• Users Online: 37364
  • Home
  • Print this page
  • Email this page

   Table of Contents      
ORIGINAL ARTICLE
Year : 2007  |  Volume : 55  |  Issue : 1  |  Page : 9-13

Phenotypic and plasmid pattern analysis of Staphylococcus epidermidis in bacterial keratitis


Department of Microbiology and Cornea Services, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India

Date of Submission30-Jan-2006
Date of Acceptance17-Oct-2006

Correspondence Address:
Niranjan Nayak
Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi - 110 029
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0301-4738.29488

Rights and Permissions
  Abstract 

Background: Staphylococcus epidermidis , a commensal of the conjunctival sac has been incriminated as the commonest etiological agent of bacterial keratitis. However, the pathogenic potential of this commensal organism is not clearly known.
Aim: To determine any phenotypic, molecular markers of S. epidermidis pathogenicity in bacterial keratitis.
Materials and Methods: A total of 382 corneal ulcer isolates of S. epidermidis and 87 S. epidermidis isolates from healthy eyes (controls) were studied. Speciation, biotyping and antibiotic sensitivity testing were performed by conventional methods. Tube slime and adherence tests were carried out by recommended techniques. Plasmid analysis was conducted by a standard protocol.
Statistical Analysis: Chi-square test was employed for calculations.
Results: Out of 382 corneal ulcer isolates (Pathogens) 284 (74.3%) belonged to biotypes I and II. Slime was detected in 164 (42.9%) of 382 pathogens vs. 21 (24.1%) of 87 controls ( P <0.001). Sixty-five (39.6%) of 164 slime positive isolates were multidrug-resistant as compared to only 49 (22.4%) of 218 slime negative isolates ( P <0.001). A significantly higher number i.e., 73.1% (120/164) of slime-producers possessed a 21Kb plasmid in contrast to only 53.2% (116/218) of nonslime-producers ( P <0.001). Presence of this plasmid had a statistical correlation of low significance with multidrug resistance ( P =0.04). One hundred and seventy-two (45.0%) of 382 pathogens and 24 (27.6%) of the 87 controls were adherent to artificial surfaces ( P =0.003) and the majority of the adherent organisms (99/172, 57.6%) were slime producers ( P <0.001).
Conclusions:
Slime was associated with multidrug resistance in corneal ulcer isolates of S. epidermidis . The 21Kb plasmid could determine virulence as it was responsible for slime production and adherence.

Keywords: Adherence, coagulase-negative staphylococci , multidrug resistance, plasmid, slime.


How to cite this article:
Nayak N, Satpathy G, Vajpayee RB, Mrudula S. Phenotypic and plasmid pattern analysis of Staphylococcus epidermidis in bacterial keratitis. Indian J Ophthalmol 2007;55:9-13

How to cite this URL:
Nayak N, Satpathy G, Vajpayee RB, Mrudula S. Phenotypic and plasmid pattern analysis of Staphylococcus epidermidis in bacterial keratitis. Indian J Ophthalmol [serial online] 2007 [cited 2024 Mar 28];55:9-13. Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?2007/55/1/9/29488

Slime positivity amongst adherent and nonadherent
corneal ulcer isolates (Pathogens) of S. epidermidis


Click here to view
Slime positivity amongst adherent and nonadherent
corneal ulcer isolates (Pathogens) of S. epidermidis


Click here to view
Multidrug resistance amongst 382 corneal ulcer
isolates (pathogens) with and without the 21 Kb plasmid


Click here to view
Multidrug resistance amongst 382 corneal ulcer
isolates (pathogens) with and without the 21 Kb plasmid


Click here to view
Presence of 21 Kb plasmid amongst slime-positive
and slime-negative corneal ulcer isolates (pathogens)


Click here to view
Presence of 21 Kb plasmid amongst slime-positive
and slime-negative corneal ulcer isolates (pathogens)


Click here to view
Slime production vs. multidrug resistance amongst
the corneal ulcer isolates (Pathogens)


Click here to view
Slime production vs. multidrug resistance amongst
the corneal ulcer isolates (Pathogens)


Click here to view
Biotypes of the isolates

Click here to view
Biotypes of the isolates

Click here to view
Slime positivity amongst corneal ulcer isolates
(pathogens) and commensals


Click here to view
Slime positivity amongst corneal ulcer isolates
(pathogens) and commensals


Click here to view
Infectious keratitis of bacterial origin is a leading cause of ocular morbidity and blindness in India.[1] Staphylococcus epidermidis , one of the normal flora of the conjunctival sac, accounts for nearly 43-45% of the total cases of bacterial keratitis.[2] However, the pathogenicity of this commensal organism in corneal infection has partly been elucidated only recently.[3] A previous study in this context showed a significantly higher rate of isolation of slime-producing S. epidermidis from corneal ulcer patients than from controls.[4]

Nevertheless, the exact way of acquisition of such pathogenic potential by this commensal bacterium is so far not clearly known. Moreover, it is very difficult in a clinical bacteriology laboratory, to discriminate between an infecting and a noninfecting isolate of S. epidermidis from a case of ulcerative keratitis.

The aim of this study was to elucidate any phenotypic and/or molecular marker(s) of virulence of this organism and the clinical implications of these markers in corneal ulcer pathogenesis.


  Materials and Methods Top


We studied 382 S. epidermidis isolates from 382 patients of infectious keratitis, who attended the outpatient department or were admitted to the wards of Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi during the period February 2001 to December 2004. In addition, another 87 S. epidermidis isolates from subjects of cataract, who reported for preoperative bacteriological checkup were included as controls. Methods for sample collection and isolation procedures were according to those described earlier.[4] All isolates were identified and speciated according to the Baird-Parker´s modified scheme[5] of the original method of Kloos and Schleifer.[6] Antibiotic sensitivity testing was performed by the standard disc diffusion technique.[7] The antibiotics (Himedia, Mumbai, India) tested with their respective concentration/disc (mg) were tetracycline(30), chloramphenicol(10), gentamicin(10), cloxacillin(1), ciprofloxacin(5), tobramycin (10), vancomycin(30) and cephazolin(30). An organism showing resistance to three or more antibiotics was regarded as multidrug resistant.[8]

All the 382 corneal ulcer isolates (pathogens) as well as the 87 controls (commensals) were biotyped according to the standard procedure by employing Voges-Proskauer test, phosphatase test and fermentations of lactose, maltose and mannitol.[9] Both the corneal ulcer isolates (pathogens) as well as the control strains (commensals) were tested for slime production by the recommended tube slime method as described earlier.[10]

Adherence of each isolate to smooth surfaces was determined quantitatively by a method earlier standardized in our laboratory.[3] Briefly, overnight cultures of bacteria in trypticase soy broth (Himedia, Mumbai, India) were diluted one in 100 in fresh trypticase soy broth, and 1 ml volume of each was taken in separate quartz cuvettes. After overnight incubation at 37°C, the cuvettes were washed four times with phosphate buffered saline and then fixed with Bouin's fluid and stained with crystal violet. Excess stain was removed by decanting the cuvettes first and then rinsing them gently with tap water. The optical density (OD) of the stained bacterial biofilm was read with spectrophotometer (Spectrocolorimeter 103, Systronics, Baroda, India) at 570 nm. The cutoff OD was calculated, which was three times the standard deviation (SD) above the mean OD of 10 blanks stained exactly by the same procedure (0.37).

Plasmid was extracted from the whole cell lysate of the bacterial cell by a crude lysis technique as described earlier[11] with certain modifications. Briefly, 1.5 ml aliquots were collected by centrifugation in Eppendorf Centrifuge tubes from the log phase growth of bacteria. The cells were then resuspended in 60 ml of lysis buffer (0.005 M EDTA, 0.01 M Tris, 25% (w/v) Sucrose, 0.5 mg/ml of Pancreatic RNAase, 0.2 mg/ml of lysostaphin [pH 8,5]), incubated at 37°C for two hours and lysed by the addition of 75 ml of 4% (w/v) sodium dodecyl sulphate. The lysate was then frozen at -70°C, thawed at 60°C and vertexed and to it was added an equal volume of the solution containing acetic acid and 5 M ammonium acetate (1.15 ml and 6.0 ml respectively in 2.85 ml of H 2 O). Then the mixture was gently shaken by inverting the tube several times, stored in ice for 3-5 min, then centrifuged at 12000 rpm for 5 min at 4°C. The supernatant was collected in fresh Eppendorf tubes and to it was added an equal volume of phenol chloroform mixture and fresh supernatant was collected after recentrifuging at 12000 rpm for two minutes. The DNA was then precipitated by isopropyl alcohol and the precipitated DNA was stored in Tris EDTA buffer pH 8.0 after two washings with 70% ethanol. A 5 ml portion was then run on 1% agarose gel at 90 volts. A molecular standard, (DNA/ECO RI digest, Bangalore geine Pvt. Ltd., New Delhi, India) was run with the samples along the gels.


  Results Top


Out of a total of 469 S. epidermidis isolates studied, 164 (42.9%) of the 382 isolates from patients (pathogens) and 21 (24.1%) out of 87 from controls (commensals) were positive for slime ([Table - 1], P < 0.001). Thus, overall slime positivity was noticed in 39.4% (185/469) of the isolates.

Amongst the 382 corneal ulcer isolates, (pathogens) 177 (46.3%), 107 (28.0%), 58 (15.1%) and 40 (10.5%) belonged respectively to S. epidermidis biotype II, I, III and IV [Table - 2]. The majority i.e., 284 (74.3%) of the corneal ulcer isolates were biotypes I and II. These two types were also predominant amongst the 164 slime-positive corneal ulcer isolates (81 belonged to biotype II, 55 to biotype I and 14 each to biotype III and IV). However, amongst the 87 commensals, 47 were of biotype III, 24 of biotype IV, seven of biotype II and nine biotype I.

[Table - 3] depicts the relationship between slime production and multidrug resistance among the 382 corneal ulcer isolates. Whereas 65 (39.6%) of 164 slime-positive isolates were found to be multidrug resistant, only 49 (22.4%) of 218 slime-negative isolates were found to be so. This difference was statistically significant ( P <0.001).

Plasmid analysis revealed that 236 (61.8%) out of 382 corneal ulcer isolates harbored a high molecular weight plasmid of 21Kb. However, 29 (12.3%) of these 236, shared additional bands suggesting that these 29 bacteria carried multiple plasmids [Figure - 1]. A significantly higher number i.e., 120 (73.1%) of the 164 slime producers did possess this plasmid as compared to 116 (53.2%) of 218 nonslime produces ([Table - 4], P < 0.001). However, the presence of this high molecular weight plasmid had a statistical correlation of low significance with the multidrug resistance phenomenon ([Table - 5], P = 0.04), although the 29 bacteria which possessed multiple plasmids were all found to be multidrug resistant.

The result of the quantitative adherence assay as described in the materials and methods is depicted in [Figure - 2]. Out of all the 382 corneal ulcer isolates studied for the quantitative adherence test, 172 (45.0%) were adherent and 210 (54.9%) nonadherent [Figure - 2]. Whereas 99 (57.6%) of the 172 adherent organisms were slime producers, only 65 (30.9%) out of 210 nonadherent organisms were found to be slime producers ([Table - 6], P < 0.001) suggesting thereby that slime could mediate S. epidermidis adherence to artificial surfaces.


  Discussion Top


Infectious keratitis due to S. epidermidis is reported to be quite high,[2],[12],[13],[14] even though this organism is regarded as part of the normal conjunctival flora. We had earlier determined the significance of S. epidermidis , and the increased pathogenicity of slime-producing strains of S. epidermidis in bacterial keratitis.[3],[4] The present study was undertaken with the aim of exploring the possibilities of any stable phenotypic and/or molecular marker for S. epidermidis in order to implicate an isolate to be a pathogen in ulcerative keratitis.

Like the previous ones,[3],[4] our present study also showed significantly higher number of slime-positive isolates from patients than from controls [Table - 1]. Earlier, Christensen et al .[12] and Diaz-Mitoma et al .[15] established the significance of slime production in S. epidermidis in extraocular infections.

In consideration of the above, it can thus be inferred that slime is an important virulence factor of S. epidermidis in bacterial keratitis. Most of the S. epidermidis (284 of 382, 74.3%) corneal ulcer isolates in our study belonged to biotypes I and II which is in agreement with the observations made earlier.[4],[16] Whereas 107 of 114 multidrug-resistant isolates belonged to biotypes I and II (data not shown), the majority i.e., 136 (82.9%) of the 164 slime-positive corneal ulcer isolates belonged to this category [Table - 2].

To our knowledge, no study in the past had ever compared biotyping with slime production and multidrug resistance. Since the majority of our slime-producing strains were multidrug-resistant [Table - 3], this indicated that keratitis-producing S. epidermidis belonged to biotypes I and II and slime and multidrug resistance were the two prime virulence factors. Hence, the practice often adopted in a routine clinical bacteriology laboratory of disregarding 10 or less number of pure colonies of S. epidermidis , denoting them as mere commensals, should never be encouraged, if they are slime-positive. In addition to being slime producers, the majority of the corneal ulcer isolates in our study, were capable of adhering to artificial surfaces [Table - 1]. At the same time, it was also found that significantly higher number of slime producers had this property of adherence [Table - 6]. The phenomenon of adherence being the prime factor in staphylococcal pathogenicity not only in the corneal disease process[13] but also in extra-ocular infections as well,[1],[12],[17] the above findings regarding adherence amongst slime-positive S. epidermidis isolates in our study, could well be attributed to the role of slime in inducing initial attachment leading further to the development of the ulcerative lesion.[1]

All these above-mentioned findings could establish only one thing: that slime was responsible for staphylococcal virulence,[4] not only by imparting multidrug resistance to the organism, but also by its potential for adherence. These were amply evidenced by our data showing a significantly higher number of slime-producing corneal ulcer isolates to be resistant to three or more antibiotics. Other workers[15],[16],[17],[18] also put forth similar views that slime not only facilitated the colonization of bacteria to the host tissue by preventing access of host defense mechanisms but also by protecting them from being killed or arrested by antibiotics. Although the association between multidrug resistance and slime production, as shown by us, was not exactly established by others, a definitely higher number of antibiotic-resistant strains were slime-positive, as reported by them.[18],[19],[20]

Since 236 (61.8%) of the 382 corneal ulcer isolates in our study harbored a 21Kb high molecular weight plasmid [Table - 5], we categorically looked for any association between the presence of this plasmid and multidrug resistance as well as between the presence of plasmid and slime production. Whereas we could find a definite correlation between slime and plasmid positivity, we were unable to detect multidrug resistance in the majority of plasmid-bearing organisms. Thus, from the aforementioned observations, it could be substantiated that the 21Kb plasmid could well be regarded as a molecular marker for slime production and hence for staphylococcal pathogenicity in bacterial keratitis. Arciola et al .[21] however, reported ica (intercellular adhesion) operon, especially icaA and icaD genes as molecular markers for slime production in staphylococcal strains from catheter-associated infections.

Since there was a correlation (although of low significance, [Table - 5], P =0.04) between multidrug resistance and possession of 21 Kb plasmid, the implication of this plasmid in multidrug resistance cannot be ignored altogether. Moreover, there were 29 isolates bearing multiple plasmids which were all found to be multidrug-resistant. Hence, it could be possible that plasmids of smaller molecular weight, other than the 21 Kb, could be responsible for antibiotic resistance. This is in agreement with the observations of previous studies[22],[23] on skin isolates of S. epidermidis which showed that plasmids of 5.5 Kb were responsible for resistance to antibiotics such as tetracycline, kanamycin and neomycin. To the best of our knowledge, ours is the first independent observation of plasmid pattern analysis in ocular isolates of S. epidermidis . Archer et al .[11] however, analyzed the plasmid profile of S. epidermidis isolates in patients with prosthetic valve endocarditis and found that 93% of their isolates possessed plasmids of <10 megadalton size and 79% of the strains contained two or more plasmids. This is in contrast to our observations, because we could get approximately 21Kb plasmids in 61.8% of our isolates, only 29 (7.6%) having more than one plasmid. Ours being all ocular isolates, the sites of colonization of these isolates were totally different from those studied by Archer et al .[11] Thus, possession of a different class of plasmids by the ocular isolates might reflect different degree of virulence and differing pathogenicity. In related studies, the investigators studied only the plasmid profile of various S. epidermidis strains either as an epidemiological marker[24] or as a marker to differentiate infecting from noninfecting S. epidermidis in bloodstream infections.[11]

There are some limitations to the use of slime test in the routine laboratory practice. This is due to certain unequivocal test results, at times encountered in the tube slime detection method,[12] which may be owing to the observational bias in the visual interpretation of the result of a weakly slime-positive strain, that may, sometimes, be difficult to differentiate from the result of a control (nonslime-producing) strain. Moreover, tube test takes a minimum of 48h to denote a good slime positivity as compared to the Congo red Agar test which takes only 24h to do so.[10] Although the tube method is a very good qualitative technique, considering its shortcomings, the alternative method like Congo red Agar test could be employed with very good results by 24h.[10] Moreover, the Congo red Agar method has significant clinical applicability because it can be used in a routine diagnostic bacteriology laboratory. Because of its rapidity the results of the test could be provided along with the final culture and sensitivity report on the second postinoculation day i.e., within 48h of receiving the sample, thus, ascribing the isolate as having a pathogenic potential and not as a mere commensal.

It is concluded that the 21Kb plasmid present in the corneal ulcer isolates of S. epidermidis was a virulence plasmid and could be responsible for slime production and adherence. However, the multidrug resistance amongst the isolates in ulcerative keratitis was due to slime. Molecular studies are, however, required to further characterize corneal ulcer isolates of S. epidermidis in terms of their ica A and D loci[21] so that the exact molecular mechanisms of pathogenicity could be established.


  Acknowledgement Top


The study was supported by a research grant from the Indian Council of Medical Research, New Delhi.

 
  References Top

1.
Agarwal V, Biswas J, Madhavan HN, Mangat G, Reddy MK, Saini JS, et al . Current perspectives in infectious keratitis. Indian J Ophthalmol 1994;42:171-91.  Back to cited text no. 1
    
2.
Satpathy G, Vishalakshi P. Ulcerative keratitis: Microbial profile and sensitivity pattern: A five year study. Ann Ophthalmol 1995;27:301-6.  Back to cited text no. 2
    
3.
Nayak N, Satpathy G, Vajpayee RB, Sethi A, Ray M, Sinha R. Clinical significance of slime production by S. epidermidis in bacterial keratitis. Ann Ophthalmol 2002;34:204-10.  Back to cited text no. 3
    
4.
Nayak N, Satpathy G. Slime production as a virulence factor in Staphylococcus epidermidis isolated from bacterial keratitis. Indian J Med Res 2000;111:6-10.  Back to cited text no. 4
[PUBMED]    
5.
Baird-Parker AC. Methods for identifying Staphylococci and Micrococci: In : Skinner FA, Lovelock DW, editor. Identification methods for Microbiologists, The Society for Applied Microbiology Technical Series No.14: Academic Press: London. 1979. p. 201-10.  Back to cited text no. 5
    
6.
Kloos WE, Schleifer KH. Simplified scheme for routine identification of human Staphylococcus species. J Clin Microbiol 1975;1:82-8.  Back to cited text no. 6
[PUBMED]  [FULLTEXT]  
7.
Bauer AW, Kerby WM, Sherris JC, Turck M. Antibiotic susceptibility testing by a standardised single disc method. Am J Clin Pathol 1966;45:493-6.  Back to cited text no. 7
    
8.
Landonan D, Mobarakai NK, Quale JM. Novel antibiotic regimens against Enterococcus faecium resistant to ampicillin, vancomycin and gentamicin. Antimicrobial Agents Chemother 1993;37:1904-8.  Back to cited text no. 8
    
9.
Parker MT . Staphylococcus and Micrococcus; The anaerobic Gram positive cocci. In : Parker MT, editor. Topley and Wilson's Principle of bacteriology, virology and immunity vol 2: Systemic bacteriology, 7th ed. Edward Arnold Ltd: London; 1983. p. 218-45.  Back to cited text no. 9
    
10.
Nayak N, Satpathy G, Vajpayee RB, Pandey RM. A simple alternative method for rapid detection of slime produced by Staphylococcus epidermidis isolates in bacterial keratitis. Indian J Med Res 2001;114:169-72.  Back to cited text no. 10
[PUBMED]    
11.
Archer GL, Karchmer AW, Vishniavsky N, Johnston JL. Plasmid pattern analysis for differentiation of infecting from non-infecting Staphylococcus epidermidis . J Infect Dis 1984;149:913-20.  Back to cited text no. 11
[PUBMED]    
12.
Christensen GD, Simpson WA, Bisno AL, Beachey EH. Adherence of slime-producing strains of Staphylococcus epidermidis to smooth surfaces. Infect Immun 1982;32:318-26.  Back to cited text no. 12
    
13.
Limberg MB. A review of bacterial keratitis and bacterial conjunctivitis. Am J Ophthalmol 1991;112:2S-9S.  Back to cited text no. 13
[PUBMED]    
14.
Mahajan VM. Ulcerative keratitis: An analysis of laboratory data on 674 cases. J Ocul Ther Surg 1985;4:138-41.  Back to cited text no. 14
    
15.
Diaz-Mitoma F, Harding GK, Hoban DJ, Roberts RS, Low DF. Clinical significance of a test for slime production in ventriculo-peritoneal shunt infections caused by coagulase negative Staphylococci. J Infect Dis 1987;156:555-60.  Back to cited text no. 15
    
16.
Pal N, Ayyagari A. Species identification and methicillin resistance of coagulase negative Staphylococci from clinical specimens. Indian J Med Res 1989;89:300-5.  Back to cited text no. 16
[PUBMED]    
17.
Quie PG, Belani KK. Coagulase negative Staphylococcal adherence and persistence. J Infect Dis 1987;156:543-7.  Back to cited text no. 17
[PUBMED]    
18.
Younger JJ, Chrsitensen GD, Bartley DL, Simsons JC, Barett FF. Coagulase negative Staphylococci isolated from cerebrospinal fluid shunts: Importance of slime production, species identification and shunt removal to clinical outcome. J Infect Dis 1987;156:548-54.  Back to cited text no. 18
    
19.
Cree RG, Philips I, Noble WC. Adherence characteristics of coagulase negative Staphylococci isolated from patients with infective endocarditis. J Med Microbiol 1995;43:161-8.  Back to cited text no. 19
    
20.
Peters G, Locci R, Pulveror G. Adherence and growth of coagulase negative Staphylococci on surfaces of intravenous catheters. J Infect Dis 1982;146:479-82.  Back to cited text no. 20
    
21.
Arciola CR, Baldassarri L, Montanaro L. Presence of ICA A and ICA D genes and slime production in a collection of staphylococcal strains from catheter associated infections. J Clin Microbiol 2001;39:2151-6.  Back to cited text no. 21
[PUBMED]  [FULLTEXT]  
22.
Schwarz S, Gregory RD, Werckenthin C, Curnock S, Dyke KG. A novel plasmid from Staphylococcus epidermidis specifying resistance to kanamycin, neomycin and tetracycline. J Med Microbiol 1996;45:57-63.  Back to cited text no. 22
    
23.
Cooksey RC, Baldwin JN. Relatedness of tetracycline resistance plasmids among species of coagulase negative Staphylococci . Antimicrobial Agents Chemother 1985;27:234-8.  Back to cited text no. 23
[PUBMED]  [FULLTEXT]  
24.
Parishi JT, Hecht DW. Plasmid profile in epidemiological studies of infections by Staphylococcus epidermidis . J Infect Dis 1980;141:637-43.  Back to cited text no. 24
    


    Figures

  [Figure - 1], [Figure - 2]
 
 
    Tables

  [Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6]


This article has been cited by
1 Correlation of Staphylococcus Epidermidis Phenotype and Its Corneal Virulence
Armando R. Caballero, Aihua Tang, Michael Bierdeman, Richard O’Callaghan, Mary Marquart
Current Eye Research. 2021; 46(5): 638
[Pubmed] | [DOI]
2 Slime production is essential for the adherence of Staphylococcus epidermidis in implant-related infections
Nayak, N., Satpathy, G., Nag, H.L., Venkatesh, P., Ramakrishnan, S., Nag, T.C., Prasad, S.
Journal of Hospital Infection. 2011; 77(2): 153-156
[Pubmed]
3 Slime production is essential for the adherence of Staphylococcus epidermidis in implant-related infections
Journal of Hospital Infection. 2011; 77(2): 153
[VIEW] | [DOI]
4 Epidemiology and antimicrobial resistance of staphylococci isolated from different infectious diseases
Gad, G.F.M., Abd El-Ghafar, A.E.-G.F., El-Domany, R.A.A., Hashem, Z.S.
Brazilian Journal of Microbiology. 2010; 41(2): 333-344
[Pubmed]
5 Correlation of slime production investigated via three different methods in coagulase-negative staphylococci with crystal violet reaction and antimicrobial resistance
Bozkurt, H., Kurtoglu, M.G., Bayram, Y., Keşli, R., Berktaş, M.
Journal of International Medical Research. 2009; 37(1): 121-128
[Pubmed]
6 Infective keratitis: A challenge to Indian ophthalmologists
Srinivasan, M.
Indian Journal of Ophthalmology. 2007; 55(1): 5-6
[Pubmed]



 

Top
 
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

 
  In this article
Abstract
Materials and Me...
Results
Discussion
Acknowledgement
References
Article Figures
Article Tables

 Article Access Statistics
    Viewed6007    
    Printed139    
    Emailed1    
    PDF Downloaded517    
    Comments [Add]    
    Cited by others 6    

Recommend this journal