|Year : 2001 | Volume
| Issue : 3 | Page : 138-140
Antimicrobial susceptibility pattern among methicillin resistant staphylococcus isolates in Assam
D Majumder , JN Sarma Bordoloi , AC Phukan , J Mahanta
Prevalence of methicillin resistant Staphylococcus aureus from a referral hospital in Assam was studied. Methicillin resistance among the Staphylococcus aureus isolates was 52.9% and 15% among the coagulase negative staphylococci. Resistance to all antibiotics tested among the methicillin resistant and methicillin sensitive staphylococci was found to be 23.2% and 6.6% respectively. Higher resistance to multiple antibiotics in methicillin resistant strains as compared to methicillin sensitive strains was found to be statistically significant. Ciprofloxacin resistance among the strains was still lower in comparison to the findings from other parts of the country.
|How to cite this article:|
Majumder D, Bordoloi JS, Phukan A C, Mahanta J. Antimicrobial susceptibility pattern among methicillin resistant staphylococcus isolates in Assam. Indian J Med Microbiol 2001;19:138-40
|How to cite this URL:|
Majumder D, Bordoloi JS, Phukan A C, Mahanta J. Antimicrobial susceptibility pattern among methicillin resistant staphylococcus isolates in Assam. Indian J Med Microbiol [serial online] 2001 [cited 2019 Sep 23];19:138-40. Available from: http://www.ijmm.org/text.asp?2001/19/3/138/8147
Resistance to multiple antibiotics among the Staphylococcus isolates in hospitals has been recognized as one of the major challenges in hospital infection control. Life threatening sepsis, endocarditis and osteomyelitis caused by methicillin resistant Staphylococcus aureus (MRSA) have been reported from several parts of the world., Since MRSA strains are also resistant to multiple antibiotics, there is possibility of extensive outbreaks, which may be difficult to control. MRSA is now one of the commonest bacteria causing nosocomial infections., High prevalence of MRSA in referral hospitals have also been reported from India and neighboring countries.,,
Early detection of MRSA and formulation of effective antibiotic policy in referral hospitals are of paramount importance from the hospital epidemiological point. However, the status of MRSA in large hospitals of Northeastern region of India with a population of more than 35 million is very scanty. Prevalence and antibiotic sensitivity pattern of MRSA help the treating clinicians for first line treatment in these referral hospitals. The present study has been carried out in one of the major tertiary referral hospitals of this region with an aim to know the antibiotic sensitivity pattern of staphylococcal isolates with special reference to MRSA.
| ~ Materials and Methods|| |
This study was carried out in Assam Medical College Hospital, which caters to the health care needs of upper Assam, with an average annual out patient attendance of about 2,60,000 and indoor admission of 26,000. A total of 313 strains of Staphylococci isolated from persons having different staphylococcal diseases (196) and apparently healthy staff working in hospital (117) was included in the study. Samples to isolate MRSA from healthy persons were collected following the method described by Na'was and Fakhoury with sterile cotton swab from anterior nares and were immediately placed in nutrient broth containing 7.5% sodium chloride for further processing in the laboratory. All the isolates were tested for coagulase test following standard procedures. Sensitivity to penicillin, gentamicin, tetracycline, erythromycin and ciprofloxacin were carried out following Stokes' or modified Stokes disc diffusion method. The strains were tested for methicillin resistance following procedures described elsewhere. For disc diffusion tests; with 1µg Oxacillin discs (Mast diagnostics, Merseyside, U.K.) Muellar Hinton agar (Hi-Media, Bombay, India) containing 4% NaCl were used. Retesting was also done using 5µg methicillin disc separately following same procedure and media. NCTC- 6571 Staphylococcus aureus was used in each plate as control.
| ~ Results|| |
Out of 313 isolates of staphylococci, 223 strains were coagulase positive and 90 were coagulase negative. Out of 223 strains, 106 were isolated from patients and 117 from apparently healthy carriers. A total of 118 (52.9%) of the coagulase positive staphylococcal strains showed resistance to methicillin (Table) and 14 (15%) coagulase negative strains showed methicillin resistance. On further analysis it was seen that 25 (23.6%) staphylococcal isolates from patients (106) showed methicillin resistance as against 93 (79.5%) out of 117 isolates from carriers.
Methicillin resistance was consistent when tested with Oxacillin as well as methicillin in coagulase positive strains but 4% of coagulase negative strains showed sensitivity with methicillin discs though they were labeled as resistant with oxacillin discs. As many as 32 (23.2%) staphylococcal strains were resistant to all the antibiotics tested and 12 (6.6%) were resistant to all other antibiotics except methicillin. Co-existing resistance to different antibiotics (except penicillin) with methicillin was significantly higher in comparison to methicillin sensitive strains (p<0.05 to p<0.001). Highest number of strains showed resistance to penicillin followed by gentamicin, tetracycline, erythromycin and ciprofloxacin. Co-existing ciprofloxacin and methicillin resistance was seen in 23.2% of strains, whereas among the methicillin sensitive strains ciprofloxacin resistance was only 6.6%.
| ~ Discussion|| |
The present study highlights the problem of MRSA in a referral hospital in Assam. Since this hospital caters to the health care needs of whole of Upper Assam districts, the picture reflects the situation in upper Assam. High prevalence of MRSA has been recorded in many tertiary care hospitals.,, Though prevalence of MRSA was found to be similar to Vellore in the present study, yet it is very high in comparison to the records of other hospitals in India.,, Isolation of coagulase negative Staphylococcus and antibiotic sensitivity patterns are regarded with all seriousness in clinical practice and clinical epidemiology, because these strains are not only resistant to multiple antibiotics, but also act as a reservoir for drug resistance gene. Prevalence of methicillin resistance among coagulase negative staphylococci isolates of our study was low in comparison to other studies elsewhere but similar to Vellore (south India). About 80% of the isolates, from carriers were resistant to methicillin as against about 24% from the patients. This may be due to presence of community acquired strains among patients, where methicillin resistance is expected to be low as compared to hospital environment. Further , these strains were resistant to multiple antibiotics. However, there is not much difference between these groups as regard to their antibiogram. Higher percentage of methicillin resistant staphylococci among carriers can serve as a focus of nosocomial spread of multidrug resistant staphylococci in tertiary hospitals and cause problems to hospital infection control agencies. High prevalence of resistance among Staphylococcus aureus to commonly used anti-microbial agents is known. Multi-drug resistance among MRSA strains has been reported.14 In our study too resistance to different antibiotics among MRSA strains was significantly higher than those, which were sensitive to methicillin. Ciprofloxacin, which was proposed to be an alternative therapy to MRSA infection, were found to be still better in this part of the country (23%), than in Pondicherry, where ciprofloxacin resistance was shown to be very high.5 This is perhaps due to the differential clonal expansion and drug pressure in the community.
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