Phenotypic Expression of Methicillin Resistance in Staphylococcus Aureus

Abstract Background: Asymptomatic carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) can predispose the host to a wide array of infections that can be difficult to treat due to antibiotic resistance. To inform public health strategies, the study sought to describe MRSA nasal carriage frequencies and the associated factors concerning nasal carriage among patients attending Mbale Regional Referral Hospital (MRRH). Methods: Nasal swabs were obtained from consented (aged >15years) participants presenting to the hospital for medical care between January and April 2018[L1] . Direct Culture of swabs was performed on blood agar and then incubated at 37℃ for 24 hours. Identification of S. aureus was done using conventional biochemical tests. Phenotypic screening and confirmation of MRSA was done using cefoxitin disc (30µg) test and MICs on the Phoenix M50 instrument respectively. Patient demographic characteristics and the MRSA nasal carriage risk factors were collected using a pre-tested questionnaire. Results: Overall, majority of the participants were in-patients (138, 63.3%) with the proportions of both females and males among the participants being 154/218 (70.6%) and 64/218 (29.3%) respectively. Mean age for both female and male participants was 40.16 (SD± 17.04) years respectively. S. aureus nasal carriage rate among the participants was 22.9% (50/218), with 57.9% (29/50) of the harboured strains phenotypically expressing methicillin resistance (mecA mediated). Phenotypic co-expression with inducible clindamycin resistance and vancomycin resistance was displayed in 45.5% (23/50) and 2% (1/50) of the studied isolates respectively. Colonisation with MRSA did not show any significant relationship with all the studied factors. Conclusion: There was a moderate S. aureus nasal carriage among the participants in Mbale Regional Referral Hospital with a highly noted phenotypic expression of methicillin resistance among the isolated S. aureus strains. The studied factors were not significantly associated with the rate of MRSA nasal carriage. For surveillance purposes to combat future outbreaks, there is a need to do a larger study to better draw generalizable conclusions of carriage in the population. [L1]This is an important statement. I suggest that we reinstatate it if we are still in recommended word count

Download Full-text

Methicillin Resistant Staphylococcus aureus nasal carriage and associated factors in a rural tertiary hospital in Eastern Uganda: A prospective cross-sectional study

10.21203/rs.2.13651/v3 ◽

2020 ◽

Author(s):

Nobert Thembo ◽

George Masifa ◽

Gerald Kamugisha ◽

Robinah Nabitaka ◽

Benjamin Akais ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Associated Factors ◽

Methicillin Resistant Staphylococcus Aureus ◽

Methicillin Resistance ◽

Phenotypic Expression ◽

Nasal Carriage ◽

Referral Hospital ◽

Carriage Rate ◽

Regional Referral Hospital ◽

Methicillin Resistant

Abstract Background: Asymptomatic carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) can predispose the host to a wide array of infections that can be difficult to treat due to antibiotic resistance. To inform public health strategies, the study sought to describe MRSA nasal carriage frequencies and the associated factors concerning nasal carriage among patients attending Mbale Regional Referral Hospital (MRRH). Methods: Nasal swabs were obtained from consented (aged >15years) participants presenting to the hospital for medical care between January and April 2018 [L1] . Direct Culture of swabs was performed on blood agar and then incubated at 37℃ for 24 hours. Identification of S. aureus was done using conventional biochemical tests. Phenotypic screening and confirmation of MRSA was done using cefoxitin disc (30µg) test and MICs on the Phoenix M50 instrument respectively. Patient demographic characteristics and the MRSA nasal carriage risk factors were collected using a pre-tested questionnaire. Results: Overall, majority of the participants were in-patients (138, 63.3%) with the proportions of both females and males among the participants being 154/218 (70.6%) and 64/218 (29.3%) respectively. Mean age for both female and male participants was 40.16 (SD± 17.04) years respectively. S . aureus nasal carriage rate among the participants was 22.9% (50/218), with 57.9% (29/50) of the harboured strains phenotypically expressing methicillin resistance ( mecA mediated). Phenotypic co-expression with i nducible clindamycin resistance and vancomycin resistance was displayed in 45.5% (23/50) and 2% (1/50) of the studied isolates respectively. Colonisation with MRSA did not show any significant relationship with all the studied factors. Conclusion : There was a moderate S. aureus nasal carriage among the participants in Mbale Regional Referral Hospital with a highly noted phenotypic expression of methicillin resistance among the isolated S. aureus strains. The studied factors were not significantly associated with the rate of MRSA nasal carriage. For surveillance purposes to combat future outbreaks, there is a need to do a larger study to better draw generalizable conclusions of carriage in the population. [L1] This is an important statement. I suggest that we reinstatate it if we are still in recommended word count

Download Full-text

Methicillin Resistant Staphylococcus aureus nasal carriage and associated factors in a rural tertiary hospital in Eastern Uganda: A prospective cross-sectional study

10.21203/rs.2.13651/v1 ◽

2019 ◽

Author(s):

Nobert Thembo ◽

George Masifa ◽

Gerald Kamugisha ◽

Robinah Nabitaka ◽

Benjamin Akais ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Associated Factors ◽

Methicillin Resistant Staphylococcus Aureus ◽

Clinical Laboratory ◽

Methicillin Resistance ◽

Phenotypic Expression ◽

Nasal Carriage ◽

Referral Hospital ◽

Regional Referral Hospital ◽

Methicillin Resistant

Abstract Background: Asymptomatic carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) can predispose the host to a wide array of infections that would pose a challenge in the management of the cases in a current era encompassed with antibiotic resistance. To inform public health strategies, the study sought to describe MRSA nasal carriage frequencies and the associated factors concerning nasal carriage among patients attending Mbale Regional Referral Hospital (MRRH). Methods: Two hundred eighteen consented participants presenting to the hospital for medical care between January and April 2018 were recruited to participate in this study. Sampling was done on both anterior nares using a pre-moistened swab and then transported to the laboratory at Room temperature for the detection of MRSA. Culture was performed on blood agar and plates incubated at 37℃ for 24 hours. Identification of Staphylococcus aureus was done using conventional biochemical tests . MRSA was detected phenotypically using cefoxitin (30µg) as a surrogate test as per the Clinical Laboratory Standard Institute guidelines 2017 version. Patient demographic characteristics and the MRSA nasal carriage factors were collected using a pre-tested questionnaire. The collected raw data was entered into excel and later imported into STATA software for analysis. Results: Overall, Majority of the participants were in-patients (138, 63.3%) with the proportions of both females and males among the participants being 154/218 (70.6%) and 64/218 (29.3%) respectively. Mean age for both female and male participants was 40.16 (SD± 17.04) years respectively. Staphylococcus aureus nasal carriage rate among the participants was 22.9% (50/218), with 72% (36/50) of the harboured strains phenotypically expressing methicillin resistance. Colonization with Methicillin Resistant Staphylococcus aureus did not show any significant relationship with all the studied factors. Conclusion: There was a moderate Staphylococcus aureus nasal carriage among the participants in Mbale Regional Referral Hospital. We also observed a highly displayed phenotypic expression of methicillin resistance among the isolated Staphylococcus aureus strains. The studied factors indicated an independent influence on the rate of nasal carriage. For surveillance purposes to combat future outbreaks, there is a need to do a larger study with better power to better draw generalizable conclusions of carriage in the population.

Download Full-text

Molecular Characterization of Methicillin Resistant and Extended Spectrum β-Lactamase Staphylococcus aureus Isolated from Burn Patients

Kurdistan Journal of Applied Research ◽

10.24017/science.2020.ichms2020.16 ◽

2020 ◽

pp. 145-151

Author(s):

Shawnm Ahmed Aziz

Keyword(s):

Staphylococcus Aureus ◽

Methicillin Resistance ◽

Vancomycin Resistance ◽

World Health ◽

Molecular Technique ◽

Burn Patients ◽

Beta Lactamase ◽

Beta Lactam ◽

Extended Spectrum Beta Lactamase ◽

Extended Spectrum

Antibiotic resistance has become a major world health challenge and has limited the ability of physician's treatment. Staphylococcus aureus the most notorious pathogens causes morbidity and mortality especially in burn patients. However, Staphylococcus aureus rapidly acquired resistance to multiple antibiotics. Vancomycin, a glycopeptide antibiotic remains a drug of choice for treatment of severe Methicillin Resistance S. aureus infections. This study aimed to detect the emergence of beta-lactam and glycopeptide resistance genes. 50 clinical specimens of S. aureus collected from burn patients in burn and plastic surgery units in Sulaimani-Iraq city. All specimens were confirmed to be positive for S. aureus. All the isolates were assessed for their susceptibility to different antibiotics depending on NCCL standards, followed by Extended Spectrum Beta Lactamase detection by double disk diffusion synergy test. The production of β- lactamases was evaluated in the isolated strains by several routine methods and polymerase chain reaction. Among the isolates 94% were Methicillin resistance and 34.28% were Extended Spectrum Beta Lactamase producer. PCR based molecular technique was done for the bla genes related to β- lactamase enzymes by the specific primers, as well as genes which related to reduced sensitivity to Vancomycin were detected. The results indicated that all isolated showed the PBP1, PBP2, PBP3, PBP4, trfA and trfB, graSR, vraS except the vraR gene and the prolonged therapy of Methicillin resistance infection with teicoplanin have been associated with progress of resistance and the rise of tecoplanin resistance may be a prologue to evolving Vancomycin resistance. In conclusion, beta-lactam over taking can rise Vancomycin- Intermediate S. aureus strains leading to appearance of Vancomycin resistance although the treatment of Vancomycin resistant infections is challenging.

Download Full-text