Principal of management of infection


The management of infection depends on non-specific and specific therapeutic measures (see the information box) and also on techniques of prevention of infection.

Non-specific management
  • This includes the treatment of general symptoms such as fever, myalgia, headache and thirst, and complications such as dehydration, hypovolaemia, organ failure, haemorrhage and hyperpyrexia
Specific management
  • This involves the use of antimicrobial agents to kill or inhibit the growth of microorganisms

The ability of one microorganism to interfere with the growth of another is called antibiosis and is due to specific diffusible metabolic products termed antibiotics. Since the introduction of penicillin in 1940, research has produced a wide range of antibiotics. In addition, a variety of other chemotherapeutic agents such as metronidazole, trimethoprim, ciprofloxacin and isoniazid followed the demonstration of the therapeutic effects of sulphanilamide in 1935. A general term for all of these substances is antimicrobial agents. Those that kill microorganisms are referred to as bactericidal while agents that inhibit their growth are called bacteriostatic. Table 2.4 illustrates the sites and modes of action on bacteria of selected antimicrobial agents.

Effective therapy is available against all known bacteria, rickettsiae, mycoplasmas and chlamydiae. However, the evolution of antimicrobial resistance is seriously restricting treatment, and reports of total antibiotic resistance in Staph. aureus and enterococci are causing great concern. Specific antiprotozoal compounds are used in the treatment of diseases such as sleeping sickness, leishmaniasis, malaria and amoebic

Mechanisms of action of antimicrobial agents
Site of action in bacteria Mode of action Antibiotic
Nucleic acid synthesis
  • Interrupts folate synthesis
  • Inhibits DNA supercoiling
  • Breaks DNA strands
  • Inhibits RNA polymerase
  • Sulphonamides/trimethoprim
  • 4-quinolones
  • Nitrofurantoin
  • Rifampicin
Protin synthesis
  • Binds to 30S ribosome and causes RNA code misreading
  • Binds to 50S ribosome subunit and blocks translocation
  • Inhibits transfer of amino acids to ribosome
  • Binds to 50S ribosome and blocks RNA attachment
  • Aminoglycosides
  • Macrolides
  • Chloramphenicol
  • Tetracycline
Cell membrane function
  • Disrupts cell membrane
  • Inhibits sterol synthesis
  • Polymyxins
  • Amphotericin
Cell wall synthesis
  • Inhibits carriage of subunits from cell membrane to cell wall
  • Inhibits final cross-linkage of peptidoglycan
  • Vancomycin
  • Cephalosporins/penicillins

dysentery. An increasing number of drugs are available for the treatment of fungal infection. Antimicrobial agents active against viruses are now receiving great attention and use of antiherpes drugs is common and highly effective. Similarly, antiretroviral drugs have revolutionised the management of HIV.

Concepts of infection
Major manifestations of infection
Principles of management of infection
Diseases due to viruses
DNA viruses
Diseases due to chlamydiae
Diseases due to rickettsiae
Diseases due to bacteria
  • Streptococcal infections
  • Staphylococcal infections
  • Corynebacterial infections
  • Bacillus infections
  • Bordetella infections
  • Salmonella infections
  • Food poisoning
  • Dysentery
  • Other true bacterial infections
  • Mycobacterial infections
Diseases due to spirochaetes
  • Leptospira infections
  • Borrelia infections
  • Treponema infections
Diseases due to fungi (mycoses)
  • Cutaneous fungal infections
  • Subcutaneous fungal infections
  • Systemic fungal infections
Diseases due to protozoa
Diseases due to helminths
  • Trematode (fluke) infections
  • Cestode (tapeworm) infections
  • Nematode (roundworm) infections
  • Zoonotic helminth infections
Diseases due to arthropods
Sexually transmitted diseases
  • Sexually transmitted bacterial diseases
  • Sexually transmitted viral diseases
  • Miscellaneous conditions