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Year : 2002  |  Volume : 20  |  Issue : 1  |  Page : 45-46

Species distribution and antibiotic sensitivity pattern of coagulase negative staphylococci isolated from various clinical specimens

Department of Microbiology, Government Medical College, Amritsar - 143 001, Punjab, India

Correspondence Address:
Department of Microbiology, Government Medical College, Amritsar - 143 001, Punjab, India

 ~ Abstract 

A study of 192 strains of Coagulase negative staphylococcus (CONS) showed that Staphylococcus epidermidis was the most common species, 158 (82.29%) isolated from all clinical specimens followed by S. saprophyticus (30, 15.62%) isolated mainly from urine. Slime production was exhibited by 77 (48.7%) strains of S. epidermidis and 8 (26.6%) of S. saprophyticus and the difference in the slime producing activity was statistically significant (p<0.005). Antibiotic susceptibility testing against 15 commonly used antibiotics showed multidrug resistance with more than 90% resistance to penicillin, more than 50% to cephalexin and ciprofloxacin and more than 20% to methicillin, thus, highlighting the importance of species identification and antibiotic susceptibility testing for clinical isolates of CONS.

How to cite this article:
Mohan U, Jindal N, Aggarwal P. Species distribution and antibiotic sensitivity pattern of coagulase negative staphylococci isolated from various clinical specimens. Indian J Med Microbiol 2002;20:45-6

How to cite this URL:
Mohan U, Jindal N, Aggarwal P. Species distribution and antibiotic sensitivity pattern of coagulase negative staphylococci isolated from various clinical specimens. Indian J Med Microbiol [serial online] 2002 [cited 2021 Mar 1];20:45-6. Available from:

Coagulase negative staphylococci (CONS), previously dismissed as contaminants are now emerging as important potential pathogens with the increase in number of severely debilitated patients and increased use of implants in hospitals. More than 30 species of CONS are recognised but only a few are commonly incriminated in human infections. Multidrug resistant strains are common.[1] It was therefore planned to study the species distribution and antibiotic sensitivity pattern of CONS isolated from various clinical specimens received in the bacteriology laboratory of Medical College, Amritsar.

 ~ Materials and Methods Top

A total of 192 strains of CONS isolated from urine (93), pus (34), drain tips/catheter tips/I.V. cannulas (22), blood (9), and skin and conjunctival swabs (19 each) and aural swabs (4) were subjected to species identification,[2] slime production[3] and antibiotic susceptibility testing.[4] For assessing the clinical relevance, various criteria adopted by Deighton et al [5] were employed.

 ~ Results Top

S. epidermidis was the most commonly isolated species 82.3% (158/192) and included all the isolates from drain tips/catheter tips/I.V. cannulas, blood, skin and aural swabs and 94% (32/34) isolates from pus. S. saprophyticus was the second important species 15.6% (30/192), isolated mostly from urine specimens where its pathogenic potential is well documented.5-7 Only two other species of CONS were identified S. cohnii (1) and S. haemolyticus (3).
Slime production, an important colonizing and virulence factor in CONS was found to be positive in 77/158 (48.7%) strains of S. epidermidis and 8/30 (26.7%) of S. saprophyticus. The difference was statistically significant (p<0.05) and correlated with the findings of Pathak et al.[7] S. saprophyticus isolates in our study were found to be urease positive.
The results of antibiotics susceptibility testing are given in the [Table].

 ~ Discussion Top

Only 85 (44.3%) isolates were assessed to be clinically relevant. Isolates from catheter tips etc. were disease associated in maximum number, 19/22 (86.4%) followed by those from urine specimens 52/93 (56%). This is similar to the findings of other workers who reported the pathogenic role of S. epidermidis in catheter related sepsis[5],[7] and that of S. saprophyticus in UTI.[1],[6],[7]
Results of antibiotic susceptibility testing showed multidrug resistance and variability in sensitivity and resistance patterns, similar to the studies of Goel et al [9] and Pathak et al.[7] In our study, maximum resistance was observed towards penicillin (90.6%) followed by Nalidixic acid (83.8%), norfloxacin (62.5%), cephalexin (54.6%), ciprofloxacin (51%), gentamicin (46.3%) and chloramphenicol (40%). All the isolates were sensitive to vancomycin. Variability in the antibiotic susceptibility pattern of CONS has been observed by various authors5, 9,10 which positively reflects the different protocols and panels of antibiotics being used in different hospitals and difference in the geographical locations from where these isolates have been obtained. It is therefore suggested that to fully assess the importance of CONS, it may be essential to determine its species and antibiotic sensitivity as no particular pattern can be predicted in any problematic situation. 

 ~ References Top

1.Geary C, Jordens JZ, Richardson JF, Howcraft DM, Mitchell CJ. Epidermiological typing of Coagulase negative staphylococci from nosocomial infections. J Med Microbiol 1997; 46:195-203.  Back to cited text no. 1    
2.International Bulletin of Bacterial Nomenclature.1976; 26:332.  Back to cited text no. 2    
3.Christensen GD, Simpson WA, Bisno AL, Beachy EH. Adherence of slime producing strains of Staphylococcus epidermidis of smooth surfaces. Infect Immun 1982; 32:318.  Back to cited text no. 3    
4.Bauer AW, Kirby WMM, Sherris JC, Turck M. Antibiotic susceptibility testing by a standardized single disc method. Am J Clin Pathol 1966; 45:493.  Back to cited text no. 4    
5.Deighton MA, Franklin JC, Spicer WJ, Bulkan B. Species identification, antibiotic sensitivity and slime production of Coagulase negative staphylococci isolated from clinical specimens. Epidemiol Infect 1988; 101;99-113.   Back to cited text no. 5    
6.Shrikhande S, Thakar YS, Pathak AA, Saoji AM. Species distribution of clinical isolates of Staphylococci. Ind J Pathol Microbiol 1996; 39(3): 207-210.   Back to cited text no. 6    
7.Pathak J, Udgaonkar U, Kulkarni RD, Pawan SW. Study of Coagulase negative staphylococci and their incidence in human infections. Ind J Med Microbiol 1994; 12(2): 90-95.  Back to cited text no. 7    
8.Rathinam K, Shanmugam J, Rout D. Slime production by Coagulase negative staphylococcal species isolated from hospitalised patients, healthy carriers and environments. Indian J Med Microbiol 1993; 17:243-246.   Back to cited text no. 8    
9.Goel MM, Singh AV, Mathur SK, Mastan Singh, Singhal S, Chaturvedi UC. Resistant Coagulase negative staphylococci from clinical samples. Indian J Med Res 1991; 93:350-352.   Back to cited text no. 9    
10.Saini S, Kaur U, Sabharwal U, Malik K. Coagulase negative staphylococci in the urinary tract. Ind J Med Res 1983; 78:26.  Back to cited text no. 10    
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