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Showing 7 results for Antibiotic Susceptibility
Mohammadreza Nahaei , Reza Bohloli Khiavi , Mohammad Asgarzadeh, Alka Hasani , Javid Sadeghi, Mohammad Akbari Dibavar ,
Volume 7, Issue 1 (4-2007)
Background and Objectives: Pseudomonas aeruginosa is a nosocomial pathogen that presents high antibiotic resistance.There are phenotyping and genotyping methods for epidemiologic study of Pseudomonas aeruginosa such as antibiotic resistance pattern and plasmid profile analysis. Plasmid analysis provides useful information concerning the source of the strains and number of clones present in the epidemies. Thus, this study was conducted to evaluate antibiotic and plasmid profiles of P. aeruginosa strains isolated from in-patients of the Sina Medical Centre of Tabriz to clarify epidemyological correlation among isolated strains.
Methods: During 13 months, 135 strains of P. aeruginosa were isolated from different infections in hospitalized patients at Sina Medical Center of Tabriz. Antibiotic susceptibility tests were performed using disc agar diffusion test. For plasmid DNA extraction and detection of open circular bands from supercoiled ones, modified alkaline lysis procedure and two dimensional electrophoresis were used, respectively. Enzymatic digestion of plasmids was carried out by EcoRI and HincII restriction enzymes.
Results: Resistance rates of strains against antibacterial agents were recorded as: Aztreonam (77%), colistin (74%), ceftazidime (69%), pipracillin (67%), ofloxacin (62%), tobramycin (56%), carbenicillin (54%), gentamicin (51%), ciprofloxacin (22%), amikacin (15%), polymixin B (13%) and imipenem (2%). Plasmid profiles of our test strains revealed that only 67 strains harbored plasmid(s). Number of isolated plasmids ranged 1-6 in each strain with molecular mass of 0.5kb-21kb. When the isolated plasmids were digested using restriction endonuclease enzymes (EcoRI and HincII), in 32% of them similar digestion profiles were obtained by EcoRI indicating a unique source for them.
Conclusion : Our findings suggest high antibiotic resistance and plasmid presence in P. aeruginosa strains isolated from different infections, and there were remarkable similarities among isolated plasmids. Since our test strains had been isolated from various wards in a short period of time, the results raise the possibility of unique source for some strains or high prevalence of genetic exchange among P. aeruginosa strains.
Hadi Peeridoghaheh, Marziyeh Aligholi, Mohammadhosein Dehghan, Parviz Maleknejad,
Volume 8, Issue 1 (4-2008)
Background & Objective: Brucellosis is one of the most common zoonotic diseases in Iran and is endemic in all parts of the country. Patients recorded in 1988 were 71,051(132. 4 per 100,000). Brucella species are facultative intracellular bacteria, and therefore a limited number of antibiotics are effective against these organisms. The aim of this study was the
evaluation of in vitro sensitivity of various antimicrobial agents against 47 brucella melitensis strains isolated from blood culture.
Methods: The susceptibility of 47 Brucella melitensis isolates derived from clinical samples were tested in vitro. The minimum inhibitory concentrations (MICs) of the tested antimicrobials were measured by the agar dilution method.MIC90 and MIC50 values were defined as the lowest concentration of the antibiotic at which 90 and 50 percent of the isolates
were inhibited, respectively. The NCCLS criteria for slow growing bacteria were considered to interpret the results.
Results: Tetracycline (MIC50: 0.13μg/ml, MIC90: 0.25 μg/ml) and streptomycin (MIC50:0.003 μg/ml, MIC90:0.25 μg/ml) had the lowest MICs in vitro against the B. melitensis strains. Norfloxacin had the highest (8 μg/ml) MIC90 value. More than half
isolates presented reduced susceptibility to rifampin (MIC value: 2μg/ml).
Conclusion: Brucella isolates remain susceptible in vitro to most antibiotics used for treatment of brucellosis. There is no significantly important resistance problem for antibiotics targeted against Brucella species in Iran. However, since rifampin is commonly used for prevalent diseases such as tuberculosis, the regional susceptibility pattern of rifampin should be assessed periodically.
Delsuz Rezaee , Gholamreza Zarrini , Mohammad Ahangarzadeh Rezaee,
Volume 14, Issue 1 (4-2014)
Background & Objectives : Acinetobacter baumannii is an opportunistic Gram-negative pathogen with increasing relevance in a variety of hospital-acquired infections especially among intensive care unit patients. A. baumannii is mostly a cause of septicemia, pneumonia and urinary tract infection following hospitalization of patients. In this study antibiotic susceptibility pattern of A.baumannii isolates and molecular typing among isolates resistant by REP-PCR were determined.
Methods : During study, the A. baumannii, were isolated from hospitals in Tehran. The isolates were identified using standard biochemical tests and antibiotic susceptibility was determined by the disk diffusion method. Extraction of DNA and molecular typing of isolates performed using CTAB method and REP-PCR, respectively.
Results : In this study 75 A. baumannii isolates separated from patients with an average age of 51 ± 18.45 years . The highest resistance rate was against azteronam (97%), ceftazidim (93%), cefepime (93%), piperacillin-tazobactam (93%), ciprofloxacin (93%) and ticarcillin (93%) while the lowest resistance rate was against tigecycline (n= 51, 68%), followed by tobramycin (n=24, 32%), ampicillin-sulbactam (n=21, 28%), amikacin (n=16, 21%), and carbapenems (n=11, 15%). The REP-PCR in resistant of A. baumannii isolates showed that the genotypes of A, B and C are the predominant genotypes in the resistant antibiotics.
Conclusion: This study showed a high percentage of resistance to antimicrobial agents among genotypes A, B, and C of the A. baumannii isolates therefore strategies to control the spread of A. baumannii isolates must be designed and evaluated.
E Raeisi, M Ghiamirad,
Volume 15, Issue 3 (9-2015)
Background & Objectives: Salmonellosis is the most common food-borne disease in the world. The purpose of this study was to determine the prevalence of salmonella serogroups and their antimicrobial susceptibility patterns in chicken meat and viscera in Ardabil, Iran.
Methods: In this cross-sectional study done in spring and summer of 2014,260 samples) 160 chicken meat, 50 gizzard and liver) were collected for isolation and identification of salmonella. The technique used in this study was recommended by Iran standard organization andKirby-bauer method was also used for detection of antibiotic resistance.
Results: Amongallthe samples,the range of detected salmonella was 10%I n which the 42.3% of them detected in spring and 57.7% in the summer.92.3% of samples belong to C serogroup and 3.8% of them were serogroup B and 3.8% serogroup D. All isolates show resistance to at least two antibiotics. Concurrent resistance to 2-6 antibiotics was detected in 70% of the isolates. The highest resistance was to Nalidixicacid�and Streptomycin (100%)and toTetracyclin (92.3%), Penicillin (88.5%), Neomycin, Kanamycin and Furazolidon (84.6%), cloramfenicol (73.1%), Ofloxacin (15.4%), Co-Amoxi clave and Ampicillin (11.5%) and Siprophloxacin 7.7%. The lowest levels of resistance were for Gentamycin and Amikacin (3.8%). No salmonella isolates were resistant to ceftazidime, Azitromicin, Meropenem, Imipenem and cefixime.
Conclusion: According to 10% pollution to salmonella and prevalence of serogroup C and salmonella importance in the human&rsquos health, as well as high rate of antibiotic resistance of isolates, applying a health strategy for reduction of contamination level is necessary.
Leila Arbabi, Mina Boustanshenas , Maryam Adabi, Sara Fathizadeh, Samira Rasouli Koohi , Mastane Afshar, Mohammad Rahbar, Ali Majidpour, Malihe Talebi, Mahshid Talebi-Taher ,
Volume 15, Issue 4 (1-2016)
Background & objectives: Enterococci are among the normal microbial flora in human and animals digestive tract. The nosocomial pathogenicity of enterococci has emerged in recent years and has caused great concern due to developing resistance to many antimicrobial agents. The aim of this study was to investigate and identify the prevalence of VRE (vancomycin resistant enterococcus) within Enterococci isolates obtained from different parts of the hospital.
Methods: Putative Enterococci (n=120) were isolated on Membrane Filter Enterococcus Selective Agar Medium and supplemented with 2, 4 and 8 µgr/ml vancomycin in medical samples. A total isolates passed the standard biochemistry tests for the genus and species as well as their specific primers. The antibiotic susceptibility was determined by the disc diffusion method for 8 antibiotics. Microbiologically-influenced corrosion (MIC) of vancomycin was also done using Agar-dilution assay by CLSI recommendations.
Results: Results showed that 38 and 84 of the isolates were E. faecium and E.faecalis, respectively. According to antimicrobial susceptibility tests 45, 88, 103, 42, 83, 73, 54 and 95 of the isolates were resistant to vancomycin, tetracycline, gentamicin, chloramphenicol, ciprofloxacin, penicillin, ampicillin and erythromycin, respectively. MIC test on 70% of the isolates was>256 µgr/ml.
Conclusion: Despite the fact that the prevalence of VRE strains belongs to two species, E. faecium had high resistance to a broad range of antibiotics. The results of this study indicate the important role of medical samples as reservoirs of resistance elements. Early detection of VRE with their virulence trait will help in preventing the spread of vancomycin resistant enterococcus species and urgent infection control is required in hospital setting
Maryam Tajoadini, Babak Kheyrkhah, Kuomars Amini,
Volume 18, Issue 1 (4-2018)
Background & objectives: Shigella species are one of the most common causes of dysentery and sometimes death, especially in children and those with immunodeficiency. The variety of causative agents (Shigella species) and the development of drug-resistant strains make it difficult to select an appropriate antibiotic for the treatment of shigellosis. One of the most important factors involved in the resistance of Shigella isolates is the presence of extended spectrum beta lactamases (ESBLs) genes. The aim of this study was to determine the frequency of blaPER, blaGES and blaVEB genes in Shigella sonnei isolated from patients with dysentery using multiplex-PCR method and to determine the antibiotic susceptibility patterns of these isolates.
Methods: A total of 60 isolates of Shigella sonnei were collected from different hospitals and medical diagnostic laboratories in Kerman province. Specimens from different age groups were cultivated in special media and confirmed by biochemical tests. The presence of blaPER, blaGES and blaVEB genes were investigated using specific primers and multiplex-PCR method. Antibiotic susceptibility test was performed by disc diffusion method based on CLSI standards.
Results: Multiplex-PCR results showed three samples had blaPER gene, but none of them had blaVEB or blaGES genes. Also, the results of antibiotic susceptibility test showed the highest resistance for amoxicillin- clavulanic acid (53.3%) antibiotic and the highest sensitivity for tetracycline (85%) antibiotic.
Conclusions: The results of the experiments indicated the presence of blaPER gene in Shigella sonnei isolates. In addition, the results showed high resistance of isolates to amoxicillin clavulanic acid and ceftriaxone antibiotics. Therefore, careful medical care and proper and timely use of appropriate antibiotics are essential to prevent the spread of resistant isolates.
Lida Jalali Dizage, Mohammad Reza Nahaei, Javid Sadegi,
Volume 19, Issue 3 (10-2019)
Background & objectives: Urinary tract infection (UTI) is one of the most common types of human infections and Escherichia coli and Klebsiella pneumonia are the main causes of urinary tract infection among the gram negative bacteria. The prevalence of extended-spectrum β-lactamases (ESBLs) among these bacteria and hence resistant strains to β-lactam antibiotics have increased in recent decades. Several types of extended-spectrum β-lactamases, such as TEM, SHV and CTX-M have been identified, which are prominently present in the strains of E. coli and K. pneumoniae. The objective of this study was to determine the prevalence of TEM and SHV genes in E. coli and K. pneumoniae isolates of urinary tract infections by using phenotypic and molecular (PCR) techniques in microbiology laboratory at medical school of Tabriz Islamic Azad University.
Methods: In this cross-sectional descriptive study, 50 isolates of E. coli and 50 isolates of K. pneumoniae collected from urinary tract infections from out-patients in Tabriz. Antibiotic sensitivity patterns of isolates were studied against 14 antibiotics by disk diffusion test (Kirby Bauer) and also confirmatory tests were performed using combined antibiotic tests. Finally TEM and SHV genes were investigated using molecular methods (PCR).
Results: Twenty five isolates (25%) out of 100 bacterial isolates were identified as ESBL-producing isolates of which 13 isolates (26%) were E. coli and 12 isolates (24%) were K. pneumoniae. The TEM and SHV genes were detected in 2% and 4% of E.coli and 0% and 2% of K. pneumoniae isolates, respectively.
Conclusion: The presence of these genes among our isolates confirmed ESBL genes in these medically important bacteria leading to resistance against β-lactam antibiotics which are routinely used in their treatments. The low frequency of the studied genes could be because of the source of our isolates from out-patients which are not generally exposed to antibiotics