Antimicrobials superinfections

Superinfection As with other antimicrobial agents, superinfections caused by resistant organisms (eg. Pseudomonas or Candida species) can occur. 

Certain clinical situations (Figure 28.8) require the use of antibiotics for the prevention rather than the treatment of infections. Since the indiscriminate use of antimicrobial agents can result in bacterial resistance and superinfection, prophylactic use is restricted to clinical situations in which benefits outweigh the potential risks. The duration of prophylaxis is dictated by the duration of the risk of infection. 

Several pathogens are involved including Chlamydia trachomatis, Neisseria gonorrhoeae and Mycoplasma hominis and there may be superinfection with bowel and other urogenital tract bacteria. A combination of antimicrobials is usually required, e.g. metronidazole plus doxycycline by mouth. 

Serra P Santini C, Venditti M, Mandelli F, Martino P (1985) Superinfections during antimicrobial treatment with beta-lactam-aminoglycoside combinations in neutropenic patients with hematologic malignancies. Infection 13(Suppl 1) S115 122... 

Figure 6 Patients already receiving antimicrobial therapy. (A) When pneumonia develops as a superinfection in a patient who has been receiving antimicrobial agents for several days before the appearance of new infiltrates and fiberoptic bronchoscopy is performed immediately without any modifications of the treatment, bacteria responsible for the new infection are then mostly resistant to the antibiotics given previously and culture results will not be modified. (B) In contrast, when fiberoptic bronchoscopy is done after the introduction of new antimicrobial agents, bacteria responsible for the infection are then frequently sensitive to the new antibiotics given and culture results are negative in a high number of cases.

Louria DB, Kaminski T. The effects of four antimicrobial drug regimens on sputum superinfection in hospitalized patients. Am Rev Respir Dis 1962 85 649-665. 

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