Personalized management of patients with inoperable alveolar echinococcosis undergoing treatment with albendazole: usefulness of positron-emission-tomography combined with serological and computed tomography follow-up

The present study aimed to identify a sub-group of inoperable alveolar echinococcosis (AE) patients undergoing long-term treatment with benzimidazole (BZM) who presented with an evolution suggestive of a parasitocidal effect. An evolution compatible with parasite death was observed in five patients.

Review article: the utility of reagent strips in the diagnosis of infected ascites in cirrhotic patients

BACKGROUND

Spontaneous bacterial peritonitis (SBP) can be diagnosed via leucocyte esterase reagent strips, although diagnostic performances vary.

AIM

To perform critical review of literature on the use of reagent strips in SBP.

METHODS

Nineteen studies were analysed (Medline search), comparing reagent strips in cirrhotic ascites vs. cytobacteriological methods. Diagnostic grades (G) were: GO = 0 leucocytes/mm3; G1 = 15; G2 = 70; G3 = 125; G4 = 500 for Multistix, GO = 0; G1 = 25; G2 = 75; G3 = 500 for Nephur, Combur, UriScan, and GO = 0; G1 = 25; G2 = 75; G3 = 250; G4 = 500 for Aution.

RESULTS

Medians per study were: 75 patients (range: 31-1041), 136 ascites (47-2123), 17 SBP (5-117). For Multistix (12 studies), the sensitivities fell within the ranges 64.7-100% (G > or = 1), 45.7-83% (G > or = 2) and 45.3-89% (G > or = 3). For Nephur (n = 2), Combur (n = 6), UriScan (n = 1), sensitivities ranged 80.4-100% (G > or = 1), 63-100% (G > or = 2) and 67.7-97% (G > or = 3). For Aution (n = 3), sensitivities ranged 93-96% (G > or = 2) and 89% (G > or = 3). Nephur, Combur, UriScan displayed higher sensitivities than Multistix. However, in larger studies, sensitivities dramatically fell at 45.3% for Multistix (G > or = 3) if ascites polymorphonuclear count <1000/mm3 and 22.2% for bacterascites or 16.7-25% for asymptomatic patients.

CONCLUSION

Use of reagent strips for the diagnosis of SBP cannot be recommended, in view of low sensitivity and a high risk of false negatives, especially in patients with SBP and low polymorphonuclear count.

Coeliac disease in chronic hepatitis C: a French multicentre prospective study

BACKGROUND

A prevalence of 1.2% of coeliac disease (CD) in patients with chronic hepatitis C was recently reported, suggesting a possible epidemiological link between these two diseases. However, other studies have not found this relationship.

AIM

To conduct a French multicentre prospective study to assess the prevalence of CD in hepatitis C virus (HCV)-infected patients.

METHODS

Between June 2003 and November 2005, 624 consecutive HCV-positive out-patients were tested for antiendomysial IgA antibodies (AEA), antigliadin IgA and IgG antibodies (AGA). Patients with positive AEA or IgA AGA and positive IgG AGA in a context of a high suspicion of CD were asked to undergo gastroscopy with duodenal biopsies.

RESULTS

Isolated IgA AEA, IgA AGA and IgG AGA were 0.16%, 5.7% and 4.4%, respectively. Gastroscopy was required for 39 patients, 31 were performed (eight refusals), but only 25 duodenal biopsies were performed as six patients had cirrhosis. CD was never detected.

CONCLUSIONS

The prevalence of CD in HCV-positive patients was 0% (95% confidence interval: 0-0.59%), but there is a low prevalence of CD in the whole French population.

Interferon for interferon naive patients with chronic hepatitis C

BACKGROUND

A previous meta-analysis of interferon therapy in naive patients with chronic hepatitis C has documented its efficacy in achieving virologic clearance, and improving liver biochemistry and histology; however, since its publication additional trials have been reported.

OBJECTIVES

To evaluate the response to interferon in interferon naive patients with chronic hepatitis C. The effect of treatment dose and duration, and the response in patients with cirrhosis and those with normal aminotransferases was also investigated.

SEARCH STRATEGY

The Cochrane Controlled Trials Register (Cochrane Library Issue 1, 1999), MEDLINE (January 1966 to December 1999), and reference lists were searched, and pharmaceutical companies were contacted for unpublished trials.

SELECTION CRITERIA

Randomised clinical trials comparing interferon with placebo, no treatment, or different regimens of interferon were selected. Abstracts were excluded.

DATA COLLECTION AND ANALYSIS

The primary outcome measure was sustained disappearance of serum HCV RNA (virologic sustained response (SR)). Biochemical and end of treatment responses, liver histology, and adverse events were also recorded. Assessment of drug efficacy used the methods of Peto and Der Simonian and Laird.

MAIN RESULTS

Fifty-four trials enrolling 6545 patients were included. Compared with no treatment, interferon 3 MU thrice weekly for 12 months increased the probability of a virologic SR (Peto odds ratio (OR) 4.60; 95% confidence interval (CI) 1.53 to 13.85). At this dosage and duration of therapy, the rate of virologic SR was 17% (95% CI 10 to 28%) in interferon-treated patients versus 3% (95% CI 1 to 10%) in controls. A dose of 6 MU was more effective than 3 MU thrice weekly (OR for 12 months treatment, 2.21; 95% CI 1.10 to 4.45), as were durations of 12 months or greater versus six months (OR 1.87; 95% CI 1.30 to 2.67). Adverse events were more common with higher doses and prolonged durations of treatment. Compared with no therapy, interferon increased the probability of histologic improvement (OR 9.22; 95% CI 5.69 to 14.94). The response to interferon in cirrhotic patients (virologic SR, 17%; 95% CI 11 to 26%) was similar to that in non-cirrhotic patients. However, interferon was no more effective than control in patients with normal aminotransferases.

REVIEWER'S CONCLUSIONS

Interferon is effective in achieving viral clearance and improving liver biochemistry and histology in interferon naive patients with chronic hepatitis C. Higher doses and prolonged durations are more effective, but associated with more frequent adverse events. Interferon is associated with similar benefits in patients with cirrhosis, but the efficacy in patients with normal aminotransferases is unproven.

Interferon for acute hepatitis C

BACKGROUND

Acute hepatitis C virus (HCV) infection progresses to chronicity in the majority of patients. In order to prevent the progression to chronic disease, several studies have assessed interferon in patients with acute hepatitis C.

OBJECTIVES

The aim of this review was to assess the efficacy of interferon in acute HCV infection.

SEARCH STRATEGY

We searched MEDLINE, the Cochrane Controlled Trials Register, and the abstracts of the American Association for the Study of Liver Diseases (June 2001). We also contacted pharmaceutical companies to obtain unpublished trials.

SELECTION CRITERIA

Randomised clinical trials comparing interferon with placebo or no treatment, and published as an article, abstract, or letter were selected. No language limitations were used.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. The following endpoints were analysed: normalization of alanine aminotransferase (ALT) activity at the end of treatment (biochemical ETR); sustained ALT normalization at the end follow-up (biochemical SR); disappearance of serum HCV RNA by polymerase chain reaction assay at the end of treatment (virologic ETR) and at the end of follow-up (virologic SR). Histologic data and adverse events were also recorded. Assessment of drug efficacy used the methods of Peto and Der Simonian and Laird.

MAIN RESULTS

Six randomised trials involving 206 patients with acute hepatitis C met the inclusion criteria. Four trials assessing interferon alfa-2b in 141 patients, all with transfusion-acquired acute hepatitis C, were included. They demonstrated no significant heterogeneity in the outcomes assessed. When compared with no treatment, interferon alfa-2b was associated with an increase in the rates of virologic ETR and SR by 45% (95% CI 31-59%, P < 0.00001) and 29% (95% CI 14-44%, P = 0.0002), respectively. The virologic ETR was 42% (95% CI: 30-56%) in the interferon alfa-2b group versus 4% (95% CI 0-13%, P < 0.00001) in the control group. At the end of follow-up, a virologic SR was seen in 32% (95% CI 21-46%) of interferon-treated patients versus only 4% (95% CI 0-13%, P = 0.00007) of controls. The tolerability of therapy, or the impact of interferon alfa-2b on hepatic histology, was not reported. Two trials assessed interferon beta in a total 65 patients. The efficacy of interferon beta could not be assessed, however, due to heterogeneity of these trials.

REVIEWER'S CONCLUSIONS

Interferon alfa is effective in improving biochemical outcomes and achieving sustained virologic clearance in patients with transfusion-acquired acute hepatitis C. The effect on long-term clinical outcomes could not be assessed due to limitations in the current data.

The role of T cell subsets and cytokines in the pathogenesis of Helicobacter pylori gastritis in mice

Gastritis due to Helicobacter pylori in mice and humans is considered a Th1-mediated disease, but the specific cell subsets and cytokines involved are still not well understood. The goal of this study was to investigate the immunopathogenesis of H. pylori-induced gastritis and delayed-type hypersensitivity (DTH) in mice. C57BL/6-Prkdc(scid) mice were infected with H. pylori and reconstituted with CD4+, CD4-depleted, CD4+CD45RB(high), or CD4+CD45RB(low) splenocytes from wild-type C57BL/6 mice or with splenocytes from C57BL/6(IFN-gamma-/-) or C57BL/6(IL-10-/-) mice. Four or eight weeks after transfer, DTH to H. pylori Ags was determined by footpad injection; gastritis and bacterial colonization were quantified; and IFN-gamma secretion by splenocytes in response to H. pylori Ag was determined. Gastritis and DTH were present in recipients of unfractionated splenocytes, CD4+ splenocytes, and CD4+CD45RB(high) splenocytes, but absent in the other groups. IFN-gamma secretion in response to H. pylori Ags was correlated with gastritis, although splenocytes from all groups of mice secreted some IFN-gamma. Gastritis was most severe in recipients of splenocytes from IL-10-deficient mice, and least severe in those given IFN-gamma-deficient splenocytes. Bacterial colonization in all groups was inversely correlated with gastritis. These data indicate that 1) CD4+ T cells are both necessary and sufficient for gastritis and DTH due to H. pylori in mice; 2) high expression of CD45RB is a marker for gastritis-inducing CD4+ cells; and 3) IFN-gamma contributes to gastritis and IL-10 suppresses it, but IFN-gamma secretion alone is not sufficient to induce gastritis. The results support the assertion that H. pylori is mediated by a Th1-biased cellular immune response.

Polymorphonuclear leukocyte-elastase in Crohn's disease: correlation with 99mtechnetium hexamethyl propylene amine oxime leukocyte scintigraphy

In Crohn's disease (CD), labeled leukocyte scintigraphy results are highly correlated with radioendoscopic findings and the degree of histologic inflammation. We evaluated the correlation between leukocyte activity measured by two complementary methods. polymorphonuclear leukocyte (PMN)-elastase concentration and leukocyte scintigraphy. In 20 patients with CD, labeled leukocytes, 99m technetium hexamethyl propylene amine oxime (99mTc-HMPAO) scintigraphy, and PMN-elastase concentration were evaluated on the same day. A good correlation was found between PMN-elastase concentrations and the scintigraphic scores (p = 0.005; rs = 0.60; 95% CI, 0.20-0.83). Scintigraphy results were significantly correlated with CD activity index (p = 0.023, rs = 0.50). In four patients, scintigraphic scores and clinical disease activity were not consistent due to the state of PMN leukocyte activation, measured by elastase concentration. In CD, PMN-elastase can provide information about the degree of activation of PMN leukocytes and may explain discrepancy between clinical and scintigraphic indexes.

Switching of flagellar motility in Helicobacter pylori by reversible length variation of a short homopolymeric sequence repeat in fliP, a gene encoding a basal body protein

The genome of Helicobacter pylori contains numerous simple nucleotide repeats that have been proposed to have regulatory functions and to compensate for the conspicuous dearth of master regulatory pathways in this highly host-adapted bacterium. H. pylori strain 26695, whose genomic sequence was determined by The Institute for Genomic Research (TIGR), contains a repeat of nine cytidines in the fliP flagellar basal body gene that splits the open reading frame in two parts. In this work, we demonstrate that the 26695(C9) strain with a split fliP gene as sequenced by TIGR was nonflagellated and nonmotile. In contrast, earlier isolates of strain 26695 selected by positive motility testing as well as pig-passaged derivatives of 26695 were all flagellated and highly motile. All of these motile strains had a C(8) repeat and consequently a contiguous fliP reading frame. By screening approximately 50,000 colonies of 26695(C9) for motility in soft agar, a motile revertant with a C(8) repeat could be isolated, proving that the described switch is reversible. The fliP genes of 20 motile clinical H. pylori isolates from different geographic regions possessed intact fliP genes with repeats of eight cytidines or the sequence CCCCACCC in its place. Isogenic fliP mutants of a motile, C(8) repeat isolate of strain 26695 were constructed by allelic exchange mutagenesis and found to be defective in flagellum biogenesis. Mutants produced only small amounts of flagellins, while the transcription of flagellin genes appeared unchanged. These results strongly suggest a unique mechanism regulating motility in H. pylori which relies on slipped-strand mispairing-mediated mutagenesis of fliP.

Very late onset small intestinal B cell lymphoma associated with primary intestinal lymphangiectasia and diffuse cutaneous warts

As only a handful of lymphoma cases have been reported in conjunction with primary intestinal lymphangiectasia, it is not yet clear if this association is merely fortuitous or related to primary intestinal lymphangiectasia induced immune deficiency. We report on two female patients, 50 and 58 years old, who developed small intestinal high grade B cell lymphoma a long time (45 and 40 years, respectively) after the initial clinical manifestations of primary intestinal lymphangiectasia. They presented with a longstanding history of fluctuating protein losing enteropathy, multiple cutaneous plane warts, and markedly dilated mucosal and submucosal lymphatic channels in duodenal biopsies. One had a large ulcerated tumour of the proximal ileum and the other diffuse ileal infiltration. In both, histological examination showed centroblastic high grade B cell lymphoma associated with duodenojejuno-ileal mucosal and submucosal lymphangiectasia. They were subsequently successfully treated with surgery and postoperative chemotherapy (AVmCP: adriamycin, cyclophosphamide, Vm26, and prednisolone), and chemotherapy alone (PACOB: adriamycin, cyclophosphamide, vincristine, bleomycine, and prednisolone), respectively. A three year follow up in both cases showed persistent diffuse lymphangiectasia without evidence of lymphoma. The present findings support the hypothesis that primary intestinal lymphangiectasia is associated with lymphoma development.

Identification of the operon for the sorbitol (Glucitol) Phosphoenolpyruvate:Sugar phosphotransferase system in Streptococcus mutans

Transposon mutagenesis and marker rescue were used to isolate and identify an 8.5-kb contiguous region containing six open reading frames constituting the operon for the sorbitol P-enolpyruvate phosphotransferase transport system (PTS) of Streptococcus mutans LT11. The first gene, srlD, codes for sorbitol-6-phosphate dehydrogenase, followed downstream by srlR, coding for a transcriptional regulator; srlM, coding for a putative activator; and the srlA, srlE, and srlB genes, coding for the EIIC, EIIBC, and EIIA components of the sorbitol PTS, respectively. Among all sorbitol PTS operons characterized to date, the srlD gene is found after the genes coding for the EII components; thus, the location of the gene in S. mutans is unique. The SrlR protein is similar to several transcriptional regulators found in Bacillus spp. that contain PTS regulator domains (J. Stülke, M. Arnaud, G. Rapoport, and I. Martin-Verstraete, Mol. Microbiol. 28:865-874, 1998), and its gene overlaps the srlM gene by 1 bp. The arrangement of these two regulatory genes is unique, having not been reported for other bacteria.

[Mediastinoscopy in the case of recurrent uveitis]

INTRODUCTION

The authors report the case of a patient who presented for 4 years recurrent anterior uveitis accompanied by asymptomatic tuberculous mediastinal lymphadenitis.

EXEGESIS

CT scan of the chest showed the existence of mediastinal lymphadenopathy (< 1 cm). Mediastinoscopy with biopsy of the right laterotracheal lymph node was performed. The culture was positive for Mycobacterium tuberculosis, thus permitting the diagnosis of tuberculosis.

CONCLUSION

This case report stresses the advantage of extensive etiological assessment when faced with unexplained uveitis; particularly it emphasizes the importance of investigating potential tuberculosis. The existence of granulomatous uveitis, a positive skin test, the ethnic origin, and mostly results of chest CT scan, were the rationale for the use of mediastinoscopy with lymph node biopsy to help guide diagnosis.

[Hepatic ischemia and hypophyseal macroadenoma]

We report the first case of recurrent hepatitis secondary to a pituitary macroadenoma in a 55-year old man. Liver ischemia is thought to be the main consequence of episodes of acute adrenal insufficiency. Sudden acute adrenal insufficiency was due to enlargement of the sella content secondary to several microhemorrhages in the macroadenoma.

Is antiviral treatment (IFN alpha and/or ribavirin) justified in cirrhosis related to hepatitis C virus? Société Royale Belge de Gastro-entérologie

AIM

To assess the benefit risk ratio of interferon and ribavirin in the treatment of patients with post hepatitis C cirrhosis we summarize the spontaneous over mortality of this disease, and made an overview of the randomized trials and of other controlled studies.

RESULTS

In comparison to controls, patients with post hepatitis C cirrhosis have a 17 fold increase risk of dying from a liver disease that a control population, and a 6 fold increase from primary liver cancer. In France the hepatitis C epidemic which start in the sixties explains now the observed dramatic increase in mortality by primary liver cancer, both in men and women. Meta-analysis of randomized trials and controlled retrospective studies showed that interferon treatment is associated with a significant increase in ALT response at the end of the treatment, with a decrease in hepatocellular incidence as well as a decrease in mortality in comparison with controls. Very few data are published concerning ribavirin alone or in combination with interferon in patients with cirrhosis. Preliminary data suggest that this combination during 48 weeks permit to obtain in patients with compensated cirrhosis 20% of sustained virological response. The safety was acceptable but patients with low initial blood cells count must be carefully followed. In conclusion this overview clearly demonstrates a benefit-risk ratio in favor of treatment in patients with post hepatitis C cirrhosis by interferon.

[Turner syndrome and nodular regenerative hyperplasia of the liver]

Turner's syndrome is an ovarian dysgenesis (karyotype 45 X0) characterized by sexual infantilism and multiple malformations. Liver enzyme anomalies are often observed, but the underlying pathogenic mechanism remains unknown. Nodular regenerative hyperplasia of the liver is associated with another disease in about 80% of cases. However, these two diseases have only been reported together in one woman. We describe here a second case of this association "Turner's syndrome and nodular regenerative hyperplasia". We think that women with Turner's syndrome should benefit from screening for nodular regenerative hyperplasia by searching for elevated liver enzymes. This easily applicable screening protocol would provide early diagnostic of nodular regenerative hyperplasia and allow early and effective treatment of portal hypertension. Moreover, this approach would improve our knowledge of this association.

Acquired hemophilia secondary to factor VIII inhibitors after pregnancy

We report the case of a 26 year-old woman who developed acquired hemophilia secondary to factor VIII inhibitors, two months after a normal pregnancy. The initial hemorrhagic event was a spontaneous deep muscular hematoma mimicking a deep venous thrombosis. This observation was marqued by the apparition of antibodies against porcin factor VIII under treatment by porcin factor VIII. Intravenous immunoglobulin was ineffective, then cyclophosphamide was necessary to control the disease.

Acute hepatitis during hypersensitivity syndrome due to midecamycin

We report here the first case of symptomatic acute hepatic injury due to midecamycin in a 58-year-old man. The clinical picture was compatible with a hypersensitivity syndrome with cutaneous, renal and hepatic involvement. Liver eosinophil polynuclear infiltrate, hypereosinophilia and acute interstitial nephritis were consistent with the hypothesis of an immunoallergic mechanism.

Effects of cirrhosis, interferon and azathioprine on adverse events in patients with chronic hepatitis C treated with ribavirin

To determine adverse events of ribavirin in the treatment of chronic hepatitis C, 41 patients (18 with cirrhosis), treated with ribavirin at an initial dose of 600-1200mg day(-1), were analysed retrospectively (six patients were treated twice because adverse effects during the first treatment necessitated cessation of ribavirin). Indications for ribavirin included a contraindication (n = 15) an intolerance (n = 11) or a non-response (n = 15) to interferon (IFN). Ribavirin was combined with IFN 3 million units (MU) three times weekly for 15 patients and with azathioprine for six patients (five of whom were transplant patients). No cirrhotics and only one patient treated with ribavirin + IFN received azathioprine. The mean duration of treatment was 5 months (range 1-18 months). Sixteen of 47 treatments (34%) with ribavirin were stopped: four because of vomiting (8.5%), two for psychiatric disorder, one for dry cough, one for an unrelated cause, and eight (at 1-2 months) because of a fall in the level of haemoglobin (Hb) of 4.6 g dl(-1) (range 2.7-5.9 g dl[-1]); however, according to the rules of international protocol, we would have expected only four treatments (two in patients receiving azathioprine) with Hb < 8.5 g dl(-1) to be stopped. The decrease in Hb level occurred more slowly in patients treated with IFN plus ribavirin than in patients treated with ribavirin alone and was of lower clinical significance in patients with cirrhosis than in patients without cirrhosis. After exclusion of patients receiving azathioprine, there was no significant difference in the fall of Hb level between cirrhotic and non-cirrhotic patients and between patients treated with IFN plus ribavirin and patients treated with ribavirin alone. Interestingly, the platelet count of patients treated with IFN plus ribavirin fell less than in patients treated with IFN alone. The most important and expected adverse event associated with ribavirin was haemolysis. Anaemia < 8.5 g dl(-1), requiring cessation of ribavirin therapy, was present in 9% of patients and was worsened by azathioprine. Abdominal discomfort and dry cough were other, potentially important, clinical adverse events found in our study.

Meta-analysis of interferon randomized trials in the treatment of viral hepatitis C: effects of dose and duration

The aims of this study were to evaluate the benefits of higher doses or of longer duration in comparison with a standard interferon regimen (3 MU three times per week for 6 months) in chronic hepatitis C, and to assess the efficacy of interferon in acute hepatitis C. Meta-analysis made use of the Peto et al. and the Der Simonian and Laird methods, with heterogeneity and sensitivity analyses. In chronic hepatitis, a total of 17 trials versus controls and of 16 trials comparing different interferon regimens were included. Standard regimen, 3 MU three times per week for 6 months, was associated with an increase of the complete alanine transaminase (ALT) response rate and sustained (ALT) response rate by 45% (95% confidence interval: 35% to 55%; P < .001) and 21% (13% to 28%; P < .001), respectively, with the natural course being less than 2% of spontaneous responses. There was a significant dose effect (6 vs. 3 MU three times per week) upon the sustained response rate at 12 months, with a mean 17% increase (7% to 28%; P < .001), but not at 6 months. There was a significant duration effect (12 vs. 6 months) upon the sustained response rate both at the dose of 3 MU with a mean of 16% (9% to 23%; P < .001), and at the dose of 6 MU three times per week with a mean of 20% (7% to 33%; P = .003). In acute hepatitis C, 3 months of interferon treatment showed significant efficacy versus controls (4 trials), upon the complete ALT response (69% vs. 29%; P < .001), the sustained response rate during the 12 months following treatment (53% vs. 32%; P = .02), and hepatitis C virus (HCV)-RNA clearance (41% vs. 4%; P < .001). The best efficacy/risk ratio was in favor of 3 MU three times per week for at least 12 months in patients with chronic hepatitis C who had never been treated with interferon. Patients with acute hepatitis should be treated with at least 3 MU three times per week for 3 months.

Regulation of ATP-dependent P-(Ser)-HPr formation in Streptococcus mutans and Streptococcus salivarius

Sugar transport via the phosphoenolpyruvate (PEP) phosphotransferase system involves PEP-dependent phosphorylation of the general phosphotransferase system protein, HPr, at histidine 15. However, gram-positive bacteria can also carry out ATP-dependent phosphorylation of HPr at serine 46 by means of (Ser)HPr kinase. In this study, we demonstrate that (Ser)HPr kinase in crude preparations of Streptococcus mutans Ingbritt and Streptococcus salivarius ATCC 25975 is membrane associated, with pH optima of 7.0 and 7.5, respectively. The latter organism possessed 7- to 27-fold-higher activity than S. mutans NCTC 10449, GS-5, and Ingbritt strains. The enzyme in S. salivarius was activated by fructose-1,6-bisphosphate (FBP) twofold with 0.05 mM ATP, but this intermediate was slightly inhibitory with 1.0 mM ATP at FBP concentrations up to 10 mM. Similar inhibition was observed with the enzyme from S. mutans Ingbritt. A variety of other glycolytic intermediates had no effect on kinase activity under these conditions. The activity and regulation of (Ser)HPr kinase were assessed in vivo by monitoring P-(Ser)-HPr formation in steady-state cells of S. mutans Ingbritt grown in continuous culture with limiting glucose (10 and 50 mM) and with excess glucose (100 and 200 mM). All four forms of HPr [free HPr, P approximately (His)-HPr, P-(Ser)-HPr, and P approximately (His)-P-(Ser)-HPr] could be detected in the cells; however, significant differences in the intracellular levels of the forms were apparent during growth at different glucose concentrations. The total HPr pool increased with increasing concentrations of glucose in the medium, with significant increases in the P-(Ser)-HPr and P approximately HHis)-P-(Ser)-HPr concentrations. For example, while total PEP-dependent phosphorylation [P approximately(His)-HPr plus P approximately (His)-P-(Ser)-HPr] varied only from 21.5 to 52.5 microgram mg of cell protein (-1) in cells grown at the four glucose concentrations, the total ATP-dependent phosphorylation [P-(Ser)-HPr plus P approximately (His)-P-(Ser)-HPr] increased 12-fold from the 10 mM glucose-grown cells (9.1 microgram mg of cell protein (-1) to 106 and 105 microgram mg(-1) in the 100 and 200 mM glucose-grown cultures, respectively. (Ser)HPr kinase activity in membrane preparations of the cells varied little between the 10, 50, and 100 mM glucose-grown cells but increased threefold in the 200 mM glucose-grown cells. The intracellular levels of ATP, glucose-6-phosphate, and FBP increased with external glucose concentration, with the level of FBP being 3.8-fold higher for cells grown with 200 mM glucose than for those grown with 10 mM glucose. However, the variation in the intracellular levels of FBP, particularly between cells grown with 100 and 200 mM glucose, did not correlate with the extent of P-(Ser)-HPr formation, suggesting that the activity of (Ser)HPr kinase is not critically dependent on the availability of intracellular FBP.

Glucose transport by a mutant of Streptococcus mutans unable to accumulate sugars via the phosphoenolpyruvate phosphotransferase system

Streptococcus mutans transports glucose via the phosphoenolpyruvate (PEP)-dependent sugar phosphotransferase system (PTS). Earlier studies indicated that an alternate glucose transport system functions in this organism under conditions of high growth rates, low pH, or excess glucose. To identify this system, S. mutans BM71 was transformed with integration vector pDC-5 to generate a mutant, DC10, defective in the general PTS protein enzyme I (EI). This mutant expressed a defective EI that had been truncated by approximately 150 amino acids at the carboxyl terminus as revealed by Western blot (immunoblot) analysis with anti-EI antibody and Southern hybridizations with a fragment of the wild-type EI gene as a probe. Phosphotransfer assays utilizing 32P-PEP indicated that DC10 was incapable of phosphorylating HPr and EIIAMan, indicating a nonfunctional PTS. This was confirmed by the fact that DC10 was able to ferment glucose but not a variety of other PTS substrates and phosphorylated glucose with ATP and not PEP. Kinetic assays indicated that the non-PTS system exhibited an apparent Ks of 125 microM for glucose and a Vmax of 0.87 nmol mg (dry weight) of cells-1 min-1. Sugar competition experiments with DC10 indicated that the non-PTS transport system had high specificity for glucose since glucose transport was not significantly by a 100-fold molar excess of several competing sugar substrates, including 2-deoxyglucose and alpha-methylglucoside. These results demonstrate that S. mutans possesses a glucose transport system that can function independently of the PEP PTS.