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Increasing prevalence of gastrointestinal colonization with ceftazidime-resistant gram-negative bacteria among
Kerri A Thom1, Judith A Johnson, Sandra M Strauss
1Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA. kthoms@medicine.umaryland.edu
Background:
The occurrence of nosocomial infections due to third-generation cephalosporin-resistant gram-negative bacteria is increasing. Gastrointestinal colonization is an important reservoir for antibiotic-resistant bacteria, and it often precedes clinical infection.
Objective:
To estimate the prevalence of gastrointestinal colonization with ceftazidime-resistant gram-negative bacteria among intensive care unit (ICU) patients at a university-affiliated tertiary-care hospital during 2 distinct periods and to assess whether, at any time during the index hospitalization, colonized patients had a clinical culture positive for the same organism that was recovered from surveillance culture.
Setting:
Two ICUs at the University of Maryland Medical Center, a 656-bed tertiary-care hospital located in Baltimore, Maryland. Both ICUs provide care to adult patients.
Methods:
We performed a cross-sectional study of adult patients admitted to the medical ICU or the surgical ICU from June 14 to July 14, 2003, and from June 14 to July 14, 2006. Perirectal swab samples were obtained for surveillance culture on admission to the intensive care unit, weekly thereafter, and at discharge. Each culture sample was plated onto MacConkey agar supplemented with ceftazidime.
Results:
In 2003, a total of 33 (18.8%) of 176 patients were colonized with ceftazidime-resistant gram-negative bacilli; in 2006, 60 (31.4%) of 191 patients were (P<.01). This increase was largely driven by an increase in ceftazidime-resistant Klebsiella isolates (which accounted for 6.4% of isolates in 2003 and for 22.8% in 2006; P<.01). In 2003, a total of 16 (48.5%) of 33 colonized patients had a clinical culture positive for the same organism that was recovered from the perirectal surveillance culture, compared with 22 (36.6%) of 60 colonized patients in 2006 (P=.28).
Conclusion:
Our data suggest that gastrointestinal colonization with ceftazidime-resistant gram-negative bacilli is common, that its prevalence is increasing, and that colonization may result in clinical cultures positive for these bacilli.
Insights
Gastrointestinal colonization with ceftazidime-resistant gram-negative bacteria is increasing in intensive care units (ICUs). This colonization is common and can lead to positive clinical cultures, highlighting a growing public health concern.
Area of Science:
- Infectious Diseases
- Microbiology
- Critical Care Medicine
Background:
- Nosocomial infections caused by third-generation cephalosporin-resistant gram-negative bacteria are a growing concern.
- Gastrointestinal colonization serves as a significant reservoir for antibiotic-resistant bacteria, often preceding clinical infections.
Purpose of the Study:
- To determine the prevalence of gastrointestinal colonization with ceftazidime-resistant gram-negative bacteria in intensive care unit (ICU) patients.
- To assess the link between gastrointestinal colonization and positive clinical cultures for the same organisms during hospitalization.
Main Methods:
- A cross-sectional study was conducted in two ICUs at the University of Maryland Medical Center.
- Surveillance cultures of perirectal swab samples were obtained from adult ICU patients in 2003 and 2006.
- Cultures were plated on MacConkey agar supplemented with ceftazidime to detect resistant gram-negative bacteria.
Main Results:
- The prevalence of colonization increased from 18.8% in 2003 to 31.4% in 2006 (P<.01).
- This rise was primarily due to an increase in ceftazidime-resistant Klebsiella isolates.
- A significant proportion of colonized patients had positive clinical cultures for the same bacteria (48.5% in 2003 vs. 36.6% in 2006).
Conclusions:
- Gastrointestinal colonization with ceftazidime-resistant gram-negative bacilli is prevalent in ICU patients.
- The prevalence of this colonization is increasing over time.
- Gastrointestinal colonization is a potential source for clinically significant infections caused by these resistant bacteria.
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