Attaching and effacing (A/E) pathogens are a significant cause of gastrointestinal illness in humans and animals. All A/E pathogens carry a large pathogenicity island, termed the locus for enterocyte effacement (LEE), which encodes a type III secretion system that translocates several effector proteins into host cells. To identify novel virulence determinants in A/E pathogens, we performed a signature-tagged mutagenesis screen in C57BL/6 mice by using the mouse A/E pathogen Citrobacter rodentium. Five hundred seventy-six derivatives of C. rodentium were tested in pools of 12 mutants. One attenuated mutant carried a transposon insertion in nleB, which encodes a putative effector of the LEE-encoded type III secretion system (T3SS). nleB is present in a genomic pathogenicity island that also encodes another putative effector, NleE, immediately downstream. Using translational fusions with ␤-lactamase (TEM-1), we showed that both NleB and NleE were translocated into host cells by the LEE-encoded T3SS of enteropathogenic Escherichia coli. In addition, deletion of the gene encoding NleB in C. rodentium resulted in reduced colonization of mice in single infections and reduced colonic hyperplasia. In contrast, the deletion of other non-LEE-encoded effector genes in C. rodentium, nleC, nleD, or nleE, had no effect on host colonization or disease. These results suggest that nleB encodes an important virulence determinant of A/E pathogens.

Candida spp. are responsible for most of the fungal infections in humans. Available since 1990, fluconazole is well established as a leading drug in the setting of prevention and treatment of mucosal and invasive candidiasis. Fluconazole displays predictable pharmacokinetics and an excellent tolerance profile in all groups, including the elderly and children. Fluconazole is a fungistatic drug against yeasts and lacks activity against moulds. Candida krusei is intrinsically resistant to fluconazole, and other species, notably Candida glabrata, often manifest reduced susceptibility. Emergence of azole-resistant strains as well as discovery of new antifungal drugs (new triazoles and echinocandins) have raised important questions about its use as a first line drug. The aim of this review is to summarize the main available data on the position of fluconazole in the prophylaxis or curative treatment of invasive Candida spp. infections. Fluconazole is still a major drug for antifungal prophylaxis in the setting of transplantation (solid organ and bone marrow), intensive care unit, and in neutropenic patients. Prophylactic fluconazole still has a place in HIV-positive patients in viro-immunological failure with recurrent mucosal candidiasis. Fluconazole can be used in adult neutropenic patients with systemic candidiasis, as long as the species identified is a priori susceptible. Among non-neutropenic patients with candidaemia fluconazole is one of the first line drugs for susceptible species. Cases reports and uncontrolled studies have also reported its efficacy in the setting of osteoarthritis, endophthalmitis, meningitis, endocarditis and peritonitis caused by Candida spp. among immunocompetent adults. In paediatrics, fluconazole is a well tolerated and major prophylactic drug for high-risk neonates, as well as an alternative treatment for neonatal candidiasis. Importantly 15 years after its introduction in the antifungal armamentarium, fluconazole is still a first line treatment option in several cases of invasive candidiasis. Its prophylactic use should however be limited to selected high-risk patients to limit the risk of emergence of azole-resistant strains.

BACKGROUND Proton pump inhibitors (PPIs) have been linked to acute kidney injury (AKI) and chronic kidney disease (CKD); however, current evidence has only been evaluated in a small number of studies with short follow-up periods. This study examined the association between PPI use and risk of incident AKI and CKD in a large population-based health maintenance organization (HMO) cohort. METHODS Patients aged 18 years or older, without evidence of preexisting renal disease, started on PPI therapy, and those continuously enrolled for at least 12 months between July 1993 and September 2008 were identified in an HMO database. Incidences of AKI and CKD were defined using documented International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes or a glomerular filtration rate less than 60 ml/min/1.73 m 2 after initiation of PPI therapy. Patients with AKI were followed for up to 90 days (cohort 1), and patients with CKD required at least 1 year of follow-up (cohort 2). Multivariable logistic regression analyses were used to adjust for differences in demographics (excluding race), comorbidities, and medication use between groups. RESULTS In 93,335 patients in the AKI cohort, 16,593 of whom were exposed to PPIs, the incidence rate of AKI was higher in the PPI group than nonusers (36.4 vs 3.54 per 1000 person-years, p<0.0001, respectively). In adjusted models, PPI exposure was associated with an increased risk of AKI (adjusted odds ratio [aOR] 4.35, 95% confidence interval [CI] 3.14-6.04, p<0.0001). In 84,600 patients in the CKD cohort, 14,514 of whom were exposed to PPIs, the incidence rate of CKD was higher in the PPI group than nonusers (34.3 vs 8.75 per 1000 person-years, p<0.0001, respectively). In adjusted models, PPIs were associated with a higher risk of CKD compared with controls (aOR 1.20, 95% CI 1.12-1.28, p<0.0001). Associations between PPI use and AKI and CKD persisted in propensity score-matched analyses. CONCLUSION The use of PPIs is associated with an increased risk of incident AKI and CKD. This relationship could have a considerable public health impact; therefore, health care provider education and deprescribing initiatives will be necessary to raise awareness and reduce health care burden. KEY WORDS acute kidney injury, chronic kidney disease, observational study, proton pump inhibitors.

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Citrobacter rodentium is an attaching and effacing pathogen which causes transmissible colonic hyperplasia in mice. Infection with C. rodentium serves as a model for infection of humans with enteropathogenic and enterohemorrhagic Escherichia coli. To identify novel colonization factors of C. rodentium, we screened a signature-tagged mutant library of C. rodentium in mice. One noncolonizing mutant had a single transposon insertion in an open reading frame (ORF) which we designated regA because of its homology to genes encoding members of the AraC family of transcriptional regulators. Deletion of regA in C. rodentium resulted in markedly reduced colonization of the mouse intestine. Examination of lacZ transcriptional fusions using promoter regions of known and putative virulence-associated genes of C. rodentium revealed that RegA strongly stimulated transcription of two newly identified genes located close to regA, which we designated adcA and kfcC. The cloned adcA gene conferred autoaggregation and adherence to mammalian cells to E. coli strain DH5␣, and a kfc mutation led to a reduction in the duration of intestinal colonization, but the kfc mutant was far less attenuated than the regA mutant. These results indicated that other genes of C. rodentium whose expression required activation by RegA were required for colonization. Microarray analysis revealed a number of RegAregulated ORFs encoding proteins homologous to known colonization factors. Transcription of these putative virulence determinants was activated by RegA only in the presence of sodium bicarbonate. Taken together, these results show that RegA is a global regulator of virulence in C. rodentium which activates factors that are required for intestinal colonization.