Mannose-resistant Hemagglutination Research Articles

A Hemagglutination, serum resistance, cell surface hydrophobicity and ESBL production among uropathogenic Escherichia coli

Abstract
 Background
 Bacteria have adapted themselves with increased pathogenesis and drug resistance mechanisms to overcome host defense systems. Uropathogenic E. coli (UPEC) responsible for symptomatic Urinary tract infections (UTIs) carry diverse virulence factors and extended spectrum beta-lactamase (ESBL) production which play pivotal role in pathogenesis and antibiotic resistance. Objective: The purpose of this study was to determine the phenotypic expression of virulence factors; i.e. Hemagglutination, serum resistance, cell surface hydrophobicity and resistance factor ESBL production among UPEC isolates. Methods: In this prospective study 50 drug resistant UPEC strains were evaluated for hemagglutination by slide method, cell surface hydrophobicity by salt aggregation test, serum resistance by serum bactericidal assay and ESBL detection by double disc synergy test. Results: Among 50 UPEC strains 46 (92%) showed mannose resistant hemagglutination, 48 (96%) were found to be serum resistant, 40 (80%) isolates were positive for cell surface hydrophobicity, while 43 (86%) were ESBL producers. Most of the UPEC that expressed virulence factors were ESBL producers as well. Conclusion: Over all, this study indicated that MDR UPEC isolates have expressed a number of virulence factors with ESBL production, which explains how pathogens have increased their virulence and resistance repertoire resulting in treatment failures.

The Immunogenicity and Properties of a Whole-Cell ETEC Vaccine Inactivated with Psoralen and UVA Light in Comparison to Formalin.

Inactivated whole-cell vaccines present a full repertoire of antigens to the immune system. Formalin treatment, a standard method for microbial inactivation, can modify or destroy protein antigenic epitopes. We tested the hypothesis that photochemical inactivation with psoralen and UVA light (PUVA), which targets nucleic acid, would improve the immunogenicity of an Enterotoxigenic E. coli (ETEC) vaccine relative to a formalin-inactivated counterpart. Exposure of ETEC H10407 to PUVA using the psoralen drug 4'-Aminomethyltrioxsalen hydrochloride (AMT) yielded replication-incompetent bacteria that retained their metabolic activity. CFA/I-mediated mannose-resistant hemagglutination (MRHA) was equivalent for PUVA-inactivated and live ETEC, but was severely reduced for formalin-ETEC, indicating that PUVA preserved fimbrial protein functional integrity. The immunogenicity of PUVA-ETEC and formalin-ETEC was compared in mice ± double mutant heat-labile enterotoxin (dmLT) adjuvant. Two weeks after an intramuscular prime/boost, serum anti-ETEC IgG titers were similar for the two vaccines and were increased by dmLT. However, the IgG responses raised against several conserved ETEC proteins were greater after vaccination with PUVA-ETEC. In addition, PUVA-ETEC generated IgG specific for heat-labile toxin (LT) in the absence of dmLT, which was not a property of formalin-ETEC. These data are consistent with PUVA preserving ETEC protein antigens in their native-like form and justify the further testing of PUVA as a vaccine platform for ETEC using murine challenge models.

Type1 and 3 fimbriae phenotype and genotype as suitable markers for uropathogenic bacterial pathogenesis via attachment, cell surface hydrophobicity, and biofilm formation in catheter-associated urinary tract infections (CAUTIs).

Objective(s):Catheters are one of the factors for complicated urinary tract infections. Uropathogenic bacteria can attach to the catheter via cell surface hydrophobicity (CSH), form biofilms, and remain in urinary tract. The study was evaluated phenotypic and genotypic characteristics of fimbriae in Klebsiella pneumoniae and uropathogenic Escherichia coli (UPEC) isolates from patients with catheter-associated urinary tract infections (CAUTIs) and their association with biofilm formation. Materials and Methods:Urine specimens were collected through catheters in patients with CAUTIs. Sixty bacterial isolates were identified by biochemical tests. For determination of biofilm formation a tissue culture plate was used. Microbial adhesion to hydrocarbons (MATH) was conducted for CSH determination. The mannose-sensitive haemagglutination (MSHA) and mannose-resistant haemagglutination (MRHA) were determined for type 1 and type 3 fimbriae. Finally, the presence of genes encoding fimbriae was determined by PCR.Results:All isolates showed strong CSH, biofilm capacity and MRHA phenotype. The results showed that 20% of UPEC and 23% of K. pneumoniae isolates contained MSHA phenotypes. There was a significant association between biofilm formation and MSHA phenotype in UPEC isolates. The frequency of fimA (80%) and fimH (96.6%) in K. pneumoniae isolates was higher than UPEC isolates. Both types of bacterial isolates with MSHA phenotypes harbored the fimH gene. Conclusion:The phenotypic and genotypic characteristics of two bacterial species were highly similar. Also, the type of fimbriae affected bacterial biofilm formation through catheterization. It seems that fimH and mrk gene cluster subunits are suitable markers for identifying bacterial pathogenesis.

A Randomized, Double-Blind, Placebo-Controlled Pilot Study to Assess the Urinary Anti-Adhesion Activity Following Consumption of Cranberry + health™ Cranberry Supplement (P06-114-19)

ObjectivesUrinary tract infections (UTIs) are the second most common bacterial infections and are often treated with antibiotics. The North American cranberry is recommended for UTI prophylaxis in women with recurrent UTI as a nutritional alternative approach. The ability of cranberry components or their metabolites to inhibit the adhesion of uropathogenic E.coli to the bladder is considered as an important mechanism by which cranberry mitigates UTIs. The objective of this study was to evaluate the anti-adhesion activity of urine from healthy individuals against both type I pili and P-fimbriae uropathogenic E.coli, after the consumption of Cranberry + health™ Cranberry Supplement. MethodsIn this randomized, double-blind, placebo-controlled pilot trial (n = 20), subjects consumed two cranberry chews, one in the morning and one in the evening. Clean-catch urine samples collected at baseline and post-intervention (0–3 h, 3–6 h, 6–9 h, 9–12 h, 12–24 h, 24–30 h, 30–36 h) were tested for anti-adhesion activity utilizing both a mannose-resistant human red blood cell hemagglutination assay specific for P-fimbriae E. coli and a T24 cell line model for type I pili E.coli (UTI89). ResultsUrinary ex vivo anti-adhesion activity against P-fimbriae E. coli after consuming cranberry chew was significantly greater (p < 0.05) than placebo chew at 0–3 h, 3–6 h, 6–9 h, 9–12, and 12–24 time point. Urinary anti-adhesion activity against type I pili E.coli (UTI89) following cranberry chew was significantly greater (p < 0.1) than placebo chew at 3–6 h, 6–9 h, and 12–24 h time point. ConclusionsAcute consumption of Cranberry + health™ Cranberry Supplement provides ex vivo anti-adhesion activity, which may help to improve urinary tract health. Funding SourcesOcean Spray Cranberries, Inc.

Outcome of acute urinary tract infections caused by uropathogenic Escherichia coli with phenotypically demonstrable virulence factors.

Background:Urinary tract infection (UTI) caused by uropathogenic Escherichia coli (UPEC) strains is one of the most important community-acquired infections in the world. The presence of virulence factors is closely related with the pathogenesis of UTI.Methods:The present study was conducted on 150 isolates of UPEC obtained from symptomatic and asymptomatic cases of UTIs with significant counts (≥105 CFU/ml) during 1 year. UPEC isolates were studied for hemolysis on 5% sheep blood agar, mannose-sensitive hemagglutination (MSHA), mannose-resistant hemagglutination (MRHA), and biofilm formation by recommended methods. Patients with UTI due to UPEC showing virulence factors were evaluated for the treatment received and the outcome of treatment. These were compared with the outcomes of patients whose culture samples grew UPEC without demonstrable virulence factors.Results:The study showed hemolysin production in 40% of the isolates. Forty percent of the isolates showed the presence of P fimbriae (MRHA) and 60% showed Type 1 fimbriae (MSHA). Biofilm formation capacity of all UPEC isolates was classified into three categories, strong biofilm producers (4%), moderate biofilm producers (88%), and nonbiofilm producers (8%). Patients harboring all three virulence factors showed 76% recovery compared to patients harboring strains with no demonstrable virulence factors, who showed 100% recovery.Conclusion:The present study has shown the production of various virulent factors and developing drug resistance in UPEC. Treatment outcomes of patients harboring strains with no virulence factors seem to be better than the ones which contain multiple virulence factors. UPEC occurs because of multiple virulence factors. Biofilm formation and MRHA are more likely to be seen in catheterized patients. The drug resistance among UPEC is on rise; therefore, the selection of appropriate antibiotics (after antibiotic susceptibility testing) is must for proper treatment of patients and to avoid emergence of drug resistance. Significant number of the UPEC isolates was sensitive to nitrofurantoin, and half of the isolates were sensitive to cotrimoxazole, so treatment is by giving these drugs orally.

A randomized, double-blind, placebo-controlled pilot study to assess bacterial anti-adhesive activity in human urine following consumption of a cranberry supplement.

Urinary tract infections (UTIs) are one of the common bacterial infections treated with antibiotics. The North American cranberry is recommended for prophylaxis in women with recurrent UTIs as a nutritional alternative. The ability of cranberry components and their metabolites to inhibit adhesion of uropathogenic Escherichia coli (E. coli) is an important mechanism by which cranberry mitigates UTIs. The objective of this study was to evaluate urinary anti-adhesion activity against type 1 and P-type uropathogenic E. coli after consumption of cranberry +health™ cranberry supplement (cranberry chew). In this randomized, double-blind, placebo-controlled, crossover design pilot trial (n = 20), subjects consumed two cranberry or placebo chews, one in the morning and one in the evening. Clean-catch urine samples collected at the baseline and post-intervention (0-3, 3-6, 6-9, 9-12, 12-24, 24-30, 30-36 h) were tested for anti-adhesion effects with a mannose-resistant human red blood cell hemagglutination assay specific for P-type E. coli, or a T24 cell line model for type 1 E. coli. Urinary anti-adhesion activity against P-type E. coli after consumption of the cranberry chew was significantly greater (p < 0.05) than that observed with placebo chew at all time points except 24-36 h. Ex vivo anti-adhesion effects on type 1 E. coli were greater (p < 0.05) after cranberry chew consumption than placebo chew at 3-6 and 6-9 h urine collections. In conclusion, consumption of cranberry +health™ cranberry supplement exhibited greater ex vivo urinary anti-adhesion activity compared to placebo, suggesting that it may have the potential to help promote urinary tract health.

Determination of phenotypic expression of the fimbriae and hemolysin of uropathogenic &amp;lt;i&amp;gt;Escherichia coli&amp;lt;/i&amp;gt; (UPEC)

Background: The bacterial strains that cause symptomatic urinary tract infections possess diverse distinctive properties that enable them to overcome the local host defences. In Escherichia coli , virulence results from the cumulative impact of several virulence factors, which can vary according to the patient populations. The study was undertaken to assess the prevalence of the virulence factors by phenotypic assays in the E. coli isolates which were isolated from patients with UTI from a tertiary care hospital in Kerala. Methods: A total of 300 E. coli isolates were obtained from symptomatic cases of urinary tract infections and 30 E. coli faecal isolates were obtained from apparently healthy individuals and they were tested for phenotypic properties like haemolysin production, mannose resistant hemagglutination to indicate P fimbriae, cell surface hydrophobicity. Results: Among the 300 E. coli isolates from the cases group, 135 (43.5%) were hemolytic, 106 (35.5%) were MRHA positive, 123 (41%) were hydrophobic. Among the 30 controls, 2 (6%) were hemolytic, 02 (6%) were MRHA positive and 04 (10%) were hydrophobic. The difference between the cases and the control group was significant (P &lt;0.001). Multiple virulence factors were observed in 51% of the isolates. Conclusion: The present study showed varied phenotypic expression of the virulence factors in the urinary isolates as compared to the fecal isolates.

Incidence of fimbriated strains amongst haemolytic Escherichia coli

A total of 23,007 clinical samples, 2,001 were identified as Escherichia coli (E.coli). Among these, 205 strains were haemolytic. One hundred eighty one E.coli were found haemolytic among urinary isolates. Two tests i.e. salt aggregation test (SAT) and haemagglutination test (HAT) with human type A erythrocytes were performed to know the incidence of fimbriated strains amongst haemolytic E.coli isolates. Mannose resistant haemagglutination and Mannose sensitive haemagglutination was observed in 95 (46.34%) and 15 (7.31%) strains respectively. Whereas cell surface hydrophobicity was shown by 139 (67.80%) strains. Seventy nine (38.53%) strains were both SAT and HAT positive. Twenty nine (14.14%) strains were both SAT and HAT negative i.e. non-fimbriated strains. Among urinary isolates, 21.8% were found to possess both haemolytic and haemagglutinating activity. Haemolytic activity of E.coli was found associated with fimbriated strains. Thus, both act as virulence factors for the pathogenesis of Urinary Tract Infection.

English

The present study was conducted in the Department of Microbiology, Konaseema Institute of Medical Sciences, Amalapuram, East Godavari District from August 2011 to January 2012. Fifty Escherichia coli (E.coli) strains isolated from urine samples of different clinical entities and 25 feacal isolates were studied for the detection of virulence markers of E.coli. There are 27 uropathogenic E.coli (UPEC) isolates from 50 E.coli & 5 UPEC from 25 controls. Among isolates tested the most common virulent marker is haemolysin 21 (42%), followed by Mannose resistant haemagglutination 16 (32%), cell surface hydrophobicity 13 (26%). In this, there are 14 cases with only one virulence marker, 8 with 2 marker combinations and 15 cases with combination of 3 markers.

Phenotypic Study of Virulence Factors in Escherichia Coli Isolated From Antenatal Cases, Catheterized Patients, and Faecal Flora

The bacterial strains that cause symptomatic urinary tract infections possess diverse distinctive properties that enable them to overcome the local host defenses. In Escherichia coli, virulence results from the cumulative impact of several virulence factors, which can vary according to the patient populations. Hence, a study was undertaken to assess the prevalence of the virulence factors in the E.coli isolates which were isolated from pregnant woman, catheterized patients and from the stool samples of healthy individuals. A total of 93 E.coli isolates were obtained from symptomatic cases of urinary tract infections and 31 E.coli faecal isolates were obtained from apparently healthy individuals and they were tested for haemolysin production, mannose resistant haemagglutination to indicate P fimbriae, cell surface hydrophobicity, and the gelatinase enzyme. Among the 93 E.coli isolates from the cases group, 39(41.9%) were haemolytic, 38(40.9%) were MRHA positive, 29(31.2%) were hydrophobic and 18(19.4%) were positive for gelatinase. Among the 31 controls, 01(3.2%) were haemolytic, 02(6.5%) were MRHA positive and 03(9.7%) were hydrophobic and none of the isolates were positive for gelatinase. The difference between the cases and the control group was significant (P<0.001).Multiple virulence factors were observed in 10% of the isolates. The present study showed that the expression of the virulence factors was more in the urinary isolates of the antenatal cases and in the catheterized patients as compared to the faecal isolates.

Oral Consumption of Cranberry Juice Cocktail Inhibits Molecular-Scale Adhesion of Clinical UropathogenicEscherichia coli

Cranberry juice cocktail (CJC) has been shown to inhibit the formation of biofilm by uropathogenic Escherichia coli. In order to investigate whether the anti-adhesive components could reach the urinary tract after oral consumption of CJC, a volunteer was given 16 oz of either water or CJC. Urine samples were collected at 0, 2, 4, 6, and 8 hours after consumption of a single dose. The ability of compounds in the urine to influence bacterial adhesion was tested for six clinical uropathogenic E. coli strains, including four P-fimbriated strains (B37, CFT073, BF1023, and J96) and two strains not expressing P-fimbriae but exhibiting mannose-resistant hemagglutination (B73 and B78). A non-fimbriated strain, HB101, was used as a control. Atomic force microscopy (AFM) was used to measure the adhesion force between a silicon nitride probe and bacteria treated with urine samples. Within 2 hours after CJC consumption, bacteria of the clinical strains treated with the corresponding urine sample demonstrated lower adhesion forces than those treated with urine collected before CJC consumption. The adhesion forces continued decreasing with time after CJC consumption over the 8-hour measurement period. The adhesion forces of bacteria after exposure to urine collected following water consumption did not change. HB101 showed low adhesion forces following both water and CJC consumption, and these did not change over time. The AFM adhesion force measurements were consistent with the results of a hemagglutination assay, confirming that oral consumption of CJC could act against adhesion of uropathogenic E. coli.

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.

Escherichia coli Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Properties

Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with Escherichia coli being responsible for >80% of all cases. Asymptomatic bacteriuria (ABU) occurs when bacteria colonize the urinary tract without causing clinical symptoms and can affect both catheterized patients (catheter-associated ABU [CA-ABU]) and noncatheterized patients. Here, we compared the virulence properties of a collection of ABU and CA-ABU nosocomial E. coli isolates in terms of antibiotic resistance, phylogenetic grouping, specific UTI-associated virulence genes, hemagglutination characteristics, and biofilm formation. CA-ABU isolates were similar to ABU isolates with regard to the majority of these characteristics; exceptions were that CA-ABU isolates had a higher prevalence of the polysaccharide capsule marker genes kpsMT II and kpsMT K1, while more ABU strains were capable of mannose-resistant hemagglutination. To examine biofilm growth in detail, we performed a global gene expression analysis with two CA-ABU strains that formed a strong biofilm and that possessed a limited adhesin repertoire. The gene expression profile of the CA-ABU strains during biofilm growth showed considerable overlap with that previously described for the prototype ABU E. coli strain, 83972. This is the first global gene expression analysis of E. coli CA-ABU strains. Overall, our data suggest that nosocomial ABU and CA-ABU E. coli isolates possess similar virulence profiles.

Dosage effect on uropathogenic Escherichia coli anti-adhesion activity in urine following consumption of cranberry powder standardized for proanthocyanidin content: a multicentric randomized double blind study

BackgroundIngestion of cranberry (Vaccinium macrocarpon Ait.) has traditionally been utilized for prevention of urinary tract infections. The proanthocyanidins (PACs) in cranberry, in particular the A-type linkages have been implicated as important inhibitors of primarily P-fimbriated E. coli adhesion to uroepithelial cells. Additional experiments were required to investigate the persistence in urine samples over a broader time period, to determine the most effective dose per day and to determine if the urinary anti-adhesion effect following cranberry is detected within volunteers of different origins.MethodsTwo separate bioassays (a mannose-resistant hemagglutination assay and an original new human T24 epithelial cell-line assay) have assessed the ex-vivo urinary bacterial anti-adhesion activity on urines samples collected from 32 volunteers from Japan, Hungary, Spain and France in a randomized, double-blind versus placebo study. An in vivo Caenorhabditis elegans model was used to evaluate the influence of cranberry regimen on the virulence of E. coli strain.ResultsThe results indicated a significant bacterial anti-adhesion activity in urine samples collected from volunteers that consumed cranberry powder compared to placebo (p < 0.001). This inhibition was clearly dose-dependent, prolonged (until 24 h with 72 mg of PAC) and increasing with the amount of PAC equivalents consumed in each cranberry powder regimen. An in vivo Caenorhabditis elegans model showed that cranberry acted against bacterial virulence: E. coli strain presented a reduced ability to kill worms after a growth in urines samples of patients who took cranberry capsules. This effect is particularly important with the regimen of 72 mg of PAC.ConclusionsAdministration of PAC-standardized cranberry powder at dosages containing 72 mg of PAC per day may offer some protection against bacterial adhesion and virulence in the urinary tract. This effect may offer a nyctohemeral protection.

Urinary Tract Infections in Renal Transplant Recipients: Virulence Traits of Uropathogenic Escherichia coli

Background Urinary tract infection (UTI) is the most common infectious complication after renal transplantation. Most infections are caused by uropathogenic Escherichia coli (UPEC). There are limited data on the prevalence of virulence traits among UPEC isolated from renal transplant recipients. This study compared the phenotypic and genotypic profiles of UPEC strains isolated from recipients with those from control patients. Methods E coli isolates that caused UTI in recipients versus nonimmunosuppressed control patients were characterized according to phylogenetic group and the presence of urovirulence genes pap1/pap2; sfa1/sfa2; afa1/afa2; aer1/aer2; and cnf1/cnf2. Results Thirty-six UPEC isolates from recipients and another 27 from control individuals were included in the study. The proportion of episodes of pyelonephritis in recipients (50%) versus control subjects (41%) was similar ( P = .46). However, secondary bacteremia was observed only among recipients ( n = 8; P < .001). There was no significant difference in the distribution of phylogenetic groups or the prevalence of analyzed virulence traits between UPEC isolated from the 2 groups. Nevertheless, strains associated with secondary bacteremia in recipients showed a higher prevalence of mannose-resistant hemagglutination ( P = .013). Conclusion The phenotypic and genotypic characteristics of UPEC isolated from recipients were similar to those from control patients at a tertiary care center. Secondary bacteremia in recipients was associated with a higher prevalence of mannose-resistant hemagglutination.

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.

Extended-Spectrum β-Lactamase Production Is Associated with an Increase in Cell Invasion and Expression of Fimbrial Adhesins in Klebsiella pneumoniae

Extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae strains are suggested to possess higher pathogenic potential than non-ESBL producers. Microbial adherence to and invasion of host cells are critical steps in the infection process, so we examined the expression of type 1 and 3 fimbrial adhesins by 58 ESBL-producing and 152 nonproducing isolates of K. pneumoniae and their abilities to invade ileocecal and bladder epithelial cells. Mannose-sensitive hemagglutination of guinea pig erythrocytes and mannose-resistant hemagglutination of ox erythrocytes were evaluated to determine the strains' abilities to express type 1 and type 3 fimbriae, respectively. Bacterial adhesion to and invasion of epithelial cells were tested by enzyme-linked immunosorbent assay and imipenem killing assay, respectively. The adherence of ESBL- and non-ESBL-producing strains to epithelial cells did not differ significantly (P > 0.05). In contrast, the proportion of strains capable of invading (>5% relative invasion) ileocecal and bladder epithelial cells was significantly higher among ESBL producers (81%, n = 47/58, and 27.6%, n = 16/58, respectively) than among non-ESBL producers (61%, n = 93/152, and 10%, n = 15/152, respectively) (P = 0.0084, odds ratio [OR] = 2.711, 95% confidence interval [CI] = 1.302 to 5.643 and P = 0.0021, OR = 4.79, 95% CI = 1.587 to 7.627). The mean invasion by ESBL producers (5.5% +/- 2.8% and 3.3% +/- 2.7%, respectively) was significantly higher than that by non-ESBL producers (2.9% +/- 2.6% and 1.8% +/- 2%, respectively) (P < 0.0001). Likewise, the proportion of ESBL producers coexpressing both fimbrial adhesins was significantly higher (79.3%; n = 46/58) than that of non-ESBL producers (61.8%; n = 94/152) (P = 0.0214; OR = 2,365; 95% CI = 1.157 to 4.834). Upon acquisition of SHV-12-encoding plasmids, two transconjugants switched on to produce type 3 fimbriae while expression of type 1 fimbriae was not affected. The acquisition of an ESBL plasmid appeared to upregulate the phenotypic expression of one or more genes, resulting in greater invasion ability.

Correlation between virulence factors and in vitro biofilm formation by Escherichia coli strains

The ability of 15 Escherichia coli strains to form biofilms on polystirene plates was studied. The strains were serotyped, and their phenotypic expression of surface virulence factors (VFs), and antibiotic susceptibility was also determined. Moreover, 30 VFs-associated genes were analysed, including 15 adhesins ( papC, papG and its three alleles, sfa/focDE, sfaS, focG, afa/draBC, iha, bmaE, gafD, nfaE, fimH, fimAvMT78, agn43, F9 fimbriae and type 3 fimbriae-encoding gene clusters), four toxins ( hlyA, cnf1, sat and tsh), four siderophore ( iron, fyuA, iutA and iucD), five proctetins/invasion-encoding genes ( kpsM II, kpsMT III, K1 kps variant- neuC, traT and ibeA), and the pathogenicity island malX and cvaC. Morphological appearance and thickness of biofilms of two strong and three weak biofilm producers were also studied by confocal laser scanning microscopy (CLSM). Seven strains were classified as strong biofilm producers and the remaining eight strains were regarded as weak biofilm producers. Mannose-resistant haemagglutination was the only phenotypically expressed surface virulence factor more frequently found in the strong biofilm group. Five virulence-associated genes were more common ( p < 0.05) in strong biofilm producers: papC and papG alleles, sfa/focDE, focG, hlyA and cnf1. CLSM images showed irregular biofilms with projections at the top mainly in strong biofilm.

Haemagglutination and siderophore production as the urovirulence markers of uropathogenic&lt;i&gt; &lt;i&gt;Escherichia&lt;/i&gt; coli&lt;/i&gt;

A total of 160 strains of Escherichia coli isolated from urine of patients with clinically diagnosed urinary tract infection were included in the study and 50 faecal isolates of E. coli were studied. They were studied for virulence factors, namely mannose-resistant and mannose-sensitive haemagglutination (MRHA, MSHA) and siderophore production. Among 160 urinary isolates of E. coli , 40 (25%) showed MRHA, siderophore production was seen in 156 (97.5%). In 50 faecal isolates, two (4%) were MRHA, four (8%) MSHA and siderophore production in two (4%). The results suggest that MRHA and siderophore production positive strains can be considered as UPEC.

HAEMAGGLUTINATION AND SIDEROPHORE PRODUCTION AS THE UROVIRULENCE MARKERS OF UROPATHOGENIC ESCHERICHIA COLI

A total of 160 strains of Escherichia coli isolated from urine of patients with clinically diagnosed urinary tract infection were included in the study and 50 faecal isolates of E. coli were studied. They were studied for virulence factors, namely mannose-resistant and mannose-sensitive haemagglutination (MRHA, MSHA) and siderophore production.Among 160 urinary isolates of E. coli, 40 (25%) showed MRHA, siderophore production was seen in 156 (97.5%). In 50 faecal isolates, two (4%) were MRHA, four (8%) MSHA and siderophore production in two (4%). The results suggest that MRHA and siderophore production positive strains can be considered as UPEC.