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Showing 9 results for Antibiotic Resistance Pattern

Tajaddin Akbarzadeh Khiavi , Mohammadreza Nahaei , Ahmad Rahmati , Mohammad Asgharzadeh, Javid Sadegi ,
Volume 7, Issue 1 (4-2007)

  Background and Aims: Staphylococcus aureus as aGram- positive coccus causes a variety of infections in humans. It is one of the infectious agents in hemodialysis patients. Those patients who carry this organism at their nose are exposed to infection and possible morbidity and mortality due to this bacterium. Resistance to antibiotics in staphylococci is increasing. Resistance development is due to mutation and by plasmid DNA transmission. The aim of this study was to determine plasmid profile and antibiotic resistance of Staphylococcus aureus strains isolated from nasal carriers in dialysis patients in Imam Khomeini Medical Center. Susceptibility testing to antibiotics, plasmid extraction and analysis and epidemiologic relationship of these isolates were investigated.

  Methods: In this study nasal specimens of 107 patients in dialysis ward of Imam Khomeini Medical Center were collected and cultured on blood agar plates. The colonies were identified as S.aureus strains. The susceptibility of 50 strains isolated from the patients against 12 antibiotics were tested using Kirby- Bauer standard method. A standard S.aureus strain (ATCC29213) was used to control quality of antibiotic discs. The isolates were cultured on LB medium and plasmid DNAs were extracted and electrophoresed on agarose gel using Parisi et al method.

  Results : The results of resistance rate against 12 used antibiotics were as follows: resistance of the strains against gentamicin, oxacillin, neomycin, clindamycin, erythromycin, cotrimoxazole, choloramphenicole, tetracycline, and ciprofloxacin were 20%, 28%, 30%, 26%, 30%, 44%, 32%, 36%, and 10%, respectively. All of the strains were resistant to amoxycillin and penicillin and none of them were resistant to vancomycin. Of 50 S. aureus strains, only 27 strains contained plasmid DNA. Most of the strains revealed a big plasmid. Plasmid profiles of the strains will be presented.

  Discussion: Our results showed that there was a close relationship between high resistance to antibiotics and presence of plasmids in S. aureus strains. Similarities among resistance to antibiotics and plasmid profiles in our strains isolated from the same ward showed that these strains were from the same sources and indicated a unique clonal possibility. The resistance to antibiotics of the strains lacking plasmids could be from choromosomal resistance

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.

Mojtaba Nikbakht , Siyamak Hassan Nagad , Babak Rezazade, Abbas Nagizadeh Baghi , Faiiaz Gorbani , Fatemeh Faraji, Nasim Karimvand ,
Volume 9, Issue 1 (4-2009)

  Background and Objective: Staphylococcus aureus is known as an important pathogen causing a variety of bacterial infections. Treatment of this bacterium with antibiotics has led to antibiotic-resistancey, especially against methicillin (MRSA) and more recently rare resistance against vancomycin. The aims of this study were to determine nasal carriage rates of S. aureus in Meshgin Shahar Valiasr hospital’s personnel and to determine antibiotic-resistance patterns in the mentioned isolates.

  Methods: Staphylococcus aureus isolates were collected from the nose of 200 hospital personnel in Meshgin Shahar Valiasr hospital in a 2 month period in 2006. Antibiotic sensitivity of the collected strains were tested against antibiotics used in routine treatment of S. aureus infections. Oxacillin agar was also used to screen for MRSA according to NCCLS recommendation.

  Results: Our results showed there were 45% and 16% nasal carrier rate for S. aureus and MRSA (methicillin resistant staphylococcus aureus) strains, respectively in hospital personnel. Thirty two isolates were able to grow in oxacillin agar media, indicating 35% MRSA strains. Antibiotic resistant pattern of strains in disks method were recorded as follows: 35% to oxacillin, 97.8% to penicillin, 34% to erythromycin, 2.1% to chloramphenicol, 39.36% to tetracycline, 11.7% to gentamicin, 30.85% to trimetohoprim sulfamethoxazol and 19% to clindamycin. All of the isolates were sensitive to vancomycin and ciprofloxacin.

Conclusion: In this study, nasal carriage rate of Staphylococcus aureus among hospital Personnel was more than community expected rate (%40) and lower than hospital expeeted rate (%50-80). All of the test strains were sensitive to Vancomycin.
Abbasali Imani Foolad, Maryam Hosainzadeh, Seiyed Fazlollah Mousavi ,
Volume 11, Issue 1 (4-2011)

  Background & Objectives: Pseudomonas aeruginosa is a Gram-negative and aerobic bacterium. Exotoxin A is one of the important toxins produced by the bacterium and it is the main cause of mortality. About 90% of P. aeruginosa strains produce this toxin. Biofilm is a functional consortium of microorganisms attached to the body surfaces and bacteria are embedded in extracellular polymeric substances produced by the microorganisms. This bacterium is nontoxic in the planktonic form, but as a biofilm is highly toxic. In this study, we examined the association between the presence of exo-A gene and antibiotic resistance patterns with biofilm formation in Pseudomonas aeruginosa strains.

  Methods: In this study 110 strains of Pseudomonas aeruginosa isolated from various infections with defined antibiotic resistance patterns were used. The PCR method was used to detect the presence or absence of Exotoxin A gene (exo-A). Ability of biofilm formation was evaluated by spectrophotometry. Association between exo-A gene and antibiotic resistance patterns with biofilms formation was analyzed statistically by Fishers and Chi-square tests.

  Results: exo-A gene was detected in 93 strains (84.5%). Sixty two strains were multidrug resistant and they produced broad spectrum beta-lactamase enzyme. Results showed that, exo-A positive strains had significantly higher ability to biofilm formation in comparison with exo-A negative strains (p<0.05). Also the biofilm formation was significantly higher in multidrug resistant and ESBL producing strains (p<0.05).

  Conclusion: The results of this study indicate that there is a significant association between exo-A gene as well as antibiotic resistance pattern and ESBl producing with biofilm formation in Pseudomonas aeruginosa. Because of importance of biofilms in the pathogenesis of this bacterium, our study could open a new window for investigation of the molecular processes involved in the formation of biofilms.

Parviz Mohajeri , Babak Izadi , Mansour Rezai , Badie Falahi , Hosna Khademi , Roya Ebrahimi ,
Volume 11, Issue 1 (4-2011)

  Background & Objectives: Nowadays, appearance of ESBL producing bacteria is medical problem in the treatment of infections. Uropathogenic Escherichia coli like many other bacteria can produce these types of enzymes. T he assessment of the ESBL production by clinical isolates is not done routinely in laboratories. The aim of this study was to determine the prevalence of ESBL producing E.coli and its antibiotic resistance pattern in Kermanshah.

  Methods: This cross - sectional study was done on 200 Uropathogenic E. coli strains isolated from people in Kermanshah. Sensitivity of isolates to different antibiotics was determined by disk diffusion test and ESBL production was assessed by DDST method.

  Results: The E. coli strains showed high susceptibility to imipenem (100%), amikacin (97%), nitrofurantoin (95.5%), gentamicin (85%), cefepime (75%), ceftazidime (74%), ofloxacin (73.5%), ciprofloxacin, ceftriaxone and aztreonam (71%) and cefotaxime (70%) respectively. The highest resistance was seen to ampicillin (77%), carbenicillin (76%), pipracillin (74%) and SXT (62.5% ). Resistance rate to third generation cephalosporins was 63-75%. Fifty seven isolates (27%) were ESBL producers and 47 isolates (87%) produced all four types of ESBL enzymes.

  Conclusion: There are some similarities and differences in the antibiotic resistance pattern and ESBL production among the isolates in different areas of Iran and other countries. Identification of ESBL producing bacteria and determining its antimicrobial resistance pattern are recommended to effective treatment of infections.

Maryam Adabi, Mahshid Talebi Taher , Leila Arbabi, Mastaneh Afshar , Sara Fathizadeh, Sara Minaeian, Niloofar Moghadam-Marageh, Ali Majidpour ,
Volume 15, Issue 1 (4-2015)

  Background & objectives: Wound infection is a predominant cause of death in burned patients who are clearly at increased risk of nosocomial infections. Pseudomonas aeruginosa is the most common cause of burn infections and is difficult to treat because of having high level of resistance to antibiotics. The aim of this study was to perform isolation, identification and determination of antibiotics resistance pattern of P. aeruginosa strains isolated from wounds of hospitalized burn patient.

  Methods: Biochemical and molecular tests were used for identification of the P. aeruginosa and antibacterial susceptibility test was performed using disk diffusion (Kirby- Bauer) methods. Then, the minimum inhibitory concentration (MIC) was performed for four representatives of different groups of antibiotics.

  Results: Among 94 evaluated strains of P. aeruginosa, 83 isolates (88.3%) were multi drugs resistant. Based on Kirby-Bauer method, the most resistance was seen to cefepime (89.5 %) and among the antibiotics studied to determine the MIC, the most resistance was observed to ciprofloxacin (89 %).

Conclusion: These results indicate high range of resistance to different antibiotics among strains of P. aeruginosa isolated from burn wounds of patients. So, the fast and accurate measurement and evaluation of antibiotic resistance for appropriate antibiotic therapy of burned patients is imperative.

Behnam Mohammadi-Ghalehbin , Hannane Javanpour Heravi , Mohsen Arzanlou, Mohammadreza Sarvi ,
Volume 16, Issue 4 (1-2017)

Background & objectives: Candidiasis is a fungal infection which is caused by Candida spp. Candida albicans is the most common agent of candidiasis. This infection may cause various side effects during pregnancy including prematurity, chorioamnionitis, candidal pneumonia, and systemic candidiasis of infants. This research was conducted for determining the prevalence and antibiotic resistance pattern of Candida spp, collected from pregnant women admitted to health centers in Ardabil, Iran.

Methods: Totally, 408 subjects were included in this study. Demographic data and risk factors were recorded using a questionnaire. Two swab samples were taken from vulvovaginal mucus. One swab was used for preparing smear and direct microscopic examination and the second one used for cultivating the specimen. After identification of Candida spp., antimicrobial resistance pattern was determined by disk diffusion method against Fluconazole, Ketoconazole, Clotrimazole, Nystatin and Amphotericin B. Results were interpreted according to CLSI guidelines. The data were analyzed by χ2 and t-test using SPSS-19.

Results: Out of 408 subjects, 143 cases (35%) were positive for candida spp. The Candida albicans with 119 (83.2%) cases was the most prevalent species followed by Candida glabrata, Candida krusei, Candida parpsilosis and Candida tropicalis.According to disk diffusion test, overall 116 (81.1%) isolates were resistant to Fluconazole, 100 (69.9%) to Ketoconazole, 67 (46.9%) to Clotrimazole and 25 (17.5%) to Amphotericin B. Candida spp. had a highest sensitivity (118, 82.5%) to Nystatin. For Candida albicans 97(81.5%) isolates were resistant to Fluconazole and 99(83.2%) isolates to Nystatin. For Candida glabrata 10 (90.9%) isolates were resistant to Fluconazole, and 9(81.8%) sensitive to Nystatin.

Conclusion: According to the results of this study, vulvovaginal candidiasis is prevalent among pregnant women in Ardabil and isolates were significantly resistant against commonly used antifungal drugs. Nystatin was the most effective against Candida spp. As antibiogram for fungal agents is not routinely performed, the similar periodical studies could be useful for choosing appropriate antibiotics in treatment of vulvovaginal candidiasis. 

Hosseini Fatemeh, Mohammad Kargar,
Volume 17, Issue 2 (7-2017)

Background & objectives: Enterococcus spp. are predominant in the faecal microflora which enter the environment directly or through wastewater. These bacteria play an important role in the development of nosocomial infections due to their ability to acquire resistance genes and their transmission to other bacteria, particularly Staphylococcus aureus. The aim of this study was to identify the prevalence of vancomycin-resistant enterococci (VRE) and to detect van A, van B and van C1/C2 genes in VRE strain isolated from environmental samples of the in southern Fars province.
Methods: This cross-sectional study was carried out on 155 Enterococcus spp isolates collected from environmental samples (hospital wastewaters and surface waters) in different areas of Larestan and Jahrom cities. Isolates were identified and confirmed as Enterococcus spp. using the membrane filtration method, selective growth on Kenner Fecal Streptococcus Agar (KF) medium and biochemical tests. The disk diffusion test and Macro Broth dilution method based on CLSI guidelines were used to determine antimicrobial susceptibility against conventional antibiotics and vancomycin and to measure the minimum inhibitory concentration (MIC), respectively. Finally, the presence of van A, van B and van C1/C2 genes in VRE strains was determined by multiplex PCR technique.
Results: Out of all of Enterococcus spp. isolates, 41 cases (26.45%) were belonged to E.faecalis, 6 cases (3.87%) to E.faecium and 108 cases (69.68%) to non-faecalis and non-faecium. In total, 46 isolates (29.67%) were resistant to vancomycin and 4 isolates showed MIC ≥128 μg/ml. Resistant to all types of antibiotics was observed in 4 isolates (8.70%). Further, 2 isolates (50%) had vanA gene and 2 isolates (50%) had vanB gene, but vanC1/C2 genes were detected in none of them.
Conclusion: The results indicated that the VRE strains are widespread in the studied area, therefore there is an urgent need for prudent use of vancomycin and implementation of control measures to prevent the environmental spread of VRE strains.
Sanaz Habibi, Roya Safarkar, Vahid Rouhi,
Volume 19, Issue 4 (1-2020)

Background & objectives: Methicillin-resistant Staphylococcus aureus is one of the most common causes of nosocomial infections.  The polysaccharide adhesion mechanism encoded by the ica operon generates a direct role in biofilm formation and infection of the bacteria. The aim of this study was to evaluate the frequency of icaA gene in Staphylococcus aureus isolates isolated from clinical specimens of patients admitted to some clinical centers of Rasht.
Methods: This descriptive, cross-sectional study was performed on 100 Staphylococcus aureus isolates from some clinical centers of Rasht in 2019 and confirmatory tests were performed to identify the bacteria. icaA gene identification and its frequency were investigated using molecular methods . The antibiotic resistance pattern against 10 antibiotics and biofilm-forming ability of the isolates were determined using the disk diffusion method and Congo red method respectively.
Results: In the present study, among the 100 studied isolates, the highest drug resistance was related to penicillin, and the lowest antibiotic resistance was belonged to ciprofloxacin. 81 isolates (81%) were resistant to methicillin and 37 isolates (37%) had multiple resistance. Of 37 isolates with multiple resistances, 32 isolates (86.48%) had icaA gene and 24 isolates (64.9%) ،had the ability to produce strong biofilms.
Conclusion: According to the findings of this study, the prevalence of Staphylococcus aureus isolates carrying icaA gene with strong biofilm forming ability and resistance to methicillin, were high. This necessitates the need for serious management of antibiotic administration.

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