ABSTRACT

       Background and Objectives: Pseudomonas aeruginosa is the most frequent opportunistic pathogen isolated from the sputum of patients with cystic fibrosis (CF). Resistance to β -lactam antibiotics may arise from over expression of the naturally occurring AmpC cephalosporinases or acquired extended-spectrum β-lactamases (ESBL). The aim of this study was to determine the antibiotic resistance profiles as well as the prevalence of ESBL and AmpC production in clinical isolates of P. aeruginosa from CF patients in Tehran.

         Methods: Antibiotic resistance of 50 non-duplicate P. aeruginosa isolates was determined by the disc diffusion method. AmpC β-lactamase production was detected by the antagonism disc test and ESBL production was detected by the phenotypic confirmatory test. The presence of ESBL and AmpC genes was assessed by PCR, followed by sequencing the PCR products.

         Results: The antibiotic resistance rates were as follows: 22% to ceftriaxone, 20% to cefotaxime, 10% to imipenem, 8% to carbenicillin and 6% to ticarcillin, 4% each to cefepime, tobramycin, amikacin and aztreonam and 2% to each piperacilin, meropenem and ceftazidime. AmpC production was observed in 47 isolates (94%) and ESBL production was observed in one isolate (2%). PCR results showed that all isolates carried the bla_AmpC β-lactamase gene. One multidrug-resistant isolate carried both bla_TEM and bla_PER-1 genes.

        Conclusion: The results showed that despite the low rate of antibiotic resistance in P. aeruginosa CF isolates,the  presence of multiple β-lactamases even in one isolate is alarming and can complicate the already difficult treatment of chronic infections in the lungs of CF patients.

ABSTRACT

        Background and Objective: Lavandula stoechas is a species of native and permanent plants in Golestan province that belongs to the family Lamiaceae. L. stoechas has been used in traditional medicine for treatment of various diseases. The aim of this study was to extract essential oil using steam distillation method from the flowers of L. stoechas collected from Jahan-nama region in the Golestan province, and evaluate its antibacterial activity.

        Methods: Steam distillation (Clevenger) and GC-MS system were used to separate volatile oils and identify the essential oil components, respectively. Two methods of disk diffusion and broth micro dilution were used to evaluate the antimicrobial effect of L. stoechas essential oil. Six bacterial species including Staphylococcus aureus, Bacillus sp., Enterococcus faecalis, Salmonella enteritidis, Escherichia coli and Pseudomonas aeruginosa were tested.

       Results: The essential oil yield was 0.28%. The main components were camphor (71.86%), 1, 8-cineole (4.08%), linalool (3.77%) and borneol (3.19%). The essential oil showed no inhibitory effect on P. aeruginosa and E. faecalis, while it had different inhibitory effects on other bacteria. S. aureus and Bacillus sp. showed the highest sensitivity with inhibition zone diameter of 32 and 29 mm, respectively.

        Conclusion: The results of this study showed that the essential oil of L. stoechas has high inhibitory and antimicrobial activity particularly against Gram-positive bacteria, which may be due to the presence of 71.86% camphor in its composition.