Tharani Priya Thirumoorthy, Jobin John Jacob, Aravind Velmurugan
et al.
ABSTRACT The emergence and spread of Salmonella Typhi (S. Typhi) resistant to third-generation cephalosporins is a serious global health concern. In this study, we genomically characterized 142 cephalosporin-resistant S. Typhi strains isolated from India. Comparative genome analysis revealed the emergence of a new clone of ceftriaxone-resistant S. Typhi harboring three plasmids of the incompatibility groups IncFIB(K), IncX1, and IncFIB(pHCM2). Among these, the IncFIB(K) plasmid confers resistance to third-generation cephalosporins through the blaCTX-M-15 gene, along with other resistance determinants such as aph(3"), aph(6'), sul2, dfrA14, qnrS, and tet(A). Phylogenetic analysis showed that the isolates from Gujarat (n = 140/142) belong to a distinct subclade (genotype 4.3.1.2.2) within genotype 4.3.1.2 (H58 lineage II). Single nucleotide polymorphism-based phylogenetic analysis of the core genes in IncFIB(K) suggested a close relatedness of the plasmid backbone to that of IncFIB(K) from other Enterobacteriales, indicating that H58 lineage II possesses the capability to acquire MDR plasmids from these organisms. This could indicate the potential onset of a new wave of ceftriaxone-resistant S. Typhi in India. The implementation of control measures—such as vaccination and improved water, sanitation, and hygiene systems—is crucial in areas where MDR or extensively drug-resistant S. Typhi strains are prevalent to curb the spread and impact of these resistant strains.IMPORTANCETyphoid fever remains a global health concern, especially in areas lacking sanitation and clean water. The rise of drug-resistant strains complicates treatment, increasing illness, death, and healthcare expenses. Travel facilitates the spread of these strains worldwide. Multidrug-resistant and extensively drug-resistant (XDR) strains, including those resistant to first-line antibiotics and fluoroquinolones, pose significant challenges. Azithromycin and third-generation cephalosporins are now preferred treatments. Recently, XDR typhoid emerged in Pakistan, resistant even to third-generation cephalosporins. India also faces challenges, with sporadic cases initially declining but now re-emerging. New strains in India show resistance to third-generation cephalosporins due to plasmid acquisition from other bacteria, particularly blaCTX-M-carrying IncFIB(K). Due to the ongoing nature of this outbreak, the data from this study deserve further consideration in order to control its spread in India.
Catherine Krus, Ian Zander, Tyler J. Sherman
et al.
Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are two viruses belonging to the genus Orbivirus that are transmitted via insect vector, the Culicoides biting midge, causing disease in domestic and wild ruminants. These infections can lead to significant morbidity, mortality, and production losses in livestock, with economic consequences for cattle and sheep industries. Despite their growing impact due to environmental and anthropogenic changes, little is known of the prevalence of these viruses in North American bison (Bison bison). We present the first cross-sectional survey of BTV and EHDV in North American bison, with samples collected from 287 animals across 9 herds in 7 U.S. states from September to November 2023. Using competitive enzyme-linked immunosorbent assays (cELISA), we detected seroprevalence rates of 56.5% for BTV and 57.5% for EHDV. We found higher seroprevalence in North American bison compared to reports in European bison populations, suggesting that bison could potentially serve as incidental hosts of orbiviruses during key transmission periods; however, their role in virus transmission remains uncertain and warrants further investigation, particularly regarding the duration of viremia, potential amplification capacity, and year-to-year variability in PCR positivity. Logistic regression analysis revealed age as a significant predictor for both BTV (OR: 1.15, CI: 1.05–1.26, p: 0.006) and EHDV (OR: 1.16, CI: 1.06–1.28, p: 0.0014) seropositivity. PCR amplification identified circulating BTV serotypes 6, 11, 13, 17. Additionally, age was negatively associated with PCR positivity for both BTV (OR: 0.70, CI: 0.53–0.93, p: 0.014) and EHDV (OR: 0.56, CI: 0.33–0.93, p: 0.024), suggesting a decline in detectable viremia with increasing age. Although complex environmental and epidemiological factors likely play a role, this trend may be due to older animals having experienced more vector seasons, thereby increasing their cumulative exposure and subsequent immunity to these viruses over time. The significant age-associated dynamics reveal the importance of considering life stage in disease surveillance and management. Our study also highlights the importance of integrating bison into future vector-borne disease research and control strategies to mitigate risks to livestock, wildlife, and ecosystem health.
O. P. Yavorovskyi, A. V. Ragulya, V. M. Riabovol
et al.
The aim: to study the influence of structural, spectral and quantum-chemical parameters of the synthesized TiO2, TiO2/Ag (4 wt. %) and TiO2/Ag (8 wt. %) nanosystems on biological activity.
Materials and methods. The structural-morphological, spectral, toxicological and cytotoxic properties of TiO2 nanomaterials with silver content in the range from 0 wt % to 8 wt. % for the direction of human biosafety were investigated. The TiO2/Ag composites were characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and the results of high-level quantum chemical calculations.
Results. The optical activity of the TiO2/Ag composite was determined by Raman spectroscopy, which is confirmed by the shift in the Eg1 mode frequency from 143 cm-1 to 157 cm-1 and the FWHM in the range from 12 cm-1 to 19 cm-1 due to the decrease in the size of the TiO2 crystallites. The mode shift in nano-TiO2/Ag reflects a certain deformation of the anatase-modified titanium dioxide crystal lattice upon doping with silver. This leads to an increase in the ability to produce reactive oxygen species on the surface of the TiO2/Ag nanoparticle and to an increase in biological activity (4 wt. % Ag; 8 wt. % Ag) compared to undoped TiO2, providing an increase in their toxicity, which is confirmed by the values LD50, CC50 parameters, respectively. According to the results of quantum chemical calculations, it was established that during the adsorption of the Ag2 dimer on the surface of anatase in the Ti15O41H22Ag2 adsorption complex, two Ag atoms are involved with the formation of four Ag–O bonds, the length of which with the two-coordinated oxygen atoms of the TiO2 surface is 2.44 Å, and the Ag–Ag bond length increases to 2.75 Å, compared to the equilibrium distance in the diatomic Ag2 molecule (2.53 Å). This indicates the vibrationally excited state of the Ag2 diatomic fragment in the Ti15O41H22Ag2 adsorption complex. It should also be noted that the ionization potential of the adsorption complex decreased from 7.35 eV to 5.72 eV. The result of such changes is the increased reactivity of argentum atoms compared to their reactivity in the diatomic Ag2 molecule. Due to the fact that silver atoms adsorbed on the surface of anatase nanoparticles act as electron traps, the efficiency of separation of photogenerated electron-hole pairs (excitons) with interphase electron transfer increases, which increases the photocatalytic and biocidal properties of silver-doped anatase.
Conclusions. There is a certain objective relationship between the physicochemical parameters of nanoparticles and their biological activity, which can be characterized not only qualitatively, but also quantitatively. Thus, in the materials of our research, the influence of their size, specific surface area, the presence of hydroxyl groups on the surface of the nanoparticle, the size of crystallites, the size of interatomic bonds, and the ionization potential on the toxicity of nanoparticles has been demonstrated. These data are of great scientific importance not only in terms of their hygienic regulation, but also in terms of further synthesis of safer nanomaterials.
Farhan Kursheed, Asraar Tabassum, Umme Farwa
et al.
Background and Objectives: Antimicrobial resistance has emerged as a significant global health threat. Infections caused by Multi Drug-Resistant (MDR) bacteria pose formidable challenges in terms of treatment options and patient outcomes. Pus cultures serve as crucial diagnostic tools in identifying the agents responsible for various infections, and their antimicrobial susceptibility patterns which help in establishment of empirical therapy guidelines. This study was conducted to determine the pathogen and its susceptibility pattern from pus cultures and to generate antibiogram in our tertiary care setting.
Materials and Methods: It was a cross-sectional study, conducted for a period of six months, from July 2022 to December 2022, in the Pathology Department of Pakistan Institute of Medical Sciences (PIMS).
Results: Out of total 2507 samples received, 1242 (49.5%) showed positive culture. Among the 1242 positive samples, 364 were Gram positive cocci (GPCs) and 878 were Gram negative rods (GNRs). Methicillin resistant Staphylococcus aureus (MRSA) was the most common isolate (23%) followed by Klebsiella pneumoniae (22.6%), Pseudomonas aeruginosa (16.9%), Enterobacter spp. (15.5%) and Escherichia coli (14.2%). Vancomycin was found to be highly effective (100%) against MRSA. GPCs were highly susceptible to linezolid (98%) while GNRs showed high level of sensitivity to colistin (96%) and tigecycline (92%).
Conclusion: The generation of a local antibiogram specific to the hospital setting is essential to effectively manage infections empirically and preserve the efficacy of existing antibiotics. By implementing antimicrobial stewardship practices based on a better understanding of antibiotic susceptibility patterns, we can contribute to the mitigation of antibiotic resistance and improve patient outcomes.
ABSTRACT Zika virus (ZIKV) is an important pathogen that causes Guillain-Barre syndrome in adults and congenital Zika syndrome in newborns. Interferon (IFN) triggers intracellular antiviral signaling through two essential mediators STAT1 and STAT2, which are critical for host innate antiviral immunity. ZIKV has been reported to antagonize host IFN signaling by diverse mechanisms, including NS5-dependent and -independent ablation of STAT2. Whether flaviviruses target STAT1 remains controversial. In this study, we used infectious clones of ZIKV MR766 as tools and found that ZIKV infection triggered caspase-dependent cleavage of STAT1 during late infection. Further studies identified that the cleavage site is the aspartic acid 694, and the D694A mutation rendered STAT1 resistant to ZIKV infection-induced cleavage. Murine STAT1 (mSTAT1) was resistant to cleavage in ZIKV-infected cells. Ectopically expressed STAT1.D694A and mSTAT1 exerted comparable anti-ZIKV activity upon IFN treatment, challenging the role of STAT1 cleavage in IFN antagonism. We further knocked out STAT1 in the mouse embryonic fibroblast NIH3T3 cells, and STAT1 knockout dramatically augmented ZIKV infection, suggesting a STAT1-mediated viral restriction. Intriguingly, in the STAT1-knockout NIH3T3 cells, complementation of mSTAT1.D695G, a cleavage-sensitive variant, and the wild-type mSTAT1 both restored comparable anti-viral activities. These data suggest that caspase-mediated STAT1 cleavage is dispensable for IFN antagonism in ZIKV-infected cells. IMPORTANCE Zika virus (ZIKV) is a re-emerging flavivirus. Similar to other flaviviruses, ZIKV antagonizes the host interferon (IFN) signaling pathway to establish infection. Understanding the molecular mechanism by which ZIKV antagonizes IFN-induced antiviral signaling may lead to a new antiviral strategy by cracking the IFN antagonism. Flaviviruses have been reported to employ NS5-dependent and -independent mechanisms to block STAT2-mediated signaling, whereas whether flaviviruses target STAT1 remains controversial. Herein, we found that ZIKV infection triggered caspase-dependent cleavage of STAT1 at the aspartic acid 694 during late infection, whereas murine STAT1 (mSTAT1) was resistant to cleavage. Intriguingly, ectopically expressed cleavage-resistant human STAT1.D694A or complementation of cleavable mSTAT1.D695G exerted comparable anti-ZIKV activity with their counterparts, challenging the role of caspase-mediated STAT1 cleavage in the IFN antagonism in ZIKV-infected cells. These data may also imply a dominant role of the antagonism of STAT2 but not STAT1 in ZIKV-infected cells.
Muluneh Ademe, Yaneth Osorio, Rawliegh Howe
et al.
Ethiopia is among the countries with a high leishmaniasis burden. In this retrospective review, we aimed to determine hematological and clinical features associated with initial poor treatment outcomes of visceral leishmaniasis (VL) patients. The majority of VL cases in this study had leucopenia (94.3%), thrombocytopenia (87.1%), and anemia (85.9%). HIV coinfection was present in 7.0% (<i>n</i> = 23) of VL cases. At the center, VL patients without HIV coinfection were treated with sodium stibogluconate and paromomycin combination, whereas HIV coinfected cases were treated with AmBisome and miltefosine combination therapy. End-of-treatment cure rates among HIV-positive and HIV-negative visceral leishmaniasis cases, respectively, were 52.2% and 96.9%. Case fatality rates were 34.8% and 2.7% in HIV-positive and HIV-negative cases, respectively. Overall, non-survivors in this study were more likely to have HIV (55.0% vs. 4.1%, <i>p</i> < 0.001), sepsis (15.0% vs. 1.4%, <i>p</i> = 0.019), and dyspnea (40.0% vs. 2.7%, <i>p</i> < 0.001) at admission. In this regard, particular attention to the management of superimposed disease conditions at admission, including sepsis, HIV, and dyspnea, is needed to improve VL patients’ treatment outcomes. The inadequacy of the current treatments, i.e., AmBisome and miltefosine combination therapy, for HIV coinfected visceral leishmaniasis patients requires further attention as it calls for new treatment modalities.
Lucia Taramasso, Antonio Falletta, Elena Ricci
et al.
The aim of the present study was to evaluate CD4/CD8 dynamics in patients on dolutegravir (DTG)-based two-drug regimens (2DRs) and compare them with DTG-containing triple-drug regimens (3DRs). A prospective observational study was performed in the context of the SCOLTA cohort. Experienced PWH with HIV-RNA < 50 copies/mL were included if they were on the DTG-2DR, the DTG + tenofovir/emtricitabine (TDF/FTC) regimen, the DTG + tenofovir alafenamide (TAF)/FTC regimen, or the DTG + abacavir/lamivudine (ABC/3TC) regimen; they were followed-up for at least one year. A total of 533 PWH were enrolled, 120 in the DTG + 3TC group, 38 in the DTG + protease inhibitors (PI) group, 67 in the DTG + rilpivirine (RPV) group, 49 in the DTG + TDF/FTC group, 27 in the DTG + TAF/FTC group, and 232 in the DTG + ABC/3TC group. After one year, the CD4/CD8 ratio significantly increased in the PWH treated with DTG + 3TC (+0.08 ± 0.26), DTG + TDF/FTC (+0.1 ± 0.19), and DTG + ABC/3TC (+0.08 ± 0.25). At two years, the CD4/CD8 increase was confirmed for PWH on DTG + TDF/FTC (+0.16 ± 0.28) and DTG + ABC/3TC (+0.1 ± 0.3). In the SCOLTA cohort, PWH on 2DRs experienced a CD4/CD8 increase only in the DTG + 3TC group. Controlled studies with longer follow-up will clarify the long-term immunological and clinical impacts of DTG-2DR.
Aref Shariati, Shabnam Razavi, Ehsanollah Ghaznavi-Rad
et al.
Abstract Background and aim Recent studies have proposed that commensal bacteria might be involved in the development and progression of gastrointestinal disorders such as colorectal cancer (CRC). Therefore, in this study, the relative abundance of Fusobacterium nucleatum, Bacteroides fragilis, Streptococcus bovis/gallolyticus, and Enteropathogenic Escherichia coli (EPEC) in CRC tissues, and their association with clinicopathologic characteristics of CRC was investigated in Iranian patients. Moreover, the role of these bacteria in the CRC-associated mutations including PIK3CA, KRAS, and BRAF was studied. Method To these ends, the noted bacteria were quantified in paired tumors and normal tissue specimens of 30 CRC patients, by TaqMan quantitative Real-Time Polymerase Chain Reaction (qPCR). Next, possible correlations between clinicopathologic factors and mutations in PIK3CA, KRAS, and BRAF genes were analyzed. Results In studied samples, B. fragilis was the most abundant bacteria that was detected in 66 and 60% of paired tumor and normal samples, respectively. Furthermore, 15% of the B. fragilis-positive patients were infected with Enterotoxigenic B. fragilis (ETBF) in both adenocarcinoma and matched adjacent normal samples. F. nucleatum was also identified in 23% of tumors and 13% of adjacent normal tissue samples. Moreover, the relative abundance of these bacteria determined by 2-ΔCT was significantly higher in CRC samples than in adjacent normal mucosa (p < 0.05). On the other hand, our findings indicated that S. gallolyticus and EPEC, compared to adjacent normal mucosa, were not prevalent in CRC tissues. Finally, our results revealed a correlation between F. nucleatum-positive patients and the KRAS mutation (p = 0.02), while analyses did not show any association between bacteria and mutation in PIK3CA and BRAF genes. Conclusion The present study is the first report on the analysis of different bacteria in CRC tissue samples of Iranian patients. Our findings revealed that F. nucleatum and B. fragilis might be linked to CRC. However, any link between gut microbiome dysbiosis and CRC remains unknown.
Neoplasms. Tumors. Oncology. Including cancer and carcinogens, Infectious and parasitic diseases
Ali Maleka, Sadegh Khosravi, Abdorrahman Charkazi
et al.
Background and Objective: Diabetes is one of the most common chronic diseases and also the biggest health problem in all countries. The world health organization has called it a silent epidemic. Self-care is one of the most important factors in controlling blood sugar in diabetics’ patients. This study was done to determine the relationship between self-care and glycosylated hemoglobin level diabetic patients in rural area in Golestan Province, northern Iran.
Methods: This descriptive-analytical study was done on 239 male and female patients with type 2 diabetes (56.92±10.70 years) in rural area in Golestan Province, northern Iran during 2016. Data collection tool were a standard diabetes self-care questionnaire with demographic variables and HbA1C test. Completion of data and sampling was done by referring to the health center and calling patients.
Results: There was no significant relationship between glycemic controls with any of the self-care items studied. Mean of HbA1c was 8.23±1.85%. 97 patients (40.6%) had good blood sugar control (less than 7.5%). Patientchr('39')s self-care had a mean of 3.58, of which the highest score was related to the dietary regimen (6.60) and the lowest was related to self-monitoring of blood glucose (0.88) and regular physical activity (2.3).
Conclusion: Self-care of the patients was moderate. Interventions to increase self-care of patients are recommended in this area.
Extraction of Phylllantus amarus plant powder using hot percolation and cold percolation techniques revealed the presence of alkaloids, flavonoids, terpenoids, volatile oil, saponin, tannin, anthraquinone, cardiac glycosides, phenolic compounds, reducing and non- reducing sugars. The hot percolation crude extract also revealed higher scavenging activity compared with ascorbic acid (standard reference) and cold percolation crude extract. Pre-incubation of human urine with hot percolation and cold percolation crude extract of Phyllanthus amarus to determine its effect on crystallization process of crystal salts (calcium oxalate, calcium phosphate and cysteine) which causes nephrolithiasis (kidney stone) yielded excellent results on calcium phosphate (100% effective), calcium oxalate (97% and 85.67%) while cysteine (91% and 84.67%). A total of fifteen (15) flavonoid compounds identified in the hot and cold percolation extract of Phyllanthus amarus using gas chromatography analysis include flavan-3-ols, flavones, flavonols, flavanones and isoflavanones. High flavonoid content in the hot percolation crude extract was due to the presence of significant concentrations (mg/100ml) of quercetin (282.50), catechin (16.32), kaemferol (214.33), luteolin (51.79), apigenin (1.33), epicatechin (4.13), isorhamnetin (5.49), and rutin (11.72). The sensitivity pattern of Phyllanthus amarus leaf extract towards test organisms (Pseudomonas aeruginosa, Escherichia coli Proteus mirabilis and Klebsiella pneumonia) were determined using agar well diffusion technique. All test organisms were extremely sensitive to hot percolation extract of Phyllanthus amarus compared to cold percolation extract and antibiotics used as standard reference. Prevention of renal stone and urinary tract infection recurrence is a serious problem in human health but results obtained in this research shows that Phyllanthus amarus leaf is a good source of effective crude inhibitors for crystal formation which can be used in the treatment of kidney stone, urinary tract infection and other reactive oxygen species (ROS)-related disorders.
Keywords: Phyllanthus amarus, Flavonoid, Kidney stone, Escherichia coli
Multi-drug resistance (MDR) <em>Escherichia coli</em> have become a major threat due to their ability to overcome different types of antibiotics. However, Extended Spectrum β-lactamase <em>E. coli</em> (ESBLE) imposes an additional threat due to their ability to resist the 3<sup>rd</sup> generation cephalosporins. Accordingly, our study aimed to investigate the antibiogram profile of ESBLE isolates obtained from sheep. A Total of 40 ESBLE isolates were included in this study which represents sheep fecal and milk samples. Twelve antibiotics were selected to perform antibiotic sensitivity tests following standard microbiological methods. The results of the study showed that the highest resistance percentages were recorded for tetracycline 97.5%, ciprofloxacin 80%, trimethoprim/sulfamethoxazole 65%, and streptomycin 57.5%. While other antibiotics recorded lesser values. On the other hand, all isolates were susceptible to gentamycin and tobramycin each at 92.5%, followed by chloramphenicol and levofloxacin each at 82.5% and nitrofurantoin 72.5%. While fewer values of sensitivity were recorded for streptomycin, trimethoprim/sulfamethoxazole, azithromycin, nalidixic acid, ciprofloxacin and, tetracycline. The study concluded that ESBLE of sheep origin that have additional resistance features to other antibiotics could be a major threat for spreading resistance and contaminating the environment and finally impose negative impact for response to antibiotic treatment in humans.
Abstract Objective The major objective of the study was to sequence the whole genome of four Bangladeshi individuals and identify variants that are known to be associated with functional changes or disease states. We also carried out an ontology analysis to identify the functions and pathways most likely to be affected by these variants. Results We identified around 900,000 common variants and close to 5 million unique ones in all four of the individuals. This included over 11,500 variants that caused nonsynonymous changes in proteins. Heart function associated pathways were heavily implicated by the ontology analysis; corroborating previous studies that claimed the Bangladeshi population as highly susceptible to heart disorders. Two variants were found that have been previously identified as pathogenic factors in familial hypercholesteremia and structural disorders of the heart. Other pathogenic variants we found were associated with pseudoxanthoma elasticum, cancer progression, polyagglutinable erythrocyte syndrome, preeclampsia, and others.
Jessica L. Kevill, Andrea Highfield, Gideon J. Mordecai
et al.
Deformed wing virus (DWV) is one of the most prevalent honey bee viral pathogens in the world. Typical of many RNA viruses, DWV is a quasi-species, which is comprised of a large number of different variants, currently consisting of three master variants: Type A, B, and C. Little is known about the impact of each variant or combinations of variants upon the biology of individual hosts. Therefore, we have developed a new set of master variant-specific DWV primers and a set of standards that allow for the quantification of each of the master variants. Competitive reverse transcriptase polymerase chain reaction (RT-PCR) experimental design confirms that each new DWV primer set is specific to the retrospective master variant. The sensitivity of the ABC assay is dependent on whether DNA or RNA is used as the template and whether other master variants are present in the sample. Comparison of the overall proportions of each master variant within a sample of known diversity, as confirmed by next-generation sequence (NGS) data, validates the efficiency of the ABC assay. The ABC assay was used on archived material from a Devon overwintering colony loss (OCL) 2006–2007 study; further implicating DWV type A and, for the first time, possibly C in the untimely collapse of honey bee colonies. Moreover, in this study DWV type B was not associated with OCL. The use of the ABC assay will allow researchers to quickly and cost effectively pre-screen for the presence of DWV master variants in honey bees.
Katrin eHug, William A Maher, Matthew eStott
et al.
Acid-sulfide hot springs are analogs of early Earth geothermal systems where microbial metal(loid) resistance likely first evolved. Arsenic is a metalloid enriched in the acid-sulfide hot spring Champagne Pool (Waiotapu, New Zealand). Arsenic speciation in Champagne Pool follows reaction paths not yet fully understood with respect to biotic contributions and coupling to biogeochemical sulfur cycling. Here we present quantitative arsenic speciation from Champagne Pool, finding arsenite dominant in the pool, rim and outflow channel (55-75% total arsenic), and dithio- and trithioarsenates ubiquitously present as 18-25% total arsenic. In the outflow channel, dimethylmonothioarsenate comprised ≤9% total arsenic, while on the outflow terrace thioarsenates were present at 55% total arsenic. We also quantified sulfide, thiosulfate, sulfate and elemental sulfur, finding sulfide and sulfate as major species in the pool and outflow terrace, respectively. Elemental sulfur reached a maximum at the terrace. Phylogenetic analysis of 16S rRNA genes from metagenomic sequencing revealed the dominance of Sulfurihydrogenibium at all sites and an increased archaeal population at the rim and outflow channel. Several phylotypes were found closely related to known sulfur- and sulfide-oxidizers, as well as sulfur- and sulfate-reducers. Bioinformatic analysis revealed genes underpinning sulfur redox transformations, consistent with sulfur speciation data, and illustrating a microbial role in sulfur-dependent transformation of arsenite to thioarsenate. Metagenomic analysis also revealed genes encoding for arsenate reductase at all sites, reflecting the ubiquity of thioarsenate and a need for microbial arsenate resistance despite anoxic conditions. Absence of the arsenite oxidase gene, aio, at all sites suggests prioritization of arsenite detoxification over coupling to energy conservation. Finally, detection of methyl arsenic in the outflow channel, in conjunction with increased se