Citrobacter rodentium Induces Tissue-Resident Memory CD4+ T Cells.

Tissue-resident memory T cells (TRM cells) are a novel population of tissue-restricted antigen-specific T cells. TRM cells are induced by pathogens and promote host defense against secondary infections. Although TRM cells cannot be detected in circulation, they are the major memory CD4+ and CD8+ T-cell population in tissues in mice and humans. Murine models of CD8+ TRM cells have shown that CD8+ TRM cells maintain tissue residency via CD69 and though tumor growth factor ß-dependent induction of CD103. In contrast to CD8+ TRM cells, there are few models of CD4+ TRM cells. Thus, much less is known about the factors regulating the induction, maintenance, and host defense functions of CD4+ TRM cells. Citrobacter rodentium is known to induce IL-17+ and IL-22+ CD4+ T cells (Th17 and Th22 cells, respectively). Moreover, data from IL-22 reporter mice show that most IL-22+ cells in the colon 3 months after C. rodentium infection are CD4+ T cells. This collectively suggests that C. rodentium may induce CD4+ TRM cells. Here, we demonstrate that C. rodentium induces a population of IL-17A+ CD4+ T cells that are tissue restricted and antigen specific, thus meeting the criteria of CD4+ TRM cells. These cells expand and are a major source of IL-22 during secondary C. rodentium infection, even before the T-cell phase of the host response in primary infection. Finally, using FTY 720, which depletes circulating naive and effector T cells but not tissue-restricted T cells, we show that these CD4+ TRM cells can promote host defense.

Occult hepatitis B virus infection in HIV-infected Lebanese patients with isolated antibodies to hepatitis B core antigen.

The presence of hepatitis B virus (HBV) serological markers have been investigated in 101 Lebanese patients (69 men, 32 women; mean age 32.7 +/- 1.7 years) infected with human immunodeficiency virus type 1 (HIV-1). Seven patients (6.9%) were HBsAg carriers compared with 54 patients (53.5%) who had no evidence of exposure to HBV infection. Twenty-four patients (23.8%) had anti-HBc alone as a serological marker compared with four patients who were positive for anti-HBs alone and 12 patients (11.9%) who were anti-HBc and anti-HBs-positive. Occult HBV infection (presence of HBV DNA in the absence of HBsAg) is found to be relatively high (28.7%) in HIV-infected Lebanese patients and the overwhelming majority (83.3%) of those who were positive for anti-HBc alone had a detectable HBV DNA in their serum. However, none of our HIV-positive patients with occult HBV infection had abnormal alanine aminotransferase level, which also raises the question as to whether occult HBV plays a role in the aetiology of liver disease in HIV-infected patients. Further, studies on the association between HBV DNA levels and markers of liver function in addition to data on liver biopsy would help in answering this question.

Occult hepatitis B virus infection in Lebanese patients with chronic hepatitis C liver disease.

Occult hepatitis B virus (HBV) infection, characterised by the presence of HBV infection with undetectable hepatitis B surface antigen (HBsAg), was investigated in 98 Lebanese patients with chronic hepatitis C liver disease and 85 control subjects recruited from eight institutions in different parts of the country. The prevalence of occult HBV infection ranged from 11.9% to 44.4% in hepatitis C virus (HCV)-infected patients and it increased with increasing severity of the liver disease. The overall rate of HBV DNA in our 98 HCV-infected patients was 16.3%. On the other hand, the rate of HBV DNA was 41.0% in anti-HBc alone positive patients compared to only 7.1% in healthy controls who were also anti-HBc alone positive (p < 0.001). Moreover, the prevalence HBV DNA increased with increasing severity of the liver disease, but this increase was only marginally significant and, perhaps, could have been significant if more patients were involved in the study. Although Lebanon is an area of low endemicity for both HBV and HCV, occult HBV infection is common in HCV-infected patients. The presence of HBV DNA, therefore, presents a challenge for the effective laboratory diagnosis of hepatitis B, particularly if polymerase chain reaction (PCR)-based HBV detection methods are not used.

Hepatitis B virus DNA in serum of 'anti-HBc only'-positive healthy Lebanese blood donors: significance and possible implications.

Transmission of HBV infection through transfusion of HBsAg-negative blood has been documented. It is evident that low levels of HBV-DNA remain detectable in serum and liver tissue of some patients who clear HbsAg, and that the detection rate is highest in individuals who are 'anti-HBc positive alone'. This study was designed to assess the frequency and clinical significance of 'anti-HBc alone' in Lebanese blood donors. A total of 5511 blood donor samples from three major hospitals representing most regions of the country were tested for anti-HBc, amongst other screening tests. Samples positive for 'anti-HBc alone' were then tested for HBV-DNA and any positive for HBV-DNA were then genotyped and investigated for hepatitis B viral load. The study showed that 203 (3.7%) of randomly selected Lebanese blood donors were confirmed as 'anti-HBc alone'. Of these, 11 (5.4%) were HBV-DNA positive as detected by nested PCR. All samples had HBV-DNA levels below 400 copies/ml and all were genotype D. It can be concluded that HBV was present, although the circulating amount of virus was below the detectable limit for the assay used. Therefore, routine screening for anti-HBc may be required in Lebanese blood donation centres as an additional preventive measure for controlling transmission of HBV via blood transfusion.

De-regulation of the sonic hedgehog pathway in the InsGas mouse model of gastric carcinogenesis.

This study investigated sonic hedgehog (Shh) signalling in gastric metaplasia in the insulin-gastrin (InsGas) hypergastrinaemic mouse +/- Helicobacter felis (H. felis) infection. Sonic hedgehog gene and protein expression was reduced in pre-metaplastic lesions from non-infected mice (90% gene reduction, P<0.01) compared to normal mucosa. Sonic hedgehog was reactivated in gastric metaplasia of H. felis-infected mice (3.5-fold increase, P<0.01) compared to pre-metaplastic lesions. Additionally, the Shh target gene, glioma-associated oncogene (Gli)-1, was significantly reduced in the gastric glands of InsGas mice (75% reduction, P<0.05) and reactivated with H. felis infection (P<0.05, base of glands, P<0.01 stroma of metaplastic glands). The ability of H. felis to activate the Shh pathway was investigated by measuring the effect of target cytokine, interleukin-8 (IL-8), on Shh expression in AGS and MGLVA1 cells, which was shown to induce Shh expression at physiological concentrations. H. felis induced the expression of NF-kappaB in inflammatory infiltrates in vivo, and the expression of the IL-8 mouse homologue, protein KC, in inflammatory infiltrates and metaplastic lesions. Sonic hedgehog pathway reactivation was paralleled with an increase in proliferation of metaplastic lesions (15.75 vs 4.39% in infected vs non-infected mice, respectively, P<0.001). Furthermore, Shh overexpression increased the growth rate of the gastric cancer cell line, AGS. The antiapoptotic protein, bcl-2, was expressed in the stroma of infected mice, along with a second Shh target gene, patched-1 (P=0.0001, stroma of metaplastic gland). This study provides evidence suggesting reactivation of Shh signalling from pre-metaplastic to advanced metaplastic lesions of the stomach and outlines the importance of the Shh pathway as a potential chemoprophylactic target for gastric carcinogenesis.

Current prevalence of hepatitis delta virus (HDV) infection and the range of HDV genotypes in Lebanon.

Recently the prevalence of hepatitis B virus (HBV) genotypes and the association between these genotypes and the clinical status of HBV-infected patients were recently investigated in the Lebanese population. The aim of the additional study reported here was to determine the current prevalence of hepatitis delta virus (HDV) infection and the range of HDV genotypes in this Lebanese population. Two hundred and fifty-eight HBsAg-positive patients (107 asymptomatic blood donors, 92 with chronic hepatitis, 24 with cirrhosis, 15 with hepatocellular carcinoma, 20 patients on haemodialysis) from ten medical centers in Lebanon were tested for antibody to hepatitis D virus (anti-HDV). Those testing positive were analysed further for HDV-RNA and for genotyping by reverse transcriptase-polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP). Three samples (1.2%) were anti-HDV positive and out of these, only one was HDV-RNA positive (0.6%) and was analysed as HDV genotype I. Our results point to a low endemicity of HDV in the Lebanese population which is in sharp contrast to data reported from Lebanon 20 years ago and to the situation in neighbouring Arab and non-Arab countries in the Mediterranean region. HDV genotype I seems to be the predominant genotype in Lebanon and the Middle East.

Prevalence of the genes encoding extended-spectrum beta-lactamases, in Escherichia coli resistant to beta-lactam and non-beta-lactam antibiotics.

The prevalences of extended-spectrum beta-lactamases (ESBL) and their encoding bla genes, TEM, SHV and CTX_M, were investigated in isolates of Escherichia coli that were resistant to beta-lactam and/or non-beta-lactam antibiotics. Of the 250 E. coli isolates investigated, all of which came from patients in a major hospital in southern Lebanon, 61 (13.3%) were found to have ESBL, their production of beta-lactamase being confirmed by the ceftazidime and ceftazidime/clavulanic-acid disc methods. All 61 ESBL isolates were resistant to beta-lactams and sensitive to imipenem, piperacillin/tazobactam and cefoxitime. Only 40% were resistant to fluoroquinolones, 33% were resistant to aminoglycosides, and 18% were considered to have multi-drug resistance. The results of the PCR-based amplification of the bla gene in DNA samples from the 61 ESBL isolates indicated that 11 (18%) of the isolates carried both the TEM and SHV genes, 37 (61%) carried the TEM gene but not the SHV, and 13 (21%) had the SHV gene but not the TEM. None of the isolates carried the CTX_M gene. Of the 37 TEM-positive/SHV-negative isolates, 43% were resistant to fluoroquinolones and 37% to aminoglycosides. Increased resistance to non-beta-lactam antibiotics was observed in the isolates harbouring both the TEM and SHV genes, of which 54% were resistant to all of the tested antibiotics except imipenem, 36% were only resistant to fluoroquinolones, and 9.1% only resistant to aminoglycosides. The possibility that the concomitant presence of TEM- and SHV-type beta-lactamases is associated with resistance to non-beta-lactam antibiotics requires further research. The prevalences of ESBL and their encoding genes in Gram-negative bacteria collected from various regions in Lebanon will now be investigated.

Successful treatment of Candida albicans osteomyelitis of the spine with fluconazole and surgical debridement: case report.

A 65-year old diabetic male presented with progressive bone destruction of thoracic spine (T-11&12) with cord compression. Candida albicans was isolated from aspirated materials pre-and intra-operative. Two weeks of fluconazole was given prior to surgical debridement, and fixation of the lesion. C. albicans isolated pre-and 2-weeks after fluconazole treatment were DNA-typed using AP-PCR. MIC was 2-4 mg/l in all isolates tested. The pre-and post treatment isolates had two DNA patterns, indicating the existence of two different strains. Surgical treatment was necessary for patient recovery.

Incidence of the prozone phenomenon in syphilis serology.

OBJECTIVE: To determine the rate of the prozone phenomenon in our patient population. METHODS: Sera from 4328 patients--3504 females (2065 pregnant, 1439 nonpregnant) and 824 males--were tested for syphilis by the rapid plasma reagin (RPR) test, and then rechecked with serial twofold dilutions of up to 16-fold to detect the prozone phenomenon. Chi-square analysis with Yates correction was used, with P < or = .05 considered significant. RESULTS: The total positivity rate in females was 6% (213 patients); 13% (27) of the positive tests were false-positive reactions as confirmed by a negative anti-treponemal antibody test. Only one prozone reaction was detected, in serum from a male subject, but it was not missed on initial screening. CONCLUSION: The rate of prozone phenomenon is very low (95% confidence interval 0-0.4%), and routine serial dilutions are not cost effective.

False-negative syphilis screening due to change in temperature.

BACKGROUND AND OBJECTIVES: Inaccurate test results for syphilis may cause an individual to experience serious effects. GOAL OF THE STUDY: Investigate potential sources of error and test limitations causing false-negative reactions. STUDY DESIGN: In 5 months, two laboratories screened 2,232 patients for syphilis by the Rapid Plasma Reagin (RPR) test. RESULTS: The hospital laboratory reported 5.3% (64/1,210) of patients' test as reactive on initial screening, and the research laboratory found 6.4% (78/1,210) reactive. Fourteen reactive patients were incorrectly reported negative by the hospital laboratory, as confirmed by both laboratories. A refrigerated centrifuge in the hospital laboratory possibly caused sera to be cooled before testing, producing false-negative results. When its temperature was adjusted from 4 degrees C to 27 degrees C, an additional 1,022 samples tested were consistent between the two laboratories. CONCLUSION: Cold temperature produces false-negative reactions for syphilis screenings in patients' samples with titers < 1:4 dilution. Patients' samples with titers > or = 1:16 dilution were not affected. According to this study, incorrect temperatures for test sera can alter testing outcomes. Therefore, test manufacturer's directions must be strictly followed.

Evaluation of the Baxter-MicroScan 4-hour enzyme-based yeast identification system.

A new 4-h Yeast Identification Panel (YIP; Baxter-MicroScan, W. Sacramento, Calif.) was compared with the API 20C Yeast Identification System (Analytab Products, Inc., Plainview, N.Y.) in the identification of recent clinical yeast isolates. The YIP had a 94% correlation (288 of 306) in identifying 22 species within the genera Candida, Hansenula, Pichia, Rhodotorula, Saccharomyces, and Torulopsis. Correlation dropped to 65% for those species within the genera of slower growing yeasts, i.e., Blastoschizomyces spp., Crpytococcus spp., Geotrichum spp., Hyphopichia spp., Phaeococcomyces spp., Prototheca spp., and Trichosporon spp. Overall correlation with the API 20C was 92% (365 of 401) for those taxa included in the data base and 85% (373 of 437) for all yeasts encountered in the study. There were 36 (8.2%) discrepant identifications, which were due in part to the limited data base. Expansion of the data base plus the easy inoculation, reading, and rapid results of the YIP should make it an excellent method for yeast identification.

Disseminated Conidiobolus infection with endocarditis in a cocaine abuser.

A crack cocaine abuser developed disseminated infection caused by a species of Conidiobolus not known to cause disease in vertebrates. The fungus gained entry via skin abrasions on the lower extremities, spread through the hematogenous route, and caused endocarditis. There was evidence of fungal infection in the lungs, heart, kidneys, skeletal muscles, and brain. An additional complication was extensive rhabdomyolysis, with a marked elevation of creatine kinase of up to 1.2 million U/L.

Evaluation of the updated Vitek yeast identification data base.

Using 398 isolates of yeasts and yeastlike fungi comprising 9 genera and 26 species, as well as the hyphomycete Geotrichum candidum and the achlorophyllous alga Prototheca wickerhamii, we compared the API 20C yeast identification system with the modified Vitek yeast identification system with an expanded data base. We found 11 discrepancies between the two systems: five (1.3%) of the isolates (Blastoschizomyces capitatus, 1; Candida albicans, 1; Hansenula anomala, 1; Rhodotorula minuta, 2) had biocodes not included in the expanded Vitek data base, and six (1.5%) of the isolates (Candida lusitaniae, 1; Candida parapsilosis, 1; Cryptococcus uniguttulatus, 1; H. anomala, 1; Torulopsis candida, 2) were misidentified by the Vitek system. Overall, the efficacy of the Vitek system compares favorably with that of the API 20C in the identification of clinically important yeasts.