Journal of Research in Pharmacy Practice

Abstract Objective: Gram‑negative bacilli are the most important cause of nosocomial urinary 
tract infections (UTIs). The production of extended‑spectrum β‑lactamase (ESBL) enzymes 
is a common mechanism of resistance among these bacteria. The aim of this study was to 
determine the rate of ESBL producing Gram‑negative bacteria causing nosocomial UTI in a 
referral hospital as well as their susceptibility pattern to the most commonly used antibiotics.
Methods: In a prospective cross‑sectional study performed over a 6‑month period, urinary 
specimens obtained from hospitalized patients with documented culture‑proved nosocomial 
UTI (age range of 1-87 years). Isolated aerobic Gram‑negative bacteria underwent further 
microbiologic tests for detection of ESBL, as well as antimicrobial susceptibility test using 
Kirby-Bauer (disk diffusion) and E‑test methods.
Findings: During the study period, 213 urine samples were detected to have growth of 
Gram‑negative organism. Escherichia coli was the most frequently isolated organism (61%). 
ESBL was detected in 102 isolates including 38.5% of E. coli, 39.5% of Klebsiella pneumonia, 
88.5% of Pseudomonas aeruginosa, and 100% of Acinetobacter baumannii strains. Imipenem 
and meropenem were the most effective antibiotics on E. coli and K. pneumoniae strains. P.
aeruginosa and A. baumannii strains showed high resistance to all tested antibiotics.
Conclusion: Large numbers of Gram‑negative bacteria causing nosocomial UTIs produce 
ESBL with most being multidrug‑resistant. Therefore, routine ESBL detection testing and 
subsequent antibiogram with disk diffusion method could be useful to determine the best 
treatment options for UTI.

Abstract Objective: Synergistic effect between commonly used antibiotics against nosocomial 
multidrug-resistant strains of Staphylococcus aureus, if present, could provide a viable 
option as an alternative therapy for infections due to this pathogen. The aim of this study 
was searching for any synergistic effect between several antibiotics against drug-resistant 
strains of S. aureus with nosocomial origin using double-disk synergy test and to determine 
the applicability of this test for such a purpose.
Methods: Over a 6-month period, strains of S. aureus isolated from clinical specimens 
of hospitalized patients with documented nosocomial infection underwent disk diffusion 
test using antibiotic disks of oxacillin, cephalothin, clindamycin, ciprofloxacin, vancomycin, 
cotrimoxazole, rifampin, erythromycin, gentamicin and meropenem. Double-disk synergy test 
was performed for all isolates resistant to at least two of applied antibiotics. Combinations 
of all possible pairs of antibiotics (to which the microorganism was resistant) were tested 
by placing antibiotic disks at distance of 20 mm from each other (center to center). After 
16-20 hours of incubation, if synergistic effect was present among two antibiotics, an inhibition 
zone was formed between their disks.
Findings: Among all of possible two-antibiotic combinations tested for 41 resistant isolates, 
only two cases of synergistic effect were detected; both effects were among rifampin and 
cotrimoxazole.
Conclusion: The combination of rifampin and cotrimoxazole could provide a viable option 
for treatment of infections due to resistant strains of S. aureus; however, clinical trials are 
needed before any new recommendation. Also, double-disk synergy test seems to be capable 
of detecting the synergistic effect between antibiotics at in vitro level.

Abstract Objective: About 73% of death cases in the first 5 days after burning are due to infection 
complications. The aim of this study was to identify the causing agents of infections in burn 
patients and the sensitivity pattern of them to the commonly used antimicrobials in an 
Iranian Burn center University Hospital.
Methods: In this cross-sectional study, patients who were admitted to one of the Iranian 
Burn center University hospitals in 2009 and had nosocomial infection due to burn wound, 
whom received antimicrobial agents for therapeutic reasons, with a hospitalization period of 
more than 48 hours were enrolled. Gram stain analyses were performed to help identifying 
growing colonies. Differential tests for identification of pathogenic bacteria species were 
performed following primary tests. E-test strips of each antimicrobial were placed on the 
culture medium plate in order to determine the minimum inhibitory concentration Studied 
antimicrobials for isolated Gram-negative bacteria were meropenem, piperacillin/tazobactam, 
ceftriaxone, cotrimoxazole, and for Staphylococcus aureus, vancomycin, piperacillin/
tazobactam, cotrimoxazole, and cephalothin.
Findings: Only 16% of Pseudomonas aeruginosa species were sensitive to meropenem, and 
13% were sensitive to piperacillin/tazobactam. Ten out of 29 Klebsiella species (34%) were 
sensitive to meropenem and piperacillin/tazobactam. All isolated strains of Staphylococcus 
aureus were sensitive to vancomycine while they were all resistant to cotrimoxazole.
Conclusion: Pseudomona, Klebsiella and Staphylococcoci are the most common species 
causing burn infection in this medical center. Results showed the importance of limiting 
irrational use of wide-spectrum antimicrobials and recommends strict management of 
infections in burn injury centers.