Overview of nosocomial infections caused by gram-negative bacilli

Area of Science:

• Infectious Diseases
• Epidemiology
• Critical Care Medicine

Background:

• Hospital-acquired infections (HAIs) pose a significant threat in intensive care units (ICUs).
• Gram-negative bacilli are frequently implicated in HAIs, including pneumonia, surgical site infections (SSIs), urinary tract infections (UTIs), and bloodstream infections (BSIs).
• Understanding the evolving epidemiology of these pathogens is crucial for effective infection control.

Purpose of the Study:

• To analyze the epidemiological trends of gram-negative bacilli in ICUs over a 18-year period (1986-2003).
• To determine the association of gram-negative bacilli with major HAIs: pneumonia, SSI, UTI, and BSI.
• To identify changes in the prevalence of specific gram-negative pathogens, such as Acinetobacter species, and antimicrobial resistance patterns.

Main Methods:

• Analysis of a large dataset (>410,000 bacterial isolates) from the National Nosocomial Infections Surveillance (NNIS) System.
• Retrospective review of HAIs in ICUs from 1986 to 2003.
• Statistical analysis to assess trends and significance, including the Cochran-Armitage chi2 test for trend.

Main Results:

• Gram-negative bacilli were consistently associated with a high proportion of HAIs in ICUs.
• The percentage of BSIs and SSIs linked to gram-negative bacilli decreased significantly from 1986 to 2003.
• Pneumonia and UTI episodes associated with gram-negative bacilli remained stable, but Acinetobacter species increased in ICU pneumonia cases.
• Uniform increases in antimicrobial resistance rates were observed for specific pathogen-antimicrobial combinations.

Conclusions:

• Gram-negative bacilli remain a major concern for HAIs in ICUs.
• While some infection types show decreasing trends, the rise of specific pathogens like Acinetobacter in pneumonia warrants attention.
• Antimicrobial resistance trends highlight the need for ongoing surveillance and updated treatment guidelines.