Effects of Culture Media on Detection of Methicillin Resistance in Staphylococcus Aureus and Coagulase Negative Staphylococci by Disc Diffusion Methods

Overview

Journal J Clin Pathol

Specialty Pathology

Date 1993 May 1

PMID 8320317

Citations 5

Authors

L M Milne

M R Crow

A G Emptage

J B Selkon

Affiliations

Soon will be listed here.

Abstract

Aims: To test 10 culture media for their ability to detect resistance and sensitivity of staphylococci to methicillin by disc diffusion.

Methods: Fifty strains of Staphylococcus aureus and 135 strains of coagulase negative staphylococci were tested using Columbia, Diagnostic Sensitivity Test, Mueller Hinton, Sensitest and Iso-sensitest agars with and without 5% added sodium chloride. Cultures were examined after 18 and 40 hours of incubation. The diameter of the zone and its characteristics were recorded and these media were assessed for their ability to produce clear, readable zones of inhibition. Changes in the variables which determined resistance were investigated. Results were analysed allowing a zone diameter reduction of 8 mm and 10 mm compared with the control in addition to the standard 6 mm.

Results: Columbia agar with added sodium chloride supported the growth of all strains, detected the highest number of resistant strains, and was the easiest to read. Resistance was detected after 18 hours in most resistant strains, but some required 40 hours of incubation. There was poor agreement, however, on this medium (63-94%) between disc diffusion and the reference MIC method for sensitive strains. Allowing a greater reduction in zone size resulted in more agreement with sensitive strains but with consequently lowered detection of resistant strains. The other media showed some growth failures and more zones that were difficult to read. More resistance was detected when incubation was prolonged to 40 hours but this was consistently less than on Columbia agar with added salt.

Conclusions: None of the media detected all of the resistant strains. Columbia agar with added salt was the most satisfactory medium in this respect, but it misidentified up to 37% of the sensitive strains as resistant. Methicillin susceptibility testing by disc diffusion testing is unreliable.

Citing Articles

Comparison of susceptibility testing methods with mecA gene analysis for determining oxacillin (methicillin) resistance in clinical isolates of Staphylococcus aureus and coagulase-negative Staphylococcus spp.

Kohner P, Uhl J, Kolbert C, Persing D, Cockerill 3rd F J Clin Microbiol. 1999; 37(9):2952-61.

PMID: 10449481 PMC: 85421. DOI: 10.1128/JCM.37.9.2952-2961.1999.

Comparison of screening methods to identify methicillin-resistant Staphylococcus aureus.

Kampf G, Weist K, Swidsinski S, Kegel M, Ruden H Eur J Clin Microbiol Infect Dis. 1997; 16(4):301-7.

PMID: 9177964 DOI: 10.1007/BF01695635.

Comparison of disk diffusion, the E test, and detection of mecA for determination of methicillin resistance in coagulase-negative staphylococci.

Mulder J Eur J Clin Microbiol Infect Dis. 1996; 15(7):567-73.

PMID: 8874074 DOI: 10.1007/BF01709365.

Effects of culture media on detection of methicillin resistance in coagulase negative staphylococci.

Scott R, Morgan J, Pether J, Jones J, Richardson J, Bosley R J Clin Pathol. 1994; 47(4):380.

PMID: 8027384 PMC: 501951. DOI: 10.1136/jcp.47.4.380-a.

Activity of the fourth generation cephalosporin FK-037 against methicillin-resistant Staphylococcus aureus under conditions maximizing PBP2' production.

Hamilton-Miller J Eur J Clin Microbiol Infect Dis. 1994; 13(12):1053-5.

PMID: 7889967 DOI: 10.1007/BF02111826.

References

ANNEAR D . The effect of temperature on resistance of Staphylococcus aureus to methicillin and some other antibioics. Med J Aust. 1968; 1(11):444-6. View

Barber M . NATURALLY OCCURING METHICILLIN-RESISTANT STAPHYLOCOCCI. J Gen Microbiol. 1964; 35:183-90. DOI: 10.1099/00221287-35-2-183. View

Churcher G . A screening test for the detection of methicillin-resistant staphylococci. J Clin Pathol. 1968; 21(2):213-7. PMC: 473740. DOI: 10.1136/jcp.21.2.213. View

Hewitt J, COE A, PARKER M . The detection of methicillin resistance in Staphylococcus aureus. J Med Microbiol. 1969; 2(4):443-56. DOI: 10.1099/00222615-2-4-443. View

Brown D, Kothari D . The reliability of methicillin sensitivity tests on four culture media. J Clin Pathol. 1974; 27(5):420-6. PMC: 478140. DOI: 10.1136/jcp.27.5.420. View

Richardson J, MARPLES R . Differences in antibiotic susceptibility between Staphylococcus epidermidis and Staphylococcus saprophyticus. J Antimicrob Chemother. 1980; 6(4):499-510. DOI: 10.1093/jac/6.4.499. View

Hamilton-Miller J, Iliffe A . Antimicrobial resistance in coagulase-negative staphylococci. J Med Microbiol. 1985; 19(2):217-26. DOI: 10.1099/00222615-19-2-217. View

Libert J, Colas des Francs D . [Sensitivity to cephalosporins of coagulase-negative methicillin-resistant staphylococci. In vitro studies by different methods]. Pathol Biol (Paris). 1985; 33(8):831-5. View

Coudron P, Jones D, Dalton H, Archer G . Evaluation of laboratory tests for detection of methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis. J Clin Microbiol. 1986; 24(5):764-9. PMC: 269025. DOI: 10.1128/jcm.24.5.764-769.1986. View

10.

Brown D, Yates V . Methicillin susceptibility testing of Staphylococcus aureus on media containing five percent sodium chloride. Eur J Clin Microbiol. 1986; 5(6):726-8. DOI: 10.1007/BF02013313. View

11.

McAllister T, Mocan H, MURPHY A, Beattie T . Antibiotic susceptibility of staphylococci from CAPD peritonitis in children. J Antimicrob Chemother. 1987; 19(1):95-100. DOI: 10.1093/jac/19.1.95. View

12.

French G, Ling J, Hui Y, Oo H . Determination of methicillin-resistance in Staphylococcus aureus by agar dilution and disc diffusion methods. J Antimicrob Chemother. 1987; 20(4):599-608. DOI: 10.1093/jac/20.4.599. View

13.

Milne L, CURTIS G, Crow M, Kraak W, Selkon J . Comparison of culture media for detecting methicillin resistance in Staphylococcus aureus and coagulase negative staphylococci. J Clin Pathol. 1987; 40(10):1178-81. PMC: 1141190. DOI: 10.1136/jcp.40.10.1178. View

14.

Cheng A, French G . Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong. J Hosp Infect. 1988; 12(2):91-101. DOI: 10.1016/0195-6701(88)90131-4. View

15.

JOLLY J, Goldberg M . Methicillin resistance in staphylococci: an evaluation of conditions for detection. Med Lab Sci. 1989; 46(1):2-5. View

16.

Mouton R, Mulders S, de Knijff J, Hermans J . Comparison of test systems for recognition of methicillin resistance in Staphylococcus aureus. Eur J Clin Microbiol Infect Dis. 1989; 8(11):968-73. DOI: 10.1007/BF01967567. View

17.

Hedin G, Hambraeus A . Screening tests for the detection of methicillin resistance in Staphylococcus epidermidis. J Antimicrob Chemother. 1991; 28(5):681-94. DOI: 10.1093/jac/28.5.681. View

18.

Sutherland R, Rolinson G . CHARACTERISTICS OF METHICILLIN-RESISTANT STAPHYLOCOCCI. J Bacteriol. 1964; 87:887-99. PMC: 277108. DOI: 10.1128/jb.87.4.887-899.1964. View