Extended spectrum beta lactamase producing Escherichia coli and Klebsiella pneumoniae: risk factors for infection and impact of resistance on outcomes.

BACKGROUND: Extended spectrum beta Lactamases (ESBL) producing Escherichia coli (EC) and Klebsiella pneumoniae (KP) has increased in recent years leading to limitations of treatment options. The present study was undertaken to determine the prevalence of ESBL production among nosocomial isolates of EC and KP and their impact on clinical outcome

METHODS: One hundred and one isolates of EC and KP obtained from patients hospitalized for > 48 hours were included in the study. They were tested for ESBL production by double disc synergy test (DDST) and E test. Co-resistance to fluoroquinolones, aminoglycosides, trimethoprim - sulphamethoxazole, aztreonam and beta lactamase inhibitor combinations and susceptibility to carbapenems were determined by disc diffusion method. Production of AmpC was screened using Cefoxitin discs. They were designated as colonizers or pathogens using clinical data and laboratory parameters. Risk factors assessed were variables related to hospital stay and antibiotics used. The outcome was followed up.

RESULTS: Of 101 isolates, 68 (49 EC, 19 KP) were ESBL producers, 14 being colonizers and 54 pathogens. They were obtained from Blood (4), Respiratory secretions (4), exudates (12) and Urine (48). A high degree of co-resistance was observed to other antibiotics. Susceptibility to carbapenem was universal. Two isolates were AmpC producers. Increased duration of hospital stay of >7 days was a significant risk factor (P < 0.0005). Prior exposure to antibiotics was also an important contributing factor.

CONCLUSION: The high prevalence of ESBL in EC and KP is associated with a multitude of infections in hospitalized patients with a significantly longer duration of hospital stay, increased morbidity and greater hospital charges. This necessitates emphasis on interventional strategies to control and prevent their spread in health care centers.