scholarly journals The Antibiotic Susceptibilities of Methicilline-Resistant Staphylococcus aureus Strains Isolated From Various Clinical Samples

2021 ◽  
Vol 8 (4) ◽  
pp. 266-270
Author(s):  
Erdal Özbek ◽  
Hakan Temiz ◽  
Nida Özcan ◽  
Hasan Akkoc

Objective: In this study, it was aimed to determine the in vitro susceptibilities of Methicillin-Resistant Staphylococcus aureus (MRSA) strains to fluoroquinolone, linezolid, tigecycline, and quinupristin/dalfopristin as well as the macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype. Materials and Methods: A total of 94 MRSA strains isolated from various clinical samples in our hospital laboratory between January 2020 and September 2020 were included. The in-vitro susceptibilities of MRSA strains against fluoroquinolone, linezolid, tigecycline, and quinupristin/dalfopristin were determined by Kirby-Bauer disc diffusion assay according to The European Committee on Antimicrobial Susceptibility Testing (EUCAST).  The E test assay was used for evaluation of tigecycline susceptibility. The D-zone test was performed with erythromycin (15 μg) and clindamycin (2 μg) discs to determine the MLSB resistance. Besides, bacterial identification, antibiotic susceptibility tests including methicillin resistance and MLSB phenotype determination were performed by using VITEK 2 Gram-positive diagnostic kits (Bio-Mérieux/France). Results: Results: Among 94 MRSA strains included, resistance rates to ciprofloxacin, moxifloxacin, tigecycline, and quinupristin/dalfopristin were found as 71% (67 isolates) 64% (60 isolates), 17% (16 isolates), and 2% (2 isolates), respectively. Resistance was not detected for linezolid. A total of 36 (49%) isolates showed cMLSB resistance phenotype, while 18(19%) had iMLSB resistance. The methicillin susceptibility (MS) phenotype – strains resistant to erythromycin and susceptible to clindamycin- was not detected. Conclusion: Very little resistance was found to linezolid, quinupristin/dalfopristin and tigecycline. Therefore, these antibiotics may be beneficial for the proper treatment of infections caused by MLSB-resistant isolates.

2021 ◽  
Author(s):  
Erdal Ozbek ◽  
Hakan TEMİZ ◽  
Nida ÖZCAN ◽  
Hasan AKKOÇ

Abstract Background and Objective:: In this study, it was aimed to determine the in vitro susceptibilities of Methicillin-Resistant Staphylococcus aureus (MRSA) strains to fluoroquinolone, linezolid, tigecycline, and quinupristin /dalfopristin as well as the macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype. Materials and Methods A total of 94 MRSA strains isolated from various clinical samples in our hospital laboratory between January 2020 and September 2020 were included. The in-vitro susceptibilities of MRSA strains against fluoroquinolone, linezolid, tigecycline, and quinupristin/dalfopristin were determined by Kirby-Bauer disc diffusion assay according to The European Committee on Antimicrobial Susceptibility Testing (EUCAST). The E test assay was used for evaluation of tigecycline susceptibility. The D-zone test was performed with erythromycin (15 µg) and clindamycin (2 µg) discs to determine the MLSB resistance. Besides, bacterial identification, antibiotic susceptibility tests including methicillin resistance and MLSB phenotype determination were performed by using VİTEK 2 Gram-positive diagnostic kits(Bio-Mérieux/France). Results Results: Among 94 MRSA strains included, resistance rates to ciprofloxacin, moxifloxacin, tigecycline, and quinupristin/dalfopristin were found as 71% (67 isolates) 64%(60 isolates), 17%(16 isolates), and 2% (2 isolates), respectively.. Resistance was not detected for linezolid. A total of 36(49%) isolates showed cMLSB resistance phenotype while 18(19%) had iMLSB resistance. The MS phenotype – strains resistant to erythromycin and susceptible to clindamycin- was not detected. Conclusion Very little or no resistance was found to linezolid, quinupristin/dalfopristin and tigecycline. Therefore, these antibiotics may be beneficial for the proper treatment of infections caused by MLSB-resistant isolates.


2018 ◽  
Vol 10 (1) ◽  
pp. 108-115
Author(s):  
Manjunath Chavadi ◽  
Rahul Narasanna ◽  
Ashajyothi Chavan ◽  
Ajay Kumar Oli ◽  
Chandrakanth Kelmani. R

Introduction:Methicillin-resistantStaphylococcus aureus(MRSA) is the major threat that is a result of the uncontrolled use of antibiotics causing a huge loss in health, so understanding their prevalence is necessary as a public health measure.Objective:The aim of this study was to determine the prevalence of methicillin-resistant MRSA and virulence determinant among associatedS. aureusfrom the clinical samples obtained from various hospital and health care centers of the Gulbarga region in India.Materials and Methods:All the collected samples were subjected for the screening ofS. aureusand were further characterized by conventional and molecular methods including their antibiotic profiling. Further, the response of methicillin antibiotic on cell morphology was studied using scanning electron microscopy.Results:A total 126S. aureuswas isolated from the clinical samples which showed, 100% resistant to penicillin, 55.5% to oxacillin, 75.3% to ampicillin, 70.6% to streptomycin, 66.6% to gentamicin, 8.7% to vancomycin and 6.3% to teicoplanin. The selected MRSA strains were found to possessmecA(gene coding for penicillin-binding protein 2A) andfemA(factor essential for methicillin resistance)genetic determinants in their genome with virulence determinants such as Coagulase (coa) and the X region of the protein A (spa)gene. Further, the methicillin response in resistantS. aureusshowed to be enlarged and malformed on cell morphology.Conclusion:The molecular typing of clinical isolates ofS. aureusin this study was highly virulent and also resistant to methicillin; this will assist health professionals to control, exploration of alternative medicines and new approaches to combat Staphylococcal infections more efficiently by using targeted therapy.


2003 ◽  
Vol 185 (18) ◽  
pp. 5465-5472 ◽  
Author(s):  
Yuki Katayama ◽  
Hong-Zhong Zhang ◽  
Dong Hong ◽  
Henry F. Chambers

ABSTRACT Although the staphylococcal methicillin resistance determinant, mecA, resides on a mobile genetic element, staphylococcus cassette chromosome mec (SCCmec), its distribution in nature is limited to as few as five clusters of related methicillin-resistant Staphylococcus aureus (MRSA) clones. To investigate the potential role of the host chromosome in clonal restriction of the methicillin resistance determinant, we constructed plasmid pYK20, carrying intact mecA, and introduced it into several methicillin-susceptible Staphylococcus aureus strains, five of which were naive hosts (i.e., mecA not previously resident on the host chromosome) and five of which were experienced hosts (i.e., methicillin-susceptible variants of MRSA strains from which SCCmec was excised). We next assessed the effect of the recipient background on the methicillin resistance phenotype by population analysis, by assaying the mecA expression of PBP2a by Western blot analysis, and by screening for mutations affecting mecA. Each experienced host transformed with pYK20 had a resistance phenotype and expressed PBP2a similar to that of the parent with chromosomal SCCmec, but naive hosts transformed with pYK20 selected against its expression, indicative of a host barrier. Either inducible β-lactamase regulatory genes blaR1-blaI or homologous regulatory genes mecR1-mecI, which control mecA expression, acted as compensatory elements, permitting the maintenance and expression of plasmid-carried mecA.


Author(s):  
Pradeep Kumar ◽  
Geeta Gupta ◽  
Gajendra Kumar Gupta ◽  
Vashishth Mishra ◽  
Gaurav Gupta

Background: Infections caused by Staphylococci are frequently linked to indwelling medical equipment. These are extremely difficult to treat with antibiotics. In India, the prevalence of Methicillin-Resistant Staphylococcus aureus (MRSA) varies from 30 to 70%, resulting in high mortality, increased economic burden, and high treatment failure in tertiary care hospitals. Rapid and reliable identification of MRSA is critical for infection management and avoiding the needless use of antibiotics. Materials and Methods: This prospective study was carried out in the Department of Microbiology, Santosh Medical College, Ghaziabad, from the 1st of August 2020 to the 31st of January 2021. MRSA isolates were screened and confirmed using standard methods recommended by the Clinical and Laboratory Standards Institute (CLSI). Methicillin resistance, in Staphylococcus aureus strains, was evaluated using oxacillin/cefoxitin. The Kirby-Bauer disc diffusion technique was used to assess the antibiotic susceptibility pattern of all MRSA strains. Results: In this investigation, MRSA was identified in 29.4% of the 384 Staphylococcus aureus strains. When compared to females, men outnumbered females. Cefoxitin detects a greater amount of MRSA than oxacillin. In this investigation, the majority of MRSA was found in pus samples. Conclusion: MRSA prevalence is known to vary depending on geographical region, hospital type, investigated population, and technique of detection used. Given the clinical implications of MRSA infection and its fast transmission capability, MRSA strains must be monitored on a regular basis.


Author(s):  
Fahimeh Nourbakhsh ◽  
Vajiheh Nourbakhsh ◽  
Samaneh Borooni ◽  
Elaheh Tajbakhsh ◽  
Dana Daneshmand

Background and Aims: Based on the results, Staphylococcus aureus is one of the serious infectious agents found in community and hospitals with remarkable potential for high morbidity and mortality around the globe. The present study was carried out for molecular investigation of methicillinresistant Staphylococcus aureus strains and Staphylococcal Chromosomal Cassette mec (SCCmec) phenotypes isolated from the intensive care unit in Hazrat Fatemeh Zahra hospital of Isfahan. Materials and Methods: A total of 76 clinical wound samples were collected from Hazrat Fatemeh Zahra Hospital in Isfahan and evaluated by polymerase chain reaction (PCR) methods. The Methicillin resistance Staphylococcus aureus (MRSA) screening was performed by genotypic and phenotypic methods; also antibiotic resistance pattern was determined by using the disk diffusion method and related genes by PCR. Results: Totally, 53 (69.7%) out of 76 clinical samples were positive for MRSA. Of the 76 MRSA strains, 39 (63.51%) were PVL positive (51.3%). The most commonly infected samples were collected from wounds (40.8%). The most commonly detected antibiotic resistance genes were mecA (89.61%), tetK (88.23%), tetM (49.15%) and msrA (46.93%). Resultantly, it was shown that MRSA has the highest level of resistance against methicillin (98%), penicillin (97.24%), tetracycline (89.64%). It was also revealed that the most commonly detected SCCmec types in the MRSA strains are types II (14.53%) and III (16.82%). Conclusions: In summary, this paper argues that the orderly surveillance of hospital-associated infections and initial management and supervision of the antibiotic resistance patterns are required to control the prevalence of MRSA.


2014 ◽  
Vol 52 (196) ◽  
pp. 977-981 ◽  
Author(s):  
Prakash Chandra Pahadi ◽  
Upendra Thapa Shrestha ◽  
Nabaraj Adhikari ◽  
Pradeep Kumar Shah ◽  
Ritu Amatya

Introduction: Methicillin resistant Staphylococcus aureus (MRSA), majorly associated with nosocomial and community infections worldwide, are emerging as resistant strains to many antibiotics narrowing down the efficacy of antimicrobial therapy. In order to investigate the changing resistant pattern of MRSA to empirical drugs, the study was carried out at KIST Medical College and Hospital, Nepal. It also aims to determine the minimum inhibitory concentration of vancomycin among MRSA. Methods: Altogether 3500 clinical samples including 1303 blood, 1489 urine and 708 body fluids were collected and processed. Isolated S. aureus were further screened for methicillin resistance by Kirby-Bauer disk diffusion technique using cefoxitin (30μg) disk. All MRSA were subjected to in vitro determination of MIC of vancomycin by agar dilution method as recommended by CLSI guidelines. Results: Total 287 S. aureus were isolated from the different clinical samples. Altogether 248 (86.41%) were found to be multidrug resistance (MDR) while 42 (14.63%) of the isolates were methicillin resistance with the highest prevalence in the age group of 16-30. All 42 (100%) MRSA isolates were resistant to ampicillin and penicillin followed by 41 (97.62%), 32 (76.19%), 31(73.81%), 29 (69.05%), 9 (21.43%) and seven (16.67%) to cefotaxime, gentamycin, cotrimoxazole, erythromycin, tetracycline and ciprofloxacin respectively. Although all MRSA strains were sensitive to vancomycin on disc diffusion, four isolates were intermediates in vitro determination of MIC of vancomycin. The break point for vancomycin was found to be 15mm. Conclusions: The increment in vancomycin MIC among MRSA is alarming. Strict control measures to prevent MRSA spread and a routine surveillance for VRSA must be incorporated in hospitals.  Keywords: mdr; mrsa; mic; visa; vrsa.


2012 ◽  
Vol 57 (1) ◽  
pp. 83-95 ◽  
Author(s):  
Susan Boyle-Vavra ◽  
Shouhui Yin ◽  
Dae Sun Jo ◽  
Christopher P. Montgomery ◽  
Robert S. Daum

ABSTRACTStaphylococcus aureusinfections caused by strains that are resistant to all forms of penicillin, so-called methicillin-resistantS. aureus(MRSA) strains, have become common. One strategy to counter MRSA infections is to use compounds that resensitize MRSA to methicillin.S. aureusresponds to diverse classes of cell wall-inhibitory antibiotics, like methicillin, using the two-component regulatory system VraSR (vra) to up- or downregulate a set of genes (the cell wall stimulon) that presumably facilitates resistance to these antibiotics. Accordingly, VraS and VraR mutations decrease resistance to methicillin, vancomycin, and daptomycin cell wall antimicrobials.vraSandvraRare encoded together on a transcript downstream of two other genes, which we callvraUandvraT(previously calledyvqF). By producing nonpolar deletions invraUandvraTin a USA300 MRSA clinical isolate, we demonstrate thatvraTis essential for optimal expression of methicillin resistancein vitro, whereasvraUis not required for this phenotype. The deletion ofvraTalso improved the outcomes of oxacillin therapy in mouse models of lung and skin infection. SincevraTexpressed intransdid not complement avraoperon deletion, we conclude that VraT does not inactivate the antimicrobial. Genome-wide transcriptional microarray experiments reveal that VraT facilitates resistance by playing a necessary regulatory role in the VraSR-mediated cell wall stimulon. Our data prove that VraTSR comprise a novel three-component regulatory system required to facilitate resistance to cell wall agents inS. aureus. We also provide the firstin vivoproof of principle for using VraT as a sole target to resensitize MRSA to β-lactams.


2021 ◽  
Author(s):  
Hilal Basak Erol ◽  
Banu Kaskatepe ◽  
Zekiye Bakkaloglu ◽  
Serap Suzuk Yildiz

Abstract Infections due to methicillin-resistant Staphylococcus aureus (MRSA) are a growing concern for public health resulting in increase in morbidity, length of hospital stay, and cost of treatment. MRSA nasal-swab screening may give clinicians additional information for decision of empiric antimicrobial agents. While increasing antibiotic resistance leads to new treatment approaches, bacteriophages are one of the most promising methods for these alternatives. It was aimed to determine the effectiveness of bacteriophages against MRSA isolates. Nasal swab samples were collected from outpatients without any evidence of infection who applied to Hatay, Mersin and Gaziantep family and immigration health centers. A series (35) were isolate from Turkish patients, G series (64) were isolated from Syrian immigrants. Methicillin resistance were determined by phenotypically and genotypically. Also, antibiotic susceptibilities of all isolates were determined against erythromycin, clindamycin, gentamicin, linezolid, rifampicin, and mupirosin. The total antimicrobial resistance rates of isolates were found 11%, 28%, 8%, 5%, 16%, 19%, and 29% respectively. The high susceptibility rate against ciprofloxacin (88.8%) was remarkable. The overall susceptibility of MRSA strains to ENKO, INTESTI, PYO, SES, and STAPHYLOCOCCAL bacteriophages was 67.7%, 55.5%, 53.5%, 61.6% and 44.4%, respectively. The antibiotic susceptibility rates (except erythromycin), and efficacy of bacteriophages were higher in group A. Considering that high efficacy rates were not achieved in the study and the sensitivity rates of Turkish isolates to all phages were found higher than Syrian isolates, searching for phages in the geography where the pathogen is common, may be helpful to obtain suitable phages for treatment.


2016 ◽  
Vol 2016 ◽  
pp. 1-4 ◽  
Author(s):  
Cennet Rağbetli ◽  
Mehmet Parlak ◽  
Yasemin Bayram ◽  
Huseyin Guducuoglu ◽  
Nesrin Ceylan

Objective. Recently, community and hospital-acquired infections withStaphylococcus aureushave increased and raised antibiotic resistant isolates. In this study, we aimed to evaluate the antibiotic resistance profile ofS. aureusisolates over several years in various clinical specimens from our hospital.Materials and Methods.S. aureusstrains from 2009 to 2014 were isolated from various clinical samples at Yuzuncu Yil University, Dursun Odabas Medical Center, Microbiology Laboratory, and their antibiotic susceptibility test results were retrospectively investigated. The isolates were identified by conventional methods, and antibiotic susceptibility tests were performed by the Phoenix (Becton Dickinson, USA) automated system method according to Clinical and Laboratory Standards Institute (CLSI) standards.Results. A total of 1,116S. aureusisolates were produced and methicillin-resistantS. aureus(MRSA) to 21% of allS. aureusisolates between 2009 and 2014. According to the results of susceptibility tests of all isolates ofS. aureus, they have been identified as sensitive to vancomycin, daptomycin, linezolid, and levofloxacin. While the resistance rates to nitrofurantoin, quinupristin-dalfopristin, and trimethoprim-sulfamethoxazole were determined as 0.3%, 2.4%, and 6%, respectively, resistance rates to penicillin, erythromycin, rifampicin, gentamicin, and clindamycin were determined as 100%, 18%, 14%, 14%, and 11%, respectively. The highest percentage of methicillin resistance was determined as 30% in 2009, and the resistance was determined to have decreased in subsequent years (20%, 16%, 13%, 19%, and 21%) (p<0.001).Conclusion. Currently, retrospective evaluations of causes of nosocomial infection should be done periodically. We think that any alteration of resistance over the years has to be identified, and all centers must determine their own resistance profiles, in order to guide empirical therapies. Reducing the rate of antibiotic resistance will contribute to reducing the cost of treatment.


2020 ◽  
pp. 28-30
Author(s):  
Neha Jha ◽  
R. S. Prasad ◽  
P. N. Jha ◽  
Debarshi Jana

Background: Methicillin Resistant Staphylococcus aureus (MRSA) prevalence is increasing worldwide and it remains as a major cause of morbidity and mortality in hospitalised patients due to its versatile behaviour towards antibiotics. Aims: This study was done to find out the prevalence and antimicrobial susceptibility pattern of MRSA isolates at our hospital setup, in order to guide policy on the appropriate use of antibiotics. Settings and Design: The study was a prospective observational study, carried out in the Department of Microbiology, Darbhanga Medical College, Laheriasarai, Bihar. Methods and Material: A total number of 288 strains of Staphylococcus aureus were isolated from various clinical samples received in the laboratory. Staphylococcus aureus was identified by routine standard operative procedures. Antimicrobial susceptibility testing was done by Kirby-Bauer disc diffusion method and the results were interpreted following Clinical Laboratory Standards Institute (CLSI) guidelines. Methicillin resistance was screened by using oxacillin disks [1 mcg]. Statistical analysis used: Data obtained was analysed and presented in counts and percentages. 95 % confidence interval values were also calculated. Results: Methicillin resistance was documented in 120 [41.6%] Staphylococcus aureus isolates. Most of them were isolated from pus, wound swabs, urine and respiratory samples. All MRSA isolates were resistant to penicillin and cefepime. The resist-ance was high to tetracycline, erythromycin, co-trimoxazolepiperacillin / tazobactam, and ciprofloxacin; moderate to amino-glycosides, clindamycin, chloramphenicol and levofloxacin. All MRSA strains were susceptible to vancomycin. Overall, 63.3% [76/120] of MRSA strains were found to be resistant to more than 6 antimicrobials tested. Conclusions: Our study emphasizes the need for regular surveillance and formulation of a strict drug policy on the appropriate use of antibiotics to control MRSA infections. This would also minimise the irrational use of vancomycin and the emergence of vancomycin resistant Staphylococcus aureus [VRSA].


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