scholarly journals Comparison of Cefoxitin and Oxacillin disc diffusion test for the detection of mecA mediated methicillin resistance in Staphylococcus aureus

2013 ◽  
Vol 7 (1) ◽  
pp. 07-10 ◽  
Author(s):  
Durdana Chowdhury ◽  
Sanya Tahmina Jhora ◽  
Shika Paul ◽  
Tarek Mahbub Khan ◽  
Mili Rani Saha ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Susceptibility Testing ◽  
Methicillin Resistance ◽  
Meca Gene ◽  
Clinical Samples ◽  
Disc Diffusion ◽  
Standard Laboratory ◽  
Diffusion Test ◽  
Laboratory Procedure ◽  
Gold Standard Method

The study was designed to evaluate the efficacy of cefoxitin disc diffusion test to detect methicillin resistance in Staphylococcus aureus and compare it with oxacillin disc diffusion test and detection of mecA gene by PCR.  A total 116 S. aureus were isolated from clinical samples, collected from SSMC&MH, BIRDEM and NMC hospital, and was isolated by culture and identified by standard laboratory procedure. Antibiotic susceptibility testing was performed by oxacillin (1µg) and cefoxitin (30 µg) discs. PCR for amplification of mecA gene was performed as a gold standard method. Out of 116 isolates, 28 were PCR positive, 33 and 31 were oxacillin and cefoxitin resistant respectively. The sensitivity and specificity for the detection of MRSA was 100% and 94.31%inoxacillin disc diffusion test, and 96.42% and 95.45%in cefoxitin disc diffusion test respectively. Specificity is higher (95.45%) in cefoxitin disc diffusion test than oxacillin disc diffusion test in the detection of MRSA. Use of disc diffusion tests for both oxacillin and cefoxitin can help in more accurate prediction of methicillin resistance than single test, especially in centers which are not equipped to carry out more sophisticated tests for the detection of MRSA.DOI: http://dx.doi.org/10.3329/bjmm.v7i1.19314 Bangladesh J Med Microbiol 2013; 07(01): 7-10

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 Evaluation of cefoxitin disc diffusion test as a rapid phenotypic method for detection of methicillin resistance

2021 ◽  
Vol 8 (3) ◽  
pp. 215-218
Author(s):  
Anandkumar H ◽  
Jyothi U S ◽  
Rajeshwari R S
Keyword(s):  
Methicillin Resistance ◽  
Surrogate Marker ◽  
Regulatory System ◽  
Hospital Environment ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Disc Diffusion ◽  
Diffusion Test ◽  
Potent Inducer ◽  
Gold Standard Method

: Accuracy and promptness in the detection of methicillin resistance are of key importance in ensuring correct antibiotic treatment in infected patients and control of MR staphylococci in the hospital environment. The aim of this study was to detect MRSA phenotypically by oxacillin screen agar and Oxacillin MIC method and to evaluate cefoxitin disc diffusion test as a screening tool for MRSA detection. In the present study, a total of 50 isolates of from various clinical samples collected were used for the detection of Methicillin resistant (MRSA). Methicillin resistance was determined by oxacillin disc diffusion, cefoxitin disc diffusion the oxacillin screen agar test and MIC. Out of 50 isolates 21 (42%) isolates were detected as MRSA based on MIC method, which is considered as gold standard method for the detection of MRSA. All the isolates of MRSA were 100% susceptible to vancomycin and linezolid. rnIn the present study, cefoxitin diffusion method has given 100% sensitivity and specificity in concordance with MIC method. However, the oxacillin screen agar method showed 95.24% sensitivity and 96.55% specificity. As per our study and previous reports elsewhere on phenotypic detection of MRSA, cefoxitin is more potent inducer of the regulatory system and an accurate surrogate marker for the detection of MRSA in the routine susceptibility testing.

scholarly journals Isolation and Host Range of Lytic Staphylophages on Clinical Isolates of Methicillin-Resistant Staphylococcus aureus

2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Mahtab Sadat Madani Boroujeni ◽  
Mohammadreza Mahzounieh ◽  
Azizollah Ebrahimi Kahrizsangi ◽  
Soudabeh Rostami ◽  
Azam Mokhtari ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bacterial Infections ◽  
Methicillin Resistance ◽  
Meca Gene ◽  
Plaque Assay ◽  
Clinical Isolates ◽  
Teaching Hospitals ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Methicillin Resistant

Background: Staphylococcus aureus (S. aureus) is a major cause of nosocomial infections in humans and animals. Because of the widespread resistance to antibiotics, microbiologists are trying to find other therapeutic interventions such as phage therapy for bacterial infections. Objectives: The present study aimed to isolate staphylophages with lytic effects on methicillin-resistant S. aureus (MRSA) clinical isolates as a potential alternative agent to antibiotic therapy. Methods: This experimental, descriptive study is performed in the Microbiology Laboratory of Shahrekord University (Iran) from September 2018 to March 2019. Two cocktails of staphylophages were isolated from Isfahan (Iran) urban sewage samples. The double-layer agar method was used to detect lytic phages. Morphology characteristic by transmission electron microscopy (TEM) images was used to identify staphylophages. One hundred and thirty three S. aureus were isolated from clinical samples of two teaching hospitals in Isfahan and Shiraz, Iran. Methicillin resistance and the presence of the mecA gene were determined by the disk diffusion method and polymerase chain reaction (PCR) assay, respectively. The phage susceptibility of mecA positive isolates was determined by plaque assay. Results: Two staphylophage cocktails were prepared, which had lytic effects on forty-four MRSA isolates. Cocktails 1 and 2 lysed 19 (14.2%) and 25 (18.7%) isolates, respectively. Of 133 S. aureus isolates, 88.7% carried the mecA gene. Conclusions: Different bacteriophages in two phage cocktails had relatively good lytic effects on S. aureus clinical isolates. Therefore, phage cocktails may be an appropriate alternative to antibiotics against S. aureus.

scholarly journals Characteristics of Staphylococcus aureus Isolated From Clinical Specimens in a Tertiary Care Hospital, Kathmandu, Nepal

2020 ◽  
Vol 13 ◽  
pp. 117863612097269
Author(s):  
Shesh Narayan Kandel ◽  
Nabaraj Adhikari ◽  
Binod Dhungel ◽  
Upendra Thapa Shrestha ◽  
Khadga Bikram Angbuhang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
Tertiary Care ◽  
Meca Gene ◽  
Significant Proportion ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Care Hospital ◽  
Clinical Specimens ◽  
Culture Positive

Introduction: Methicillin resistant Staphylococcus aureus (MRSA) is a major human pathogen associated with nosocomial and community infections. mecA gene is considered one of the important virulence factors of S. aureus responsible for acquiring resistance against methicillin. The main objective of this study was to explore the prevalence, antibiotic susceptibility pattern, and mec A gene. Methods: A total of 39 isolates of S. aureus were isolated from 954 clinical specimens processed in Microbiology laboratory of Himal Hospital, Kathmandu. Antimicrobial susceptibility test (AST) was performed by Kirby-Bauer disc diffusion method using cefoxitin, and performed Polymerase Chain Reaction (PCR) for amplification of mecA gene in MRSA isolates. Results: Out of 954 clinical samples, (16.2%; 153/954) samples had bacterial growth. Among 153 culture positive isolates, 25.5% (39/153) were positive for S. aureus. Among 39 S. aureus (61.5%; 24/39) were multiple drug resistant (MDR). On AST, amoxicillin was detected as the least effective while vancomycin was the most effective. The prevalence of methicillin resistance was 46% (18/39) of which 72.2% (13/18) were positive for mecA gene in PCR assay. Conclusion: One in 4 culture positive isolates from the clinical specimens were S. aureus, of which almost two-thirds were MDR. Around half of the MDR showed MRSA and significant proportion of them were positive for mecA gene. This study concludes that the mecA gene is solely dependent for methicillin resistance in S. aureus but the presence of gene is not obligatory. PCR detection of the mecA gene is reliable, valid and can be suggested for the routine use in diagnostic laboratories.

scholarly journals Resistance pattern of methicillin resistant Staphylococcus aureus among nasal isolates of HIV infected patients in a tertiary care hospital

2019 ◽  
Vol 7 (2) ◽  
pp. 428
Author(s):  
Manish Kumar Diwakar ◽  
Ankur Goyal ◽  
Sapna Goyal
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
Tertiary Care ◽  
Meca Gene ◽  
Nasal Carriage ◽  
Control Group ◽  
Care Hospital ◽  
Disc Diffusion ◽  
Increased Risk ◽  
Nasal Swab Sample

Background: Patients infected with HIV have an increased risk of nasal Staphylococcus aureus carriage as well as consecutive staphylococcal infections and is a major reservoir for MRSA which is potential risk factors for community acquired MRSA. Knowing the Nasal carriage status of Staphylococcus aureus and their Antibiogram will be beneficial for effective management of these patients.Methods: Nasal swab sample were collected from all the participants and processed for culture and identification of Staphylococcus aureus and their antimicrobial sensitivity. All the Staphylococcus aureus isolates were tested for Methicillin resistance by Oxacillin screen agar test, cefoxitin disc diffusion test and further confirmed by mecA gene PCR.Results: In this study out of 220 HIV seropositive patients, 43.64% isolates were confirmed to be S. aureus, 18.75% MRSA and 81.25% were MSSA. Cefoxitin disc diffusion showed 100% specificity (95% CI; 97.05%-100.00%), 100% sensitivity (95% CI; 83.89-100.00%) and 100% accuracy (95% CI; 97.47% to 100.00%) while comparing with gold standard mecA gene PCR. Among the nasal carriers; males (60%) ware dominant on females (40%). 31-50 years age group was strongly associated with MRSA nasal carriage. None of the isolates were resistant against lenozolid, teicoplanin and vancomycin while ampicillin (75%), ciprofloxacin (62.5%), clindamycin (59.38%) and cotrimoxazole (53.13%) showed increased resistance against S. aureus nasal carriage.Conclusions: Resistance among HIV positive persons for all antibiotics showed statistically significant while compared to control group. Cefoxitin disc diffusion can be used as surrogate agent for mecA gene detection.

scholarly journals Staphylococcus aureus with inducible clindamycin resistance and methicillin resistance in a tertiary hospital in Nepal

2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Devi Thapa ◽  
Susil Pyakurel ◽  
Sabita Thapa ◽  
Suresh Lamsal ◽  
Mahesh Chaudhari ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Susceptibility ◽  
Susceptibility Testing ◽  
Methicillin Resistance ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Care Hospital ◽  
Antibiotic Susceptibility Testing ◽  
Methicillin Resistant ◽  
Inducible Clindamycin Resistance

Abstract Background Staphylococcus aureus is a global public health issue in both community and hospital settings. Management of methicillin-resistant S. aureus (MRSA) infections are tough owing to its resistance to many antibiotics. Macrolide-lincosamide-streptogramin B (MLSB) antibiotics are commonly used for the management of MRSA. This study was aimed to determine the occurrence of inducible clindamycin- and methicillin-resistant S. aureus at a tertiary care hospital in Kathmandu, Nepal. Methods A total of 1027 clinical samples were processed following standard laboratory procedures and antibiotic susceptibility testing of S. aureus was performed by disc diffusion method. MRSA isolates were detected phenotypically using cefoxitin disc, and inducible clindamycin resistance was detected phenotypically using the D-zone test. Results Of 1027 samples, 321 (31.2%) were culture positive, of which 38 (11.8%) were S. aureus. All S. aureus isolates were susceptible to vancomycin, and 25 (67%) of S. aureus isolates were multidrug-resistant. Similarly, 15 (39.5%) of S. aureus were MRSA and 14 (36.5%) were inducible clindamycin-resistant phenotypes. Conclusion Inducible clindamycin and methicillin resistance were common in S. aureus. This emphasizes that the methicillin resistance test and the D-zone test should be incorporated into the routine antibiotic susceptibility testing in hospital settings.

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.

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