Proteogenomics of Non-smoking Lung Cancer in East Asia Delineates Molecular Signatures of Pathogenesis and Progression.

Lung cancer in East Asia is characterized by a high percentage of never-smokers, early onset and predominant EGFR mutations. To illuminate the molecular phenotype of this demographically distinct disease, we performed a deep comprehensive proteogenomic study on a prospectively collected cohort in Taiwan, representing early stage, predominantly female, non-smoking lung adenocarcinoma. Integrated genomic, proteomic, and phosphoproteomic analysis delineated the demographically distinct molecular attributes and hallmarks of tumor progression. Mutational signature analysis revealed age- and gender-related mutagenesis mechanisms, characterized by high prevalence of APOBEC mutational signature in younger females and over-representation of environmental carcinogen-like mutational signatures in older females. A proteomics-informed classification distinguished the clinical characteristics of early stage patients with EGFR mutations. Furthermore, integrated protein network analysis revealed the cellular remodeling underpinning clinical trajectories and nominated candidate biomarkers for patient stratification and therapeutic intervention. This multi-omic molecular architecture may help develop strategies for management of early stage never-smoker lung adenocarcinoma.

Intelligent Phase Contrast Meta-Microscope System.

Phase contrast imaging techniques enable the visualization of disparities in the refractive index among various materials. However, these techniques usually come with a cost: the need for bulky, inflexible, and complicated configurations. Here, we propose and experimentally demonstrate an ultracompact meta-microscope, a novel imaging platform designed to accomplish both optical and digital phase contrast imaging. The optical phase contrast imaging system is composed of a pair of metalenses and an intermediate spiral phase metasurface located at the Fourier plane. The performance of the system in generating edge-enhanced images is validated by imaging a variety of human cells, including lung cell lines BEAS-2B, CLY1, and H1299 and other types. Additionally, we integrate the ResNet deep learning model into the meta-microscope to transform bright-field images into edge-enhanced images with high contrast accuracy. This technology promises to aid in the development of innovative miniature optical systems for biomedical and clinical applications.

Regulation of dendritic cell maturation in osimertinib-treated lung adenocarcinoma patients.

Osimertinib (OSI), a third-generation tyrosine kinase inhibitor (TKI), efficiently benefits lung adenocarcinoma (LUAD) patients with epidermal growth factor receptor (EGFR) mutations. However, combined OSI and immune checkpoint inhibitor in EGFR-mutant patients increases the incidence of interstitial lung disease (ILD), although the mechanism is unknown. Here, we investigated the interaction between dendritic cells (DCs), a potential critical player in ILD, and OSI. Seventeen LUAD patients received TKI therapy, and only the OSI therapy group (N = 10) showed a significant increase in CD40 and CD83 on immature DCs (iDCs), and an elevated trend for both markers on mature DCs (mDCs) during short- and long-term OSI therapy. Our results indicated that OSI therapy may potentially activate DC functions, which might increase the potential immune toxicity when combined with onco-immunotherapy.

A proposed approach to confirm heroin administration - Regional differences in heroin purity is a major factor.

In forensic toxicology, a marker of street heroin use is urgent especially in the absence of urinary 6-monoacetylmorphine. ATM4G, the Glucuronide of Acetylated product of Thebaine compound 4 Metabolite (ATM4), arising from byproducts of street heroin synthesis has been considered as a useful marker in some European studies. However, whether ATM4G is a universal marker particularly in Southeast Asia due to 'street' heroin with high purity, it's still unclear. To investigate putative markers for different regions, ATM4G and other metabolites including the Acetylated product of Thebaine compound 3 Metabolite (ATM3) and thebaol, also originated from thebaine were detected in 552 urine samples from heroin users in Taiwan. Results were compared with that from samples collected in the UK and Germany. Only a sulfo-conjugate of ATM4, ATM4S, was detected in 28 Taiwanese users using a sensitive MS3 method whilst out of 351 samples from the UK and Germany, ATM4G was present in 91. Thebaol-glucuronide was first time detected in 118. No markers were detected in urine following herbal medicine use or poppy seed ingestion. The presence of ATM4S/ATM4G might be affected by ethnicities and heroin supplied in regions. Thebaol-glucuronide is another putative marker with ATM4G and ATM4S for street heroin use.

The M1/M2 spectrum and plasticity of malignant pleural effusion-macrophage in advanced lung cancer.

BACKGROUND: Malignant pleural effusion (MPE)-macrophage (Mφ) of lung cancer patients within unique M1/M2 spectrum showed plasticity in M1-M2 transition. The M1/M2 features of MPE-Mφ and their significance to patient outcomes need to be clarified; furthermore, whether M1-repolarization could benefit treatment remains unclear. METHODS: Total 147 stage-IV lung adenocarcinoma patients undergoing MPE drainage were enrolled for profiling and validation of their M1/M2 spectrum. In addition, the MPE-Mφ signature on overall patient survival was analyzed. The impact of the M1-polarization strategy of patient-derived MPE-Mφ on anti-cancer activity was examined. RESULTS: We found that MPE-Mφ expressed both traditional M1 (HLA-DRA) and M2 (CD163) markers and showed a wide range of M1/M2 spectrum. Most of the MPE-Mφ displayed diverse PD-L1 expression patterns, while the low PD-L1 expression group was correlated with higher levels of IL-10. Among these markers, we identified a novel two-gene MPE-Mφ signature, IL-1ß and TGF-ß1, representing the M1/M2 tendency, which showed a strong predictive power in patient outcomes in our MPE-Mφ patient cohort (N = 60, p = 0.013) and The Cancer Genome Atlas Lung Adenocarcinoma dataset (N = 478, p < 0.0001). Significantly, ß-glucan worked synergistically with IFN-γ to reverse the risk signature by repolarizing the MPE-Mφ toward the M1 pattern, enhancing anti-cancer activity. CONCLUSIONS: We identified MPE-Mφ on the M1/M2 spectrum and plasticity and described a two-gene M1/M2 signature that could predict the outcome of late-stage lung cancer patients. In addition, we found that "re-education" of these MPE-Mφ toward anti-cancer M1 macrophages using clinically applicable strategies may overcome tumor immune escape and benefit anti-cancer therapies.

Determination of synthetic cathinone α-pyrrolidinovalero-phenone and its metabolite in urine using solid-phase extraction and gas chromatography-mass spectrometry.

RATIONALE: The presence of α-pyrrolidinovalerophenone (α-PVP) and its metabolites in urine is evidence of the administration of α-PVP. A toxicological challenge is that the metabolites of α-PVP exhibit amphoteric properties, which make them unsuitable for detection using gas chromatography-mass spectrometry (GC/MS). In the study reported, proper derivatization and sample extraction were essential for improving the sensitivity for GC/MS analysis. METHODS: An automated solid-phase extraction (SPE) method has been developed and optimized. The derivatization efficiency was tested using longer reaction time and the addition of polar pyridine into a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane. Method validation, including linearity, limit of detection, precision, accuracy, and recovery, was evaluated using automatic SPE and GC/MS. RESULTS: The results suggested that adding pyridine to BSTFA (1:1, v/v) significantly improved derivatization efficiency and precision. After optimization, the linear range was from 25 to 1000 ng mL-1 with R2 > 0.9950. The limit of detection was 5 ng mL-1 for α-PVP and 25 ng mL-1 for OH-α-PVP. The recovery for SPE was over 88%. The inter-day and intra-day precisions were less than 15%. A forensic sample has been found containing α-PVP (67.3 ng mL-1 ) and OH-α-PVP (560.2 ng mL-1 ). CONCLUSIONS: This study is the first to validate an auto-SPE-GC/MS method for the quantification and qualification of α-PVP and OH-α-PVP in urine. We have successfully improved the derivatization efficiency and developed a sensitive and semi-automatic approach. This approach is desirable for the detection of synthetic cathinone at trace levels in biological samples.

Astaxanthin Counteracts Vascular Calcification In Vitro Through an Early Up-Regulation of SOD2 Based on a Transcriptomic Approach.

Vascular calcification (VC) is a critical contributor to the rising cardiovascular risk among at-risk populations such as those with diabetes or renal failure. The pathogenesis of VC involves an uprising of oxidative stress, for which antioxidants can be theoretically effective. However, astaxanthin, a potent antioxidant, has not been tested before for the purpose of managing VC. To answer this question, we tested the efficacy of astaxanthin against VC using the high phosphate (HP)-induced vascular smooth muscle cell (VSMC) calcification model. RNAs from treated groups underwent Affymetrix microarray screening, with intra-group consistency and inter-group differential expressions identified. Candidate hub genes were selected, followed by validation in experimental models and functional characterization. We showed that HP induced progressive calcification among treated VSMCs, while astaxanthin dose-responsively and time-dependently ameliorated calcification severities. Transcriptomic profiling revealed that 3491 genes exhibited significant early changes during VC progression, among which 26 potential hub genes were selected based on closeness ranking and biologic plausibility. SOD2 was validated in the VSMC model, shown to drive the deactivation of cellular senescence and enhance antioxidative defenses. Astaxanthin did not alter intracellular reactive oxygen species (ROS) levels without HP, but significantly lowered ROS production in HP-treated VSMCs. SOD2 knockdown prominently abolished the anti-calcification effect of astaxanthin on HP-treated VSMCs, lending support to our findings. In conclusion, we demonstrated for the first time that astaxanthin could be a potential candidate treatment for VC, through inducing the up-regulation of SOD2 early during calcification progression and potentially suppressing vascular senescence.

MicroRNA-125b in vascular diseases: An updated systematic review of pathogenetic implications and clinical applications.

Epigenetic changes, particularly non-coding RNAs, have been implicated extensively in the pathogenesis of vascular diseases. Specific miRNAs are involved in the differentiation, phenotypic switch, proliferation, apoptosis, cytokine production and matrix deposition of endothelial cells and/or vascular smooth muscle cells. MicroRNA-125b has been studied in depth for its role in carcinogenesis with a double-edged role; that is, it can act as an oncogene in some cancer types and as a tumour suppressor gene in others. However, cumulative evidence from the use of advanced miRNA profiling techniques and bioinformatics analysis suggests that miR-125b can be a potential mediator and useful marker of vascular diseases. Currently, the exact role of miR-125b in vascular diseases is not known. In this systematic review, we intend to provide an updated compilation of all the recent findings of miR-125b in vascular diseases, using a systematic approach of retrieving data from all available reports followed by data summarization. MiR-125b serves as a pathogenic player in multiple vascular pathologies involving endothelia and vascular smooth muscle cells and also serves as a diagnostic marker for vascular diseases. We further provide a computational biologic presentation of the complex network of miR-125b and its target genes within the scope of vascular diseases.

Gonadotropin-releasing hormone agonist induces downregulation of tensin 1 in women with endometriosis.

INTRODUCTION: Many cell migration-related molecules are associated with endometriosis. Tensin 1 (TNS1), which has been implicated in cell migration, may play a role in endometriosis. The study goal was to evaluate the TNS1 expression in endometrial tissue and serum from women with endometriosis treated with gonadotropin-releasing hormone agonist (GnRHa). MATERIAL AND METHODS: Tissue and serum samples were collected from women with endometriosis who were treated (n = 29) with GnRHa or untreated (n = 30). TNS1 mRNA was examined using quantitative PCR. TNS1 protein levels in tissue and serum samples were investigated using Western blot, immunohistochemistry and ELISA. Eleven women with endometriosis participated in a follow-up investigation of serum TNS1 before and after GnRHa treatment. RESULTS: TNS1 mRNA (P = 0.006) and protein (P = 0.001) were significantly downregulated in endometriotic tissue from women with endometriosis who received GnRHa. Immunolocalization of TNS1 showed strong expression in the epithelial and stromal cells of endometriotic tissue from women untreated with GnRHa, whereas endometriotic tissue from GnRHa-treated women showed low TNS1 expression. Follow-up monitoring of serum TNS1 concentration in 11 women showed an average decrease in concentration of 53%, from 294.9 ± 66.69 to 140.3 ± 55.21 pg/mL, following GnRHa treatment (P = 0.003). CONCLUSIONS: GnRHa induces downregulation of TNS1 in tissue and serum in women with endometriosis. These results emphasize the importance TNS1 as a potential therapeutic molecular target for the treatment of endometriosis with GnRHa.

Decreased Level of Neurotrophic Factor Neuritin 1 in Women with Ovarian Endometriosis after Receiving Gonadotropin-Releasing Hormone Agonist Treatment.

This study aimed to investigate the effect of gonadotropin-releasing hormone agonist (GnRHa) treatment on the expression of neuritin 1 (NRN1) in women with ovarian endometriosis. We collected tissues and serum from women with endometriosis treated with (n = 45) or without (n = 37) GnRHa. NRN1 mRNA and protein levels were measured using qPCR and Western blot. Immunolocalization of NRN1 in endometriotic tissues was examined using immunohistochemistry. In addition, a follow-up study was carried out to monitor the serum level of NRN1 in patients before and after GnRHa treatment. Both mRNA (p = 0.046) and protein (p = 0.0155) levels of NRN1 were significantly lower in endometriotic tissues from patients receiving GnRHa treatment compared to the untreated group. Both epithelial and stromal cells of endometriotic tissues from untreated women with endometriosis exhibited stronger staining of NRN1 but not in those who were treated with GnRHa. The follow-up study showed that the serum level of the NRN1 concentration decreased significantly from 1149 ± 192.3 to 379.2 ± 80.16 pg/mL after GnRHa treatment (p = 0.0098). The expression of NRN1 was significantly lower in women with ovarian endometriosis treated with GnRHa. These results suggest that NRN1 may be a biomarker response to the effect of GnRHa treatment for patients with ovarian endometriosis.

Circulating MicroRNA-125b Predicts the Presence and Progression of Uremic Vascular Calcification.

OBJECTIVE: Vascular calcification (VC) is a major cause of mortality in patients with end-stage renal diseases. Biomarkers to predict the progression of VC early are in urgent demand. APPROACH AND RESULTS: We identified circulating, cell-free microRNAs as potential biomarkers using in vitro VC models in which both rat and human aortic vascular smooth muscle cells were treated with high levels of phosphate to mimic uremic hyperphosphatemia. Using an Affymetrix microRNA array, we found that miR-125b and miR-382 expression levels declined significantly as biomineralization progressed, but this decline was only observed for miR-125b in the culture medium. A time-dependent decrease in aortic tissue and serum miR-125b levels was also found in both ex vivo and in vivo renal failure models. We examined the levels of circulating, cell-free miR-125b in sera from patients with end-stage renal diseases (n=88) and found an inverse association between the severity of VC and the circulating miR-125b level, irrespective of age or mineral-related hormones (odds ratio, 0.71; P=0.03). Furthermore, serum miR-125b levels on enrollment can predict VC progression years later (for high versus low, odds ratio, 0.14; P<0.01; for the highest versus lowest tertile and middle versus lowest tertile, odds ratio, 0.55 and 0.13; P=0.3 and <0.01, respectively). The uremic VC prediction efficacy using circulating miR-125b levels was also observed in an independent cohort (n=135). CONCLUSIONS: The results suggest that serum miR-125b levels are associated with VC severity and serve as a novel predictive marker for the risk of uremia-associated calcification progression.

MicroRNA signature predicts survival and relapse in lung cancer.

We investigated whether microRNA expression profiles can predict clinical outcome of NSCLC patients. Using real-time RT-PCR, we obtained microRNA expressions in 112 NSCLC patients, which were divided into the training and testing sets. Using Cox regression and risk-score analysis, we identified a five-microRNA signature for the prediction of treatment outcome of NSCLC in the training set. This microRNA signature was validated by the testing set and an independent cohort. Patients with high-risk scores in their microRNA signatures had poor overall and disease-free survivals compared to the low-risk-score patients. This microRNA signature is an independent predictor of the cancer relapse and survival of NSCLC patients.

Activation of mitochondrial STAT-3 and reduced mitochondria damage during hypothermia treatment for post-cardiac arrest myocardial dysfunction.

While therapeutic hypothermia improves the outcomes of individuals in cardiac arrest, the hemodynamic responses and mechanisms which underlie hypothermia-induced cardioprotection are not fully understood. Therefore, we investigated the mechanism by which induced hypothermia preserves cardiac function and protects against mitochondrial damage following cardiac arrest. Cardiac arrest was induced in adult male Wistar rats by asphyxiation for 8.5 min. Following resuscitation, the animals were randomly assigned to a hypothermia (32 °C) or normothermia (37 °C) group. Monitoring results showed that cardiac output at the fourth hour after resuscitation was significantly better in rats treated with hypothermia when compared to rats treated with normothermia (P < 0.01). Examinations by transmission electron microscopy showed that mitochondria in the left ventricle of rats in the hypothermia group were significantly less swollen compared to such mitochondria in the normothermia group (P < 0.001). Additionally, opening of mitochondrial permeability transition pores occurred less frequently in the hypothermic group. While complex I/III activity in the electron transport reaction was damaged after cardiac arrest and resuscitation, the degree of injury was ameliorated by hypothermia treatment (P < 0.05). The amount of STAT-3 phosphorylated at tyrosine 705 and its expression in mitochondria were significantly higher under hypothermia treatment compared to normothermia treatment. In vitro studies showed that inhibition STAT-3 activation abolished the ability of hypothermia to protect H9C2 cardiomyocytes against injury produced by simulated ischemia and reperfusion. Therapeutic hypothermia treatment can ameliorate cardiac dysfunction and help preserve both mitochondrial integrity and electron transport activity.

Prolonged cooling duration mitigates myocardial and cerebral damage in cardiac arrest.

BACKGROUND: The purpose of this study was to investigate the effect of prolonged cooling on cardiac and cerebral injury in animals under cardiac arrest. METHODS: Adult male Wistar rats were equally randomized to normothermia, 5H1, 5H2, 7H1, 7H2, and 7H4 groups. The first number in the group name indicated ventricular fibrillation duration (minutes), the middle H indicated hypothermia, and the last number signified hypothermia duration (hours). Ventricular fibrillation was induced and untreated for 5 minutes (normothermia, 5H1, and 5H2) or 7 minutes (7H1, 7H2, and 7H4) followed by 1 minute of cardiopulmonary resuscitation followed by electric shocks. Hypothermia was initiated simultaneously with cardiopulmonary resuscitation initiation and maintained for 1 hour (5H1 and 7H1), 2 hours (5H2 and 7H2) or 4 hours (7H4). RESULTS: There were 12 rats in each group. Compared with the 7H1 group, the 7H4 group had significantly better systolic function (dp/dt40) and cardiac output within the early postcardiac arrest period. Histologic examination disclosed less myocardial and hippocampal damage in the 7H4 group than the 7H1 group and in the 5H2 group than the 5H1 group. Plasma troponin I, fatty acid-binding protein, and S-100ß concentrations were significantly lower in the 7H4 and 5H2 groups. The 7H4 and 5H2 groups survived statistically longer than the groups with shorter cooling duration. CONCLUSION: Slightly prolonging hypothermia may mitigate myocardial and cerebral damage and improve survival and neurologic outcomes in a rat model of ventricular fibrillation cardiac arrest.

Occurrence of nonylphenol and bisphenol A in household water pipes made of different materials.

We assessed the occurrence of nonylphenol (NP) and bisphenol A (BPA) in tap water supplied through polyvinyl chloride (PVC), stainless steel, and galvanized pipes. Water samples were collected from selected households in Taipei and Kaohsiung (Northern and Southern Taiwan, respectively) in different seasons to elucidate the effects of pipeline materials and ambient temperatures on NP and BPA concentrations in tap water. We detected higher concentrations of NP in tap water from households using PVC pipes (64-195 ng/L) than from those using stainless steel pipes (17-44 ng/L) and galvanized pipes (27-96 ng/L). To verify that water can absorb NP and BPA from PVC pipes, we sealed Milli-Q and tap water in PVC and stainless steel pipes to assess the potential release of NP and BPA from the pipes into the water. Both NP and BPA concentrations initially increased with contact time in the PVC pipes, and the concentration profiles during the retention appeared to be more strongly affected by ambient temperatures. Concentration variations in the stainless steel pipes were smaller than those in the PVC pipes.

Focal amplification of HOXD-harboring chromosome region is implicated in multiple-walled carbon nanotubes-induced carcinogenicity.

Multiple-walled carbon nanotubes (MWCNTs) may cause carcinogenesis. We found that long-term exposure to MWCNTs can induce irreversible oncogenic transformation of human bronchial epithelial cells and tumorigenicity in vivo. A genome-wide array-comparative genomic hybridization (aCGH) analysis revealed global chromosomal aberration in MWCNTs-treated clones, predominantly at chromosome 2q31-32, where the potential oncogenes HOXD9 and HOXD13 are located. Functional assays confirmed that this variation can modulate oncogenic signaling and plays a part in MWCNTs-induced tumorigenesis, suggesting that MWCNTs are carcinogens that act by altering genomic stability and oncogenic copy numbers.

Comammox Nitrospira cooperate with anammox bacteria in a partial nitritation-anammox membrane bioreactor treating low-strength ammonium wastewater at high loadings.

Research has revealed that comammox Nitrospira and anammox bacteria engage in dynamic interactions in partial nitritation-anammox reactors, where they compete for ammonium and nitrite or comammox Nitrospria supply nitrite to anammox bacteria. However, two gaps in the literature are present: the know-how to manipulate the interactions to foster a stable and symbiotic relationship and the assessment of how effective this partnership is for treating low-strength ammonium wastewater at high hydraulic loads. In this study, we employed a membrane bioreactor designed to treat synthetic ammonium wastewater at a concentration of 60 mg N/L, reaching a peak loading of 0.36 g N/L/day by gradually reducing the hydraulic retention time to 4 hr. Throughout the experiment, the reactor achieved an approximately 80 % nitrogen removal rate through strategically adjusting intermittent aeration at every stage. Notably, the genera Ca. Kuenena, Nitrosomonas, and Nitrospira collectively constituted approximately 40 % of the microbial community. Under superior intermittent aeration conditions, the expression of comammox amoA was consistently higher than that of Nitrospira nxrB and AOB amoA in the biofilm, despite the higher abundance of Nitrosomonas than comammox Nitrospira, implying that the biofilm environment is favorable for fostering cooperation between comammox and anammox bacteria. We then assessed the in situ activity of comammox Nitrospira in the reactor by selectively suppressing Nitrosomonas using 1-octyne, thereby confirming that comammox Nitrospira played the primary role in facilitating the nitritation (33.1 % of input ammonium) rather than complete nitrification (7.3 % of input ammonium). Kinetic analysis revealed a specific ammonia-oxidizing rate 5.3 times higher than the nitrite-oxidizing rate in the genus Nitrospira, underscoring their critical role in supplying nitrite. These findings provide novel insights into the cooperative interplay between comammox Nitrospira and anammox bacteria, potentially reshaping the management of nitrogen cycling in engineered environments, and aiding the development of microbial ecology-driven wastewater treatment technologies.

The HLJ1-targeting drug screening identified Chinese herb andrographolide that can suppress tumour growth and invasion in non-small-cell lung cancer.

HLJ1 is a novel tumour suppressor and is a potential druggable target for non-small-cell lung cancer (NSCLC). In this report, using a promoter-containing enhancer region as the HLJ1-targeting drug-screening platform, we identified several herbal compounds from a Chinese herbal bank with the capacity to enhance HLJ1 promoter activity and suppress tumour growth and invasion of NSCLC. Among the herbal drugs identified, the andrographolide (from Andrographis paniculata [Burm. f.] Nees.) most significantly induced HLJ1 expression and suppressed tumorigenesis both in vitro and in vivo. The andrographolide upregulates HLJ1 via JunB activation, which modulates AP-2α binding at the MMP-2 promoter and represses the expression of MMP-2. In addition, silencing of HLJ1 partially reverses the inhibition of cancer-cell invasion by andrographolide. Microarray transcriptomic analysis was performed to comprehensively depict the andrographolide-regulated signalling pathways. We showed that andrographolide can affect 939 genes (analysis of variance, false discovery rate < 0.05) that are dominantly involved in the cell cycle, apoptosis and adhesion-related biological signalling, including mitogen-activated protein kinase, focal adhesion and tight junction pathways, indicating the diverse effects of andrographolide on anticancer invasion and proliferation. In conclusion, the HLJ1-targeting drug-screening platform is useful for screening of novel anticancer compounds. Using this platform, we identified andrographolide is a promising new anticancer agent that could suppress tumour growth and invasion in NSCLC.

Citrobacter peritoneal dialysis peritonitis: rare occurrence with poor outcomes.

INTRODUCTION: Non-Pseudomonas gram-negative bacteria are responsible for an increasing proportion of cases of peritoneal dialysis (PD)-related peritonitis. The role of Citrobacter species in the etiology of PD-related peritonitis is often underestimated. In the present study, we aimed to describe the clinical features, laboratory findings, and short- and long-term outcomes in PD-related peritonitis caused by Citrobacter. METHODS: A retrospective review of all episodes of PD-related peritonitis caused by Citrobacter from a single center between 1990 and 2010 was performed. Clinical features, microbiological data, and outcomes of these episodes were analyzed. RESULTS: Citrobacter species was responsible for 11 PD-related episodes (1.8% of all peritonitis episodes) in 8 patients. Citrobacter freundii was the most common etiologic species (73%), and mixed growth was found in the other 3 episodes (27%). Approximately half (46%) of the episodes were associated with constipation and/or diarrhea. Of the Citrobacter isolates from all episodes, 54% were resistant to cefazolin, and only 18% were susceptible to cefmetazole. All isolates were susceptible to ceftazidime, cefepime, carbapenem, and aminoglycosides. More than half of the patients (54%) were hospitalized for index peritonitis, and 27% of the episodes involved a change in antibiotic medication. One patient had relapsing peritonitis caused by C. koseri (9%). The mortality rate of PD-related peritonitis caused by Citrobacter was 18%, and 89% of surviving patients developed technique failure requiring a modality switch after an average of 12 months of follow-up (range 1.2-31.2 months). CONCLUSION: PD-related peritonitis caused by Citrobacter is associated with poor outcomes, including high rates of antibiotic resistance, a high mortality rate, and a high rate of technique failure among survivors during the follow-up period.

Peritoneal dialysis peritonitis by anaerobic pathogens: a retrospective case series.

BACKGROUND: Bacterial infections account for most peritoneal dialysis (PD)-associated peritonitis episodes. However, anaerobic PD peritonitis is extremely rare and intuitively associated with intra-abdominal lesions. In this study, we examined the clinical characteristics of PD patients who developed anaerobic peritonitis. METHODS: We retrospectively identified all anaerobic PD peritonitis episodes from a prospectively collected PD registry at a single center between 1990 and 2010. Only patients receiving more than 3 months of PD were enrolled. We analyzed clinical features as well as outcomes of anaerobic PD peritonitis patients. RESULTS: Among 6 patients, 10 episodes of PD-associated peritonitis were caused by anaerobic pathogens (1.59% of all peritonitis episodes during study the period), in which the cultures from 5 episodes had mixed growth. Bacteroides fragilis was the most common species identified (4 isolates). Only 3 episodes were associated with gastrointestinal lesions, and 4 episodes were related to a break in sterility during exchange procedures. All anaerobic pathogens were susceptible to clindamycin and metronidazole, but penicillin resistance was noted in 4 isolates. Ampicillin/sulbactam resistance was found in 2 isolates. In 5 episodes, a primary response was achieved using the first-generation cephalosporin and ceftazidime or aminoglycoside. In 3 episodes, the first-generation cephalosporin was replaced with aminoglycosides. Tenckhoff catheter removal was necessary in 2 episodes. Only one episode ended with mortality (due to a perforated bowel). CONCLUSION: Anaerobic PD-associated peritonitis might be predominantly caused by contamination, rather than intra-abdominal events. Half of anaerobic PD-associated peritonitis episodes had polymicrobial growth. The overall outcome of anaerobic peritonitis is fair, with a high catheter survival rate.