PREVALENCE AND ANTIMICROBIAL RESISTANCE PATTERN OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS ISOLATED FROM DIFFERENT CLINICAL SAMPLES

Received: 15 January 2017 Final Accepted: 15 February 2017 Published: March 2017 Background: Methicillin Resistant Staphylococcus aureus (MRSA) since its emergence, has been a challenge for the community owing to its potential to cause life threatening events like sepsis, endocarditis and osteomyelitis. Aims and objectives: To investigate the prevalence of MRSA in various clinical samples and to find the antibiotic resistance pattern of the MRSA isolates. Materials and Methods: Oxacillin resistance screening agar with 5.5% Nacl and Kirby–Bauer disk diffusion method (cefoxitin 30μg disk) were used for MRSA confirmation and antibiotic resistance testing was done as per CLSI 2016 guidelines. E-test was done for testing sensitivity to Vancomycin. Result: Staphylococcus aureus was isolated from 350 specimens. Out of these 350 isolates, 220 (62.86%) were methicillin sensitive and rest 130 (37.14%) isolates were MRSA. Most of the MRSA isolates were from urine samples (43.71%) followed by pus (24.0%), and putum (11.14%). MRSA isolates showed high resistance to ciprofloxacin (53.38%), and clindamycin (42.31%). linezolid resistance was seen in only 6.15% and all isolates were sensitive to vancomycin. Conclusion: A high prevalence of MRSA (37.14%.) in our institution warrants the judicious use of antibiotics in treating infections caused by Staphylococcus aureus. Vancomycin and linezolid are good treatment options in infections caused by MRSA isolates.


ISSN: 2320-5407
Int. J. Adv. Res. 5(3), 2195-2201 2196 England, and since then it continues to be the most dreadful strains of S. aureus. It is one of the most common pathogens that cause nosocomial infections 6,7 In India, a multicentric trial conducted between January 2008 to December 2009 at several healthcare centres 8 found MRSA prevalence among specimen collected from outpatients, ward inpatients and ICU to be 28, 42 and 43 per cent, respectively in 2008 and 27, 49 and 47 per cent, respectively in 2009, thus indicating that MRSA has assumed a concerning proportion. Moreover, they stressed on the pattern of changing antibiotic susceptibility and also recommended robust antimicrobial stewardship and strengthened infection control measures to prevent spread and reduce emergence of resistance.
It must be kept in mind that current therapeutic options for MRSA are limited few expensive drugs like vancomycin, linezolid, teicoplanin, daptomycin and streptogramins. Another alarming sign is that emergence of resistance to Vancomycin, although at a low level has been reported in literature 9 , thus underlining the observations made by the multicentric study cited above.
Hence, the present study was planned with an aim to assess the prevalence and antibiotic susceptibility of Methicillin resistant Staphylococcus aureus at Era's Lucknow Medical College and Hospital (ELMCH)

Aims and Objectives:-
The present study was carried out with an aim to evaluate the prevalence, antibiotic susceptibility of MRSA in a tertiary care centre. This aim was fulfilled with the help of following objectives:

Results:-
A total of 350 specimens from the patients were collected which were subjected to MRSA sensitivity. Out of 350 specimens, 220 (62.86%) were found to be MSSA and only 130 (37.14%) specimens were found to be MRSA. Prevalence of MRSA in our tertiary care centre was found to be 37.14.  Difference in type of specimens between MRSA and MSSA was found to be statistically significant (p<0.001). All MSSA specimen were sensitive against Cefoxitin. The resistance rate in decreasing order was Ciprofloxacin (28.6%), Clindamycin (21.4%), Doxycycline (7.7%), Norfloxacin (6.8%), Amikacin (5%) and Linezolid (3.6%). Vancomycin was sensitive against 100% of MRSA isolates.

Discussion:-
Methicilllin resistant Staphylococcus aureus since its emergence has been a challenge for the healthcare workers owing to its potential to cause life-threatening events like sepsis, endocarditis, and osteomyelitis. Major outbreaks of MRSA and its different phage types have also been recorded and reported in healthcare facilities 11 . Since resistance to multiple antibiotics among MRSA isolates is very common, there is a possibility of extensive outbreaks, which may be difficult to control. MRSA is now one of the commonest nosocomial pathogens, and asymptomatically colonized healthcare workers are the major sources of MRSA in the hospital environment. Early detection of MRSA and formulation of effective antibiotic policy in tertiary care hospitals is of paramount importance from the epidemiological point.
In our study a total of 350 clinical specimen positive for Staphylococcus aureus were obtained and assessed for methicillin resistance. Out of these 130 (37.14%) were found to be Methicillin resistant. Thus prevalence of Methicillin resistant S. aureus was found to be 37.14% in present study. Prevalence of MRSA has been shown to vary substantially in some contemporary clinical series from the region. Table D1 shows the prevalence of MRSA in some contemporary clinical series: In present study, Kirby Bauer disc diffusion method (Cefoxitin 30 mg) proved to be more sensitive than Oxacillin resistance agar method for detection of MRSA. This finding is in accordance with the observations made by Datta et al. who also showed that Cefoxitin disc diffusion is more sensitive than Oxacillin resitance agar method in the detection of MRSA 16 .
In present study, pus was the most common source of MRSA (39.23%) followed by urine (37.69%), sputum (8.46%) and catheter tip (7.69%) respectively. Saikia et al. (2009) 12 also showed maximum isolation of MRSA from pus/wound swabs (46.67%) followed by sputum/throat swab (42.86%) while Ahmad et al. 13 found source of MRSA to be 22.2% from pus, 23.8% from wound swabs, 33.3% from aspirates and 13.3% from sputum. The findings of present study are in accordance with the observations of Tiwari et al. 14 (2011) who reported pus (45%) followed by urine (20.5%) to be the major source of MRSA in their study. With slight difference in proportions, these two sources comprise the major source of MRSA in our study too. In present study, MRSA positivity rate in pus samples was significantly higher (51/84; 60.7%) as compared to other specimen (79/266; 29.7%). This finding is in accordance with some other studies too that have also reported pus to have a higher MRSA positivity rate as compared to other specimen 12,14,15 .
MRSA specimens were most sensitive against Vancomycin (100.0%) and Linezolid (93.85%). Cefoxitin, Ciprofloxacin and Clindamycin showed maximum resistance (100%, 53.38% and 42.31% respectively). The antibiotic susceptibility has been reported to vary substantially in different studies. Goyal et al(2013) 17 showed from a study conducted in a teaching hospital at Agra that MRSA specimens were most sensitive against  19 Bhubaneswar,India who showed all the isolated MRSA strains were sensitive against Vancomycin and Linezolid(100%).Vancomycin and Linezolid are most sensitive drugs with most of the studies reporting their sensitivity rates between 90% to 100%. The findings of present study also emulated the same and showed vancomycin and linezolid to be 100% and 93.85% sensitive. For other conventional antibiotics different studies have shown a high resistance pattern. A number of studies have also reported multiresistance. In present study too for conventional antibiotics the resistance rates were ranged from 42.31% to 100%. A number of specimen were polyresistant too.
These findings in turn indicate the need to develop a antibiotic protocol dependent on MRSA profile of the pathogen in order to reduce the unnecessary burden ofantibiotics. The findings of present study, thus showed that MRSA was prevalent in our hospital. There is a progressive increase in MRSA positivity and multi-drug resistance in strains of Staphylococci. vancomycin and linezolid were found to have absolute sensitivity.