Impact of Rapid Molecular Multiplex Gastrointestinal Pathogen Testing in Management of Children during a Shigella Outbreak.

Fecal culture for isolation and identification of Shigella may take days. The BioFire FilmArray Gastrointestinal (GI) panel (bioMérieux, France) is a PCR-based assay that detects enteric pathogens including Shigella/enteroinvasive Escherichia coli (EIEC) in about an hour. The aim of this study was to evaluate the impact of GI panel detection of Shigella in a pediatric emergency department (ED) during an outbreak. Stool samples from children with acute gastroenteritis were tested by the GI panel. Test results were either withheld in preintervention (PRE) or reported to clinicians/families in the postintervention (POST) period. The impact of the GI panel testing on patient management and outcomes was measured. Shigella/EIEC was identified by the GI panel in the PRE (n = 30) and POST (n = 21) phase. The GI panel detected more Shigella infections than did culture; six of 31 (19.4%) Shigella GI panel-positive patients who also had stool cultures were missed by culture. Azithromycin therapy was prescribed for 20% of subjects in the PRE phase and 71.4% of subjects in the POST phase (P < 0.001). Time from the clinical encounter until starting azithromycin therapy was shorter in the POST phase (n = 9), 8.25 h (range, 6.37 to 52.37 h), than in the PRE phase (n = 1), 72 h. Six subjects in the PRE phase visited additional providers compared with one in the POST phase. Prompt diagnosis of shigellosis with the GI panel may provide the opportunity for prompt antimicrobial therapy and avoid additional visits to providers due to early definitive diagnosis. Prompt diagnosis of Shigella at an ED visit may optimize patient management and reduce transmission.

Maternal parechovirus A (PeV-A) shedding, serostatus, and the risk of central nervous system PeV-A infections in infants.

BACKGROUND: Parechovirus A (PeV-A) has emerged as a leading cause of infant central nervous system (CNS) infections. Risk factors associated with infant acquisition of PeV-A are not well understood. METHODS: We conducted prospective PeV-A/enterovirus (EV) CNS infection surveillance, enrolling 461 hospitalized infants <90 days old who underwent sepsis evaluations and lumbar puncture during 2011-2012. Infants were grouped by RT-PCR detection of PeV-A, EV, or neither virus (Neg) in CSF. We collected demographic/clinical data and tested specimens from all infants. For 427 mothers, we collected demographic/clinical data and evaluated PeV-A3 and EV shedding, and PeV-A3 neutralizing antibody for 147 mothers. RESULTS: PeV-A was detected in 40 infants (8.7%), 4 in 2011 and 36 in 2012. EV was detected in 35 infants (7.6%), 16 in 2011, and 19 in 2012. PeV-A infected infants presented with irritability, abdominal discomfort, fever, and tachycardia, plus both lymphopenia and absence of CSF pleocytosis which help differentiate PeV-A from EV CNS infection. PeV-A was detected in 9/427 maternal throat swabs; eight of their infants also had PeV-A CNS infection. Infants whose mothers had PeV-A3-positive throat swabs were more likely to be PeV-A3-positive than infants whose mothers had negative throat swabs (relative risk [RR], 13.4 [95% CI, 8.6 - 20.7]). Maternal PeV-A3 seropositivity decreased with increasing maternal age. Mothers of PeV-A-positive infants had lower median PeV-A3 neutralizing titers and were more likely seronegative. CONCLUSIONS: Maternal viral shedding, serostatus and neutralization titers appear to be important factors in infant PeV-A3 CNS infections.

Molecular Characterization of Mycoplasma pneumoniae Isolates in the United States from 2012 to 2018.

Mycoplasma pneumoniae is a major cause of community-acquired pneumonia. There are limited data in the United States on the molecular epidemiological characteristics of M. pneumoniae We collected 446 M. pneumoniae-positive specimens from 9 states between August 2012 and October 2018. Culture, antimicrobial susceptibility testing, P1 subtyping, and multilocus VNTR (variable-number tandem repeats) analysis (MLVA) were performed to characterize the isolates. Macrolide-resistant M. pneumoniae (MRMp) was detected in 37 (8.3%) specimens. P1 subtype 2 (P1-2) was the predominant P1 subtype (59.8%). P1 subtype distribution did not change significantly chronologically or geographically. The macrolide resistance rate in P1 subtype 1 (P1-1) samples was significantly higher than that in P1-2 (12.9% versus 5.5%). Six P1-2 variants were identified, including two novel types, and variant 2c was predominant (64.6%). P1-2 variants were distributed significantly differently among geographic regions. Classical P1-2 was more frequent in lower respiratory tract specimens and had longer p1 trinucleotide repeats. Classical P1-2 was most common in MRMp (35.7%), while variant 2c was most common in macrolide-susceptible M. pneumoniae (67.5%). Fifteen MLVA types were identified; 3-5-6-2 (41.7%), 4-5-7-2 (35.3%), and 3-6-6-2 (16.6%) were the major types, and four MLVA clusters were delineated. The distribution of MLVA types varied significantly over time and geographic location. The predominant MLVA type switched from 4-5-7-2 to 3-5-6-2 in 2015. MLVA type was associated with P1 subtypes and P1-2 variant types but not with macrolide resistance. To investigate the M. pneumoniae genotype shift and its impact on clinical presentations, additional surveillance programs targeting more diverse populations and prolonged sampling times are required.

Multicenter Clinical Evaluation of the Revogene Strep A Molecular Assay for Detection of Streptococcus pyogenes from Throat Swab Specimens.

Group A streptococcus (GAS) species cause bacterial pharyngitis in both adults and children. Early and accurate diagnosis of GAS is important for appropriate antibiotic therapy to prevent GAS sequalae. The Revogene Strep A molecular assay (Meridian Bioscience Canada Inc, Quebec City, QC, Canada) is an automated real-time PCR assay for GAS detection from throat swab specimens within approximately 70 min. This multicenter prospective study evaluated the performance of the Revogene Strep A molecular assay compared to that of bacterial culture. Dual throat swab specimens in either liquid Amies or Stuart medium were collected from eligible subjects (pediatric population and adults) enrolled across 7 sites (USA and Canada). Revogene Strep A and reference testing was performed within 7 days and 48 h of sample collection, respectively. Of the 604 evaluable specimens, GAS was detected in 154 (25.5%) samples by the reference method and in 175 (29%) samples by the Revogene Strep A assay. Revogene Strep A assay sensitivity and specificity were reported to be 98.1% (95% confidence interval [CI], 94.4 to 99.3) and 94.7% (95% CI, 92.2 to 96.4), respectively. The positive predictive value was 86.3% (95% CI, 80.4 to 90.6), negative predictive value was 99.3% (95% CI, 98.0 to 99.8) with a 1.0% invalid rate. Discrepant analysis with alternative PCR/bidirectional sequencing was performed for 24 false-positive (FP) and 3 false-negative (FN) specimens. Concordant results were reported for 17 (FP only) of 27 discordant specimens. The Revogene Strep A assay had high sensitivity and specificity for GAS detection and provides a faster alternative for GAS diagnosis.

Macrolide-Resistant Mycoplasma pneumoniae in the United States as Determined from a National Surveillance Program.

There are sparse data to indicate the extent that macrolide-resistant Mycoplasma pneumoniae (MRMp) occurs in the United States or its clinical significance. Between 2015 and 2018, hospitals in 8 states collected and stored respiratory specimens that tested positive for M. pneumoniae and sent them to the University of Alabama at Birmingham, where real-time PCR was performed for detection of 23S rRNA mutations known to confer macrolide resistance. MRMp was detected in 27 of 360 specimens (7.5%). MRMp prevalence was significantly higher in the South and East (18.3%) than in the West (2.1%). A2063G was the predominant 23S rRNA mutation detected. MICs for macrolide-susceptible M. pneumoniae (MSMp) were ≤0.008 µg/ml, whereas MICs for MRMp were 16 to 32 µg/ml. Patients with MRMp infection were more likely to have a history of immunodeficiency or malignancy. Otherwise, there were no other significant differences in the clinical features between patients infected with MRMp and those infected with MSMp, nor were there any differences in radiographic findings, hospitalization rates, viral coinfections, the mean duration of antimicrobial treatment, or clinical outcomes. There was no significant change in MRMp incidence over time or according to age, sex, race/ethnicity, or status as an inpatient or an outpatient. Patients with MRMp were more likely to have received a macrolide prior to presentation, and their treatment was more likely to have been changed to a fluoroquinolone after presentation. This is the first national surveillance program for M. pneumoniae in the United States. Additional surveillance is needed to assess the clinical significance of MRMp and to monitor changes in MRMp prevalence.

Emergence of Parechovirus A4 Central Nervous System Infections among Infants in Kansas City, Missouri, USA.

Among known parechovirus (PeV) types infecting humans, PeV-A3 (formerly HPeV3) and PeV-A1 (formerly HPeV1) are associated with pediatric central nervous system (CNS) infections. The prevalence of PeV-A3 among hospitalized infants with sepsis-like illness and viral CNS infection is well described; however, the contribution of PeV-A4 to infant CNS infection is relatively unexplored. We report the first 11 U.S. cases of PeV-A4 CNS infections occurring in Kansas City infants during 2010 to 2016 and compare the clinical presentation with that of PeV-A3. PeV-positive cerebrospinal fluid (CSF) specimens from 2010 to 2016 underwent sequencing for genotyping. Among all PeV-CSF positives, PeV-A4 was detected in 11 CSF samples from 2010 to 2016. PeV-A4 was first detected in 2010 (n = 1/4), followed by detections in 2014 (n = 1/39), 2015 (n = 6/9), and 2016 (n = 3/33). The median age of PeV-A4-infected infants in weeks (median, 4; range, 1 to 8) was similar to that of infants infected with PeV-A3 (median, 4; range, 0.25 to 8). Clinical characteristics of PeV-A4 (n = 11) were compared with those of select PeV-A3-infected children (n = 34) with CNS infections and found to be mostly similar, although maximum temperature was higher (P = 0.017) and fever duration was shorter (P = 0.03) for PeV-A4 than for PeV-A3. Laboratory test results were also similar between genotypes, although they showed significantly lower peripheral white blood cell (P = 0.014) and absolute lymphocyte (P = 0.04) counts for PeV-A4 infants. Like PeV-A3, PeV-A4 caused summer-fall seasonal clusters of CNS infections in infants, with mostly similar presentations. Further surveillance is necessary to confirm potential differences in laboratory findings and in fever intensity/duration.

Multicenter Clinical Evaluation of the Automated Aries Group A Strep PCR Assay from Throat Swabs.

Group A Streptococcus (GAS) is one of the leading causes of bacterial pharyngitis. Early GAS diagnosis is critical for appropriate antibiotic administration that reduces the risk of GAS sequelae and limits spread of the infection. The Aries Group A Strep (GAS) assay (Luminex, Austin, TX) is a fully automated PCR assay for direct detection of GAS in throat swab specimens in less than 2 h with minimum hands-on time. This multicenter prospective study evaluated the clinical performance of the Aries GAS assay compared to that of Streptococcus pyogenes culture. Subjects with symptoms consistent with pharyngitis were enrolled across four sites in the United States, and a throat swab in liquid Amies medium was obtained. Aries and reference testing was performed within 72 and 48 h after sample collection, respectively. Of 623 throat swab specimens from patients with pharyngitis (93.6% <18 years old, 54.3% female), the reference method yielded valid results for 618 specimens. Reference and Aries assay testing showed GAS-positive results for 160 (25.9%) and 166 (26.9%) specimens, respectively. Compared to the reference method, Aries assay sensitivity was 97.5% (95% confidence interval [CI], 93.7% to 99.0%), specificity was 97.8% (95% CI, 96.0 to 98.8%), positive predictive value was 94.0% (95% CI, 89.3% to 96.7%), and negative predictive value was 99.1% (95% CI, 97.7% to 99.7%). There were 10 false-positive and four false-negative detections with the Aries assay. Discrepant analysis with bidirectional sequencing yielded concordant results with the Aries assay for nine of 14 discordant samples. The Aries assay had high sensitivity and specificity for qualitative detection of group A Streptococcus from patients with pharyngitis.

Evaluation of RIDA®GENE norovirus GI/GII real time RT-PCR using stool specimens collected from children and adults with acute gastroenteritis.

BACKGROUND: Norovirus is the leading cause of epidemic and sporadic acute gastroenteritis (AGE) in the United States. Widespread prevalence necessitates implementation of accurate norovirus detection assays in clinical diagnostic laboratories. OBJECTIVE: To evaluate RIDA®GENE norovirus GI/GII real-time RT-PCR assay (RGN RT-PCR) using stool samples from patients with sporadic AGE. STUDY DESIGN: Patients between 14 days to 101 years of age with symptoms of AGE were enrolled prospectively at four sites across the United States during 2014-2015. Stool specimens were screened for the presence of norovirus RNA by the RGN RT-PCR assay. Results were compared with a reference method that included conventional RT-PCR and sequencing of a partial region of the 5'end of the norovirus ORF2 gene. RESULTS: A total of 259 (36.0%) of 719 specimens tested positive for norovirus by the reference method. The RGN RT-PCR assay detected norovirus in 244 (94%) of these 259 norovirus positive specimens. The sensitivity and specificity (95% confidence interval) of the RGN RT-PCR assay for detecting norovirus genogroup (G) I was 82.8% (63.5-93.5) and 99.1% (98.0-99.6) and for GII was 94.8% (90.8-97.2) and 98.6% (96.9-99.4), respectively. Seven specimens tested positive by the RGN-RT PCR that were negative by the reference method. The fifteen false negative samples were typed as GII.4 Sydney, GII.13, GI.3, GI.5, GI.2, GII.1, and GII.3 in the reference method. CONCLUSIONS: The RGN RT-PCR assay had a high sensitivity and specificity for the detection of norovirus in stool specimens from patients with sporadic AGE.

Dra/AfaE adhesin of uropathogenic Dr/Afa+ Escherichia coli mediates mortality in pregnant rats.

Escherichia coli bearing adhesins of the Dr/Afa family frequently causes urogenital infections during pregnancy in humans and has been associated with mortality in pregnant rats. Two components of the adhesin, Dra/AfaE and Dra/AfaD, considered virulence factors, are responsible for bacterial binding and internalization. We hypothesize that gestational mortality caused by Dr/Afa+ E. coli is mediated by one of these two proteins, Dra/AfaE or Dra/AfaD. In this study, using afaE and/or afaD mutants, we investigated the role of the afaE and afaD genes in the mortality of pregnant rats from intrauterine infection. Sprague-Dawley rats, on the 17th day of pregnancy, were infected with the E. coli afaE+ afaD and afaE afaD+ mutants. The clinical E. coli strain (afaE+ afaD+) and the afaE afaD double mutant were used as positive and negative controls, respectively. The mortality rate was evaluated 24 h after infection. The highest maternal mortality was observed in the group infected with the afaE+ afaD+ strain, followed by the group infected with the afaE+ afaD strain. The mortality was dose dependent. The afaE afaD double mutant did not cause maternal mortality, even with the highest infection dose. The in vivo studies corresponded with the invasion assay, where the afaE+ strains were the most invasive (afaE+ afaD strain > afaE+ afaD+ strain), while the afaE mutant strains (afaE afaD+ and afaE afaD strains) seemed to be noninvasive. This study shows for the first time that the afaE gene coding for the AfaE subunit of Dr/Afa adhesin is involved in the lethal outcome of gestational infection in rats. This lethal effect associated with AfaE correlates with the invasiveness of afaE+ E. coli strains in vitro.

Dr operon-associated invasiveness of Escherichia coli from pregnant patients with pyelonephritis.

We used a gentamicin protection assay to assess the ability of gestational pyelonephritis isolates of Escherichia coli to invade HeLa cells. The ability to enter HeLa cells was strongly associated with the presence of Dr operons coding for Dr adhesins. In contrast, the nonivasive isolates predominantly expressed papG, coding for P fimbriae.

Rapid receptor-clustering assay to detect uropathogenic and diarrheal Escherichia coli isolates bearing adhesins of the Dr family.

Infections caused by Escherichia coli isolates expressing adhesins of the Dr family are associated with diarrhea and urinary tract infections, and these E. coli strains recognize the complement regulatory protein decay-accelerating factor (DAF) as their receptor. Clustering of the DAF receptor at the sites of bacterial adherence to epithelial cells is proposed as an alternative to PCR assay for rapid detection of Dr-positive E. coli.

Characterization of AfaE adhesins produced by extraintestinal and intestinal human Escherichia coli isolates: PCR assays for detection of Afa adhesins that do or do not recognize Dr blood group antigens.

Operons of the afa family are expressed by pathogenic Escherichia coli strains associated with intestinal and extraintestinal infections in humans and animals. The recently demonstrated heterogeneity of these operons (L. Lalioui, M. Jouve, P. Gounon, and C. Le Bouguénec, Infect. Immun. 67:5048-5059, 1999) was used to develop a new PCR assay for detecting all the operons of the afa family with a single genetic tool. This PCR approach was validated by investigating three collections of human E. coli isolates originating from the stools of infants with diarrhea (88 strains), the urine of patients with pyelonephritis (97 strains), and the blood of cancer patients (115 strains). The results obtained with this single test and those previously obtained with several PCR assays were closely correlated. The AfaE adhesins encoded by the afa operons are variable, particularly with respect to the primary sequence encoded by the afaE gene. The receptor binding specificities have not been determined for all of these adhesins; some recognize the Dr blood group antigen (Afa/Dr(+) adhesins) on the human decay-accelerating factor (DAF) as a receptor, and others (Afa/Dr(-) adhesins) do not. Thus, the afa operons detected in this study were characterized by subtyping the afaE gene using specific PCRs. In addition, the DAF-binding capacities of as-yet-uncharacterized AfaE adhesins were tested by various cellular approaches. The afaE8 subtype (Afa/Dr(-) adhesin) was found to predominate in afa-positive isolates from sepsis patients (75%); it was frequent in afa-positive pyelonephritis E. coli (55.5%) and absent from diarrhea-associated strains. In contrast, Afa/Dr(+) strains (regardless of the afaE subtype) were associated with both diarrhea (100%) and extraintestinal infections (44 and 25% in afa-positive pyelonephritis and sepsis strains, respectively). These data suggest that there is an association between the subtype of AfaE adhesin and the physiological site of the infection caused by afa-positive strains.

Role of decay-accelerating factor domains and anchorage in internalization of Dr-fimbriated Escherichia coli.

Dr-fimbriated Escherichia coli capable of invading epithelial cells recognizes human decay-accelerating factor (DAF) as its cellular receptor. The role of extracellular domains and the glycosylphosphatidylinositol anchor of DAF in the process of internalization of Dr(+) E. coli was characterized in a cell-cell interaction model. Binding of Dr(+) E. coli to the short consensus repeat 3 domain of DAF expressed by Chinese hamster ovary cells was critical for internalization to occur. Deletion of short consensus repeat 3 domain or replacement of Ser(165) by Leu in this domain, or the use of a monoclonal antibody to this region abolished internalization. Replacing the glycosylphosphatidylinositol anchor of DAF with the transmembrane anchor of membrane cofactor protein or HLA-B44 resulted in abolition or reduction of internalization respectively. Cells expressing glycosylphosphatidylinositol-anchored DAF but not the transmembrane-anchored DAF internalized Dr(+) E. coli through a glycolipid pathway, since the former cells were more sensitive to inhibition by methyl-beta-cyclodextrin, a sterol-chelating agent. Electron microscopic studies revealed that the intracellular vacuoles containing the internalized Dr(+) E. coli were morphologically distinct between the anchor variants of DAF. The cells expressing glycosylphosphatidylinositol-anchored DAF contained a single bacterium in tight-fitting vacuoles, while the cells expressing transmembrane-anchored DAF contained multiple (two or three) bacteria in spacious phagosomes. This finding suggests that distinct postendocytic events operate in the cells expressing anchor variants of DAF. We provide direct evidence for the DAF-mediated internalization of Dr(+) E. coli and demonstrate the significance of the glycosylphosphatidylinositol anchor, which determines the ability and efficiency of the internalization event.

Experimental transmission of Neisseria gonorrhoeae from pregnant rat to fetus.

Sprague-Dawley rats were infected on day 20 of pregnancy by intraperitoneal inoculation with Neisseria gonorrhoeae. Disseminated gonococcal infection (DGI) and pelvic inflammatory disease (PID) strains in the presence of C1q but not in the presence of bovine serum albumin (BSA) were able to spread from the pregnant rat to the fetus and resulted in fetal mortality. Transmission of DGI and PID strains that are serum resistant (ser(r)) and sac-4 positive but not of a local infection strain that is ser(s) and sac-4 negative was facilitated by the C1q-dependent mechanism. This study provides the first experimental model that may mimic the transmission of gonococcal infection from mother to the fetus during pregnancy.

Decay-accelerating factor and cytoskeleton redistribution pattern in HeLa cells infected with recombinant Escherichia coli strains expressing Dr family of adhesins.

Escherichia coli strains expressing Dr fimbriae are able to enter epithelial cells by interacting with a complement-regulatory protein, decay-accelerating factor. This model of bacterial internalization, with a well-characterized bacterial ligand and host receptor, provides a unique opportunity to investigate the early stages of invasion. We used immunofluorescence staining techniques to examine the distribution of receptor and cytoskeletal proteins in HeLa cells infected with E. coli recombinant strains that expressed Dr family of adhesins: Dr, Dr-II, F1845, AFA-I, and AFA-III. A major rearrangement of decay-accelerating factor was found at the adherence sites of recombinant strains expressing Dr, Dr-II, and F1845 adhesins. The changes in the distribution of receptor were significantly smaller on HeLa cells infected with E. coli bearing AFA-I or AFA-III afimbrial adhesins. Receptor aggregation was associated with the redistribution of cytoskeleton-associated proteins such as actin, alpha-actinin, ezrin, and occasionally tropomyosin. Purified Dr fimbriae coated on polystyrene beads were capable of triggering clustering of receptor and accumulating actin at the adhesion sites of beads to HeLa cells. Using scanning and transmission electron microscopic techniques, we have shown that beads coated with Dr fimbriae, as opposed to beads coated with bovine serum albumin, were enwrapped by cellular microvilli and ultimately internalized into HeLa cells. This indicates that interaction of Dr fimbriae with decay-accelerating factor is associated with redistribution of receptor and is sufficient to promote bacterial internalization.

Dr fimbriae operon of uropathogenic Escherichia coli mediate microtubule-dependent invasion to the HeLa epithelial cell line.

Escherichia coli Dr adhesin and decay-accelerating factor (DAF) receptor-mediated interaction was proposed as the mechanism of ascending urinary tract infection (UTI) and chronic interstitial nephritis. This report provides novel evidence for Dr fimbriae operon-mediated invasive capacity of Dr+ E. coli. Insertional mutants draE, draC, and draB, and adherent draD and UV-inactivated BN406 were unable to enter HeLa cells. Complementation of the dra mutation restored invasiveness. Internalization was inhibited by anti-Dr fimbriae IgG (100%), anti-SCR-3 domain of DAF (75%), and nocodazole (95%). Increased receptor-ligand density occurred at the site of internalization. Internalized Dr+ E. coli did not significantly multiply in the HeLa cell line. Accordingly, the dra operon and DAF were required for microtubule-dependent internalization of E. coli to HeLa cells. The relatively low invasion and multiplication rates of Dr+ E. coli may hypothetically contribute to the postattachment steps of ascending UTI and chronic renal infection.

Development of experimental model of chronic pyelonephritis with Escherichia coli O75:K5:H-bearing Dr fimbriae: mutation in the dra region prevented tubulointerstitial nephritis.

Escherichia coli that express Dr fimbriae and related adhesins recognize the common receptor decay accelerating factor. E. coli strains that express adhesins of the Dr family were postulated to be associated with cystitis (30-50%), pregnancy-associated pyelonephritis (30%), and chronic diarrhea (50%). In this study, we investigated the hypothesis that E. coli renal interstitial binding mediated by the Dr adhesin may be important for the development of chronic pyelonephritis. An insertional dra mutant, E. coli DR14, of the clinical E. coli isolate IH11128 bearing Dr fimbriae, was constructed and used to characterize persistence of infection and interstitial tropism in an experimental model of ascending pyelonephritis. Quantitative cultures of kidney homogenates indicated that Dr hemagglutinin positive (Dr+) E. coli IH11128 established a 1-yr colonization of renal tissue. In the Dr hemagglutinin negative (Dr-) group, 50% of animals cleared infection within 20 wk and 100% between 32 to 52 wk. Dr+ E. coli colonized the renal interstitium. Significant histological changes corresponding to tubulointerstitial nephritis including interstitial inflammation, fibrosis, and tubular atrophy were found in the kidney tissue of the Dr+ but not the Dr- group. A substantial amount of fimbrial antigen was detected in the parenchymal regions affected by interstitial inflammation and fibrosis. The obtained results are consistent with the hypothesis that mutation within the dra region, affecting E. coli binding to tubular basement membranes, prevented renal interstitial tropism and the development of the changes characteristically seen in tubulointerstitial nephritis.