550
regulated to achieve a left ventricular pressure of 80-100% compared with systemic pressure; such obstruction of the pulmonary flow was clinically well tolerated by the child and no further variation of the balloon size was necessary. The position of the balloon was controlled by echocardiography and radiography. Left ventricular wall thickness increased by 50% in the first 24 h of the procedure and then stabilised. Oxygen saturation did not decrease during preparation despite breathing room air. Inotropic support for the first 2 days was reduced and discontinued at the end of the 3rd day. During the subsequent 24 h the child maintained normal left ventricular cavity dimensions and ejection fraction. The increased wall thickness was also maintained without further inotropic support. The mean pressure ratio between left ventricle and systemic pressure during the preparation period was 87-5% (observations were taken every 2 h). An arterial switch was done on the 5th day. The catheters were removed during surgery. No thromboembolic or septic complications occurred and the pulmonary (neoaortic) and mitral valves were normal at inspection. The postoperative course was complicated by bronchopneumonia and myocardial ischaemia with transient ST elevation in inferior and anterolateral leads without evidence of myocardial infarction in the electrocardiograms at discharge. Serial postoperative echocardiograms showed normal ejection fraction and no regional wall-motion abnormalities. There was no further increase in left ventricular wall thickness after surgery. The patient was extubated on the 15th postoperative day and is in excellent physical condition. This technique could be used for preparation of the left ventricle in patients with transposition of the great arteries with intact ventricular septum who did not undergo neonatal repair. In these patients, the adjustability of the grade of obstruction allows preparation of the left ventricle without an aortopulmonary shunt. Patients who have had an atrial repair, such as the Mustard or Senning operation, but whose right ventricle is failing, could also be prepared for arterial switch. A third application could be as an alternative to pulmonary artery banding in critically ill children with complex congenital heart disease. Departments of Cardiology and Cardiac Surgery, Ospedali Riuniti di Bergamo, 24100 Bergamo, Italy; Department of Paediatric Cardiology, Guy’s Hospital, London
they pack gauzes to be autoclaved. The table becomes covered with glove powder. In autotransfusion larger clots are often filtered out through several thicknesses of gauze. A test revealed that this powder easily passed the filter in a blood administration set. I injected rabbits intravenously with an appropriate amount of glove powder (maize starch) suspended in Ringer’s lactate. The result was either no effect or an acute seizure, followed by what appeared as a death caused by a deepening coma within 30 min. There was no foam on the mouth, and cyanosis was difficult to observe. The rabbit’s lungs looked normal to me macroscopically. After consideration and communication with experienced colleagues, I decided to resume autotransfusion in 1991. This is because our hospital trains district doctors who need to be familiar with the technique for use in remote areas. The probable reduction in immunocompetence caused by the transfusion of donor blood3,4 in patients with an HIV infection rate of 30-40% was also a factor. Reclaimed blood is now either filtered through factory-packed new gauzes or a siphon is used to fill the bag.2 No problems have been encountered since. I feel that the glove-powder particles blocked small pulmonary vessels and that the subsequent white blood cell reaction to these foreign bodies must have been responsible for the symptoms of congestive cardiac failure. Obstetrics and Gynaecology Department, United Bulawayo Hospitals, Bulawayo, Zimbabwe 1. Stewart DB. Extra-uterine pregnancy. In: Lawson
JB, Stewart DB, eds. Obstetrics and gynaecology in the tropics and developing countries. London: Edward Arnold, 1967. 375-77. 2. Verkuyl DAA. How I do it: autotransfusion. Med Dig 1990; 16: 115-20. 3. George CD, Morello PJ. Immunologic effect of blood transfusion upon renal transplantation, tumour operations, and bacterial infections. Rev Am J Surg 1986; 152: 329-37 4. Vyas GN. Guest editorial: symposium on transfusion-associated infections and immune response. Transfusion Med Rev 1988; 2: 193-95
Larva
migrans syndrome: toxocara, ascaris, or
PHILIP BONHOEFFER MARIO CARMINATI LUCIO PARENZAN MICHAEL TYNAN
Giglia TM, Sanders SP, et al. Rapid two stage arterial switch for transpostion of the great arteries and intact ventricular septum beyond the neonatal period. Circulation 1989; 80 (suppl I): 203-08. 2. Bonhoeffer Ph, Henry GW, Katayama H, Kresky R, Carminati M, Parenzan L. Preparation of the "pulmonary ventricle" for arterial switch by adjustable intravascular balloon outflow obstruction: an experimental approach in a lamb model. Cardiol Young 1992; 2: 85-88. 1. Jonas RA,
Glove powder introduced in the circulation by autotransfusion and severe cardiac failure SIR,-Since I started working in Africa in 1976,have tried to autotransfusion when possible.1,2 I saw no complications in more than two hundred procedures, apart from some pink colour of urine caused by haemolysis. Twice I saw mild overloading due to use
excessive use of clear fluids in addition to the autotransfusion. But, in 1990, I saw2 patients who died of heart failure after autotransfusion. The autotransfusion programme was suspended. The citrate used for autotransfusion, for economic reasons bottled and sterilised by our blood bank rather than using citrate from disposable collection units, was checked for microorganisms and for toxins on cell cultures, and found free of impurities. I decided to start autotransfusions again. But a girl of 16, admitted with an ectopic pregnancy, had autotransfusion and died of cardiac failure. The autotransfusion programme was again suspended. I speculated that patients with ectopic pregnancies were more likely to be HIV positive and hence more likely to have an infective myocarditis, but this patient was HIV negative. A few months later, I noticed during an operation white dust falling out of abdominal gauzes. During quiet night duties, nursing sisters often repacked surgical gloves on the same table as where
DOUWE A. A. VERKUYL
both?
SiR,—Visceral larva migrans caused by nematode larvae is an increasingly recognised syndrome in man in large parts of the developed world, despite the assumption that most infections go without symptoms. If clinical manifestation occurs, a wide variety of non-specific symptoms is reported, including general malaise, cough, liver function disorder, and, in particular, eosinophilia. Ocular larva migrans may be observed." Since Woodruffs first skin-test studies,2 many investigations have used more sensitive and specific tests to measure the prevalence of the infection in the population Most studies refer to toxocara species, the common roundworm of dogs and cats, because immunologically these species cannot be distinguished. Possibly because of reports about contamination of public parks and children’s sandpits incriminating Toxocara canis/,8 there is a general belief that T canis is the major cause of larva migrans syndrome. In the diagnostic section of our laboratory, clinically suspected from all over the Netherlands are examined for specific antibodies to toxocara.9 In our hands "unexplained eosinophilia", frequently observed in children and adults, could be explained by demonstration of toxocara antibodies in about 35% of the cases only. Therefore, we developed and evaluated a diagnostic test to demonstrate antibodies to other ascarids with Ascaris suum as antigen source."o Both methods use excretory-secretory antigen of cases
SEROEPIDEMIOLOGICAL STUDIES ON TOXOCARAAND ASCARIS IN A HEALTHY POPULATION
551
the second-stage larvae in an ELISA. Crossreactivity between these related nematode larvae is non-existent. This could be proved by using sera from experimentally infected animals and from small population studies in the Netherlands and in Sweden (table).6,1O Virtually no antibodies to both parasites were observed in the same individuals, although both infections occur frequently in the healthy population (7-10%). The difference between parasites and transmission routes is probably the reason for this finding. Further studies will be initiated to unravel the nature of the ascarid larvae causing positive ascaris serology since A lumbricoides has largely disappeared in Dutch residents for many decades. However, eggs of A suum, the common roundworm of pigs, can easily be traced in sewage sludge, which is widely used as cheap fertiliser on agricultural grounds and public parks. Remarkably, in suspected patients, antibodies to both parasites are seen in almost 50% of the seropositive individuals: in 430 Dutch residents, 136 were positive for toxocara and ascaris, 96 were toxocara positive and ascaris negative, and 50 were toxocara negative and ascaris positive. In countries endemic for both toxocara and ascaris, both infections in one person should not be a surprise. Such overlap was not observed in healthy individuals, however. This leads to an interesting hypothesis that repeated infections may be necessary to induce overt toxocarosis or larva migrans syndrome. Previous sensitisation could be induced by toxocara or ascaris and secondary infection with either parasite may lead to clinical manifestations. This observation in suspected cases of larva migrans syndrome has now been observed in over 21years’ laboratory experience, whereas our more intensive population studies in healthy children still indicate that in the Netherlands virtually no double infections occur. The relative importance of nematode larvae other than Toxocara spp as a possible reason for the larva migrans syndrome should be studied on a wider scale, since a considerable percentage of the population may be involved. National Institute of Public Health and Environmental Protection, 3720 BA Bilthoven, Netherlands, and National Bacteriological Laboratory, Stockholm, Sweden
F.
VAN
KNAPEN
J. BUIJS L. M. KORTBEEK I. LJUNGSTRÖM
Taylor MRH, Keane CT, O’Connort P, Girdwood RWA, Smith H. Clinical features of covert toxocariasis. Scand J Infect Dhs 1978; 19: 693. 2 Woodruff A-W. Toxocariasis. BMJ 1970; iii: 633. 3. Jones WE, Schantz PM, Formeman K, Smith KL, Wiotte EJ, Schooley DE, Juranek DD. Human toxocanasis in a rural community. Am J Dis Child 1980; 134: 967. 4 Josephs DS, Bhinder P, Thompson AR. The prevalence of toxocara infection in a child population. Public Health 1981; 95: 273. 5 Tonz M, Speiser F, Tonz O. Toxocariasis bei Schweizer Kindern. Schweiz Med 1
Wochenschr 1983; 113: 1500. 6 Ljungstrom I, van Knapen F An epidemiological and serological study of toxocara infection in Sweden. Scand J Infect Dis 1989; 21: 87-93. 7 Kasieczka J. Zur Kontamination offentlicher Grunflachen und Kinderspielplatze in Wien mit Dauerstadien humanpathogener Endoparasiten vond Hund und Katze. Dissertation Vet Med Univ of Vienna, 1982. 8. Zharova VU Results of an helminthological examination of children’s sandpits and of the surrounding soil. Vopr Med Gel Mintol 1976, 36-38 (in Russian). 9 van Knapen F, Leusden J, Polderman AM, Franchimont JH. Visceral larva migrans: examinations by means of ELISA of human sera for antibodies to excretorysecretory antigens of second-stage larvae of Toxocara canis. Z Parasitenkd 1983; 69: 113
10
P, van Knapen F Immunological studies on Ascaris suum infections in mice. In Geerts S, Kumar V, Brand J, eds. Helminth zoonoses. Dordrecht. Martinus Nijhoff, 1987 149-58.
van Than
Crossreactions between Legionella and
Campylobacter spp SIR,-Dr Andersen and Dr Bangsborg (July 25, p 245) report that serological crossreactions between Legionella pneumophila serogroup 1 and campylobacter are unlikely to occur with a rmcroagglutination technique (MAT). This is in contrast to our report (Jan 18, p 191) and that of Dr Cheesbrough and colleagues ’Feb 15, p 249) of considerable crossreaction with the indirect fluorescent antibody test (IFAT). In the UK, the IFAT is the standard serological test for legionella infecuon, but the rapid microagglutination test (RMAT)1 is also used in laboratories without suitable facilities for
COMPARISON OF LEGION ELLA I FAT AND RMATTITRES FROM 18 PATIENTS WITH CAMPYLOBACTER INFECTION II
I
immunofluorescence. The RMAT is rapid and simple and correlates well with IFAT.1 A titre of 8 or more is regarded as
positive. We have tested by RMAT convalescent serum samples from 18 patients with culture-proven camplylobacter enteritis that crossreacted with legionella by IFAT (table). Both patients with a low IFAT titre (16 and 32) were negative by RMAT, as was 1 with a tife of 64 by IFAT. The other 15 patients were positive by both tests.
These findings clearly demonstrate that crossreaction can also take place in an agglutination assay. This is not surprising since the crossreacting antibodies are mainly IgM class,3which is the principal antibody class detected by microagglutination. The antigen used in the RMAT is formalin-killed whereas the MAT described by Andersen and Bangsborg uses a heat-killed preparation. This difference might account for the discrepancy between our results. However, we are able to absorb the crossreacting antibodies by dilution of serum samples in the supernatant from a heated suspension (100°C for 60 min) of Campylobacter jejuni. This fmding suggests involvement of heatstable antigens. Furthermore, bacterial fluorescence in the IFAT is somatic and not flagellar. We would recommend caution in assuming that crossreaction does not occur with heat-killed antigen because Andersen and Bangsborg’s samples may well have been negative by IFAT as well as MAT. The lack of crossreaction might be explained by the timing of sampling (not stated) or differences in the prevalence of campylobacter serotypes between Denmark and England. We thank Dr J. Webberley, department of microbiology, Worcester Royal Infirmary, for help with the RMAT tests.
Department of Microbiology, Selly Oak Hospital, Birmingham B29 6JD, UK
T. C.
Public Health Laboratory, Northern General Hospital, Sheffield
L. E. MARSHALL G. KUDESIA
J. BOSWELL
TG, Taylor AG. A rapid microagglutination test for the diagnosis of Legionella pneumophila (serogroup 1) infection. J Clin Pathol 1982; 35: 1028-31. 2. Hamson TG, Dournon E, Taylor AG. Evaluation of sensitivity of two serological tests for diagnosing pneumonia caused by Legionella pneumophila serogroup 1. J Clin 1. Harrison
Pathol 1987; 40: 77-82 3 Boswell TCJ, Kudesia G. Serological cross-reaction between Legionella pneumophila and campylobacter in the indirect fluorescent antibody test. Epidermiol Infect (in
press).
SIR,-Dr Boswell and Dr Kudesia kindly gave us 14 serum samples, some from patients noted in their report (Jan 18, p 191),for examination by the indirect immunofluorescence antibody test (IFAT) but with heat-killed legionella antigen1 instead of the formalinised yolk-sac antigen (FYSA) that they used. We also tested the effect of an extract (blocking fluid2) of a randomly chosen strain of Escherichia coli and an extract made in the same way from a randomly chosen strain of Campylobacter jejuni as absorbing agents to see if any crossreactions would be abolished. Not all samples could be examined by all tests because of the small volumes available. 6 acute phase samples from patients with campylobacter infections showed no antibody either with heat-killed or FYSA antigen, and this finding accords with those in Sheffield. The table
regulated to achieve a left ventricular pressure of 80-100% compared with systemic pressure; such obstruction of the pulmonary flow was clinically well tolerated by the child and no further variation of the balloon size was necessary. The position of the balloon was controlled by echocardiography and radiography. Left ventricular wall thickness increased by 50% in the first 24 h of the procedure and then stabilised. Oxygen saturation did not decrease during preparation despite breathing room air. Inotropic support for the first 2 days was reduced and discontinued at the end of the 3rd day. During the subsequent 24 h the child maintained normal left ventricular cavity dimensions and ejection fraction. The increased wall thickness was also maintained without further inotropic support. The mean pressure ratio between left ventricle and systemic pressure during the preparation period was 87-5% (observations were taken every 2 h). An arterial switch was done on the 5th day. The catheters were removed during surgery. No thromboembolic or septic complications occurred and the pulmonary (neoaortic) and mitral valves were normal at inspection. The postoperative course was complicated by bronchopneumonia and myocardial ischaemia with transient ST elevation in inferior and anterolateral leads without evidence of myocardial infarction in the electrocardiograms at discharge. Serial postoperative echocardiograms showed normal ejection fraction and no regional wall-motion abnormalities. There was no further increase in left ventricular wall thickness after surgery. The patient was extubated on the 15th postoperative day and is in excellent physical condition. This technique could be used for preparation of the left ventricle in patients with transposition of the great arteries with intact ventricular septum who did not undergo neonatal repair. In these patients, the adjustability of the grade of obstruction allows preparation of the left ventricle without an aortopulmonary shunt. Patients who have had an atrial repair, such as the Mustard or Senning operation, but whose right ventricle is failing, could also be prepared for arterial switch. A third application could be as an alternative to pulmonary artery banding in critically ill children with complex congenital heart disease. Departments of Cardiology and Cardiac Surgery, Ospedali Riuniti di Bergamo, 24100 Bergamo, Italy; Department of Paediatric Cardiology, Guy’s Hospital, London
they pack gauzes to be autoclaved. The table becomes covered with glove powder. In autotransfusion larger clots are often filtered out through several thicknesses of gauze. A test revealed that this powder easily passed the filter in a blood administration set. I injected rabbits intravenously with an appropriate amount of glove powder (maize starch) suspended in Ringer’s lactate. The result was either no effect or an acute seizure, followed by what appeared as a death caused by a deepening coma within 30 min. There was no foam on the mouth, and cyanosis was difficult to observe. The rabbit’s lungs looked normal to me macroscopically. After consideration and communication with experienced colleagues, I decided to resume autotransfusion in 1991. This is because our hospital trains district doctors who need to be familiar with the technique for use in remote areas. The probable reduction in immunocompetence caused by the transfusion of donor blood3,4 in patients with an HIV infection rate of 30-40% was also a factor. Reclaimed blood is now either filtered through factory-packed new gauzes or a siphon is used to fill the bag.2 No problems have been encountered since. I feel that the glove-powder particles blocked small pulmonary vessels and that the subsequent white blood cell reaction to these foreign bodies must have been responsible for the symptoms of congestive cardiac failure. Obstetrics and Gynaecology Department, United Bulawayo Hospitals, Bulawayo, Zimbabwe 1. Stewart DB. Extra-uterine pregnancy. In: Lawson
JB, Stewart DB, eds. Obstetrics and gynaecology in the tropics and developing countries. London: Edward Arnold, 1967. 375-77. 2. Verkuyl DAA. How I do it: autotransfusion. Med Dig 1990; 16: 115-20. 3. George CD, Morello PJ. Immunologic effect of blood transfusion upon renal transplantation, tumour operations, and bacterial infections. Rev Am J Surg 1986; 152: 329-37 4. Vyas GN. Guest editorial: symposium on transfusion-associated infections and immune response. Transfusion Med Rev 1988; 2: 193-95
Larva
migrans syndrome: toxocara, ascaris, or
PHILIP BONHOEFFER MARIO CARMINATI LUCIO PARENZAN MICHAEL TYNAN
Giglia TM, Sanders SP, et al. Rapid two stage arterial switch for transpostion of the great arteries and intact ventricular septum beyond the neonatal period. Circulation 1989; 80 (suppl I): 203-08. 2. Bonhoeffer Ph, Henry GW, Katayama H, Kresky R, Carminati M, Parenzan L. Preparation of the "pulmonary ventricle" for arterial switch by adjustable intravascular balloon outflow obstruction: an experimental approach in a lamb model. Cardiol Young 1992; 2: 85-88. 1. Jonas RA,
Glove powder introduced in the circulation by autotransfusion and severe cardiac failure SIR,-Since I started working in Africa in 1976,have tried to autotransfusion when possible.1,2 I saw no complications in more than two hundred procedures, apart from some pink colour of urine caused by haemolysis. Twice I saw mild overloading due to use
excessive use of clear fluids in addition to the autotransfusion. But, in 1990, I saw2 patients who died of heart failure after autotransfusion. The autotransfusion programme was suspended. The citrate used for autotransfusion, for economic reasons bottled and sterilised by our blood bank rather than using citrate from disposable collection units, was checked for microorganisms and for toxins on cell cultures, and found free of impurities. I decided to start autotransfusions again. But a girl of 16, admitted with an ectopic pregnancy, had autotransfusion and died of cardiac failure. The autotransfusion programme was again suspended. I speculated that patients with ectopic pregnancies were more likely to be HIV positive and hence more likely to have an infective myocarditis, but this patient was HIV negative. A few months later, I noticed during an operation white dust falling out of abdominal gauzes. During quiet night duties, nursing sisters often repacked surgical gloves on the same table as where
DOUWE A. A. VERKUYL
both?
SiR,—Visceral larva migrans caused by nematode larvae is an increasingly recognised syndrome in man in large parts of the developed world, despite the assumption that most infections go without symptoms. If clinical manifestation occurs, a wide variety of non-specific symptoms is reported, including general malaise, cough, liver function disorder, and, in particular, eosinophilia. Ocular larva migrans may be observed." Since Woodruffs first skin-test studies,2 many investigations have used more sensitive and specific tests to measure the prevalence of the infection in the population Most studies refer to toxocara species, the common roundworm of dogs and cats, because immunologically these species cannot be distinguished. Possibly because of reports about contamination of public parks and children’s sandpits incriminating Toxocara canis/,8 there is a general belief that T canis is the major cause of larva migrans syndrome. In the diagnostic section of our laboratory, clinically suspected from all over the Netherlands are examined for specific antibodies to toxocara.9 In our hands "unexplained eosinophilia", frequently observed in children and adults, could be explained by demonstration of toxocara antibodies in about 35% of the cases only. Therefore, we developed and evaluated a diagnostic test to demonstrate antibodies to other ascarids with Ascaris suum as antigen source."o Both methods use excretory-secretory antigen of cases
SEROEPIDEMIOLOGICAL STUDIES ON TOXOCARAAND ASCARIS IN A HEALTHY POPULATION
551
the second-stage larvae in an ELISA. Crossreactivity between these related nematode larvae is non-existent. This could be proved by using sera from experimentally infected animals and from small population studies in the Netherlands and in Sweden (table).6,1O Virtually no antibodies to both parasites were observed in the same individuals, although both infections occur frequently in the healthy population (7-10%). The difference between parasites and transmission routes is probably the reason for this finding. Further studies will be initiated to unravel the nature of the ascarid larvae causing positive ascaris serology since A lumbricoides has largely disappeared in Dutch residents for many decades. However, eggs of A suum, the common roundworm of pigs, can easily be traced in sewage sludge, which is widely used as cheap fertiliser on agricultural grounds and public parks. Remarkably, in suspected patients, antibodies to both parasites are seen in almost 50% of the seropositive individuals: in 430 Dutch residents, 136 were positive for toxocara and ascaris, 96 were toxocara positive and ascaris negative, and 50 were toxocara negative and ascaris positive. In countries endemic for both toxocara and ascaris, both infections in one person should not be a surprise. Such overlap was not observed in healthy individuals, however. This leads to an interesting hypothesis that repeated infections may be necessary to induce overt toxocarosis or larva migrans syndrome. Previous sensitisation could be induced by toxocara or ascaris and secondary infection with either parasite may lead to clinical manifestations. This observation in suspected cases of larva migrans syndrome has now been observed in over 21years’ laboratory experience, whereas our more intensive population studies in healthy children still indicate that in the Netherlands virtually no double infections occur. The relative importance of nematode larvae other than Toxocara spp as a possible reason for the larva migrans syndrome should be studied on a wider scale, since a considerable percentage of the population may be involved. National Institute of Public Health and Environmental Protection, 3720 BA Bilthoven, Netherlands, and National Bacteriological Laboratory, Stockholm, Sweden
F.
VAN
KNAPEN
J. BUIJS L. M. KORTBEEK I. LJUNGSTRÖM
Taylor MRH, Keane CT, O’Connort P, Girdwood RWA, Smith H. Clinical features of covert toxocariasis. Scand J Infect Dhs 1978; 19: 693. 2 Woodruff A-W. Toxocariasis. BMJ 1970; iii: 633. 3. Jones WE, Schantz PM, Formeman K, Smith KL, Wiotte EJ, Schooley DE, Juranek DD. Human toxocanasis in a rural community. Am J Dis Child 1980; 134: 967. 4 Josephs DS, Bhinder P, Thompson AR. The prevalence of toxocara infection in a child population. Public Health 1981; 95: 273. 5 Tonz M, Speiser F, Tonz O. Toxocariasis bei Schweizer Kindern. Schweiz Med 1
Wochenschr 1983; 113: 1500. 6 Ljungstrom I, van Knapen F An epidemiological and serological study of toxocara infection in Sweden. Scand J Infect Dis 1989; 21: 87-93. 7 Kasieczka J. Zur Kontamination offentlicher Grunflachen und Kinderspielplatze in Wien mit Dauerstadien humanpathogener Endoparasiten vond Hund und Katze. Dissertation Vet Med Univ of Vienna, 1982. 8. Zharova VU Results of an helminthological examination of children’s sandpits and of the surrounding soil. Vopr Med Gel Mintol 1976, 36-38 (in Russian). 9 van Knapen F, Leusden J, Polderman AM, Franchimont JH. Visceral larva migrans: examinations by means of ELISA of human sera for antibodies to excretorysecretory antigens of second-stage larvae of Toxocara canis. Z Parasitenkd 1983; 69: 113
10
P, van Knapen F Immunological studies on Ascaris suum infections in mice. In Geerts S, Kumar V, Brand J, eds. Helminth zoonoses. Dordrecht. Martinus Nijhoff, 1987 149-58.
van Than
Crossreactions between Legionella and
Campylobacter spp SIR,-Dr Andersen and Dr Bangsborg (July 25, p 245) report that serological crossreactions between Legionella pneumophila serogroup 1 and campylobacter are unlikely to occur with a rmcroagglutination technique (MAT). This is in contrast to our report (Jan 18, p 191) and that of Dr Cheesbrough and colleagues ’Feb 15, p 249) of considerable crossreaction with the indirect fluorescent antibody test (IFAT). In the UK, the IFAT is the standard serological test for legionella infecuon, but the rapid microagglutination test (RMAT)1 is also used in laboratories without suitable facilities for
COMPARISON OF LEGION ELLA I FAT AND RMATTITRES FROM 18 PATIENTS WITH CAMPYLOBACTER INFECTION II
I
immunofluorescence. The RMAT is rapid and simple and correlates well with IFAT.1 A titre of 8 or more is regarded as
positive. We have tested by RMAT convalescent serum samples from 18 patients with culture-proven camplylobacter enteritis that crossreacted with legionella by IFAT (table). Both patients with a low IFAT titre (16 and 32) were negative by RMAT, as was 1 with a tife of 64 by IFAT. The other 15 patients were positive by both tests.
These findings clearly demonstrate that crossreaction can also take place in an agglutination assay. This is not surprising since the crossreacting antibodies are mainly IgM class,3which is the principal antibody class detected by microagglutination. The antigen used in the RMAT is formalin-killed whereas the MAT described by Andersen and Bangsborg uses a heat-killed preparation. This difference might account for the discrepancy between our results. However, we are able to absorb the crossreacting antibodies by dilution of serum samples in the supernatant from a heated suspension (100°C for 60 min) of Campylobacter jejuni. This fmding suggests involvement of heatstable antigens. Furthermore, bacterial fluorescence in the IFAT is somatic and not flagellar. We would recommend caution in assuming that crossreaction does not occur with heat-killed antigen because Andersen and Bangsborg’s samples may well have been negative by IFAT as well as MAT. The lack of crossreaction might be explained by the timing of sampling (not stated) or differences in the prevalence of campylobacter serotypes between Denmark and England. We thank Dr J. Webberley, department of microbiology, Worcester Royal Infirmary, for help with the RMAT tests.
Department of Microbiology, Selly Oak Hospital, Birmingham B29 6JD, UK
T. C.
Public Health Laboratory, Northern General Hospital, Sheffield
L. E. MARSHALL G. KUDESIA
J. BOSWELL
TG, Taylor AG. A rapid microagglutination test for the diagnosis of Legionella pneumophila (serogroup 1) infection. J Clin Pathol 1982; 35: 1028-31. 2. Hamson TG, Dournon E, Taylor AG. Evaluation of sensitivity of two serological tests for diagnosing pneumonia caused by Legionella pneumophila serogroup 1. J Clin 1. Harrison
Pathol 1987; 40: 77-82 3 Boswell TCJ, Kudesia G. Serological cross-reaction between Legionella pneumophila and campylobacter in the indirect fluorescent antibody test. Epidermiol Infect (in
press).
SIR,-Dr Boswell and Dr Kudesia kindly gave us 14 serum samples, some from patients noted in their report (Jan 18, p 191),for examination by the indirect immunofluorescence antibody test (IFAT) but with heat-killed legionella antigen1 instead of the formalinised yolk-sac antigen (FYSA) that they used. We also tested the effect of an extract (blocking fluid2) of a randomly chosen strain of Escherichia coli and an extract made in the same way from a randomly chosen strain of Campylobacter jejuni as absorbing agents to see if any crossreactions would be abolished. Not all samples could be examined by all tests because of the small volumes available. 6 acute phase samples from patients with campylobacter infections showed no antibody either with heat-killed or FYSA antigen, and this finding accords with those in Sheffield. The table
