Bacteria are the most common nosocomial pathogens. A distinction can be made between:

Commensal bacteria found in the healthy individuals normal flora. These have an important protective role in preventing the colonization by pathogenic microorganisms. Certain commensal bacteria may cause infection if the natural host is compromised. For example, coagulase negative staphylococci causes cutaneous intravascular line infection and intestinal Escherichia coli  are the most common causes of urinary tract infection (UTI).

Pathogenic bacteria have greater virulence and cause infections regardless of host status. Anaerobic gram-positive rod like Clostridium causes gangrene. Gram-positive bacteria Staphylococcus aureus  cause a variety of lung, bone, heart and blood infections which are often resistant to antimicrobials. Gram-negative bacteria: Enterobacteriaceae (Escherichia coli, Enterobacter, Proteus, Klebsiella, Serratia marcescens) may colonize sites when the host defences are compromised and cause serious infections (lung, surgical site, and bacteraemia). Gram-negative organisms such as Pseudomonas spp. are frequently found in wet lands and water. They colonize the gastrointestinal tract of hospitalized patients. Some bacteria are a unique risk in hospitals like Legionella species may cause pneumonia through inhalation of aerosols contaminated water (showers, air conditioning and therapeutic aerosols).

  • Coagulase-negative staphylococci
  • Staphylococcus aureus
  • Methicillin resistant Staphylococcus aureus
  • Proteus
  • Escherichia coli
  • Others
  • Klebsiella
  • Serratia marcescens
  • Pseudomonas species
  • Beta-haemolytic streptococci
  • Pseudomonas aeruginosa
  • Legionella species
  • Stenotrophomonas maltophilia
  • Mycobacterium tuberculosis
  • Acinetobacter baumannii
  • Clostridium difficile
  • Vancomycin-resistant Enterococcus

Related Conference of Bacteria

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