Genomic Overview into the Evolving Epidemiology of Methicillin-Resistant Staphylococcus aureus

2020 ◽  
Vol 21 (3) ◽  
pp. 125-131
Author(s):  
Yara El dessouky ◽  
Shaimaa Mouftah ◽  
Mohamed Elhadidy
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Human Infection ◽  
Emerging Infections ◽  
Beta Lactam ◽  
Methicillin Resistant ◽  
Gram Positive Bacteria ◽  
Beta Lactam Antibiotics ◽  
Mrsa Strains ◽  
Hospital Acquired

Emerging infections represent an enormous challenge to both human and veterinary medicine. Identification of Methicillin-Resistant Staphylococcus aureus (MRSA) in various species and in food has raised concerns about the roles of animals in the epidemiology of MRSA. MRSA are a group of gram-positive bacteria, distinct from other strains of S. aureus in that this pathogen is resistant to methicillin, oxacillin, and all beta-lactam antibiotics. The severity of infections caused by MRSA depends on the strain responsible for the infection and can vary from soft tissue infections to bacteremia and sometimes pneumonia. MRSA strains are divided into clones, based on their genetic makeup. According to the setting of infection, MRSA are divided into three epidemiological types: hospital acquired (HA-MRSA), community acquired (CA-MRSA), and livestock acquired (LA-MRSA) (ie. Transmitted from animal carriers). The epidemiology of HA-MRSA, CA-MRSA, and LA-MRSA is blurred as different recent genetic studies have revealed significant overlap of identical clones between HA-MRSA and CA-MRSA, and the significant increase of human infection caused by LA-MRSA. Furthermore, the animal-human and animal-animal transmission of LA-MRSA has prompted further investigation to study the origin of this epidemiological type and the transmission dynamics. The genetic and virulence profiles of different types of MRSA vary widely, where community acquired and livestock acquired strains are more virulent than hospital acquired strains. This review sheds light on three epidemiological groups of MRSA (HA-MRSA, CA-MRSA, and LA-MRSA), and their most prevalent clonal clusters, that can consequently allow better understanding of their evolution, emergence, transmission, and global dissemination.

scholarly journals Methicillin Resistant Staphylococcus aureus: Prevalence And Antibiogram In A Tertiary Care Hospital in Western Nepal

2009 ◽  
Vol 3 (09) ◽  
pp. 681-684 ◽  
Author(s):  
Hare Krishna Tiwari ◽  
Ayan Kumar Das ◽  
Darshan Sapkota ◽  
Kunjukunju Sivrajan ◽  
Vijay Kumar Pahwa
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Inhibitory Concentration ◽  
Tertiary Care ◽  
Care Hospital ◽  
Methicillin Resistant ◽  
Mrsa Strains ◽  
Susceptibility Tests ◽  
Rational Use Of Antibiotics ◽  
Hospital Acquired

Background: Methicillin resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial and community infections. Its prevalence varies with country and with hospitals within a country. The current study estimates the prevalence of MRSA strains and investigates their antibiogram in western Nepal. Methodology: A total of 162 S. aureus strains were isolated from various clinical specimens, and antibiotic susceptibility tests were performed using disc diffusion, growth on oxacillin screen agar, and oxacillin minimum inhibitory concentration (MIC). Results: One hundred and twelve (69.1%) strains were found to be MRSA, of which 37 (33.1%) were community acquired and 75 (66.9%) were hospital acquired. Of 112 MRSA strains, 45 (40.1%) were multi-drug resistant. All MRSA strains were found resistant to penicillin, and 91.9%, 87.4%, 77%, and 55.5% were resistant to amoxicillin, ampicillin, trimethoprim/sulfamethoxazole, and cephalexin, respectively. However, low resistance was observed with amikacin (19%), ciprofloxacin (26.5%), and norfloxacin (30.6%). All strains were sensitive to vancomycin. Conclusion: The reported rate of MRSA prevalence is alarming. Given the ability of MRSA to spread from person to person, it is necessary to adhere to rational use of antibiotics and to raise awareness among the concerned communities and tourists who visit this area.

scholarly journals Full-Genome Sequencing Identifies in the Genetic Background Several Determinants That Modulate the Resistance Phenotype in Methicillin-Resistant Staphylococcus aureus Strains Carrying the Novel mecC Gene

2017 ◽  
Vol 61 (3) ◽  
Author(s):  
Catarina Milheiriço ◽  
Hermínia de Lencastre ◽  
Alexander Tomasz
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Resistance ◽  
Genetic Background ◽  
Beta Lactam ◽  
Methicillin Resistant ◽  
Content Type ◽  
Resistance Phenotype ◽  
Beta Lactam Antibiotics ◽  
Oxacillin Resistance ◽  
Mrsa Strains

ABSTRACT Most methicillin-resistant Staphylococcus aureus (MRSA) strains are resistant to beta-lactam antibiotics due to the presence of the mecA gene, encoding an extra penicillin-binding protein (PBP2A) that has low affinity for virtually all beta-lactam antibiotics. Recently, a new resistance determinant—the mecC gene—was identified in S. aureus isolates recovered from humans and dairy cattle. Although having typically low MICs to beta-lactam antibiotics, MRSA strains with the mecC determinant are also capable of expressing high levels of oxacillin resistance when in an optimal genetic background. In order to test the impact of extensive beta-lactam selection on the emergence of mecC-carrying strains with high levels of antibiotic resistance, we exposed the prototype mecC-carrying MRSA strain, LGA251, to increasing concentrations of oxacillin. LGA251 was able to rapidly adapt to high concentrations of oxacillin in growth medium. In such laboratory mutants with increased levels of oxacillin resistance, we identified mutations in genes with no relationship to the mecC regulatory system, indicating that the genetic background plays an important role in the establishment of the levels of oxacillin resistance. Our data also indicate that the stringent stress response plays a critical role in the beta-lactam antibiotic resistance phenotype of MRSA strains carrying the mecC determinant.

scholarly journals Rates of Carriage of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in an Outpatient Population

2003 ◽  
Vol 24 (6) ◽  
pp. 439-444 ◽  
Author(s):  
Julie Kenner ◽  
Tasha O'Connor ◽  
Nicholas Piantanida ◽  
Joel Fishbain ◽  
Bardwell Eberly ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Risk Factor ◽  
Clinical Risk Factor ◽  
Beta Lactam ◽  
Methicillin Resistant ◽  
Beta Lactam Antibiotics ◽  
Time Period ◽  
Clinical Illness ◽  
Mrsa Strains ◽  
Mrsa Colonization

AbstractObjectives:To assess the prevalence of and the clinical features associated with asymptomatic Staphylococcus aureus colonization in a healthy outpatient population, and to compare the characteristics of colonizing methicillin-resistant S. aureus (MRSA) strains with those of strains causing infection in our community and hospital.Setting:Outpatient military clinics.Methods:Specimens were obtained from the nares, pharynx, and axillae of 404 outpatients, and a questionnaire was administered to obtain demographic and risk factor information. MRSA strains were typed by pulsed-field gel electrophoresis (PFGE) and evaluated for antibiotic susceptibility. Antibiograms of study MRSA strains were compared with those of MRSA strains causing clinical illness during the same time period.Results:Methicillin-susceptible S. aureus (MSSA) colonization was present in 153 (38%) of the 404 asymptomatic outpatients, and MRSA colonization was present in 8 (2%). Detection of colonization was highest from the nares. No clinical risk factor was significantly associated with MRSA colonization; however, a tendency was noted for MRSA to be more common in men and in those who were older or who had been recently hospitalized. All colonizing MRSA strains had unique patterns on PFGE. In contrast to strains responsible for hospital infections, most colonizing isolates of MRSA were susceptible to oral antibiotics.Conclusions:MRSA and MSSA colonization is common in our outpatient population. Colonization is best detected by nares cultures and most carriers of MRSA are without apparent predisposing risk factors for acquisition. Colonizing isolates of MRSA are heterogeneous and, unlike nosocomial isolates, often retain susceptibility to other non-beta-lactam antibiotics.

Community-Acquired Methicillin-Resistant Staphylococcus Aureus Infections in Otolaryngology

1992 ◽  
Vol 107 (3) ◽  
pp. 434-437 ◽  
Author(s):  
Ron D. Gottlieb ◽  
Mahendra K. Shah ◽  
David C. Perlman ◽  
Charles P. Kimmelman
Keyword(s):  
Staphylococcus Aureus ◽  
Antibiotic Therapy ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Intravenous Drug ◽  
Intravenous Drug Use ◽  
Methicillin Resistant ◽  
Mrsa Strains ◽  
Hospital Acquired ◽  
Susceptibility And Resistance ◽  
Multiple Antibiotics

Soon after the introduction of methicillin, strains of Staphylococcus aureus resistant to methicillin were reported. Methicillin-resistant Staphylococcus aureus (MRSA) has become a common hospital pathogen, often resistant to multiple antibiotics, while causing significant morbidity and mortality. Community-acquired MRSA infections have been infrequently documented. Most reports have been associated with intravenous drug abuse. This report reviews 15 patients with community-acquired MRSA infections of the head and neck. None admitted to intravenous drug use. Additionally, no patient was known to be a healthcare worker. The MRSA strains showed antibiotic susceptibility and resistance profiles different from typical hospital-acquired MRSA isolates. All but one infection resolved with adequate surgical or appropriate antibiotic therapy. Clinicians should become aware of the possibility of community-acquired MRSA in the patient who has had continued infection despite antibiotic therapy.

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