Identification of salmonellae of serogroup C1 by immunofluorescence and co-agglutination with antiserum against an oligosaccharide-protein conjugate.

Antiserum specific for salmonella O7 antigen raised by immunisation of rabbits with an artificial conjugate consisting of oligosaccharide and bovine serum albumin (Os-BSA). The oligosaccharide was a pentasaccharide isolated after cleavage of the O antigen polysaccharide chain of Salmonella thompson (O antigen 6, 7) with endo-glycanase from bacteriophage 14. The usefulness of the S. thompson Os-BSA antiserum for rapid and accurate identification of isolates of Salmonella of serogroup C1 (O6, 7) was shown by indirect immunofluorescence tests in which 77 strains of Salmonella of serogroup C1 were correctly identified from among 848 intestinal strains investigated. The finding that three strains of Escherichia coli and most strains of Candida were also positive in immunofluorescence tests with this antiserum is readily explained by the known structural similarities among the antigenic determinants of E. coli, Candida and Salmonella of serogroup C1. The specificity of the antiserum for the O7 antigen determinant was further demonstrated in enzyme-linked immunosorbent assay tests and in co-agglutination tests with staphylococci sensitised with S. thompson Os-BSA antiserum.

Aetiology and epidemiology of acute gastro-enteritis in Swedish children.

In a prospective 1-year study, 144 children attending or admitted to hospital and 272 children outside hospital with acute gastro-enteritis and 200 controls were investigated by a broad panel of diagnostic methods for enteropathogenic agents in the faeces and for related antibody responses. Enteropathogens were identified in 77% of the inpatients, 63% of the outpatients and 8% of the controls. Rotavirus and Yersinia enterocolitica were detected significantly more often among inpatients. Altogether, viral, bacterial and parasitic agents were found in 58%, 14% and 1% of diarrhoeal patients, respectively. The isolation of more than one pathogenic agent was uncommon (6.5%). Rotavirus (45%) and enteric adenoviruses 40 and 41 (7.9%) predominated among the viruses, while Campylobacter jejuni (4.8%) was most common among the bacteria. Clostridium difficile and/or its cytotoxin, which were found in 14% of the children with gastroenteritis and in 15% of the controls, were significantly associated with antibiotic therapy but not with gastro-intestinal illness. Diarrhoeal infections of unknown aetiology exhibited a seasonal peak in the autumn. The duration of excretion of enteropathogens was investigated. Rotavirus particles were detectable by solid-phase immune electron microscopy for 14-25 days after the diarrhoea had ceased. Transmission of rotavirus and bacterial pathogens within families was studied also.

Studies on enteric campylobacteriosis in Tikur Anbessa and Ethio-Swedish children's hospital, Addis Ababa, Ethiopia.

Between February 1992 and January 1993 different Campylobacter spp. were isolated from 86 (13.7%) of 630 patients with diarrhoea at Tikur Anbessa and Ethio-Swedish Children's Hospital, Addis Ababa, Ethiopia. In the same study population, Shigella spp. were found in 11.7% and Salmonella spp. in 3.8%. Campylobacter spp. were found in all age groups, but the majority were isolated from children less than five years of age (68.6%). Only 2 (0.9%) of 220 controls had campylobacter in their stools. Of the campylobacters that were differentiated at species level, Campylobacter jejuni accounted for 82.4% and Campylobacter coli for 17.6% of the isolates. Yersinia enterocolitica was not isolated from any tested stool specimen. More patients (53.1%) presented for investigation of diarrhoea during the months of April through July than during other parts of the year but there was no significant difference in the frequency of isolation of the three enteric pathogens studied during this period as compared to other months of the year. In 12 of the patients infected with Campylobacter spp., Shigella spp. or Salmonella spp. was concomitantly isolated from their stools. The most common symptoms and signs in both adults and children were watery diarrhoea in 82.4%, low grade fever in 78.4% and frequent vomiting in 45.9%. Dehydration ranging from mild to severe was observed in 25.4% of the 55 children with campylobacter infections. Of the 55 children 67.2% had signs of malnutrition and most of them (47.2%) were underweight. This study indicates that Campylobacter spp. are an important cause of diarrhoea both in adults and children in Addis Ababa, and should be considered routinely in the diagnosis of patients with diarrhoea.

Interchangeability of Hepatitis A boosters, Avaxim and Vaqta, in healthy adults following a primary dose of the combined typhoid/Hepatitis A vaccine Viatim.

This study investigated the suitability of Avaxim and Vaqta as Hepatitis A booster vaccines 6 months after priming with the combined Hepatitis A/typhoid vaccine, Viatim. One hundred and twenty adults were randomly assigned to one of the three groups. Group A (reference group) received Avaxim then Avaxim (n = 40), Group B received Viatim then Avaxim (n = 41) and Group C received Viatim then Vaqta (n = 39). One month after booster vaccination, anti-Hepatitis A virus (anti-HAV) antibodies geometric mean concentrations (GMC) of subjects primed with Viatim were non-inferior to the group primed and boosted with the monovalent Hepatitis A vaccine Avaxim. Anti-Salmonella typhi capsular polysaccharide virulence antigen (anti-Vi) GMCs in groups primed with Viatim were protective and all vaccines were well-tolerated. Therefore, Viatim may be used as a primary HAV vaccine with either Avaxim or Vaqta as Hepatitis A boosters and it will provide the same protection as two doses of Avaxim.

A comparison of the combination pivmecillinam/pivampicillin and co-trimoxazole in the treatment of convalescent carriers of Salmonella and Shigella.

52 convalescent carriers of Salmonellae (n = 25) and Shigellae (n = 27) were treated with a 4-week course of either co-trimoxazole or the combination pivmecillinam/pivampicillin. 84% of the salmonella isolates and 89% of the shigella were resistant to one or more antibiotics. Sulphonamide resistance was observed in 52 and 58% of the strains, respectively. 12 and 44% of the isolates, respectively, were resistant to ampicillin. All were sensitive to mecillinam and all except 2 were sensitive to co-trimoxazole. In salmonella carriers, co-trimoxazole was successful in 54% of the subjects and pivmecillinam/pivampicillin in 58%. Co-trimoxazole cured 83% of the shigella carriers and pivmecillinam/pivampicillin 87%. Shigella carriers responded to therapy promptly. Concurrent biliary disease or diverticulosis adversely affected the prognosis in salmonella carriers.

Pivampicillin/pivmecillinam in the treatment of shigella carriers.

24 patients (4-65 years old; median age 29 years) excreting shigella bacteria greater than 8 weeks were treated with the combination pivampicillin (0.25 g)/pivmecillinam (0.20 g), 2 tablets 3 times a day for 14 days. 23/24 patients (96%) were culture negative after treatment. The one patient that did not respond to treatment carried a strain with intermediate sensitivity to mecillinam and resistance to ampicillin. It is concluded that pivampicillin/pivmecillinam is effective for patients excreting shigella bacteria.

Comparison of micro-ID with API 20E for identification of Salmonella, Shigella and Yersinia species.

Micro-ID is a new kit system for the identification of Enterobacteriaceae in 4 h. It consists of 15 biochemical tests with paper discs. A study was conducted to compare the accuracy of the Micro-ID system with that of the API 20E system for identification of Salmonella, Shigella and Yersinia species. Both systems correctly identified 57 out of 59 (97%) Shigella strains. Micro-ID correctly identified two Salmonella typhi strains, whereas API 20E incorrectly identified one. Of 138 Salmonella strains of other serotypes, 135 (98%) were correctly identified by Micro-ID and 130 (94%) by API 20E. The respective figures for the Yersinia strains were 40 out of 45 (89%) and 30 out of 45 (66%). It is concluded that Micro-ID is at least equal to API 20E in its ability to identify Salmonella, Shigella and Yersinia species.

Asymptomatic urinary tract infection caused by Shigella sonnei.

The first case of asymptomatic urinary tract infection caused by Shigella sonnei in a patient, a 74-yr-old man, who was not a faecal carrier and had no history of dysentery is reported. Treatment with pivmecillinam 400 mg 3 times daily for 14 days was instituted and the bacteria were eradicated. The time and source of infection is unknown.

The immunization of adults against diphtheria in Sweden.

Two hundred and three women who disclaimed vaccination against diphtheria were divided into four groups and injected with either 2.0 or 6.25 Lf of a routine diphtheria toxoid or of a more purified preparation. One hundred and twenty-six of these women who did not show a secondary antibody response were given a second and a third injection one month and one year, respectively, after the first injection. Prebooster (third injection) antitoxin titres of greater than or equal to 0.01 IU ml-1 (the minimum level for protection) were found in 22 and 37% of those who received 2.0 and 6.25 Lf, respectively. Postbooster titres of greater than or equal to 1.0 IU ml-1 (calculated to give a protection of at least ten years of duration) were found in 23 and 58% of those who received 2.0 and 6.25 Lf, respectively. The rate of untoward reactions was low. Fever of short duration occurred in five women. Four out of the five women received 6.25 Lf of the more purified diphtheria toxoid and one 2 Lf of the routine toxoid. Local reactions greater than 10 cm were observed in three women. All received the higher dose, 6.25 Lf of diphtheria toxoid. Local reactions greater than 5 but less than or equal to 10 cm occurred in up to 13% (6.25 Lf of diphtheria toxoid). No significant difference between the groups of women vaccinated with routine or more purified toxoid was found. It was concluded that the diphtheria toxoids in the two doses of 2 Lf and 6.25 Lf did not induce a satisfactory immune response. To induce adequate protection the dose of diphtheria vaccine needs to be the same for adults and children, i.e. 12.5 Lf.

Efficacy of the combination pivampicillin/pivmecillinam compared to placebo in the treatment of convalescent carriers of nontyphi Salmonella.

In a randomized, double blind, placebo-controlled study 36 patients aged 16-77 years who had been carriers of nontyphi Salmonella species for 10-21 weeks were given the combination pivampicillin/pivmecillinam or placebo for four weeks in order to eradicate the carrier state. 34/36 patients who fulfilled the criteria for inclusion in the study were evaluable for efficacy, 16 in the pivampicillin/pivmecillinam group and 18 in the placebo group. Seven patients in the pivampicillin/pivmecillinam group had to terminate the treatment after 10-25 days because of adverse reactions, mainly exanthema and nausea. After therapy 8/16 patients treated with pivampicillin/pivmecillinam and 4/18 patients treated with placebo had negative stool cultures for Salmonella species during a mean follow-up time of 13 and 20 weeks, respectively. No abnormalities could be found in those patients who did not respond to therapy except for earlier cholecystectomy in two patients, both in the pivampicillin/pivmecillinam group.

The serotype distribution of Campylobacter jejuni and C. coli isolated from patients with diarrhoea and controls at Tikur Anbassa Hospital, Addis Ababa, Ethiopia.

Sixty-eight isolates of Campylobacter jejuni and C. coli isolated from patients with diarrhoea (n = 630) and controls (n = 220) at Tikur Anbassa Hospital, Addis Ababa, Ethiopia were serotyped on the basis of the heat-labile (HL) and the heat-stable (HS) antigens, by using 16 and 34 antisera, respectively, for the two methods. With the antisera against heat labile antigens, 89.3% of the C. jejuni and 75% of the C. coli were typable. The HL serotypes 1, 2, 3, 4, 5, 6 and 7 were the most common among the C. jejuni while HL serotypes 1 and 2 were dominant among the C. coli isolates. These serotypes accounted for 63.2% of all isolates. For the heat-stable antigens, 60% of the C. jejuni and 83.3% of the C. coli isolates were typable. The HS serotypes 1, 3, 8, 26 and 34 were most common among the C. jejuni, while serotypes 3 and 8 were dominant among C. coli isolates. This study shows that the most common HL and HS antigens among campylobacter isolates from Ethiopia correspond to the most frequent antigenic types from other parts of the world. A limited number of antisera were sufficient to identify the majority of the isolates.

Specific identification of Salmonella serogroup E antigen O3 by immunofluorescence and coagglutination with antiserum elicited by a synthetic trisaccharide-bovine serum albumin glycoconjugate.

Antiserum specific for Salmonella O3 antigen was raised by immunization of rabbits with an artificial glycoconjugate consisting of the synthetic trisaccharide beta-D- Manp (1----4)-alpha-L- Rhap (1----3)-alpha-D-Galp covalently linked to bovine serum albumin (beta- MRG -BSA). Enzyme immunoassays showed that only lipopolysaccharides extracted from Salmonella serogroup E (O3 antigen-containing) bacteria bound the antiserum. The usefulness of the beta- MRG -BSA antiserum for rapid and accurate identification of Salmonella isolates of serogroup E was shown by indirect immunofluorescence tests in which 50 Salmonella strains of serogroup E 1-4 were correctly identified from among 651 intestinal strains investigated. The finding that one strain of Citrobacter freundii was positive in immunofluorescence tests with this antiserum is readily explained by the known cross-reactivity between some C. freundii strains and Salmonella spp. strains of serogroup E. As expected, the specificity of the antiserum for the O3 antigen could further be demonstrated in coagglutination tests with staphylococci sensitized with beta- MRG -BSA antiserum.

Comparison of Oxoid Signal and biphasic blood culture systems in clinical practice.

The 1-bottle Oxoid Signal blood culture system was compared with a biphasic 2-bottle system in a clinical trial. A total of 851 routine blood samples were processed in the study which was run as a multicenter study at 4 university hospitals. Microorganisms were isolated from 104 (12.2%) blood cultures by one or both methods. 75 (72%) were clinically significant isolates, 61 of them were recovered in both systems, 9 in Oxoid Signal only and 5 in the biphasic system only. 29 isolates (28%) were judged as contaminants, 6 of them were found in both systems, 18 in Oxoid Signal only and 5 in the biphasic system only. The Oxoid Signal System had many advantages although it sometimes gave false positive signals in the device. The growth of pathogens was equally good, 93% versus 88% positive cultures.

Cefamandole nafate: an evaluation of antibacterial activity, serum levels, clinical effect, and incidence of side reactions in 58 patients.

35 males and 23 females with skin and soft tissue infection, lower respiratory tract infection, urinary tract infection or septicemia with known etiology were treated with cefamandole nafate. The patients were to a large extent (30%) alcoholics and/or drug abusers. Cefamandole was given intravenously as 4 daily doses of 1 g in 52 cases and of 2 g in 6 cases for 8 to 16 (mean 10) days. The effect was considered to be good in 40 patients (70%). Adverse reactions, mostly slight and transient, were seen in 22 patients (38%). Peak serum levels varied from 26 to 82 (mean 50) micrograms/ml after 1 g doses and from 68 to 100 micrograms/ml after 2 g. Previous statements of a better in vitro activity of cefamandole than of older cephalosporins against some gram-negative bacilli were corroborated.

Antibody response to Shigella sonnei infection determined by an enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) was developed for determination of the IgA, IgM and IgG antibody responses against a lipopolysaccharide antigen representing Shigella sonnei phase I bacteria. Two or more sera from 33 patients infected with Shigella sonnei were collected during a 12 month period after onset of the disease. Convalescent sera from 56 patients with other enteric infections (salmonellosis, yersiniosis, campylobacteriosis) and sera drawn from 40 healthy blood donors served as controls. Twenty-eight of the 33 patients (85%) had at least one serum specimen where two or three of the immunoglobulin titres were classified as positive (greater than + 2SD above mean titres seen in healthy blood donors), whereas only ten of 56 patients (18%) with other enteric infections had similarly elevated titres (p less than 0.001). The Shigella sonnei ELISA using purified lipopolysaccharide as antigen is considered more sensitive and specific than the formerly used agglutination tests.

Immunoglobulin G (IgG) and IgA subclass pattern of human antibodies to Shigella flexneri and Salmonella serogroup B and D lipopolysaccharide O antigens.

The subclass distribution of human serum antibodies to the O-antigenic lipopolysaccharides of Salmonella serogroups B and D and to Shigella flexneri serotypes 1b, 2a, and 4a lipopolysaccharide antigens were analyzed in an enzyme-linked immunosorbent assay with monoclonal antibodies to the immunoglobulin subclasses. The patients had culture-verified Salmonella (17 Swedes) or Shigella flexneri (23 Vietnamese; 11 children and 12 adults) infections. Consecutive samples drawn during 1 year postinfection were investigated. Antibodies to the Salmonella antigens were mainly of the immunoglobulin G1 (IgG1), IgA1, and IgA2 subclasses. For the Salmonella serogroup B O polysaccharide, the IgA1 and IgA2 subclasses had peak values earlier than (6/9) or coinciding with the IgG1 (3/9) peak value. Furthermore, the IgA2 response to Salmonella serogroup B was positively correlated to the duration of the carrier state (P less than 0.001); the corresponding IgA1 response was less well correlated but was still significant (P less than 0.02). In the case of the Shigella flexneri O polysaccharide, specific antibodies appeared mainly in the IgG1 and IgA1 subclasses. Some IgG2 was also found, surprisingly even in very young patients. No subclass shift with time within the immunoglobulin classes was noted in any of the groups.

Serum IgG antibody responses to Shigella invasion plasmid-coded antigens detected by immunoblot.

Serum IgG antibody responses to Shigella invasion plasmid-coded antigens (Ipa) from 58 Shigella flexneri, S. sonnei, and S. dysenteriae infected Swedish patients were investigated by immunoblot technique. Intense responses to most components of Ipa (Ipas A, B, C, D, and VirG-virulence determinant on SalI fragment G of the plasmid) were evident in sera from S. flexneri infected patients. The strongest response was to Ipa B and the weakest, to Ipa D. In contrast, there were weaker responses to Ipas A, B, C, and VirG but none at all to Ipa D in sera from S. sonnei infected patients. After absorption of the Ipa-positive sera by Ipa expressing strains of S. flexneri and S. sonnei, most IgG antibodies to components of Ipa were removed in sera absorbed by S. flexneri, but IgG antibodies to Ipas--especially to Ipa D--were only slightly reduced in sera absorbed by S. sonnei, suggesting that Ipa D in S. sonnei may not be exposed on the S. sonnei cell surface.

Serum antibody responses against shigella lipopolysaccharides and invasion plasmid-coded antigens in shigella infected Swedish patients.

Serum antibody responses to shigella lipopolysaccharide (LPS) and invasion plasmid-coded antigens (Ipa) were studied in 74 Swedish patients with culture verified bacillary dysentery using class-specific enzyme immunoassay (EIA). Anti-LPS responses were found in 80% and 79% serum samples, respectively, from S. flexneri and S. sonnei infected patients and anti-Ipa responses in 60% and 43%, respectively. The mean anti-Ipa IgG antibody titres in S. flexneri infected patients remained high for 4-6 months after onset while the anti-LPS IgG antibody titres had dropped to normal levels. The specificity of EIA for shigella Ipa was 90% and for S. dysenteriae, S. flexneri and S. sonnei LPSs it varied between 84% and 90%. No close correlations between the anti-LPS and anti-Ipa antibody responses were observed indicating that they may be differently regulated. The dynamics of the serum antibody responses indicates that an anti-LPS response is a good indicator of a recent shigella infection and an anti-Ipa IgG response a good indicator of a previous infection.