|Year : 2015 | Volume
| Issue : 2 | Page : 68-70
Increasing trend of community-acquired methicillin-resistant: Staphylococcal carriers: An alarming bell for urgent measures
Poongodi Lakshmi Santhana Kumarasamy1, Palaniappan Nainar2
1 Department of Microbiology, Tirunelveli Medical College, Tirunelveli, Tamil Nadu, India
2 Department of Microbiology, Madurai Medical College, Madurai, Tamil Nadu, India
|Date of Web Publication||14-May-2015|
Poongodi Lakshmi Santhana Kumarasamy
Department of Microbiology, Tirunelveli Medical College, Highgrounds, Tirunelveli - 627 011, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Background: An increase in the incidence of infections caused by community-associated-methicillin resistant Staphylococcus aureus (MRSA) has been reported. Hence, the knowledge of resistance pattern of these isolates is a precondition for alleviating emerging antibiotic resistance and devising better treatment strategies Aim: To find out the prevalence of community-acquired methicillin-resistant staphylococcal strains from nasal carriers. Materials and Methods: A total of 352 nasal swabs collected during routine health checkup were analyzed. Results: Of the 58 (16%) staphylococci isolated, 32 (55%) were S. aureus and 26 (45%) were coagulase-negative staphylococci (CoNS). Methicillin resistance was observed in 7 (22%) of staphylococci aureus and 11 (42%) of CoNS. "D test" was positive in 1 (14%) MRSA, 2 (8%) methicillin-susceptible S. aureus and 2 (8%) methicillin resistant-CoNS. Conclusion: Effective implementation of the antibiotic policy along with measures like hand wash, isolation of patients will reduce the incidence of resistance.
Keywords: Antibiotic policy, carriers, community-associated-methicillin resistant Staphylococcus aureus, "D" test
|How to cite this article:|
Kumarasamy PL, Nainar P. Increasing trend of community-acquired methicillin-resistant: Staphylococcal carriers: An alarming bell for urgent measures. J Sci Soc 2015;42:68-70
|How to cite this URL:|
Kumarasamy PL, Nainar P. Increasing trend of community-acquired methicillin-resistant: Staphylococcal carriers: An alarming bell for urgent measures. J Sci Soc [serial online] 2015 [cited 2020 Aug 7];42:68-70. Available from: http://www.jscisociety.com/text.asp?2015/42/2/68/157030
| Introduction|| |
Today drug resistance has increased manifold. Hence a simple staphylococcal skin infection can lead to serious life-threatening infections. Multidrug resistance is a rule in healthcare-associated-methicillin resistant S. aureus (MRSA) strains, which create difficulties in choosing the right drug for right bug empirically. Newer drugs are only slight structural modifications of previous generations with a little functional difference. Discovery of new drug remains a dream; it takes at least 10 years and involves crores of money. Further, an increase in the incidence of infections caused by community-associated-MRSA (CA-MRSA) has been reported.  Hence, the knowledge of resistance pattern of these isolates is a precondition for alleviating emerging antibiotic resistance and devising better treatment strategies. This study was carried out to find out the prevalence of community-acquired methicillin-resistant staphylococcal strains from nasal carriers.
| Materials and methods|| |
A total of 352 nasal swabs were collected from general population attending routine health check-up camp in Tirunelveli, Tamil Nadu during January 2012. Informed consent, filled in proforma and institutional ethical committee clearance were obtained. All the samples were streaked directly on mannitol salt agar (HiMedia) and the isolates were identified as staphylococci by standard biochemical techniques. Antimicrobial susceptibility testing was done by Kirby-Bauer's disc diffusion method as per Clinical and Laboratory Standards Institute guidelines using penicillin (10 IU), cefoxitin (30 μg), gentamycin (10 μg), amikacin (30 μg), ciprofloxacin (5 μg), erythromycin (15 μg), vancomycin (30 μg) linezolid (30 μg) and mupirocin (5 μg). The isolates which were resistant to erythromycin were subjected to "D test." All MRSA strains were plated on CHROM agar (HiCrome MeReSa Agar base-M1674) for further confirmation. Control strain used was ATCC 25923.
| Results|| |
Of the 352 swabs, 58 (16%) were culture positive for staphylococci. Of this 58 isolates, 32 (55%) were identified as S. aureus and 26 (45%) as coagulase negative staphylococci (CoNS). Of the 32 S. aureus strains, 7 (22%) were MRSA by disc diffusion and it was further confirmed by CHROM agar. Of the 26 CoNS strains, 11 (42%) were methicillin resistant-CoNS (MR-CoNS). "D test" was positive in 1 (14%) MRSA, 2 (8%) methicillin susceptible S. aureus (MSSA) and 2 (8%) MR-CoNS. Constitutive MLS B resistance was observed in 2 (8%) MSSA strains. MS phenotype was observed in 5 (71%) MRSA, 8 (32%) MSSA, 4 (36%) MR-CoNS and 5 (33%) MS-CoNS. All the strains (100%) were sensitive to vancomycin, linezolid and mupirocin. Of the 58 isolates, 47 (81%) were resistant to penicillin, 11 (19%) were sensitive to both penicillin and cefoxitin, 28 (48%) were penicillin resistant and cefoxitin sensitive, 19 (33%) were resistant to both penicillin and cefoxitin. 29 (50%) were resistant to erythromycin, 17 (29%) were resistant to ciprofloxacin.
| Discussion|| |
Antibiotic resistance was reported even before the introduction of antibiotics.  Staphylococcus is a human pathogen with a phenomenal propensity for the development of antibiotic resistance.
In the present study, 22% MRSA and 42% MR-CoNS were reported. Similar observation was made by Oommen et al., as 29% MRSA, 23% MR-CoNS.  CHROM agar is a rapid, selective and easy method with high sensitivity and specificity in the detection of MRSA directly from clinical samples.
Community-associated-methicillin resistant S. aureus strains usually cause skin and soft tissue infections, but can also cause serious systemic infections such as pneumonia and fascitis.  Further, the burgeoning increase in the beta-lactam resistance, restricts the therapeutic options.
In the present study, 29 (50%) were resistant to erythromycin, which were resistant either through erm or msrA genes. Strains with erm-mediated resistance may show inducible clindamycin resistance, but may appear susceptible to clindamycin by disc diffusion in nonadjacent position.  In this study, inducible clindamycin resistance was noted among 1 (14%) MRSA. Fiebelkorn et al. reported iMLS B as 28%, Yilmaz et al. as 24.4%, Ajantha et al. as 74% and Deotale et al. as 45% in MRSA. ,,, Clindamycin is not a befitting alternative drug in these cases. Hence, all the staphylococcal isolates should be tested for inducible clindamycin resistance, to prevent therapeutic failure.
Constitutive MLS B resistance was observed in 2 (8%) MSSA strains. Angel MR reported this as 25%.  These strains are resistant to all MLS B antibiotics, which can be detected by the routine disk diffusion method.
Disk diffusion by vancomycin 30 μg detect VISA stains as fully susceptible. The gold standard test for the detection of vancomycin resistance is minimum inhibitory concentration determination by broth or agar dilution or by E-test  but these tests are either costly or difficult to perform routinely in diagnostic laboratories.
In this study, all the staphylococcal isolates were sensitive to linezolid. This was supported by Gupta et al. and Srinivasan et al. , Hence, linezolid is a hopeful therapeutic option in the era of increasing antibiotic resistance. All the strains (100%) were sensitive to mupirocin, which still remains the choice of drug for nasal clearance of MRSA carriers. Sarma and Ahmed also observed 100% mupirocin sensitivity among MRSA strains. 
| Conclusion|| |
Antimicrobial resistance is a life and death problem that strikes at the crux of infectious disease control. Its global spread endangers global health security, further it affects the economy, international trade and tourism. Antibiotic policy making and effective implementation will only reduce the incidence of antimicrobial resistance along with other measures like hand wash, isolation of patients with MDR strains, avoiding indiscriminate antibiotic use by physicians, agriculturist and veterinarians, prescription only by registered practitioners and community education. This is possible only by the coordinated effort of targeting the specific pathogen with narrow spectrum antibiotics, use of bactericidal agents and empirical therapy based on the prevalent organisms in the environment and its sensitivity pattern.
| Acknowledgments|| |
All persons who have made substantial contributions to the preparation of the manuscript, but who are not authors are named in the acknowledgement section and have agreed in writing to be named. No contributor has been omitted.
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