Correspondence

Case 42-1994: Mycoplasma Pneumonia and Transverse Myelitis

N Engl J Med 1995; 332:1719-1720June 22, 1995

Article

To the Editor:

In the Pathological Discussion of the case of a 19-year-old man with rapidly progressive lower-extremity weakness and dysesthesias after a respiratory tract infection (Nov. 24 issue),1 Dr. Megan B. Murray makes a diagnosis of Mycoplasma pneumoniae infection on the basis of serologic evidence alone, though she mentions the possibility of finding infection with Borrelia burgdorferi on the basis of both serologic results and the polymerase-chain-reaction (PCR) assay.

Recently, several researchers have used the PCR assay to detect M. pneumoniae gene segments in samples including cerebrospinal fluid. Narita et al.2 reported that they used nested PCR to detect DNA sequences of M. pneumoniae in both cerebrospinal fluid and serum samples from patients with clinically and serologically confirmed infection of the central nervous system with this agent. Therefore, the definite diagnosis of transverse myelitis due to M. pneumoniae infection in Case 42-1994 should rely on evidence from this type of assay.

Although M. pneumoniae is very common and is associated with a wide variety of neurologic manifestations, as in this case, there have been only a few reported cases in which it was successfully cultured from cerebrospinal fluid. We think that the use of PCR, a rapid and sensitive diagnostic approach, should become routine in laboratories throughout the world.

Kouichi Asai, M.D.
Shigeru Ohta, M.D.
Matsue Red Cross Hospital, Matsue 690, Japan

2 References

1. 1

   Case Records of the Massachusetts General Hospital (Case 42-1994). N Engl J Med 1994;331:1437-1444
   Full Text | Web of Science | Medline

2. 2

   Narita M, Matsuzono Y, Togashi T, Kajii N. DNA diagnosis of central nervous system infection by Mycoplasma pneumoniae. Pediatrics 1992;90:250-253
   Web of Science | Medline

To the Editor:

With regard to Dr. Murray's Pathological Discussion, I would like to comment on the serologic diagnosis of M. pneumoniae infection. Serologic tests for mycoplasma infections should no longer be based on complement-fixation assays of samples obtained during the acute and convalescent phases of the illness in which lipid extracts of mycoplasma are used as the antigen substrate. For the past 12 years our laboratory has diagnosed acute mycoplasma infections with an indirect fluorescent-antibody method for class-specific antibodies to M. pneumoniae using whole organisms as the antigen substrate. Test kits are commercially available and have been favorably reviewed in the literature. This procedure is readily available and clinically useful in the acute-phase testing of a serum sample, particularly for patients who have been symptomatic for several days, as is often the case with atypical pneumonia and its complications. The test is relatively inexpensive and can be used by any immunoserologic laboratory skilled in the use of fluorescent microscopical techniques. . . .

John B. Carter, M.D.
Lexington Medical Center, West Columbia, SC 29169

Author/Editor Response

Dr. Murray replies:

To the Editor: Dr. Carter and Drs. Asai and Ohta describe two other diagnostic tests for M. pneumoniae, both of which could result in earlier diagnosis than the complement-fixation assay and thus be more useful clinically. The evaluation of rapid diagnostic tests for M. pneumoniae has been complicated by the absence of a true gold standard with which to identify infection. A study of 3546 patients that compared culture with a serologic method involving complement fixation1 found that culture had a sensitivity of 68 percent and a specificity of 97 percent and that the serologic method had a sensitivity of 90 percent and a specificity of 94 percent.

The final diagnosis in the case described in the clinicopathological conference was based on the results of Western blotting, which used a variety of polypeptides obtained from sonicated organisms. When five commercial tests, including complement-fixation assay and indirect fluorescent-antibody test, were compared with immunoblotting, the sensitivity of all five assays was found to be 100 percent.2 The complement-fixation assay had a specificity of 91.3 percent, and the indirect fluorescent-antibody test one of 87.0 percent. (No confidence intervals were reported.) The complement-fixation assay was also noted to be the cheapest of the available tests.

Drs. Asai and Ohta recommend that a positive PCR of cerebrospinal fluid be required to make the diagnosis of transverse myelitis due to M. pneumoniae. In the case series to which they refer, PCR had a sensitivity of 66.7 percent (four of six cases) in diagnosing neurologic complications of M. pneumoniae, as compared with serologic methods involving microparticle agglutination.3 The specificity of PCR is not known, although a single control specimen with confirmed Haemophilus influenzae meningitis was PCR-negative. Although this case series supports the argument that neurologic disease associated with M. pneumoniae is caused by direct invasion of the central nervous system by the organism, I do not believe it confirms this hypothesis. Indeed, the mechanisms of neurologic complications may be as diverse as the various syndromes that have been described.

Megan Murray, M.D.
Massachusetts General Hospital, Boston, MA 02114

3 References

1. 1

   Kenny GE, Kaiser GG, Cooney MK, Foy HM. Diagnosis of Mycoplasma pneumoniae pneumonia: sensitivities and specificities of serology with lipid antigen and isolation of the organism on soy peptone medium for identification of infections. J Clin Microbiol 1990;28:2087-2093
   Web of Science | Medline

2. 2

   Aubert G, Pozzetto B, Gaudin OG, Hafid J, Mbida AD, Ros A. Evaluation of five commercial tests: complement fixation, microparticle agglutination, indirect immunofluorescence, enzyme-linked immunosorbent assay and latex agglutination, in comparison to immunoblotting for Mycoplasma pneumoniae serology. Ann Biol Clin (Paris) 1992;50:593-597
   Web of Science | Medline

3. 3

   Narita M, Matsuzono Y, Togashi T, Kajii N. DNA diagnosis of central nervous system infection by Mycoplasma pneumoniae. Pediatrics 1992;90:250-253
   Web of Science | Medline

Citing Articles (1)

Citing Articles

1. 1

   Joanna Hsing, Miriam Welgampola, Matthew C. Kiernan. (2007) Reversible myeloradiculopathy due to Mycoplasma pneumoniae. Journal of Clinical Neuroscience 14:1, 61-64
   CrossRef