QJM Advance Access originally published online on September 6, 2006
QJM 2006 99(10):718-719; doi:10.1093/qjmed/hcl100
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Correspondence |
Evaluating broad-spectrum antimicrobials
Sir,In a recent QJM paper, investigators at the Shaare Zedek Medical Center, Jerusalem studying the prospective utility of cefepime, piperacillin-tazobactam and meropenem recommended formal infectious disease consultation for their appropriate usage.1 Ideally, empirical treatment regimens with broad-spectrum and/or costly antimicrobials would be based on unit-specific data. Nevertheless, any retrospective data on the in-vitro susceptibility profile of bacteria encountered in local intensive care could help guide selection of an appropriate approach. Therapeutic intervention is immediate and cannot be linked with the in-vitro susceptibility profile of the isolates. Background information on the local prevalence of extended spectrum ß-lactamase producers (ESBL) and methicillin-resistant S. aureus (MRSA) would thus be an asset.
In the Sant Parmanand Hospital, a 140-bed, tertiary-care, private-sector hospital in Delhi, antimicrobial susceptibility of isolates encountered from clinical material is primarily computed for 28 antimicrobials. Retrospective data from October 2004 onwards are used to recommend antibiotics with susceptibility exceeding 75% against organisms encountered in urinary tract, blood and pyogenic foci.2 Initial screens would exclude cefepime, piperacillin-tazobactam and meropenem. However, from December 2005, a two-tier susceptibility protocol has been used on isolates from patients in the medical and surgical intensive care units, nursery, or patients with aggressive infections. They are tested for in-vitro susceptibility for cefepime, piperacillin-tazobactam and meropenem. Among 114 isolates up until May 2005, there were 46 Klebsiella strains, 30 E. coli, 10 Proteus, 8 Pseudomonas, and 20 S. aureus. The respective cumulative susceptibilities to cefepime, piperacillin-tazobactam and meropenem, were 52.8%, 77.2% and 82.3%. Among Gram-negative isolates and S. aureus, there was no statistical difference for the susceptibility values among cefepime, and meropenem. However, piperacillin-tazobactam was more effective against S. aureus isolates (Fisher's p = 0.04). For Klebsiella, susceptibility was highest with meropenem, followed by piperacillin-tazobactam and cefepime.
From March 2006, phenotypic separation for extended spectrum ß-lactamase (ESBL) producers was started. Among 29 isolates to date, including 17 Klebsiella, 10 E. coli, and one each Proteus and Pseudomonas, there were 18 ESBL producers. They included 10 Klebsiella strains, 9 E. coli, and one Pseudomonas. They were isolated from urine (10 cases), lungs (6 cases), blood (4 cases) and purulent material (1 case). There were MRSA episodes in intensive care units during September 2004 and May 2005. A dialogue between clinical microbiology and clinicians ensured an effective switch over from a ß-lactam to a non-ß-lactam antimicrobial.
Continuous in-vitro surveillance for susceptibility to the broadest-spectrum antibiotics3 should be associated with both formal and informal infectious disease consultation.1 For health-care centres with financial constraints, a two-tier susceptibility profile,2 along with prior information about the prevalence of ESBL and MRSA, would assist in the appropriate usage of these drugs.
Sant Parmanand Hospital
18 Alipore Road
Delhi 110054
India
email: subhashji{at}hotmail.com
References
1. Raveh D, Muallem-Zilcha E, Greenberg A, Wiener-Well Y, Schlesinger Y, Yinnon AM. Prospective drug utilization evaluation of three broad-spectrum antimicrobials: cefepime, piperacillin-tazobactam and meropenem. Q J Med 2006; 99:397–406.
2. Arya SC, Agarwal N, Agarwal S. Straightforward representation of antimicrobial chemotherapeutics susceptibility profiles in a private tertiary care hospital. J Infect 2005; 51:333–5.[CrossRef][Web of Science][Medline]
3. Rhomberg PR, Fritsche TR, Sader HS, Jones RN. Antimicrobial susceptibility pattern comparisons among intensive care unit and general ward Gram-negative isolates from the Meropenem Yearly Susceptibility Test Information Collection Program (USA). Diagn Microbiol Infect Dis 2006; 54:249–57.[CrossRef][Web of Science][Medline]
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