Mannose-sensitive Agglutination Research Articles

In vitro efficacy of phytotherapeutics suggested for prevention and therapy of urinary tract infections.

To analyse the therapeutic efficacy of various phytotherapeutics and their antimicrobial compounds with regard to strain specificity and dose dependence. A representative strain collection of 40 uropathogenic bacteria isolated from complicated and uncomplicated urinary tract infection was subjected to various virulence assays (bacterial growth, mannose-sensitive agglutination, and motility) to determine the therapeutic impact of various compounds with antimicrobial activity. We tested proanthocyanidins (PAC), D-mannose, rosemary extract (Canephron®), and isothiocyanates (Angocin®). D-mannose efficiently blocked the adhesive properties of all type 1 fimbriae-positive isolates in low concentration (0.2%), but showed no bacteriostatic effect. PAC also actively blocked agglutination, but the concentration varied considerably among isolates. Escherichia coli required the highest concentration (10%), while Enterobacter cloacae responded to low concentrations (0.1%). Allyl isothiocyanates not only impaired agglutination in all tested isolates, but also had a dramatic impact on flagella-mediated motility in Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis (p < 0.001). The administration of rosemary extracts revealed a strong bacteriostatic effect in growth assays. All tested strains were strongly inhibited by the addition of 10μg/ml or 1μg/ml of purified rosemary extractions with the exception of Serratia marcescens. Morganella morganii responded only to 10μg/ml. Phytotherapeutics and small-molecular compounds like mannosides have the potential to become an integral part in a multi-modal treatment concept for the treatment and prevention of urinary tract infections. Their efficiency can be optimised when strain specificities and therapeutic concentrations are taken into account.

A Constitutively Mannose-Sensitive AgglutinatingSalmonella entericasubsp.entericaSerovar Typhimurium Strain, Carrying a Transposon in the Fimbrial Usher GenestbC, Exhibits Multidrug Resistance and Flagellated Phenotypes

Static broth culture favors Salmonella enterica subsp. enterica serovar Typhimurium to produce type 1 fimbriae, while solid agar inhibits its expression. A transposon inserted in stbC, which would encode an usher for Stb fimbriae of a non-flagellar Salmonella enterica subsp. enterica serovar Typhimurium LB5010 strain, conferred it to agglutinate yeast cells on both cultures. RT-PCR revealed that the expression of the fimbrial subunit gene fimA, and fimZ, a regulatory gene of fimA, were both increased in the stbC mutant when grown on LB agar; fimW, a repressor gene of fimA, exhibited lower expression. Flagella were observed in the stbC mutant and this phenotype was correlated with the motile phenotype. Microarray data and RT-PCR indicated that the expression of three genes, motA, motB, and cheM, was enhanced in the stbC mutant. The stbC mutant was resistant to several antibiotics, consistent with the finding that expression of yhcQ and ramA was enhanced. A complementation test revealed that transforming a recombinant plasmid possessing the stbC restored the mannose-sensitive agglutination phenotype to the stbC mutant much as that in the parental Salmonella enterica subsp. enterica serovar Typhimurium LB5010 strain, indicating the possibility of an interplay of different fimbrial systems in coordinating their expression.

Klebsiella pneumoniae type 3 fimbriae agglutinate yeast in a mannose-resistant manner

The ability of bacterial pathogens to express different fimbrial adhesins plays a significant role in virulence. Thus, specific detection of fimbrial expression is an important task in virulence characterization and epidemiological studies. Most clinical Klebsiella pneumoniae isolates express type 1 and type 3 fimbriae, which are characterized by mediation of mannose-sensitive agglutination of yeast cells and agglutination of tannic acid-treated ox red blood cells (RBCs), respectively. It has been observed that K. pneumoniae isolates agglutinate yeast cells and commercially available sheep RBCs in a mannose-resistant manner. Thus, this study was initiated to identify the adhesin involved. Screening of a mutant library surprisingly revealed that the mannose-resistant agglutination of yeast and sheep RBCs was mediated by type 3 fimbriae. Specific detection of type 1 fimbriae expression in K. pneumoniae was feasible only by the use of guinea pig RBCs. This was further verified by the use of isogenic fimbriae mutants and by cloning and expressing K. pneumoniae fimbrial gene clusters in Escherichia coli. Yeast agglutination assays are commonly used to detect type 1 fimbriae expression but should not be used for bacterial species able to express type 3 fimbriae. For these species, the use of guinea pig blood for specific type 1 fimbriae detection is essential. The use of commercially available sheep RBCs or yeast is an easy alternative to traditional methods to detect type 3 fimbriae expression. Easy and specific detection of expression of type 1 and type 3 fimbriae is essential in the continuous characterization of these important adhesive virulence factors present in members of the Enterobacteriaceae.

Detection of Extraintestinal Pathogenic Escherichia coli among Normal Stool Flora of Young, Healthy, Unmarried Males &amp; Females as Predisposing Factor to Extraintestinal Infections:A Comparison Study

In this study we surveyed the dominant normal stool flora of randomly selected healthy, young (18-23 years old), unmarried (doctrinal) Iraqi college students (males and females) for the carriage of extraintestinal pathogenic E. coli (ExPEC). ExPEC virulence was detected phenotypically by mannose resistant hemagglutination of human red blood cells (MRHA) and mannose sensitive (MS) agglutination of Bakers' yeast (Saccharomyces cerevisceae). From 88 college students, 264 E. coli isolates were obtained (3 isolates per person): 123 from 41 females and 141 from 47 males. Of these isolates, 56% (149/264) caused MS agglutination of yeast cells and 4.16% (11/264) showed MRHA. Eighty two percent (9/11) of the isolates with MRHA also caused MS agglutination of yeast cells. Statistically the difference is not significant (P &lt; 0.05) among males and females regarding the MS agglutination of yeast cells: 59% (72/123) of females' isolates vs. 55% (77/141) of males' isolates. Conversely, the difference is clear regarding the carriage of isolates with MRHA. All the isolates with MRHA were distributed among females' dominant stool flora (11/123: 8.94%) whereas none of the males' dominant stool flora showed MRHA (0/141: 0%). Five females out of 41 (12.19%) had isolates with MRHA. All the three isolates in 2 of these 5 females showed MRHA, 2 isolates in another 2 showed MRHA, and only one isolate in 1 female caused MRHA. Therefore we can say that the difference among males and females in fecal carriage of E. coli ,with characteristics of ExPEC, can be a predisposing factor of females to ExPEC infections more than males.

PapMutant of Avian Pathogenic Escherichia coli O1, an O1:K1:H7 Strain, Is AttenuatedIn Vivo

P or Pap fimbriae of avian pathogenic Escherichia coli (APEC) have previously been shown to be important in the pathogenesis of colibacillosis. However, no study has been done to ascertain the effects of deletion of the genes responsible for P fimbrial biogenesis on APEC's in vitro and/or in vivo characteristics. In the present study, all 11 genes of the pap gene cluster were deleted from APEC O1, the recently sequenced APEC strain, and the wild-type strain was compared to the mutant (ECPAP1) for changes in certain phenotypic characteristics and virulence for chickens. Both APEC O1 and ECPAP1 demonstrated mannose-sensitive agglutination of guinea pig and chicken erythrocytes, but only APEC O1 demonstrated mannose-resistant hemagglutination and P-receptor binding properties. The in vivo experiments revealed that ECPAP1 was markedly attenuated as compared to its wild-type strain APEC O1. These findings suggest that P fimbriae are involved in the virulence of APEC O1.

Mannanoligosaccharide agglutination by Salmonella enterica strains isolated from carrier pigs

Type-1 fimbriae are associated with most Salmonella enterica serovars and are an essential factor for host colonization. Mannanoligosaccharides (MOS), a prebiotic that is agglutinated by type-1 fimbriae, are proposed for the control of enterobacteria colonization and may be an alternative to Salmonella control in pigs. The aim of this study was to evaluate the capability of porcine Salmonella strains to adhere to MOS in vitro. A total of 108 strains of Salmonella sp. isolated from carrier pigs were evaluated for the amplification of fimA and fimH genes, agglutination of MOS and hemagglutination. In all tested strains, amplicons of expected size were detected for both fimA and fimH gene. In the hemagglutination assays, 31 (28.7%) strains presented mannose–sensitive agglutination of erythrocytes, indicating that the strains were expressing type-1 fimbriae. Considering only strains expressing the type-1 fimbriae, 23 (74.2%) presented a strong agglutination of MOS, 3 (9.6%) a weak reaction and 5 (16.2%) none. The results indicate that Salmonella enterica strains expressing type-1 fimbriae can agglutinate effectively in vitro to MOS.

Expression of P, S, and F1C adhesins by cytotoxic necrotizing factor 1-producing Escherichia coli from septicemic and diarrheic pigs.

Nineteen papC-positive cytotoxic necrotizing factor 1 (CNF1)-producing Escherichia coli isolates from pigs with septicemia or diarrhea were tested for the presence of pap-, sfa-, and afa-related sequences encoding P/Prs, S/F1C, and Dr/AFA adhesins respectively. Production of adhesins by isolates was tested by mannose-resistant hemagglutination (MRHA), sialidase treatment of erythrocytes and particle agglutination tests. Production of P, S, and F1C fimbriae by isolates was also examined by immunofluorescence. All isolates were pap+ by PCR. Eighteen isolates (95%) were MRHA for ovine and human A erythrocytes and exhibited GalNac-GalNac receptor specificity associated with class III P(Prs) adhesins. Fifteen (79%) of the 19 isolates reacted with antisera specific for one or more different P fimbrial serotypes on immunofluorescence. Three of these isolates also demonstrated Gal-Gal receptor specificity associated with class I or II P fimbrial adhesins. Fifteen (79%) of the isolates were sfa+ by PCR. Seven of these isolates exhibited sialidase-sensitive MRHA of bovine and human O erythrocytes and reacted with serum specific for S fimbriae on immunofluorescence. Seven of the 8 sfa+ isolates which were MRHA-negative for bovine erythrocytes reacted with serum specific for F1C fimbriae on immunofluorescence. All isolates produced type 1 fimbriae as determined by mannose-sensitive agglutination of yeast cells. None of the isolates were afa+ by PCR or colony hybridization. Results suggest that most pap+ porcine CNF1-producing E. coli isolates express P fimbriae bearing class III (Prs) type adhesins. In addition, most of these isolates also produce S or F1C fimbriae.

Regulation of type 1 fimbriae synthesis and biofilm formation by the transcriptional regulator LrhA of Escherichia coli

Type 1 fimbriae of Escherichia coli facilitate attachment to the host mucosa and promote biofilm formation on abiotic surfaces. The transcriptional regulator LrhA, which is known as a repressor of flagellar, motility and chemotaxis genes, regulates biofilm formation and expression of type 1 fimbriae. Whole-genome expression profiling revealed that inactivation of lrhA results in an increased expression of structural components of type 1 fimbriae. In vitro, LrhA bound to the promoter regions of the two fim recombinases (FimB and FimE) that catalyse the inversion of the fimA promoter, and to the invertible element itself. Translational lacZ fusions with these genes and quantification of fimE transcript levels by real-time PCR showed that LrhA influences type 1 fimbrial phase variation, primarily via activation of FimE, which is required for the ON-to-OFF transition of the fim switch. Enhanced type 1 fimbrial expression as a result of lrhA disruption was confirmed by mannose-sensitive agglutination of yeast cells. Biofilm formation was stimulated by lrhA inactivation and completely suppressed upon LrhA overproduction. The effects of LrhA on biofilm formation were exerted via the changed levels of surface molecules, most probably both flagella and type 1 fimbriae. Together, the data show a role for LrhA as a repressor of type 1 fimbrial expression, and thus as a regulator of the initial stages of biofilm development and, presumably, bacterial adherence to epithelial host cells also.

Analysis of Escherichia coli strains causing bacteriuria during pregnancy: selection for strains that do not express type 1 fimbriae.

Escherichia coli isolates from patients with bacteriuria of pregnancy were compared by PCR with isolates from patients with community-acquired cystitis for the presence of established virulence determinants. The strains from patients with bacteriuria of pregnancy were less likely to carry genes for P-family, S-family, and F1C adhesins, cytotoxic necrotizing factor 1, and aerobactin, but virtually all of the strains carried the genes for type 1 fimbriae. Standard mannose-sensitive agglutination of yeast cells showed that only 15 of 42 bacteriuria strains (36%) expressed type 1 fimbriae compared with 32 of 42 strains from community-acquired symptomatic infections (76%) (P < 0.01). This difference was confirmed by analysis of all isolates for an allele of the type 1 fimbrial regulatory region (fim switch), which negates type 1 fimbrial expression by preventing the fim switch from being inverted to the on phase. This allele, fimS49, was found in 8 of 47 bacteriuria strains from pregnant women (17.0%) compared with 2 of 60 strains isolated from patients with cystitis (3.3%) (P < 0.05). Determination of the phase switch orientation in vivo by analysis of freshly collected infected urine from patients with bacteriuria showed that the fim switch was detectable in the off orientation in 17 of 23 urine samples analyzed (74%). These data indicate that type 1 fimbriae are not necessary to maintain the majority of E. coli bacteriurias in pregnant women since there appears to be selection against their expression in this particular group. This is in contrast to the considered role of this adhesin in community-acquired symptomatic infections. The lack of type 1 fimbria expression is likely to contribute to the asymptomatic nature of bacteriuria in pregnant women, although approximately one-third of the bacteriuria isolates do possess key virulence determinants. If left untreated, this subset of isolates pose the greatest threat to the health of the mother and unborn child.

Production and characterization of a monoclonal antibody against mannose-sensitive hemagglutinin of Vibrio cholerae.

We have generated murine monoclonal antibodies (MAb) against Vibrio cholerae mannose-sensitive hemagglutinin (MSHA) using conventional hybridoma procedures. Seven hybridomas were obtained and one characterized. Hybridoma 2F12/F1 secreted an antibody of the IgG3 type that reacted with a 17-kDa antigen corresponding to the product of the mshA gene. This MAb inhibited mannose-sensitive agglutination of chicken erythrocytes by EL tor and O139 vibrios. Vibrios expressing MSHA activity inhibited binding of the antibody secreted by 2F12/F1 to MSHA-coated microtiter plates.

Expression of P, S, and F1C adhesins by cytotoxic necrotizing factor 1-producing Escherichia coli from septicemic and diarrheic pigs

Nineteen papC-positive cytotoxic necrotizing factor 1 (CNF1)-producing Escherichia coli isolates from pigs with septicemia or diarrhea were tested for the presence of pap-, sfa-, and afa-related sequences encoding P/Prs, S/F1C, and Dr/AFA adhesins respectively. Production of adhesins by isolates was tested by mannose-resistant hemagglutination (MRHA), sialidase treatment of erythrocytes and particle agglutination tests. Production of P, S, and F1C fimbriae by isolates was also examined by immunofluorescence. All isolates were pap + by PCR. Eighteen isolates (95%) were MRHA for ovine and human A erythrocytes and exhibited GalNac-GalNac receptor specificity associated with class III P(Prs) adhesins. Fifteen (79%) of the 19 isolates reacted with antisera specific for one or more different P fimbrial serotypes on immunofluorescence. Three of these isolates also demonstrated Gal-Gal receptor specificity associated with class I or II P fimbrial adhesins. Fifteen (79%) of the isolates were sfa + by PCR. Seven of these isolates exhibited sialidase-sensitive MRHA of bovine and human O erythrocytes and reacted with serum specific for S fimbriae on immunofluorescence. Seven of the 8 sfa + isolates which were MRHA-negative for bovine erythrocytes reacted with serum specific for F1C fimbriae on immunofluorescence. All isolates produced type 1 fimbriae as determined by mannose-sensitive agglutination of yeast cells. None of the isolates were afa + by PCR or colony hybridization. Results suggest that most pap + porcine CNF1-producing E. coli isolates express P fimbriae bearing class III (Prs) type adhesins. In addition, most of these isolates also produce S or F1C fimbriae.

Influence of the spermicidal compound nonoxynol-9 on the adhesion of E. coli to human epithelial cells

Two type I piliated strains of Escherichia coli were cultured in medium supplemented with physiologically used concentrations of the spermicidal compound nonoxynol-9. Their ability to adhere to HeLa cells in tissue culture was found to increase significantly (p<0.05). For strain 12313, there was a 2.3- and 1.9-fold increase when cultured in 5% and 12.5% (w/v) nonoxynol-9 respectively, and adhesion of strain 12269 increased by 1.7 times after growth in 12.5% (w/v) nonoxynol-9. The increased adhesion was accompanied by loss of mannose-sensitive yeast agglutination and hemagglutination. The absence of type I piliation was confirmed by electron miscroscopy and was accompanied by a decrease in cell surface hydrophobicity. The ability of E. coli to grow in high concentrations of nonoxynol-9, combined with increased adhesion to human epithelial cells in vitro, may contribute to the increased incidence of E. coli urinary tract infection seen in women using diaphragms and spermicidal preparations for contraception.

Identification of a mannose-binding pilus on Vibrio cholerae El Tor

The mannose-sensitive hemagglutinin (MSHA) that is associated with Vibrio cholerae strains of El Tor biotype is identified as a pilus composed of subunits with a molecular mass of approximately 17 kDa. In immunoelectron microscopy, a monoclonal antibody against MSHA that inhibited El Tor vibrio-mediated mannose-sensitive agglutination of chicken erythrocytes or El Tor bacterial binding to mannose-coated agarose beads, bound specifically to repetitive subunits along typical fimbriae extending from the surface of El Tor vibrios. No such pili were seen on the surface of MSHA negative classical vibrios, although non-surface exposed fimbrial subunits could be demonstrated in these bacteria by immunoblotting techniques.

Binding of bacteria to carbohydrates immobilized on beads to demonstrate the presence of cell‐associated hemagglutinins in Vibrio cholerae

We describe a phase contrast microscopy method for direct observation of classical and El Tor vibrios to agarose beads containing covalently attached L-fucose or D-mannose. Binding of the vibrios to L-fucose beads was found to correlate with fucose-sensitive agglutination of human O erythrocytes, while binding of bacteria to beads with D-mannose was consistent with mannose-sensitive agglutination of chicken erythrocytes. Furthermore, vibrios expressing both fucose and mannose-sensitive hemagglutinins adhered equally to L-fucose and D-mannose-containing beads. Because this procedure is neither subject to biological variations in different populations of erythrocytes nor affected by other factors known to interfere with hemagglutination tests, it offers a suitable, more robust and specific alternative to detect functional adhesins in Vibrio cholerae and other bacteria.

Recognitory bacterial surface lectins which mediate its mannose-specific adherence to eukaryotic cells.

Cell surface protein were found to play a role in the sugar-specific molecular mechanism by which bacteria adhere to mammalian cells. We have demonstrated that at least three different types of lectin-like proteins mediate the mannose-sensitive adherence of gram negative bacteria to epithelial cells. One group of such lectins was shown in our study to be associated with the bacterial flagellum. Flagella isolated from Escherichia coli 7343 and Serratia marcescens 8347 exhibited mannose-sensitive agglutination of yeast cells; however, the flagella of the two bacteria differ in the molecular structure of their protein subunits. Another class of lectins comprises the bacterial fimbriae (also known as type 1 pili), which were previously shown to facilitate the mannose-sensitive adherence of various bacteria to mammalian cells. Fimbriae isolated from E. coli 346 were reversibly dissociated by saturated guanidine hydrochloride to their protein subunits. The dissociated subunits retained in part their mannose-binding ability, and were reassembled into fimbriae-like structures by removal of the denaturant under specific conditions. Mannose-sensitive yeast agglutinating activity of E. coli 2699, as well as of its isolated outer membranes devoid of fimbriae or flagella, was abolished by pretreatment with trypsin. It is therefore believed that the mannose-sensitive adherence of these bacteria is mediated also by lectin-like proteins associated directly with the outer membrane.

Participation of pili and cell wall adhesion in the yeast agglutination activity of Escherichia coli.

Escherichia coli strain 2699 (O6:K13) which had been isolated from a case of urinary tract infection exhibited pili during the stationary phase (24 to 40 h), but not during the exponential phase (4 h), when grown in static broth culture. The bacteria were also piliated when grown for 24 h on agar. They agglutinated Saccharomyces cerevisiae (baker's yeast) in the piliated as well as in the nonpiliated state. The agglutinations were mannose sensitive, i.e., they could be inhibited with 50 mM methyl-alpha-mannoside. The bacteria were first depiliated by shearing and then used for the isolation of outer membrane vesicles with an Omnimixer. Purified pili and outer membranes were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electron microscopy. The pili could be demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis only after treatment at low pH or in saturated guanidine hydrochloride which is typical of the common type 1 pili. Depiliated bacteria, purified pili, and purified outer membranes gave mannose-sensitive agglutination of S. cerevisiae. The findings are discussed with respect to possible mechanisms of cell agglutination.

Modified method for studying bacterial adhesion to isolated uroepithelial cells and uromucoid

Several problems have been encountered with the application of published methods for the study of bacterial adherence to isolated uroepithelial cells. Of particular importance is the observation that urinary mucus traps some organisms but not others. Established techniques have been modified to overcome these difficulties and so allow a distinction to be made between adherence of bacteria to uromucoid and adherence to uroepithelial cells per se. The modified method was used to assess the ability of 34 urinary isolates of Escherichia coli to adhere to uroepithelial cells, uromucoid, or both after serial subculture in nutrient broth. The ability of the organisms to produce mannose-sensitive (MS) agglutination of guinea pig erythrocytes and mannose-resistant (MR) agglutination of human erythrocytes was tested simultaneously and taken to indicate possession of MS type 1 fimbriae andated MR fimbriae, respectively. Results revealed that only MS-positive organisms adhered to uromucoid (P less than 0.001), whereas MR-positive strains showed significantly greater attachment to uroepithelial cells than did MR-negative strains (P less than 0.05). These observations demand that published data derived from the use of a methodology in which no differentiation can be made between adherence to uromucoid and adherence to cells should be interpreted with caution.

Binding specificity of piliated strains of Escherichia coli and Salmonella typhimurium to epithelial cells, saccharomyces cerevisiae cells, and erythrocytes.

The binding to mammalian cells of piliated enteric bacteria and the inhibition of the binding by antibodies to purified pili were studied. The target cells were epithelial cells from human bucca and human and rat urinary tracts, erythrocytes from various species, and Saccharomyces cerevisiae cells. The strains were selected to represent the two main agglutination patterns of enteric bacteria: mannose-resistant agglutination of human and other erythrocytes and mannose-sensitive agglutination of guinea pig and other erythrocytes. Escherichia coli 3669 caused only mannose-resistant agglutination, E. coli 6013 caused only mannose-sensitive agglutination, and E. coli 3048 caused both types of agglutination simultaneously. Salmonella typhimurium SH6749 exhibited only mannose-sensitive hemagglutination and was included to allow comparison of its pili with those of E. coli strains. The range of epithelial cells to which the bacteria adhered was related to their agglutination patterns. All four strains attached to human buccal cells. Only E. coli strains 3669 and 3048, which caused mannose-resistant agglutination, adhered to human urinary tract epithelial cells, and only those strains that caused mannose-sensitive agglutination adhered to rat urinary tract epithelial cells. The binding of S. typhimurium SH6749, but not of the other strains with mannose-sensitive agglutination, was significantly inhibited by d-mannose. Globotetraosylceramide, a glycolipid present in the human urinary tract epithelium, inhibited attachment to human uroepithelial cells of the two strains with mannose-resistant hemagglutination. As tested by the enzyme-linked immunosorbent assay, cross-reactions between type 1 pili of the E. coli strains were strong, but those between S. typhimurium and E. coli mannose-sensitive pili were weak. The two pili that induced mannose-resistant hemagglutination on E. coli did not cross-react. Significant inhibition of adhesion of all four strains was obtained with the homologous anti-pilus antiserum. The binding of bacteria to mammalian cells may thus be mediated by several types of bacterial pili reacting with different receptors on mammalian cells.

Adhesion, hemagglutination, and virulence of Escherichia coli causing urinary tract infections.

The capacity of 453 Escherichia coli strains to agglutinate erythrocytes and yeast cells and to attach to human urinary tract epithelial cells was tested. The strains were isolated from the urine of patients with acute pyelonephritis, acute cystitis, or asymptomatic bacteriuria and from the stools of healthy school children. Three main patterns of hemagglutination were found: (i) mannose-resistant agglutination of human erythrocytes alone or simultaneously with mannose-sensitive agglutination of guinea pig erythrocytes; (ii) only mannose-sensitive agglutination of guinea pig and other erythrocytes; and (iii) no agglutination. Strains with mannose-resistant agglutination of human erythrocytes alone or in combination with mannose-sensitive hemagglutination attached in high numbers to human urinary tract epithelial cells. Bacteria inducing only mannose-sensitive hemagglutination attached in low numbers, and non-agglutinating strains did not bind to the urinary tract epithelial cells. The bacterial surface antigen(s) mediating mannose-resistant hemagglutination of human erythrocytes and attachment to human urinary tract epithelial cells may be one factor selecting for E. coli from among the fecal flora which infect the urinary tract. The highest proportion of strains with this property was found among acute pyelonephritis isolates (77%), and the lowest proportion of strains with this property was found among normal fecal E. coli (16%).

Adhesion of fimbriate Escherichia coli to bovine mammary-gland epithelial cells in vitro (Plates VII)

The adhesion of bovine and a human isolate of Escherichia coli to epithelial cells from the teat and lactiferous sinuses of the udder was examined. Adhesion was detected with bacterial suspensions that produced mannose-sensitive agglutination of guinea-pig red cells. Adhesion to epithelial cells could be inhibited by mannose and the degree of adhesion occurring with a suspension correlated with its haemagglutinating activity. This demonstrated that fimbriae were responsible for the adhesion. The observation that whole milk inhibited attachment of E. coli to cells in vitro indicates that such attachment may not occur in vivo in the lactating cow.