HOST-PARASITE INTERACTION IN PATIENTS WITH INFECTIONS DUE TO ESCHERICHIA COLI. I. THE SEROGROUPING OF E. COLI FROM INTESTINAL AND EXTRAINTESTINAL SOURCES

Escherichia coli B2 Phylogenetic Subgroups in the Infant Gut Microbiota: Predominance of Uropathogenic Lineages in Swedish Infants and Enteropathogenic Lineages in Pakistani Infants

Escherichia coli segregates into phylogenetic groups, with group B2 containing both extraintestinal pathogenic E. coli (ExPEC) and enteropathogenic E. coli (EPEC) strains. Ten main B2 subgroups (subgroups I to X)/sequence type complexes (STcs), as well as EPEC lineages, have been identified. In the current study, we characterized ExPEC and EPEC strains of E. coli B2 phylogenetic subgroups/STcs that colonize Swedish and Pakistani infants. Gut commensal E. coli B2 strains, 120 from Swedish infants (n = 87) and 19 from Pakistani infants (n = 12), were assigned to B2 subgroups. Carriage of the bundle-forming pili and intimin adhesin was examined in the EPEC lineages. The ExPEC virulence markers and the time of persistence of the strains in the microbiota were previously determined. In total, 84% of the Swedish strains and 47% of the Pakistani strains belonged to 1 of the 10 main B2 subgroups (P = 0.001). Among the Swedish strains, the most common B2 subgroups were IX/STc95 (19%), II/STc73 (17%), VI/STc12 (13%), and III/STc127 (11%), with each subgroup carrying distinctive sets of ExPEC virulence markers. EPEC lineages with few ExPEC features constituted 47% of the Pakistani B2 strains but only 7% of the Swedish B2 strains (P = 0.0001). The subgroup distribution within phylogenetic group B2 strains colonizing the gut differed between Swedish and Pakistani infants. B2 subgroups with uropathogenic characteristics dominated the gut microbiota of Swedish infants, while EPEC lineage 1 strains frequently colonized the intestines of Pakistani infants. Moreover, within the B2 subgroups, ExPEC virulence genes were more prevalent in Swedish strains than in Pakistani strains. Thus, ExPEC traits exemplify the intestinal B2 strains from Western populations.IMPORTANCE The intestinal microbiota is an important reservoir for bacteria that cause extraintestinal infections. Escherichia coli is found ubiquitously in the gut microbiota, and it also causes urinary tract infections, infantile septicemia, and meningitis. Urinary tract infections are usually caused by E. coli strains that originate in the intestinal microbiota. E. coli also causes gastrointestinal infections and is a major cause of diarrhea in infants worldwide. The abilities of certain E. coli strains to cause infections are attributed to their virulence factors, i.e., bacterial components that contribute to the development of different diseases. Our study shows that different subtypes of potentially pathogenic E. coli strains dominate in the gut microbiota of infants in different geographical areas and expands our knowledge of the interplay between bacterial commensalism and pathogenicity.

Predictors and risk factors for the intestinal shedding of Escherichia coli O157 among working donkeys (Equus asinus) in Nigeria

OBJECTIVES

Escherichia coli are an important group of bacteria in the normal gastrointestinal system but can sometimes cause infections in domestic animals and man. Donkeys are routinely used as multipurpose animal but details of burdens of potentially infectious bacteria associated with it are limited. The prevalence and associations between intestinal shedding of E. coli O157 and animal characteristics and management factors were studied among 240 randomly selected working donkeys in north-western Nigeria.

DESIGN

Four local government areas, of Sokoto State in north-western Nigeria were recruited in this study. A multistage randomised cluster design was used to select subjects and donkey owners within selected zones. Confirmation of infection was based on bacterial culture, isolation and biochemical test for E. coli O157 from faecal samples.

RESULTS

Of the total bacteria isolated, 203 of the 329 (61.70 per cent) were E. coli, 76 of which was E. coli serotype O157. A multivariable logistic regression model was used to examine the relation between intestinal shedding of E. coli O157 and selected variables. The analysis yielded five potential predictors of shedding: soft faeces in donkeys, Akaza and Fari ecotypes of donkey were positive predictors while maize straw as feed and sampling during the cold dry period were negative predictors.

CONCLUSIONS

This study concludes that controlling intestinal shedding of E. coli O157 among working donkeys in Nigeria is possible using the identified predictors in planning appropriate interventions to reduced human risk of infection.

A prospective, longitudinal study of the behavior of serologically classified isolates of Escherichia coli in women with recurrent urinary tract infections

OBJECTIVE

This study characterizes further the behavior of serologically classified isolates of Escherichia coli in women with recurrent urinary tract infections (UTIs).

METHODS

A prospective, longitudinal study of 203 young to middle-aged women with UTIs was conducted. Seven hundred and sixty-one UTIs due to E. coli were identified in the 203 women during observation periods of 1.1-19.4 years. Isolates from urine were routinely serologically classified. Clusters of UTIs and rates per year of infections with the same serogroup were defined to quantify further UTIs.

RESULTS

One hundred and forty-eight (73%) of the 203 women experienced 2-42 UTIs with E. coli. Fifteen percent of recurrences occurred within 1 month of the previous infection; 57%, 6 months; and 70%, 1 year. During the first four months, recurrences with the same serogroup accounted for 81-50% of recurrences; thereafter, recurrences with a different serogroup were more frequent. Clusters of UTIs occurred in 52% of the 148 women and ranged in size from 2-5 infections. Multiple recurrences with the same serogroup were more frequently caused by a few common serogroups.

CONCLUSIONS

Isolates of a few common serogroups of E. coli were associated with the great majority of both index and recurrent UTIs. Some isolates of both common and less common serogroups were associated with multiple recurrences with the same serogroup. The wide range in rates/year among recurrences with isolates of different serogroups in individual women were consistent with the hypothesis that these differences were more likely to be due to differences in virulence of the isolates than to host factors.

Infections of the urinary tract in women: a prospective, longitudinal study of 235 women observed for 1-19 years

A prospective long-term study was conducted of 235 young to middle-aged women with past histories of and/or active infections of the urinary tract. The present report defines certain characteristics of the population and of the 1,018 confirmed infections of the urinary tract that occurred during observation periods ranging from 1.1 to 19.4 years (mean, 7.4 yr). The population could be divided into 3 groups: women with confirmed infections who did (Group 1, n = 19) or did not (Group 2, n = 191) receive courses of antimicrobial prophylaxis and those who did not have confirmed infections (Group 3, n = 25). The 3 groups differed significantly only in their mean infection rates per year (3.1, 0.8, and 0.0, respectively). The number of infections among individual women ranged from 0 to 42. The patterns of recurrent infections among individual women ranged widely and were not predictable. Clusters of infections occurred in 45.7% of the women and ranged in size from 2 to 12 infections per cluster. The proportions of different infecting organisms and clinical syndromes were similar to those reported by others. accounted for the great majority of infections. Eighty-five percent of the isolates of tested were serologically classified. A total of 50 different O groups were identified. Three (O4, O6, and O75) of the 131 potential O groups accounted for 49% of the isolates that could be classified. In each of the 4 clinical syndromes, these same 3 O groups were also the most frequently identified. The ability to classify serologically the infecting isolates of permitted a more complete definition of the complexity of patterns of recurrent infections among individual women. The findings in the present study are compared with those in the literature.

Surfactant-like particles mediate tissue-specific functions in epithelial cells

Lipid-rich, unilamellar membranes appear to be relatively common structures lining the apical or 'exposed' surface of epithelial cells. They have now been described in the intestinal tract from the esophagus to the rectum and have been isolated from tissues, such as the stomach, the small bowel, the colon, and the bladder. The presence of a lining layer in the lungs has been known for some time, and its functions, structure, and metabolism have been extensively studied, as can be gleaned from the multitude of reports presented at this symposium. The 'other' surfactants, however, have attracted far less attention and have been investigated in detail in only a few reports. This paucity of information, when compared to the pulmonary system, is most likely due to the fact that a generalized function (sufficiency state) or disease (deficiency state) has not yet been recognized for either the intestinal or urinary forms of surfactant. It seems reasonable to assume that the role of the SLP will vary, at least in part, with the organ or tissue with which it is associated, although the widespread nature of the membrane assumes that some functions (e.g. protective) will be shared. Thus, pulmonary surfactant's primary function in the lung may be to reduce surface tension and prevent lung collapse; but it also plays a significant part in the lung's defenses against bacterial and/or chemical invasion. It is hoped that future studies will shed some light on the function of the various SLPs and lead to a better appreciation for their role in both maintaining a healthy environment and contributing to the proper functioning of their host tissues.

H-NS controls pap and daa fimbrial transcription in Escherichia coli in response to multiple environmental cues

A comparative study was completed to determine the influence of various environmental stimuli on the transcription of three different fimbrial operons in Escherichia coli and to determine the role of the histone-like protein H-NS in this environmental regulation. The fimbrial operons studied included the pap operon, which encodes pyelonephritis-associated pili (P pili), the daa operon, which encodes F1845 fimbriae, and the fan operon, which encodes K99 fimbriae. Using lacZYA transcriptional fusions within each of the fimbrial operons, we tested temperature, osmolarity, carbon source, rich medium, oxygen levels, pH, amino acids, solid medium, and iron concentration for their effects on fimbrial gene expression. Low temperature, high osmolarity, glucose as a carbon source, and rich medium repressed transcription of all three operons. High iron did not alter transcription of any of the operons tested, whereas the remaining stimuli had effects on individual operons. For the pap and daa operons, introduction of the hns651 mutation relieved the repression, either fully or partially, due to low temperature, glucose as a carbon source, rich medium, and high osmolarity. Taken together, these data indicate that there are common environmental cues that regulate fimbrial transcription in E. coli and that H-NS is an important environmental regulator for fimbrial transcription in response to several stimuli.

Role of intestinal surfactant-like particles as a potential reservoir of uropathogenic Escherichia coli

The binding of uropathogenic Escherichia coli is mediated at the tips of pili by the PapG adhesin, which recognizes the Galalpha(1-4)Gal disaccharide on the uroepithelial surface. These receptors have been identified unequivocally in the human and murine urinary tracts but not in intestinal epithelium, yet uropathogenic E. coli strains are commonly found in normal colonic microflora. The gastrointestinal tract from duodenum to rectum elaborates a phospholipid-rich membrane particle with surfactant-like properties. In these studies, we report that purified murine particles contain a receptor recognized by the class I PapG adhesin because: (1) PapD-PapG complexes and class I pili bound to surfactant-like particles in a solid-phase assay, whereas binding was not detected in microvillous membranes derived from the same tissues, (2) purified PapD-PapG complex bound to a glycolipid receptor detectable in lipid extracts from the particles, and (3) soluble Galalpha(1-4)Gal inhibited the adhesin by 72% from binding to surfactant-like particles. The Galalpha(1-4)Gal receptor present in the intestinal surfactant-like particle which overlies the intestinal mucosa could provide one means to establish an intestinal habitat for uropathogenic E. coli.

Binding of pili from uropathogenic Escherichia coli to membranes secreted by human colonocytes and enterocytes

PapG adhesins mediate the binding of uropathogenic Escherichia coli. Although receptors for these adhesins have not been demonstrated in intestinal epithelia, the colonic microflora includes strains of uropathogenic E. coli. We now report that surfactant-like particles secreted by the human intestine contain receptors for PapG adhesins and may provide an intestinal habitat for uropathogenic bacteria.

The PapG-adhesin at the tip of P-fimbriae provides Escherichia coli with a competitive edge in experimental bladder infections of cynomolgus monkeys

Human urinary tract infection is an infectious disease that depends on a series of host-microbial interactions. The bacteria first colonize the colon and then the periurethral/vaginal areas; they ascend to and infect first the bladder and then the kidneys. Expression of Escherichia coli P-fimbriae constitutes the strongest correlation to renal pathogenicity, but is also related to first-time cystitis in children. The role of P-fimbriae in the preceding steps in the infectious process is unknown. To examine this, we constructed, from a P-fimbriated E. coli strain with a class II G-adhesin preferentially binding to globoside, one isogenic mutant lacking the G-adhesin and another isogenic mutant in which we replaced the papG class II allele with a class III adhesin preferentially binding to the Forssman antigen. We report here the comparison of the adhesin knockout mutant (DS17-8) and the class-switch mutant (DS17-1) with the wild-type (DS17) for in vivo colonization of the gut, vagina, and bladder of cynomolgus monkeys. It was recently shown that the class II tip G-adhesin is a prerequisite for acute pyelonephritis to occur in the monkey model in the absence of other kidney-specific adhesins or obstruction of the urinary flow. Here we show that it is not required for bladder infection but gives a competitive advantage in mixed infections. In the vagina and colon, the G-adhesin gives no competitive advantage.

Loss of the O4 antigen moiety from the lipopolysaccharide of an extraintestinal isolate of Escherichia coli has only minor effects on serum sensitivity and virulence in vivo

The O-specific antigen in extraintestinal isolates of Escherichia coli is believed to be an important virulence factor. To assess its role in the pathogenic process, proven isogenic derivatives with either a complete (CP921) or nearly complete (CP920) deficiency of the O4 antigen were obtained by TnphoA'1-mediated transposon mutagenesis of an O4/K54/H5 blood isolate (CP9). By utilizing a previously reported isogenic K54 capsule-deficient derivative (CP9.137), additional isogenic derivatives deficient in both the K54 capsular antigen and either all (CP923) or nearly all (CP922) of the O4 antigen were also constructed. These strains and their wild-type parent were evaluated in vitro for serum sensitivity and in vivo by intraperitoneal challenge of outbred mice. The complete or nearly complete loss of the O4 antigen (CP920 and CP921) resulted in only a minor increase in serum sensitivity. In contrast, CP9.137 had a significant increase in serum sensitivity, and CP922 and CP923 were extremely serum sensitive. When tested in vivo, the complete or nearly complete loss of the O4 antigen resulted in a small but significant increase (P < or = 0.05), not the expected decrease, in virulence compared with its wild-type parent. In contrast, CP9.137 and CP922 were significantly less virulent (P < or = 0.05). These studies do not exclude a role for the O4 antigen moiety of lipopolysaccharide in the pathogenesis of extraintestinal E. coli infection; however, they demonstrate that the O4 antigen plays only a minor role in serum resistance in vitro and that its loss does not diminish and perhaps enhances the virulence of CP9 in vivo after intraperitoneal challenge.

Molecular epidemiology of catheter-associated bacteriuria in nursing home patients

Urine samples from 19 nursing home patients with long-term urinary catheters were cultured every 3 months for 18 months. Providencia stuartii, present in 74% of the elderly and in 59% of urine specimens, was the most frequently isolated bacteria. The persistence of P. stuartii was significantly higher among females than among males. In order to study the epidemiology of bacteriuria in this nursing home, bacteria were characterized by biochemical tests, antibiotic susceptibility pattern, and restriction fragment length polymorphism (RFLP) analysis. The antibiotic susceptibility pattern indicated that each patient had two to three different strains of P. stuartii during the 18 months of follow-up. In contrast, the RFLP analysis revealed that a specific strain had persisted in the urinary tract of the patient during the entire follow-up period. According to the biochemical profile, 74% of the patients had the same bacteria in urine cultures, pointing to a common source of transmission. RFLP analysis, however, demonstrated different patterns of RFLP, suggesting concomitant multiple sources of infection.

Ribotyping differentiates relapse from reinfection in the treatment failures of Escherichia coli urinary tract infections in children

Analysis of restriction fragment-length polymorphism of ribosomal DNA regions (ribotypes) was used as an epidemiologic tool to compare 25 pre- and posttreatment strains obtained from 12 patients treated with either cefpodoxime proxetil or amoxicillin-clavulanic acid. Ribotyping is a promising method to differentiate relapse from reinfection in the treatment failures of Escherichia coli urinary tract infections.

History of recognition and measurement of colonization resistance of the digestive tract as an introduction to selective gastrointestinal decontamination

Selective decontamination of the digestive tract was developed following the observation that the digestive tract normally has considerable resistance to colonization by newly ingested bacteria. The research that eventually led to selective decontamination was performed because in the late 1960s and early 1970s, the need for prophylaxis against Gram-negative infections in immuno-compromized patients became evident. At that time, the relatively small number of antibiotics available for therapy of serious infections often lead to treatment failure. To introduce the subject of selective decontamination, this paper, therefore, starts with a short historical overview of the kind of infectious agents as well as the antibiotics available in the 1960s; particularly regarding the type and treatment of infections in severely compromised patients. The fact that the possibilities in infectious diseases were limited was the reason for our experimental search for ways of successful prophylactic treatment with minimal risk of development of resistance.

Horizontal gene transfer of the Escherichia coli pap and prs pili operons as a mechanism for the development of tissue-specific adhesive properties

Escherichia coli strains bind to Gal alpha 1-4Gal-containing glycolipids via P pili-associated G-adhesins. Three functional classes of adhesins with different binding specificities are encoded by conserved G-alleles. We suggest that the Class I papG-allele of strain J96 is a novel acquisition possibly introduced via horizontal gene transfer into one of the two P pili gene clusters carried by this strain. Closely related strains in the ECOR collection of natural E. coli isolates carry either a Class II or a Class III G-adhesin. Data indicate that genetic exchanges involving either entire pap or prs gene clusters or individual pap/prs genes have occurred. We propose that the retention and spread of pap/prs DNA among E. coli is the result of selection pressure exerted by mammalian intestinal isoreceptors.

The importance of P and type 1 fimbriae for the persistence of Escherichia coli in the human gut

The faecal Escherichia coli flora was studied in 89 infants. Each infant was followed with a mean of 12 faecal samples (range 5-21) between 0 and 18 months of age. All isolates were assayed for P fimbriae and biochemically phenotyped and the persistence of each strain (phenotype) in the infant's gut was determined. In a subset of strains the occurrence of type 1 fimbriae and adherence to HeLa cells was studied. Thirty-one per cent of isolates belonging to strains colonizing for longer than 6 months expressed P fimbriae compared to 19% of the isolates from strains colonizing 1-6 months or transient strains colonizing less than 1 month. Type 1 fimbriae and adherence to HeLa cells occurred similarly often in all groups of strains. We conclude that P fimbriae, but not type 1 fimbriae or HeLa cell adherence seemed to contribute to the ability of the E. coli strain to colonize the human intestine.

A theoretical and experimental analysis of bacterial growth in the bladder

A mathematical model of human micturition dynamics and bacterial growth predicts the population growth rate required for a bladder infection to become established in the absence of adhesin-mediated surface growth. Escherichia coli strains isolated from the urinary tract have significantly higher in vitro growth rates in urine than strains isolated from the intestinal flora. The results suggest that, for E. coli isolated from the urinary tract, adhesin-mediated surface growth may not be required for infections to become established and persist. The growth-rate differences observed between urinary tract and intestinal isolates suggests that the ability to survive and efficiently utilize the resources available in urine is an important adaptation for E. coli inhabiting the urinary tract.

Virulence characteristics of male genital tract Escherichia coli isolated from semen of suspected infertile men

The role of Escherichia coli isolates from the semen in the etiology of male infertility, was investigated in this study. Several possible virulence factors of E. coli, such as possession of O antigens or certain K antigens (K1, K5), the type of fimbriae, resistance to antimicrobial drugs and adherence studies to various mammalian sperm cells were examined. It was found that out of 181 E. coli isolates 76.4% belonged to four different urinary serotypes: O1, O2, O4 and O6 (5.7%, 7.5%, 17.0% and 46.2%, respectively). The predominant fimbrial phenotype (81.2%) was T1F+/P-, while 15.8% showed also the possession of P fimbriae (T1F+/P+). No isolate was found with the T1F-/P+ phenotype. The possession of antigens K1, K5 was found to be low (12% only). A relatively high level of adherence to different mammalian sperm cells was found among E. coli isolates. 43% of the E. coli isolates were resistant to doxycycline (the drug of choice) and additionally, most of these were resistant also to ampicillin. We suggest that there is a close subpopulation of E. coli which possess certain virulence properties and have the potential to adhere to sperm cells and to colonize on other target tissues in the male genital tract. Such virulent may cause asymptomatic male infertility and may be termed male genital tract (MGT)-E. coli.

Virulence factors in Escherichia coli urinary tract infection

Uropathogenic strains of Escherichia coli are characterized by the expression of distinctive bacterial properties, products, or structures referred to as virulence factors because they help the organism overcome host defenses and colonize or invade the urinary tract. Virulence factors of recognized importance in the pathogenesis of urinary tract infection (UTI) include adhesins (P fimbriae, certain other mannose-resistant adhesins, and type 1 fimbriae), the aerobactin system, hemolysin, K capsule, and resistance to serum killing. This review summarizes the virtual explosion of information regarding the epidemiology, biochemistry, mechanisms of action, and genetic basis of these urovirulence factors that has occurred in the past decade and identifies areas in need of further study. Virulence factor expression is more common among certain genetically related groups of E. coli which constitute virulent clones within the larger E. coli population. In general, the more virulence factors a strain expresses, the more severe an infection it is able to cause. Certain virulence factors specifically favor the development of pyelonephritis, others favor cystitis, and others favor asymptomatic bacteriuria. The currently defined virulence factors clearly contribute to the virulence of wild-type strains but are usually insufficient in themselves to transform an avirulent organism into a pathogen, demonstrating that other as-yet-undefined virulence properties await discovery. Virulence factor testing is a useful epidemiological and research tool but as yet has no defined clinical role. Immunological and biochemical anti-virulence factor interventions are effective in animal models of UTI and hold promise for the prevention of UTI in humans.

Bacterial adherence as a virulence factor in urinary tract infection

Escherichia coli (E. coli) causes greater than 90% of urinary tract infections, UTI, in childhood. The capacity to adhere to urinary tract epithelial cells characterizes E. coli strains that cause acute pyelonephritis. Adherence of uropathogenic E. coli is the result of a specific interaction between bacterial adhesins and glycolipid receptors on the host cells, especially the globoseries of glycolipids which share the Galactose alpha 1-greater than 4Galactose beta disaccharide (Gal alpha 1-greater than 4Gal beta). In childhood UTI, Gal alpha 1-greater than 4Gal beta-binding bacteria caused significantly higher body temperature, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and pyuria, and lower renal concentrating capacity, than E. coli lacking this specificity. The Gal alpha 1-greater than 4Gal beta-binding bacteria thus appeared to be more potent inducers of inflammation than other strains. Since inflammation may lead to tissue damage we examined the relationship of infection with Gal alpha 1-greater than 4Gal beta-positive bacteria to renal scarring. The frequency of renal scarring was 5% in boys with Gal alpha 1-greater than 4Gal beta-positive and 40% in boys with Gal alpha 1-greater than 4Gal beta-negative E. coli. Bacterial binding to Gal alpha 1-greater than 4Gal beta can be detected with a commercially available test reagent. This reagent can thus be used as an effective predictor of risk for renal scarring. Interleukin-6 (IL-6) is a pyrogen and inducer of the acute phase reactants. It was shown to be produced locally in the urinary tract, in response to UTI, and to spread systemically. Mucosal challenge with dead bacteria was sufficient to induce the IL-6 response. Circulating IL-6, and/or IL-1 and tumor necrosis factor could explain the fever, as well as increased ESR and CRP found in association with acute symptomatic UTI.

Isolation and comparison of Escherichia coli strains from canine and human patients with urinary tract infections

We analyzed Escherichia coli strains isolated from dogs with urinary tract infections (UTIs) in an attempt to determine if any of these strains were similar to E. coli isolated from humans with UTIs. Using genotypic and phenotypic traits, we identified four canine and six human E. coli UTI isolates that all appeared to be closely related or identical. All isolates shared similar DNA sequences for pyelonephritis-associated pili (pap), alpha-hemolysin (hly), and insertion sequence 5 (IS5), on the basis of Southern blot analysis. Similar outer membrane protein, pilin, and plasmid profiles were obtained for each of the isolates, although minor heterogeneity was observed. All of these isolates expressed a neuraminidase-sensitive binding phenotype in contrast to the majority of human isolates, which are known to express an adhesin that recognizes terminal digalactoside residues. Taken together, these results suggest that similar E. coli uropathogens may be capable of infecting both dogs and humans. To determine if the intestinal tracts of dogs were a reservoir for uropathogenic E. coli, eight paired rectal and urine pap+ E. coli strains were cultured from dogs with UTIs. By using the same genotypic and phenotypic criteria described above as a basis for strain identity, seven of eight urine-rectal pairs showed intrapair identity. However, each urine-rectal pair displayed a unique overall profile and could be distinguished from the other pairs. We conclude that the uropathogen colonizing the bladders of dog can also be the predominant strain colonizing the intestinal tracts.

Virulence of Escherichia coli in relation to host factors in women with symptomatic urinary tract infection

The relationship between bacterial characteristics and the severity of urinary tract infection in adults has not been clarified. In this study, Escherichia coli strains (n = 178) were prospectively collected from women with community-acquired urinary tract infection. The isolates were identified by O:K:H serotype and characterized for adherence, hemolysin production, and serum bactericidal resistance. The patients had acute pyelonephritis with or without complicating factors and acute cystitis. Nine serotypes (O1:K1:H7, O1:K1:H-, O2:K1:H-, O4:K12:H1, O7:K1:H-, O9:K34:H-, O16:K1:H6, O16:K1:H-, and O75:K5:H-) comprised 65% of the strains in uncomplicated pyelonephritis, but were significantly less often encountered in complicated pyelonephritis or cystitis. Adherence was the single property most characteristic of the pyelonephritogenic clones. Adhesins specifically recognizing Gal alpha 1----4Gal beta-containing receptors occurred in 80% of strains in uncomplicated pyelonephritis, in 50% of strains in complicated infections, and in 37% of cystitis strains. Hemolysin production and serum resistance did not correlate with any disease pattern. Advanced age did not seem to reduce the selection of virulent E. coli to cause pyelonephritis. These results demonstrate in women a relationship between E. coli virulence and the severity of urinary tract infection analogous to that previously observed in pediatric populations and also illustrate the balance between host resistance and bacterial virulence in the urinary tract.

Faecal colonization with P-fimbriated Escherichia coli between 0 and 18 months of age

A prospective study of faecal colonization with P-fimbriated Escherichia coli between 0 and 18 months of age was conducted in 751 healthy infants. The influence of breast-feeding and treatment with antibiotics on this colonization was studied. Colonization with P-fimbriated E. coli increased with age from 10% at 6 days to 30% at 18 months of age (P less than 0.01). Breast-feeding influenced colonization at 6 weeks of age when breast-fed children harboured fewer bacterial species (P less than 0.001) and fewer P-fimbriated E. coli (P = 0.06) than bottle-fed infants. Treatment with antibiotics increased the colonization rate with P-fimbriated E. coli at the age of 11 months (P less than 0.05). However, this was not true for treatment with ampicillin, which increased colonization rate with Gram-negative species other than E. coli (P less than 0.05). Fifty per cent (378) of all children were colonized and a quarter (183) had pure cultures of P-fimbriated E. coli in at least one faecal sample. The clinical importance of this colonization remains to be shown.

P-fimbriated Escherichia coli in children with acute cystitis

P-fimbriation of Escherichia coli is an important factor in the pathogenesis of childhood pyelonephritis. The present study investigates children with single episodes of symptomatic non-febrile urinary tract infection, i.e. cystitis, with respect to clinical appearance and bacteriology, especially the frequency of P-fimbriated E. coli. The study included 75 children, 57 of whom had their first attack of urinary tract infection. E. coli was the causative agent in 88% (66/75) of the infections, and 48% (32/66) of E. coli strains were P-fimbriated. No association was found between identification of P-fimbriated E. coli at index infection and proneness to reinfection during the following six-month period. It is suggested that P-fimbriated E. coli is a virulence factor even in lower urinary tract infections, when occurring in single, symptomatic episodes.

Epidemiological aspects of P-fimbriated Escherichia coli. IV. Extraintestinal E. coli infections before the age of one year and their relation to fecal colonization with P-fimbriated E. coli

In two retrospective studies we have found outbreaks of E. coli pyelonephritis and septicemia to be due to nosocomial spread and fecal colonization with virulent E. coli strains in the neonatal ward of Danderyd Hospital. The incidence of extraintestinal E. coli infections before the age of one year was therefore prospectively studied in all children born at Danderyd Hospital during two and a half years (n = 7963). The number of infections was correlated to the previous fecal colonization with P-fimbriated E. coli. During this study we found no outbreaks of E. coli infections. The incidence of E. coli pyelonephritis before the age of one year was 0.6-0.7%, which we propose to be a baseline incidence. This corresponds well with the low incidence of fecal colonization with P-fimbriated E. coli found among these children. Fecal colonization with P-fimbriated E. coli during this non-epidemic period had no predictive value for the individual child for the later development of pyelonephritis.

Adherence of Escherichia coli and Proteus mirabilis to human transitional cells

This study utilizes a light microscopy assay for bacterial adherence to human male transitional cells. Prior light microscopy studies have used voided squamous cells, periurethral cells or scraped vaginal cells, which are less representative of the cells lining the majority of the urinary tract. Using a modification of previous bacterial adherence assays, the mean adherence for 28 strains of E. coli in 92 bacteria-cell incubations was 10.2 +/- 11.5 (standard deviation) bacteria per cell. The mean adherence for 20 strains of P. mirabilis in 60 bacteria cell incubations was 8.1 +/- 11.4. No statistically significant difference in adherence between E. coli and P. mirabilis was found (p greater than 0.05). Studies comparing the adherence of E. coli isolated from the urine of patients with pyelonephritis (eight strains), cystitis (10 strains) and anal swabs of females without urinary tract infections (10 strains), showed no statistically significant differences in mean adherence (p greater than 0.05). However, there was a trend toward higher adherence in the more virulent groups. Experiments comparing the adherence of P. mirabilis isolated from infected renal stones to P. mirabilis isolated from anal swabs of female patients without history of P. mirabilis UTI revealed no statistically significant differences in mean adherence between the two groups (p greater than 0.05). These data do not support previous contentions that P. mirabilis adhere poorly to human transitional cells. The absence of a significant difference in adherence among strains of E. coli and P. mirabilis that differ in clinical pathogenicity suggests that factors other than adherence contribute to their virulence.

Escherichia coli in extra-intestinal infections

When Theodor Escherich (1885a, b) first describedEscherichia colihe looked on it as a saprophytic organism. Soon several investigators found that colibacteria could be isolated from intestinal infections and from many infections outside the intestine, like urinary tract infections (UTI), cholecystitis, wound infections, meningitis, septicaemia, pulmonary infections, and many more. Uhlenhuth (1897) showed that coli strains from pathological processes were more pathogenic in animal experiments than strains isolated from the normal intestine. Smith (1927), who examined strains from white scours in calves, showed that spontaneous acapsular mutants could be obtained from certain colibacteria, and that such mutants were less virulent when injected intra-peritoneally into guinea-pigs.

AFA-I, a cloned afimbrial X-type adhesin from a human pyelonephritic Escherichia coli strain. Purification and chemical, functional and serologic characterization

AFA-I, a mannose-resistant, P-independent, X-binding afimbrial Escherichia coli adhesin was purified from a recombinant strain and chemically, functionally and serologically characterized. AFA-I exists on the bacterial surface and free as a macromolecular aggregate in the supernatant of spent culture medium. It is composed of a single, repeating 16-kDa polypeptide subunit. The AFA-I protein amino acid composition is remarkable for the presence of 22% non-polar hydrophobic residues and 2.5-3.0 cysteines per subunit. Since AFA-I travels as a monomer in sodium dodecyl sulfate/polyacrylamide gel electrophoresis under non-reducing conditions, no disulfide bonds exist between subunits and at least one free sulfhydryl per subunit is available. The AFA-I N-terminal amino acid sequence residues 1-24 was unrelated to E. coli fimbrial sequences; however, the N-terminus of AFA-I and GV-12, another E. coli afimbrial protein, was asparagine. HB101 (pIL 14), the AFA-I recombinant strain, agglutinated only human and gorilla erythrocytes, indicating a preference for receptor molecules on the red cells of man and the anthropoid apes. AFA-I did not bind glycophorin A or sialyl glycosides and is therefore distinct from the E. coli X-binding adhesins with M and S specificity. The AFA-I receptor was found to be abundant and diffusely distributed on HeLa tissue culture monolayer cell surfaces by indirect fluorescent microscopy. Anti-AFA-I sera bound AFA-I in Western blots of 4 out of 16 X-binding E. coli urine isolates. They did not bind MS or P pili. AFA-I may be exemplary of an adhesin class significant for the pathogenesis of human urinary tract infections.

Gal-Gal binding and hemolysin phenotypes and genotypes associated with uropathogenic Escherichia coli

To determine whether uropathogenic strains of Escherichia coli exhibit a distinctive constellation of phenotypes, we examined 44 urinary isolates from women with radiologically normal urinary tracts and pyelonephritis, cystitis, or asymptomatic bacteriuria and 73 fecal isolates from healthy control subjects. The strains were characterized by their O serogroup, by their binding specificity (as determined by adhesins), and by their production of hemolysin and colicin V. In addition, the strains were assessed for homologous gene sequences by means of DNA-hybridization probes prepared from cistrons that encode hemolysin and the Gal-Gal binding adhesin--two determinants of virulence, which cause tissue injury and promote bacterial colonization of uroepithelia, respectively. In contrast to most isolates from normal feces and from the urine of patients with asymptomatic bacteriuria, pyelonephritis strains belong to a small number of O serogroups; all express the Gal--Gal binding adhesin and 75 per cent are hemolytic. A gene probe for the Gal--Gal binding adhesin, derived from the chromosome of one strain from a patient with pyelonephritis, hybridized with the DNA of all other pyelonephritis strains. The probe for the hemolysin gene hybridized with DNA from all other hemolytic strains. These data indicate that most cases of pyelonephritis are due to a small number of pathogenic clones that express critical determinants of virulence, and that the nucleotide sequences for hemolysin and the Gal--Gal binding adhesin in heterologous strains share homology. We are tempted to speculate that the gene products of these shared regions of the genome might form the basis for a vaccine against pyelonephritis.

Pathogenic significance of P-fimbriated Escherichia coli in urinary tract infections

The over-all aim of this study was to determine the pathogenic significance, and bacteriological and serological characteristics of P-fimbriated organisms isolated from a general population of patients with bacteriuria. A P-receptor specific particle agglutination test was used to identify P-fimbriated bacteria among 2,010 isolates from male and female patients with bacteriuria (age range infancy to 91 years). Of the 2,010 isolates 206 (10.2 per cent) were positive for P-fimbriae by the P-receptor specific particle agglutination test. Only Escherichia coli was found to be P-fimbriated, with an incidence of 21.5 per cent among 956 Escherichia coli isolates. The critical characteristic of pyelonephritic strains of Escherichia coli was P-fimbriation. In cases of nonobstructive acute pyelonephritis 100 per cent of the infecting bacteria were P-fimbriated. The data indicated clearly that the serotype, biotype, presence of type 1 fimbriae (mannose sensitive), undefined mannose-resistant adhesions, hemolysin production and motility of P-fimbriated Escherichia coli were clinically unimportant differential strain characteristics and not indicative of the virulence of P-fimbriated Escherichia coli within clinical syndromes. Isogenic P-fimbriated Escherichia coli strains were isolated from noncompromised patients in all clinical categories, that is pyelonephritis, asymptomatic bacteriuria and cystitis. A variety of bacterial strains appears to be capable of causing acute pyelonephritis in the presence of obstructive uropathic conditions, regardless of P-fimbriation. Therefore, P-fimbriation becomes a noncritical factor in compromised patients. The P-receptor specific particle agglutination test is a simple and rapid method to determine whether bacteria are P-fimbriated and may be an important screening method to identify those bacteria isolated from individuals at risk for nonobstructive acute pyelonephritis.

Gal-Gal pyelonephritis Escherichia coli pili linear immunogenic and antigenic epitopes

The linear immunogenic and antigenic structure of E. coli Gal-Gal pili from the recombinant strain HU 849 was investigated with nine synthetic peptides corresponding to regions of the pilus sequence predicted to contain hydrophilic beta-turns. Five peptides, as bovine serum albumin conjugates, were found by anti-HU 849 pilus serum and were thus designated "immunogenic epitopes." Peptides corresponding to R 25-38, R 38-50, and R 48-61 (which jointly comprise the single intramolecular disulfide loop), and R 103-116, were bound in low titer. A prominent immunogenic epitope was specified by a peptide corresponding to R 65-75. Four peptides, as thyroglobulin conjugates, elicited antisera in rabbits that bound intact HU 849 pili. These were designated "antigenic epitopes." Two prominent antigenic epitopes were localized to peptides corresponding to R 5-12 and R 93-104, whereas peptides corresponding to R 65-75 and R 119-131 represented two minor antigenic epitopes. None of the peptide antisera bound Gal-Gal pili from heterologous strains except anti-R 93-104 and anti-R 5-12. In 8 of the 10 Gal-Gal-binding pyelonephritis isolates tested, anti-R 5-12 detected a protein with an apparent molecular weight of 18,000 co-migrating with several Gal-Gal pili. Anti-R 93-104 detected a corresponding protein in 4 of 8 fecal and 7 of 12 pyelonephritis Gal-Gal-binding isolates; however, it also bound apparently unrelated proteins of higher molecular weight.

Molecular basis of Escherichia coli colonization of the upper urinary tract in BALB/c mice. Gal-Gal pili immunization prevents Escherichia coli pyelonephritis in the BALB/c mouse model of human pyelonephritis

Most human pyelonephritis Escherichia coli isolates express both mannose (MS)- and globoside (Gal-Gal)-binding pili. An ascending E. coli urinary tract infection model was established in the 16-wk-old female BALB/c mouse to compare the pathogenic significance of MS and Gal-Gal pili and their efficacy as vaccines for the prevention of pyelonephritis. The distribution and density of pilus receptor compounds in urogenital tissues and as soluble compounds in urine were determined with antibodies to the synthetic receptor analogues, alpha D-Gal(1----4) beta D-Gal and alpha D-Man(1----2) alpha D-Man. Both carbohydrates were detected in vagina, bladder, ureter, and renal pelvis epithelium and in collecting duct and tubular cells. A pilus receptor compound also was detected in urine. It competitively inhibited the binding capacity of MS pili and was found to be physically, chemically, and immunologically related to Tamm-Horsfall uromucoid. Infectivity and invasiveness were quantitatively and histologically characterized for four E. coli strains: J96, a human pyelonephritis strain that expresses both MS and Gal-Gal pili; two recombinant strains prepared from J96 chromosomal DNA encoding MS pili or Gal-Gal pili; and the nonpiliated K12 recipient. Intravesicular administration of J96 (10(6) colony-forming units [CFU]) resulted in renal colonization and invasion in each of nine mice. The Gal-Gal clone (10(6) CFU) colonized the kidneys in each of 10 mice but did not invade. In contrast, the MS clone (10(6) CFU) did not colonize renal epithelium or invade. This effect was superceded when larger doses (greater than or equal to 10(10) CFU) of the MS clone were administered in volumes that cause acute vesicoureteric reflux. The efficacy was determined of vaccines composed of pure MS or Gal-Gal pili or the lipopolysaccharide containing O somatic antigen of the challenge strain, J96. The Gal-Gal pilus vaccine blocked renal colonization in 19 of 22 mice and renal invasion in 10 of 11 mice. Gal-Gal pili may be useful immunogens for the prevention of pyelonephritis in anatomically normal urinary tracts.

Gene clusters governing the production of hemolysin and mannose-resistant hemagglutination are closely linked in Escherichia coli serotype O4 and O6 isolates from urinary tract infections

The genes encoding alpha-hemolysin and mannose-resistant hemagglutination were shown to be closely linked in cloned DNA from two Escherichia coli urinary tract isolates of serotypes O4 (J96) and O6 (C1212). DNA hybridization experiments demonstrated that the hly and mrh gene clusters of other E. coli O6 serotypes were also linked. Colony hybridizations showed that most normal fecal E. coli do not contain hly and mrh DNA but much of the intervening DNA between these two gene clusters is common among all E. coli. We have further demonstrated that there is a small (about 1 kilobase) region of homology located on both sides of the hly sequence and present elsewhere in the C1212 strain. We suggest that linkage of hly and mrh occurred through a transposition event, and we discuss the potential significance of this linkage in the acquisition of virulence determinants by these bacteria.

Hemolysin production as a virulence marker in symptomatic and asymptomatic urinary tract infections caused by Escherichia coli

Potential virulence, as defined by combined levels of adhesion to urinary epithelial cells, serum resistance, and mouse toxicity, was assessed for Escherichia coli strains causing symptomatic and asymptomatic urinary tract infections in relation to the carriage of hemolysin and other suspected virulence determinants. Hemolysin production (Hly), associated with certain O (O4, O6, O18, and O75), K (5), and hemagglutination (VI and VII) antigenic types but not colicin V production (Cva), was evident in 83 and 60% of isolates in groups possessing high potential virulence and in only 11 and 6% of those with low virulence. Strains of particular O-types were not more virulent per se, but among the serotypes, specific combinations of virulence factors appeared decisive, e.g., O18 HAVI B/D/G Hly(+) K5(+/-) and O18 HAIII/IVB/V Hly(-) Cva(+/-) K1(+/-) strains were, respectively, of high and low potential virulence. Isolates with high potential virulence were found to a similar extent in symptomatic and asymptomatic infections.

Variable adherence of uropathogenic Escherichia coli to epithelial cells from women with recurrent urinary tract infection

The adherence of 74 Escherichia coli strains to vaginal and buccal epithelial cells from women with recurrent urinary tract infections was studied. The strains were isolated from the urine, vaginal introitus or anal mucosa of women with recurrent bacteriuria. Vaginal and anal isolates were judged to be associated with urinary tract infection if they had the same biotype and serotype as the strain isolated subsequently from the urine. Adherence levels of urinary and anal isolates, and vaginal isolates associated with urinary tract infection were similar for vaginal and buccal cells. Adherence of vaginal isolates not associated with urinary tract infection was significantly lower than adherence of urinary isolates for vaginal (p less than 0.001) and buccal (p less than 0.005) epithelial cells. A positive nonlinear correlation between vaginal and buccal adherence was observed for urinary (r equals 0.87, p less than 0.0001), vaginal (r equals 0.70, p less than 0.0005) and anal (r equals 0.32, p equals 0.047) isolates. Strains of O-serogroups commonly and less commonly associated with bacteriuria had similar adherence. The results suggest that adherence of vaginal isolates is associated with the ability to cause urinary tract infections. The strong correlation between vaginal and buccal cell receptivity suggests that susceptibility to such infections may be controlled by genotypic traits.

Frequency and clinical features of urinary tract infection in paediatric out-patients in Nigeria

A survey of urinary tract infections (UTI) was conducted in a paediatric out-patient department in Northern Nigeria over six months. The most common presenting complaints of UTI were pyrexia of unknown origin (PUO) and mild diarrhoea. The frequency of symptomatic UTI in out-patients was estimated at 0.4%. Asymptomatic UTI was common in children with nephrotic syndrome (16%) and severe malnutrition (23%). Abnormalities of the urinary tract were found on I.V.P. in four out of twelve boys and one out of nine girls with symptomatic infection. Micturating cystograms (MCUG) were of less value because even if severe ureteric reflux was found, long term follow-up was not practical. Follow-up could be maintained with greater success from local clinics.

Antigenic heterogeneity of haemagglutination type VI fimbriae produced by Escherichia coli isolated from patients with bacteremia

In previous work it was observed that the majority of Escherichia coli strains isolated from the blood of bacteremia patients possess fimbriae which mediate mannose-resistant hemagglutination (HA) of human and monkey erythrocytes; this HA pattern (HA type VI) is different from those of enterotoxigenic E. coli possessing the colonization factor antigen CFA/I or CFA/II, which are also mannose-resistant HA positive. We and other investigators have found that HA type VI fimbriae may function as colonization factor antigens, especially in urinary tract infections. The work reported here was concerned with determining the number of antigenic types of fimbriae responsible for the HA type VI property. Fimbriae were isolated by hydrophobic interaction chromatography from four isolates of E. coli possessing the same HA pattern but belonging to different serotypes; antifimbrial antiserum was prepared by hyperimmunization of rabbits. Homologous and heterologous antifimbrial antibody titers were determined by the indirect enzyme-linked immunosorbent assay, bacterial agglutination by the tube method, and the HA inhibition test. Antiserum against the fimbriae of strain LY-71 (O4:H1) produced a high homologous titer but low or insignificant titers with fimbriae of strains LY-63 (O6:H31), LY-154 (O25:H(-)) and LY-156 (O2:H(-)). Antiserum against the fimbriae of strain LY-63 produced high titers with its own and with LY-71 fimbriae but insignificant titers with the fimbriae of strains LY-154 and LY-156. LY-154 and LY-156 fimbriae were highly cross-identical but antigenically different from those of LY-63 and LY-71. Twenty-five other test strains all identified with at least one of the prototype strains, as determined by HA inhibition tests performed with the four antifimbrial sera, although these belonged to a wide variety of serotypes. These data indicate the existence of at least two major different antigenic types of HA type VI fimbriae and possibly three, depending on the nature of the unidirectional crossidentity observed between the fimbriae of strains LY-63 and LY-71.

Occurrence of P-fimbriated Escherichia coli in urinary tract infections

The occurrence of Escherichia coli possessing P blood-group-specific adhesins (P-fimbriae) was examined in 97 children with urinary tract infections and 82 healthy controls. P-fimbriae were present in 91% (33/35) of the urinary strains causing acute pyelonephritis. Among strains causing cystitis and asymptomatic bacteriuria P-fimbriae were found in 19% and 14% of cases, respectively. Only 7% of faecal isolates from healthy controls carried P-fimbriae. The results were similar in three different studies. In most of the children with acute pyelonephritis the urinary pathogen was the predominant E. coli strain of the periurethral and faecal flora.

Hemolysin and K antigens in relation to serotype and hemagglutination type of Escherichia coli isolated from extraintestinal infections

Escherichia coli isolated from cases of bacteremia and from a variety of urinary tract infections were characterized according to serotype (O:H antigenicity), K type (possession of K1, K2, K3, K12, or K13), hemagglutination (HA) type, and production of beta-hemolysin. Results obtained with the bacteremia and urinary tract infection isolates were similar except for more hemolytic isolated from urine than from blood (42 versus 29%) and more K1+ isolates from blood than from urine (50 versus 29%). A close correlation was found between Ha type VI (production of fimbriae which mediate mannose-resistant HA of human and African green monkey erythrocytes) and the production of hemolysin or K1 capsular antigen or both. Most (95 of 98, or 95%) of the HA type VI+ blood isolates and most (146 of 164, or 89%) of the HA type VI+ urine isolates produced hemolysin or K1 or both, in contrast to 22 and 26%, respectively, of those belonging to HA types other than HA type VI. Also, 76% of all hemolytic and 70% of all K1+ isolates belonged to HA type VI. Remarkably few of the HA type VI+ isolates (13%) and even fewer of the HA type VI- isolates (3%) produced both K1 and hemolysin; these belonged mainly to serotypes O16:H6, O18:H7 and O2:H4. Other major serogroups were usually K1+/hemolysin- (O1, O7) or K1-/hemolysin+ (O2, O4, O6). At least 74% (262 of 351) and possibly as many as 83% (293 of 351) of those isolates which produced mannose-resistant HA of human erythrocytes were classified as HA type VI+; 31 isolates produced mannose-resistant HA with all erythrocytes tested. Taking serogroup and serotype into consideration, we conclude that the E. coli fimbrial hemagglutinin(s) responsible for the HA type VI phenotype will prove to be the same as the virulence-associated mannose-resistant adhesins of uropathogenic E. coli which other investigators have characterized as unique fimbrial antigens detectable by mannose-resistant HA of human erythrocytes.

Characterisation of Neisseria gonorrhoeae from women with simultaneous infections at two sites

Infection with two strains of Neisseria gonorrhoeae was found in paired cultures from 8.7% (6/69) of women who had infections of the cervix, rectum, or urethra. Paired gonococcal cultures from each patient were characterised by auxotyping, susceptibility to four antibiotics, and acrylamide gel electrophoresis patterns of the gonococcal cell proteins.

Attachment of Escherichia coli to urinary sediment epithelial cells from urinary tract infection-prone and healthy children

Escherichia coli isolated from patients with recurrent urinary tract infections were tested for ability to attach to human urinary sediment epithelial cells in vitro. Higher mean capacity to bind bacteria was found for epithelial cells of the patient from whom the E. coli strain had been isolated than for epithelial cells from subjects without a history of urinary tract infection. The two populations were age matched. No relation was found between the age of the cell donor (0 to 15 years) and the capacity for E. coli attachement.

Adhesiveness to urinary tract epithelial cells of fecal and urinary Escherichia coli isolates from patients with symptomatic urinary tract infections or asymptomatic bacteriuria of varying duration

Adhesiveness to human urinary tract epithelial cells was high for Escherichia coli strains isolated from patients with acute pyelonephritis and acute cystitis, and low for asymptomatic bacteriuria strains detected at screening. Escherichia coli bacteria causing asymptomatic reinfections, detected near the onset of bacteriuria, adhered more than those detected at screening. No difference in the adhesive ability was found between fecal isolates of the strain causing urinary tract infection, isolated at or before onset of bacteriuria, and the urinary strain in symptomatic or asymptomatic patients. Normal fecal Escherichia coli from non-bacteriuric patients adhered less than all other strains tested.

Relationship of hemagglutination to other biological properties of serologically classified isolates of Escherichia coli

The ability of 170 serologically classified strains of Escherichia coli to agglutinate human erythrocytes was examined. Erythrocytes of blood group A were more sensitive indicators of this property than were those of groups B or O. The predominant receptor was shown to be mannose containing; however, an additional receptor was found in two of nine strains studied. Natural mannose-like inhibitors were not found in unconcentrated urine obtained from 12 humans. Isolates from the urine or blood of patients with infections agglutinated erythrocytes significantly more frequently than did isolates from feces. Urine isolates of 10 common serogroups and isolates of less common serogroups did not differ in their ability to agglutinate erythrocytes. Among isolates from the urine of patients with infections, the ability to agglutinate erythrocytes did not correlate with either the serogroup of the strain or the clinical syndrome of the patient. Of the several other biological properties that were examined, only the production of colicins showed a significant association with the ability to agglutinate human erythrocytes.

[Typing of Escherichia coli O and K antigens in patients with urinary tract infections (author's transl)]

In a long-term investigation in children and adult patients with urinary tract infection, 1403 Escherichia coli strains were serotyped and 266 strains were subjected to serological investigation. The most frequently occurring O groups were O6, O8, O2, O18, O4, O75, O1, O22, O7 and O9. L type antigens were predominant among the K antigens. Infants in whom pyelonephritis manifested itself for the first time exhibited an above average rate of infection with O2, O4 and O75. A reinfection rate of 84 to 91% was observed in children in follow-up investigations.