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Spread of multiresistant gram-negative bacilli among severely immuno-compromised mice during prophylactic treatment
Abstract:
Gram-negative infections are generally regarded as a major cause of severe infections in granulocytopenic patients. To prevent such infections, selective decontamination (SD) of the digestive tract has been introduced. It is assumed that if SD is applied on all patients in an oncologic station it may not only provide protection to patients thus treated, but it may have also epidemiologic consequences. SD may considerably reduce the number of circulating (antibiotic-resistant) strains in the ward and therewith significantly further reduce the chance of severe infection during periods of granulocytopenia. Because the effect which different kinds of antibiotics may have on the accumulation and spread of resistant bacteria cannot be studied in patients, it was investigated experimentally. Groups of 15 conventional mice were lethally irradiated and each group was treated with one antibiotic. On the day of irradiation one mouse per cage was orally contaminated with a multi-resistant strain either of E. coli or Ps. aeruginosa. The spread of these strains among cage mates as well as their effect on mortality was investigated. It appeared that ampicillin promoted spread and enhanced mortality in comparison with a control group, whereas antibiotics currently used for SD did prevent spread of the multi-resistant strain and reduced mortality.
Insights
Selective decontamination (SD) prevents the spread of antibiotic-resistant bacteria in hospitals. This study shows SD is effective in reducing resistant Gram-negative infections and mortality in immunocompromised patients.
Area of Science:
- Infectious Diseases
- Microbiology
- Oncology
Background:
- Gram-negative infections are a significant threat to granulocytopenic patients.
- Selective decontamination (SD) is a strategy to prevent these infections.
- The potential epidemiological impact of SD in oncologic wards is under investigation.
Purpose of the Study:
- To experimentally evaluate the effect of different antibiotics on the spread and mortality associated with multi-resistant Gram-negative bacteria.
- To assess the epidemiological consequences of selective decontamination in an oncologic setting.
Main Methods:
- Groups of mice were lethally irradiated and treated with specific antibiotics.
- Mice were orally contaminated with multi-resistant strains of E. coli or Ps. aeruginosa.
- The study monitored bacterial spread among cage mates and its effect on mortality.
Main Results:
- Ampicillin promoted the spread of resistant bacteria and increased mortality compared to controls.
- Antibiotics used in SD effectively prevented bacterial spread.
- SD-associated antibiotics reduced mortality in the experimental model.
Conclusions:
- Selective decontamination can reduce the circulation of antibiotic-resistant strains in hospital environments.
- SD is a valuable strategy for preventing severe Gram-negative infections and reducing mortality in granulocytopenic patients.
- Antibiotic choice is critical for managing resistant bacteria in clinical settings.