TO THE EDITOR:
In our opinion, "Pyogenic Vertebral Osteomyelitis" (79-A: 874—880, June 1997), by Carragee, lacks a complete table of data showing the patient's origin (hospital or other sources), the isolated microorganism, the basic lesion, and any previous invasive procedures or central vascular approaches.
The high prevalence of immunodeficiency (forty-four of 111 patients; 40 per cent) may be responsible for the high prevalence of low-virulence (opportunistic) pathogens in the series. Thus, the acceptance of the article as a whole may lead to a change in the initial therapeutic approach by widening the spectrum to include so-called opportunistic microorganisms that are unlikely to affect the general population.
In our clinical experience, infections caused by opportunistic pathogens are associated with immunodepression and invasive procedures and they must therefore be evaluated in that context.
It would also be of interest to know the rate of mortality and of neurological deficit in relation to the microorganism, since these parameters were only given for Staphylococcus aureus.
Angel M. Hidalgo-Ovejero; Iñaki Otermin; Serafín García-Mata: Avda. Pio XII n° 16 Esc Dcha 3°C, 31008 Pamplona, Spain
Dr. Carragee replies:
I believe that Hidalgo-Ovejero et al. correctly point out the association, shown by my data, between a greater prevalence of infection with low-virulence organisms and impairment of the immune system. As stated in my report, the population that I studied does not represent the patient population in a general community hospital and care should be taken when generalizing the data. However, an immunocompromised or elderly patient who has clinical vertebral osteomyelitis should be considered to have a potential infection with less virulent organisms, regardless of the setting.
Regarding the rate of mortality and of neurological deficit associated with low-virulence organisms, most of the groups were too small for me to give cogent rates for individual organisms.
Finally, the records of all of the patients in this study were retrieved from acute-care hospital-based records; thus, patients who were cared for exclusively as outpatients may have been missed. These patients would likely have been less ill and perhaps would have been empirically treated with an antibiotic without a culture. Again, this may have skewed the data to include a greater proportion of very ill or esoteric cases. However, in my experience, outpatient treatment of a spinal infection is very uncommon.
Eugene J. Carragee, M.D.: Orthopaedic Spine Center, Stanford University School of Medicine, 300 Pasteur Drive, Room R-171, Stanford, California 94305