mycoplasma pneumoniae is an important cause of respiratory tract infections including community - acquired pneumonia .
it has been suggested that the pathogen may also play a role in the development of atherosclerosis .
this hypothesis is supported by the ability of m. pneumoniae to cause extrapulmonary manifestations affecting the blood vessels , , .
however , others have presented discordant results , so that the role of m. pneumoniae in the pathogenesis of atherosclerosis must still be regarded as unknown , .
serum iga antibodies are a more reliable indicator for acute m. pneumoniae infection than igm , because specific igm are not mounted regularly in elderly patients , .
importantly , the serum level of specific iga declines to normal values earlier after acute infection than the level of specific igm , with a significant decrease 60 days after the onset of disease .
the aim of this study was to investigate the role of m. pneumoniae in the development atherosclerosis by repeated testing of specific iga over a period of 6 month .
ninety - one consecutive patients with symptomatic and asymptomatic internal carotid artery ( ica ) stenosis > 70% , who were admitted for surgery march and july 2004 were enrolled in this study .
thirty - nine patients ( 43% ) had asymptomatic ica stenosis , 32 patients ( 35% ) had transient ischaemic episodes and 20 patients ( 22% ) were operated on for non - disabling stroke .
all patients were planned for routine eversion endarterectomy ( eea ) of the ica under regional anaesthesia .
as anaesthetic agent 1% lidocaine was used for a combined superficial and deep cervical block .
symptomatic patients with stroke had an interval of less than 6 weeks prior to surgery ; symptomatic patients with transient hemispheric and non - hemispheric symptoms were all operated on within 3 weeks after presentation . for all patients , the following data were assessed : age , sex , clinical stage of carotid artery disease ( cad ) ( right / left ) , degree of stenosis ( right / left ) , body mass index ( bmi ) , alcohol consumption ( gram / week ) , nicotine ( cigarettes / day ) , diabetes mellitus , cholesterol , triglycerides and homocysteine .
patients on antihypertensive medication or a blood pressure of 140/75 mmhg on repeat measurements were characterized hypertensive .
maximum ica stenosis was assessed by magnetic resonance angiography and duplex and stenosis of 70% were an indication for surgery .
serum was obtained by venipuncture of the antecubital vein using standard tubes ( vacuette edta tubes , greiner bio - one , kremsmuenster , austria ) and centrifugation 10 minutes at 2,000 g. serum was stored at 80c until use . the first serum specimen ( s1 )
was taken before surgery , and the second after an interval of 6 months ( s2 ) .
specific iga were measured by the seromp iga kit ( savyon diagnostics , ashdod , israel ) according to the manufacturer s recommendations . as indicated by the manufacturer values > 20 bu ( binding units ) were considered positive .
statistical analysis was performed by chi squared test ( yates correction ) , using epiinfo 2002 ( cdc , atlanta , ga , usa )
the iga seroprevalence at admission ( s1 ) was 18.7% ( 17 of 91 patients ) . in these patients ,
pneumoniae iga after a period of 6 month ( median : 36 bu ; range : 2257 bu ) . among the 74 patients with negative s1 results ,
the elisa results and basic clinical data of the 18 patients with 1 result > 20 bu are shown by table 1 ( tab .
none of the assessed demographic factors or risk factors for atherosclerosis was associated with iga seropositivity , neither were the degree cavk or the degree of stenosis .
in this study we found a considerable seroprevalence of iga antibodies to m. pneumoniae in patients with internal carotid artery stenosis .
however , the more remarkable finding was that in the majority of our patients iga remained elevated at essentially constant levels through a period of at least 6 month .
in contrast , few patients ( 3 ) developed specific iga between the taking of the first and the second serum specimen .
we have focused on iga determination in the present study , because specific igm formation may be lacking in the elderly .
igg antibodies , on the other hand , remain elevated for longtime after infection , which results in a high igg seroprevalence , that can cause interpretation difficulties .
determination of specific iga is a suitable tool for the diagnosis of m. pneumoniae infection .
it has been shown that after infection specific iga decline to normal values ( i.e. levels below the cut - off value of commercially available tests ) earlier than specific igm .
however , iga - based diagnosis is less established than igm- or igg - based diagnosis , and persistently elevated iga as indicator of chronic infection , although biologically plausible , has to be interpreted with caution .
it has to be mentioned that differing figures concerning the seroprevalence of iga antibodies to m. pneumoniae in elderly patients have been published , with seroprevalences up to 79% , .
however , the applied assay and the respective cut - off level for positivity is obviously important in this context . by the assay applied in the present study ,
we have found a seroprevalence of 13% ( > 20 bu ) and no value > 30 bu among 46 healthy subjects .
nevertheless , a significant trend to a decrease in antibody level would be expected if the elevated iga levels in our patients should simply reflect past respiratory tract infection .
it is notable that in the 13 patients with persistently high iga levels , 6 showed an increasing and 6 a decreasing iga level , with the level in one patient remaining constant ( table 1 ( tab .
an important study negotiating a potential role of m. pneumoniae in the development of atherosclerosis has been provided by maraha et al . , who failed to detect the pathogen in the great majority of 103 atherectomy specimens and degenerative heart valve specimens .
however , it should be considered that some mycoplasma - associated diseases , including severe pneumonia and neurological manifestations , are immunologically mediated and require the presence of the pathogen only in an early stage of the disease , , .
therefore , serological methods may be advantageous to explore the association between m. pneumoniae infection and atherosclerosis . in conclusion ,
we have applied a new serological approach to investigate the role of m. pneumoniae in the development of atherosclerosis .
the results can not be explained throughout by the general seroprevalence , or by past respiratory tract infections with the pathogen , so that they suggest a role for m. pneumoniae in the development of atherosclerosis .
however , it has to be considered that the association between chronic mycoplasma infection and persistently elevated iga antibodies is not yet proven by large - scale epidemiological investigations .
future studies on the potential role of m. pneumoniae in the development of atherosclerosis are warranted .
 background : it has been suggested that mycoplasma pneumoniae may play a role in the development of atherosclerosis , but to date this association is still a matter of debate due to conflicting findings.methods : we have investigated the levels of specific iga antibodies to m. pneumoniae in 91 patients with internal carotid artery ( ica ) stenosis using a commercial kit ( seromp iga ; savyon diagnostics , israel ; cut - off value : 20 binding units ; bu ) . all patients underwent surgery for ica stenosis . from each patient , the first serum sample ( s1 ) was taken before surgery , and the second after an interval of 6 month ( s2).results : the s1 seroprevalence was 18.7% ( 17/91 ) . 
 thirteen of the 17 patients with positive s1 levels also remained positive after six month , whereby no decrease of iga level was seen ( median s1 level : 34 bu , range : 2265 bu ; median s2 level : 37 bu , range : 2258 bu ) . 
 specifically , six of the patients showed an increased level after 6 months , and six a decrease , with the level remaining constant in one patient . 
 in contrast , only 3 of the 74 s1 negative patients became positive for anti - m . 
 pneumoniae iga between the taking of the first and the second serum specimen ( p<0.01 ) . 
 none of the assessed demographic factors or risk factors for atherosclerosis was associated with iga seropositivity , neither were the degree cavk or the degree of stenosis.conclusion : these findings can not be explained throughout by the general seroprevalence , or by past respiratory tract infections with the pathogen , and therefore may suggest a role for m. pneumoniae in the development of atherosclerosis , since a chronic infection must be assumed . 
Introduction
Material and methods
Results
Discussion
Notes
Conflicts of interest