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Diarrhoea associated with Escherichia coli producing porcine oedema disease verotoxin
762
noisier than the 05 T unit, which is only 160 cm long and has a minimum diameter of 70 cm for 40 cm (’Gyroscan T5’, Philips). The frequency of claustrophobia might be expected to be lower in the 0-5 T machine with its wider and shorter tunnel. However, there was hardly any difference (0-51% [5/975] narrow tunnel, 0.46% [6/1314] wide tunnel). When we asked staff about how they assigned patients to one machine or the other a possible explanation emerged. The staff referred anxious patients thought likely to have a claustrophobic reaction to the 0-5 T machine, thus diverting high-risk patients from the narrower tunnel. This suggests that the wide-tunnel machine really did reduce claustrophobia. This suggestion must be regarded with caution since the study
retrospective. A prospective trial is in progress. In view of the steadily rising number of MRI scans, the avoidance of claustrophobic reactions could be an important consideration when selecting MRI machines for routine work. was
Psychiatric Clinic, Department of Radiology, and MR Institute,
University of Vienna, A-1090 Vienna, Austria
KARL DANTENDORFER DANIELA WIMBERGER HEINZ KATSCHNIG HERWIG IMHOFF
1. Avrahami E. Panic attacks during MR-imaging. Am J Neuroradiol 1990; 11: 833-35. 2. Kilborn LC, Labbe EE. MRI scanning procedures, development of phobic response. J Behav Med 1990; 13: 339-401. 3. Klein DS. Prevention of claustrophobia induced by MRI. Am J Roentgenol 1991; 156: 633. 4. Oberstein A, Meves M, et al. Beeintrachtigende Faktoren in der MRRoutineanwendung. Digit Bilddiagn 1990; 10: 10-16.
frequent source of human infection. VTe-producing E coli strains could be present in pork products and be transmitted to man but the described here is the first well-documented human isolation of a strain. Brown et al’° found some strains producing VT that they characterised as VTe because the strains were not cytotoxic for hela cells and hybridised with VT2 oligonucleotide probes at low temperature only. It now seems more likely, however, that these strains produced VT2vh-a or VT2vh-b. In our patient a history of possible infection sources is not available. The rarity of isolation of VTe-producing E coli from human faeces could be related to lack of pathogenicity in man. The different cell toxicity ofVT1/VT2 and VTe probably correspond to differences in receptor specificity: VT 1 and VT2 bind specifically to globotriosylceramide (Gb3) whereas VTe binds to globotetraosylceramide (Gb4).5 These glycolipids could be selectively present on the enterocytes of different mammalian species. Another possibility is that the strains associated with porcine disease (most frequently haemolytic strains of serotypes 0138, 0139, 0141, and, in a Belgian study0149) possess an adherence factor that does not attach to human enterocytes. The strain from our patient, belonging to a serotype not usually associated with disease in piglets, could harbour a different adherence factor, leading to diarrhoea in man. case
such
Departments of Microbiology and Critical Care Medicine, B1090-Brussels, Belgium
DENIS PIERARD LUC HUYGHENS SABINE LAUWERS
Laboratory for Enteric Pathogens, Laboratory Centre for Disease Control, Ottawa, Ontario, Canada
HERMY LIOR
Academisch Ziekenhuis, Free University of Brussels,
National
Diarrhoea associated with Escherichia coli
producing porcine oedema disease verotoxin SIR,-Escherichia coli verotoxins (shiga-like-toxins) are a family of related cytotoxins. In man the isolation of strains producing VT1 and VT2 has been closely associated with sporadic diarrhoea, haemolytic uraemic syndrome, and thrombotic thrombocytopenic purpura.1 In animals, verotoxin-producing E coli (VTEC) has been associated with porcine oedema disease, a frequently fatal illness in weanling pigs.2 Dobrescu3 reported that the "oedema disease principle" produced by these strains is antigenically similar to VT2. Unlike VT1 and VT2, this verotoxin (VTe) is not active on hela cells." The genes for VT1 and VT2 share only 55-60% nucleotide sequence homology whereas the A toxin subunit genes of VT2 and VTe are highly homologous (94%), the B toxin subunit genes being less so (78%-80%).5 Two other variant toxins, VT2vh a and b6,7 are also cytotoxic for Vero cells but show a reduced toxicity for hela cells. The nucleotide sequences of their A and B subunits are almost identical (99% homology) and exhibit 98-6% and 95-5% homology, respectively, with those of the VT2 gene, compared with 94-5% and 82-8% homology with those of the VTe gene. Restriction fragment length polymorphism analysis indicates that these VT2 variant genes may be fairly common among VTECs.6 While screening for VTEC in faeces, making use of the polymerase chain reaction (PCR) with a single primer pair that permits amplification of VT1, VT2, and VTe genes, we isolated a strain producing VTe from a 72-year-old man admitted to intensive care. He had been resuscitated outside hospital after ventricular fibrillation due to acute myocardial infarction. He was in postanoxic coma and status epilepticus, and aspiration pneumonia developed. On day 6 liquid diarrhoea without blood appeared, and this persisted until the patient died in status epilepticus on day 12. A faecal sample taken on day 6 was positive for VTEC and negative for salmonella, shigella, yersinia, campylobacter, and parasites. PCR testing of ten individual coliform colonies yielded nine VTECs; on PCR with specific primers for VT1 and VT29 all nine were negative. Cytotoxicity was positive on Vero cells (but negative on hela cells) and was neutralisable by VTe antiserum. PCR using VTe-specific primers4 was positive, showing that this strain contained the VTe gene. The serotype was 0101:H9, which is not usually associated with oedema disease in pigs. Isolation of VTEC (producing VT1and/or VT2) from cattle and beef meat has often been reported and is suspected to be the most
1. Karmali MA. Infection by verocytotoxin-producing Escherichia coli. Clin Microbiol Rev 1989; 2: 15-38. 2. Pohl P, Lintermans P, Mainil J, Deprez P. Production de vérocytotoxine par les Escherichia coli du porc. Ann Méd Vét 1989; 133: 31-38. 3. Dobrescu L. New biological effect of edema disease principle (Escherichia colineurotoxin) and its use as an in vitro assay for this toxin. Am J Vet Res 1983; 44: 31-34. 4. Johnson WM, Pollard DR, Lior H, Tyler SD, Rozee KR. Differentiation of genes coding for Escherichia coli verotoxin 2 and the verotoxin associated with porcine edema disease (VTe) by the polymerase chain reaction. J Clin Microbiol 1990; 28: 2351-53. 5. Gannon VPJ, Teerling C, Masn SA, Gyles CL. Molecular cloning and nucleotide sequence of another vanant of the Escherichia coli shiga-like-toxin II family. J Gen 6. Ito
Microbiol 1990; 136: 1125-35. H, Teral A, Kurazono H, Takeda Y, Nishibuchi M. Cloning and nucleotide
sequencing of vero toxin 2 vanant genes from Escherichia coli O91:H21 isolated from a patient with hemolytic uremic syndrome. Microb Pathog 1990; 8: 47-60. 7. Tyler SD, Johnson WM, Lior H, Rozee KR. Identification of verotoxin type 2 variant B subunit genes in Escherichia coli by the polymerase chain reaction and restriction fragment length polymorphism analysis. J Clin Microbiol 1991; 29: 1339-43. 8. Karch H, Meyer T. Single primer pair for amplifying segments of distinct shiga-like-toxin genes by polymerase chain reaction. J Clin Microbiol 1989; 27: 2751-57. 9. Pollard DR, Johnson WM, Lior H, Tyler SD, Rozee KR. Rapid and specific detection of verotoxin genes in Escherichia colt by the polymerase chain reaction. J Clin Microbiol 1990; 28: 540-45. 10. Brown JE, Sethabutr O, Jackson MP, Lolekha S, Echeverria P. Hybridization of Escherichia coli producing shiga-like toxin I, shiga-like toxin II, and a vanant of shiga-like toxin II with synthetic oligonucleotide probes Infect Immun 1989; 57: 2811-14.
Enterococcus faecium with high-level resistance to gentamicin SiR,—Dr Bendall and colleagues (Aug 17, p 445) state that the of high-level gentamicin resistance (HLGR) among enterococci is underestimated. We report our experience in Brooklyn, New York.
prevalence
We undertook a routine surveillance of HLGR among enterococci isolated from blood cultures obtained from febrile patients over a six-month period (January to July, 1990). Unexpectedly, the frequency of HLGR among the 50 or so isolates tested was 54%The rate expected on the basis of previous reports was about 15%.2 We retrospectively reviewed the patients’ records and found that the clinical outcome did not differ significantly from that of matched controls (patients from the same time period with enterococci isolated from blood cultures that did not show HLGR).
noisier than the 05 T unit, which is only 160 cm long and has a minimum diameter of 70 cm for 40 cm (’Gyroscan T5’, Philips). The frequency of claustrophobia might be expected to be lower in the 0-5 T machine with its wider and shorter tunnel. However, there was hardly any difference (0-51% [5/975] narrow tunnel, 0.46% [6/1314] wide tunnel). When we asked staff about how they assigned patients to one machine or the other a possible explanation emerged. The staff referred anxious patients thought likely to have a claustrophobic reaction to the 0-5 T machine, thus diverting high-risk patients from the narrower tunnel. This suggests that the wide-tunnel machine really did reduce claustrophobia. This suggestion must be regarded with caution since the study
retrospective. A prospective trial is in progress. In view of the steadily rising number of MRI scans, the avoidance of claustrophobic reactions could be an important consideration when selecting MRI machines for routine work. was
Psychiatric Clinic, Department of Radiology, and MR Institute,
University of Vienna, A-1090 Vienna, Austria
KARL DANTENDORFER DANIELA WIMBERGER HEINZ KATSCHNIG HERWIG IMHOFF
1. Avrahami E. Panic attacks during MR-imaging. Am J Neuroradiol 1990; 11: 833-35. 2. Kilborn LC, Labbe EE. MRI scanning procedures, development of phobic response. J Behav Med 1990; 13: 339-401. 3. Klein DS. Prevention of claustrophobia induced by MRI. Am J Roentgenol 1991; 156: 633. 4. Oberstein A, Meves M, et al. Beeintrachtigende Faktoren in der MRRoutineanwendung. Digit Bilddiagn 1990; 10: 10-16.
frequent source of human infection. VTe-producing E coli strains could be present in pork products and be transmitted to man but the described here is the first well-documented human isolation of a strain. Brown et al’° found some strains producing VT that they characterised as VTe because the strains were not cytotoxic for hela cells and hybridised with VT2 oligonucleotide probes at low temperature only. It now seems more likely, however, that these strains produced VT2vh-a or VT2vh-b. In our patient a history of possible infection sources is not available. The rarity of isolation of VTe-producing E coli from human faeces could be related to lack of pathogenicity in man. The different cell toxicity ofVT1/VT2 and VTe probably correspond to differences in receptor specificity: VT 1 and VT2 bind specifically to globotriosylceramide (Gb3) whereas VTe binds to globotetraosylceramide (Gb4).5 These glycolipids could be selectively present on the enterocytes of different mammalian species. Another possibility is that the strains associated with porcine disease (most frequently haemolytic strains of serotypes 0138, 0139, 0141, and, in a Belgian study0149) possess an adherence factor that does not attach to human enterocytes. The strain from our patient, belonging to a serotype not usually associated with disease in piglets, could harbour a different adherence factor, leading to diarrhoea in man. case
such
Departments of Microbiology and Critical Care Medicine, B1090-Brussels, Belgium
DENIS PIERARD LUC HUYGHENS SABINE LAUWERS
Laboratory for Enteric Pathogens, Laboratory Centre for Disease Control, Ottawa, Ontario, Canada
HERMY LIOR
Academisch Ziekenhuis, Free University of Brussels,
National
Diarrhoea associated with Escherichia coli
producing porcine oedema disease verotoxin SIR,-Escherichia coli verotoxins (shiga-like-toxins) are a family of related cytotoxins. In man the isolation of strains producing VT1 and VT2 has been closely associated with sporadic diarrhoea, haemolytic uraemic syndrome, and thrombotic thrombocytopenic purpura.1 In animals, verotoxin-producing E coli (VTEC) has been associated with porcine oedema disease, a frequently fatal illness in weanling pigs.2 Dobrescu3 reported that the "oedema disease principle" produced by these strains is antigenically similar to VT2. Unlike VT1 and VT2, this verotoxin (VTe) is not active on hela cells." The genes for VT1 and VT2 share only 55-60% nucleotide sequence homology whereas the A toxin subunit genes of VT2 and VTe are highly homologous (94%), the B toxin subunit genes being less so (78%-80%).5 Two other variant toxins, VT2vh a and b6,7 are also cytotoxic for Vero cells but show a reduced toxicity for hela cells. The nucleotide sequences of their A and B subunits are almost identical (99% homology) and exhibit 98-6% and 95-5% homology, respectively, with those of the VT2 gene, compared with 94-5% and 82-8% homology with those of the VTe gene. Restriction fragment length polymorphism analysis indicates that these VT2 variant genes may be fairly common among VTECs.6 While screening for VTEC in faeces, making use of the polymerase chain reaction (PCR) with a single primer pair that permits amplification of VT1, VT2, and VTe genes, we isolated a strain producing VTe from a 72-year-old man admitted to intensive care. He had been resuscitated outside hospital after ventricular fibrillation due to acute myocardial infarction. He was in postanoxic coma and status epilepticus, and aspiration pneumonia developed. On day 6 liquid diarrhoea without blood appeared, and this persisted until the patient died in status epilepticus on day 12. A faecal sample taken on day 6 was positive for VTEC and negative for salmonella, shigella, yersinia, campylobacter, and parasites. PCR testing of ten individual coliform colonies yielded nine VTECs; on PCR with specific primers for VT1 and VT29 all nine were negative. Cytotoxicity was positive on Vero cells (but negative on hela cells) and was neutralisable by VTe antiserum. PCR using VTe-specific primers4 was positive, showing that this strain contained the VTe gene. The serotype was 0101:H9, which is not usually associated with oedema disease in pigs. Isolation of VTEC (producing VT1and/or VT2) from cattle and beef meat has often been reported and is suspected to be the most
1. Karmali MA. Infection by verocytotoxin-producing Escherichia coli. Clin Microbiol Rev 1989; 2: 15-38. 2. Pohl P, Lintermans P, Mainil J, Deprez P. Production de vérocytotoxine par les Escherichia coli du porc. Ann Méd Vét 1989; 133: 31-38. 3. Dobrescu L. New biological effect of edema disease principle (Escherichia colineurotoxin) and its use as an in vitro assay for this toxin. Am J Vet Res 1983; 44: 31-34. 4. Johnson WM, Pollard DR, Lior H, Tyler SD, Rozee KR. Differentiation of genes coding for Escherichia coli verotoxin 2 and the verotoxin associated with porcine edema disease (VTe) by the polymerase chain reaction. J Clin Microbiol 1990; 28: 2351-53. 5. Gannon VPJ, Teerling C, Masn SA, Gyles CL. Molecular cloning and nucleotide sequence of another vanant of the Escherichia coli shiga-like-toxin II family. J Gen 6. Ito
Microbiol 1990; 136: 1125-35. H, Teral A, Kurazono H, Takeda Y, Nishibuchi M. Cloning and nucleotide
sequencing of vero toxin 2 vanant genes from Escherichia coli O91:H21 isolated from a patient with hemolytic uremic syndrome. Microb Pathog 1990; 8: 47-60. 7. Tyler SD, Johnson WM, Lior H, Rozee KR. Identification of verotoxin type 2 variant B subunit genes in Escherichia coli by the polymerase chain reaction and restriction fragment length polymorphism analysis. J Clin Microbiol 1991; 29: 1339-43. 8. Karch H, Meyer T. Single primer pair for amplifying segments of distinct shiga-like-toxin genes by polymerase chain reaction. J Clin Microbiol 1989; 27: 2751-57. 9. Pollard DR, Johnson WM, Lior H, Tyler SD, Rozee KR. Rapid and specific detection of verotoxin genes in Escherichia colt by the polymerase chain reaction. J Clin Microbiol 1990; 28: 540-45. 10. Brown JE, Sethabutr O, Jackson MP, Lolekha S, Echeverria P. Hybridization of Escherichia coli producing shiga-like toxin I, shiga-like toxin II, and a vanant of shiga-like toxin II with synthetic oligonucleotide probes Infect Immun 1989; 57: 2811-14.
Enterococcus faecium with high-level resistance to gentamicin SiR,—Dr Bendall and colleagues (Aug 17, p 445) state that the of high-level gentamicin resistance (HLGR) among enterococci is underestimated. We report our experience in Brooklyn, New York.
prevalence
We undertook a routine surveillance of HLGR among enterococci isolated from blood cultures obtained from febrile patients over a six-month period (January to July, 1990). Unexpectedly, the frequency of HLGR among the 50 or so isolates tested was 54%The rate expected on the basis of previous reports was about 15%.2 We retrospectively reviewed the patients’ records and found that the clinical outcome did not differ significantly from that of matched controls (patients from the same time period with enterococci isolated from blood cultures that did not show HLGR).