LETTER TO THE EDITOR
Therapeutic Outcomes of Pyogenic Vertebral Osteomyelitis Requiring Spinal Instrumentation Ki-Ho Park,a Oh-Hyun Cho,b In-Gyu Bae,b
Mi Suk Leea
W
e read with great interest the recent article by Arnold et al. (1) on factors associated with treatment failure in pyogenic vertebral osteomyelitis requiring spinal instrumentation. They reported a treatment failure rate of 23.4% (95% confidence interval [95% CI], 16.0% to 32.9%), considerably higher than the rate of 1.7% (95% CI, 1.0% to 3.0%) presented in a literature review that included 30 previous publications describing 689 cases (2). As pointed out by the authors, the use of a strict case definition precluded noninfectious vertebral diseases requiring the placement of hardware, and it might have been responsible for the higher rate of treatment failure. It is also worth noting that a substantial proportion of the microbiologically diagnosed cases were caused by drug-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) (40.5% [32/79]) and Pseudomonas species (8.9% [7/79]). The treatment failure rate was higher in the cases of MRSA (31.3% [10/32]; P ⫽ 0.11) and Pseudomonas (57.4% [4/7]; P ⫽ 0.03) than in methicillin-susceptible S. aureus (MSSA) cases (13.8% [4/29]). S. aureus is the leading cause of vertebral osteomyelitis, with the majority of cases caused by MSSA (3). A recent literature review that included 14 studies conducted during the past decades found that MRSA was responsible for only 2.6% (25/946) of cases of vertebral osteomyelitis (3). However, MRSA has become a predominant cause of pyogenic vertebral osteomyelitis in recent years (4–6), and recurrence has been reported more frequently for cases involving MRSA than for those involving MSSA (4, 5). In a recent study including 139 cases of S. aureus vertebral osteomyelitis, MRSA was associated with a 4.83fold increased odds of relapse compared with MSSA (4). Although there are limited data on the optimal duration of antibiotic treatment in patients with vertebral osteomyelitis treated by surgery and spinal instrumentation, several authors recommend ⱖ6 weeks of antibiotic therapy (7). Arnold et al. (1) evaluated this issue but did not find a significant association between ⬍6 weeks of antibiotic therapy and treatment failure. Recently, two studies showed that prolonged antibiotic therapy was more beneficial in patients with vertebral osteomyelitis infected with antibiotic-resistant organisms than in those infected with antibiotic-susceptible organisms (4, 8). Park et al. (4) reported that among cases of MRSA vertebral osteomyelitis, the recurrence rates differed according to the duration of antibiotic treatment: 41.7% (4 to 6 weeks), 25.0% (6 to 8 weeks), and 5.6% (ⱖ8 weeks) (P ⫽ 0.007). However, this association was not observed among patients with MSSA vertebral osteomyelitis: 6.7% (⬍6 weeks), 0% (6 to 8 weeks), and 4.9% (ⱖ8 weeks) (P ⬎ 0.99). Similarly, the recurrence rates differed according to the duration of antibiotic treatment in cases of vertebral osteomyelitis caused by quinoloneresistant Gram-negative bacilli (50.0% [4 to 8 weeks] versus 4.5%
November 2014 Volume 58 Number 11
[ⱖ8 weeks]; P ⫽ 0.01), but they did not differ in cases of quinolone-susceptible Gram-negative bacilli (16.7% [4 to 8 weeks] versus 0% [ⱖ8 weeks]; P ⫽ 0.19) (8). In the study by Arnold et al. (1), we wonder whether ⬍6 weeks of antibiotic therapy was associated with treatment failure among subgroups of MRSA and Pseudomonas cases. ACKNOWLEDGMENTS There was no funding source for this study. We declare that we have no conflicts of interest.
REFERENCES 1. Arnold R, Rock C, Croft L, Gilliam BL, Morgan DJ. 2014. Factors associated with treatment failure in vertebral osteomyelitis requiring spinal instrumentation. Antimicrob. Agents Chemother. 58:880 – 884. http://dx .doi.org/10.1128/AAC.01452-13. 2. Rayes M, Colen CB, Bahgat DA, Higashida T, Guthikonda M, Rengachary S, Eltahawy HA. 2010. Safety of instrumentation in patients with spinal infection. J. Neurosurg. Spine 12:647– 659. http://dx.doi.org/10 .3171/2009.12.SPINE09428. 3. Mylona E, Samarkos M, Kakalou E, Fanourgiakis P, Skoutelis A. 2009. Pyogenic vertebral osteomyelitis: a systematic review of clinical characteristics. Semin. Arthritis Rheum. 39:10 –17. http://dx.doi.org/10.1016/j.semarthrit .2008.03.002. 4. Park KH, Chong YP, Kim SH, Lee SO, Choi SH, Lee MS, Jeong JY, Woo JH, Kim YS. 2013. Clinical characteristics and therapeutic outcomes of hematogenous vertebral osteomyelitis caused by methicillin-resistant Staphylococcus aureus. J. Infect. 67:556 –564. http://dx.doi.org/10.1016/j .jinf.2013.07.026. 5. Inoue S, Moriyama T, Horinouchi Y, Tachibana T, Okada F, Maruo K, Yoshiya S. 2013. Comparison of clinical features and outcomes of Staphylococcus aureus vertebral osteomyelitis caused by methicillin-resistant and methicillin-sensitive strains. SpringerPlus 2:283. http://dx.doi.org/10.1186 /2193-1801-2-283. 6. Livorsi DJ, Daver NG, Atmar RL, Shelburne SA, White AC, Jr, Musher DM. 2008. Outcomes of treatment for hematogenous Staphylococcus aureus vertebral osteomyelitis in the MRSA ERA. J. Infect. 57:128 –131. http: //dx.doi.org/10.1016/j.jinf.2008.04.012. 7. Chen WH, Jiang LS, Dai LY. 2007. Surgical treatment of pyogenic vertebral osteomyelitis with spinal instrumentation. Eur. Spine J. 16:1307–1316. http://dx.doi.org/10.1007/s00586-006-0251-4. 8. Park KH, Cho OH, Jung M, Suk KS, Lee JH, Park JS, Ryu KN, Kim SH, Lee SO, Choi SH, Bae IG, Kim YS, Woo JH, Lee MS. 2014. Clinical characteristics and outcomes of hematogenous vertebral osteomyelitis caused by gram-negative bacteria. J. Infect. 69:42–50. http://dx.doi.org/10 .1016/j.jinf.2014.02.009.
Address correspondence to Mi Suk Lee, [email protected]. For the author reply, see doi:10.1128/AAC.04063-14. Copyright © 2014, American Society for Microbiology. All Rights Reserved. doi:10.1128/AAC.03934-14
Antimicrobial Agents and Chemotherapy
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Division of Infectious Diseases, Department of Internal Medicine, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Republic of Koreaa; Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Koreab
Therapeutic Outcomes of Pyogenic Vertebral Osteomyelitis Requiring Spinal Instrumentation Ki-Ho Park,a Oh-Hyun Cho,b In-Gyu Bae,b
Mi Suk Leea
W
e read with great interest the recent article by Arnold et al. (1) on factors associated with treatment failure in pyogenic vertebral osteomyelitis requiring spinal instrumentation. They reported a treatment failure rate of 23.4% (95% confidence interval [95% CI], 16.0% to 32.9%), considerably higher than the rate of 1.7% (95% CI, 1.0% to 3.0%) presented in a literature review that included 30 previous publications describing 689 cases (2). As pointed out by the authors, the use of a strict case definition precluded noninfectious vertebral diseases requiring the placement of hardware, and it might have been responsible for the higher rate of treatment failure. It is also worth noting that a substantial proportion of the microbiologically diagnosed cases were caused by drug-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) (40.5% [32/79]) and Pseudomonas species (8.9% [7/79]). The treatment failure rate was higher in the cases of MRSA (31.3% [10/32]; P ⫽ 0.11) and Pseudomonas (57.4% [4/7]; P ⫽ 0.03) than in methicillin-susceptible S. aureus (MSSA) cases (13.8% [4/29]). S. aureus is the leading cause of vertebral osteomyelitis, with the majority of cases caused by MSSA (3). A recent literature review that included 14 studies conducted during the past decades found that MRSA was responsible for only 2.6% (25/946) of cases of vertebral osteomyelitis (3). However, MRSA has become a predominant cause of pyogenic vertebral osteomyelitis in recent years (4–6), and recurrence has been reported more frequently for cases involving MRSA than for those involving MSSA (4, 5). In a recent study including 139 cases of S. aureus vertebral osteomyelitis, MRSA was associated with a 4.83fold increased odds of relapse compared with MSSA (4). Although there are limited data on the optimal duration of antibiotic treatment in patients with vertebral osteomyelitis treated by surgery and spinal instrumentation, several authors recommend ⱖ6 weeks of antibiotic therapy (7). Arnold et al. (1) evaluated this issue but did not find a significant association between ⬍6 weeks of antibiotic therapy and treatment failure. Recently, two studies showed that prolonged antibiotic therapy was more beneficial in patients with vertebral osteomyelitis infected with antibiotic-resistant organisms than in those infected with antibiotic-susceptible organisms (4, 8). Park et al. (4) reported that among cases of MRSA vertebral osteomyelitis, the recurrence rates differed according to the duration of antibiotic treatment: 41.7% (4 to 6 weeks), 25.0% (6 to 8 weeks), and 5.6% (ⱖ8 weeks) (P ⫽ 0.007). However, this association was not observed among patients with MSSA vertebral osteomyelitis: 6.7% (⬍6 weeks), 0% (6 to 8 weeks), and 4.9% (ⱖ8 weeks) (P ⬎ 0.99). Similarly, the recurrence rates differed according to the duration of antibiotic treatment in cases of vertebral osteomyelitis caused by quinoloneresistant Gram-negative bacilli (50.0% [4 to 8 weeks] versus 4.5%
November 2014 Volume 58 Number 11
[ⱖ8 weeks]; P ⫽ 0.01), but they did not differ in cases of quinolone-susceptible Gram-negative bacilli (16.7% [4 to 8 weeks] versus 0% [ⱖ8 weeks]; P ⫽ 0.19) (8). In the study by Arnold et al. (1), we wonder whether ⬍6 weeks of antibiotic therapy was associated with treatment failure among subgroups of MRSA and Pseudomonas cases. ACKNOWLEDGMENTS There was no funding source for this study. We declare that we have no conflicts of interest.
REFERENCES 1. Arnold R, Rock C, Croft L, Gilliam BL, Morgan DJ. 2014. Factors associated with treatment failure in vertebral osteomyelitis requiring spinal instrumentation. Antimicrob. Agents Chemother. 58:880 – 884. http://dx .doi.org/10.1128/AAC.01452-13. 2. Rayes M, Colen CB, Bahgat DA, Higashida T, Guthikonda M, Rengachary S, Eltahawy HA. 2010. Safety of instrumentation in patients with spinal infection. J. Neurosurg. Spine 12:647– 659. http://dx.doi.org/10 .3171/2009.12.SPINE09428. 3. Mylona E, Samarkos M, Kakalou E, Fanourgiakis P, Skoutelis A. 2009. Pyogenic vertebral osteomyelitis: a systematic review of clinical characteristics. Semin. Arthritis Rheum. 39:10 –17. http://dx.doi.org/10.1016/j.semarthrit .2008.03.002. 4. Park KH, Chong YP, Kim SH, Lee SO, Choi SH, Lee MS, Jeong JY, Woo JH, Kim YS. 2013. Clinical characteristics and therapeutic outcomes of hematogenous vertebral osteomyelitis caused by methicillin-resistant Staphylococcus aureus. J. Infect. 67:556 –564. http://dx.doi.org/10.1016/j .jinf.2013.07.026. 5. Inoue S, Moriyama T, Horinouchi Y, Tachibana T, Okada F, Maruo K, Yoshiya S. 2013. Comparison of clinical features and outcomes of Staphylococcus aureus vertebral osteomyelitis caused by methicillin-resistant and methicillin-sensitive strains. SpringerPlus 2:283. http://dx.doi.org/10.1186 /2193-1801-2-283. 6. Livorsi DJ, Daver NG, Atmar RL, Shelburne SA, White AC, Jr, Musher DM. 2008. Outcomes of treatment for hematogenous Staphylococcus aureus vertebral osteomyelitis in the MRSA ERA. J. Infect. 57:128 –131. http: //dx.doi.org/10.1016/j.jinf.2008.04.012. 7. Chen WH, Jiang LS, Dai LY. 2007. Surgical treatment of pyogenic vertebral osteomyelitis with spinal instrumentation. Eur. Spine J. 16:1307–1316. http://dx.doi.org/10.1007/s00586-006-0251-4. 8. Park KH, Cho OH, Jung M, Suk KS, Lee JH, Park JS, Ryu KN, Kim SH, Lee SO, Choi SH, Bae IG, Kim YS, Woo JH, Lee MS. 2014. Clinical characteristics and outcomes of hematogenous vertebral osteomyelitis caused by gram-negative bacteria. J. Infect. 69:42–50. http://dx.doi.org/10 .1016/j.jinf.2014.02.009.
Address correspondence to Mi Suk Lee, [email protected]. For the author reply, see doi:10.1128/AAC.04063-14. Copyright © 2014, American Society for Microbiology. All Rights Reserved. doi:10.1128/AAC.03934-14
Antimicrobial Agents and Chemotherapy
p. 7021
aac.asm.org
7021
Downloaded from http://aac.asm.org/ on April 9, 2015 by UNIV OF CALIF-SAN FRANCISCO
Division of Infectious Diseases, Department of Internal Medicine, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Republic of Koreaa; Department of Internal Medicine, Gyeongsang National University School of Medicine, Jinju, Republic of Koreab
