Gentamicin-resistance plasmids in an intensive care unit

Area of Science:

• Microbiology
• Infectious Diseases
• Molecular Biology

Background:

• Antibiotic resistance in Enterobacteriaceae is a significant healthcare concern.
• Plasmids are known to play a role in the dissemination of antibiotic resistance.
• Understanding resistance mechanisms in intensive care units is crucial.

Purpose of the Study:

• To investigate the role of plasmids in endemic antibiotic resistance among Enterobacteriaceae.
• To identify the prevalence and characteristics of gentamicin-resistant gram-negative bacilli (GRGNB) in a medical/coronary care unit.
• To determine if plasmid spread contributes to antibiotic resistance dissemination within the unit.

Main Methods:

• Prospective study involving culture surveys of patients, staff, and environment.
• Sampling of new admissions and ongoing monitoring throughout their stay.
• Isolation and characterization of GRGNB, including plasmid analysis via restriction endonuclease digestion and conjugation/transformation experiments.

Main Results:

• 12% of patients (147 total) were colonized with 20 strains of GRGNB.
• 7 of 24 GRGNB strains (29%) were Enterobacteriaceae carrying plasmids with gentamicin-resistance determinants.
• Identical plasmids (93 kb and 60 kb) were found in different bacterial species and environments within the hospital, indicating spread.

Conclusions:

• Specific R-plasmids are implicated in the dissemination of gentamicin resistance in this intensive care unit.
• The spread of plasmids like the 93 kb and 60 kb plasmids likely contributes to endemic antibiotic resistance.
• This highlights the importance of monitoring plasmid dynamics in healthcare settings to control resistance.