Detection of Helicobacter pylori by PCR but not culture in water and biofilm samples from drinking water distribution systems in England

AIMS

To investigate treated water distribution systems in England as a source of Helicobacter pylori.

METHODS AND RESULTS

Water and biofilms were obtained from 11 domestic and seven educational properties and from hydrants, reservoirs and water meters supplied by three water utilities. Samples were cultured on nonselective and antibiotic containing media combined with immunomagnetic separation concentration. Viable helicobacters were not detected in any of the 151 samples but Helicobacter-specific PCR assays detected DNA in 26% of samples from domestic properties, schools and hydrants with the highest frequency in biofilms (42%). Direct sequencing of six selected amplicons confirmed >95% sequence homology to H. pylori.

CONCLUSIONS

While viable helicobacters were not isolated, evidence was obtained for the presence of Helicobacter DNA, including that of H. pylori. Biofilms on surfaces within water distribution systems may act either as sites for the passive accumulation of helicobacters or as potentially important reservoirs of infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our findings strengthen evidence that H. pylori may be transmitted through drinking water. However, there is currently no evidence that viable cells can survive the disinfection levels used in UK mains supplies and the health risk from this source remains unclear.

Identification of enteropathogenic Escherichia coli isolated in Britain as enteroaggregative or as members of a subclass of attaching-and-effacing E. coli not hybridising with the EPEC adherence-factor probe

Strains of Escherichia coli from sporadic cases of diarrhoea and belonging to serotypes O44:H18, O55:H7, O111ab:H21, O111ab:H25 or O126:H27 were examined for virulence properties. With the exception of O111ab:H25 these are considered to be classical enteropathogenic E. coli (EPEC) serotypes. The strains had been isolated in Britain from the faeces of children less than 3 years old. Of the serotypes examined, 7 of 13 O44:H18 strains, all of 10 O111ab:H21 strains and 13 of 21 O126:H27 strains belonged to the enteroaggregative class of E. coli (EAggEC) that attached to HEp-2 cells in the characteristic aggregative pattern and hybridised with the EAggEC probe. They also caused mannose-resistant haemagglutination of rat erythrocytes, a property which may be a useful marker for their identification. Strains of O44:H18 with similar properties were also isolated from three small outbreaks in Britain, one of which involved elderly patients. EAggEC have not been considered previously as aetiological agents of diarrhoea in developed countries and have rarely been reported as belonging to EPEC serotypes. All 15 O55:H7 strains and seven of eight O111ab:H25 strains were also considered to be potentially diarrhoeagenic as they gave localised attachment (LA) to HEp-2 cells that resulted in a positive fluorescence actin-staining test. This test is considered to correlate with the attaching-and-effacing virulence mechanisms of EPEC in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Human lymphocyte heme oxygenase 1 as a response biomarker to inorganic arsenic

We propose the use of human lymphocyte heme oxygenase 1 (HO1) as a biomarker of response to environmental arsenic exposure. We report the induction of HO1 in human lymphoblastoid cells (LBs) by arsenite in a dose-related manner. HO1 was identified by SDS-PAGE from its molecular weight and from its detection by Western blotting with anti-HO1. HO1 levels in LBs treated with arsenite increased by de novo synthesis as demonstrated by incorporation of 35S-methionine and by inhibition of HO1 synthesis by actinomycin D. The amount of HO1 in LBs was estimated by quantifying Western blots. HO1 was also induced by 10 microM cadmium or mercuric chloride. We suggest that circulating lymphocyte HO1 levels may be useful in assessing the biological activity of arsenic exposure in vivo under properly controlled conditions of simultaneous urinalysis for arsenic, cadmium, and mercury.

Virulence properties of Escherichia coli strains belonging to serogroups O26, O55, O111 and O128 isolated in the United Kingdom in 1991 from patients with diarrhoea

Some strains of Escherichia coli belonging to serogroups O26, O55, O111 or O128 produce Vero cytotoxin (VT). These serogroups are included in the range of enteropathogenic E. coli (EPEC) serogroups for which commercial antisera are available. In an attempt to obtain information on VT-producing strains other than those of serogroup O157, 122 strains belonging to these four serogroups and isolated in 1991 from patients with diarrhoea in the United Kingdom were tested for hybridization with VT probes. Only 18 of the 122 strains were VT-positive and these were O26 or O128. However 90 strains hybridized with the E. coli attaching and effacing (eae) probe (including 14 VT-positive strains) and 17 with the enteroaggregative E. coli (EAggEC) probe. For 78 eae-positive and 9 EAggEC-positive strains, tissue culture tests correlated with the probe results as the strains gave, respectively, either localized adhesion and a positive fluorescent-actin staining test or a characteristic aggregative attachment. A total of 111 of the 122 strains belonging to serogroups O26, O55, O111 or O128 possessed properties that may be associated with the ability to cause human diarrhoeal disease, and similar studies are needed on strains from the other classical EPEC serogroups.

Use of gene probes and adhesion tests to characterise Escherichia coli belonging to enteropathogenic serogroups isolated in the United Kingdom

Nine hundred and twenty-five Escherichia coli isolates from cases of diarrhoea in the United Kingdom and belonging to enteropathogenic E. coli (EPEC) O serogroups were examined for virulence properties. The tests included adhesion to HEp-2 cells, the fluorescence actin staining (FAS) test (which correlates with the ability to cause attaching and effacing lesions) and DNA hybridisations with probes to detect sequences for eaeA (E. coli attaching and effacing factor), EAF (EPEC adherence factor), verocytotoxins VT1 and VT2, enteroaggregative E. coli and diffusely adherent E. coli. The O serogroups examined were 18, 26, 44, 55, 86, 111, 114, 119, 125, 126, 127, 128 and 142. Six hundred and sixty strains (71.4%) hybridised with at least one of the DNA probes. Over 80% of strains in O serogroups 26, 55, 119, 125, 127 and 142 and 41% of strains of serogroups 86, 111, 114, 126 and 128 hybridised with the eae probe and most showed localised attachment and were FAS-positive. However, <10% of these eae probe-positive strains hybridised with the EAF probe. Eighty-four of 232 strains in O serogroups 44, 86, 111, and 126 were enteroaggregative. VT genes were detected in 57 of 402 strains in O serogroups 26, 55, 111 and 128. Identification of EPEC by serogrouping was shown to be an effective method of identifying strains with pathogenic potential, although the organisms were diverse in their properties.

Mutational analysis of the L1 binding site of 23S rRNA in Escherichia coli

The L11 ribosomal protein operon of Escherichia coli contains the genes for L11 and L1 and is feedback regulated by the translational repressor L1. Both the L1 binding site on 23S rRNA and the L1 repressor target site on L11 operon mRNA share similar proposed secondary structures and contain some primary sequence identity. Several site-directed mutations in the binding region of 23S rRNA were constructed and their effects on binding were examined. For in vitro analysis, a filter binding method was used. For in vivo analysis, a conditional expression system was used to overproduce a 23S rRNA fragment containing the L1 binding region, which leads to specific derepression of the synthesis of L11 and L1. Changes in the shared region of the 23S rRNA L1 binding site produced effects on L1 binding similar to those found previously in analysis of corresponding changes in the L11 operon mRNA target site. The results support the hypothesis that r-protein L1 interacts with both 23S rRNA and L11 operon mRNA by recognizing similar features on both RNAs.

Digital health in the era of COVID-19: Reshaping the next generation of healthcare

COVID-19 is one of the most deadly diseases to have stricken us in recent decades. In the fight against this disease, governments and stakeholders require all the assistance they can get from various systems, including digital health interventions. Digital health technologies are supporting the tracking of the COVID-19 outbreak, diagnosing patients, expediting the process of finding potential medicines and vaccines, and disinfecting the environment, The establishment of electronic medical and health records, computerized clinical decision support systems, telemedicine, and mobile health have shown the potential to strengthen the healthcare system. Recently, these technologies have aided the health sector in a variety of ways, including prevention, early diagnosis, treatment adherence, medication safety, care coordination, documentation, data management, outbreak tracking, and pandemic surveillance. On the other hand, implementation of such technologies has questions of cost, compatibility with existing systems, disruption in patient-provider interactions, and sustainability, calling for more evidence on clinical utility and economic evaluations to help shape the next generation of healthcare. This paper argues how digital health interventions assist in the fight against COVID-19 and their opportunities, implications, and limitations.

Identification of Escherichia coli that produces heat-stable enterotoxin STA by a commercially available enzyme-linked immunoassay and comparison of the assay with infant mouse and DNA probe tests

By using the infant mouse test and a commercially available competitive enzyme-linked immunosorbent assay (ELISA), 100 strains of Escherichia coli carrying STA1 or STA2 genes were shown to produce the heat-stable enterotoxin STA. An additional 100 strains were negative in both tests. The ELISA was easy to perform, and results were available within 24 h. Testing strains with an enzyme-linked DNA probe kit that incorporated both STA1- and STA2-specific oligonucleotides showed that the 100 strains positive in the mouse test and ELISA also hybridized with the mixed probe. Two strains carrying STA1 genes but negative in the mouse test and ELISA also hybridized with the mixed probe.

Detection and differentiation of the gene for toxin co-regulated pili (tcpA) in Vibrio cholerae non-O1 using the polymerase chain reaction

The polymerase chain reaction has been used to differentiate the gene which encodes the toxin co-regulated pili (tcpA) of the El Tor and classical biotypes of Vibrio cholerae O1. The same PCR primers were applied to strains belonging to non-O1 serogroups that produced cholera toxin. The size of fragment amplified was either identical to the tcpA of biotype El Tor (471 bp) or to the tcpA of biotype classical (617 bp). All strains belonging to the novel epidemic serogroup O139 generated a 471-bp fragment identical to El Tor tcpA. The present study suggests that there may be an association between non-O1 serogroup and tcpA type.

Heterogeneity in expression of lipopolysaccharides by strains of Escherichia coli O157

A total of 47 strains of Escherichia coli belonging to serogroup O157 were examined for the expression of long-chain lipopolysaccharide (LPS) by means of SDS-PAGE and silver staining. Strains belonged to 10 different flagellar (H) types or did not express flagella. Nine strains carried genes encoding Vero cytotoxin (VT). Strains of E. coli O157 expressed one of three LPS SDS-PAGE profiles designated A, B and C. Strains expressing profile A belonged to H-types 6 and 19, while those expressing LPS profile B belonged to H-types 2, 16, 20, 39, 42 and 45. Strains of E. coli expressing profile C belonged to H-types 7 and 8; strains producing VT expressed LPS profile C only, although not all strains with H-types 7 and 8 carried genes for VT. Regardless of H-type or the LPS profile expressed, serum antibodies produced by patients infected with strains of E. coli belonging to serogroup O157 would be detected by serological tests.

Ferumoxide-enhanced MRI in patients with colorectal cancer and rising CEA: surgical correlation in early recurrence

The purpose of this study was to evaluate the value of Ferumoxide-enhanced magnetic resonance (MR) imaging in the detection of hepatic metastases in high-risk patients treated for colorectal cancer that have rising CEA. We used 19 patients treated previously for colorectal cancer with rising CEA levels underwent an unenhanced T(1)-weighted (T1W), T(2)-weighted (T2W), STIR, and Ferumoxide-enhanced hepatic MRI. Following these studies, a laparotomy was performed and the liver was evaluated by palpation and intraoperative ultrasound. Two observers who were blinded to surgical results evaluated each MR sequence separately. The number of lesions considered highly suspicious for metastatic lesions were determined for each sequence and were compared to the results of surgery. The McNemar test was used to compare the outcomes of the different sequences. MR Imaging was unable to detect small (<5 mm) metastases discovered at surgery. The best non-contrast sequences for detecting metastases were the STIR with 42% sensitivity, 83% specificity and an overall accuracy of 56% and the T1W sequence (sensitivity 38%, specificity 100%, accuracy 57%), which were not significantly different (p 0.4). The noncontrast T2W sequence had a sensitivity of 29% and a specificity of 77% with an overall accuracy of 46%. When all pre contrast scans were grouped together the common sensitivity was 42%, specificity was 77% and accuracy was 54%. The post-ferumoxide T(2)W scans had a sensitivity of 42%, specificity of 85%, and accuracy of 57%, but did not detect any additional lesions. There was no statistical difference between the pre- and post-contrast studies with regard to identifying patients with metastatic disease (p 0.1). In conclusion, we found small hepatic metastases in patients with early signs of recurrent colorectal cancer are difficult to detect on MRI. Ferumoxide-enhanced MRI was unable to detect additional hepatic metastases and performed no better than unenhanced MRI in detecting small hepatic metastasis.

COVID-19 and Health Sector Development Plans in Africa: The Impact on Maternal and Child Health Outcomes in Uganda

INTRODUCTION

Health Sector Development Plans (HSDPs) aim to accelerate movement towards achieving sustainable development goals for health, reducing inequalities, and ending poverty. Reproductive, maternal, newborn and child health (RMNCH) services are vulnerable to economic imbalances, including health insecurity, unmet need for healthcare, and low health expenditure. The same vulnerability influences the potential of a country to combat global outbreaks such as the COVID-19. We aimed to provide some important insights into the impacts of COVID-19 on RMNCH indicators and outcomes of the HSDP in Uganda.

METHODS

We conducted a descriptive study of secondary data obtained from the Ugandan government-led portals, supplemented by analyses of relevant articles published up to 06 May 2021 and deposited in PubMed.

RESULTS

Through synthesizing actionable and relevant evidence, we realized that RMNCH in Uganda is highly affected by the COVID-19 pandemic and the lockdown measures. The impact was across immunization, antenatal, sexual and reproductive health, emergency and obstetric, and postnatal care services. There was a decline sharply by 9.6% for under-five vitamin A coverage, 9% for DPT3HibHeb3 coverage, 6.8% for measles vaccination coverage, 6% for isoniazid preventive therapy coverage, and 3% for facility-based deliveries. Maternal and under-five deaths increased by 7.6% and 4%, respectively. Outreaches were rarely conducted in the lockdown period.

CONCLUSION

The COVID-19 pandemic has created a multitude of questions regarding the optimal policies to mitigate the disease while minimizing the unintended detrimental consequences of RMNCH. The lockdown restrictions threatened to reverse the progress made on the national HSDP for RMNCH. In Uganda, where young women are vulnerable to early marriage, unintended pregnancies, and unsafe abortion, access to RMNCH services should continue regardless of the COVID-19 status in the country. We urge that Uganda and other African countries should build resilient and sustainable health systems that can withstand emerging diseases like the COVID-19.

Effect of 5-methylcytosine as a neighboring base on methylation of DNA guanine by N-methyl-N-nitrosourea

Effects on N-methyl-N-nitrosourea (MNU) mediated methylation of the N7 position of guanine were compared in defined sequences of DNA containing cytosine or 5-methylcytosine (5mC) using a Maxam-Gilbert sequencing technique. Cytosine methylation in 5'-CpG-3' pairs within a subcloned fragment of the 5' region of the human HPRT gene was generated with SssI methylase and S-adenosylmethionine. Cytosine methylation was demonstrated by both the inhibition of DNA restriction by methylation sensitive endonucleases and the lack of cleavage at 5-methylcytosines by hydrazine. MNU-dependent methylation of the N7 position of guanine was inhibited up to 18% when 5mC was a 5' neighboring base to guanine and was inhibited up to 36% in an alternating CpG region in which both 5' and 3' neighboring bases of guanine were enzymatically altered to 5mC. It can be concluded that 5-methylcytosine has discernible effects on MNU methylation of the N7 position of specific guanine bases in DNA.

The use of gene probes, immunoassays and tissue culture for the detection of toxin in Vibrio cholerae non-O1

Vibrio cholerae non-O1 strains were screened for the presence of cholera enterotoxin (CT) genes by means of digoxigenin-labelled polynucleotide CTA and CTB probes. In-vitro production of CT was investigated by the Y1 mouse adrenal cell assay, enzyme-linked immunosorbent assay (ELISA) and a commercial, reversed passive latex agglutination (RPLA) kit. Only two (0.25%) of 790 strains tested gave positive results with the CTA and CTB probes. The production of other bacterial cytotoxin(s) made it impossible to use the characteristic cell-rounding effect on Y1 cells for the detection of CT. CT production by the probe-positive strains was confirmed by the immunoassays. Two hundred and fifty-two of the 788 probe-negative strains were tested by both cell assay and immunoassays. Of these, 90% produced cytotoxin(s) in the cell assay. In addition, 37% gave positive results in CT-ELISA, but negative results with LT-ELISA and VET-RPLA. These results indicate the presumed presence of a toxin in V. cholerae non-O1 that is able to bind GM1 and react with antisera to CT, but which is not identical to CT.

Nearest neighbor effects on carcinogen binding to guanine runs in DNA

A synthetic DNA fragment was constructed to determine the effect of 5' and 3' neighbors of guanine runs on the binding of chemical carcinogens. Determinations were made on the relative intensity of reactivity between aflatoxin B1 or benzo(a)pyrene and methylnitrosourea or 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea with various guanine positions in an endlabeled DNA fragment of known sequence. After reaction, the fragments were depurinated to produce strand breaks to allow Maxam and Gilbert sequencing for guanine positions. Relative reaction intensities were compared densitometrically. 3' neighbors exerted greater influence on carcinogen binding than did 5' neighbors, the influence extended only to the adjacent guanine and depended upon the chemical nature of the carcinogen. In addition, the presence of one carcinogen adduct in the guanine run influenced the formation of a subsequent adduct when the DNA was exposed to a second carcinogen, and this effect also depended on the nature of the second carcinogen. The results suggest that DNA adduct formation in the presence of multiple carcinogens is more complicated than an additive mechanism would suggest.

5-Methylcytosine in CpG sites and the reactivity of nearest neighboring guanines toward the carcinogen aflatoxin B1-8,9-epoxide

The reactivity of guanines in an oligonucleotide containing mutational hot spots within the p53 gene (codons 248 and 249), 5'-CCG1G2AG3G4CCCA-3', toward dimethyl sulfate (DMS) and aflatoxin B1-8,9-epoxide (AFB1-8,9-epoxide) was investigated by a modified Maxam-Gilbert technique. 5-Methylcytosine in the CpG site of codon 248 did not appear to modulate the reactivity of target guanines G1, G2, G3, and G4 toward either genotoxin when compared to the sequence containing a nonmethylated CpG site. A similar experiment was conducted in which a 0.5-kb fragment of the human HPRT gene containing exon 1 and several CpG sites was treated with UV-activated aflatoxin B1. Results showed that guanine adduct formation was independent of the methylation status of the CpG site. These findings are discussed in relation to other studies that have shown that cytosine methylation has an inhibiting effect, an enhancing effect, or no effect on adduct formation with nearby guanine nucleotides.

Molecular bacterial load assay versus culture for monitoring treatment response in adults with tuberculosis

The lack of rapid, sensitive, and deployable tuberculosis diagnostic tools is hampering the early diagnosis of tuberculosis and early detection of treatment failures. The conventional sputum smear microscopy or Xpert MTB/RIF assay cannot distinguish between alive and dead bacilli and the culture method delays providing results. Tuberculosis molecular bacterial load assay is a reverse transcriptase real-time quantitative polymerase chain reaction that quantifies viable tuberculosis bacillary load as a marker of treatment response for patients on anti-tuberculosis therapy. However, results are not synthesized enough to inform its comparative advantage to tuberculosis culture technique which is yet the gold standard of care. With this review, we searched electronic databases, including PubMed, Embase, and Web of Science, from March 2011 up to February 2021 for clinical trials or prospective cohort studies that compared tuberculosis molecular bacterial load assay with tuberculosis culture in adults. We included eight studies that meet the inclusion criteria. Tuberculosis molecular bacterial load assay surpasses culture in monitoring patients with tuberculosis during the first few weeks of anti-tuberculosis treatment. It is more desirable over culture for its shorter time to results, almost zero rates of contamination, need for less expertise on the method, early rate of decline, lower running cost, and reproducibility. Its rapid and specific tuberculosis treatment monitoring competency benefits patients and healthcare providers to monitor changes of bacillary load among isolates with drug-susceptible or resistance to anti-tuberculosis regimens. Despite of the high installing cost of the tuberculosis molecular bacterial load assay method, molecular expertise, and a well-equipped laboratory, tuberculosis molecular bacterial load assay is a cost-effective method with comparison to culture in operational running. To achieve maximum utility in high tuberculosis burden settings, an intensive initial investment in nucleic acid extraction and polymerase chain reaction equipment, training in procedures, and streamlining laboratory supply procurement systems are crucial. More evidence is needed to demonstrate the potential large-scale and sustainable use of tuberculosis molecular bacterial load assay over culture in resource-constrained settings.

Somatosensory evoked potential, neurological examination and magnetic resonance imaging for assessment of cervical spinal cord decompression

The present study was designed to determine the relationship between neurological testing, anatomical imaging, and electrophysiological monitoring for assessing outcome of cervical spinal cord decompression. We prospectively studied 28 consecutive patients (age 39-76 yr) who were subjected to presurgical-(1-3 wk) and postsurgical (3-4 mo) neurological examination and recording of the median nerve somatosensory evoked potential (SEP). In 13 patients, magnetic resonance imaging (MRI) was also performed. Changes in neurological function, SEP and MRI were evaluated and graded as (1) improvement,(2) no change or (3) deterioration. Neurological outcome (NO) was based on changes in motor grade strength, sensory, reflexes and gait. The SEP outcome was based on changes in latency and disappearance of SEP waveform components whereas MRI evaluation was based on changes in spinal cord and canal diameters. Significance of association between NO, SEP and MRI was determined by Pearson's Chi-Square statistic (P<.05). The SEP improved in 71% (20/28) and deteriorated in 28% (8/28) of the subjects. An association between SEP changes and NO was found in 82% (23/28) of the subjects (P = .0038). Decompression increased the spinal canal diameter in 92% (12/13), and the spinal cord diameter in 38% (5/13) of the subjects. An association between NO, or SEP and MRI was not detected. Changes in median nerve SEP latency appear to be predictive of the neurological status of patients subjected to cervical spinal cord decompression. Postoperative increments in SEP latency or disappearance of the SEP waves were indicative of poor outcome after surgical decompression of the cervical spinal cord.

DNA-damaging effects of genotoxins in mixture: modulation of covalent binding to DNA

Modulation of DNA adduct formation by pre-existing adducts was examined in synthetic oligonucleotides and genomic DNA (calf thymus); genotoxins studied were N-acetoxy-acetylaminofluorene (N-AcO-AAF), aminofluorene (AF), aflatoxin B1-8,9-epoxide (AFB1-8,9-epoxide), and dimethylsulfate (DMS). Oligodeoxynucleotides containing either guanine-C8-AAF (Gua-C8-AAF) or Gua-C8-AF adducts and a neighboring unadducted guanine (G) (target G), located 1, 2, or 4 nucleotides from the adduct, were reacted, as single- (ss) or double-stranded (ds) substrates, with dimethylsulfate (DMS) or AFB1-8,9-epoxide. A modified Maxam-Gilbert technique showed that the presence of the AAF adduct lowered the extent to which AFB1-8,9-epoxide, but not DMS, reacted with target G. Binding of AFB1-8,9-epoxide to the target G was attenuated (> or =5-fold) when the target was located immediately adjacent to an AAF, but not AF, adduct in ds-DNA. Reaction with AFB1-8,9-epoxide increased when the target G was located 2 or 4 nucleotides from the AAF adduct. Pretreatment of calf thymus DNA with AAF (0-1.8% nucleotides modified) reduced levels of Gua-N7-AFB1 adducts formed after subsequent treatment with AFB1-8,9-epoxide. Pretreatment of calf thymus DNA with AFB1 did not alter levels of adducts formed after subsequent treatment with N-AcO-AAF. The supposition that aflatoxin B1-binding to DNA may be altered by conformational changes in the helix, due to the presence of a pre-existing AAF adduct, is supported by the absence of an effect by AF and confirmation of local denaturation of the oligomer helix by use of chemical probes hydroxylamine and diethylpyrocarbonate. Nonetheless, the importance of changes in the nucleophilicity of neighboring nucleotides and local steric effects cannot be ruled out.