Indian Journal of Medical Microbiology Home 

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

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

U Mohan, N Jindal, P Aggarwal 
 Department of Microbiology, Government Medical College, Amritsar - 143 001, Punjab, India

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


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;20:45-46

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 Jan 25 ];20:45-46
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Full Text

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

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.


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 (pS. saprophyticus isolates in our study were found to be urease positive.

The results of antibiotics susceptibility testing are given in the [Table].


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.


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