Ciprofloxacin Exposure Research Articles

Ciprofloxacin Exposure Leading to Fatal Hepatotoxicity: An Unusual Correlation.

Patient: Female, 74Final Diagnosis: Acute drug-induced liver failureSymptoms: Anorexia • fatigue • nausea • vomitingMedication: —Clinical Procedure: —Specialty: Gastroenterology and HepatologyObjective:Challenging differential diagnosisBackground:Ciprofloxacin is a commonly used fluoroquinolone antibiotic. It is occasionally associated with benign elevations in liver enzymes. Few reports in the literature correlate ciprofloxacin with significant liver injury. We present a fatal case of ciprofloxacin-induced liver failure.Case Report:A 74-year-old female was successfully treated with ciprofloxacin for a urinary tract infection (UTI), but immediately began having new-onset symptoms, including fatigue and nausea. This continued for two months, at which time she presented to the hospital; she was found to have elevated liver enzymes and another UTI. She was treated with ciprofloxacin again for UTI and discharged three days later, following mild improvement. One week later, she returned to another hospital and was found to have more significantly elevated liver function tests and jaundice. Extensive viral and autoimmune panels were unremarkable. Liver biopsy showed cholestatic hepatitis of unclear etiology. The patient was discharged again following a mild decline in liver enzymes. Soon after, the patient was admitted to our institution with similar complaints. Serum transaminases remained elevated, with an increase in alkaline phosphatase and bilirubin. The Council for International Organizations of Medical Sciences/the Roussel Uclaf Causality Assessment Method (CIOMS/RUCAM) scale was found to be 8, outlining a high or definite probability that the ciprofloxacin was the cause of the patient’s hepatotoxicity. A one-week course of prednisone for possible hypersensitivity reaction was tried; however, it proved unsuccessful. Palliative care was consulted, and the patient passed away shortly thereafter.Conclusions:This case demonstrates the potential for liver failure from ciprofloxacin. Clinicians should evaluate the possibility of ciprofloxacin-induced hepatotoxicity in a patient presenting with liver injury of unknown etiology. Similarly, it is important to consider this significant effect when a practitioner considers antibiotic choice.

Effect of Sucralfate on the Relative Bioavailability of Enrofloxacin and Ciprofloxacin in Healthy Fed Dogs.

BackgroundSucralfate impairs absorption of ciprofloxacin and other fluoroquinolones in humans, but no sucralfate–fluoroquinolone interaction has been reported in dogs. Veterinary formularies recommend avoiding concurrent administration of these medications, which might impact compliance, therapeutic success, and resistance selection from fluoroquinolones.ObjectivesTo determine whether a drug interaction exists when sucralfate is administered to fed dogs concurrently with ciprofloxacin or enrofloxacin, and whether a 2 hour delay between fluoroquinolone and sucralfate affects fluoroquinolone absorption.AnimalsFive healthy Greyhounds housed in a research colony.MethodsThis was a randomized crossover study. Treatments included oral ciprofloxacin (C) or oral enrofloxacin (E) alone, each fluoroquinolone concurrently with an oral suspension of sucralfate (CS, ES), and sucralfate suspension 2 hours after each fluoroquinolone (C2S, E2S). Fluoroquinolone concentrations were evaluated using liquid chromatography with mass spectrometry.ResultsDrug exposure of ciprofloxacin was highly variable (AUC 5.52–22.47 h μg/mL) compared to enrofloxacin (AUC 3.86–7.50 h μg/mL). The mean relative bioavailability for ciprofloxacin and concurrent sucralfate was 48% (range 8–143%) compared to ciprofloxacin alone. Relative bioavailability of ciprofloxacin improved to 87% (range 37–333%) when sucralfate was delayed by 2 hours. By contrast, relative bioavailability for enrofloxacin and concurrent sucralfate was 104% (94–115%).Conclusions and Clinical ImportanceA possible clinically relevant drug interaction for the relative bioavailability of ciprofloxacin with sucralfate was found. No significant difference in bioavailability was documented for enrofloxacin with sucralfate. Further research is warranted in fasted dogs and clinical cases requiring enrofloxacin or other approved fluoroquinolones in combination with sucralfate.

Effect of Multi Drug Resistance Protein 4 (MRP4) Inhibition on the Pharmacokinetics and Pharmacodynamics of Ciprofloxacin in Normal and Rats with LPS-Induced Inflammation.

Infection and inflammation are known to cause wide variability in disposition of drugs through modulation of drug transporters. However, the effects of inhibition of multidrug resistance protein 4 (MRP4) on pharmacokinetics and pharmacodynamics are poorly understood in normal and inflamed conditions. We hypothesized that inflammation alters the pharmacokinetic parameters of ciprofloxacin; and Pharmacokinetic/Pharmacodynamic indices, such as ratio of peak plasma concentration to minimum inhibitory concentration (C max/MIC) and ratio of area under the plasma drug concentration-time curve to minimum inhibitory concentration (AUC/MIC) of ciprofloxacin will be improved with the co-administration of a MRP4 inhibitor, dipyridamole, in inflammatory conditions. In this study, the role of MRP4 on the pharmacokinetic and pharmacodynamic parameters of ciprofloxacin was investigated by the co-administration of dipyridamole in rats with or without lipopolysaccharide (LPS)-induced inflammation. The pharmacokinetic parameters for ciprofloxacin were calculated by non-compartmental approach. MIC of ciprofloxacin was determined using broth microdilution technique. Induction of inflammation in rats resulted in marked reduction in C max and AUC; and an increase in the volume of distribution (V d/F) and clearance (Cl/F) of ciprofloxacin, compared to normal rats. Co-administration of dipyridamole with ciprofloxacin in inflamed rats resulted in a threefold increase in AUC, a twofold decrease in V d/F and a threefold decrease in Cl/F of ciprofloxacin with significantly prolonged half-life compared to inflamed rats who received ciprofloxacin alone. Co-administration of dipyridamole enhanced AUC/MIC values of ciprofloxacin in both normal and inflamed rats. The results suggest that MRP4 inhibition increases the systemic exposure of ciprofloxacin in both normal and inflammatory conditions.

Genetic analysis of Escherichia coli RadA: functional motifs and genetic interactions.

The RadA/Sms protein is a RecA-related protein found universally in eubacteria and plants, implicated in processing of recombination intermediates. Here we show that the putative Zn finger, Walker A motif, KNRXG motif and Lon protease homology domain of the Escherichia coli RadA protein are required for DNA damage survival. RadA is unlikely to possess protease activity as the putative active site serine is not required. Mutants in RadA have strong synergistic phenotypes with those in the branch migration protein RecG. Sensitivity of radA recG mutants to azidothymidine (AZT) can be rescued by blocking recombination with recA or recF mutations or by overexpression of RuvAB, suggesting that lethal recombination intermediates accumulate in the absence of RadA and RecG. Synthetic genetic interactions for survival to AZT or ciprofloxacin exposure were observed between RadA and known or putative helicases including DinG, Lhr, PriA, Rep, RuvAB, UvrD, YejH and YoaA. These represent the first affected phenotypes reported for Lhr, YejH and YoaA. The specificity of these effects sheds new light on the role of these proteins in DNA damage avoidance and repair and implicates a role in replication gap processing for DinG and YoaA and a role in double-strand break repair for YejH.

Shape does matter: short high-concentration exposure minimizes resistance emergence for fluoroquinolones in Pseudomonas aeruginosa.

For fluoroquinolones, the area under the free plasma concentration-time curve divided by the MIC (fAUC/MIC) best predicts bacterial killing in mice and outcomes in patients. However, it is unknown whether the shape of the antibiotic concentration profile affects resistance emergence. Our objective was to compare killing and resistance between ciprofloxacin concentration profiles with different shapes at the same fAUC/MIC and identify the durations of ciprofloxacin exposure that minimize resistance emergence. Static time-kill studies over 24 h using Pseudomonas aeruginosa ATCC 27853 assessed fAUC/MIC of 44 and 132 of ciprofloxacin (MICCIP = 0.25 mg/L) and fAUC/MIC of 22, 44 and 132 of ciprofloxacin plus an efflux pump inhibitor (MICCIP+EPI = 0.031 mg/L) at initial inocula of 10(4), 10(5) and 10(6) cfu/mL. Ciprofloxacin was added at 0 h and rapidly removed at 1, 4, 10, 16 or 24 h. Mutant frequencies and MICs were determined at 24 h. High ciprofloxacin concentrations over 1-10 h yielded more rapid and extensive initial killing compared with 16 and 24 h exposures at the same fAUC/MIC. No resistance emerged for 1-10 h exposures, although regrowth of susceptible bacteria was extensive. Ciprofloxacin exposure over 24 h yielded less regrowth, but ciprofloxacin-resistant bacteria at 5× MIC amplified by over 5 log10 and almost completely replaced the susceptible bacteria by 24 h; MICs increased 4- to 8-fold. Resistance also emerged on 3× MIC, but not 5× MIC, plates when efflux was inhibited. Pre-existing resistant subpopulations amplified extensively with 24 and 16 h exposures, but not with shorter durations. The shape of the ciprofloxacin concentration profile was critical to minimize resistance emergence.

Toxicity of ciprofloxacin and sulfamethoxazole to marine periphytic algae and bacteria

Ciprofloxacin and sulfamethoxazole are two antibiotics commonly detected in the aquatic environment, but information on their toxicity towards natural microbial communities is largely absent. In particular no data are available for marine microorganisms. The aim of the current study was therefore to evaluate the chronic toxicity of ciprofloxacin and sulfamethoxazole to natural marine biofilms (periphyton), a complex ecological community comprising a variety of bacterial and algal species. The biofilms were sampled along the Swedish west coast and subsequently exposed over 4 days in a semi-static system to a concentration series of each antibiotic.Effects on the bacterial part of the periphyton community were assessed using Biolog Ecoplates, reflecting total respiration and functional diversity of the bacterial community. Exposure to either antibiotic resulted in a clear concentration–response relationship with EC10 and EC50 values for the inhibition of total carbon source utilization of 46.1nmol/L and 490.7nmol/L for ciprofloxacin, and 56nmol/L and 1073nmol/L for sulfamethoxazole. The NOEC for ciprofloxacin was 26nmol/L, with a minimum significant difference of 19.24%, for sulfamethoxazole it was 140nmol/L with a minimum significant difference of 14%. Multivariate data exploration of the whole carbon source utilization pattern confirmed these results. The data indicate that sulfamethoxazole leads to a general decrease in carbon source utilization, while ciprofloxacin exposure leads to a re-arrangement of the carbon-utilization pattern in the region of 20– 50% effect. This corresponds with the higher specificity of ciprofloxacin for certain bacterial species.Effects on the algal part of the communities were evaluated by analyzing the amount and composition of photosynthetic pigments, and neither ciprofloxacin nor sulfamethoxazole caused any inhibitory effects up to the maximum tested concentration of 9000nmol/L. However, sulfamethoxazole exposure did lead to a significant stimulation (75% above control level) of the total pigment content of the biofilm already at the lowest tested concentration of 5nmol/L. The stimulation then decreased with increasing concentrations to finally return to control level at 3000nmol/L. No shifts in the relative pigment composition were observed, indicating a generally increased algal biomass without major shifts in community composition.

Structural changes and differentially expressed genes in Pseudomonas aeruginosa exposed to meropenem-ciprofloxacin combination.

The effect of a meropenem-ciprofloxacin combination (MCC) on the susceptibility of multidrug-resistant (MDR) Pseudomonas aeruginosa (MRPA) clinical isolates was determined using checkerboard and time-kill curve techniques. Structural changes and differential gene expression that resulted from the synergistic action of the MCC against one of the P. aeruginosa isolates (1071-MRPA]) were evaluated using electron microscopy and representational difference analysis (RDA), respectively. The differentially expressed, SOS response-associated, and resistance-associated genes in 1071-MRPA exposed to meropenem, ciprofloxacin, and the MCC were monitored by quantitative PCR. The MCC was synergistic against 25% and 40.6% of MDR P. aeruginosa isolates as shown by the checkerboard and time-kill curves, respectively. The morphological and structural changes that resulted from the synergistic action of the MCC against 1071-MRPA were a summation of the effects observed with each antimicrobial alone. One exception included outer membrane vesicles, which were seen in a greater amount upon ciprofloxacin exposure but were significantly inhibited upon MCC exposure. Cell wall- and DNA repair-associated genes were differentially expressed in 1071-MRPA exposed to meropenem, ciprofloxacin, and the MCC. However, some of the RDA-detected, resistance-associated, and SOS response-associated genes were expressed at significantly lower levels in 1071-MRPA exposed to the MCC. The MCC may be an alternative for the treatment of MDR P. aeruginosa. The effect of this antimicrobial combination may be not only the result of a summation of the effects of meropenem and ciprofloxacin but also a result of differential action that likely inhibits protective mechanisms in the bacteria.

Quinolone-resistant Escherichia coli from the faecal microbiota of healthy volunteers after ciprofloxacin exposure are highly adapted to a commensal lifestyle

Quinolone-resistant Escherichia coli (QREC) primarily emerge in commensal bacteria under selective pressure. The aim of this work was to investigate the characteristics of QREC from the faecal microbiota after quinolone exposure, as they remain largely unknown. Forty-eight healthy volunteers received ciprofloxacin from day 1 to day 14. QREC were detected in stools from 14 subjects at day 42. QREC were compared in terms of genetic background, metabolic properties, stress resistance and intestinal colonization abilities with quinolone-susceptible E. coli (QSEC) from the same 14 individuals and from 29 volunteers who remained QREC-free. QREC always belonged to a single clone for a given volunteer and to restricted phylogenetic groups. QREC carried significantly more iron capture systems than QSEC. Maximum growth rates in minimal medium with gluconate, general stress regulator RpoS activity assessed by iodine staining and resistance to oxidative and acid stresses were significantly higher for QREC than for QSEC. In a mouse colonization model, QREC efficiently colonized the intestine microbiota despite the presence of QSEC competitors. At day 42, QREC and QSEC faecal counts from the 14 volunteers were comparable except in three subjects where only QREC could be detected. These results suggest that QREC do not have a fitness cost, probably as a result of genetic co-selection, but are highly adapted to a commensal lifestyle. They may not be eliminated easily from the faecal microbiota from healthy subjects once selected.

Effect of ciprofloxacin exposure on DNA repair mechanisms in Campylobacter jejuni

Ciprofloxacin resistance is common both among animal and human Campylobacter jejuni isolates. Resistant isolates are shown to persist even without selection pressure. To obtain further insight on effects of ciprofloxacin exposure on C. jejuni we compared transcriptional responses of both C. jejuni wild-type strain 81-176 (ciprofloxacin MIC 0.125 mg l(-1)) and its intermediate ciprofloxacin-resistant variant P3 (Asp90→Asn in GyrA) in the absence and presence of ciprofloxacin. Further, we sequenced the genome of P3 and compared the sequence with that of wild-type 81-176. One hour of exposure to 8 mg l(-1) of ciprofloxacin did not decrease the viability of the parent strain 81-176. Transcriptional analysis revealed that ciprofloxacin exposure caused changes in the expression of genes involved in DNA replication and repair. While in the wild-type the exposure caused downregulation of several genes involved in the control of DNA replication and recombination, the genes controlling nucleotide excision repair and DNA modification were upregulated in both the wild-type and P3. In addition, we observed that ciprofloxacin exposure caused upregulation of genes responsible for damage recognition in base excision repair in P3. In contrast, without ciprofloxacin exposure, DNA repair mechanisms were substantially downregulated in P3. The genome sequence of P3 compared to that of the 81-176 parental strain had three non-synonymous substitutions and a deletion, revealing that the resistant variant had maintained genetic integrity. In conclusion, enhanced DNA repair mechanisms under ciprofloxacin exposure might explain maintenance of genomic integrity in ciprofloxacin-resistant variant P3.

Characterization of the Burkholderia thailandensis SOS response by using whole-transcriptome shotgun sequencing.

The bacterial SOS response is a well-characterized regulatory network encoded by most prokaryotic bacterial species and is involved in DNA repair. In addition to nucleic acid repair, the SOS response is involved in pathogenicity, stress-induced mutagenesis, and the emergence and dissemination of antibiotic resistance. Using high-throughput sequencing technology (SOLiD RNA-Seq), we analyzed the Burkholderia thailandensis global SOS response to the fluoroquinolone antibiotic, ciprofloxacin (CIP), and the DNA-damaging chemical, mitomycin C (MMC). We demonstrate that a B. thailandensis recA mutant (RU0643) is ∼4-fold more sensitive to CIP in contrast to the parental strain B. thailandensis DW503. Our RNA-Seq results show that CIP and MMC treatment (P < 0.01) resulted in the differential expression of 344 genes in B. thailandensis and 210 genes in RU0643. Several genes associated with the SOS response were induced and include lexA, uvrA, dnaE, dinB, recX, and recA. At the genome-wide level, we found an overall decrease in gene expression, especially for genes involved in amino acid and carbohydrate transport and metabolism, following both CIP and MMC exposure. Interestingly, we observed the upregulation of several genes involved in bacterial motility and enhanced transcription of a B. thailandensis genomic island encoding a Siphoviridae bacteriophage designated E264. Using B. thailandensis plaque assays and PCR with B. mallei ATCC 23344 as the host, we demonstrate that CIP and MMC exposure in B. thailandensis DW503 induces the transcription and translation of viable bacteriophage in a RecA-dependent manner. This is the first report of the SOS response in Burkholderia spp. to DNA-damaging agents. We have identified both common and unique adaptive responses of B. thailandensis to chemical stress and DNA damage.

Comparative Genome Analysis of Ciprofloxacin-ResistantPseudomonas aeruginosaReveals Genes Within Newly Identified High Variability Regions Associated With Drug Resistance Development

The alarming rise of ciprofloxacin-resistant Pseudomonas aeruginosa has been reported in several clinical studies. Though the mutation of resistance genes and their role in drug resistance has been researched, the process by which the bacterium acquires high-level resistance is still not well understood. How does the genomic evolution of P. aeruginosa affect resistance development? Could the exposure of antibiotics to the bacteria enrich genomic variants that lead to the development of resistance, and if so, how are these variants distributed through the genome? To answer these questions, we performed 454 pyrosequencing and a whole genome analysis both before and after exposure to ciprofloxacin. The comparative sequence data revealed 93 unique resistance strain variation sites, which included a mutation in the DNA gyrase subunit A gene. We generated variation-distribution maps comparing the wild and resistant types, and isolated 19 candidates from three discrete resistance-associated high variability regions that had available transposon mutants, to perform a ciprofloxacin exposure assay. Of these region candidates with transposon disruptions, 79% (15/19) showed a reduction in the ability to gain high-level resistance, suggesting that genes within these high variability regions might enrich for certain functions associated with resistance development.

Fluoroquinolone associated myasthenia gravis exacerbation: clinical analysis of 9 cases

To explore the characteristics of acute exacerbations of myasthenia gravis after fluoroquinolone exposure. Gender, age, prior type, absolute score, concurrent disease, precipitated disease, use of antibiotic, onset/symptom/degree of exacerbation, therapeutic measures and prognosis at Month 1 were retrospectively analyzed for 9 patients after fluoroquinolone systemic exposure. Ciprofloxacin (n = 4), levofloxacin (n = 1) and moxifloxacin (n = 4) exposure resulted in myasthenia gravis exacerbation. Myasthenia gravis exacerbations developed at 15 minutes to 4 days post-exposure. And the clinical scores of quantitative myasthenia gravis (QMG) increased by an average of 10. The main syndromes included dyspnea, diplopia, ptosis and dysphagia. All patients improved upon the withdrawal of fluoroquinolone in conjunctions with other interventions. Fluoroquinolone exposure may result in myasthenia gravis exacerbations in patients with underlying diseases. Healthcare professionals should be aware of this serious drug-disease association.

Antimicrobial resistance and co-selection phenomenon in Listeria spp. recovered from food and food production environments

Antimicrobial resistance (AMR), co-selection phenomenon, and the relationship between reduced susceptibility (RSC) to ciprofloxacin (CIP) and resistance to other antimicrobials in Listeria spp. (n = 103) recovered from food processing environments (FPE) and food were investigated. Resistance of Listeria monocytogenes and other listeriae, respectively, to cefoxitin (FOX; 98% vs. 88%), CIP (7% vs. 4%), clindamycin (CLI; 33% vs. 59%) and tetracycline (6% vs. 8%) was observed, as was RSC to CIP (67% vs. 57%) and CLI (65% vs. 41%). L. monocytogenes also possessed RSC to linezolid (LZD; 6%), rifampicin (2%) and streptomycin (6%), with other listeriae displaying RSC to chloramphenicol (4%). L. monocytogenes serotype 1/2a (90%) isolates were more frequently resistant or possessed RSC to CIP compared to serotype 4b (55%) (p = 0.015). When eight strains were experimentally adapted to high concentrations of CIP, co-selection occurred as MICs to benzalkonium chloride (BAC) increased (n = 5), gentamicin MICs remained the same (n = 6) or increased 2-fold (n = 2), and led to RSC to LZD (n = 1) and resistance to CLI (n = 8). Overall, levels of resistance/RSC to CIP in food chain isolates, particularly 1/2a, are concerning. Further, reduced sensitivity to disparate antimicrobials following CIP exposure highlights the need for increased knowledge of co-selection phenomenon linked with antimicrobial agents.

Systemic Exposure, Tissue Distribution, and Disease Evolution of a High Solubility Ciprofloxacin–Aluminum Complex in a Murine Model of Septicemia Induced bySalmonella entericaSerotype Enteritidis

A new pharmaceutical derivative obtained by stoichiometric complexation of ciprofloxacin (CIP) with aluminum (CIP-complex) has been investigated and reported in this study. Such product has high solubility in the gastrointestinal pH range and was successful in the development of optimized formulations while maintaining its antimicrobial potency. The systemic exposure, tissue distribution, and the disease evolution after given CIP-complex were assessed. The systemic exposure and distribution in intestines, lungs, and kidneys after a single intragastric administration of CIP-complex and CIP given alone, used as reference, were performed in Balb-C mice at a dose of 5 mg CIP/kg. For the assessment of the disease evolution assay, mice were infected with a virulent strain of Salmonella enterica serotype Enteritidis and treated intragastrically once or twice daily during 5 consecutive days with solutions of CIP-complex or the reference. Clinical follow up and survival was measured during 15 days post inoculation and health state was scored during this period from 0 to 5. CIP-complex showed a 32% increase in C(max), an earlier T(max), and a smaller AUC(0-12) than the reference. Maximum tissue concentrations (0.5-1 h) were significantly higher in CIP-complex (447% in intestine, 93% in kidney, and 44% in lungs). In the infection model used in this study, survival in CIP-complex versus CIP groups was 40% versus 20% (twice-daily administration) and 30% versus 0% (once-daily administration). Health state of the survivors of CIP-complex group (5/5) was higher than CIP group (3/5). The greater effectiveness of CIP-complex is attributed to the higher levels of CIP in the intestine. Our results supported the fact that CIP-complex is a promising candidate to develop dose-efficient formulations of CIP for oral administration.

DRESS syndrome following ciprofloxacin exposure: An unusual association

Patient: Female, 24Final Diagnosis: DRESS syndromeSymptoms: Fever • rash • facial and body swelling • muscular pain • diarrheaMedication: CiprofloxacinClinical Procedure: —Specialty: Internal Medicine • HematologyObjective:Unusual or unexpected effect of treatmentBackground:Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) is a rare, potentially life-threatening drug reaction with a mean latency period of 3.9 weeks. It has been described in association with many medications; yet, Ciprofloxacin was reported once in literature to be the offending drug. We are presenting a rare case of Ciprofloxacin-induced DRESS syndrome with symptom onset 2 days after exposure.Case Report:A 24-year-old female presented with symptoms suggestive of UTI and was prescribed Ciprofloxacin. Two days later she started to complain of fever, diffuse rash, swelling of her face, arms and flanks, watery diarrhea and muscular pain. Five days after symptom onset she presented to our institution with WBC count 38,810 cells/μL and absolute Eosinophil count 17,080 cell/μL. Peripheral blood smear showed immature Eosinophilic myelocytes and metamyelocytes. Skin biopsy showed superficial perivascular lymphocytic infiltration with dermal edema. Further workup was negative for parasitic infestations, HIV and viral hepatitis, allergic diseases, hematologic and non-hematologic malignancies, vasculitides and autoimmune processes. Ciprofloxacin was discontinued upon admission and the patient started to improve quickly. Patient was followed in clinic after 3 weeks and was completely asymptomatic with WBC count 7,250 cell/μL and absolute Eosinophil count 2,900 cell/μL.Conclusions:DRESS syndrome is a possible complication of Ciprofloxacin treatment that clinicians should consider. Shorter latency period might be a unique feature of Fluoroquinolone-induced DRESS syndrome. According to RegiSCAR scoring system, our case is categorized as (probable) with a score of (4). In fact, the vast majority of reported cases are classified as (probable/definite).

Microfluidic Device for Controllable Chemical Release via Field‐Actuated Membrane Incorporating Nanoparticles

We report a robust magnetic‐membrane‐based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl‐iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose‐response relationship, which shows promise in providing significant guidance for on‐demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

Cure of Filament-Caused MBR Fouling in the Presence of Antibiotics: Taking Ciprofloxacin Exposure As an Example

Pharmaceuticals and personal care products (PPCPs) are ubiquitous in wastewater streams, but little is known regarding their roles in membrane fouling during the operation of membrane bioreactors (MBRs). This study attempted to understand the role of ciprofloxacin exposure in control of filamentous bulking as well as membrane fouling mitigation. Compared with the control MBR, results show that the ciprofloxacin could selectively inhibit and kill filaments present in the mixed liquor, and, as a consequence, the sludge settleability improved significantly. The addition of ciprofloxacin had little influence on organic removals and nitrification, but had an adverse effect on denitrification. In addition, the sludge flocs exposure to ciprofloxacin still kept in compact structure; specifically, granular sludge was finally formed possibly due to the increase of polysaccharides in extracellular polymeric substances (EPS). Characterization by nuclear magnetic resonance (NMR) corroborated the enrichment of polysaccharides in the EPS exposure to ciprofloxacin. On the other hand, because of the release of EPS and the decay of filaments, soluble microbial products (SMP), particularly soluble polysaccharides, increased significantly in the MBR exposure to ciprofloxacin. Despite this, the results of this study show that the presence of trace contaminants in wastewater streams may play some positive roles in MBR fouling control.

Involvement of the Lon Protease in the SOS Response Triggered by Ciprofloxacin in Pseudomonas aeruginosa PAO1

Pseudomonas aeruginosa PAO1 lon mutants have phenotypes of deficiencies in cell division, swarming, twitching, and biofilm formation as well as a phenotype of ciprofloxacin supersusceptibility. In this study, we demonstrated that a lon mutant was also supersensitive to the DNA-damaging agent UV light. To understand the influence of lon in causing these phenotypes, global gene expression was characterized by performing microarrays on the lon mutant and the PAO1 wild type grown in the presence of subinhibitory concentrations of ciprofloxacin. This revealed major differences in the expression of genes involved in the SOS response and DNA repair. Real-time quantitative PCR confirmed that these genes were highly upregulated upon ciprofloxacin exposure in the wild type but were significantly less induced in the lon mutant, indicating that Lon modulates the SOS response and consequentially ciprofloxacin susceptibility. As the known Lon target SulA is a member of the SOS response regulon, the influence of mutating or overexpressing this gene, and the negative regulator of the SOS response, LexA, was examined. Overexpression of lexA had no effect on the Lon-related phenotypes, but sulA overexpression recapitulated certain lon mutant phenotypes, including altered motility and cell division, indicating that Lon regulates these phenotypes through SulA. However, sulA overexpression did not affect ciprofloxacin susceptibility or biofilm formation, indicating that these properties were independently determined. Lon protease was also demonstrated to strongly influence RecA protein accumulation in the presence of ciprofloxacin. A model of DNA repair involving the Lon protease is proposed.

Antibiotic resistance profiles of representative wetland bacteria and faecal indicators following ciprofloxacin exposure in lab-scale constructed mesocosms

In this study, the effect of the antibiotic ciprofloxacin on the presentation and potential development of antibiotic resistance among selected faecal indicators ( Escherichia coli and Enterococcus spp.) and the intrinsic bacterial community for a freshwater model ecosystem was investigated. Four parallel mesocosm wetlands planted with Phragmites australis were initially seeded with an activated sludge inoculum from a wastewater treatment plant and monitored over the course of 63 days. Two of the four mesocosms (CIP1 and CIP2) were initially exposed to a ciprofloxacin concentration of 2 μg mL −1 for a 5 day period, and two were considered controls (CON1 and CON2). Minimum inhibitory concentrations were determined for the culturable interstitial microbial community using ciprofloxacin concentrations ranging from 0.5 to 16 μg mL −1 and compared with total heterotrophic plate counts (HPCs). E. coli and Enterococcus spp. were enumerated and screened for antimicrobial resistance to twelve different antibiotics both before and after mesocosm ciprofloxacin exposure. Concentrations for total heterotrophs within the interstitial water were in the order of 10 6–10 8 CFU 100 mL −1, while E. coli and Enterococcus spp. were present in lower concentrations, at 10 2–10 3 CFU 100 mL −1. All four mesocosms had the same minimum inhibitory concentrations (MICs) of 2 μg mL −1 for total heterotrophic community during the first week of start-up (before ciprofloxacin exposure), followed by a sharp increase in ciprofloxacin exposed mesocosms on day 14 (after ciprofloxacin exposure), reaching a maximum MIC of 16 μg mL −1. The resistance levels of interstitial heterotrophic counts determined by the agar dilution method peaked 7 days following the ciprofloxacin exposure, and decreased thereafter. A significant increase ( p < 0.05) to the following antibiotics was observed among E. coli following ciprofloxacin exposure within mesocosm CIP2: ciprofloxacin (CIP), chloramphenicol (C), cefotaxime (CTX), ceftriaxone (CRO), and doxycycline (D). These results illustrate the potential for a single antibiotic exposure event to create a noticeable increase in the antibiotic resistance profile, not only to the imposed antibiotic, but to other classes of antibiotics. The initial background levels of resistance among Enterococcus spp. were significantly higher than those observed among E. coli, exhibiting a combined average of 96%, 96%, and 100% resistance to ciprofloxacin (CIP), linezolid (LZD), and streptomycin (S), respectively. Following the addition of ciprofloxacin, Enterococcus spp. retained high levels of resistance to ciprofloxacin, linezolid, and streptomycin, with a significant increase ( p < 0.05) to vancomycin (VA), reaching 100% on Day 63. The findings of this study suggest that the transient presence of an isolated exposure event of ciprofloxacin can impact the antibiotic resistance profiles among faecal indicators in lab-scale constructed mesocosms and has the potential to impact constructed wetland treatment systems.

The TCA cycle is not required for selection or survival of multidrug-resistant Salmonella

The initial aim of this study was to use a systems biology approach to analyse a ciprofloxacin-selected multidrug-resistant (MDR) Salmonella enterica serotype Typhimurium, L664. The whole genome sequence and transcriptome of L664 were analysed. Site-directed mutagenesis to recreate each mutation was carried out, followed by phenotypic characterization and mutation frequency analysis. As a mutation in the TCA cycle was detected we tested the controversial hypothesis regarding the bacterial response to bactericidal antibiotics, put forward by Kohanski et al. (Cell 2007; 130: 797-810 and Mol Cell 2010; 37: 311-20), that exposure of bacteria to agents such as ciprofloxacin produces reactive oxygen species (ROS), which transiently increase the mutation rate giving rise to MDR bacteria. L664 contained a mutation in ramR that conferred MDR. A mutation in tctA affected the TCA cycle and conferred the inability to grow on minimal agar. The virulence of L664 was not attenuated. Ciprofloxacin exposure produced ROS in L664 and SL1344 (tctA::aph), but it was reduced and occurred later. There were no significant differences in the rates of killing or mutations per generation to antibiotic resistance between the strains. Whilst we confirm production of ROS in response to ciprofloxacin, we have no data to support the hypothesis that this leads to selection of MDR strains. Our results indicate that the mutations in tctA and glgA were random as they did not pre-exist in the parental strain, and that the mutation in tctA did not provide a survival advantage or disadvantage in the presence of antibiotic.