Species and biotypes of Streptococcus bovis causing infective endocarditis

INTRODUCTION

Streptococcus bovis/equinus complex (SBEC) is a major cause of infective endocarditis (IE), although its incidence varies greatly depending on the geographical area. The characteristics of IE caused by Streptococcus gallolyticus susp. gallolyticus are well known; there are hardly any descriptions of IE caused by other species or biotypes.

METHODS

Retrospective cohort study, from 1990 to 2019, of all SBEC IE in adults in three Spanish hospitals, Lugo (LH), Barcelona (BH) and Ferrol (FH) where the population is mainly rural, urban and mixed, respectively. The incidence of IE was analyzed in 3 areas. Clinical characteristics of IE (277 cases, 258 biotyped) were compared according to SBEC species and biotypes.

RESULTS

There are significant differences between the incidence of SBEC IE in HL (27.9/10⁶) vs. HF and HB (8.8 and 7,1, respectively, p<0.001). We found significant differences (SbI vs. SbII) in mean age (68.5 vs. 73 years; p<0.01), duration of symptoms before diagnosis (46.9±46.5 vs. 30.4±40.9 days; p<0.01), presence of comorbidities: 39.1% (78) vs. 54.2% (32; p<0.04), predisposing heart illness:62.3% (124) vs. 81.3% (48; p<0.006), particularly, prosthetic or intravascular devices IE: 24.6% (49) vs. 52.4% (31; p<0.001), bi-valve involvement:23.6% (47) vs. 11.8% (7; p<0.05) and heart failure: 24.6% (49) vs. 38.9% (23; p<0.03). There were no significant differences in embolic events, need for surgery or mortality. The association with CRC was high in both groups: 77.7% vs. 66.6%.

CONCLUSIONS

IE due to SBEC has geographical variations in incidence and different clinical characteristics among biotypes. The association with CRC was high.

Is Streptococcus bovis a urinary pathogen?

The Streptococcus bovis group (SBG) comprises several microorganisms associated with human infections. They have been associated with bacteremia, endocarditis, biliary tract infection, meningitis, and colorectal cancer, but their role as urinary pathogens is not well known. The objective of this investigation was to discover the incidence and clinical significance of the bacteriuria associated with this complex. A retrospective analysis of all adult patients with bacteriuria caused by SBG during the period 1995-2012 was carried out. During the study period, SBG was isolated in 153 adult patients, who had a mean age of 67 years, most of them being women (80%). Most of our patients (65%) had some underlying disease, with urologic disease being the most common (37%), followed by diabetes mellitus (27%) and neurologic disease (25%). Among the 88 patients in whom we were able to correctly assess symptoms, 45% had asymptomatic bacteriuria, 35% had lower urinary tract infection, and 20% had upper urinary tract infection. In 14 cases (9%), SBG was also isolated in blood cultures. Most of the isolates of SBG (72%) were S. gallolyticus subsp. pasteurianus. All isolates were susceptible to penicillin, 98% to nitrofurantoin, and 77% to fosfomycin. Although SBG bacteriuria is uncommon, it should not always be taken as a contaminant, mainly when S. pasteurianus is isolated, because it may cause urinary tract infections and, occasionally, sepsis, whereas when S. gallolyticus is isolated from urine, it may be a marker of underlying endocarditis and colorectal cancer.

Streptococcus bovis group and biliary tract infections: an analysis of 51 cases

Streptococcus bovis is a well-known cause of endocarditis, but its role in other infections has not been well described. We analysed prospectively all patients with biliary tract infections caused by S. bovis group during the period 1988-2011. We selected those cases associated with cholangitis and cholecystitis, defined according to Tokyo guidelines. Identification of the strains was performed using the API 20 Strep and the GP card of the Vitek 2 system, and was confirmed by molecular methods. Our series included 51 cases (30 cholangitis and 21 cholecystitis). The associated microorganisms were: Streptococcus infantarius (biotype II/1) 29 cases (57%), Streptococcus gallolyticus subsp. pasteurianus (biotype II/2) 20 cases (39%) and Streptococcus gallolyticus subsp. gallolyticus (biotype I) two cases (4%). The only difference found between S. infantarius and S. gallolyticus subsp. pasteurianus was a greater association of the first with malignant strictures of the bile ducts: 48% (14/29) versus 5% (1/20), p <0.001. Thirty-seven of the cases also had bacteraemia, causing 20% (37/185) of all S. bovis bacteraemia, with differences between S. gallolyticus subsp. gallolyticus (2/112; 2%) and the other two microorganisms: S. infantarius and S. gallolyticus subsp. pasteurianus (35/73; 48%; p <0.001). The vast majority of biliary tract infections due to S. bovis group are caused by S. infantarius and S. gallolyticus subsp. pasteurianus (S. bovis biotype II), and nearly half of the bacteraemia due to these two species has a biliary source (43% of the S. infantarius and 56% of S. gallolyticus subsp. pasteurianus).

Comparative electron temperature measurements of Thomson scattering and electron cyclotron emission diagnostics in TCABR plasmas

We present the first simultaneous measurements of the Thomson scattering and electron cyclotron emission radiometer diagnostics performed at TCABR tokamak with Alfvén wave heating. The Thomson scattering diagnostic is an upgraded version of the one previously installed at the ISTTOK tokamak, while the electron cyclotron emission radiometer employs a heterodyne sweeping radiometer. For purely Ohmic discharges, the electron temperature measurements from both diagnostics are in good agreement. Additional Alfvén wave heating does not affect the capability of the Thomson scattering diagnostic to measure the instantaneous electron temperature, whereas measurements from the electron cyclotron emission radiometer become underestimates of the actual temperature values.

Comorbidity in pathological gambling: clinical variables, personality and treatment response

INTRODUCTION

Pathological gambling shows high comorbidity rates, especially with substance use disorders, although affective, anxiety and other impulse control disorders, as well as personality disorders, are also frequently associated.

OBJECTIVES

To explore comorbidity in pathological gambling with other mental disorders in a consecutive sample of patients attending a unit specialized in pathological gambling, and specifically the relationship between substance-related disorders, on the one hand, and personality and clinical variables in pathological gamblers, on the other.

METHOD

A total of 498 patients with a DSM-IV-TR diagnosis of Pathological Gambling (11.8% women) were assessed with a semi-structured clinical interview and several clinical and personality scales.

RESULTS

Higher comorbidity with affective disorders was found in women (30.5%), while higher comorbidity with substance-related disorders was found in men (11.2%). A positive association was also detected between a history of psychiatric disorders and current comorbidity with substance-use disorders, as well as between alcohol abuse and age. Finally, some personality traits such as low reward dependence (OR=0.964) and high impulsivity (OR=1.02) predicted other substance abuse (not alcohol). High selftranscendence scores predicted both alcohol and other substance abuse (OR=1.06).

CONCLUSIONS

Our results suggest a high prevalence of comorbid disorders in pathologic gambling, mainly with affective and substance-related disorders. The results of the present study, conducted in a broad sample of consecutively admitted pathologic gamblers, may contribute to understanding of this complex disorder and treatment improvement.

Characteristics of Streptococcus bovis endocarditis and its differences with Streptococcus viridans endocarditis

The purpose of this study was to evaluate the characteristics of infective endocarditis (IE) caused by S. bovis and compare them to those caused by streptococci of the viridans group (SVG). A prospective study was undertaken considering 55 consecutive cases of IE due to S. bovis and 41 to SVG over 18 years. The study was divided into two periods (1988-1996 and 1997-2005). S. bovis caused 24% of the IE in our centre and constituted the main aetiology for this disease, showing an increase of 358% during the second period studied. Biotype I was responsible for 94.5% of cases and there was a high degree of association with colon tumours (53%). Over the period of the study, 107 patients admitted to our hospital had bacteraemia caused by S. bovis and 310 patients had bacteraemia caused by SVG. In the first group, 55 (51%) were endocarditis cases, but only 41 (13%) of the patients with SVG bacteraemia had endocarditis (p < 0.0001). The distinguishing features of endocarditis caused by S. bovis in comparison with those caused by SGV were: a greater increase in cases during the 2nd period studied (from 12 to 43 vs. from 19 to 22, p < 0.01), a higher percentage of males (93% vs. 71%, p < 0.004), patients significantly older (median age 66 vs. 58.5, p < 0.004), less predisposing cardiopathy (42% vs. 76%, p < 0.0009), more bivalvular involvement (42% vs. 22%, p < 0.04), more spondylitis (9% vs. 0%, p < 0.04), a higher association with colonic tumours (53% vs. 5%, p < 0.0001), and a higher percentage of antibiotic resistance: erythromycin 66% vs. 19%, p < 0.0001; clindamycin 67% vs. 11%, p < 0.0001; cotrimoxazole 77% vs. 30.5%, p < 0.0001, respectively. IE due to S. bovis is an emergent disease in our environment, presenting different characteristics to those produced by SVG.

Clinical characteristics and significance of Streptococcus salivarius bacteremia and Streptococcus bovis bacteremia: a prospective 16-year study

The aim of this study was to determine the clinical significance of Streptococcus salivarius isolates recovered from blood cultures and compare them with isolates of Streptococcus bovis biotypes I and II. Seventeen of the 52 (32%) S. salivarius isolates recovered were considered clinically significant, compared with 62 of the 64 (97%) S. bovis isolates (p<0.0001). Bacteremia caused by S. salivarius occurred mostly in patients who showed relevant disruption of the mucous membranes and/or serious underlying diseases. Patients with S. salivarius bacteremia were younger than those with S. bovis bacteremia (57 vs. 67 years; p<0.01). Patients with S. salivarius bacteremia and patients with S. bovis II bacteremia had similar rates of endocarditis, colon tumors, and non-colon cancer. On the other hand, when compared with S. bovis I bacteremia, S. salivarius bacteremia was associated with lower rates of endocarditis (18% vs. 74%, respectively) (p<0.01) and colon tumors (0% vs. 57%, respectively) (p<0.005) and higher rates of non-colon cancer (53% vs. 9.5%, respectively) (p<0.01). Bacteremia caused by S. bovis II had a hepatobiliary origin in 50% of the patients, while, in contrast, that due to S. salivarius or S. bovis I was less frequently associated with a hepatobiliary origin (12% and 5%, respectively) (p<0.00001). The rate of penicillin resistance was 31% among S. salivarius isolates and 0% among S. bovis isolates (p<0.0001). In conclusion, the clinical characteristics of S. salivarius bacteremia and S. bovis II bacteremia are similar, and the isolation of S. salivarius in blood should not be systematically regarded as contamination.

Serotypes, virulence genes, and intimin types of Shiga toxin (verotoxin)-producing Escherichia coli isolates from cattle in Spain and identification of a new intimin variant gene (eae-xi)

A total of 514 Shiga toxin-producing Escherichia coli (STEC) isolates from diarrheic and healthy cattle in Spain were characterized in this study. PCR showed that 101 (20%) isolates carried stx(1) genes, 278 (54%) possessed stx(2) genes, and 135 (26%) possessed both stx(1) and stx(2). Enterohemolysin (ehxA) and intimin (eae) virulence genes were detected in 326 (63%) and in 151 (29%) of the isolates, respectively. STEC isolates belonged to 66 O serogroups and 113 O:H serotypes (including 23 new serotypes). However, 67% were of one of these 15 serogroups (O2, O4, O8, O20, O22, O26, O77, O91, O105, O113, O116, O157, O171, O174, and OX177) and 52% of the isolates belonged to only 10 serotypes (O4:H4, O20:H19, O22:H8, O26:H11, O77:H41, O105:H18, O113:H21, O157:H7, O171:H2, and ONT:H19). Although the 514 STEC isolates belonged to 164 different seropathotypes (associations between serotypes and virulence genes), only 12 accounted for 43% of isolates. Seropathotype O157:H7 stx(2) eae-gamma1 ehxA (46 isolates) was the most common, followed by O157:H7 stx(1) stx(2) eae-gamma1 ehxA (34 isolates), O113:H21 stx(2) (25 isolates), O22:H8 stx(1) stx(2) ehxA (15 isolates), O26:H11 stx(1) eae-beta1 ehxA (14 isolates), and O77:H41 stx(2) ehxA (14 isolates). Forty-one (22 of serotype O26:H11) isolates had intimin beta1, 82 O157:H7 isolates possessed intimin gamma1, three O111:H- isolates had intimin type gamma2, one O49:H- strain showed intimin type delta, 13 (six of serotype O103:H2) isolates had intimin type epsilon and eight (four of serotype O156:H-) isolates had intimin zeta. We have identified a new variant of the eae intimin gene designated xi (xi) in two isolates of serotype O80:H-. The majority (85%) of bovine STEC isolates belonged to serotypes previously found for human STEC organisms and 54% to serotypes associated with STEC organisms isolated from patients with hemolytic uremic syndrome. Thus, this study confirms that cattle are a major reservoir of STEC strains pathogenic for humans.

Serotypes, virulence genes, and intimin types of Shiga toxin (verotoxin)-producing Escherichia coli isolates from human patients: prevalence in Lugo, Spain, from 1992 through 1999

We have analyzed the prevalence of Shiga toxin-producing Escherichia coli (STEC) in stool specimens of patients with diarrhea or other gastrointestinal alterations from the Xeral-Calde Hospital of Lugo City (Spain). STEC strains were detected in 126 (2.5%) of 5,054 cases investigated, with a progressive increase in the incidence from 0% in 1992 to 4.4% in 1999. STEC O157:H7 was isolated in 24 cases (0.5%), whereas non-O157 STEC strains were isolated from 87 patients (1.7%). STEC strains were (after Salmonella and Campylobacter strains) the third most frequently recovered enteropathogenic bacteria. A total of 126 human STEC isolates were characterized in this study. PCR showed that 43 (34%) isolates carried stx(1) genes, 45 (36%) possessed stx(2) genes and 38 (30%) carried both stx(1) and stx(2). A total of 88 (70%) isolates carried an ehxA enterohemolysin gene, and 70 (56%) isolates possessed an eae intimin gene (27 isolates with type gamma1, 20 with type beta1, 8 with type zeta, 5 with type gamma2, and 3 with type epsilon). STEC isolates belonged to 41 O serogroups and 66 O:H serotypes, including 21 serotypes associated with hemolytic uremic syndrome and 30 new serotypes not previously reported among human STEC strains in other studies. Although the 126 STEC isolates belonged to 81 different seropathotypes (associations between serotypes and virulence genes), only four accounted for 31% of isolates. Seropathotype O157:H7 stx(1) stx(2) eae-gamma1 ehxA was the most common (13 isolates) followed by O157:H7 stx(2) eae-gamma1 ehxA (11 isolates), O26:H11 stx(1) eae-beta1 ehxA (11 isolates), and O111:H- stx(1) stx(2) eae-gamma2 ehxA (4 isolates). Our results suggest that STEC strains are a significant cause of human infections in Spain and confirm that in continental Europe, infections caused by STEC non-O157 strains are more common than those caused by O157:H7 isolates. The high prevalence of STEC strains (both O157:H7 and non-O157 strains) in human patients, and their association with serious complications, strongly supports the utilization of protocols for detection of all serotypes of STEC in Spanish clinical microbiology laboratories.

Serotypes, virulence genes, and intimin types of Shiga toxin (verotoxin)-producing Escherichia coli isolates from healthy sheep in Spain

Fecal swabs obtained from 1,300 healthy lambs in 93 flocks in Spain in 1997 were examined for Shiga toxin-producing Escherichia coli (STEC). STEC O157:H7 strains were isolated from 5 (0.4%) animals in 4 flocks, and non-O157 STEC strains were isolated from 462 (36%) lambs in 63 flocks. A total of 384 ovine STEC strains were characterized in this study. PCR showed that 213 (55%) strains carried the stx(1) gene, 10 (3%) possessed the stx(2) gene, and 161 (42%) carried both the stx(1) and the stx(2) genes. Enterohemolysin (ehxA) and intimin (eae) virulence genes were detected in 106 (28%) and 23 (6%) of the STEC strains, respectively. The STEC strains belonged to 35 O serogroups and 64 O:H serotypes (including 18 new serotypes). However, 72% were of 1 of the following 12 serotypes: O5:H-, O6:H10, O91:H-, O117:H-, O128:H-, O128:H2, O136:H20, O146:H8, O146:H21, O156:H-, O166:H28, and ONT:H21 (where NT is nontypeable). Although the 384 STEC strains belonged to 95 different seropathotypes (associations between serotypes and virulence genes), 49% of strains belonged to only 11. O91:H- stx(1) stx(2) (54 strains) was the most common seropathotype, followed by O128:H- stx(1) stx(2) (33 strains) and O6:H10 stx(1) (25 strains). Three strains of serotypes O26:H11, O156:H11, and OX177:H11 had intimin type beta1; 5 strains of serotype O157:H7 possessed intimin type gamma1; and 15 strains of serotypes O49:H-, O52:H12, O156:H- (12 strains), and O156:H25 had the new intimin, intimin type zeta. The majority (82%) of ovine STEC strains belonged to serotypes previously found to be associated with human STEC strains, and 51% belonged to serotypes associated with STEC strains isolated from patients with hemolytic-uremic syndrome. Thus, this study confirms that healthy sheep are a major reservoir of STEC strains pathogenic for humans.

Assessment of the doses received by the Cuban population from 40K contained in the body: modelling based on a neural network

Potassium-40 constitutes the main natural source of potassium present in the body, which influences the effective dose received by people. With the aim of assessing the contribution of this component to the doses received by the Cuban population, a study intended to assess the doses was developed. For this purpose, a representative sample of the Cuban population was selected according to age and sex. The measurements were made using the whole-body counter (WBC) of the Center for Radiation Protection and Hygiene (CPHR). For dose estimations, a uniform distribution of potassium for the whole body was assumed. The methodology used was the one recommended by the ICRP. The values of annual effective dose range between 93 and 209 microSv for females and between 123 and 212 microSv for males. The annual average effective dose for members of the public was estimated as 150 +/- 40 microSv, taking into account the experimental data and the specific features of the Cuban population. With the dose values obtained, it was possible to model dose estimates by means of a neural network, which was trained with the results obtained and using as starting data the sex, age, height and corporal weight of people studied. The modelobtained allows consideration of the anatomical features of each person in the estimation of doses.

Predictors of cost of liver transplantation in children: a single center study

OBJECTIVE

Efforts to decrease the cost of orthotopic liver transplantation (OLT) must address the impact of specific interventions on clinical outcome. We hypothesized that an intervention designed to decrease the length of hospitalization would reduce costs without jeopardizing clinical outcome. We further sought to identify predictors of length of stay and cost for hospitalization after liver transplantation.

METHODS

The study group included 47 children who underwent OLT from September 1996 to April 1999, and the control group included 36 children who underwent OLT from March 1994 to August 1996. The intervention was a transition to home program in which patients were discharged to a family living center when they met established clinical criteria and their families met predefined educational goals. We analyzed patients who survived 3 months after OLT.

RESULTS

For the intervention group, the mean length of stay, total costs, and surgical costs were 29%, 36%, and 34% lower, respectively. Organ type, height z score, race, hepatic artery thrombosis, early allograft rejection, and participation in the transition to home program predicted length of stay and total costs.

CONCLUSION

An early discharge program based on defined criteria can be used to decrease length of stay and cost after OLT without jeopardizing clinical outcome.

Study on external exposure doses received by the Cuban population from environmental radiation sources

The results are described of the study carried out with the aim of assessing doses received by the Cuban population due to the external exposure to environmental radiation sources. Contributions of cosmic radiation's ionising and indirectly ionising components to these doses, as well as the fraction resulting from terrestrial radiation, were also assessed as part of this study. Measurements made enabled us to estimate representative effective average doses received by the Cuban population from external exposure to cosmic and terrestrial radiation. Both outdoor and indoor permanency were taken into account for this estimate as well as the distribution of the Cuban population by altitude. The average representative dose due to cosmic radiation was estimated to be 298 +/- 17 microSv per year, while the dose received by terrestrial radiation represented 180 +/- 14 microSv per year, for a total annual dose of 78 +/- 20 microSv. These values are within the range of those reported throughout the world by other authors.

Detection of pap, sfa and afa adhesin-encoding operons in uropathogenic Escherichia coli strains: relationship with expression of adhesins and production of toxins

A total of 243 Escherichia coli strains isolated from patients with urinary tract infections (UTI) were investigated for the presence of pap, sfa and afa adhesin-encoding operons by using the polymerase chain reaction. It was found that 54%, 53% and 2% of the strains exhibited the pap, sfa and afa genotypes, respectively. Pap+ and/or sfa+ strains were more frequent in cases of acute pyelonephritis (94%) than in cases of cystitis (67%) (P < 0.001) and asymptomatic bacteriuria (57%) (P < 0.001). The pap and/or sfa operons were found in 90% of strains expressing mannose-resistant haemagglutination (MRHA) versus 37% of MRHA-negative strains (P < 0.001). The presence of pap and sfa operons was especially significant in strains belonging to MRHA types III (100%) (without P adhesins) and IVa (97%) (expressing the specific Gal-Gal binding typical of P adhesins). Both pap and sfa operons were closely associated with toxigenic E. coli producing alpha-haemolysin (Hly+) and/or the cytotoxic necrotizing factor type 1. There was an apparent correlation between the pap and sfa operons and the O serogroups of the strains. Thus, 93% of strains belonging to O1, O2, O4, O6, O7, O14, O15, O18, O22, O75 and O83 possessed pap and/or sfa operons, versus only 32% of strains belonging to other serogroups (P < 0.001). The results obtained in this study confirm the usefulness of our MRHA typing system for presumptive identification of pathogenic E. coli exhibiting different virulence factors. Thus, 85% of strains that possessed both pap and sfa adhesin-encoding operons showed MRHA types III or IVa previously associated with virulence of E. coli strains that cause UTI and bacteraemia.

Distribution and characterization of faecal verotoxin-producing Escherichia coli (VTEC) isolated from healthy cattle

Faecal swabs obtained from a random sample of 268 cows and 90 calves on 19 Lugo farms were examined for verotoxin-producing Escherichia coli (VTEC). We found VTEC on 95% of the farms. The prevalence rates of VTEC infection in asymptomatic cows and calves were estimated to be 35 and 37%, respectively. The proportion of animals infected on each farm ranged from 0 to 100%. VTEC strains isolated from healthy cattle belonged to 27 O serogroups; however, 57% (85 of 149) were of one of 8 serogroups (O2, O8, O22, O77, O82, O105, O113 and O171). Nearly 60% of the bovine VTEC strains belonged to serogroups that cause haemorrhagic colitis and haemolytic uraemic syndrome in humans. The VTEC were all non-O157:H7; 91% were eae-negative and 86% produced VT2 or VT1 and VT2. These characteristics are different from those of VTEC isolated from calves with diarrhoea.

[Evolution of antidepressive drug consumption in Spain. The impact of selective serotonin re-uptake inhibitors]

BACKGROUND

The pattern of use of antidepressive drugs in Spain through 1985-1994 is studied. Special emphasis is given to the impact of selective serotonin re-uptake inhibitors introduction at the end of the eighties.

MATERIAL AND METHODS

Information on drug utilization was obtained from the databases of the Ministry of Health which contain the number of packages sold in community pharmacies and charged to the National Health System. Data are expressed in defined daily doses (DDD) per 1,000 inhabitants per day.

RESULTS

The use of antidepressants (excluding fixed-dose combinations) increased from 2.7 DDD/1,000 inhabitants/day in 1985 to 9.3 DDD/1,000 inhabitants/day in 1994 (247%). All the subgroups contributed. Selective serotonin re-uptake inhibitors utilization was 4.71 DDD/1,000 inhabitants/day in 1994, representing 71% of the overall increase during the study period. The consumption of fixed-dose combinations decreased in 17%. Since 1991 fluoxetine is the antidepressant most widely used. The consumption through pensioner prescriptions is proportionally higher for second generation antidepressants than for the other groups.

CONCLUSIONS

Antidepressive drugs consumption in Spain increased three times in the last ten years, though it is still below the estimated point prevalence of depression. Selective serotonin re-uptake inhibitors introduction has modified the pattern of use of antidepressants but their impact on the use of the rest of the group has been apparently low.

Prevalence and characteristics of Escherichia coli serotype O157:H7 and other verotoxin-producing E. coli in healthy cattle

From February to July of 1994, 328 faecal samples from 32 herds were collected and verotoxin-producing Escherichia coli (VTEC) found on 84% of the farms. The proportion of animals infected varied from 0-63%. VTEC were recovered from 52 (20%) of 257 cows and from 16 (23%) of 71 calves. Although the VTEC belonged to 25 different serogroups, 7 (O8, O20, O22, O77, O113, O126 and O162) accounted for 46% of strains. Nearly 45% of the strains. Nearly 45% of the 83 bovine VTEC strains belonged to serogroups associated with haemorrhagic colitis and haemolytic uraemic syndrome in humans. However, only 2 (2%) of 83 VTEC strains isolated from cattle belonged to enterohaemorrhagic E. coli (EHEC) serotypes (O26:H11 and O157:H7), and only 8 (10%) were positive for the attaching and effacing E. coli (eae) gene sequence. Polymerase chain reaction (PCR) showed that 17 (20%) of VTEC strains carried VT1 genes, 43 (52%) possessed VT2 genes, and 23 (28%) carried both VT1 and VT2 genes. Characterization of VTEC isolates revelated a heterogeneous population in terms of serogroup and toxin type in the positive herds. This study confirms that healthy cattle are a reservoir of VTEC, but, the absence of eae genes in most bovine VTEC strains suggests that they may be less virulent for humans than eae-positive EHEC.

Virulence factors and O groups of Escherichia coli isolates from patients with acute pyelonephritis, cystitis and asymptomatic bacteriuria

The relationship between the presence of bacterial virulence factors and the severity of urinary tract infection (UTI) was analized in this study. The production of alpha-hemolysin (Hly), the expression of P-fimbriae and the mannose-resistant hemagglutination (MRHA) type IVa (associated with the presence of P-fimbriae), were all detected more frequently in Escherichia coli strains from acute pyelonephritis than in strains isolated from cystitis and asymptomatic bacteriuria. In contrast, the production of cytotoxic necrotizing factor type 1 (CNF1) and the expression of MRHA types III and IVb were distributed uniformly between strains causing different clinical categories of UTI. Thus 88% of the E. coli strains from acute pyelonephritis showed some of the virulence factors investigated in this study, whereas only 60% (p < 0.01) and 56% (p < 0.01) repectively of the strains isolated from cystitis and asymptomatic bacteriuria possessed virulence factors. There were no significant differences in the prevalence of virulence properties between strains isolated from patients with or without complicating factors. Only 16% (p < 0.001) of the fecal isolates from healthy individuals showed virulence factors. The virulence factors were concentrated in strains belonging to 10 (O1, O2, O4, O6, O7, O14, O18, O22, O75 and O83) of the 12 serogroups most frequently detected in uropathogenic E. coli strains. The majority of uropathogenic O4, O6, O14, O22, O75 and O83 E.coli strains were Hly+CNF1+ and expressed P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly+CNF1- and P-fimbriated. Among O1 and O7 strains we found Hly-CNF1-strains that expressed P-fimbriae. Among O2 strains we found Hly+CNF1+ strains that expressed P-fimbriae or MRHA type III and other Hly-CNF1-strains that possessed P-fimbriae. We conclude that E.coli strains isolated from pyelonephritis show virulence factors more frequently than those from cystitis and asymptomatic bacteriuria, and that strains that cause urinary tract infections in Spain belong to the same serogroups as uropathogenic E.coli isolated in other areas of the world. Our results support the special pathogenicity theory and suggest that many cases of serious urogenital disease may be caused by a limited number of P-fimbriated E.coli strains that usually produce alpha-hemolysin.

Prevalence and characteristics of human and bovine verotoxigenic Escherichia coli strains isolated in Galicia (north-western Spain)

An epidemiological study was carried out to determine the incidence and the serotypes of verotoxigenic Escherichia coli (VTEC) that cause infections in Galicia (north-western Spain). Although, VTEC strains were isolated from 55 (14%) of the 387 calves sampled and the majority of bovine VTEC strains belonged to serotypes (026:H11 or H-, 091:H21, O103:H2, 0105:H18, O111:H-O113:H21, O126:H-, O128:H- and O157:H7 or H-) previously associated with human haemorrhagic colitis (HC) and haemolytic uraemic syndrome (HUS) in other countries, VTEC are not a common cause of human infections in Spain. Thus, VTEC (O26:H11 and O86:H10) were isolated from only 3 (0.6%) of the 482 children with diarrhoea investigated. We examined the 69 (3 humans and 66 bovines) VTEC strains that were initially isolated as E. coli producing a toxin cytotoxic to Vero and HeLa cells by polymerase chain reaction (PCR) using specific primers for VT1, VT2 and eae genes. PCR showed that 38 (55%) of VTEC strains carried VT1 genes. 18 (26%) possessed VT2 genes, and 10 (14%) carried both VT1 and VT2 genes. Three (one human and two bovine) strains which were formerly VTEC had lost the ability to produce verotoxins upon subculture and became negative for VT1 and VT2 by PCR. In total 35 (51%) of 69 VTEC strains, including the two human VT1+ strains of serotype O26:H11, were positive for eae sequences when tested by PCR. Presence of the eae gene was significantly more frequent (100%; 21/21) among VTEC strains with serotypes (O26:H11, O111:H-, O157:H-and O157:H7) considered as enterohaemorrhagic E. coli (EHEC) than among VTEC strains with non-EHEC serotypes (29%; 14/48) (p < 0.001). Results obtained in this study indicate that cattle may be an important source of VTEC involved in human disease. However, severe clinical syndromes caused by VTEC, such as HC and HUS, are uncommon in Spain, in comparison with North America and the UK. In any case, VTEC disease can appear on the scene very suddenly, as occurred in the UK and North America in the 1980s.

[Virulence factors and 0 serogroups of Escherichia coli as a cause of community-acquired urinary infections]

BACKGROUND

The aim of this study was to determine the virulence factors and 0 serogroups of E. coli strains that cause community acquired urinary tract infections (UTI).

METHODS

We examined 103 E. coli strains isolated from the urine of patients with UTI. The following virulence factors were investigated using phenotypic techniques: the alpha-haemolysin (Hly), the cytotoxic necrotizing factor type 1 (CNF-1) and the mannose-resistant haemagglutination (MRHA) types III, IVa and IVb expressed by P fimbriated E. coli. Serotyping of 0 antigen was carried out by means of a microtechnique using 163 antisera.

RESULTS

Fifty-five (53%) of the 103 E. coli strains examined showed some of the virulence factors investigated in this study; 41% of the strains were Hly+, 28% were CNF-1+ and 48% expressed MRHA types III, IVa or IVb. The uropathogenic strains characterized belonged to 27 different 0 serogroups. However, 68% were from one of 10 serogroups (01, 02, 04, 06, 09, 018, 027, 073, 075 and 077) and 36% were from one of only 3 serogroups (02, 04 and 06). Furthermore, the virulence factors were concentrated in strains belonging to the 3 serogroups most frequently detected. Thus, 36 (97%) of the 37 strains of these 3 serogroups showed virulence factors, versus only 19 (29%) of 66 belonging to other serogroups (p < 0.001).

CONCLUSIONS

Our results support the special pathogenicity theory and suggest that many cases of community acquired UTI may be caused by a limited number of uropathogenic E. coli strains that produce toxins (Hly+ and/or CNF-1+) and possess P fimbriae or P-related adhesins (with MRHA types III, IVa or IVb), and that usually belong to 02, 04 and 06 serogroups.

Serotypes of CNF1-producing Escherichia coli strains that cause extraintestinal infections in humans

The O:K:H serotypes of 137 necrotoxigenic Escherichia coli (NTEC) producing the cytotoxic necrotizing factor type 1 (CNF1) isolated from human extraintestinal infection were determined. Although NTEC producing CNF1 belonged to 58 different serotypes, only 10 of them accounted for 54% of strains. The most common serotypes, in order of frequency, were: O4:K?:H5, O6:K13:H1, O83:K1:H31, O75:K95:H5, O2:K1:H6, O2:K7:H-, O75:K1:H7, O2:K?:H1, O4:K12:H1 and O22:K13:H1. CNF1 strains of serotypes O2:K7:H- and O4:K12:H1 express P-fimbriae, whereas CNF1 strains of serotypes O2:K?:H1, O2:K1:H6 and O75:K95:H5 possess the adhesin responsible for MRHA type III. Among CNF1 strains of serotype O4:K?:H5 there exist some that express P-fimbriae and others that possess MRHA type III. Lastly, the majority of CNF1 strains of serotypes O6:K13:H1, O22:K13:H1, O75:K1:H7 and O83:K1:H31 do not express P-fimbriae nor the adhesin responsible to MRHA type III. Our results show that extraintestinal infections are caused by a limited number of virulent clones, as suggested by the theory of special pathogenicity.

Virulence factors and O groups of Escherichia coli strains isolated from cultures of blood specimens from urosepsis and non-urosepsis patients

Ninety-six Escherichia coli strains isolated from cultures of blood specimens taken from both urosepsis patients (n = 48) and non-urosepsis patients (n = 48) were examined for the production of alpha-haemolysin (Hly) and cytotoxic necrotizing factor type 1 (CNF1), the expression of P-fimbriae and mannose-resistant haemagglutination (MRHA). Twenty-seven (56%) of the E. coli strains from urosepsis showed some of the virulence factors investigated, whereas only 15 (31%) of the strains associated with non-urosepsis possessed virulence factors (P < 0.05). By contrast, only 16% (P < 0.001) of the faecal isolates from healthy individuals were virulent. Of the bacteremic E. coli strains, 56 (58%) belonged to one of 8 serogroups (O1, O2, O4, O6, O8, O9, O18 and O83). Virulence factors were concentrated in strains belonging to serogroups O2, O4, O6, O18 and O83. Thus, 23 (72%) of the 32 strains of these 5 groups showed virulence factors, but only 19 (30%) of the 64 strains belong to other serogroups (P < 0.001). The majority of bacteremic O2, O4, O6 and O83 E. coli strains were Hly+CNF1+ and expressed P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly+CNF1- and had P-fimbriae or MRHA type III, whereas the strains of serogroup O18 were Hly+CNF1- and had P-fimbriae. We conclude that strains from urosepsis show more virulence factors than bacteremic strains isolated from non-urosepsis.

In vitro action of new organometallic compounds against Trypanosomatidae protozoa

The effects of 10 newly synthesized organometallic rhodium complexes (5 of Rh(I), 4 of Rh(III) and one of Rh(IV) complex salt) and 2 antimony (III) complexes against epimastigote forms of Trypanosoma cruzi and promastigote forms of Leishmania donovani have been studied in vitro. Of the 10 rhodium complexes tested three proved 100% efficient in inhibiting the growth of the epimastigote forms of T. cruzi while only one worked against the promastigote forms of L. donovani. The two antimony complexes inhibited the growth of L. donovani totally and were fairly successful against T. cruzi.

Serotypes and colonization factors of enterotoxigenic Escherichia coli isolated in various countries

One hundred and six enterotoxigenic E. coli (ETEC) isolated from many geographical areas were serotyped and investigated for the presence of colonization factor antigens CFA/I and CFA/II, the expression of mannose-resistant haemagglutination (MRHA) and the levels of surface hydrophobicity. CFA/I was found in 6 (17%) of 36 LT+STa+ strains and in 15 (54%) of 28 STa+ strains; CFA/II was found in 16 (44%) of 36 LT+STa+ strains. None of 42 LT+ strains showed CFA/I or CFA/II. CFA/I was found in ETEC of serotypes O63:K-:H-, O78:K80, O128:K67 and O153:K:H45, whereas CFA/II was found in serotypes O6:H-, O6:K15:H16 and O6:K?:H40. Of the 69 CFA/I- CFA/II- ETEC strains, 9 (13%) showed MRHA with some of the seven erythrocyte species used and 21 (30%) were hydrophobic. Among the 21 hydrophobic strains CFA-negative we have detected: (i) 6 LT+ strains of serogroup O25 negative for MRHA, (ii) 5 strains O159 (4 LT+ and 1 LT+ STa+) also negative for MRHA, and (iii) 3 STa+ strains of serotype O27:K-:H7 that haemagglutinated calf and sheep erythrocytes when grown on Minca-Is. The 106 ETEC strains belonged to 20 different O serogroups. However, 77 (73%) were of one of nine serogroups (O6, O8, O25, O27, O78, O148, O153, O159 and O167). E. coli strains belonging to O6 and O153 groups predominated among ETEC isolated in Spain, O159 strains in the Central African Republic, O25 and O148 strains in Japan, and O15 and O78 strains in India.

Characteristics of haemolytic Escherichia coli with particular reference to production of cytotoxic necrotizing factor type 1 (CNF1)

A total of 1,106 Escherichia coli strains isolated in Spain between 1986 and 1991 from extraintestinal infections and faeces of healthy controls were examined for production of alpha-haemolysin (Hly). Among strains causing urinary tract infections, sepsis and other extraintestinal infections, Hly production was detected in 51% (P < 0.001), 32% (P < 0.001) and 18% (P < 0.02), respectively. In contrast, only 9% of faecal isolates from healthy individuals synthesized Hly. The 356 haemolytic E. coli strains characterized in this study belonged to 28 different serogroups. However, 284 (80%) were of one of eight serogroups (02, 04, 06, 08, 018, 022, 075 and 083); 40% and 31% of haemolytic strains expressed P fimbriae and mannose-resistant haemagglutination (MRHA) type III, respectively. We have found that haemolytic isolates of E. coli may clearly be divided into two categories on the basis of the ability to produce cytotoxic necrotizing factor type 1 (CNF1). The serogroups and adhesins determined in Hly+CNF1+ strains were generally different from those found in Hly+CNF1- strains. Thus, serogroups 02, 06 and 075 were associated with haemolytic E. coli producing CNF1+, whereas serogroups 01, 08, 018, 028 and 086 were established more frequently among Hly+CNF1- strains. While expression of P fimbriae was more frequently detected in Hly+CNF1- strains (70 versus 29%, P < 0.001), MRHA type III was usually identified in Hly+CNF1+ E. coli (42 versus 1%, P < 0.001). Furthermore, the sonic extracts of Hly+CNF1+ strains caused necrosis in rabbit skin (96 versus 25%, P < 0.001) and death in intraperitoneally injected mice (73 versus 11%, P < 0.001) more frequently than sonic extracts of Hly+CNF1- strains.

Establishment of three categories of P-fimbriated Escherichia coli strains that show different toxic phenotypes and belong to particular O serogroups

Eight hundred and nineteen strains of Escherichia coli isolated in Spain between 1986 and 1991 from extraintestinal infections and feces of healthy controls were investigated for expression of P-fimbriae using a particle agglutination test. Among strains causing urinary tract infections, sepsis and other extraintestinal infections, P-fimbriae were found in 31% (130/420) (P < 0.001), 25% (30/118) (P < 0.001) and 12% (11/92) (P < 0.5) respectively. In contrast, only 7% (14/189) of faecal isolates from healthy individuals carried P-fimbriae. According to two more common toxic markers detected in this study (alpha-haemolysin and cytotoxic necrotizing factor type 1), P-fimbriated E. coli strains were grouped into three categories: haemolysin+cytotoxic necrosing factor+ (Hly+CNF1+) (68/185; 37%), haemolysin+cytotoxic necrosing factor- (Hly+CNF1-) (61/185; 33%) and Hly-CNF1- (56/185; 30%). The 185 P-fimbriated strains belonged to 17 different O serogroups. However, 148 (80%) were of one of six serogroups (O1, O2, O4, O6, O7 and O18). The most frequent serogroups determined in the Hly+CNF1+ strains were the O4 and O6 (53/68; 78%), in the Hly+CNF1- strains it was the O18 (27/61; 44%) and in the Hly-CNF1- strains the O1, O2 and O7 (41/56; 73%). The majority (160/185; 86%) of P-fimbriated E. coli expressed the mannose-resistant haemagglutinin type IVa.

Serogroups of Escherichia coli strains producing cytotoxic necrotizing factors CNF1 and CNF2

The serogroups of 396 necrotizing Escherichia coli of human and bovine origin isolated in Spain between 1979 and 1991 have been determined. The 270 cytotoxic necrotizing factor strains belonged to 22 different O serogroups; however, 84% (226 of 270) were of one of seven serogroups (O2, O4, O6, O14, O22, O75 and O83). Although necrotizing E. coli producing cytotoxic necrotizing factor 2 belonged to 28 different serogroups, only six of them (O1, O3, O15, O55, O88 and O123) accounted for 60% (76 of 126) of cytotoxic necrotizing factor 2 strains. Furthermore, only 3% (4 of 126) of cytotoxic necrotizing factor 2 strains belonged to serogroups most common among strains producing cytotoxic necrotizing factor 1. The majority of necrotizing E. coli producing cytotoxic necrotizing factor 1 were obtained from human extraintestinal infections, whereas cytotoxic necrotizing factor 2 strains were isolated from stools of healthy and diarrhoeic calves.

[Escherichia coli virulence factors causing peritonitis, appendicitis and other extraintestinal infections]

Fifty-nine E. coli strains isolated from clinical cases of peritonitis, appendicitis, cholecystitis, wounds and respiratory infections as well as from other miscellaneous sources were investigated. A control group constituted by 475 E. coli strains isolated from the faeces of healthy individuals were also studied. E. coli O-grouped and investigated for production of cytotoxic necrotizing factor CNF1 and alpha-haemolysin (Hly), expression of P fimbriae and mannose-resistant (MRHA) and mannose-sensitive (MSHA) haemagglutination. Virulence factors significantly associated with extraintestinal strains were: production of CNF1 (19% versus 5%, p < 0.001), Hly (27% versus 9%; p < 0.001) and expression of MRHA (44% versus 16%; p < 0.001). The majority of extraintestinal strains (68% versus 36%; p < 0.001), in contrast with faecal E. coli, belonged to O serogroups frequently detected in uropathogenic and bacteraemic E. coli. These results suggest that E. coli causing different types of extraintestinal infections show similar virulence factors and belong to the same serogroups. However, between E. coli isolated from intraabdominal, wound and respiratory infections the number of strains with virulence factors was lower than in E. coli causing urinary tract infections and sepsis.

Enterotoxigenic and necrotizing Escherichia coli in human diarrhoea in Spain

Enterotoxigenic Escherichia coli (ETEC) strains of serotype 0153: K-:H45 CFA/I+ STa+ were associated with two outbreaks of neonatal diarrhoea that occurred in two different hospitals of Madrid, in one of which several children died. Two other outbreaks were associated with ETEC strains of serotypes 0159: K-:H21 (LT+) and 0159: K-:H4 (LT+ STa+) without CFA/I and CFA/II colonization factors. Necrotizing E. coli (NTEC) strains of serotype 06:K13, producing the cytotoxic necrotizing factor CNF1 and alpha-haemolysin, were also associated with two outbreaks of neonatal diarrhoea that occurred in a hospital in Madrid and in a hospital in Talavera de la Reina. The results of the characterization of some ETEC and NTEC strains isolated from sporadic cases of diarrhoea are also discussed.

Enterotoxigenic Escherichia coli associated with infant diarrhoea in Galicia, north-western Spain

To assess the role of enterotoxigenic Escherichia coli (ETEC) in infantile diarrhoea, 482 children with diarrhoea and 103 healthy controls, from three localities of Galicia, north-western Spain, were investigated between 1985 and 1988. Rotavirus (37.3%) and Salmonella spp. (12.8%) were the most common causal agents, followed by ETEC (3.9%), Campylobacter jejuni (2.3%), Shigella spp. (0.9%) and Yersinia enterocolitica (0.5%). ETEC were significantly more frequently isolated from children with diarrhoea who were under 1 month of age (26.5%) than from older diarrhoeic children (2.2%) (p less than 0.001) or from healthy children who were under 1 month of age (0%) (p less than 0.05). Among children who harboured ETEC, five of the nine children under 1 month of age developed diarrhoea in hospital, whereas none of the 10 children over 1 month of age did so. Seventeen ETEC isolates produced heat-stable enterotoxin (STa) only, four produced only heat-labile enterotoxin (LT), and two produced both toxins. Colonisation factor antigens CFA/I and CFA/II were detected in 11 (55.0%) of the 20 ETEC isolates that remained enterotoxigenic after maintenance in the laboratory. Most ETEC isolates belonged to serotypes O153:K-:H45 (nine STa+ CFA/I+ isolates), O27:K-:H7 (three STa+ isolates) or O6:K15:H16 (two LT+ STa+ CFA/II+ isolates). Our results suggest that ETEC constitute an important cause of neonatal diarrhoea in this part of Spain.

Pharmacological and toxicological studies on new Rh(I) organometallic complexes

New rhodium(I) complexes, belonging to the general structure [Rh(CO)2 (L)], where dithiocarbamate and xanthate derivatives, were synthesized and assayed as cytostatic and antitumour agents in vitro against KB cells and in vivo against P388 leukaemia, Ehrlich ascites carcinoma, Sarcoma 180 ascites and ADJ/PC6A solid tumour. Assays against five trypanosoma strains were also performed. Among the new compounds the [Rh(CO)2 (DPA-dtc)] appeared to be active in all biological systems without showing evident nephrotoxicity.

Comparative evaluation of three tests for the detection of Escherichia coli cytotoxic necrotizing factors (CNF1 and CNF2) using filtrates of cultures treated with mitomycin C

Necrotizing Escherichia coli (NTEC) strains grown in the presence of mitomycin C released cell associated necrotizing factors CNF1 and CNF2 to culture medium. Using culture filtrates from 96 mitomycin C treated E. coli strains, we have found that a modified HeLa cell assay was a more sensitive and specific method for the detection of CNF1 and CNF2 than the Vero cell assay and the rabbit skin test.

Virulence factors of bacteraemic Escherichia coli with particular reference to production of cytotoxic necrotising factor (CNF) by P-fimbriate strains

Thirty-seven strains of Escherichia coli isolated from bacteraemia and 40 faecal strains isolated from healthy individuals were O serogrouped and investigated for the production of colicins, haemolysin (Hly), cytotoxic necrotising factor (CNF), lethal activity for mice, the expression of P fimbriae, mannose-resistant (MRHA) and mannose-sensitive (MSHA) haemagglutination, and relative cell surface hydrophobicity. Virulence factors significantly associated with bacteraemic strains were: serogroups O2, O4, O6, O7, O8 and O75 (54% versus 10%, p less than 0.001), production of Hly (32% versus 8%, p less than 0.02) and CNF (38% versus 10%, p less than 0.01), expression of P fimbriae (27% versus 5%, p less than 0.02), MRHA types III, IVa and IVb (51% versus 8%, p less than 0.001), and possession of a moderate cell surface hydrophobic charge (35% versus 13%, p less than 0.05). Virulence factors were strongly associated with strains expressing defined MRHA types. Thus, all strains belonging to MRHA types III and IVa were toxigenic, whereas only 11% of strains belonging to MRHA types IVb, V or VI were toxigenic (p less than 0.001). Virulence factors were concentrated in strains belonging to O serogroups usually found in E. coli that cause extra-intestinal infections, especially in strains of O4 and O6 groups. The most interesting result of this study was that all 12 P-fimbriate strains expressed the MRHA type IVa and 11 of them synthesised CNF.

Enterotoxic, cytotoxic, necrotic and lethal activities in cell-free extracts of Salmonella strains isolated from humans

Unconcentrated cell-free sonic extracts from thirty Salmonella strains isolated from the faeces and blood of humans were investigated for the production of enterotoxins in various tests (Vero cell, infant mouse, rabbit skin permeability and rabbit ileal loop), as well as for lethal activity in adult mice. Sonic extracts from 23 (76.7%) strains were lethal for mice, 21 (70%) increased skin permeability and 3 (10%) showed necrotizing activity for the rabbit skin. No Salmonella strain producing typical Escherichia coli toxins, such as thermolabile (LT) or thermostable (STa) enterotoxins, Verotoxin (VT) or cytotoxic necrotizing factor (CNF) cytotoxins, were detected. Non-repetitive fluid accumulation in rabbit loops was obtained when unconcentrated sonic extracts from 10 selected strains were assayed in seven rabbits. Growth of Salmonella in casamino acid yeast extract medium, followed by treatment of bacterial cells with polymyxin B, was demonstrated to be a rapid and sensitive method for releasing the delayed permeability factor.

Prevalence of enterotoxigenic Escherichia coli strains in outbreaks and sporadic cases of diarrhoea in Spain

Escherichia coli strains isolated 1985-1988 in Spain from patients with diarrhoea were examined; 1170 strains were isolated from 582 sporadic cases of diarrhoea in children, and seven strains were associated with seven outbreaks of diarrhoea. Strains positive for STa enterotoxin production in the infant mouse test were also assayed for production of LT enterotoxin on Vero cells and by a coagglutination test. Thirty-one strains were STa positive: 28 were isolated from 16 (2.7%) sporadic cases of diarrhoea and three were responsible for outbreaks. The majority of STa+LT- strains from both outbreaks and sporadic cases were serotype O153:H45 and expressed the CFA/I colonization factor antigen. Enterotoxigenic STa+LT- strains of serotype O27:H7 and STa+LT+ CFA/II+ strains of serotype O6:K15:H16 were also isolated frequently from sporadic cases.

Toxins and serotypes of faecal non-enterotoxigenic and non-enteropathogenic Escherichia coli strains causing mannose-resistant haemagglutination: relation with haemagglutination patterns

Forty-three faecal non-enterotoxigenic and non-enteropathogenic human Escherichia coli strains causing mannose-resistant haemagglutination (MRHA) were tested for production of cytotoxic necrotizing factor (CNF), haemolysis (Hly), Verotoxin (VT) and lethal activity for mice. The serotypes of the strains were also determined. Of the total strains investigated, 49% synthesized CNF, 53% were haemolytic and 40% were lethal for mice. No strain producing VT was detected. Striking differences in the production of Hly and CNF were observed when MRHA strains were grouped according to their lethal or non-lethal activity. Thus, 82% of lethal strains produced Hly and/or CNF whereas only 35% (p less than 0.01) and 27% (p less than 0.01) of non-lethal strains produced Hly and CNF, respectively. The production of toxins was specially associated with strains possessing defined MRHA types. Thus, 100%, 82% and 50% of strains belonging to MRHA types III, IVa and V, respectively, were toxigenic, whereas no toxigenic strains from MRHA types IVb and VI were detected. The majority (77%) of MRHA strains possessed typical O groups usually reported to be present in pathogenic extraintestinal E. coli or in facultatively enteropathogenic E. coli. Furthermore, these O groups were more frequently detected in toxigenic (93%) than in non-toxigenic (47%) strains (p less than 0.01). Our results suggest that faecal non-enterotoxigenic E. coli strains belonging to MRHA types III, IVa and V may be responsible for extraintestinal infections as well as for sporadic intestinal infections, and that certain O groups are specially associated with E. coli strains belonging to particular MRHA types.