Showing 34 results for Staphylococcus Aureus
Katayoon Nofouzi , Alaleh Rakhshanpoor, Reza Asadpour,
Volume 11, Issue 4 (7-2017)
Abstract
ABSTRACT
Background and Objectives: Mastitis caused by Staphylococcus aureus is a widely distributed disease in cattle, goats and sheep. The infection is often subclinical in cattle, leading to reduced milk production and quality, but acute catarrhal or even gangrenous inflammation may also occur. The aim of this study was to investigate resistance of S. aureus isolates from bovine subclinical mastitis to a number of antibiotics.
Methods: Milk samples were collected from 120 cows in different regions of Tabriz, Iran. Milk samples were cultured and bacteriological identification was performed. Antimicrobial susceptibility of the isolates was assessed by determining minimum inhibitory concentration. Plasmid DNA was extracted by an alkaline lysis method.
Results: The highest frequency of resistance was observed against gentamicin (100%) and β- lactam antibiotics including amoxicillin (96%), ampicillin (40%) and penicillin (96%). The isolates mostly contained large plasmids, which might harbor acquired antibiotic resistance.
Conclusion: The results confirm the high frequency of antibiotic resistance among staphylococci isolated from bovine subclinical mastitis.
Keywords: Anti-infective Agents, Cattle, Staphylococcus Aureus, Mastitis, Plasmids.
Bahareh Charmi Far , Saman Mahdavi,
Volume 11, Issue 5 (9-2017)
Abstract
ABSTRACT
Background and Objectives: Several virulence factors are involved in the pathogenesis of Staphylococcus aureus. Surface proteins such as collagen binding proteins (Cna) and fibronectin-binding proteins (FnBP) are important factors in adhesion and invasion of S. aureus. The aim of this study was to evaluate the frequency of adherence genes cna, fnbA and fnbB S. aureus isolates from traditional cheese.
Methods: All 22 isolates tested were identified as S. aureus. The isolates were tested for the presence of adherence genes cna, fnbA and fnbB using specific primers in polymerase chain reaction assay.
Results: Six isolates (27.27%) were positive for the can gene. Of the 22 isolates studied, one isolate was positive for fnbA and one was positive for the fnbB. Co-presence of the genes examined was not observed in any of the isolates.
Conclusion: The results indicate the weak biofilm formation ability of the S. aureus isolates from traditional cheese.
Keywords: Staphylococcus aureus, Biofilm, Genes, Cheese.
Reza Hakimi Alni , Abdolmajid Mohammadzadeh , Pezhman Mahmoodi , Mohammad Yousef Alikhani ,
Volume 11, Issue 6 (11-2017)
Abstract
ABSTRACT
Background and Objectives: Determining the genetic relationship between S. aureus isolates is important for epidemiological surveillance and control of infections caused by this bacterium. The present study was conducted to determine polymorphisms of coagulase gene (coa) among S. aureus isolates from pastry and cheese samples using restriction fragment length polymorphism (RFLP) analysis.
Methods: Overall, 65 S. aureus isolated from pastry (n=45) and cheese (n=20) samples were examined for the coa gene by polymerase chain reaction (PCR). PCR products were digested with AluI enzyme and the products were assessed using gel electrophoresis.
Results: Except for two isolates, all isolates were positive in coa-PCR and produced four different PCR products, with molecular sizes ranging from 570 to 970 bp. Overall; five distinct RFLP patterns were detected (I-V). Although pattern types I and III were present in isolates from both samples, types I and IV were mainly present in isolates from cheese and pastry samples, respectively.
Conclusion: PCR-RFLP analysis of the coa gene indicates that S. aureus isolates from pastry and cheese samples may be originated from different sources. However, as one pattern type was predominant in each group, it can be concluded that majority of the isolates may have the same origin.
Keywords: Staphylococcus aureus, PCR-RFLP, Coagulase, Pastry, Cheese.
Abolfazl Khandan Del , Ania Ahani Azari , Ailar Jamalli, Ezzat Allah Ghaemi,
Volume 12, Issue 3 (5-2018)
Abstract
ABSTRACT
Background and Objectives: Staphylococcus aureus is one of the most common causes of morbidity and mortality among intensive care unit (ICU) patients. Nasal carriage is one of the main routs of
S. aureus transmission between hospital personnel and patients. The objective of this study was to evaluate the efficacy of mupirocin ointment in eradication of nasal carriage of
S. aureus in the ICU staff and patients of Panje-Azar hospital in Gorgan, Iran.
Methods: In the first three months of the study (January to March), the prevalence of
S. aureus among ICU patients was determined by routine microbiological and biochemical testing. Nasal samples were taken from ICU staff and all patients recently admitted to the ICU. Mupirocin nasal ointment (2%) was applied for treatment of
S. aureus nasal carriers. Post-treatment sampling was done after five weeks. During the next three months, the presence of
S. aureus and rate of resistance to methicillin was evaluated in new patients admitted to the ICU using the method used previously.
Results: Of 60 samples from the ICU staff, seven (11.7%) samples were positive for
S. aureus. Moreover, of 240 samples from the ICU patients, two samples were found as
S. aureus-positive. Of the nine
S. aureus-positive isolates, only two (22.2%) were methicillin-resistant
S. aureus (MRSA). In the pre-intervention sampling, only five samples (2.8%) were identified as
S. aureus, two of which were MRSA. However, treatment with mupirocin ointment eradicated nasal carriage of
S. aureus and no isolate was found after the intervention.
Conclusion: Our finding showed that mupirocin nasal ointment is highly effective in eradication of
S. aureus nasal carriage and subsequently contribute to reduction in frequency of nosocomial infections in the ICU.
Keywords: Intensive Care Units, Mupirocin, Nasal,
Staphylococcus aureus.
Azizollah Ebrahimi, Younes Daryalal, Mohamadreza Mahzounieh, Sharareh Lotfalian,
Volume 12, Issue 4 (7-2018)
Abstract
ABSTRACT
Background and Objectives: Silver nanoparticles (AgNPs) have physical and surface properties that could threaten human and environmental health. AgNPs are classified as ‘very toxic’ to eukaryotic organisms and are less toxic to bacteria. The aim of the present study was to study the effects of different sub-minimum inhibitory concentrations (MICs) of AgNPs on some virulence factors of Staphylococcus aureus as a pathogenic bacterial model.
Methods: Tube double serial dilution method was used to determine MIC of AgNPs against standard strain and ten field isolates of S. aureus. Tube cultures of isolates in LB broth were supplemented with different concentrations of AgNPs and were incubated at 37 °C with constant shaking under aerobic conditions. Samples from each tube were streaked on blood agar plates and assay for hemolysins, coagulase and DNase production were performed.
Results: The MIC of AgNPs against all examined isolates was determined as 50 µg/mL. The results showed that 1/2, 1/4 and 1/8 MIC of AgNPs had no negative effect on DNase and coagulase production but inhibited alpha- and beta-hemolysin production in most isolates (64-91%). In addition, production of delta-hemolysin was inhibited by 1/2 MIC of AgNPs.
Conclusion: The effects of sub-MIC of AgNPs on bacterial growth appear at 4-8 hours post-exposure and then the bacteria follow a normal growth trend. This toxic effect may affect ecosystems species.
Keywords: Silver particles, Minimum inhibitory concentration, Virulence factors, Staphylococcus aureus.
Hoorieh Hoseinpoor , Davoud Esmaeili ,
Volume 13, Issue 3 (5-2019)
Abstract
ABSTRACT
Background and Objectives: In recent years, infections caused by antibiotic-resistant strains of Staphylococcus aureus have become a major health issue. It has been suggested that the extract or essential oil of cinnamon tree has antibacterial properties. In this study, we investigated the antibacterial effects of polyurethane-cinnamon nanofibers against clinical isolates of S. aureus.
Methods: Polyurethane-Cinnamomum zeylanicum nanofiber scaffolds were synthesized. Polyurethane nanofiber and cinnamon polymers were also used to prepare the scaffold under the electrospinning process. Infrared spectroscopy, electron microscopy and mechanical tensile test were utilized to assess the scaffolds. Minimum inhibitory concentration of the nanofiber against the bacteria was determined using the broth dilution method according to the Clinical & Laboratory Standards Institute guidelines.
Results: The results of antibiogram test showed that all tested disks were susceptible to S. aureus. Diameter of growth inhibition zone for polyurethane-cinnamon 10% was 41 mm. Minimum inhibitory concentration of the nanofiber against S. aureus isolates was 0.02 μg/mL.
Conclusion: We demonstrated that the polyurethane-cinnamon nanofiber has favorable antibacterial effects against clinical isolates of S. aureus. It is recommended to conduct further studies on the antibacterial effects of this nanofiber on other bacteria.
Keywords: Staphylococcus aureus, Cinnamon, Nano fiber.
Mohammad Habibi Juybari , Hamidreza Pordeli , Saeid Mikaeili ,
Volume 13, Issue 3 (5-2019)
Abstract
ABSTRACT
Background and Objectives: Schiff base ligands are prepared via the condensation reaction of 1, 10- dimethyl–phenantroline aldehyde derivative with some nitrogen donor ligands, such as benzene ring that have different functional groups (-OH, -SH, -OCH3,-CH2OH, -Br) in acetonitrile. Recent studies suggest that Schiff bases might have antibacterial activity. Therefore, we aimed to synthesize new Schiff base complexes and evaluate their antibacterial activity against a number of Gram-positive and Gram-negative bacteria.
Methods: Schiff base ligands and their complexes were characterized by mass spectrometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy. The in vitro antibacterial activity of the Schiff base ligands and metal ions against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was evaluated by determining minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) using the broth dilution method.
Results: All synthesized Schiff bases exhibited favorable antibacterial activity against the tested microorganism, but the antibacterial effect of compounds 3OH and 3SH was more significant than that of other compounds.
Conclusion: Compound 3EOH has favorable antibacterial activity against the tested bacteria.
Keywords: Schiff bases, antibacterial effect, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa.
Abolfazl Khandandel , Hami Kaboosi , Ailar Jamalli , Fatemeh Peyravii Ghadikolaii ,
Volume 13, Issue 4 (7-2019)
Abstract
Background and Objectives:
Staphylococcus aureus is a common cause of nosocomial infections. The ability of
S. aureus to form biofilm and acquire antimicrobial resistance has made this organism a major health problem. In this study, we investigate the biofilm-forming ability of
S. aureus isolates from clinical samples.
Methods: Sixty
S. aureus isolates from clinical specimens were collected from the 5th Azar Hospital of Gorgan (Iran) in 2018. The isolates were identified using conventional methods including Gram staining and biochemical tests (catalase and coagulase). Biofilm formation by
S. aureus isolates was evaluated using a microplate-based method.
Results: Of 60
S. aureus isolates, 47 (78.3%) strains were identified as biofilm-forming and 13 (21.7%) strains were non-biofilm-forming.
Conclusion: The high prevalence of biofilm-producing
S. aureus isolates in the 5
th Azar hospital of Gorgan could pose a major health challenge with serious consequences for hospitalized patients. Therefore, it is crucial to disinfect and sterilize hospital surfaces and equipment effectively to minimize the risk of contamination and spread of bacteria in the hospital settings.
Keywords: Biofilms,
Staphylococcus aureus, sample.
Ali Asghar Ayatollahi, Abolfazl Khandan Del, Ailar Jamalli, Khashayar Shahin, Ania Ahani Azari,
Volume 14, Issue 1 (1-2020)
Abstract
Background and objectives: Staphylococcus aureus is a frequent cause of hospital- and community-associated infections on a global scale. This organism is responsible for causing an extensive range of diseases and many of them are capable of biofilm formation for their survival. By this method, treatment of them with antibiotics become very difficult and antibiotic resistance is another rising concern.
Material and Methods: The clinical samples were collected and examined for Staphylococcus aureus by microbiological and biochemical tests. Then, the biofilm formation in Staphylococcus aureus isolates was detected by microtiter plate. Using SYBR Green Real-Time PCR, the expression of PSM was determined.
Results: A total of 60 strains of Staphylococcus aureus were isolated from clinical isolates. Of them, 47 strains (78.3%) were identified biofilm producing and the others were considered negative for biofilm formation. After real-time PCR testing to detect PSM, it was determined that 100% of the strains were positive for biofilms and PSM genes. The results of phenotypic and genotypic tests of biofilm were closely related to each other and the expression of PSM B gene was 80%. It was found that 100% of strains were biofilm producing and PSM B gene was present in 78.3% (47 strains) of them.
Conclusion: The prevalence of biofilm production in Staphylococcus aureus strains isolated from clinical samples was high, so it is highly important to monitor the prevalence of these organisms in hospitals and community as well as their antimicrobial resistance.
Ezzat Allah Ghaemi, Fahimeh Azadi, Naeme Javid, Hanieh Bagheri,
Volume 14, Issue 4 (7-2020)
Abstract
Background and objectives: Drug resistance in Staphylococcus aureus and Escherichia coli, as severe pathogenic bacteria, has become a health challenge. However, nanoparticles have been introduced as effective candidates for their eradication. In this study, we investigated presence of genes involved in conferring resistance to silver nanoparticles in S. aureus and E. coli isolates and evaluated its association with minimal inhibitory concentration (MIC) of the nanoparticles against these isolates.
Methods: The MIC of silver nanoparticles against 121 clinical isolates of E. coli and 183 S. aureus isolates was assessed by broth microdilution assay. Presence and expression of the silver resistance genes (silE, silR/S) in the isolates were investigated by PCR and real-time PCR, respectively.
Results: The silE gene was found in three (1.6%) S. aureus and four (3%) E. coli isolates. MIC of silver nanoparticles against S. aureus isolates with the silE gene was 1, 2 and 8 µg/ml. Moreover, the MIC of the nanoparticles against silE-positive E. coli isolates was 16 μg/ml in three cases and 8 μg/ml in one case. None of the S. aureus isolates contained the silR/S gene, but presence of both silE and silR/S was confirmed in two E. coli isolates. Real-time PCR showed no sil expression in the isolates containing the resistance genes.
Conclusion: The frequency of the silver resistance genes among S. aureus and E. coli isolates is very low. There is no relationship between presence of the resistance genes and the MIC value of silver nanoparticles.
Dr Mohsen Ebrahimi, Dr Hassan Esmaeili,
Volume 15, Issue 6 (11-2021)
Abstract
Infective endocarditis is rare in children but can cause significant morbidity and mortality. Streptococcus and Staphylococcus species are the leading causes of this disease. Staphylococcus is more common in people with underlying heart disease, and Streptococcus viridans is more common in people who have had a dental procedure. In general, any fever of unknown origin in children with an underlying heart problem should be carefully evaluated for endocarditis, and empiric therapy should be performed. The main symptoms of the disease include fever, new murmur, deterioration of the previous murmur, hematuria, embolic events, splenomegaly, bleeding splinter, Osler's nodes, Janeway lesion, and Roth spots. One of the important complications of infective endocarditis is cerebrovascular event and stroke. Herein, we describe a 6-year-old girl presented with fever and skin lesions and no history of underlying heart problem or dental procedure. The patient expired after three days of mitral valve infection with S. aureus.
Mobina Hosseini, Meysam Hasannejad-Bibalan, Tofigh Yaghoubi, Mohammadreza Mobayen, Parisa Khoshdoz, Sara Khoshdoz, Niloofar Faraji, Hadi Sedigh Ebrahim-Saraie,
Volume 15, Issue 6 (11-2021)
Abstract
Background and objectives: Bacterial contamination of wounds is a serious problem, particularly in burn patients. Gram-positive bacteria are the predominant cause of infection in newly hospitalized burn cases. This study aimed to survey the prevalence and antibiotic resistance pattern of gram-positive bacterial isolates among burn patients in Rasht, North of Iran.
Methods: This cross-sectional study was conducted on burn patients with a positive culture for gram-positive isolates who were hospitalized in the Velayat Burn Center in Rasht, North of Iran, during 2017-2020. The isolates were identified using standard microbiological methods. Moreover, the antibiotic resistance pattern was determined by the disk diffusion method.
Results: During the study period, 671 bacterial cultures were obtained, of which a total of 16 gram-positive isolates were taken from the patients. The frequency of coagulase-negative staphylococci (CoNS), Staphylococcus aureus, and Enterococcus spp. was 68.7%, 18.8%, and 12.5%, respectively. In addition, the highest rate of resistance in CoNS isolates was against trimethoprim/sulfamethoxazole. The highest rate of resistant among S. aureus isolates was recorded against penicillin. Moreover, Enterococcus faecalis isolates showed a high level of resistance to ampicillin, erythromycin, tetracycline, gentamicin, and ciprofloxacin. All isolates were susceptible to teicoplanin. Moreover, the frequency of methicillin-resistant S. aureus isolates was 66.7%.
Conclusion: Given the increasing prevalence of drug-resistant strains, especially in susceptible burn patients, it is imperative to analyze the bacterial etiology of nosocomial infections periodically and epidemiologically.
Mahsa Aghaei , Leila Asadpour , Amir Arasteh,
Volume 18, Issue 4 (7-2024)
Abstract
Background: Staphylococcus aureus is one of the most common agents of nosocomial infection worldwide. Methicillin-resistant and biofilm-associated infections of this bacterium have become a clinical concern in patients. This research aimed to identify biofilm-forming ability and accessory gene regulator (Agr) - specific group of clinical isolates of methicillin-resistant S. aureus (MRSA) in Northern Iran.
Methods: In 2021, a total of 200 clinical isolates were identified as S. aureus by biochemical tests. The disk diffusion method was used to examine the antibiotic resistance of isolates and the microplate method was applied to investigate the biofilm production capability. In addition, the PCR method was used to determine the frequency of biofilm-associated genes and Agr typing of MRSA isolates. P £ 0.05 was considered significant.
Results: Overall, 62.5% of isolates were methicillin-resistant and 75% were multiple antibiotic-resistant. Biofilm-forming ability was detected in 99 (79.2%) methicillin-resistant isolates in which icaA and icaD were found in 85% and 78% of biofilm-producing isolates, respectively. Type 1 of the Agr gene was the most common type among methicillin-resistant isolates. The frequency of biofilm-associated genes showed a significant association with MDR phenotype and the presence of Agr locus (P £ 0.05).
Conclusion: The present findings indicate a high frequency of biofilm and antibacterial resistance in methicillin-resistant S. aureus isolates in Guilan Province. These findings suggest reliable and rapid identification of biofilm-forming MRSA strains to prevent the spread of these bacteria.
Syed Majid Ali, Jalila Qayoom, Talat Masoodi, Azhar Shafi, Arshi Syed,
Volume 18, Issue 5 (9-2024)
Abstract
Background: Post-operative wound infection has been a problem since surgery was started as a treatment modality and is the third most common cause of nosocomial infections with a reported incidence rate of 14-16%. This study aimed to investigate the prevalence, isolate and identify aerobic pathogenic bacteria from surgical site infections (SSI) and to determine the antibiotic susceptibility testing (AST) pattern of pathogenic bacteria.
Methods: This study was conducted at the Department of Microbiology SKIMS-Medical College, Bemina Srinagar, over a period of six months from November 2021 to April 2022. In the study, 210 samples from patients with SSI were included. Isolation, identification, and AST of the isolates were performed by standard microbiological techniques.
Results: Out of 210 SSI samples, 163 bacterial isolates were recovered and infection rate was more in 21-30 years age group (24.2%). Gram-negative bacteria were isolated in 50.4% (82/163) cases and E. coli was the most common organism (59.75%, 49/82). Gram-negative bacteria were sensitive to imipenem and none were resistant to polymyxin-B and colistin. E. coli was mostly resistant to cefoperazone, Acinetobacter and Klebsiella species were resistant to ceftazidime, Pseudomonas and Citrobacter were resistant to ceftriaxone. Gram-positive bacteria constituted 49.6% (81/163) and Methicillin-resistant Staphylococcus aureus (MRSA) was a frequently isolated species (66.6%, 54/81). MRSA- and methicillin-sensitive Staphylococcus aureus (MSSA) were mostly sensitive to amikacin, gentamycin, and tetracycline. Moreover, none of the Gram-positive isolates were resistant to linezolid, vancomycin, and teicoplanin. Enterococcus spp was mostly resistant to gentamycin.
Conclusion: This study developed an insight into post-operative wound infections and their incidence, organisms’ prevalence, and their antibiogram. Culture positivity in suspected cases of SSI was high (77.6%). MRSA and E. coli were frequently isolated from Gram-positive and Gram-negative bacteria.
