Thirty day all-cause mortality in patients with Escherichia coli bacteraemia in England.

Escherichia coli is the commonest cause of bacteraemia in England, with an incidence of 50.7 cases per 100 000 population in 2011. We undertook a large national study to estimate and identify risk factors for 30-day all-cause mortality in E. coli bacteraemia patients. Records for patients with E. coli bacteraemia reported to the English national mandatory surveillance system between 1 July 2011 and 30 June 2012 were linked to death registrations to determine 30-day all-cause mortality. A multivariable regression model was used to identify factors associated with 30-day all-cause mortality. There were 5220 deaths in 28 616 E. coli bacteraemia patients, a mortality rate of 18.2% (95% CI 17.8-18.7%). Three-quarters of deaths occurred within 14 days of specimen collection. Factors independently associated with increased mortality were: age < 1 year or > 44 years; an underlying respiratory or unknown infection focus; ciprofloxacin non-susceptibility; hospital-onset infection or not being admitted; and bacteraemia occurring in the winter. Female gender and a urogenital focus were associated with a reduction in mortality. This is the first national study of mortality among E. coli bacteraemia patients in England. Interventions to reduce mortality need to be multifaceted and include both primary and secondary healthcare providers. Greater awareness of the risk factors for and symptoms of E. coli bacteraemia may prompt earlier diagnosis and treatment. Changes in antimicrobial resistance patterns need to be monitored for their potential impact on infection and mortality.

Fungicidal effect of amphotericin B in urine: in vitro study to assess feasibility of bladder washout for localization of site of candiduria.

An in vitro study was performed to determine the optimum amphotericin B concentration and exposure time required to kill various strains of Candida albicans in urine. This is a preliminary study to assess the feasibility of using amphotericin B bladder washout for localization of the site of candiduria. In broth kinetic killing studies, amphotericin B at a concentration of greater than 100 micrograms/ml produced almost complete killing of 5 x 10(5) CFU of C. albicans per ml within 1.5 to 2 h. In urine studies (with various pH values, osmolalities, and electrolyte concentrations), amphotericin B at a concentration of 200 micrograms/ml with a 2-h exposure time decreased fungal counts of 21 strains of C. albicans from 5 x 10(6) to less than 200 CFU/ml. Bladder washout with greater than or equal to 200 micrograms of amphotericin B per ml and a dwell time of 2 h can therefore sufficiently sterilize the bladder of yeasts and may be a useful localization test.

Comparative clinical efficacy of single oral doses of cefuroxime axetil and amoxicillin in uncomplicated gonococcal infections.

Cefuroxime axetil (1.5 g) was compared with amoxicillin (3 g), both given as a single oral dose combined with probenecid (1 g) for the treatment of uncomplicated gonorrhea. Of 60 evaluable patients receiving amoxicillin, 55 (91.7%) were cured, whereas 55 (96.5%) of the 57 patients receiving cefuroxime axetil were cured (P greater than 0.1). Both drugs were well tolerated.

Three episodes of nosocomial urinary tract infections caused by one O-serotype of Providencia stuartii.

The results of O-serotyping Providencia stuartii isolates in a general hospital showed that 43 isolates were the same serotype (063) and were from 15 patients located in 1 or 2 adjacent wards. On retrospective examination it was found that the series of infections occurred during a 9-month period and could be separated into 3 episodes, involving 7, 6 and 2 patients. All patients who acquired the Providencia stuartii 063 strain were catheterized. The introduction of the strain into the hospital was attributed to a patient catheterized before admission from an institution in which the 063 strain had been identified previously. Antibiotic irrigation was not successful in eliminating Providencia stuartii from the urine and the procedure may be a predisposing factor in preferentially selecting strains of this species.

Immune response in dog. 5 Hyperimmunization with Salmonella typhosa vaccine.

The immune response to Salmonella typhosa during hyperimmunization of dogs and rabbits by intravenous administration, at three different dose levels, three times a week for about seven months, was analysed. The pattern of immune response to both 'H' and 'O' antigen was determined, and antibody activity associated with IgM and IgG was clearly distinguished. Higher levels of both IgM and IgG activity were produced in rabbits than in dogs. The usual pattern of the early onset of IgM synthesis, with subsequent termination of active synthesis while IgG antibody was being formed, was observed in both groups. These results showed that with sufficient stimulation, hyperimmune anti-'O' sera may demonstrate a predominant IgG activity rather than the IgM activity considered to be characteristic of the response to bacterial lipopolysaccharides. Quantitative comparison of the amount of antibody produced to 'O' antigen by the quantitative precipitin method showed that the major differences between the dog and the rabbit remain, with a poorer formation of IgG antibody in the dog. The differences observed between the two species reflect the functioning of an antibody mediated feedback system at a lower threshold in the dog than in the rabbit.

O serotyping of Providencia stuartii isolates collected from twelve hospitals.

A collection of 829 isolates of Providencia stuartii, mostly from urological specimens of patients in 12 hospitals, were O serotyped. Hospitals varied in serotype distribution, but most isolates (97%) fell into one or another of 14 O types of P. stuartii. One type (O63) was found in 10 hospitals, and six types (O4, O17, O25, O52, O55, O56) were found in 5 or more hospitals. These seven types were more common than others and included 753 (91%) of the isolates. Only four isolates agglutinated in Providencia alcalifaciens antisera and, for increased efficiency in serotyping, it is recommended that separate schemes be employed for P. stuartii and P. alcalifaciens. Strains endemic in different hospitals may differ in serotype and give rise to nosocomial infections that are clinically recognizable when infections occur in obvious clusters. Nosocomial infections occurring in low frequency among patients not located close to each other in the hospital may be detected with the aid of serotyping.

Factors influencing the secondary immune response in rabbits to Salmonella typhosa.

The characteristics of the primary response, as well as those of the secondary response, to different doses of Salmonella typhosa when elicited at two different time intervals were analysed. The antibody response demonstrates that the size of the primary dose, and the size of the secondary dose, have significant effect on the subsequent synthesis of the secondary IgM and IgG antibody response to both 'H' and 'O' antigens. The time elapsed between the primary and secondary response tends to decrease the IgG response. Due to the high immunogenicity of the 'H' antigen the maximum IgG levels were reached within the range of doses used. These high levels of antibody inhibited the secondary IgM response by a feedback mechanism. Enhanced or equivalent response of predominant anti 'O' IgM system was recorded.

Production of complete and incomplete antibodies to human red blood cells in dogs and rabbits.

The characteristics of the immune response of dogs and rabbits to single and multiple injections of human red blood cells were analysed. The results show that the primary and secondary response of both species are essentially the same. Following repeated stimulation with this antigen quantitative differences of the immune response between these animals were observed. The rabbit produced substantially greater amounts of IgG complete and incomplete antibody, and proportionally greater amounts of IgM antibody, whereas the dog response was seen to be inhibited.

Nosocomial urinary tract infections caused by two O-serotypes of Providencia stuartii in one hospital.

Providencia stuartii nosocomial urinary tract infections occurring in the same hospital over an 18-month period of retrospective study were shown, by serotyping and biotyping, to have been caused by two endemic strains. Two episodes, involving 38 patients in one ward and 11 patients in another, were caused by a mannitol-positive strain of serotype O55. Transmission of the strain through the movements of one patient appeared to have been the basis for the introduction of the agent from one ward to the other. In another episode, involving two patients in a third ward, the infections were caused by a mannitol-negative strain of serotype O49. The study demonstrated the usefulness of serotyping and biotyping in epidemiological studies of infections caused by P. stuartii.

Variation in urease activity of endemic hospital strains of Proteus rettgeri and Providencia stuartii.

Both urease-positive and urease-negative Proteeae isolated from cross-infected patients in the same hospitals and, in three cases, from the same patients were examined for their biochemical reactions and somatic (O-) antigens. All isolates gave the same reactions in 17 biochemical tests and possessed O-antigens characteristic of Providenic O-type strains 4 or 17. Study of the isolates indicated that endemic strains are capable of undergoing variation in urease activity. In the current classification urease-positive and urease-negative strains are classified as Proteus rettgeri and Providencia stuartii, respectively. The observed variation in urease activity of nosocomial isolates of Proteeae suggests that taxonomy should be modified so that all such strains would be accommodated in a single group.

Preparation of typing antisera specific for O antigens of Pseudomonas aeruginosa.

Results of serotyping 966 clinical isolates of Pseudomonas aeruginosa showed that 72% agglutinated specifically in one or another of the 16 typing antisera, but 28% agglutinated in two or more and often in as many as 10 antisera; this polyagglutinability correlated with a high incidence of cross-reactivity among the antisera. Absorption of each typing antiserum with either cell suspensions of five O-type strains or with a suspension of a particular polyagglutinable strain (SMC 247) abolished cross-reactivity in the typing antisera without significantly reducing titers against the homologous strains. All but four of the polyagglutinable strains agglutinated specifically in one or another absorbed antisera. The cross-reactions of unabsorbed antisera were interpreted to have been caused by antibodies directed not against specific O antigens but against thermostable specificities that remain undefined.

Evaluation of a Proteus rettgeri O-serotyping system for epidemiological investigation.

An evaluation of the serotyping system for Proteus rettgeri has been performed through its application to 561 human isolates of this species. Of these, 545 were typable and could be separated into 58 O serotypes. A group of isolates from one hospital, and clinically implicated in cross-infections, was found to belong the same O serotype, confirming the clinical findings. Isolates with more than one specificity of thermostable antigen, in most cases, were found to have combinations of such specificities restricted to combinations previously defined for the O-type strains. Furthermore, the use of pooled antisera was investigated and system of pooling was devised to retain the specificity of the system and to increase the facility of the typing procedure.

Reconstitution of the somatic (O-) antigenic scheme for Providencia and preparation of O-typing antisera.

The somatic (O-) antigens of the type strains of the providencia antigenic scheme were examined for their biochemical reactions and their O-specificities. The scheme of 62 O-antigens was reconstituted from 52 original type strains and 10 strains substituted for originals that either were biochemically atypical of the genus or showed inappropriate serological reactions. Thirty-six type strains showed no significant relations with other type strains, and antisera could be used for typing without absorption. Among 26 type strains, significant reciprocal relations were demonstrated, and each cross-reacting antigen was examined for specificity and for its distribution among the type strains. Antisera to these strains required absorption with cell suspensions of other type strains for production of specificity in O-typing. Each typing antiserum, at low dilution, was shown to agglutinate homologous, but not heterologous, cell suspensions of type strains, and this result demonstrated the required specificity for typing on the basis of the O-antigens.

Immune response in dog. 3. Antibody formation in dogs and rabbits to human serum proteins and keyhole limpet haemocyanin.

Antibody formation in dogs and rabbits to human serum proteins and keyhole limpet haemocyanin (KLH) following primary, secondary and multiple stimulation was analysed. Primary injection of human serum stimulates the formation of precipitin antibodies to beta2 lipoprotein in dogs, beta2 lipoprotein and beta globulin in rabbits. After a secondary dose the rabbits formed precipitins to a whole range of human serum proteins, while the dogs to beta2 lipoprotein, albumin, beta globulin. When the primary dose of antigen was divided over a period of 8 weeks, the dog produced precipitins to beta2 lipoprotein while the rabbit to a wide range of serum proteins. Secondary stimulation of these animals did not increase the number of precipitins formed. Quantitative analysis of the antibody produced show that the best response was with beta2 lipoprotein followed by albumin and beta globulin. As the immunogenicity of the antigen was greater the differences between the two species were narrow. These differences were less pronounced following the primary injection than after the secondary and multiple stimulations. The primary response to KLH (which represents mainly IgM) is better in the dog than in the rabbit, while the secondary response (IgG) was better in the rabbit. The poorer IgG response in the dog compared to the rabbit, observed in all the experiments, is discussed.

Immune response in dog 2 effect of dose of antigen on antibody production.

The primary antibody response of dogs and rabbits to both 'H' and 'O' antigens of Salmonella typhosa following intravenous injection with a formalin killed vaccine from 2.4 x 10(6) to 2.4 x 10(10) organisms/kg body weight was analysed. The animals were restimulated 80 days later with various vaccine concentrations. The lgM anti-'O' and lgG anti-'H' and 'O' antigens in the dogs, were significantly weaker in both primary and secondary response than the comparable rabbit group. Primary lgM anti-'H' response in the dog was found to be greater, equal, or less than that observed in the rabbit. A closer analysis of the primary response indicated that both animal species show the same latent period and doubling time in respect of anti-'H', and the differences observed are probably the result of the number of progenitor cells stimulated by the antigen. On the other hand the suppressed response of the dog to 'O'-antigen is the result of an overall weaker response of this animal to the antigen. The secondary anti-'H' lgM response was found to be greater than, equal to, or less than the primary response in the same animal. The significant inhibition of this response was observed in those animals which received a high primary dose of antigen.

Biotypes of Proteus rettgeri.

Examination of 729 isolates of Proteus rettgeri showed that 674 reacted positively in tests for phenylalanine deamination, indole production, growth on citrate, and acid production from meso-inositol, and negatively for L-ornithine decarboxylation and acid production from lactose, maltose, D-xylose, and L-arabinose. Only 51 isolates differed in one, and four differed in two of these ten reactions, which were taken as the core characteristics of the species. On the basis of additional tests (acid production from salicin, L-rhamnose, D-mannitol, adonitol, and D-arabitol), the 729 isolates could be separated into five groups. Goups 1, 2, 3, and 4 could be further separated on the basis of the reaction with meso-erythritol, and group 5 could be subdivided on the basis of reaction with D-mannitol. Two metabolically distinct kinds of P. rettgeri were recognized. Isolates of the first kind (groups 1, 2, 3, and 4) each utilized both adonitol and D-arabitol and most utilized meso-erythritol. Isolates of the other kind (group 5) were negative with the three polyhydric alcohols but resembled, in their reactions, some strains of Providencia stuartii. These may be intermediates between P. rettgeri that catabolize these substrates and the Providencia.