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Antimicrobial activity of daptomycin against Staphylococcus aureus isolates from skin and skin structure infections of trauma patients
Letter to the Editor
195
T.E. Busch-Westbroek Department of Rehabilitation, Academic Medical Center University of Amsterdam, 1100 DD Amsterdam, The Netherlands C.H.M. van Schie Department of Rehabilitation, Academic Medical Center University of Amsterdam, The Netherlands S.E. Geerlings J.H. DeVries Department of Internal Medicine, Academic Medical Center University of Amsterdam, 1100 DD Amsterdam, The Netherlands 29 May 2010 Available online 9 June 2010 ª 2010 The British Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinf.2010.05.006
Antimicrobial activity of daptomycin against Staphylococcus aureus isolates from skin and skin structure infections of trauma patients
To the editor The new modalities for treatment of skin and soft tissue and surgical site infections due to MDR Gram- positive bacteria, particularly Methicillin resistant Staphylococcus aureus (MRSA) has been addressed in your journal by StevensDL1 and Eliopoulos GM.2 MRSAskin and skin structure infections (SSTIs) in the trauma patients is a growing and difficult clinical problem.3Availability of limited number of antimicrobials effective against MRSA as well as their side effects further limits therapeutic options in the critically ill trauma patients. Daptomycin is a cyclic lipopeptide, which has been recently approved by the U.S. Food and Drug Administration (FDA) for the treatment of complicated skin and skin structure infections (cSSTIs).4 We aimed to evaluate the in vitro activity of this drug against a contemporary collection of consecutive S. aureus isolates from clinically documented SSTIs of admitted trauma patients at level I trauma centre of India.5 All S. aureus isolates were identified by standard biochemical tests5 as well as by the Vitek 2 system using IDGP cards.6 The sensitivity profile of S. aureus isolates to selected comparator antimicrobials, e.g., gentamicin (30 mg), levofloxacin (5 mg), moxifloxacin (5 mg), erythromycin (15 mg), clindamycin (2 mg), rifampicin (5 mg), tetracycline (30 mg), vancomycin (30 mg), teicoplanin (30 mg), and linezolid (30 mg) (BBL TM BD, USA) were tested by the disc diffusion method according to the Clinical And Laboratory Standards Institute (CLSI) guidelines.7 Antimicrobial sensitivity testing was also performed by the VITEK 2 advanced expert system (BioMe ´rieux, Hazelwood, France) using AST GP- 61 cards.6 Methicillin resistance was determined in S. aureus
isolates by using oxacillin (1 mg) disc and cefoxitin (30 mg) disc methods as recommended by the CLSI.7 The S. aureus ATCC 25923 and 43 300 strains were used as controls.7 Vancomycin MICs were determined by Vitek 2 and E-test, performed according to the manufacturers instructions (AB Biodisk, Solna, Sweden). The daptomycin sensitivity of 124 consecutive, nonduplicate S. aureus isolates [72, (72/124, 58%, MRSA, 52, 52/124, 42% MSSA) was evaluated by E-test on Mueller- Hinton agar. The activity of daptomycin is dependent on physiologic levels of calcium.8 Daptomycin, E-test strips, which are FDA cleared contain a constant calcium concentration (40 mg/L) throughout the strip to try to account for the variability of the calcium concentration noted in the MuellerHinton agar media. Susceptibility test results generated by the E-test method are reproducible and have been demonstrated to be equivalent to CLSI reference broth dilution methods, with essential agreement of 97.3% when testing Staphylococci.9 The testing, incubation and MIC interpretation was performed according to manufacturer’s instructions.10 A daptomycin- susceptible breakpoint of 1 mg ml was used for S. aureus as approved by CLSI.11 The antimicrobial resistance in S. aureus isolates is shown in Table 1. All strains were susceptible to Daptomycin, vancomycin, teicoplanin, linezolid, quinopristin/dalfopristin although increases in vancomycin minimum inhibitory concentration (MIC) within the susceptible range (shift in vancomycin MICs from 1 to 2 mg ml, so-called MIC creep) was noted in 13 (13/72,18%) MRSA isolates. Daptomycin MIC results ranged from 0.032 to 0.75 mg/ml amongst both MRSA and MSSA. Methicillin resistance did not adversely affect daptomycin activity against S. aureus. The finding of our study supports previous Indian studies regarding Daptomycin.12,13 A recent study from our hospital, which evaluated daptomycin susceptibility profile of 432 clinical strains of S. aureus from SSTIs of hospitalized patients admitted to various specialties (excluding trauma patients) reported 100% susceptibility against S. aureus.12 The SENTRY Antimicrobial Surveillance programme (2006e2007), which evaluated daptomycin susceptibility profile of 741 S aureus isolates from 14 medical centres across India, had reported only one isolate each of MRSA and MSSA with slightly elevated daptomycin MIC values (2 mg ml).13 There is no question that the number of MRSA infections has increased in our trauma service over the years (Under Publication). Our findings suggest that
Table 1 Antimicrobial resistances in isolates of Staphylococcus aureus. Antibiotics
MRSAa (n Z 72) n (%) MSSAb (n Z 52) n (%)
Gentamicin Levofloxacin Moxifloxacin Erythromycin Clindamycin Rifampicin Tetracycline
60 70 71 55 28 16 37
a b
(83.33%) (97.22%) (98.61%) (76.39%) (38.89%) (22.22%) (51.39%)
MRSA: Methicillin resistant S aureus. MSSA: Methicillin sensitive S aureus.
8 36 36 12 6 4 4
(15.38%) (69.38%) (69.38%) (23.08%) (11.54%) (7.69%) (7.69%)
196 Daptomycin is a viable alternative to other class comparator agents for the treatment of MRSA cSSTIs. However, clinical outcome studies in our settings are required to justify its use in parenteral antibiotic programme.
References 1. Stevens DL. Treatment of skin and soft tissue and surgical site infections due to MDR gram-positive bacteria. J Infect 2009;59 (Suppl. 1):S32e9. 2. Eliopoulos GM. Microbiology of drugs for treating multiply drugresistant gram-positive bacteria. J Infect 2009;59(Suppl. 1): S17e24. 3. Cook A, Berne J, Norwood S. The incidence and complications of Methicillin resistant Staphylococcus aureus at a community level I trauma Center. J Trauma 2009;67:102e7. 4. Carpenter CF, Chambers HF. Daptomycin: another novel agent for treating infections due to drug-resistant gram-positive pathogens. Clin Infect Dis 2004;38:994e1000. 5. Baird D. Staphylococcus: cluster-forming gram-positive cocci. In: Mackie & Mc Cartney practical medical microbiology. 14th ed. Collee AG, Fraser BP, Marmion JG, Simmons A, Eds. New York: Churchill LivingStone, pp.245e261. 6. Nakasone I, Kinjo T, Yamane N, Kisanuki K, Shiohira CM. Laboratory-based evaluation of the colorimetric VITEK-2 Compact system for species identification and of the advanced expert system for detection of antimicrobial resistances: VITEK-2 Compact system identification and antimicrobial susceptibility testing. Diagn Microbiol Infect Dis 2007;58:191e8. 7. Clinical and Laboratory standards institute (CLSI). Performance standards for antimicrobial susceptibility testing, 16th informational supplements. Wayne PA: CLSI; 2006. 8. Fuchs PC, Barry AL, Brown SD. Daptomycin susceptibility tests: interpretive criteria, quality control, and effect of calcium on in vitro tests. Diagn Microbiol Infect Dis 2000;38:51e8. 9. Jorgensen JH, Crawford SA. Assessment of two commercial susceptibility test methods for determination of daptomycin MICs. J Clin Microbiol 2006;44:2126e9. 10. Etest Customer Information Sheet 014. Etest DaptomycinR DPCtechnical variables that may cause discrepancies in MIC testing.
Letters to the Editor Available at, http://abbiodisk.com/pdf/cis/M0000601.pdf [accessed 21.05.10]. 11. Clinical and Laboratory standards institute (CLSI). Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard-seventeenth edition, M7eA7. Wayne PA: CLSI; 2006. 12. Dhawan B, Gadepalli R, Kapil A. In vitro activity of daptomycin against Staphylococcus aureus and vancomycin-resistant Enterococcus faecium isolates associated with skin and soft tissue infections: first results from India. Diagn Microbiol Infect Dis 2009;65:196e8. 13. Mathai D, Biedenbach DJ, Jones RN, Bell JM, Turnidge J, Sader HS. India daptomycin study group. Activity of daptomycin against gram-positive bacterial isolates from Indian medical centres (2006e2007). Int J Antimicrob Agents 2009;34:497e9.
Bijayini Behera Neetu Jain Satyapriya Sharma Purva Mathur* Department of Laboratory Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi 110029, India *Corresponding author. Tel.: þ91 11 9810303507. E-mail address: [email protected] (P. Mathur) Mahesh C. Misra Department of Surgical Disciplines, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi 110029, India 7 June 2010 Available online 12 June 2010 ª 2010 The British Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinf.2010.06.003
195
T.E. Busch-Westbroek Department of Rehabilitation, Academic Medical Center University of Amsterdam, 1100 DD Amsterdam, The Netherlands C.H.M. van Schie Department of Rehabilitation, Academic Medical Center University of Amsterdam, The Netherlands S.E. Geerlings J.H. DeVries Department of Internal Medicine, Academic Medical Center University of Amsterdam, 1100 DD Amsterdam, The Netherlands 29 May 2010 Available online 9 June 2010 ª 2010 The British Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinf.2010.05.006
Antimicrobial activity of daptomycin against Staphylococcus aureus isolates from skin and skin structure infections of trauma patients
To the editor The new modalities for treatment of skin and soft tissue and surgical site infections due to MDR Gram- positive bacteria, particularly Methicillin resistant Staphylococcus aureus (MRSA) has been addressed in your journal by StevensDL1 and Eliopoulos GM.2 MRSAskin and skin structure infections (SSTIs) in the trauma patients is a growing and difficult clinical problem.3Availability of limited number of antimicrobials effective against MRSA as well as their side effects further limits therapeutic options in the critically ill trauma patients. Daptomycin is a cyclic lipopeptide, which has been recently approved by the U.S. Food and Drug Administration (FDA) for the treatment of complicated skin and skin structure infections (cSSTIs).4 We aimed to evaluate the in vitro activity of this drug against a contemporary collection of consecutive S. aureus isolates from clinically documented SSTIs of admitted trauma patients at level I trauma centre of India.5 All S. aureus isolates were identified by standard biochemical tests5 as well as by the Vitek 2 system using IDGP cards.6 The sensitivity profile of S. aureus isolates to selected comparator antimicrobials, e.g., gentamicin (30 mg), levofloxacin (5 mg), moxifloxacin (5 mg), erythromycin (15 mg), clindamycin (2 mg), rifampicin (5 mg), tetracycline (30 mg), vancomycin (30 mg), teicoplanin (30 mg), and linezolid (30 mg) (BBL TM BD, USA) were tested by the disc diffusion method according to the Clinical And Laboratory Standards Institute (CLSI) guidelines.7 Antimicrobial sensitivity testing was also performed by the VITEK 2 advanced expert system (BioMe ´rieux, Hazelwood, France) using AST GP- 61 cards.6 Methicillin resistance was determined in S. aureus
isolates by using oxacillin (1 mg) disc and cefoxitin (30 mg) disc methods as recommended by the CLSI.7 The S. aureus ATCC 25923 and 43 300 strains were used as controls.7 Vancomycin MICs were determined by Vitek 2 and E-test, performed according to the manufacturers instructions (AB Biodisk, Solna, Sweden). The daptomycin sensitivity of 124 consecutive, nonduplicate S. aureus isolates [72, (72/124, 58%, MRSA, 52, 52/124, 42% MSSA) was evaluated by E-test on Mueller- Hinton agar. The activity of daptomycin is dependent on physiologic levels of calcium.8 Daptomycin, E-test strips, which are FDA cleared contain a constant calcium concentration (40 mg/L) throughout the strip to try to account for the variability of the calcium concentration noted in the MuellerHinton agar media. Susceptibility test results generated by the E-test method are reproducible and have been demonstrated to be equivalent to CLSI reference broth dilution methods, with essential agreement of 97.3% when testing Staphylococci.9 The testing, incubation and MIC interpretation was performed according to manufacturer’s instructions.10 A daptomycin- susceptible breakpoint of 1 mg ml was used for S. aureus as approved by CLSI.11 The antimicrobial resistance in S. aureus isolates is shown in Table 1. All strains were susceptible to Daptomycin, vancomycin, teicoplanin, linezolid, quinopristin/dalfopristin although increases in vancomycin minimum inhibitory concentration (MIC) within the susceptible range (shift in vancomycin MICs from 1 to 2 mg ml, so-called MIC creep) was noted in 13 (13/72,18%) MRSA isolates. Daptomycin MIC results ranged from 0.032 to 0.75 mg/ml amongst both MRSA and MSSA. Methicillin resistance did not adversely affect daptomycin activity against S. aureus. The finding of our study supports previous Indian studies regarding Daptomycin.12,13 A recent study from our hospital, which evaluated daptomycin susceptibility profile of 432 clinical strains of S. aureus from SSTIs of hospitalized patients admitted to various specialties (excluding trauma patients) reported 100% susceptibility against S. aureus.12 The SENTRY Antimicrobial Surveillance programme (2006e2007), which evaluated daptomycin susceptibility profile of 741 S aureus isolates from 14 medical centres across India, had reported only one isolate each of MRSA and MSSA with slightly elevated daptomycin MIC values (2 mg ml).13 There is no question that the number of MRSA infections has increased in our trauma service over the years (Under Publication). Our findings suggest that
Table 1 Antimicrobial resistances in isolates of Staphylococcus aureus. Antibiotics
MRSAa (n Z 72) n (%) MSSAb (n Z 52) n (%)
Gentamicin Levofloxacin Moxifloxacin Erythromycin Clindamycin Rifampicin Tetracycline
60 70 71 55 28 16 37
a b
(83.33%) (97.22%) (98.61%) (76.39%) (38.89%) (22.22%) (51.39%)
MRSA: Methicillin resistant S aureus. MSSA: Methicillin sensitive S aureus.
8 36 36 12 6 4 4
(15.38%) (69.38%) (69.38%) (23.08%) (11.54%) (7.69%) (7.69%)
196 Daptomycin is a viable alternative to other class comparator agents for the treatment of MRSA cSSTIs. However, clinical outcome studies in our settings are required to justify its use in parenteral antibiotic programme.
References 1. Stevens DL. Treatment of skin and soft tissue and surgical site infections due to MDR gram-positive bacteria. J Infect 2009;59 (Suppl. 1):S32e9. 2. Eliopoulos GM. Microbiology of drugs for treating multiply drugresistant gram-positive bacteria. J Infect 2009;59(Suppl. 1): S17e24. 3. Cook A, Berne J, Norwood S. The incidence and complications of Methicillin resistant Staphylococcus aureus at a community level I trauma Center. J Trauma 2009;67:102e7. 4. Carpenter CF, Chambers HF. Daptomycin: another novel agent for treating infections due to drug-resistant gram-positive pathogens. Clin Infect Dis 2004;38:994e1000. 5. Baird D. Staphylococcus: cluster-forming gram-positive cocci. In: Mackie & Mc Cartney practical medical microbiology. 14th ed. Collee AG, Fraser BP, Marmion JG, Simmons A, Eds. New York: Churchill LivingStone, pp.245e261. 6. Nakasone I, Kinjo T, Yamane N, Kisanuki K, Shiohira CM. Laboratory-based evaluation of the colorimetric VITEK-2 Compact system for species identification and of the advanced expert system for detection of antimicrobial resistances: VITEK-2 Compact system identification and antimicrobial susceptibility testing. Diagn Microbiol Infect Dis 2007;58:191e8. 7. Clinical and Laboratory standards institute (CLSI). Performance standards for antimicrobial susceptibility testing, 16th informational supplements. Wayne PA: CLSI; 2006. 8. Fuchs PC, Barry AL, Brown SD. Daptomycin susceptibility tests: interpretive criteria, quality control, and effect of calcium on in vitro tests. Diagn Microbiol Infect Dis 2000;38:51e8. 9. Jorgensen JH, Crawford SA. Assessment of two commercial susceptibility test methods for determination of daptomycin MICs. J Clin Microbiol 2006;44:2126e9. 10. Etest Customer Information Sheet 014. Etest DaptomycinR DPCtechnical variables that may cause discrepancies in MIC testing.
Letters to the Editor Available at, http://abbiodisk.com/pdf/cis/M0000601.pdf [accessed 21.05.10]. 11. Clinical and Laboratory standards institute (CLSI). Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically; approved standard-seventeenth edition, M7eA7. Wayne PA: CLSI; 2006. 12. Dhawan B, Gadepalli R, Kapil A. In vitro activity of daptomycin against Staphylococcus aureus and vancomycin-resistant Enterococcus faecium isolates associated with skin and soft tissue infections: first results from India. Diagn Microbiol Infect Dis 2009;65:196e8. 13. Mathai D, Biedenbach DJ, Jones RN, Bell JM, Turnidge J, Sader HS. India daptomycin study group. Activity of daptomycin against gram-positive bacterial isolates from Indian medical centres (2006e2007). Int J Antimicrob Agents 2009;34:497e9.
Bijayini Behera Neetu Jain Satyapriya Sharma Purva Mathur* Department of Laboratory Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi 110029, India *Corresponding author. Tel.: þ91 11 9810303507. E-mail address: [email protected] (P. Mathur) Mahesh C. Misra Department of Surgical Disciplines, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi 110029, India 7 June 2010 Available online 12 June 2010 ª 2010 The British Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jinf.2010.06.003