In vitro antitrypanosomal activity of synthesized nitrofurantoin-triazole hybrids against Trypanosoma species causing animal African trypanosomosis

Animal African trypanosomosis (AAT) is a disease caused by Trypanosoma brucei brucei, T. vivax, T. evansi and T. congolense which are mainly transmitted by tsetse flies (maybe the family/genus scientific name for the tsetse flies here?). Synthetic trypanocidal drugs are used to control AAT but have reduced efficacy due to emergence of drug resistant trypanosomes. Therefore, there is a need for the continued development of new safe and effective drugs. The aim of this study was to evaluate the in vitro anti-trypanosomal activity of novel nitrofurantoin compounds against trypanosomes (Trypanosoma brucei brucei, T. evansi and T. congolense) causing AAT. This study assessed previously synthesized nineteen nitrofurantoin-triazole (NFT-TZ) hybrids against animal trypanosomes and evaluated their cytotoxicity using Madin-Darby bovine kidney cells. The n-alkyl sub-series hybrids, 8 (IC50 0.09 ± 0.02 μM; SI 686.45) and 9 (IC50 0.07 ± 0.04 μM; SI 849.31) had the highest anti-trypanosomal activity against T. b. brucei. On the contrary, the nonyl 6 (IC50 0.12 ± 0.06 μM; SI 504.57) and nitrobenzyl 18 (IC50 0.11 ± 0.03 μM; SI 211.07) displayed the highest trypanocidal activity against T. evansi. The nonyl hybrid 6 (IC50 0.02 ± 0.01 μM; SI 6328.76) was also detected alongside the undecyl 8 (IC50 0.02 ± 0.01 μM; SI 3454.36) and 3-bromobenzyl 19 (IC50 0.02 ± 0.01 μM; SI 2360.41) as the most potent hybrids against T. congolense. These hybrids had weak toxicity effects on the mammalian cells and highly selective submicromolar antiparasitic action efficacy directed towards the trypanosomes, hence they can be regarded as potential trypanocidal leads for further in vivo investigation.

Bacteriological profile, antimicrobial susceptibility, and factors associated with urinary tract infection in pregnant women

INTRODUCTION

Urinary tract infection (UTI) is a common bacterial complication in pregnancy. The study aimed to estimate the prevalence, risk factors, and bacterial etiology of UTI during pregnancy and determine the efficacy of antimicrobial drugs in treating UTIs.

METHODOLOGY

Urine specimens and clinical data were collected from pregnant women who attended primary health centers in Erbil, Iraq. All specimens were cultured on appropriate media and identified by standard microbiological methods. The pregnant women were grouped into symptomatic UTI group, asymptomatic bacteriuria group, and the control group. The agar dilution method was used to determine antimicrobial susceptibility.

RESULTS

Among the 5,042 pregnant women included in this study, significant bacteriuria was found in 625 (12.40%) of the cases, and 198 (31.68%) had symptomatic UTI, of which 43.59% were diagnosed during the third trimester. Out of the 643 bacteria isolated, 33.28% were symptomatic UTI, of which 43.59% developed during the third trimester. There was a significant difference in the bacterial etiology between symptomatic UTI and asymptomatic bacteriuria (p = 0.002), as well as between cystitis and pyelonephritis (p = 0.017). The most common bacterial species isolated was Escherichia coli, which was susceptible to fosfomycin (100%), meropenem (99.45%), and nitrofurantoin (97.8%).

CONCLUSIONS

Pregnant women are more likely to develop UTI in the third trimester. Escherichia coli is the predominant pathogen. The study suggests the use of fosfomycin, meropenem, and nitrofurantoin for the treatment of UTI. No Gram-positive isolates were resistant to daptomycin.

Prevalence, regional distribution, and trends of antimicrobial resistance among female outpatients with urine Klebsiella spp. isolates: a multicenter evaluation in the United States between 2011 and 2019

BACKGROUND

Antimicrobial resistance research in uncomplicated urinary tract infection typically focuses on the main causative pathogen, Escherichia coli; however, little is known about the antimicrobial resistance burden of Klebsiella species, which can also cause uncomplicated urinary tract infections. This retrospective cohort study assessed the prevalence and geographic distribution of antimicrobial resistance among Klebsiella species and antimicrobial resistance trends for K. pneumoniae in the United States (2011-2019).

METHODS

K. pneumoniae and K. oxytoca urine isolates (30-day, non-duplicate) among female outpatients (aged ≥ 12 years) with presumed uUTI at 304 centers in the United States were classified by resistance phenotype(s): not susceptible to nitrofurantoin, trimethoprim/sulfamethoxazole, or fluoroquinolone, extended-spectrum β-lactamase-positive/not susceptible; and multidrug-resistant based on ≥ 2 and ≥ 3 resistance phenotypes. Antimicrobial resistance prevalence by census division and age, as well as antimicrobial resistance trends over time for Klebsiella species, were assessed using generalized estimating equations.

RESULTS

270,552 Klebsiella species isolates were evaluated (250,719 K. pneumoniae; 19,833 K. oxytoca). The most frequent resistance phenotypes in 2019 were nitrofurantoin not susceptible (Klebsiella species: 54.0%; K. pneumoniae: 57.3%; K. oxytoca: 15.1%) and trimethoprim/sulfamethoxazole not susceptible (Klebsiella species: 10.4%; K. pneumoniae: 10.6%; K. oxytoca: 8.6%). Extended-spectrum β-lactamase-positive/not susceptible prevalence was 5.4%, 5.3%, and 6.8%, respectively. K. pneumoniae resistance phenotype prevalence varied (p < 0.0001) geographically and by age, and increased over time (except for the nitrofurantoin not susceptible phenotype, which was stable and > 50% throughout).

CONCLUSIONS

There is a high antimicrobial resistance prevalence and increasing antimicrobial resistance trends among K. pneumoniae isolates from female outpatients in the United States with presumed uncomplicated urinary tract infection. Awareness of K. pneumoniae antimicrobial resistance helps to optimize empiric uncomplicated urinary tract infection treatment.

High-level nitrofurantoin resistance in a clinical isolate of Klebsiella pneumoniae: a comparative genomics and metabolomics analysis

Nitrofurantoin is a commonly used chemotherapeutic agent in the treatment of uncomplicated urinary tract infections caused by the problematic multidrug resistant Gram-negative pathogen Klebsiella pneumoniae. The present study aims to elucidate the mechanism of nitrofurantoin action and high-level resistance in K. pneumoniae using whole-genome sequencing (WGS), qPCR analysis, mutation structural modeling and untargeted metabolomic analysis. WGS profiling of evolved highly resistant mutants (nitrofurantoin minimum inhibitory concentrations > 256 mg/L) revealed modified expression of several genes related to membrane transport (porin ompK36 and efflux pump regulator oqxR) and nitroreductase activity (ribC and nfsB, involved in nitrofurantoin reduction). Untargeted metabolomics analysis of total metabolites extracted at 1 and 4 h post-nitrofurantoin treatment revealed that exposure to the drug caused a delayed effect on the metabolome which was most pronounced after 4 h. Pathway enrichment analysis illustrated that several complex interrelated metabolic pathways related to nitrofurantoin bacterial killing (aminoacyl-tRNA biosynthesis, purine metabolism, central carbohydrate metabolism, and pantothenate and CoA biosynthesis) and the development of nitrofurantoin resistance (riboflavin metabolism) were significantly perturbed. This study highlights for the first time the key role of efflux pump regulator oqxR in nitrofurantoin resistance and reveals global metabolome perturbations in response to nitrofurantoin, in K. pneumoniae.IMPORTANCEA quest for novel antibiotics and revitalizing older ones (such as nitrofurantoin) for treatment of difficult-to-treat Gram-negative bacterial infections has become increasingly popular. The precise antibacterial activity of nitrofurantoin is still not fully understood. Furthermore, although the prevalence of nitrofurantoin resistance remains low currently, the drug's fast-growing consumption worldwide highlights the need to comprehend the emerging resistance mechanisms. Here, we used multidisciplinary techniques to discern the exact mechanism of nitrofurantoin action and high-level resistance in Klebsiella pneumoniae, a common cause of urinary tract infections for which nitrofurantoin is the recommended treatment. We found that the expression of multiple genes related to membrane transport (including active efflux and passive diffusion of drug molecules) and nitroreductase activity was modified in nitrofurantoin-resistant strains, including oqxR, the transcriptional regulator of the oqxAB efflux pump. Furthermore, complex interconnected metabolic pathways that potentially govern the nitrofurantoin-killing mechanisms (e.g., aminoacyl-tRNA biosynthesis) and nitrofurantoin resistance (riboflavin metabolism) were significantly inhibited following nitrofurantoin treatment. Our study could help inform the improvement of nitrofuran derivatives, the development of new pharmacophores, or drug combinations to support the resurgence of nitrofurantoin in the management of multidrug resistant K. pneumouniae infection.

Susceptibility to Fosfomycin and Nitrofurantoin of ESBL-Positive Escherichia coli and Klebsiella pneumoniae Isolated From Urine of Pediatric Patients

BACKGROUND

Pediatric urinary tract infection (UTI) caused by extended-spectrum β-lactamase (ESBL)-positive gram-negative bacilli (GNB) has limited options for oral antibiotic treatment. The purpose of this study was to investigate the susceptibility of ESBL-positive Escherichia coli and Klebsiella pneumoniae isolates from pediatric urine samples to two oral antibiotics (fosfomycin and nitrofurantoin).

METHODS

From November 2020 to April 2022, ESBL-positive E. coli and K. pneumoniae isolates from urine samples were collected at Samsung Medical Center, Seoul, Korea. Patients over 18 years of age or with malignancy were excluded. For repeated isolates from the same patient, only the first isolate was tested. Minimum inhibitory concentrations (MICs) were measured using agar (fosfomycin) or broth (nitrofurantoin) dilution methods. MIC50 and MIC90 were measured for fosfomycin and nitrofurantoin in both E. coli and K. pneumoniae.

RESULTS

There were 117 isolates from 117 patients, with a median age of 7 months (range, 0.0-18.5 years). Among 117 isolates, 92.3% (108/117) were E. coli and 7.7% (9/117) were K. pneumoniae. Isolates from the pediatric intensive care unit (PICU) and general ward (GW) was 11.1% (13/117) and 88.9% (104/117), respectively. Among 108 E. coli isolates, MIC50 and MIC90 for fosfomycin were 0.5 μg/mL and 2 μg/mL, respectively. Fosfomycin susceptibility rate was 97.2% (105/108) with a breakpoint of 128 μg/mL. Fosfomycin susceptibility rate was significantly lower in PICU isolates than in GW isolates (81.8% vs. 99.0%, P = 0.027). For nitrofurantoin, both the MIC50 and MIC90 were 16 μg/mL. Nitrofurantoin susceptibility rate was 96.3% (104/108) with a breakpoint of 64 μg/mL based on Clinical and Laboratory Standards Institute guidelines. Among the nine K. pneumoniae isolates, the MIC50 and MIC90 for fosfomycin was 2 μg/mL and 32 μg/mL, respectively. MIC50 and MIC90 for nitrofurantoin were 64 μg/mL and 128 μg/mL, respectively.

CONCLUSION

For uncomplicated UTI caused by ESBL-positive GNB in Korean children, treatment with fosfomycin and nitrofurantoin for E. coli infections can be considered as an effective oral therapy option.

Evaluation of mono and combined nitrofurantoin therapy for toxoplasmosis in vivo using murine model

Toxoplasmosis is a frequent disease with an estimated prevalence of more than one billion human cases worldwide and over one million new infections each year. It is classified as a neglected tropical disease by the CDC since 2019. The disease may pass unnoticed in healthy individuals but could be fatal in the immunocompromised. Moreover, no effective treatment is available against the chronic form of the disease. Available anti-Toxoplasma drugs are associated with many side effects. Therefore, search for new more reliable, more efficient, and less toxic therapeutic agents is a continuous endeavor. This study assesses the potential use of nitrofurantoin, a compound with well-established antimicrobial properties, as a potential anti-Toxoplasma drug in vivo. It compares its efficacy to the commonly used anti-Toxoplasma agent spiramycin by molecular and histopathological methods in acute and chronic infection. The results demonstrate a significant ability to eliminate the parasite (P < 0.001) whether used as mono- or combined therapy with spiramycin in the acute and chronic stages. When compared to the anti-Toxoplasma drug spiramycin, nitrofurantoin achieved similar efficacy in the acute and chronic infection (P = 0.65 and P = 0.096, respectively). However, better results were obtained when using a combination of both drugs (P < 0.001). Additionally, nitrofurantoin showed good inhibitory effects on the inflammatory process in the liver, kidney, and uterus of the experimentally infected animals. In conclusion, nitrofurantoin can be considered as a potential anti-Toxoplasma agent. Nevertheless, further studies are recommended before consideration for clinical trials.

Intrinsic insights to antimicrobial effects of Nitrofurantoin to multi drug resistant Salmonella enterica serovar Typhimurium ms202

Emerging multidrug resistant (MDR) serovar of Salmonella has raised the concern of their impactful effect on pathogenic infection and mortality in human lead by the enteric diseases. In order to combat the battle against these MDR Salmonella pathogen, new drug molecules need to be evaluated for their potent antibacterial application. This study evaluates the mechanistic antimicrobial effect of nitrofurantoin against a MDR strain of Salmonella named S. enterica Typhimurium ms202. The antimicrobial effect of nitrofurantoin was studied through experimental and computational approach using standard microbiological and molecular techniques like growth curve analysis, live-dead analysis, oxidative stress evaluation using high throughput techniques like flow cytometry and fluorescent microscopy. The result showed a potent dose dependent antibacterial effect of nitrofurantoin against S. enterica Typhimurium ms202 with a MIC value of 64 µg/ml. Moreover, the mechanistic excavation of the phenomenon described the mechanism as an effect of molecular interaction of nitrofurantoin molecule with membrane receptor proteins OmpC of S. enterica Typhimurium ms202 leading to internalization of the nitrofurantoin heading towards the occurrence of cellular physiological disturbances through oxidative stress impeded by nitrofurantoin-Sod1 C protein interaction. The results indicated towards a synergistic effect of membrane damage, oxidative stress and genotoxicity for the antibacterial effect of nitrofurantoin against S. enterica Typhimurium ms202. The study described the potent dose-dependent application of nitrofurantoin molecule against MDR strains of Salmonella and guided towards their use in further discovered MDR strains.

Tackling the emerging Artemisinin-resistant malaria parasite by modulation of defensive oxido-reductive mechanism via nitrofurantoin repurposing

Oxidative stress-mediated cell death has remained the prime parasiticidal mechanism of front line antimalarial, artemisinin (ART). The emergence of resistant Plasmodium parasites characterized by oxidative stress management due to impaired activation of ART and enhanced reactive oxygen species (ROS) detoxification has decreased its clinical efficacy. This gap can be filled by development of alternative chemotherapeutic agents to combat resistance defense mechanism. Interestingly, repositioning of clinically approved drugs presents an emerging approach for expediting antimalarial drug development and circumventing resistance. Herein, we evaluated the antimalarial potential of nitrofurantoin (NTF), a clinically used antibacterial drug, against intra-erythrocytic stages of ART-sensitive (Pf3D7) and resistant (PfKelch13R539T) strains of P. falciparum, alone and in combination with ART. NTF exhibited growth inhibitory effect at submicro-molar concentration by arresting parasite growth at trophozoite stage. It also inhibited the survival of resistant parasites as revealed by ring survival assay. Concomitantly, in vitro combination assay revealed synergistic association of NTF with ART. NTF was found to enhance the reactive oxygen and nitrogen species, and induced mitochondrial membrane depolarization in parasite. Furthermore, we found that exposure of parasites to NTF disrupted redox balance by impeding Glutathione Reductase activity, which manifests in enhanced oxidative stress, inducing parasite death. In vivo administration of NTF, alone and in combination with ART, in P. berghei ANKA-infected mice blocked parasite multiplication and enhanced mean survival time. Overall, our results indicate NTF as a promising repurposable drug with therapeutic potential against ART-sensitive as well as resistant parasites.

CpxA/R-Controlled Nitroreductase Expression as Target for Combinatorial Therapy against Uropathogens by Promoting Reactive Oxygen Species Generation

The antibiotic resistances emerged in uropathogens lead to accumulative treatment failure and recurrent episodes of urinary tract infection (UTI), necessitating more innovative therapeutics to curb UTI before systematic infection. In the current study, the combination of amikacin and nitrofurantoin is found to synergistically eradicate Gram-negative uropathogens in vitro and in vivo. The mechanistic analysis demonstrates that the amikacin, as an aminoglycoside, induced bacterial envelope stress by introducing mistranslated proteins, thereby constitutively activating the cpxA/R two-component system (Cpx signaling). The activation of Cpx signaling stimulates the expression of bacterial major nitroreductases (nfsA/nfsB) through soxS/marA regulons. As a result, the CpxA/R-dependent nitroreductases overexpression generates considerable quantity of lethal reactive intermediates via nitroreduction and promotes the prodrug activation of nitrofurantoin. As such, these actions together disrupt the bacterial cellular redox balance with excessively-produced reactive oxygen species (ROS) as "Domino effect", accelerating the clearance of uropathogens. Although aminoglycosides are used as proof-of-principle to elucidate the mechanism, the synergy between nitrofurantoin is generally applicable to other Cpx stimuli. To summarize, this study highlights the potential of aminoglycoside-nitrofurantoin combination to replenish the arsenal against recurrent Gram-negative uropathogens and shed light on the Cpx signaling-controlled nitroreductase as a potential target to manipulate the antibiotic susceptibility.

Oral administration of an extended-release formulation of nitrofurantoin results in high concentrations in the urine of dogs

OBJECTIVE

Sporadic bacterial cystitis in both dogs and humans is often caused by Escherichia coli. In humans, nitrofurantoin is a first-line antimicrobial for the treatment of bacterial cystitis but in dogs a lack of available data may be part of the reason it is only recommended as a second-line treatment. The objective of this preliminary study was to determine the plasma pharmacokinetics and urine concentrations of nitrofurantoin monohydrate-macrocrystalline in dogs.

ANIMALS

8 healthy female hound dogs.

PROCEDURES

From July 26 to July 28, 2021, dogs received a single oral dose of nitrofurantoin monohydrate-macrocrystalline 100 mg with food. Blood and urine were collected at predetermined times. Nitrofurantoin concentrations were assayed by UPLC-MS/MS and plasma data were analyzed using noncompartmental methods.

RESULTS

Plasma concentrations were low for all dogs with a mean ± SD maximum concentration (Cmax) of 0.242 ± 0.098 μg/mL (range, 0.14 to 0.42 µg/mL) occurring between 2 and 24 hours. Urine concentrations were manyfold higher than for plasma. Cmax in urine was 134 ± 54 µg/mL (range, 49.1 to 218 µg/mL) occurring between 6 and 36 hours. As seen in other species, nitrofurantoin concentrated in urine with concentrations being 500 times higher than the concentration in plasma.

CLINICAL RELEVANCE

Results suggested that nitrofurantoin monohydrate-macrocrystalline formulation of nitrofurantoin should be effective in treating bacterial cystitis caused by susceptible uropathogens.

Dynamics of microbial communities during biotransformation of nitrofurantoin

The purpose of this research was to investigate the biodegradation of nitrofurantoin (NFT), a typical nitrofuran antibiotic of potential carcinogenic properties, by two microbial communities derived from distinct environmental niches - mountain stream (NW) and seaport water (SS). The collected environmental samples represent the reserve of the protected area with no human intervention and the contaminated area that concentrates intense human activities. The structure, composition, and diversity of the communities were analyzed at three timepoints during NFT biodegradation. Comamonadaceae (43.2%) and Pseudomonadaceae (19.6%) were the most abundant families in the initial NW sample. The top families in the initial SS sample included Aeromonadaceae (31.4%) and Vibrionaceae (25.3%). The proportion of the most abundant families in both consortia was remarkably reduced in all samples treated with NFT. The biodiversity significantly increased in both consortia treated with NFT suggesting that NFT significantly alters community structure in the aquatic systems. In this study, NFT removal efficiency and transformation products were also studied. The biodegradation rate decreased with the increasing initial NFT concentration. Biodegradation followed similar pathways for both consortia and led to the formation of transformation products: 1-aminohydantoin, semicarbazide (SEM), and hydrazine (HYD). SEM and HYD were detected for the first time as NFT biotransformation products. This study demonstrates that the structure of the microbial community may be directly correlated with the presence of NFT. Enchanced biodiversity of the microbial community does not have to be correlated with increase in functional capacity, such as the ability to biodegradation because higher biodiversity corresponded to lower biodegradation. Our findings provide new insights into the effect of NFT contamination on aquatic microbiomes. The study also increases our understanding of the environmental impact of nitrofuran residues and their biodegradation.

Exploring the in situ evolution of nitrofurantoin resistance in clinically derived uropathogenic Escherichia coli isolates

BACKGROUND

Nitrofurantoin has been re-introduced as a first-choice antibiotic to treat uncomplicated acute urinary tract infections in England and Wales. Highly effective against common uropathogens such as Escherichia coli, its use is accompanied by a low incidence (<10%) of antimicrobial resistance. Resistance to nitrofurantoin is predominantly via the acquisition of loss-of-function, step-wise mutations in the nitroreductase genes nfsA and nfsB.

OBJECTIVE

To explore the in situ evolution of NitR in E. coli isolates from 17 patients participating in AnTIC, a 12-month open label randomized controlled trial assessing the efficacy of antibiotic prophylaxis in reducing urinary tract infections (UTIs) incidence in clean intermittent self-catheterizing patients.

METHODS

The investigation of NitR evolution in E. coli used general microbiology techniques and genetics to model known NitR mutations in NitSE. coli strains.

RESULTS

Growth rate analysis identified a 2%-10% slower doubling time for nitrofurantoin resistant strains: NitS: 20.8 ± 0.7 min compared to NitR: 23 ± 0.8 min. Statistically, these data indicated no fitness advantage of evolved strains compared to the sensitive predecessor (P-value = 0.13). Genetic manipulation of E. coli to mimic NitR evolution, supported no fitness advantage (P-value = 0.22). In contrast, data argued that a first-step mutant gained a selective advantage, at sub-MIC (4-8 mg/L) nitrofurantoin concentrations.

CONCLUSION

Correlation of these findings to nitrofurantoin pharmacokinetic data suggests that the low incidence of E. coli NitR, within the community, is driven by urine-based nitrofurantoin concentrations that selectively inhibit the growth of E. coli strains carrying the key first-step loss-of-function mutation.

Alkaline Urine in the Emergency Department Predicts Nitrofurantoin Resistance

BACKGROUND

The Proteeae group (i.e., Proteus species, Morganella morganii, and Providencia species) frequently causes urinary tract infections (UTIs) and is generally resistant to nitrofurantoin. Proteeae species can produce urease, which can increase urine pH.

OBJECTIVE

Our aim was to determine whether higher urine pH in the emergency department is associated with nitrofurantoin resistance.

METHODS

A single health system database of emergency department patients aged 18 years and older who received urinalysis between April 18, 2014, and March 7, 2017, was examined using χ² test and multivariable regression analysis.

RESULTS

Of 67,271 urine samples analyzed, 13,456 samples grew a single bacterial species. Urine cultures growing the Proteeae group were associated with significantly more alkaline urine than other bacteriuria cultures (odds ratio [OR] 2.20, 95% confidence interval [CI] 2.06-2.36; p < 0.001). The Proteeae species represented 4.4% of urine samples at pH 5-7, 24.4% at pH 8-9, and 40.0% at pH 9. At urine pH 5-7, 80.4% of urine samples were sensitive to nitrofurantoin; however, this percentage decreased to 66.1% for urine pH 8-9 and 54.6% for urine pH 9. Nitrofurantoin had the highest OR (2.10, 95% CI 1.85-2.39) among cefazolin, ciprofloxacin, and trimethoprim/sulfamethoxazole for bacteriuria sensitive to those antibiotics at urine pH 5-7. At urine pH 8-9 and 9, nitrofurantoin had the lowest OR among the antibiotics: 0.48 (95% CI 0.42-0.54) and 0.31 (95% CI 0.24-0.40), respectively (p < 0.001 for both).

CONCLUSIONS

Urine pH of 8 or higher is associated with high rates of nitrofurantoin resistance.

Alterations in chromosomal genes nfsA, nfsB, and ribE are associated with nitrofurantoin resistance in Escherichia coli from the United Kingdom

Antimicrobial resistance in enteric or urinary Escherichia coli is a risk factor for invasive E. coli infections. Due to widespread trimethoprim resistance amongst urinary E. coli and increased bacteraemia incidence, a national recommendation to prescribe nitrofurantoin for uncomplicated urinary tract infection was made in 2014. Nitrofurantoin resistance is reported in <6% urinary E. coli isolates in the UK, however, mechanisms underpinning nitrofurantoin resistance in these isolates remain unknown. This study aimed to identify the genetic basis of nitrofurantoin resistance in urinary E. coli isolates collected from north west London and then elucidate resistance-associated genetic alterations in available UK E. coli genomes. As a result, an algorithm was developed to predict nitrofurantoin susceptibility. Deleterious mutations and gene-inactivating insertion sequences in chromosomal nitroreductase genes nfsA and/or nfsB were identified in genomes of nine confirmed nitrofurantoin-resistant urinary E. coli isolates and additional 11 E. coli isolates that were highlighted by the prediction algorithm and subsequently validated to be nitrofurantoin-resistant. Eight categories of allelic changes in nfsA, nfsB, and the associated gene ribE were detected in 12412 E. coli genomes from the UK. Evolutionary analysis of these three genes revealed homoplasic mutations and explained the previously reported order of stepwise mutations. The mobile gene complex oqxAB, which is associated with reduced nitrofurantoin susceptibility, was identified in only one of the 12412 genomes. In conclusion, mutations and insertion sequences in nfsA and nfsB were leading causes of nitrofurantoin resistance in UK E. coli. As nitrofurantoin exposure increases in human populations, the prevalence of nitrofurantoin resistance in carriage E. coli isolates and those from urinary and bloodstream infections should be monitored.

Prediction of nitrofurantoin resistance among Enterobacteriaceae and mutational landscape of in vitro selected resistant E. coli

Nitrofurantoin (NIT) has long been a drug of choice in the treatment of lower urinary tract infections. Recent emergence of NIT resistant Enterobacteriaceae is a global concern. An ordinal logistic regression model based on PCR amplification patterns of five genes associated with NIT resistance (nfsA, nfsB, ribE, oqxA, and oqxB) among 100 clinical Enterobacteriaceae suggested that a combination of oqxB, nfsB, ribE, and oqxA is ideal for NIT resistance prediction. In addition, four Escherichia coli NIT-resistant mutants were in vitro generated by exposing an NIT-susceptible E. coli to varying concentrations of NIT. The in vitro selected NIT resistant mutants (NI2, NI3, NI4 and NI5) were found to have mutations resulting in frameshifts, premature/lost stop codons or failed amplification of nfsA and/or nfsB genes. The in vitro selected NI5 and the transductant colonies with reconstructed NI5 genotype exhibited reduced fitness compared to their parent strain NS30, while growth of a resistant clinical isolate (NR42) was found to be unaffected in the absence of NIT. These results emphasize the importance of strict adherence to prescribed antibiotic treatment regimens and dosage duration. If left unchecked, these resistant bacteria may thrive at sub-therapeutic concentrations of NIT and spread in the community.

Resistance to nitrofurantoin is an indicator of extensive drug-resistant (XDR) Enterobacteriaceae

Introduction. Nitrofurantoin is one of the preferred antibiotics in the treatment of uropathogenic multidrug-resistant (MDR) infections. However, resistance to nitrofurantoin in extensively drug-resistant (XDR) bacteria has severely limited the treatment options.Gap statement. Information related to co-resistance or collateral sensitivity (CS) with reference to nitrofurantoin resistant bacteria is limited.Aim. To study the potential of nitrofurantoin resistance as an indicator of the XDR phenotype in Enterobacteriaceae.Methods. One hundred (45 nitrofurantoin-resistant, 21 intermediately resistant and 34 nitrofurantoin-susceptible) Enterobacteriaceae were analysed in this study. Antibiotic susceptibility testing (AST) against nitrofurantoin and 17 other antimicrobial agents across eight different classes was performed by using the Vitek 2.0 system. The isolates were screened for the prevalence of acquired antimicrobial resistance (AMR) and efflux pump genes by PCR.Results. In total, 51 % of nitrofurantoin-resistant and 28 % of intermediately nitrofurantoin resistant isolates exhibited XDR characteristics, while only 3 % of nitrofurantoin-sensitive isolates were XDR (P=0.0001). Significant co-resistance was observed between nitrofurantoin and other tested antibiotics (β-lactam, cephalosporin, carbapenem, aminoglycoside and tetracycline). Further, the prevalence of AMR and efflux pump genes was higher in the nitrofurantoin-resistant strains compared to the susceptible isolates. A strong association was observed between nitrofurantoin resistance and the presence of bla _PER-1, bla _NDM-1, bla _OXA-48, ant(2) and oqxA-oqxB genes. Tigecycline (84 %) and colistin (95 %) were the only antibiotics to which the majority of the isolates were susceptible.Conclusion. Nitrofurantoin resistance could be an indicator of the XDR phenotype among Enterobacteriaceae, harbouring multiple AMR and efflux pump genes. Tigecycline and colistin are the only antibiotics that could be used in the treatment of such XDR infections. A deeper understanding of the co-resistance mechanisms in XDR pathogens and prescription of AST-based appropriate combination therapy may help mitigate this problem.

CombiANT: Antibiotic interaction testing made easy

Antibiotic combination therapies are important for the efficient treatment of many types of infections, including those caused by antibiotic-resistant pathogens. Combination treatment strategies are typically used under the assumption that synergies are conserved across species and strains, even though recent results show that the combined treatment effect is determined by specific drug–strain interactions that can vary extensively and unpredictably, both between and within bacterial species. To address this problem, we present a new method in which antibiotic synergy is rapidly quantified on a case-by-case basis, allowing for improved combination therapy. The novel CombiANT methodology consists of a 3D-printed agar plate insert that produces defined diffusion landscapes of 3 antibiotics, permitting synergy quantification between all 3 antibiotic pairs with a single test. Automated image analysis yields fractional inhibitory concentration indices (FICis) with high accuracy and precision. A technical validation with 3 major pathogens, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, showed equivalent performance to checkerboard methodology, with the advantage of strongly reduced assay complexity and costs for CombiANT. A synergy screening of 10 antibiotic combinations for 12 E. coli urinary tract infection (UTI) clinical isolates illustrates the need for refined combination treatment strategies. For example, combinations of trimethoprim (TMP) + nitrofurantoin (NIT) and TMP + mecillinam (MEC) showed synergy, but only for certain individual isolates, whereas MEC + NIT combinations showed antagonistic interactions across all tested strains. These data suggest that the CombiANT methodology could allow personalized clinical synergy testing and large-scale screening. We anticipate that CombiANT will greatly facilitate clinical and basic research of antibiotic synergy.

Existing methods for identifying efficient combinations of antibiotics are time-consuming and costly, restricting their use in clinics and research. This study describes the novel CombiANT methodology, which uses defined diffusion landscapes of three antibiotics to permit rapid and low-cost synergy quantification between all antibiotic pairs.

Combined Effect of Nitrofurantoin and Plant Surfactant on Bacteria Phospholipid Membrane

Due to the increasing use of antibiotics, measures are being taken to improve their removal from the natural environment. The support of biodegradation with natural surfactants that increase the bioavailability of impurities for microorganisms that degrade them, raises questions about their effect on bacterial cells. In this paper we present analysis of the interaction of nitrofurantoin (NFT) and saponins from the Saponaria officinalis on the environmental bacteria membrane and the model phospholipid membrane mimicking it. A wide perspective of the process is provided with the Langmuir monolayer technique and membrane permeability test with bacteria. The obtained results showed that above critical micelle concentration (CMC), saponin molecules are incorporated into the POPE monolayer, but the NFT impact was ambiguous. What is more, differences in membrane permeability between the cells exposed to NFT in comparison to that of the non-exposed cells were observed above 1.0 CMC for Achromobacter sp. KW1 or above 0.5 CMC for Pseudomonas sp. MChB. In both cases, NFT presence lowered the membrane permeability. Moreover, the Congo red adhesion to the cell membrane also decreased in the presence of a high concentration of surfactants and NFT. The results suggest that saponins are incorporated into the bacteria membrane, but their sugar hydrophilic part remains outside, which modifies the adsorption properties of the cell surface as well as the membrane permeability.

Effect of different drugs and drug combinations on killing stationary phase and biofilms recovered cells of Bartonella henselae in vitro

BACKGROUND

Bartonella henselae is a Gram-negative bacterium transmitted to humans by a scratch from cat in the presence of ectoparasites. Humans infected with B. henselae can result in various clinical diseases including local lymphadenopathy and more serious systemic disease such as persistent bacteremia and endocarditis. The current treatment of persistent B. henselae infections is not very effective and remains a challenge. To find more effective treatments for persistent and biofilm Bartonella infections, in this study, we evaluated a panel of drugs and drug combinations based on the current treatment and also promising hits identified from a recent drug screen against stationary phase and biofilm recovered cells of B. henselae.

RESULTS

We evaluated 14 antibiotics and 25 antibiotic combinations for activity against stationary phase B. henselae (all antibiotics were at 5 μg/ml) and found that ciprofloxacin, gentamicin, and nitrofurantoin were the most active agents, while clofazimine and miconazole had poor activity. Drug combinations azithromycin/ciprofloxacin, azithromycin/methylene blue, rifampin/ciprofloxacin, and rifampin/methylene blue could rapidly kill stationary phase B. henselae with no detectable CFU after 1-day exposure. Methylene blue and rifampin were the most active agents against the biofilm B. henselae after 6 days of drug exposure. Antibiotic combinations (azithromycin/ciprofloxacin, azithromycin/methylene blue, rifampin/ciprofloxacin, rifampin/methylene blue) completely eradicated the biofilm B. henselae after treatment for 6 days.

CONCLUSIONS

These findings may facilitate development of more effective treatment of persistent Bartonella infections in the future.

Single-step synthesis and in vitro anti-mycobacterial activity of novel nitrofurantoin analogues

The emergence of drug-resistant tuberculosis (DR-TB) as well as the requirement for long, expensive and toxic drug regimens impede efforts to control and eliminate TB. Therefore, there's a need for effective and affordable anti-mycobacterial agents which can shorten the duration of therapy and are active against Mycobacterium tuberculosis (Mtb) in both active and latent phases. Nitrofurantoin (NFT) is a hypoxic agent with activity against a myriad of anaerobic pathogens and, like the first-line TB drug, rifampicin (RIF), kills non-replicating bacilli. However, the poor ability of NFT to cross host cell membranes and penetrate tissue means that it does not reach therapeutic concentrations. To improve TB efficacy of NFT, a series of NFT analogues was synthesized and evaluated in vitro for anti-mycobacterial activity against the laboratory strain, Mtb H37Rv, and for potential cytotoxicity using human embryonic kidney (HEK-293) and Chinese hamster ovarian (CHO) cells. The NFT analogues showed good safety profiles, enhanced anti-mycobacterial potency, improved lipophilicity, as well as reduced protein binding affinity. Analogue 9 which contains an eight carbon aliphatic chain was the most active, equipotent to isoniazid (INH), a major front-line agent, with MIC₉₀ = 0.5 μM, 30-fold more potency than the parent drug, nitrofurantoin (MIC₉₀ = 15 μM), and 100-fold more selective towards mycobacteria. Therefore, 9 was identified as a validated hit for further investigation in the urgent search for new, safe and affordable TB drugs.

Conserved collateral antibiotic susceptibility networks in diverse clinical strains of Escherichia coli

There is urgent need to develop novel treatment strategies to reduce antimicrobial resistance. Collateral sensitivity (CS), where resistance to one antimicrobial increases susceptibility to other drugs, might enable selection against resistance during treatment. However, the success of this approach would depend on the conservation of CS networks across genetically diverse bacterial strains. Here, we examine CS conservation across diverse Escherichia coli strains isolated from urinary tract infections. We determine collateral susceptibilities of mutants resistant to relevant antimicrobials against 16 antibiotics. Multivariate statistical analyses show that resistance mechanisms, in particular efflux-related mutations, as well as the relative fitness of resistant strains, are principal contributors to collateral responses. Moreover, collateral responses shift the mutant selection window, suggesting that CS-informed therapies may affect evolutionary trajectories of antimicrobial resistance. Our data allow optimism for CS-informed therapy and further suggest that rapid detection of resistance mechanisms is important to accurately predict collateral responses.

Diversity of Carbapenemase-Producing Escherichia coli Isolates in France in 2012-2013

With the dissemination of carbapenemase-producing Enterobacteriaceae (CPE) strains worldwide, carbapenem-hydrolyzing enzymes are increasingly reported among isolates of Escherichia coli, the first hospital and community-acquired opportunistic pathogen. Here, we have performed an epidemiological survey of carbapenemase-producing E. coli (CP-Ec) isolates received at the French National Reference Centre (F-NRC) in 2012 and 2013. Antimicrobial susceptibilities for last-resort antibiotics and antimicrobial compounds commonly used to treat urinary tract infections were determined by broth microdilution. Clonal relationship was assessed using repetitive sequence-based PCR (rep-PCR) and multilocus sequence typing (MLST). From this collection of 140 carbapenemase-producing E. coli isolates, 74% produced an OXA-48-like carbapenemase and 21% produced an NDM carbapenemase. A link with a foreign country was suspected for 37% of infected/colonized patients. Most of the isolates were from screening (56%) and from urine samples (26%). Colistin, fosfomycin, and nitrofurantoin possessed the most consistent activity, with 100%, 95%, and 96% isolates susceptible, respectively. A wide diversity of carbapenemase-producing E. coli isolates has been found (50 different sequence types [STs]). The most prevalent clones were (i) E. coli sequence type 38 (ST38) producing OXA-48 (n = 21), a clone linked to Turkey and North African countries, (ii) E. coli ST-90 producing OXA-204 (n = 9), which was responsible for an outbreak related to a contaminated duodenoscope, and (iii) E. coli ST-410 producing OXA-181 (n = 5), which was recovered from patients of different geographical origins. These specific clones might be considered high-risk clones for the dissemination of carbapenemases in E. coli The wide diversity of STs, combined with the increasing number of CP-Ec isolates received by the F-NRC, suggests a likely dissemination of CP-Ec isolates in the community.

Urinary pathogenic bacterial profile, antibiogram of isolates and associated risk factors among pregnant women in Ambo town, Central Ethiopia: a cross-sectional study

Background

Urinary tract infection (UTI) is a well-known bacterial infection posing serious health problem in pregnant women. A study was conducted in pregnant women with the objectives of estimating prevalence of UTI, determining antibiogram of the bacterial isolates and assessment of the potential risk factors associated with UTI.

Methods

A cross-sectional study design was used to collect 300 mid-stream urine samples from pregnant women from March 2016 to December, 2016. Samples were inoculated into Cysteine Lactose Electrolyte Deficient medium (CLED). Colonies from CLED were subcultured onto MacConkey and Blood agar plates. A standard agar disc diffusion method was used to determine antimicrobial susceptibility. Chi-square (X2) test & logistic regression were used to show associations between UTI and explanatory variables & identify the predictors of UTI, respectively.

Results

The age of pregnant women enrolled in this study ranges from 16 to 46 years (mean ± standard deviation = 25 ± 4.7 years).The overall prevalence of UTI in pregnant women was 18.7% (95% confidence interval [CI]: 14.4-23.54%).The prevalence of symptomatic and asymptomatic UTI was 20.4% (95% CI: 13.09-29.46%) and 17.8% (95% CI: 12.70-23.83%) respectively. The predominant bacteria identified were E. coli (46.4%), S. aureus (14.3%), coagulase negative Staphylococci [CoNS] (14.3%) and Proteus species (10.6%). Majority of Gram-negative bacteria isolates were resistant to ampicillin (70%), ceftriaxon (66%), gentamicin (68%) and nitrofurantoin (64%) while 75-100% of the Gram positive isolates were resistance to ampicillin. Multiple drug resistance was observed in all of the isolates. Multivariable logistic regression revealed that the odds of acquiring UTI was 4.78 times higher in pregnant women earning monthly income of ≤500 Ethiopian Birr (21.18 USD) as compared to those earning monthly income >2001 Ethiopian Birr [84.79 USD] (P = 0.046). Similarly, the risk of UTI was higher in those who eat raw meat (OR = 2.04, 95% CI: 1.09, 3.83, P = 0.026) and had previous UTI history (OR = 2.29, 95% CI = 1.15-4.56, P = 0.019) as compared to those who eat cooked meat and had no previous history of UTI.

Conclusions

The prevalence & antimicrobial resistance of uropathogens was high. Health education, continuous surveillance of UTI and their antimicrobial resistance pattern are essential to reduce the consequence of symptomatic and asymptomatic bacteriuria and multi-drug resistant bacteria in pregnant women.

Antibiotic Resistance of Bacteria Involved in Urinary Infections in Brazil: A Cross-Sectional and Retrospective Study

Empirical and prolonged antimicrobial treatment of urinary tract infections caused by Escherichia coli is associated with the emergence of bacterial resistance, and not all countries have strict policies against the indiscriminate use of drugs in order to prevent resistance. This cross-sectional and retrospective study (2010–2015) aimed to evaluate the sensitivity and resistance of patient-derived E. coli to different drugs broadly used to treat urinary infections in Brazil: ampicillin + sulbactam, cephalothin, ciprofloxacin, norfloxacin, and nitrofurantoin. We obtained 1654 E. coli samples from ambulatory patients with disease symptoms of the urinary tract from a Brazilian public hospital. While all antibiotics were effective in killing E. coli to a large degree, nitrofurantoin was the most effective, with fewer samples exhibiting antibiotic resistance. We assessed the costs of generic and brand name versions of each antibiotic. Nitrofurantoin, the most effective antibiotic, was the cheapest, followed by the fluoroquinolones (ciprofloxacin and norfloxacin), ampicillin + sulbactam and, lastly, cephalothin. Finally, assessment of antibiotic resistance to fluoroquinolones over the study period and extrapolation of the data led to the conclusion that these antibiotics could no longer be effective against E. coli-based urinary infections in approximately 20 years if their indiscriminate use in empirical treatment continues.

Predictors of Antimicrobial Resistance among Pathogens Causing Urinary Tract Infection in Children

OBJECTIVE

To determine which children with urinary tract infection are likely to have pathogens resistant to narrow-spectrum antimicrobials.

STUDY DESIGN

Children, 2-71 months of age (n = 769) enrolled in the Randomized Intervention for Children with Vesicoureteral Reflux or Careful Urinary Tract Infection Evaluation studies were included. We used logistic regression models to test the associations between demographic and clinical characteristics and resistance to narrow-spectrum antimicrobials.

RESULTS

Of the included patients, 91% were female and 76% had vesicoureteral reflux. The risk of resistance to narrow-spectrum antibiotics in uncircumcised males was approximately 3 times that of females (OR 3.1; 95% CI 1.4-6.7); in children with bladder bowel dysfunction, the risk was 2 times that of children with normal function (OR 2.2; 95% CI 1.2-4.1). Children who had received 1 course of antibiotics during the past 6 months also had higher odds of harboring resistant organisms (OR 1.6; 95% CI 1.1-2.3). Hispanic children had higher odds of harboring pathogens resistant to some narrow-spectrum antimicrobials.

CONCLUSIONS

Uncircumcised males, Hispanic children, children with bladder bowel dysfunction, and children who received 1 course of antibiotics in the past 6 months were more likely to have a urinary tract infection caused by pathogens resistant to 1 or more narrow-spectrum antimicrobials.

Quantifying the Determinants of Evolutionary Dynamics Leading to Drug Resistance

The emergence of drug resistant pathogens is a serious public health problem. It is a long-standing goal to predict rates of resistance evolution and design optimal treatment strategies accordingly. To this end, it is crucial to reveal the underlying causes of drug-specific differences in the evolutionary dynamics leading to resistance. However, it remains largely unknown why the rates of resistance evolution via spontaneous mutations and the diversity of mutational paths vary substantially between drugs. Here we comprehensively quantify the distribution of fitness effects (DFE) of mutations, a key determinant of evolutionary dynamics, in the presence of eight antibiotics representing the main modes of action. Using precise high-throughput fitness measurements for genome-wide Escherichia coli gene deletion strains, we find that the width of the DFE varies dramatically between antibiotics and, contrary to conventional wisdom, for some drugs the DFE width is lower than in the absence of stress. We show that this previously underappreciated divergence in DFE width among antibiotics is largely caused by their distinct drug-specific dose-response characteristics. Unlike the DFE, the magnitude of the changes in tolerated drug concentration resulting from genome-wide mutations is similar for most drugs but exceptionally small for the antibiotic nitrofurantoin, i.e., mutations generally have considerably smaller resistance effects for nitrofurantoin than for other drugs. A population genetics model predicts that resistance evolution for drugs with this property is severely limited and confined to reproducible mutational paths. We tested this prediction in laboratory evolution experiments using the "morbidostat", a device for evolving bacteria in well-controlled drug environments. Nitrofurantoin resistance indeed evolved extremely slowly via reproducible mutations-an almost paradoxical behavior since this drug causes DNA damage and increases the mutation rate. Overall, we identified novel quantitative characteristics of the evolutionary landscape that provide the conceptual foundation for predicting the dynamics of drug resistance evolution.

Inhibition of Nitrofurantoin Reduction by Menthol Leads to Enhanced Antimicrobial Activity

Nitrofurantoin is a nitroaromatic compound used for the treatment of urinary tract infections. Nitrofurantoin activity is regulated by a nitroreduction process. It is first reduced by bacterial nitroreductases to active short-life intermediates, which are further converted to non-toxic molecules, which negatively affect its antibacterial activity. In this study we have shown that resistant strains of Klebsiella sp. inactivate the bactericidal activity of nitrofurantoin. Also we demonstrated a synergistic effect between menthol and nitrofurantoin bactericidal activities against nitrofurantoin susceptible Enterobacteriaceae.

Antibiotic susceptibility and resistance of Staphylococcus aureus isolated from fresh porcine skin xenografts: risk to recipients with thermal injury

The previous use of fresh porcine xenografts at the Prague Burn Centre had raised concerns over the transmission of zoonotic pathogens. This study examines the risk of zoonotic Staphylococcus aureus colonisation of burn patients from fresh porcine skin xenografts. Samples were collected from the nares, skin and perineum of commercial pigs (n=101) and were screened for methicillin sensitive S. aureus (MSSA) and resistant S. aureus (MRSA). The efficacy of the antibiotic wash used in decontamination of the pigskin was tested against planktonic- and biofilm-grown isolates. The spa type of each isolate was also confirmed. All pig swabs were negative for MRSA but 86% positive for MSSA. All planktonic-grown isolates of MSSA were sensitive to chloramphenicol and nitrofurantoin and 44% of isolates were resistant to streptomycin. Isolates grown as biofilm exhibited higher rates of antimicrobial resistance. Sequence analysis revealed three distinct spa types of the MRSA ST398 clonal type. This finding demonstrates the existence of a MSSA reservoir containing spa types resembling those of well-known MRSA strains. These MSSA exhibit resistance to antibiotics used for decontamination of the pigskin prior to xenograft. Amended use of procurement could allow the use of fresh pigskin xenografts to be reinstated.

Molecular subtyping and virulence gene analysis of Listeria monocytogenes isolates from food

A total of 67 Listeria monocytogenes isolates from 698 raw meat samples were characterized for molecular serogroup identification and antimicrobial susceptibility. Approximately one third (32.8%) of the isolates belonged to molecular serogroup 1/2a, 3a, followed by 1/2c, 3c (26.9%), 1/2b, 3b, 7 (22.4%), 4b, 4d, 4e (16.4%) and 4a, 4c (1.5%). Most of the L. monocytogenes isolates were susceptible to 14 antimicrobials tested but several were resistant to tetracycline, ciprofloxacin and nitrofurantoin. An additional 30 L. monocytogenes isolates from chicken and produce in our collection were also included to determine the presence of significant virulence markers. All 97 isolates carried inlC and inlJ except for a lineage III isolate 110-1. Most Listeriolysin S (LLS)-carrying isolates (11/12) belonged to lineage I, whereas the remaining one isolate belonged to lineage III. Five 4b, 4d, 4e isolates including two from turkey and three from produce belonged to Epidemic Clone I (ECI). Four molecular serogroup associated mutation types that lead to premature stop codons (PMSCs) in inlA were identified. PFGE and inlA sequence analysis results were concordant, and different virulence potential within 1/2a, 3a and 4b, 4d, 4e isolates were observed. The study revealed that a subset of isolates from meat and produce belonged to ECI, harbored inlC, inlJ and LLS, and produced full length InlA, suggesting that they be capable of causing human illness.

Microbiology of urinary tract infections in Gaborone, Botswana

OBJECTIVE

The microbiology and epidemiology of UTI pathogens are largely unknown in Botswana, a high prevalence HIV setting. Using laboratory data from the largest referral hospital and a private hospital, we describe the major pathogens causing UTI and their antimicrobial resistance patterns.

METHODS

This retrospective study examined antimicrobial susceptibility data for urine samples collected at Princess Marina Hospital (PMH), Bokamoso Private Hospital (BPH), or one of their affiliated outpatient clinics. A urine sample was included in our dataset if it demonstrated pure growth of a single organism and accompanying antimicrobial susceptibility and subject demographic data were available.

RESULTS

A total of 744 samples were included. Greater than 10% resistance was observed for amoxicillin, co-trimoxazole, amoxicillin-clavulanate, and ciprofloxacin. Resistance of E. coli isolates to ampicillin and co-trimoxazole was greater than 60% in all settings. HIV status did not significantly impact the microbiology of UTIs, but did impact antimicrobial resistance to co-trimoxazole.

CONCLUSIONS

Data suggests that antimicrobial resistance has already emerged to most oral antibiotics, making empiric management of outpatient UTIs challenging. Ampicillin, co-trimoxazole, and ciprofloxacin should not be used as empiric treatment for UTI in this context. Nitrofurantoin could be used for simple cystitis; aminoglycosides for uncomplicated UTI in inpatients.

Antibiotic susceptibility of vancomyin and nitrofurantoin in Staphylococcus aureus isolated from burnt patients in Sulaimaniyah, Iraqi Kurdistan

Burns remain a significant public health problem in terms of morbidity and mortality throughout the world, especially in low and middle-income countries. Burning raptures the skin barriers that normally prevent invasion by microorganisms and infection is a major complication in burn patients. Methicillin resistant Staphylococcus aureus (MRSA) is the most important nosocomial pathogen. This retrospective analysis was conducted in the burn unit of the Department of Microbiology in the Sulamaini Plastic Surgery and Burns Hospital. The analysis is based on data collected from the medical records of 2938 burn patients, hospitalized between May 2008 and December 2011. The clinical samples were taken from various body sources for microbiological tests. Patients with a high percentage of total body surface area burnt (P<0.001) and a longer hospital stay (P<0.001) were more likely to have infection compared to other patients. In addition, among all tested antibiotics, vancomycin and nitrofurantion seem to be the most effective antibiotics for MR- SA. Furthermore there was a significant association between age and antibiotic resistance for all antibiotics except for vancomycin and nitrofurantoin. Resistance to antibiotics increased with advancing age. The wide use of antibiotics in the treatment of bacterial infections has probably led to the emergence and spread of resistant strains. Routine microbiological surveillance and careful in vitro testing prior to antibiotic use and strict adherence to hospital antibiotic policy may help in the prevention and treatment of antibiotic resistant pathogens in burn infections.

Etiology and antimicrobial susceptibility pattern of bacterial pathogens from urinary tract infection

Urinary tract infection (UTI) is the most common infection in both community and hospital patients. In majority of the cases, empirical antimicrobial treatment is practiced before the laboratory results of urine culture. Thus, antibiotic resistance may increase in urinary bacterial pathogens due to improper use of drugs. This study was designed to find out the etiological agents of UTI and their prevalence, and to determine the antimicrobial susceptibility pattern of the bacterial pathogens isolated from urine culture. This study was conducted in Kathmandu Model Hospital, Kathmandu, Nepal from April to October, 2009. Midstream Urine samples from 1323 patients suspected of UTI were analyzed by microscopy, and conventional semi-quantitative culture technique for the significant growth. Antimicrobial susceptibility test was performed for the isolates by Modified Kirby-Bauer disk diffusion method. Data were analyzed using SPSS software window version 16. The overall prevalence of UTI was found to be 18.89%. The most frequent causative organisms isolated were Escherichia coli (82.30%), Enterococcus faecalis (5.60%), Citrobacter freundii (3.60%), Enterobacter aerogenes (2.40%), Coagulase Negative Staphylococci (2.40%), Pseudomonas aeruginosa (1.20%), Proteus mirabilis (0.8%), Klebsiella pneumoniae (0.4%), and Staphylococcus aureus (0.4%). Nitrofurantoin and Amoxycillin were found to be the most effective antibiotic against gram negative and gram positive isolates respectively. E. coli was found to be the most common etiological agent of UTI and Nitrofurantoin was the most effective drug among the isolates.

Extended-spectrum β-lactamase-producing Enterobacteriaceae: in vitro susceptibility to fosfomycin, nitrofurantoin and tigecycline

OBJECTIVE

To assess the susceptibility trends of community-acquired extended-spectrum β-Iactamase (ESBL)-producing urinary isolates with particular reference to fosfomycin, nitrofurantoin and tigecycline.

MATERIALS AND METHODS

Seven hospitals across the United Arab Emirates participated in this study from June 2008 to March 2010. The antibiotic sensitivity of ESBL-producing uropathogens to a panel of antibiotics including tigecycline, fosfomycin and nitrofurantoin was assessed. The Hyplex ESBL identification system (h-ES-ID) was used for genotypic identification.

RESULTS

Two hundred and ninety-two ESBL-producing Enterobacteriaceae isolates were identified during the study period. Of these, 182 (62%) were urinary isolates and comprised of Escherichia coli: 149 (81.9%), Klebsiella pneumoniae: 30 (16.5%) and Proteus mirabilis: 3 (1.6%). Of the 182 urinary isolates, 179 (98.3%) were from patients with community onset urinary tract infections. The h-ES-ID system identified 172 (94.5%) of the urinary isolates as CTX-M positive. All isolates were susceptible to imipenem and meropenem. Over half of the isolates showed resistance to gentamicin (98; 53.8%), trimethoprim-sulfamethoxazole (139; 76.4%) and ciprofloxacin (143; 78.6%). Sensitivity to nitrofurantoin and fosfomycin was 90 and 100%, respectively. Two CTX-M-positive K. pneumoniae isolates with tigecycline resistance (MIC >4 µg/ml) were identified.

CONCLUSION

There is dissemination of CTX-M ESBL-producing urinary pathogens into the community. Fosfomycin and nitrofurantoin were active against ESBL-positive uropathogens, and emergence of tigecycline resistance needs close monitoring.

Emergence of community-acquired extended-spectrum beta-lactamase Escherichia coli (ESBLEC) in Honolulu: a case series of three individuals with community-acquired ESBLEC bacteriuria

Community-acquired extended-spectrum beta-lactamase E coli (ESBLEC) have not been previously described in Honolulu. Its emergence as a community-acquired pathogen is concerning. This case series describes three patients who were diagnosed with community-acquired ESBLEC bacteriuria in 2010.

Cycloartane triterpenoids from Kleinhovia hospita

Four new cycloartane triterpenoids, together with the known gardenolic acid B, were isolated from Kleinhovia hospita. The triterpenoids (1-3) contain a unique 21,23-diacetal side-chain, while compound 4 contains two alpha,beta-unsaturated ketone moieties. Their structures and relative configurations were determined by spectroscopic methods, including 2D NMR and IR. These compounds showed promising hepatoprotective effects on nitrofurantoin-induced cytotoxicity in human liver-derived Hep G2 cells.

[Etiology of urinary tract infections and antimicrobial susceptibility: a study conducted on a population of children hospitalized in the Department of Pediatrics at Warsaw Bielany Hospital; 2004-2006]

BACKGROUND

the basis of urinary tract infection (UTI) diagnosis in children is based on positive results of microbiological tests. The selection of an antimicrobial drug for empirical treatment and prophylaxis of UTI is determined by the susceptibility of bacterial strains isolated from urine cultures.

AIM

Determination of the etiology of urinary tract infections and drug sensitivity of the pathogen in hospitalized children.

MATERIALS AND METHODS

we performed quantitative analyses of 2522 urine cultures from children admitted to the Department of Paediatrics at Warsaw Bielany Hospital, from January 2004 to December 2006. We obtained 456 positive urinary cultures, which accounted for 18.1% of urinary samples (14.7%; 17.9%; 21.2% in successive years).

RESULTS

in 392 (86%) cases the urinary infection was caused by one of the isolated pathogens: Escherichia coli, Klebsiella spp. or Proteus mirabilis. Escherichia coli was the most frequently isolated pathogen (70-74%). We noted that the frequency of isolating of Klebsiella spp. grew from 6 to 10%, whereas that of Proteus mirabilis fell from 10 to 2% in the same years. Likewise, in the period from 2004-2006 we observed the same level of the susceptibility of Gram-negative bacteria to nitrofurantoin (84-88%) and trimethoprim-sulfamethoxazole (90-91%), whereas we observed a non-statistically significant lowering of susceptibility to aminopenicillins, and aminopenicillins combined with beta-lactamase inhibitors (from 92 to 74%; p=0.2). There was a statistically significant decrease in drug susceptibility to nitrofurantoin (from 86 to 60%; p<0.05). However, because the groups of children treated with nitrofurantoin were small (6-8-11 in successive years) further studies are needed.

CONCLUSION

studies into the etiology of UTI and drug susceptibility of the pathogens in hospitalized children could facilitate correct management of patients receiving empirical treatment and prophylaxis of UTI. Of concern is the noted decrease in the sensitivity of the most frequent pathogen, Escherichia coli, to aminopenicillins and aminopenicillins combined with beta-lactamase inhibitors.

Role of cytochrome P450 reductase in nitrofurantoin-induced redox cycling and cytotoxicity

The one-electron reduction of redox-active chemotherapeutic agents generates highly toxic radical anions and reactive oxygen intermediates (ROI). A major enzyme catalyzing this process is cytochrome P450 reductase. Because many tumor cells highly express this enzyme, redox cycling of chemotherapeutic agents in these cells may confer selective antitumor activity. Nitrofurantoin is a commonly used redox-active antibiotic that possesses antitumor activity. In the present studies we determined whether nitrofurantoin redox cycling is correlated with cytochrome P450 reductase activity and cytotoxicity in a variety of cell lines. Recombinant cytochrome P450 reductase was found to support redox cycling of nitrofurantoin and to generate superoxide anion, hydrogen peroxide, and, in the presence of redox-active iron, hydroxyl radicals. This activity was NADPH dependent and inhibitable by diphenyleneiodonium, indicating a requirement for the flavin cofactors in the reductase. Nitrofurantoin-induced redox cycling was next analyzed in different cell lines varying in cytochrome P450 reductase activity including Chinese hamster ovary cells (CHO-OR) constructed to overexpress the enzyme. Nitrofurantoin-induced hydrogen peroxide production was 16-fold greater in lysates from CHO-OR cells than from control CHO cells. A strong correlation between cytochrome P450 reductase activity and nitrofurantoin-induced redox cycling among the cell lines was found. Unexpectedly, no correlation between nitrofurantoin-induced ROI production and cytotoxicity was observed. These data indicate that nitrofurantoin-induced redox cycling and subsequent generation of ROI are not sufficient to mediate cytotoxicity and that cytochrome P450 reductase is not a determinant of sensitivity to redox-active chemotherapeutic agents.

[Urinary microflora in children from different pediatric departments]

For rational treatment of urinary tract infection it is necessary to know the causative agents. These may be different in various departments of health care institution managing patients with different illnesses. The article presents results of urinary cultures performed in 2002 in Microbiology Laboratory of Vilnius University Children's Hospital. The urine specimens were sent to the Laboratory from all departments of the Hospital. The most common isolate in all departments was E. coli (63.1% of all cultures with growth of >/=10(5) cfu/ml). This organism was somewhat less common in urine specimens obtained from Department of Urology (54.8%); accordingly, species of other organisms were isolated somewhat more often. S. aureus most often was identified in urine specimens from neonatal departments (11.1% of all significant isolates). There were no significant differences in urinary microflora isolated from pediatric in-patients and out-patients. Majority of the strains of the main urinary pathogen, E. coli, showed susceptibility to gentamicin, II-III generation cephalosporins, co-amoxiclav, nitrofurantoin and ciprofloxacin. Thus for empirical treatment of urinary tract infection it is necessary to choose an antibiotic with good activity against E. coli. In more complex circumstances (e.g. in children with urinary tract anomalies and in those treated in intensive care units) it would be better to take into account the results of urinary culture and susceptibility testing.

Ten years surveillance of antimicrobial susceptibility of community-acquired Escherichia coli and other uropathogens in northern Israel (1995-2005)

BACKGROUND

In an era of increasing antimicrobial resistance, knowledge of local antimicrobial susceptibility patterns of common uropathogens is essential for prudent empiric therapy of community-acquired urinary tract infections.

OBJECTIVES

To define antimicrobial susceptibility of Gram-negative uropathogens in northern Israel over a 10 year period and to compare it with patterns of antibiotic use in the same community.

METHODS

We tested the susceptibility of all Gram-negative urinary isolates from outpatients at HaEmek Medical Center over the years 1995, 1999, 2002 and 2005 to common antimicrobial agents. MIC90 of Escherichia coli to some of these agents was determined and antibiotic consumption data over the years 2000-2005 (DDD/1000/day) were obtained.

RESULTS

We observed a rise in susceptibility rates of E. coli to amoxicillin-clavulanate, trimethoprim-sulfamethoxazole and nitrofurantoin and of other Gram-negative isolates to amoxicillin-clavulanate, ceftriaxone and cephalothin. Susceptibility rates of all Gram-negative uropathogens to ciprofloxacin decreased significantly. MIC90 of E. coli for all drugs tested remained stable. There was a significant decrease in the use of nitrofurantoin and TMP-SMX and a significant increase in the use of ampicillin, cephalothin and ceftriaxone.

CONCLUSIONS

Antibiotic resistance patterns mostly remained unchanged or improved slightly. There was, however, a constant decrease in susceptibility of all Gram-negative uropathogens to ciprofloxacin. Antibiotic use patterns could not explain the changes seen in antibiotic susceptibility patterns.

Antimicrobial resistance of urinary tract isolates in acute uncomplicated cystitis among college-aged women: choosing a first-line therapy

OBJECTIVE AND PARTICIPANTS

The authors of this retrospective case study focused on antimicrobial susceptibility of urinary tract isolates in cases of acute uncomplicated cystitis in college-aged women, aged 18 to 24 years, diagnosed at a major south-central university student health center.

METHODS

The authors obtained pertinent data from patient medical and laboratory records, including, diagnoses, urine culture, and susceptibility results.

RESULTS

Of 179 isolates, 161 (90%) were Escherichia coli (E. Coli) isolates, of which 23% were resistant to trimethoprimsulfamethoxazole, <1% were resistant to Ciprofloxacin, and <1% were resistant to nitrofurantoin. Sixty-eight (42%) E. Coli isolates were multidrug resistant. There were 18 isolates cultured in the study group that were significant organisms other than E. coli. For all organisms in the study group, there was a combined resistance rate of 22% to trimethoprim-sulfamethoxazole, <1.0% for Ciprofloxacin, and 7% for nitrofurantoin.

CONCLUSIONS

The findings suggest that both Ciprofloxacin and Nitrofurantoin are acceptable choices for empiric therapy of acute uncomplicated urinary tract infection in this study population, keeping in mind the potential for rising resistance rates to Ciprofloxacin in the community setting.

[Using antibiotics in urinary tract infection in a first level of attention health care unit in Bogotá, Colombia]

OBJECTIVES

Describing using antibiotics for urinary tract infection in a first level of attention health care unit.

METHODS

This was an observational and descriptive study of a cohort of register-based patients attending the Universidad Nacional de Colombia's Health Service Unit (UNISALUD) diagnosed as suffering urinary tract infection between July 2002 and June 2003.

RESULTS

6,3 % urinary tract infection incidence was found, especially affecting women (84,4 %). The signs and symptoms were the same as those usually found in this disease. 58% corresponded to lower tract infection, 36 % to non-specific infection, 4 % to infection during pregnancy and 2 % to upper tract infection. The following uropathogens were isolated: E. coli (88.9%), Proteus spp. (5,1%), Klebsiella spp. (3,7 %), Enterobacter spp. (1%), Citrobacter spp. (1 %) and Staphylococcus saprophyticus (0,3 %). There was great variability in the antibiotic schemes being prescribed. Nitrofurantoin, Trimethoprim-sulfamethoxizole and Fluoroquinolones were the most prescribed, per defined daily dose; these antibiotics presented low susceptibility for the uropathogens so isolated. There was a 4:1 ratio of empirical treatment respecting confirmed ones. 98 % of the cases corresponded to patients suffering from a single event or having just 1 to 2 recurrences. DISCUSSION The urinary tract infection studied here presented a similar epidemiological profile to that usually found in the general population. The isolated microorganism's low susceptibility to the prescribed antibiotics could reflect inappropriate use of antibiotics by the health service, inducing selective pressure on bacterial resistance.

Comparison of Essential Oils from Three Plants for Enhancement of Antimicrobial Activity of Nitrofurantoin against Enterobacteria

BACKGROUND

Piperitone from plant essential oils enhancesbactericidal activities of nitrofurantoin and furazolidone against bacteria from the family Enterobacteriaceae. In this study, the essential oils of spearmint (Mentha spicata L.), dill (Anethum graveolens L.) and peppermint (Mentha piperita L.)were screened for augmentation of nitrofurantoin activity and the most active components were determined.

METHOD

The effects of essential oils and their components on the bactericidal activity of nitrofurantoin against Enterobacter cloacae were studied using disk-diffusion and agar-dilution methods. The composition of essential oils was studied using gas chromatography-mass spectrometry.

RESULTS

M. spicata and A. graveolens oils exhibited the highest effects. Gas chromatography-mass spectrometry analysis showed that the oils of these two plants contained 40.12 and 20.32% carvone, respectively. Pure carvone and piperitone equally increased the bactericidal activity of nitrofurantoin. Other ingredients of essential oils, including camphor, limonene and menthone, were less effective.

Illegal use of nitrofurans in food animals: Contribution to human salmonellosis?

Recent observations in Portugal of a remarkable incidence (65%) of Salmonella isolates from several sources (predominantly human and poultry) with decreased susceptibility to nitrofurantoin (MIC > or =64 mg/L), mostly comprising serogroup D isolates of Salmonella Enteritidis belonging to different phage types, suggest that illegal use of nitrofurans, especially in the poultry industry, might have contributed to the selection and prevalence of S. Enteritidis in food animals, and consequently to human salmonellosis in Portugal. Indiscriminate use of nitrofurans might also be implicated in the emergence of two multiresistant Salmonella Typhimurium clones disseminated throughout the country.

A TLC bioautographic assay for the detection of nitrofurantoin resistance reversal compound

A simple TLC bioautographic method was developed for detection of antibiotic resistance reversal agents. In this study, the retention factor values of the components of some essential oils not previously shown to have any antibacterial activity were evaluated on nitrofurantoin supplemented agar media. The active component of Artemisia annua, Artemisia dracunculus and Eucalyptus globulus essential oils was piperitone which increased the antibacterial activity of nitrofurantoin against Enterobacter cloacae. Piperitone was not detected in the essential oil of Humulus lupulus and we could not observe any clear areas in this bioautographic method.