scholarly journals Mutation-Based Antibiotic Resistance Mechanism in Methicillin-Resistant Staphylococcus aureus Clinical Isolates

2021 ◽  
Vol 14 (5) ◽  
pp. 420
Author(s):  
Tanveer Ali ◽  
Abdul Basit ◽  
Asad Mustafa Karim ◽  
Jung-Hun Lee ◽  
Jeong-Ho Jeon ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Active Site ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Meca Gene ◽  
Resistance Mechanism ◽  
Ligand Docking ◽  
Clinical Samples ◽  
Allosteric Site ◽  
Methicillin Resistant

β-Lactam antibiotics target penicillin-binding proteins and inhibit the synthesis of peptidoglycan, a crucial step in cell wall biosynthesis. Staphylococcus aureus acquires resistance against β-lactam antibiotics by producing a penicillin-binding protein 2a (PBP2a), encoded by the mecA gene. PBP2a participates in peptidoglycan biosynthesis and exhibits a poor affinity towards β-lactam antibiotics. The current study was performed to determine the diversity and the role of missense mutations of PBP2a in the antibiotic resistance mechanism. The methicillin-resistant Staphylococcus aureus (MRSA) isolates from clinical samples were identified using phenotypic and genotypic techniques. The highest frequency (60%, 18 out of 30) of MRSA was observed in wound specimens. Sequence variation analysis of the mecA gene showed four amino acid substitutions (i.e., E239K, E239R, G246E, and E447K). The E239R mutation was found to be novel. The protein-ligand docking results showed that the E239R mutation in the allosteric site of PBP2a induces conformational changes in the active site and, thus, hinders its interaction with cefoxitin. Therefore, the present report indicates that mutation in the allosteric site of PBP2a provides a more closed active site conformation than wide-type PBP2a and then causes the high-level resistance to cefoxitin.

scholarly journals Antibiotic resistance pattern of Staphylococcus aureus with reference to MRSA isolates from pediatric patients

2019 ◽  
Author(s):  
Raja Ram Gurung ◽  
Prashanna Maharjan ◽  
Ganga GC
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Pediatric Patients ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Current Status ◽  
Clinical Samples ◽  
Resistance Pattern ◽  
Isolation And Identification ◽  
Cross Sectional ◽  
Methicillin Resistant

Abstract Background: Staphylococcus aureus is one of the important superbugs distributed throughout the world. It causes minor skin infections to severe complications including nosocomial infections in both hospitals and community settings. These strains have multi-drug resistant property. Hence, they are difficult to manage which increase health-related costs and simultaneously intensifying the need for new antibiotics. The extent of Methicillin-Resistant Staphylococcus aureus (MRSA) in children is largely unknown. The study determines the current status of S. aureus and MRSA causing various infections in pediatric patients visiting International Friendship Children’s Hospital (IFCH). Methods: A cross-sectional study was conducted among patients visiting a hospital. Various clinical specimens were aseptically collected and processed according to standard microbiological procedures. Isolation and identification of S. aureus were done by microscopy, mannitol fermentation, and coagulase positivity. All identified S. aureus isolates subjected to in-vitro antibiogram by Kirby-Bauer disc diffusion technique adopting Clinical and Laboratory Standards Institute (CLSI) guideline. Isolates resistant to cefoxitin were considered to be MRSA. Whereas, isolates produced D-shaped inhibition zone around clindamycin when kept near erythromycin were considered to be Inducible Clindamycin Resistant (ICR). Results: 672 various types of clinical samples were processed from the microbiology laboratory from June and November 2015. Out of 300 culture positive samples, 52 (17.3%) were S. aureus isolates, among them 39 (75.0%) were found to be MRSA. The D-test showed that Macrolide-Lincosamide-Streptogramin-B (MLSB) phenotype was 15.4%. Conclusion: The study shows the MRSA occurrence is prevalent in pediatric patients and newer classes’ drugs are found more effective than β-lactam drugs to treat S. aureus infection. However, restriction on the indiscriminate use of such drugs may be an effective strategy to control the drug resistance. Keywords: Methicillin-Resistant Staphylococcus aureus (MRSA), Macrolide-Lincosamide-Streptogramin B (MLSB) phenotype, Inducible Clindamycin Resistant (ICR) test or D-zone test, Antibiotic resistance, Nepal

Evaluation of antibiotic resistance pattern and mecA gene frequency in methicillin-resistant Staphylococcus aureus strains collected from clinical specimens in Marand hospital and treatment centers, Iran

2021 ◽  
Author(s):  
Abolfazl Jafari-Sales ◽  
Zahra Sadeghi Deylamdeh ◽  
Afsoon Shariat
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Meca Gene ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Disk Diffusion Method ◽  
Methicillin Resistant ◽  
Medical Centers ◽  
Wide Range

Introduction: Staphylococcus aureus causes a wide range of infections and as a multivalent pathogen is one of the causative agents of nosocomial and community infections. Therefore, the aim of this study was to identify and determine the pattern of antibiotic resistance of methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients in hospitals and medical centers in Marand city and also to evaluate the presence of mecA gene. Materials and Methods: In this cross-sectional descriptive study, 385 samples of S. aureus were collected from different clinical samples of patients in hospitals and medical centers of Marand city. S. aureus was identified using standard biochemical methods.  Methicillin resistance was determined by disk diffusion method in the presence of oxacillin and cefoxitin. The pattern of antibiotic resistance of the strains was determined by disk diffusion method and according to CLSI recommendation and also PCR method was used to evaluate the frequency of MecA gene. Results: In the present study, out of 385 samples of S. aureus, 215 (55.84%) samples were methicillin resistant. PCR results for mecA gene showed that 110 samples had mecA gene.  The highest antibiotic resistance was observed against penicillin (100%) and erythromycin (83.63%). Most MRSA were isolated from urine and wound samples. Conclusion: The results of this study indicate the prevalence of methicillin-resistant species and also the increase in antibiotic resistance of MRSA to various antibiotics.  Therefore, in order to prevent increased resistance to other antibiotics, it is recommended to avoid inappropriate use of antibiotics.

scholarly journals Evaluation of MRSA Chrome agar for the detection of methicillin resistant Staphylococcus aureus

2014 ◽  
Vol 7 (1) ◽  
pp. 1-4
Author(s):  
Durdana Chowdhury ◽  
Sanya Tahmina Jhora ◽  
Tarek Mahbub Khan ◽  
Sadia Afroz
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Meca Gene ◽  
Clinical Samples ◽  
Clinical Microbiology Laboratory ◽  
Blue Color ◽  
Disc Diffusion ◽  
Diffusion Test ◽  
Gold Standard Method ◽  
Methicillin Resistant

The aim of this study was to evaluate the efficacy of MRSA Chrome agar to detect methicillin resistant Staphylococcus aureus (MRSA) and compare it with 1?g oxacillin disc diffusion tests and detection of mecA gene by PCR. A total 116 Staphylococcus aureus (S. aureus), isolated from various clinical samples, were obtained from three tertiary care hospitals of Dhaka city. S. aureus was identified by colony characters, Gram stain and standard biochemical procedures. MRSA was detected by susceptibility to 1?g oxacillin disc, growth of denim blue color colonies of S. aureus on the Brilliance MRSA Chrome agar at 24 and 48 hours of incubation. PCR was performed for amplification of mecA gene as a gold standard method. Out of 116 isolated S. aureus, 33 (28.44%) were MRSA by oxacillin disc diffusion test where mecA gene was detected in 28 strains. On MRSA Chrome agar, 29 (25.0%) S. aureus produced denim blue colonies at 24 hours, of which 28 isolates possessed mecA gene. At 48 hours incubation, an additional 4 isolates yielded denim blue colonies from which mecA gene could not be identified. All the strains of S. aureus that produced denim blue colonies at 24 and 48 hours were resistant to oxacillin. The sensitivity, specificity and accuracy of oxacillin disc diffusion test were 100%, 94.31% and 95.68% and Chrome agar at 24 hours were 100%, 98.86% and 99.13% respectively. Thus MRSA Chrome agar could be good choice in clinical microbiology laboratory for rapid and accurate identification of MRSA. DOI: http://dx.doi.org/10.3329/imcj.v7i1.17697 Ibrahim Med. Coll. J. 2013; 7(1): 1-4

scholarly journals Prevalence and Antibiotic Resistance Mechanisms of Methicillin-Resistant Staphylococcus aureus isolates from Selected Hospitals in Ashanti Region, Ghana.

2021 ◽  
Author(s):  
Crystal Ngofi Zumbi ◽  
Vivian Etsiapa Boamah ◽  
Yaw Duah Boakye ◽  
Hayford Odoi ◽  
Christian Agyare
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Health Problem ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Efflux Pump ◽  
Meca Gene ◽  
Resistance Mechanisms ◽  
Diffusion Method ◽  
Methicillin Resistant ◽  
Ashanti Region

Abstract Background: Antibiotic resistance in bacteria has long been recognized as a major health problem occurring worldwide. The emergence of methicillin-resistant Staphylococcus aureus (MRSA) remains a global health problem. MRSA is reported as one of the leading pathogens involved in increased rates of morbidity and mortality amongst patients in Ghana. This study determined the prevalence and resistance mechanisms of MRSA isolated from patients in selected hospitals in the Ashanti Region of Ghana. Antibiograms of the isolates were determined using the Kirby-Bauer disk diffusion method. Antibiotic resistance genes (mecA and mecC) were detected and efflux pump activity assessed using polymerase chain reaction (PCR) and microbroth dilution methods, respectively. Results: Out of 626 samples obtained from patients, S. aureus was identified in 68, representing 10.9%. Multidrug resistance (MDR) was observed in 46 (67.6%) of the S. aureus isolates of which 28 (60.9%) were Methicillin Resistant Staphylococcus aureus (MRSA). The MRSA isolates showed higher susceptibility to trimethoprim-sulfamethoxazole (50%) and higher resistance to oxacillin and cefoxitin (100%). mecA gene was identified in 9 (32.1%) of the MRSA isolates whereas mecC gene was absent in all the isolates. The isolates did not exhibit any multiple efflux pump activities. Conclusion: The prevalence of MDR-MRSA in S. aureus infections at healthcare facilities in the Ashanti region was found to be high. The presence of the mecA gene was identified as a possible mechanism responsible for resistance in the MRSA isolates.

scholarly journals Susceptibility and molecular characterization of mec A- and mec B-positive community acquired methicillin-resistant Staphylococcus aureus isolates from students

2021 ◽  
Vol 18 (2) ◽  
pp. 155-171
Author(s):  
Patrick O. Olorunfemi ◽  
Ndidi C. Ngwuluka ◽  
Josiah A. Onaolapo ◽  
Yakubu K.E. Ibrahim
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Molecular Characterization ◽  
Resistance Genes ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Meca Gene ◽  
Public Health Importance ◽  
Methicillin Resistant ◽  
Spa Gene

Staphylococcus aureus is an organism of great public health importance. It is widely studied because it is virulent, causes life threatening disease and has ability to adapt to diverse environmental conditions and so develops resistance to antibiotics easily. As a result, there is a need for surveillance of its antibiotic resistance and resistance genes. The susceptibility and molecular characterization of methicillin resistant Staphylococcus aureus recovered from urine samples of healthy students were undertaken. Standard procedures were employed for isolation, identification, susceptibility, and polymerase chain reaction analyses. Out of 217 samples collected, 73 were confirmed Staphylococcus aureus. Most of the isolates were susceptible to ciprofloxacin and vancomycin followed by gentamicin and co-trimoxazole and least susceptible to penicillin, cefotaxime, ofloxacin and cefoxitin. Thirty-two (32) isolates were resistant to 5 antibiotics while 3 isolates were resistant to the 11 antibiotics used in this study. Sixteen phenotypically methicillin resistant isolates contained mecA gene while ten of the isolates also showed the presence of mecB gene. The characteristic Sa442 and nuc genes of Staphylococcus aureus and the presence of spa gene confirmed MRSA. Continous surveillance for antibiotic resistance and resistance genes is paramount at local, regional and national levels. Surveillance data will assist in implementing interventions. Keywords: Antibiotic resistance; Methicillin-resistant Staphylococcus aureus, mecA, mecB, CA-MRSA; Surveillance

scholarly journals Isolation of mecC Gene carrying Methicillin Resistant Staphylococcus aureus in Clinical Samples from a Tertiary Care Institute, Northern India

2021 ◽  
Author(s):  
Nargis Bali ◽  
Biswajyoti Borkakoty ◽  
Humaira Bashir ◽  
Shaista Nazir ◽  
Sayim Wani ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antimicrobial Agents ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Tertiary Care ◽  
Meca Gene ◽  
Clinical Isolates ◽  
Clinical Samples ◽  
Biochemical Tests ◽  
Jammu And Kashmir ◽  
Methicillin Resistant

Introduction: The MecC Methicillin Resistant Staphylococcus aureus (MRSA) after its initial recovery in 2007 has been reported with varying frequency from different parts of the world. These isolates assume importance due to the fact that with routine testing platforms available for the detection of MRSA they can be misidentified as being methicillin sensitive which can adversely affect the treatment and outcome of infections due to MRSA harbouring the mecC gene. Aim: To evaluate mecC gene carrying MRSA in clinical isolates. Materials and Methods: This retrospective study was conducted in the Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India for a period of three months (May-July 2020). A total of 102 laboratory confirmed isolates of MRSA (based on biochemical tests and cefoxitin disc diffusion results) were subjected to screening for the presence of mecA and mecC gene by Polymerase Chain Reaction (PCR). Deoxyribonucleic Acid (DNA) was extracted using an in house extraction method following which mecA and mecC were amplified in a total reaction volume of 25 μL using 2x PCR master mix, 5 μL of template and 1 μL (0.4 μM final concentration) each of reverse and forward primers specific for the above mentioned genes. Statistical analysis was done using Statistical Package for the Social Sciences (SPSS) software v24.0. Results: All the isolates were confirmed as being methicillin resistant with 96.1% isolates carrying the mecA gene and 3.9% carrying the mecC gene. The mecC MRSA were recovered from pus, swab and endotracheal tip in middle aged men. One of the patient from whose sample mecC MRSA was recovered was suffering from hypertension, diabetes and renal faliure. MRSA exhibited high resistance to all the antimicrobial agents tested however all of them were sensitive to vancomycin and linezolid. Conclusion: The presence of mecC gene in clinical isolates of MRSA is a cause of concern and calls for an extensive and continuous surveillance of such isolates as they can in future be implicated in causing severe human infections.

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