In women with uncomplicated UTIs, gepotidacin was noninferior to nitrofurantoin for therapeutic response at 10 to 13 d.

SOURCE CITATION: Wagenlehner F, Perry CR, Hooton TM, et al. Oral gepotidacin versus nitrofurantoin in patients with uncomplicated urinary tract infection (EAGLE-2 and EAGLE-3): two randomised, controlled, double-blind, double-dummy, phase 3, non-inferiority trials. Lancet. 2024;403:741-755. 38342126.

Improving nitrofurantoin resistance prediction in Escherichia coli from whole-genome sequence by integrating NfsA/B enzyme assays.

Nitrofurantoin resistance in Escherichia coli is primarily caused by mutations damaging two enzymes, NfsA and NfsB. Studies based on small isolate collections with defined nitrofurantoin MICs have found significant random genetic drift in nfsA and nfsB, making it extremely difficult to predict nitrofurantoin resistance from whole-genome sequence (WGS) where both genes are not obviously disrupted by nonsense or frameshift mutations or insertional inactivation. Here, we report a WGS survey of 200 oqxAB-negative E. coli from community urine samples, of which 34 were nitrofurantoin resistant. We characterized individual non-synonymous mutations seen in nfsA and nfsB among this collection using complementation cloning and NfsA/B enzyme assays in cell extracts. We definitively identified R203C, H11Y, W212R, A112E, and A112T in NfsA and R121C, Q142H, F84S, P163H, W46R, K57E, and V191G in NfsB as amino acid substitutions that reduce enzyme activity sufficiently to cause resistance. In contrast, E58D, I117T, K141E, L157F, A172S, G187D, and A188V in NfsA and G66D, M75I, V93A, and A174E in NfsB are functionally silent in this context. We identified that 9/166 (5.4%) nitrofurantoin-susceptible isolates were "pre-resistant," defined as having loss of function mutations in nfsA or nfsB. Finally, using NfsA/B enzyme assays and proteomics, we demonstrated that 9/34 (26.5%) ribE wild-type nitrofurantoin-resistant isolates also carried functionally wild-type nfsB or nfsB/nfsA. In these cases, NfsA/B activity was reduced through downregulated gene expression. Our biological understanding of nitrofurantoin resistance is greatly improved by this analysis but is still insufficient to allow its reliable prediction from WGS data.

Nitrofurantoin for the treatment of uncomplicated urinary tract infection in female patients: the impact of dosing regimen, age, and renal function on drug exposure.

PURPOSE: The aim of this study is to determine nitrofurantoin exposure in female patients with different age and renal function with complaints of an uncomplicated UTI. Also the nitrofurantoin exposure in relation to the dosage regimen will be studied. METHODS: Eight general practitioners (GP) participated in the study and included 38 patients with symptoms of an uncomplicated UTI, treated either with a dose of 50 mg q6h or 100 mg q12h, upon the discretion of the GP. Nitrofurantoin exposure was quantified in the patient's 24-h urine samples by UHPLC-UV and the area under the curve was calculated. RESULTS: The 38 patients provided a range of 2-17 urine samples. The urine nitrofurantoin exposure was 1028 mg h/L for the patients receiving 50 mg q6h and 1036 mg h/L for those treated with 100 mg q12h (p = 0.97) and was not affected by age and eGFR (p = 0.64 and p = 0.34, respectively). CONCLUSION: The data obtained do not support the discouragement of nitrofurantoin use in the elderly and in patients with impaired renal function. Since only a small number of patients were included, a larger study with more patients is warranted to evaluate nitrofurantoin exposure and adverse effects.

Whole genome sequencing identifies genetic variants associated with co-trimoxazole hypersensitivity in Asians.

BACKGROUND: Co-trimoxazole, a sulfonamide antibiotic, is used to treat a variety of infections worldwide, and it remains a common first-line medicine for prophylaxis against Pneumocystis jiroveci pneumonia. However, it can cause severe cutaneous adverse reaction (SCAR), including Stevens-Johnson syndrome, toxic epidermal necrolysis, and drug reaction with eosinophilia and systemic symptoms. The pathomechanism of co-trimoxazole-induced SCAR remains unclear. OBJECTIVE: We aimed to investigate the genetic predisposition of co-trimoxazole-induced SCAR. METHODS: We conducted a multicountry case-control association study that included 151 patients with of co-trimoxazole-induced SCAR and 4631 population controls from Taiwan, Thailand, and Malaysia, as well as 138 tolerant controls from Taiwan. Whole-genome sequencing was performed for the patients and population controls from Taiwan; it further validated the results from Thailand and Malaysia. RESULTS: The whole-genome sequencing study (43 case patients vs 507 controls) discovered that the single-nucleotide polymorphism rs41554616, which is located between the HLA-B and MICA loci, had the strongest association with co-trimoxazole-induced SCAR (P = 8.2 × 10-9; odds ratio [OR] = 7.7). There were weak associations of variants in co-trimoxazole-related metabolizing enzymes (CYP2D6, GSTP1, GCLC, N-acetyltransferase [NAT2], and CYP2C8). A replication study using HLA genotyping revealed that HLA-B∗13:01 was strongly associated with co-trimoxazole-induced SCAR (the combined sample comprised 91 case patients vs 2545 controls [P = 7.2 × 10-21; OR = 8.7]). A strong HLA association was also observed in the case patients from Thailand (P = 3.2 × 10-5; OR = 3.6) and Malaysia (P = .002; OR = 12.8), respectively. A meta-analysis and phenotype stratification study further indicated a strong association between HLA-B∗13:01 and co-trimoxazole-induced drug reaction with eosinophilia and systemic symptoms (P = 4.2 × 10-23; OR = 40.1). CONCLUSION: This study identified HLA-B∗13:01 as an important genetic factor associated with co-trimoxazole-induced SCAR in Asians.

Adverse effects of chronic nitrofurantoin therapy in women with recurrent urinary tract infections in an outpatient setting.

PURPOSE: To review the frequency of adverse events reported with nitrofurantoin (NF) in perimenopausal and menopausal women on prolonged daily prophylaxis in an outpatient setting. METHODS: Electronic medical records of women aged 50-95 prescribed NF by 2 primary urology providers for at least 3 consecutive months from 2006 to 2018 were retrospectively reviewed. Demographics, reason for the initiation, dose and duration of therapy, explanation of therapy interruptions, occurrence of adverse events, comorbid conditions, and relevant lab and imaging results were recorded. The number of months on prolonged therapy were summed. RESULTS: Of the 221 patients included, 167 (77%) were prescribed 100 mg of NF daily with a mean duration of therapy of 1.5 years. The most common indication for therapy was recurrent urinary tract infection prophylaxis. Breakthrough urinary tract infections developed in 88 (40%) patients on prolonged NF therapy but only 10 were not restarted on NF. Four patients (1.8%) were determined to have pulmonary adverse events and 1 (0.4%) developed elevated liver function tests. CONCLUSION: In peri-menopausal and menopausal women, the risks and benefits of chronic NF therapy should be weighed by the clinician and patient prior to prescribing long term NF. Patients must be educated about the potential NF toxicities and clinically monitored for signs and symptoms of potential adverse events while on chronic NF therapy.

Safety and efficacy evaluation of low-dose trimethoprim-sulfamethoxazole for prophylaxis of Pneumocystis pneumonia in HIV uninfected patients undergoing hemodialysis: a retrospective observational study.

BACKGROUND: Pneumocystis pneumonia (PCP) is a potentially life-threatening infection. Trimethoprim-sulfamethoxazole (TMP-SMX) is considered as the first regimen for PCP prophylaxis according to several guidelines. The recommended prophylactic dose of TMP-SMX has been determined based on patients with normal renal function, but the appropriate dosage for patients undergoing hemodialysis is unknown. The aim of this study was to investigate the efficacy and safety of low-dose TMP-SMX in patients undergoing hemodialysis. METHODS: HIV-uninfected adult patients who were undergoing hemodialysis and administered TMP-SMX for PCP prophylaxis, were included, and divided into standard-dose (≥6 single strength (SS, TMP-SMX 80 mg/400 mg tablets/week) and low-dose groups (< 6 SS tablets/week). The endpoints were cumulative incidence of PCP and cumulative discontinuation rate of TMP-SMX due to adverse events. For comparison of the groups, we employed the chi-squared test for categorical variables and the Mann-Whitney U test for continuous variables. Risk factors for the endpoints were evaluated using the Cox Fine and Gray method. RESULTS: The median age of the 81 patients included in the study was 67 years (IQR: 60-76 years), and 52 patients (64.2%) were men. No patients in either group developed PCP during the observation period. The yearly cumulative incidence of discontinuation was 12.1% (95% confidence interval [CI]: 0.027-0.29) in the low-dose group and 35.6% (95% CI: 0.20-0.52) in the standard-dose group (P = 0.019). The adjusted hazard ratio of the low-dose group compared to standard-dose group was 0.18 (95% CI: 0.04-0.86, P = 0.032). CONCLUSIONS: None of the study patients developed PCP, and the cumulative discontinuation rate of TMP-SMX due to adverse events was significantly lower in the low-dose group compared to that in the standard-dose group (P = 0.032). These results indicate that low-dose TMP-SMX is an appropriate regimen to maintain a balance between PCP prophylaxis and prevention of adverse events due to TMP-SMX administration. These findings can guide health care professionals to determine TMP-SMX dosage when considering PCP prophylaxis for patients undergoing hemodialysis.

The Significance of Age and Causative Bacterial Morphology in the Choice of an Antimicrobial Agent to Treat Acute Uncomplicated Cystitis.

Differentiating patients by age and causative bacterial morphology might aid in making the appropriate choice of antimicrobial agent when treating acute uncomplicated cystitis. In this retrospective analysis, the non-susceptibility rates of the causative bacteria to cefcapene-pivoxil (CFPN-PI) and levofloxacin (LVFX) were determined after dividing patients with acute uncomplicated cystitis by age group (15-54 and 55-74 years old) and by bacterial morphology: gram-positive cocci (GPC) or gram-negative rod (GNR). The overall non-susceptibility rates for CFPN-PI and LVFX were 19.4% and 15.3%, respectively. When the subjects were divided by age, only the non-susceptibility rate for LVFX in the younger group significantly decreased (to 8.7%). When the groups were divided by both age and bacterial morphology, the younger GNR group had non-susceptibility rates of 6.9% to CFPN-PI and 7.8% to LVFX, whereas the younger GPC group showed 10.2% non-susceptibility to LVFX. The older GNR group showed 9.8% non-susceptibility to CFPN-PI, while the older GPC group showed 7.2% non-susceptibility to LVFX. All the non-susceptibility rates were lower than 10.2% in the sub-divided groups. Differentiating patients by age and the morphology of causative bacteria can aid in making the appropriate choice of antimicrobial agent and may improve treatment outcomes in patients with acute uncomplicated cystitis.

Validating an empiric sulfadiazine-trimethoprim dosage regimen for treatment of Escherichia coli and Staphylococcus delphini infections in mink (Neovison vison).

Antimicrobial agents are used extensively off-label in mink, as almost no agents are registered for this animal species. Pharmacokinetic (PK) and pharmacodynamic (PD) data are required to determine antimicrobial dosages specifically targeting mink bacterial pathogens. The aims of this study were to assess, in a PKPD framework, the empirical dosage regimen for a combination of trimethoprim (TMP) and sulfadiazine (SDZ) in mink, and secondarily to produce data for future setting of clinical breakpoints. TMP and SDZ PK parameters were obtained experimentally in 22 minks following IV or oral administration of TMP/SDZ (30 mg/kg, i.e. 5 mg/kg TMP and 25 mg/kg SDZ). fAUC/MIC with a target value of 24 hr was selected as the PKPD index predictive of TMP/SDZ efficacy. Using a modeling approach, PKPD cutoffs for TMP and SDZ were determined as 0.062 and 16 mg/L, respectively. By incorporating an anticipated potentiation effect of SDZ on TMP against Escherichia coli and Staphylococcus delphini, the PKPD cutoff of TMP was revised to 0.312 mg/L, which is above the tentative epidemiological cutoffs (TECOFF) for these species. The current empirical TMP/SDZ dosage regimen (30 mg/kg, PO, once daily) therefore appears adequate for treatment of wild-type E. coli and S. delphini infections in mink.

Pigeon Pea Husk for Removal of Emerging Contaminants Trimethoprim and Atenolol from Water.

The pace of industrialization and rapid population growth in countries such as India entail an increased input of industrial and sanitary organic micropollutants, the so-called emerging contaminants (EC), into the environment. The emission of EC, such as pharmaceuticals, reaching Indian water bodies causes a detrimental effect on aquatic life and ultimately on human health. However, the financial burden of expanding sophisticated water treatment capacities renders complementary, cost-efficient alternatives, such as adsorption, attractive. Here we show the merits of washed and milled pigeon pea husk (PPH) as low-cost adsorbent for the removal of the EC trimethoprim (TMP) and atenolol (ATN) that are among the most detected pharmaceuticals in Indian waters. We found a linear increase in adsorption capacity of PPH for TMP and ATN at concentrations ranging from 10 to 200 µg/L and from 50 to 400 µg/L, respectively, reflecting the concentrations occurring in Indian water bodies. Investigation of adsorption kinetics using the external mass transfer model (EMTM) revealed that film diffusion resistance governed the adsorption process of TMP or ATN onto PPH. Moreover, analysis of the adsorption performance of PPH across an extensive range of pH and temperature illustrated that the highest adsorption loadings achieved concurred with actual conditions of Indian waters. We anticipate our work as starting point towards the development of a feasible adsorbent system aiming at low-cost water treatment.

Drug-Drug Binary Solids of Nitrofurantoin and Trimethoprim: Crystal Engineering and Pharmaceutical Properties.

With the aim of developing multidrug solids through a tuned crystal engineering approach, we have selected two antiurinary infective drugs, namely, nitrofurantoin (NF) and trimethoprim (TMP) and isolated eight binary drug-drug solid solvates along with a nonsolvated cocrystal. Crystal structure analyses were performed for eight of these solids and rationalized in terms of known supramolecular synthons formed by pyrimidine, imide, and amine functionalities. Notably, the TMP-NF anhydrous cocrystal and its ionic cocrystal hydrate exhibit enhanced equilibrium solubilities compared to pure NF or the simple NF hydrate. Furthermore, the ionic cocrystal hydrate exhibits greater antibacterial activity against the Gram-negative bacteria, E. coli, compared to the parent TMP and NF at the lowest concentration of 3.9 µg/mL. This study indicates initial pathways using the cocrystal methodology that would help to eventually arrive at an antiurinary cocrystal with optimal properties.

High-throughput identification and rational design of synergistic small-molecule pairs for combating and bypassing antibiotic resistance.

Antibiotic-resistant infections kill approximately 23,000 people and cost $20,000,000,000 each year in the United States alone despite the widespread use of small-molecule antimicrobial combination therapy. Antibiotic combinations typically have an additive effect: the efficacy of the combination matches the sum of the efficacies of each antibiotic when used alone. Small molecules can also act synergistically when the efficacy of the combination is greater than the additive efficacy. However, synergistic combinations are rare and have been historically difficult to identify. High-throughput identification of synergistic pairs is limited by the scale of potential combinations: a modest collection of 1,000 small molecules involves 1 million pairwise combinations. Here, we describe a high-throughput method for rapid identification of synergistic small-molecule pairs, the overlap2 method (O2M). O2M extracts patterns from chemical-genetic datasets, which are created when a collection of mutants is grown in the presence of hundreds of different small molecules, producing a precise set of phenotypes induced by each small molecule across the mutant set. The identification of mutants that show the same phenotype when treated with known synergistic molecules allows us to pinpoint additional molecule combinations that also act synergistically. As a proof of concept, we focus on combinations with the antibiotics trimethoprim and sulfamethizole, which had been standard treatment against urinary tract infections until widespread resistance decreased efficacy. Using O2M, we screened a library of 2,000 small molecules and identified several that synergize with the antibiotic trimethoprim and/or sulfamethizole. The most potent of these synergistic interactions is with the antiviral drug azidothymidine (AZT). We then demonstrate that understanding the molecular mechanism underlying small-molecule synergistic interactions allows the rational design of additional combinations that bypass drug resistance. Trimethoprim and sulfamethizole are both folate biosynthesis inhibitors. We find that this activity disrupts nucleotide homeostasis, which blocks DNA replication in the presence of AZT. Building on these data, we show that other small molecules that disrupt nucleotide homeostasis through other mechanisms (hydroxyurea and floxuridine) also act synergistically with AZT. These novel combinations inhibit the growth and virulence of trimethoprim-resistant clinical Escherichia coli and Klebsiella pneumoniae isolates, suggesting that they may be able to be rapidly advanced into clinical use. In sum, we present a generalizable method to screen for novel synergistic combinations, to identify particular mechanisms resulting in synergy, and to use the mechanistic knowledge to rationally design new combinations that bypass drug resistance.

Spontaneous community-acquired PVL-producing Staphylococcus aureus mediastinitis in an immunocompetent adult - a case report.

BACKGROUND: Mediastinitis caused by hematogenous spread of an infection is rare. We report the first known case of community-acquired mediastinitis from hematogenous origin in an immunocompetent adult. This rare invasive infection was due to Panton-Valentine Leucocidin-producing (PVL+) methicillin-susceptible Staphylococcus aureus (MSSA). CASE PRESENTATION: A 22-year-old obese man without other medical history was hospitalized for febrile precordial chest pain. He reported a cutaneous back abscess 3 weeks before. CT-scan was consistent with mediastinitis and blood cultures grew for a PVL+ MSSA. Intravenous clindamycin (600 mg t.i.d) and cloxacillin (2 g q.i.d.), secondary changed for fosfomycin (4 g q.i.d.) because of a related toxidermia, was administered. Surgical drainage was performed and confirmed the presence of a mediastinal abscess associated with a fistula between the mediastinum and right pleural space. All local bacteriological samples also grew for PVL+ MSSA. In addition to clindamycin, intravenous fosfomycin was switched to trimethoprim-sulfamethoxazole after 4 weeks for a total of 10 weeks of antibiotics. CONCLUSIONS: We present the first community-acquired mediastinitis of hematogenous origin with PVL+ MSSA. Clinical evolution was favorable after surgical drainage and 10 weeks of antibiotics. The specific virulence of MSSA PVL+ strains played presumably a key role in this rare invasive clinical presentation.

Effectiveness of Methenamine for UTI Prevention in Older Adults.

Background: Methenamine is a drug used for the prevention of lower urinary tract infections (UTIs). However, efficacy has not been established in older adults or patients with varying degrees of kidney function. Objective: To evaluate the effectiveness of methenamine for the prevention of UTI in adults 60 years and older. Methods: This was a retrospective, pre-post, observational study. The study included primary care patients 60 years and older who were taking methenamine between January 1, 2015, and September 30, 2018. The primary outcome was the time to first UTI after methenamine initiation compared with the average time between UTIs in the 12 months prior to methenamine initiation. Results: Of 434 patients reviewed, 150 met inclusion criteria. The average time to UTI was 3.3 months prior to methenamine initiation compared with 5.5 months after methenamine initiation (P = 0.0004). There were 33 patients (22%) who did not have a UTI after methenamine initiation. Also, 14 patients (9.3%) had a calculated CrCl <30 mL/min at baseline. The average time to UTI in these patients was 3.3 months prior to methenamine initiation compared with 12.7 months after initiation (P < 0.0001). Conclusion and Relevance: Methenamine use was associated with a longer time to UTI in older adults with varying degrees of kidney function. The effectiveness of methenamine appeared to be similar regardless of kidney function, which is new evidence. Because of a lack of acquired resistance, methenamine may be an effective option for UTI prophylaxis in older adults.

Cost-effectiveness of prophylactic antibiotic use to prevent catheter-associated urinary tract infections.

PURPOSE: We evaluate the cost-effectiveness of prophylactic antibiotic use to prevent catheter-associated urinary tract infections. MATERIALS AND METHODS: A decision tree model was used to assess the cost-effectiveness of prophylactic antibiotics in preventing catheter-associated urinary tract infections for patients with a short-term indwelling urinary catheter. The model accounted for incidence of urinary tract infections with and without the use of prophylactic antibiotics, incidence of antibiotic-resistant urinary tract infections, as well as costs associated with diagnosis and treatment of urinary tract infections and antibiotic-resistant urinary tract infections. Costs were calculated from the health care system's perspective. We conducted one-way sensitivity analyses. RESULTS: The base case analysis showed that the use of prophylactic antibiotics is cost-saving in preventing catheter-associated urinary tract infections. The use of prophylactic antibiotics resulted in lower costs and higher quality-adjusted life-years compared with no prophylactic antibiotics. Sensitivity analyses showed that the optimal strategy changes to no prophylactic antibiotics when the incidence of urinary tract infections after prophylactic antibiotics exceeds 22% or the incidence of developing urinary tract infections without prophylactic antibiotics is less than 12%. Varying the costs of prophylactic antibiotics, urinary tract infection treatment, or antibiotic-resistant urinary tract infection treatment within a reasonable range did not change the optimal strategy. CONCLUSIONS: Prophylactic antibiotic use to prevent catheter-associated urinary tract infections is cost-effective under most conditions. These results were sensitive to the likelihood of developing catheter-associated urinary tract infections with and without prophylactic antibiotics. Our results are limited to the cost-effectiveness perspective on this clinical practice.

Reversible lung fibrosis in a 6-year-old girl after long term nitrofurantoin treatment.

BACKGROUND: Pulmonary side effects are well known, including lung fibrosis, in elderly patients treated with long-term nitrofurantoin to prevent urinary tract infections and secondary renal injury. However, pulmonary side effects have only been reported rarely in paediatric cases, despite nitrofurantoin being a first line prophylactic treatment of recurrent childhood urinary tract infection. CASE PRESENTATIONS: A 6-year-old girl was admitted to the hospital with dyspnea, general fatigue, loss of appetite and need for nasal oxygen treatment after long-term nitrofurantoin treatment. A computed tomography scan of the chest showed lung fibrosis. A biopsy confirmed this diagnosis. We suspected the fibrosis to be caused by the nitrofurantoin treatment. Thorough examinations reveal no other explanations. Nitrofurantoin was discontinued and the girl was treated with methylprednisolone. After 17 month a new scan and lung function test showed total regression of the lung fibrosis. CONCLUSIONS: This case underlines that risk of severe side effects should be taken in to account before initiation of long-term nitrofurantoin treatment in children.

Immunotherapy to reduce frequency of urinary tract infections in people with neurogenic bladder dysfunction; a pilot randomised, placebo-controlled trial.

OBJECTIVE: To establish the feasibility of a randomized, placebo-controlled trial to investigate the effect of a specific immunotherapy bacterial lysate OM-89 (Uro-Vaxom®) in reducing the frequency of urinary tract infections in people with neurogenic bladder dysfunction. DESIGN: A parallel-group, double-blind, randomized, placebo-controlled trial. SETTING: Patients at home, recruited through out-patient contact, social media and patient support groups. SUBJECTS: People with a spinal cord injury, multiple sclerosis, transverse myelitis or cauda equina syndrome who had suffered three or more clinically diagnosed urinary tract infections treated with antibiotics over the preceding 12 months. INTERVENTIONS: All participants took one capsule of oral OM-89 immunotherapy (6 mg) or matching Placebo (randomisation ratio 1:1), once daily in the morning for 3 months. MAIN MEASURES: The primary outcome was occurrence of a symptomatic urinary tract infection treated with an antibiotic, assessed at 3 and 6 months. Feasibility measures included recruitment, retention and practical difficulties. RESULTS: Of 115 patients screened, 49 were recruited, one withdrew before randomization, and 23 were allocated to the control group receiving matching placebo. Six participants, all in the control group, discontinued the intervention; all participants provided full data at both follow-up times. Over 6 months, 18/25 active group patients had 55 infections, and 18/23 control group patients had 47 infections. Most research and clinical procedures were practical, and acceptable to participants. CONCLUSION: It is feasible to undertake a larger trial. We recommend broader inclusion criteria to increase eligibility and generalizability.

Optimizing dosing of nitrofurantoin from a PK/PD point of view: What do we need to know?

Nitrofurantoin is an old antibiotic and an important first-line oral antibiotic for the treatment of uncomplicated urinary tract infections. However despite its long term use for over 60 years, little information is available with respect to its dose justification and this may be the reason of highly variable recommended doses and dosing schedules. Furthermore, nitrofurantoin is not a uniform product -crystal sizes of nitrofurantoin, and therefore pharmacokinetic properties, differ significantly by product. Moreover, pharmacokinetic profiling of some products is even lacking, or difficult to interpret because of its unstable chemical properties. Pharmacokinetic and pharmacodynamic data is now slowly becoming available. This review provides an overview of nitrofurantoins antibacterial, pharmacokinetic and pharmacodynamic properties. This shows that a clear rationale of current dosing regimens is scanty.

Maladaptive DNA repair is the ultimate contributor to the death of trimethoprim-treated cells under aerobic and anaerobic conditions.

The bactericidal effects of antibiotics are undoubtedly triggered by target-specific interactions, but there is growing evidence that an important aspect of cytotoxicity results from treatment-induced metabolic perturbations. In this study, we characterized molecular mechanisms whereby trimethoprim treatment results in cell death, using Escherichia coli as the model organism. E. coli cells grown in rich medium that contained all amino acids and low amounts of thymidine were treated with trimethoprim under aerobic and anaerobic conditions. Under these growth conditions, accelerated thymine depletion is the primary trigger of the processes leading to cell death. Thymine depletion-induced DNA replication stress leads to the production of reactive oxygen species under aerobic conditions and of the DNA-damaging byproducts of nitrate respiration under anaerobic conditions. Lowering the DNA replication initiation rate by introducing the dnaA(Sx) allele or by overexpressing Hda protein reduces the number of active replication forks, which reduces the consumption of thymidine and increases resistance to trimethoprim under both aerobic and anaerobic conditions. Analysis of the involvement of DNA repair enzymes in trimethoprim-induced cytotoxicity clearly indicates that different amounts and/or different types of DNA lesions are produced in the presence or absence of oxygen. Maladaptive processing of the DNA damage by DNA repair enzymes, in particular by MutM and MutY DNA glycosylases, ultimately contributes to cell death.

Legionella pneumonia: increased risk after COVID-19 lockdown? Italy, May to June 2020.

We report a case of Legionella pneumonia in a dishwasher of a restaurant in Rome, Italy, just after the end of the lockdown that was in place to control the SARS-CoV-2 epidemic. The case highlights the importance of strict monitoring of water and air systems immediately before reopening business or public sector buildings, and the need to consider Legionella infections among the differential diagnosis of respiratory infections after lockdown due to the ongoing COVID-19 pandemic.

Indirect Photodegradation of Sulfamethoxazole and Trimethoprim by Hydroxyl Radicals in Aquatic Environment: Mechanisms, Transformation Products and Eco-Toxicity Evaluation.

The bacteriostatic antibiotics, sulfamethoxazole (SMX) and trimethoprim (TMP), have frequently been found in wastewater and surface water, which raises the concerns about their ecotoxicological effects. The indirect photochemical transformation has been proven to be an efficient way to degrade SMX and TMP. In this study, the reaction mechanisms of the degradation by SMX and TMF by OH radicals were investigated by theoretical calculations. Corresponding rate constants were determined and the eco-toxicity of SMX and TMP and its degradations products were predicted using theoretical models. The results indicate that the most favorable pathways for the transformation of SMX and TMP are both •OH-addition reaction of benzene ring site with lowest Gibbs free energy barriers (6.86 and 6.21 kcal mol-1). It was found that the overall reaction rate constants of •OH-initial reaction of SMX and TMP are 1.28 × 108 M-1 s-1 and 6.21 × 108 M-1 s-1 at 298 K, respectively. When comparing the eco-toxicity of transformation products with parent SMX and TMP, it can be concluded that the acute and chronic toxicities of the degraded products are reduced, but some products remain harmful for organisms, especially for daphnid (toxic or very toxic level). This study can give greater insight into the degradation of SMX and TMP by •OH through theoretical calculations in aquatic environment.