High prevalence of CTX-M-1 group in ESBL-producing enterobacteriaceae infection in intensive care units in southern Chile

ABSTRACT Enterobacteria-producing extended-spectrum β-lactamases (ESBL) play an important role in healthcare infections, increasing hospitalization time, morbidity and mortality rates. Among several ESBLs that emerge from these pathogens, CTX-M-type enzymes had the most successful global spread in different epidemiological settings. Latin America presents high prevalence of CTX-M-2 in ESBL-producing enterobacterial infections with local emergence of the CTX-M-1 group. However, this high prevalence of the CTX-M-1 group has not yet been reported in Chile. The aim of this study was to identify ESBLs among enterobacteria isolated from clinical samples of critically ill patients from southern Chile. One-hundred thirty seven ESBL-producing bacteria were isolated from outpatients from all critical patient units from Hernán Henríquez Aravena Hospital. Phenotype characterization was performed by antibiogram, screening of ESBL, and determination of minimum inhibitory concentration (MIC). PCR was used for genetic confirmation of resistance. Molecular typing was performed by ERIC-PCR. ESBL-producing isolates were identified as Klebsiella pneumoniae (n = 115), Escherichia coli (n = 18), Proteus mirabilis (n = 3), and Enterobacter cloacae (n = 1), presenting multidrug resistance profiles. PCR amplification showed that the strains were positive for blaSHV (n = 111/81%), blaCTX-M-1 (n = 116/84.7%), blaTEM (n = 100/73%), blaCTX-M-2 (n = 28/20.4%), blaCTX-M-9 (0.7%), blaPER-1 (0.7%), and blaGES-10 (0.7%). The multiple production of ESBL was observed in 93% of isolates, suggesting high genetic mobility independent of the clonal relationship. The high frequency of the CTX-M-1 group and a high rate of ESBL co-production are changing the epidemiology of the ESBL profile in Chilean intensive care units. This epidemiology is a constant and increasing challenge, not only in Chile, but worldwide.

Clinical epidemiology, risk factors and treatment outcomes of extended-spectrum beta-lactamase producing Enterobacteriaceae bacteremia among children in a Tertiary Care Hospital, Bangkok, Thailand.

OBJECTIVE: Extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae infection is an emerging problem in paediatric populations leading to increased mortality. The purpose of this study was to determine the prevalence, risk factors and clinical outcomes of ESBL-producing Enterobacteriaceae in paediatric blood stream infections (BSIs). A retrospective review of paediatric patients diagnosed with Enterobacteriaceae bacteremia was performed at Phramongkutklao Hospital from 2010 to 2017. RESULTS: Among 97 non-duplicated blood isolates, the prevalence of ESBL-producing Enterobacteriaceae was 53.6% (28.9% Escherichia coli and 25.8% Klebsiella spp. isolates). The study indicated that the prevalence of ESBL infection was higher among patients with chronic illness, especially hematologic malignancies, than among patients without underlying disease (P = 0.01). No differences were observed in the prior use of any antibiotics, the use of extended-spectrum cephalosporin, neutropaenia or the presence of an indwelling central venous catheter. Mortality in the ESBL group was significantly higher than that in the non-ESBL group, with observed mortalities of 38.9% and 13.3%, respectively (P < 0.05). In conclusion, BSIs with ESBL-producing Enterobacteriaceae tended to increase infection rates and impact survival rates among paediatric patients.

Edwardsiella piscicida Type III Secretion System Effector EseK Inhibits Mitogen-Activated Protein Kinase Phosphorylation and Promotes Bacterial Colonization in Zebrafish Larvae.

Bacteria utilize type III secretion systems (T3SS) to deliver effectors directly into host cells. Hence, it is very important to identify the functions of bacterial (T3SS) effectors to understand host-pathogen interactions. Edwardsiella piscicida encodes a functional T3SS effector, EseK, which can be translocated into host cells and affect bacterial loads. Here, it was demonstrated that an eseK mutant (the ΔeseK mutant) significantly increased the phosphorylation levels of p38α, c-Jun NH2-terminal kinases (JNK), and extracellular signal-regulated protein kinases 1/2 (ERK1/2) in HeLa cells. Overexpression of EseK directly inhibited mitogen-activated protein kinase (MAPK) signaling pathways in HEK293T cells. The ΔeseK mutant consistently promoted the phosphorylation of MAPKs in zebrafish larva infection models. Further, it was shown that the ΔeseK mutant increased the expression of tumor necrosis factor alpha (TNF-α) in an MAPK-dependent manner. Importantly, the EseK-mediated inhibition of MAPKs in vivo attenuated bacterial clearance in larvae. Taken together, this work reveals that the E. piscicida T3SS effector EseK promotes bacterial infection by inhibiting MAPK activation, which provides insights into the molecular pathogenesis of E. piscicida in fish.

Citrobacter rodentium NleB Protein Inhibits Tumor Necrosis Factor (TNF) Receptor-associated Factor 3 (TRAF3) Ubiquitination to Reduce Host Type I Interferon Production.

Interferon signaling plays important roles in both intestinal homeostasis and in the host response to pathogen infection. The extent to which bacterial pathogens inhibit this host pathway is an understudied area of investigation. We characterized Citrobacter rodentium strains bearing deletions in individual type III secretion system effector genes to determine whether this pathogen inhibits the host type I IFN response and which effector is responsible. The NleB effector limited host IFN-ß production by inhibiting Lys(63)-linked ubiquitination of TNF receptor-associated factor 3 (TRAF3). Inhibition was dependent on the glycosyltransferase activity of NleB. GAPDH, a target of NleB during infection, bound to TRAF3 and was required for maximal TRAF3 ubiquitination. NleB glycosyltransferase activity inhibited GAPDH-TRAF3 binding, resulting in reduced TRAF3 ubiquitination. Collectively, our data reveal important interplay between GAPDH and TRAF3 and suggest a mechanism by which the NleB effector inhibits type I IFN signaling.

Defensive Mutualism Rescues NADPH Oxidase Inactivation in Gut Infection.

NOX/DUOX family of NADPH oxidases are expressed in diverse tissues and are the primary enzymes for the generation of reactive oxygen species (ROS). The intestinal epithelium expresses NOX1, NOX4, and DUOX2, whose functions are not well understood. To address this, we generated mice with complete or epithelium-restricted deficiency in the obligatory NOX dimerization partner Cyba (p22(phox)). We discovered that NOX1 regulates DUOX2 expression in the intestinal epithelium, which magnified the epithelial ROS-deficiency. Unexpectedly, epithelial deficiency of Cyba resulted in protection from C. rodentium and L. monocytogenes infection. Microbiota analysis linked epithelial Cyba deficiency to an enrichment of H2O2-producing bacterial strains in the gut. In particular, elevated levels of lactobacilli physically displaced and attenuated C. rodentium virulence by H2O2-mediated suppression of the virulence-associated LEE pathogenicity island. This transmissible compensatory adaptation relied on environmental factors, an important consideration for prevention and therapy of enteric disease.

Two carboxypeptidase counterparts from rock bream (Oplegnathus fasciatus): molecular characterization, genomic arrangement and immune responses upon pathogenic stresses.

Carboxypeptidases (CPs) are proteases that hydrolyze C-terminal peptide bonds. They are involved in regulating the complement system of the immune system. Here, we report the molecular characterization and immune response of two carboxypeptidases, named carboxypeptidase A (Rb-CPA) and carboxypeptidase N1 (Rb-CPN1), from rock bream. The genomic sequence of Rb-CPA contains 12 exons interrupted by 11 introns, while the genomic sequence of Rb-CPN1 has 9 exons and 8 introns. The cDNA sequence of Rb-CPA encodes a 421-amino-acid (AA) polypeptide (48kDa), and the cDNA of Rb-CPN1 encodes a 448-AA polypeptide (51kDa). The amino acid sequences of Rb-CPA and Rb-CPN1 were found to harbor two characteristic Zn-binding signature domains and a peptidase-M14 Zn carboxypeptidase site. Pairwise analysis revealed that Rb-CPA and Rb-CPN1 had the highest identity with the corresponding proteins from Anoplopoma fimbria (87.6%) and Dicentrarchus labrax (96.9%), respectively. qPCR results indicated that Rb-CPA and Rb-CPN1 were constitutively expressed mainly in the kidney, heart, liver, and head kidney. Both genes were transcriptionally regulated in the liver upon challenge with pathogenic bacteria (Streptococcus iniae, Edwardsiella tarda), rock bream iridovirus (RBIV), and the immune modulators polyinosinic:polycytidylic acid and lipopolysaccharide. Taken together, our findings suggest that Rb-CPA and Rb-CPN1 have immune-related functions in rock bream.

Nosocomial infections by Klebsiella pneumoniae carbapenemase producing enterobacteria in a teaching hospital / Infecções hospitalares por enterobactérias produtoras de Klebsiella pneumoniae carbapenemase em um hospital escola

Objective To analyze the profile of patients with microorganisms resistant to carbapenems, and the prevalence of the enzyme Klebsiella pneumoniae carbapenemase in interobacteriaceae. Methods Retrospective descriptive study. From the isolation in bacteriological tests ordered by clinicians, we described the clinical and epidemiological characteristics of patients with enterobacteria resistants to carbapenems at a university hospital, between March and October 2013. Results We included 47 isolated patients in this study, all exhibiting resistance to carbapenems, including 9 patients who were confirmed as infected/colonized with K. pneumoniae carbapenemase. Isolation in tracheal aspirates (12; 25.5%) predominated. The resistance to ertapenem, meropenem, and imipenem was 91.5%, 83.0% and 80.0%, respectively. Aminoglycosides was the class of antimicrobials that showed the highest sensitivity, 91.5% being sensitive to amikacin and 57.4% to gentamicin. Conclusion The K. pneumoniae carbapenemase was an important agent in graun isotaling in hospital intection. The limited therapeutic options emphasize the need for rapid laboratory detection, as well as the implementation of measures to prevent and control the spread of these pathogens. .

Objetivo Analisar o perfil dos pacientes que apresentaram microrganismos com resistência aos carbapenêmicos, e a prevalência da enzima Klebsiella pneumoniae carbapenemase em enterobactérias. Métodos Estudo retrospectivo descritivo. A partir do isolamento em exames bacteriológicos solicitados pelos clínicos, descrevemos as características clínicas e epidemiológicas dos pacientes que apresentaram enterobactérias resistentes aos carbapenêmicos entre março e outubro de 2013 em um hospital universitário. Resultados Foram incluídos 47 pacientes isolados, todos apresentando resistência aos carbapenêmicos, dos quais 9 tiveram confirmação de infecção/colonização por K. pneumoniae carbapenemase. Ocorreu predomínio de isolamento em aspirados traqueais (12; 25,5%). A resistência ao ertapenem, meropenem e imipenem foi de 91,5%, 83,0% e 80,0%, respectivamente. Os aminoglicosídeos foram a classe de antimicrobianos que apresentou maior sensibilidade, sendo 91,5% sensível a amicacina e 57,4% a gentamicina. Conclusão A K. pneumoniae carbapenemase constituiu um importante patógeno hospitalar em isolamento crescente nesse nosocômio. As limitadas opções terapêuticas reforçam a necessidade de uma rápida detecção laboratorial, assim como a implementação de medidas de prevenção e controle da disseminação desses patógenos. .

Activation of p38α in T cells regulates the intestinal host defense against attaching and effacing bacterial infections.

Intestinal infections by attaching and effacing (A/E) bacterial pathogens cause severe colitis and bloody diarrhea. Although p38α in intestinal epithelial cells (IEC) plays an important role in promoting protection against A/E bacteria by regulating T cell recruitment, its impact on immune responses remains unclear. In this study, we show that activation of p38α in T cells is critical for the clearance of the A/E pathogen Citrobacter rodentium. Mice deficient of p38α in T cells, but not in macrophages or dendritic cells, were impaired in clearing C. rodentium. Expression of inflammatory cytokines such as IFN-γ by p38α-deficient T cells was reduced, which further reduced the expression of inflammatory cytokines, chemokines, and antimicrobial peptide by IECs and led to reduced infiltration of T cells into the infected colon. Administration of IFN-γ activated the mucosal immunity to C. rodentium infection by increasing the expression of inflammation genes and the recruitment of T cells to the site of infection. Thus, p38α contributes to host defense against A/E pathogen infection by regulating the expression of inflammatory cytokines that activate host defense pathways in IECs.

Edwardsiella tarda invasion of fish cell lines and the activation of divergent cell death pathways.

Edwardsiella tarda is an important gram-negative intracellular pathogen of fish. However, the invasive features of E. tarda to fish cells and the pathogenesis of host cell death have not been thoroughly investigated. In this study, two fish cell models were used to investigate the interactions between E. tarda and its cellular hosts. E. tarda invaded and replicated in both cell lines. Epithelioma papulosum cyprini (EPC) cells were more sensitive to E. tarda infection than the flounder gill cell line FG-9307, with higher levels of intracellular bacteria in the former. The invasion and intracellular replication of E. tarda in FG-9307 cells were studied at the ultrastructural level, and infected cells with large amounts of replicated bacteria and destroyed organelles were observed. Apoptosis was observed in EPC cells upon infection, characterized by the occurrence of apoptotic bodies, DNA ladder, increased Annexin V binding and the activation of caspase-3, whereas E. tarda infected FG-9307 cells were negative for all of those features. E. tarda infection in FG-9307 cells failed to protect the staurosporine-induced apoptosis. Moreover, both intrinsic and extrinsic pathways were activated in EPC cells upon E. tarda infection. The present study revealed that E. tarda interacts with fish cells in different manners, and divergent pathways were activated in these cellular hosts to mediate cell death. These results provided new information on the interactions between E. tarda and fish cells.

Molecular responses of ceruloplasmin to Edwardsiella ictaluri infection and iron overload in channel catfish (Ictalurus punctatus).

Ceruloplasmin is a serum ferroxidase that carries more than 90% of the copper in plasma and has documented roles in iron homeostasis as well as antioxidative functions. In our previous studies, it has been shown that the ceruloplasmin gene is strongly up-regulated in catfish during challenge with Edwardsiella ictaluri. However, little is known about the function of this gene in teleost fish. The objective of this study, therefore, was to characterize the ceruloplasmin gene from channel catfish, determine its genomic organization, profile its patterns of tissue expression, and establish its potential for physiological antioxidant responses in catfish after bacterial infection with E. ictaluri and iron treatment. The genomic organization suggested that the catfish ceruloplasmin gene had 20 exons and 19 introns, encoding 1074 amino acids. Exon sizes of the catfish ceruloplasmin gene were close to or identical with mammalian and zebrafish homologs. Further phylogenetic analyses suggested that the gene was highly conserved through evolution. The catfish ceruloplasmin gene was mapped to both the catfish physical map and linkage map. The catfish ceruloplasmin gene was mainly expressed in liver with limited expression in other tissues, and it was significantly up-regulated in the liver after bacterial infection alone or after co-injection with bacteria and iron-dextran, while expression was not significantly induced with iron-dextran treatment alone.

Molecular characterization and expression analysis of Cathepsin B and L cysteine proteases from rock bream (Oplegnathus fasciatus).

Cathepsins are lysosomal cysteine proteases of the papain family that play an important role in intracellular protein degradation and turn over within the lysosomal system. In the present study, full-length sequences of cathepsin B (RbCathepsin B) and L (RbCathepsin L) were identified after transcriptome sequencing of rock bream Oplegnathus fasciatus mixed tissue cDNA. Cathepsin B was composed of 330 amino acid residues with 36 kDa predicted molecular mass. RbCathepsin L contained 336 amino acid residues encoding for a 38 kDa predicted molecular mass protein. The sequencing analysis results showed that both cathepsin B and L contain the characteristic papain family cysteine protease signature and active sites for the eukaryotic thiol proteases of cysteine, asparagine and histidine. In addition, RbCathepsin L contained EF hand Ca(2+) binding and cathepsin propeptide inhibitor domains. The rock bream cathepsin B and L showed the highest amino acid identity of 90 and 95% to Lutjanus argentimaculatus cathepsin B and Lates calcarifer cathepsin L, respectively. By phylogenetic analysis, cathepsin B and L exhibited a high degree of evolutionary relationship to respective cathepsin family members of the papain superfamily. Quantitative real-time RT-PCR analysis results confirmed that the expression of cathepsin B and L genes was constitutive in all examined tissues isolated from un-induced rock bream. Moreover, activation of RbCathepsin B and L mRNA was observed in both lipopolysaccharide (LPS) and Edwardsiella tarda challenged liver and blood cells, indicating a role of immune response in rock bream.

Compliance with hand hygiene in patients with meticillin-resistant Staphylococcus aureus and extended-spectrum ß-lactamase-producing enterobacteria.

Hand hygiene is considered to be the single most effective measure to prevent healthcare-associated infection. Although there have been several reports on hand hygiene compliance, data on patients with multidrug-resistant (MDR) organisms in special isolation conditions are lacking. Therefore, we conducted a prospective observational study of indications for, and compliance with, hand hygiene in patients colonised or infected with meticillin-resistant Staphylococcus aureus (MRSA) or extended-spectrum ß-lactamase (ESBL)-producing enterobacteria in surgical intensive and intermediate care units. Hand disinfectant used during care of patients with MRSA was measured. Observed daily hand hygiene indications were higher in MRSA isolation conditions than in ESBL isolation conditions. Observed compliance rates were 47% and 43% for the MRSA group and 54% and 51% for the ESBL group in the surgical intensive care unit and the intermediate care unit, respectively. Compliance rates before patient contact or aseptic tasks were significantly lower (17-47%) than after contact with patient, body fluid or patient's surroundings (31-78%). Glove usage instead of disinfection was employed in up to 100% before patient contact. However, compliance rates calculated from disinfectant usage were two-fold lower (intensive care: 24% vs 47%; intermediate care: 21% vs 43%). This study is the first to provide data on hand hygiene in patients with MDR bacteria and includes a comparison of observed and calculated compliance. Compliance is low in patients under special isolation conditions, even for the indications of greatest impact in preventing healthcare-associated infections. These data may help to focus measures to reduce transmission of MDR bacteria and improve patient safety.

Modulation of hepatic cytochrome P450s by Citrobacter rodentium infection in interleukin-6- and interferon-{gamma}-null mice.

After infection with Citrobacter rodentium, murine hepatic cytochrome P450 (P450) mRNAs are selectively regulated. Several serum proinflammatory cytokines are elevated, the most abundant being interleukin-6 (IL6). To elucidate the role of cytokines in the regulation of P450s during infection, we orally infected wild-type, IL6(-/-), or interferon-γ(-/-) [IFNγ(-/-)] female C57BL/6J mice with C. rodentium and analyzed hepatic P450 expression 7 days later. The majority of P450 mRNAs were equally affected by infection in each genotype, indicating that IL6 and IFNγ are not the primary mediators of P450 down-regulation in this disease model. The down-regulation of CYP3A11 and CYP3A13 and induction of CYP2D9 mRNAs were attenuated in the IL6(-/-) mice, suggesting a role of IL6 in the regulation of only these P450s. Similar evidence implicated IFNγ in the regulation of CYP2D9, CYP2D22, CYP3A11, CYP3A25, and CYP4F18 mRNAs in C. rodentium infection and CYP2B9, CYP2D22, and CYP2E1 in the bacterial lipopolysaccharide model of inflammation. This is the first indication of an in vivo role for IFNγ in hepatic P450 regulation in disease states. The deficiency of IL6 or IFNγ affected serum levels of the other cytokines. Moreover, experiments in cultured hepatocytes demonstrated that tumor necrosis factor α (TNFα) is the most potent and efficacious of the cytokines tested in the regulation of murine P450 expression. It is therefore possible that part of the IFNγ(-/-) and IL6(-/-) phenotypes could be attributed to the reduced levels of TNFα and part of the IFNγ(-/-) phenotype could be caused by reduced levels of IL6.

The iron-cofactored superoxide dismutase of Edwardsiella tarda inhibits macrophage-mediated innate immune response.

Edwardsiella tarda is a Gram-negative bacterium that can infect a wide variety of marine and freshwater fish and cause severe economic losses worldwide. With an aim to elucidate the virulence mechanism of E. tarda, we in this study cloned and analyzed the function of an iron-cofactored superoxide dismutase (FeSOD) from a pathogenic E. tarda strain TX01 isolated from diseased fish. FeSOD is 192-residue in length and contains domain structures that are conserved among iron/manganese superoxide dismutases. Recombinant FeSOD purified from Escherichia coli exhibits apparent superoxide dismutase activity. Quantitative real-time RT-PCR analysis indicated that FeSOD expression is significantly upregulated immediately following TX01 infection of Japanese flounder (Paralichthys olivaceus) head kidney (HK) macrophages and cultured FG cells. Compared to the wild type strain TX01, the FeSOD mutant strain TXSod is (i) more sensitive to H(2)O(2)-induced oxidative damage, (ii) less resistant against serum- and macrophage-mediated bacterial killing, (iii) significantly weakened in the ability to invade into FG cells and to disseminate in fish blood and liver, and (iv) deficient in blocking macrophage respiratory burst activity and production of reactive oxygen species. Furthermore, HK macrophages infected by TXSod exhibits significantly increased expression of inflammatory cytokines compared to macrophages infected by TX01. Taken together, these results indicate that FeSOD is a virulence factor that plays an important role in the pathogenicity of E. tarda by inhibiting macrophage-mediated innate immune response.

Prevalence of extended-spectrum beta-lactamases-producing microorganisms in nosocomial patients and molecular characterization of the shv type isolates

The emergence of Extended-Spectrum Beta-Lactamase (ESBL)-producing microorganisms in Brazilian hospitals is a challenge that concerns scientists, clinicians and healthcare institutions due to the serious risk they pose to confined patients. The goal of this study was the detection of ESBL production by clinical strains of Escherichia coli and Klebsiella sp. isolated from pus, urine and blood of patients at Hospital Universitário Santa Maria, Rio Grande Sul, RS, Brazil and the genotyping of the isolates based on bla SHV genes. The ESBL study was carried out using the Combined Disc Method, while Polymerase Chain Reaction (PCR) was used to study the bla SHV genes. Of the 90 tested isolates, 55 (61.1 percent) were identified as ESBL-producing by the combined disk method. The bla SHV genes were found in 67.8 percent of these microorganisms. K. pneumoniae predominated in the samples, presenting the highest frequency of positive results from the combined disk and PCR.

Invited review: Breaking barriers--attack on innate immune defences by omptin surface proteases of enterobacterial pathogens.

The omptin family of Gram-negative bacterial transmembrane aspartic proteases comprises surface proteins with a highly conserved beta-barrel fold but differing biological functions. The omptins OmpT of Escherichia coli, PgtE of Salmonella enterica, and Pla of Yersinia pestis differ in their substrate specificity as well as in control of their expression. Their functional differences are in accordance with the differing pathogenesis of the infections caused by E. coli, Salmonella, and Y. pestis, which suggests that the omptins have adapted to the life-styles of their host species. The omptins Pla and PgtE attack on innate immunity by affecting the plasminogen/plasmin, complement, coagulation, fibrinolysis, and matrix metalloproteinase systems, by inactivating antimicrobial peptides, and by enhancing bacterial adhesiveness and invasiveness. Although the mechanistic details of the functions of Pla and PgtE differ, the outcome is the same: enhanced spread and multiplication of Y. pestis and S. enterica in the host. The omptin OmpT is basically a housekeeping protease but it also degrades cationic antimicrobial peptides and may enhance colonization of E. coli at uroepithelia. The catalytic residues in the omptin molecules are spatially conserved, and the differing polypeptide substrate specificities are dictated by minor sequence variations at regions surrounding the catalytic cleft. For enzymatic activity, omptins require association with lipopolysaccharide on the outer membrane. Modification of lipopolysaccharide by in vivo conditions or by bacterial gene loss has an impact on omptin function. Creation of bacterial surface proteolysis is thus a coordinated function involving several surface structures.

Regulation of hepatic cytochrome P450 expression in mice with intestinal or systemic infections of citrobacter rodentium.

We reported previously that infection of C3H/HeOuJ (HeOu) mice with the murine intestinal pathogen Citrobacter rodentium caused a selective modulation of hepatic cytochrome P450 (P450) gene expression in the liver that was independent of the Toll-like receptor 4. However, HeOu mice are much more sensitive to the pathogenic effects of C. rodentium infection, and the P450 down-regulation was associated with significant morbidity in the animals. Here, we report that oral infection of C57BL/6 mice with C. rodentium, which produced only mild clinical signs and symptoms, produced very similar effects on hepatic P450 expression in this strain. As in HeOu mice, CYP4A mRNAs and proteins were among the most sensitive to down-regulation, whereas CYP4F18 was induced. CYP2D9 mRNA was also induced 8- to 9-fold in the C57BL/6 mice. The time course of P450 regulation followed that of colonic inflammation and bacterial colonization, peaking at 7 to 10 days after infection and returning to normal at 15 to 24 days as the infection resolved. These changes also correlated with the time course of significant elevations in the serum of the proinflammatory cytokines interleukin (IL)-6 and tumor necrosis factor-alpha, as well as of interferon-gamma and IL-2, with serum levels of IL-6 being markedly higher than those of the other cytokines. Intraperitoneal administration of C. rodentium produced a rapid down-regulation of P450 enzymes that was quantitatively and qualitatively different from that of oral infection, although CYP2D9 was induced in both models, suggesting that the effects of oral infection on the liver are not due to bacterial translocation.

Nosocomial spread of armA-mediated high-level aminoglycoside resistance in Enterobacteriaceae isolates producing CTX-M-3 beta-lactamase in a cancer hospital in Bulgaria.

1,310 Enterobacteriaceae, 242 Pseudomonas aeruginosa and 97 Acinetobacter baumannii clinical isolates collected at a cancer hospital in Bulgaria were screened for the presence of 16S rRNA methylases. The armA methylase gene was identified in 20 (1.5%) Enterobacteriaceae (7 Klebsiella pneumoniae, 3 Escherichia coli, 3 Serratia marcescens, 3 Citrobacter freundii , 3 Enterobacter cloacae and 1 Klebsiella oxytoca). ArmA-mediated aminoglycoside resistance was transferable by conjugation and carried by closely related IncL/M plasmids which also carried ant3"9, dfrXII, sul1, bla(TEM-1), and bla(CTX-M-3) genes encoding resistance to streptomycin-spectinomycin, trimethoprim, sulfonamides, and ss-lactams, respectively. Most of the isolates were genetically different according to PFGE but shared similar restriction patterns of the armA -encoding plasmids. Our findings highlight the strong association of armA and bla(CTX-M-3) extended-spectrum ss-lactamase genes across various species in the family Enterobacteriaceae . The spread of multiresistant isolates expressing 16S rRNA methylases and ESBLs is a worrisome development requiring continuous monitoring.

Outer membrane protein A expression in Enterobacter sakazakii is required to induce microtubule condensation in human brain microvascular endothelial cells for invasion.

Enterobacter sakazakii (ES) causes neonatal meningitis and necrotizing enterocolitis with case-fatality rates among infected infants ranging from 40 to 80%. Very little is known about the mechanisms by which these organisms cause disease. Here, we demonstrate that ES invades human brain microvascular endothelial cells (HBMEC) with higher frequency when compared with epithelial cells and endothelial cells from different origins. The entry of ES into HBMEC requires the expression of outer membrane protein A (OmpA), as the OmpA-deletion mutant was sevenfold less invasive than the wild type ES and the bacterium does not multiply inside HBMEC. Anti-OmpA antibodies generated against the OmpA of Escherichia coli K1, which also recognize the OmpA of ES, did not prevent the invasion of ES in HBMEC. ES invasion depends on microtubule condensation in HBMEC and is independent of actin filament reorganization. Both PI3-kinase and PKC-alpha were activated during ES entry into HBMEC between 15 min and 30 min of infection. Concomitantly, overexpression of dominant negative forms of PI3-kinase and PKC-alpha significantly inhibited the invasion of ES into HBMEC. In summary, ES invasion of HBMEC is dependent on the expression of OmpA similar to that of E. coli K1; however, the epitopes involved in the interaction with HBMEC appears to be different.

Expression of UDP-glucuronosyltransferase isoform mRNAs during inflammation and infection in mouse liver and kidney.

Inflammation or infection down-regulates the activity and expression of cytochrome P450 (P450) enzymes involved in hepatic drug clearance, possibly altering drug effectiveness and leading to toxicity. The regulation of UDP-glucuronosyltransferases (UGTs) in inflammation and infection is less well characterized. To determine the response of hepatic and renal UGTs during inflammation and infection, mice were administered either saline or 1 mg/kg lipopolysaccharide (LPS) (16 h), or Citrobacter rodentium by oral gavage (6 days). Hepatic mRNA expression of UGT1A1, 1A9, and 2B5 was similarly down-regulated after LPS exposure and C. rodentium infection, whereas UGT1A2 and 1A6 mRNAs were unchanged. Effects of C. rodentium infection did not require a functional Toll-like receptor 4. Conversely, renal UGT isoforms were relatively unaffected, except for UGT2B5 induction after LPS treatment. Regulation of UGTs during the inflammatory response exhibits similarities to and differences from regulation of P450s, and may be cytokine-mediated.