Nosocomial consequences of antibiotic usage.

Area of Science:

• Medical Microbiology
• Infectious Diseases
• Hospital Epidemiology

Background:

• Gentamicin was the primary antibiotic in 1979, with Pseudomonas aeruginosa resistance reaching 55% within seven years.
• Amikacin introduction in 1983 led to a rapid increase in resistance, reaching 23% within three years.
• By 1985, resistance to aminoglycosides and third-generation cephalosporins exceeded 50%.

Purpose of the Study:

• To analyze the trends of antibiotic resistance in Pseudomonas aeruginosa at Laiko General Hospital.
• To identify sources and characteristics of multidrug-resistant strains.
• To evaluate the impact of antibiotic consumption on resistance patterns.

Main Methods:

• Retrospective analysis of antibiotic resistance data from 1979 to 1985.
• Correlation of resistance patterns with antibiotic consumption data.
• Identification of resistance mechanisms (AAC(6')I) and serotypes (O:12) in resistant strains.

Main Results:

• Urine samples were the primary source of multidrug-resistant strains; amikacin-resistant strains were implicated in 50% of bacteremias.
• The Intensive Care Unit (ICU) was the most common isolation source, with resistant strains spreading hospital-wide.
• Multidrug-resistant strains were associated with an 11% mortality rate; AAC(6')I was detected in 60% of amikacin-resistant strains.

Conclusions:

• Rising antibiotic resistance, especially to amikacin, poses a significant threat at Laiko General Hospital.
• High antibiotic consumption, with amikacin and newer cephalosporins as first-line agents, correlates with resistance.
• Urgent revisions to antibiotic policies are essential to mitigate the spread of multidrug-resistant Pseudomonas aeruginosa.