory expertise and infrastructure for case confirmation in endemic countries of Africa
• BU is currently reported in 33 countries, with the greatest disease burden in West Africa
• Clinical presentation of BU

  • Variable presentation based on geography
  • Lack of pain
  • Nodule gradually erodes leaving a well-demarcated ulcer with wide undermined edges
• Categories of BU


  • Category 1: single lesion < 5 cm in diameter
  • Category 2: single lesion 5–15 cm in diameter
  • Category 3: single lesion >15 cm in diameter, multiple lesions, critical sites, and osteomyelitis
• Investigations for BU


  • Wound swab for AFBs, C&S
  • Skin biopsy for Histopathology
• Treatment objectives for BU

  • To limit extent of tissue destruction
  • To prevent disability
  • To treat bacterial infection (1o & 2o)
• Treatment for BU


  • Rifampicin PO and IM streptomycin/Clarithromycin PO
  • Surgery as an adjunct for improving wound healing and correction of deformities
• Fungal skin infections are widespread and although not life-threatening can cause morbidity
• Causes of increased prevalence of fungal skin infections

  • Worldwide travel
  • High numbers of immunocompromised patients
  • Growing use of broadspectrum antibiotics
• Aetiology of fungal skin infections

  • Dermatophyte fungi (Trichophyton, Microsporum and Epidermophyton species)
  • Yeasts (Malassezia furfur and Candida)
• Investigations for fungal skin infections

  • Microscopy
  • Culture
  • FBS & HIV status
• Treatment goals for fungal skin infections

  • Eradicate infection
  • Prevent transmission
  • Prevent complications & sequale
  • Identify & treat predisposing or underlying conditions
• General principles of treatment for fungal skin infections

  Topical therapy is first line, with principal side-effects being local irritation and sensitivity reactions. Treatment is generally required for 4-6 weeks.<|>Oral therapy is used for chronic infections, extensive or disabling disease, immunocompromised patients, or patients unresponsive or intolerant to topical treatment.
• Fungal skin infections and their treatments

  • Tinea capitis: Oral griseofulvin, terbinafine
  • Tinea corporis: Topical benzoic acid/clotrimazole/miconazole, oral griseofulvin/itraconazole/terbinafine
  • Tinea pedis: Topical antifungal creams/ointments, oral itraconazole>terbinafine>griseofulvin>fluconazole
  • Candidiasis: Topical nystatin/clotrimazole/miconazole, oral azoles
• Candidiasis


  Infections caused by Candida albicans, particularly in warm and moist areas of the body