Nitrofurazone Removal from Water Enhanced by Coupling Photocatalysis and Biodegradation.

(1) Background: Environmental contamination with antibiotics is particularly serious because the usual methods used in wastewater treatment plants turn out to be insufficient or ineffective. An interesting idea is to support natural biodegradation processes with physicochemical methods as well as with bioaugmentation with efficient microbial degraders. Hence, the aim of our study is evaluation of the effectiveness of different methods of nitrofurazone (NFZ) degradation: photolysis and photodegradation in the presence of two photocatalysts, the commercial TiO2-P25 and a self-obtained Fe3O4@SiO2/TiO2 magnetic photocatalyst. (2) Methods: The chemical nature of the photocatalysis products was investigated using a spectrometric method, and then, they were subjected to biodegradation using the strain Achromobacter xylosoxidans NFZ2. Additionally, the effects of the photodegradation products on bacterial cell surface properties and membranes were studied. (3) Results: Photocatalysis with TiO2-P25 allowed reduction of NFZ by over 90%, demonstrating that this method is twice as effective as photolysis alone. Moreover, the bacterial strain used proved to be effective in the removal of NFZ, as well as its intermediates. (4) Conclusions: The results indicated that photocatalysis alone or coupled with biodegradation with the strain A. xylosoxidans NFZ2 leads to efficient degradation and almost complete mineralization of NFZ.

A Case of Phage Therapy against Pandrug-Resistant Achromobacter xylosoxidans in a 12-Year-Old Lung-Transplanted Cystic Fibrosis Patient.

Bacteriophages are a promising therapeutic strategy among cystic fibrosis and lung-transplanted patients, considering the high frequency of colonization/infection caused by pandrug-resistant bacteria. However, little clinical data are available regarding the use of phages for infections with Achromobacter xylosoxidans. A 12-year-old lung-transplanted cystic fibrosis patient received two rounds of phage therapy because of persistent lung infection with pandrug-resistant A. xylosoxidans. Clinical tolerance was perfect, but initial bronchoalveolar lavage (BAL) still grew A. xylosoxidans. The patient's respiratory condition slowly improved and oxygen therapy was stopped. Low-grade airway colonization by A. xylosoxidans persisted for months before samples turned negative. No re-colonisation occurred more than two years after phage therapy was performed and imipenem treatment was stopped. Whole genome sequencing indicated that the eight A. xylosoxidans isolates, collected during phage therapy, belonged to four delineated strains, whereby one had a stop mutation in a gene for a phage receptor. The dynamics of lung colonisation were documented by means of strain-specific qPCRs on different BALs. We report the first case of phage therapy for A. xylosoxidans lung infection in a lung-transplanted patient. The dynamics of airway colonization was more complex than deduced from bacterial culture, involving phage susceptible as well as phage resistant strains.

Comparative in vitro activities of meropenem in combination with colistin, levofloxacin, or chloramphenicol against Achromobacter xylosoxidans strains isolated from patients with cystic fibrosis.

OBJECTIVES: Achromobacter xylosoxidans is an emerging pathogen in cystic fibrosis (CF). Relatively little is known about its clinical impact and optimal management. In the present study, the in vitro bactericidal activities of meropenem, either alone or in combination with colistin, levofloxacin, or chloramphenicol, were assessed using A. xylosoxidans strains isolated from CF patients. The synergistic interactions of these combinations were also investigated. METHODS: Minimal inhibitory concentrations (MICs) were determined by microbroth dilution. Bactericidal and synergistic effects of the tested antibiotic combinations were assessed by using the time-kill curve technique. RESULTS: Based on the time-kill curves, we found that meropenem-colistin combinations have bactericidal and synergistic activities for 24 h against A. xylosoxidans strains, both at 1 × MIC and 4 × MIC. Although synergistic interactions were seen with meropenem-levofloxacin combinations, no bactericidal interactions were observed. Additionally, the meropenem-chloramphenicol combinations were found to be neither bactericidal nor synergistic. No antagonism was observed with any combination tested. CONCLUSIONS: This study's findings could have important implications for empirical or combination antimicrobial therapy with tested antibiotics.

Polymicrobial Intracerebral Abscess Growing Mycobacterium avium Complex and Achromobacter xylosoxidans: Case Report and Literature Review.

BACKGROUND: Mycobacterium avium complex (MAC) and Achromobacter xylosoxidans (AX) are uncommon sources of neurosurgical infections, particularly in immunocompetent hosts. We report the first published case of intracranial AX abscess and polymicrobial AX-MAC abscess, as well as the fourth MAC abscess in a non-immunocompromised patient. METHODS: This case report was conducted via retrospective chart review. A literature review was completed in compliance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. RESULTS: Ten years following mucocele resection, a 60-year-old man presented with sinus congestion and headache. Head imaging revealed a left frontal lesion abutting the cribriform plate and ethmoid roof. The patient had a left frontal craniotomy for abscess drainage. Intraoperative cultures demonstrated polymicrobial growth of AX and MAC, managed with antimicrobial therapy and staged skull base reconstruction. Three cases of MAC abscess and 16 cases of AX ventriculitis or meningitis have been reported in immunocompetent patients. All MAC cerebral abscesses occurred in adults, one of whom succumbed to the infection. Of the 9 AX meningitis cases, 4 occurred in neonates and 2 in pediatric patients. Six of the 7 AX ventriculitis cases occurred after neurosurgical operations at the same hospital from contaminated chlorhexidine basins. Except for the neonates, AX ventriculitis or meningitis patients had undergone neurosurgery or had a history of cranial trauma. There were no reports of polymicrobial AX-MAC intracranial abscess. CONCLUSIONS: AX and MAC are rare causes of intracranial infection. Patients with these pathogens identified in the central nervous system require a multidisciplinary approach for successful management.

AcGI1, a novel genomic island carrying antibiotic resistance integron In687 in multidrug resistant Achromobacter xylosoxidans in a teaching hospital in Thailand.

This study investigated the genetic basis of multidrug resistance in two strains of Achromobacter xylosoxidans isolated from patients attending a hospital in Thailand in 2012. These isolates were highly resistant to cephalosporins, aminoglycosides, fluoroquinolones, co-trimoxazole and carbapenems. Whole genome sequencing revealed that the two isolates were not clonally related and identified a carbapenem resistance gene-habouring integron (In687), residing in a novel genomic island, AcGI1. This In687 shares 100% identical nucleotide sequence with ones found in Acinetobacter baumannii Aci 16, isolated from the same hospital in 2007. We report the first analysis of multidrug-resistant A. xylosoxidans isolated in Thailand, and the first example of this island in A. xylosoxidans. Our data support the idea that resistance has spread in Thailand via horizontal gene transfer between species and suggest the possibility of A. xylosoxidans may serve as a reservoir of antibiotic resistance, especially in hospital setting.

Adhesion of Pseudomonas aeruginosa, Achromobacter xylosoxidans, Delftia acidovorans, Stenotrophomonas maltophilia to contact lenses under the influence of an artificial tear solution.

Corneal infection is a devastating sight-threatening complication that is associated with contact lens (CL) wear, commonly caused by Pseudomonas aeruginosa. Lately, Achromobacter xylosoxidans, Delftia acidovorans, and Stenotrophomonas maltophilia have been associated with corneal infection. This study investigated the adhesion of these emerging pathogens to CLs, under the influence of an artificial tear solution (ATS) containing a variety of components commonly found in human tears. Two different CL materials, etafilcon A and senofilcon A, either soaked in an ATS or phosphate buffered saline, were exposed to the bacteria. Bacterial adhesion was investigated using a radio-labeling technique (total counts) and plate count method (viable counts). The findings from this study revealed that in addition to P. aeruginosa, among the emerging pathogens evaluated, A. xylosoxidans showed an increased propensity for adherence to both CL materials and S. maltophilia showed lower viability. ATS influenced the viable counts more than the total counts on CLs.

A putative enoyl-CoA hydratase contributes to biofilm formation and the antibiotic tolerance of Achromobacter xylosoxidans.

Achromobacter xylosoxidans has attracted increasing attention as an emerging pathogen in patients with cystic fibrosis. Intrinsic resistance to several classes of antimicrobials and the ability to form robust biofilms in vivo contribute to the clinical manifestations of persistent A. xylosoxidans infection. Still, much of A. xylosoxidans biofilm formation remains uncharacterized due to the scarcity of existing genetic tools. Here we demonstrate a promising genetic system for use in A. xylosoxidans; generating a transposon mutant library which was then used to identify genes involved in biofilm development in vitro. We further described the effects of one of the genes found in the mutagenesis screen, encoding a putative enoyl-CoA hydratase, on biofilm structure and tolerance to antimicrobials. Through additional analysis, we find that a fatty acid signaling compound is essential to A. xylosoxidans biofilm ultrastructure and maintenance. This work describes methods for the genetic manipulation of A. xylosoxidans and demonstrated their use to improve our understanding of A. xylosoxidans pathophysiology.

Evaluation of the Immunochromatographic NG-Test Carba 5 for Rapid Identification of Carbapenemase in Nonfermenters.

The immunochromatographic assay NG-Test Carba 5 (NG-Biotech) was evaluated with a collection of 107 carbapenemase-producing nonfermenters (CP-NF) (55 Pseudomonas spp., 51 Acinetobacter spp., and 1 Achromobacter xylosoxidans isolate) and 61 carbapenemase-negative isolates. All KPC, VIM, and NDM carbapenemase producers tested were accurately detected. Of the 16 IMP variants tested, 6 (37.5%) variants were not detected. Considering the epidemiology of CP-NFs in France, the NG-Test Carba 5 would detect 89.4% of CP Pseudomonas spp. but only 12.9% of CP Acinetobacter spp.

Study of 109 Achromobacter spp. isolates from 9 French CF centres reveals the circulation of a multiresistant clone of A. xylosoxidans belonging to ST 137.

We previously reported the distribution of Achromobacter spp. (species and Sequence Types (ST)) in our French Cystic Fibrosis (CF) centre. In the present study we collected 109 Achromobacter isolates (1/patient) from 9 other French CF Centres for species identification, antimicrobial susceptibility testings and Multilocus-Sequence-Typing (MLST) analysis. Ten species were detected, A. xylosoxidans being the most predominant one (73.4% of the isolates). Piperacillin-tazobactam, ceftazidime, imipenem, meropenem and ciprofloxacin were respectively active against 88, 70, 79, 72 and 23% of the isolates. Among the 79 A. xylosoxidans isolates, 46 STs were detected. Interestingly, ST 137, recovered in 4 centres (5 patients), was previously detected in our centre (2 patients). The strains from the 7 patients belonged to the same pulsotype (pulsed-field-gel-electrophoresis analysis) and harboured acquired resistance to meropenem, ceftazidime, ciprofloxacin, and except for 2 isolates, to imipenem and piperacillin-tazobactam. This is the first description in France of a circulating multiresistant A. xylosoxidans strain.

Achromobacter xylosoxidans resistance to antiseptics and disinfectants is far from obvious.

BACKGROUND: Achromobacter xylosoxidans is described as being resistant to antiseptics and disinfectants. We studied in vitro the ability of five strains to survive and grow in such solutions, with and without starvation. METHODS: Bacterial suspensions in rich media and in distilled water were inoculated into eight antiseptics or disinfectants under conditions of use. RESULTS: All strains from cultures in distilled water survived in aqueous chlorhexidine and only environmental strains survived in a quaternary ammonium-based disinfectant. Survival did not exceed 30 min and no growth was observed. CONCLUSIONS: This study highlights a relationship between starvation and survival in antiseptics and disinfectants.

Fluoroquinolone-resistant Achromobacter xylosoxidans clinical isolates from Serbia: high prevalence of the aac-(6')-Ib-cr gene among resistant isolates.

The aim of this study was to evaluate the contribution of plasmid-mediated genes and efflux to fluoroquinolone resistance in collection of Achromobacter spp. gathered during a 3-year period. Susceptibility to ciprofloxacin and levofloxacin was tested by disk diffusion and microdilution tests for a collection of 98 Achromobacter spp. clinical isolates. Identification of fluoroquinolone-resistant isolates was performed by sequencing and phylogenetic analyses of the nrdA gene. Genetic relatedness among resistant isolates was determined by pulsed-field gel electrophoresis (PFGE) analysis. The influence of an H+ conductor cyanide m-chlorophenyl hydrazone (CCCP) and a resistance-nodulation-division-type efflux pump inhibitor phenylalanine-arginine beta-naphthylamide (PAßN) on minimal inhibitory concentration (MIC) value was evaluated by broth microdilution. The presence of the plasmid-mediated qnrA, qnrB, qnrC, qnrS, and aac-(6')-Ib-cr genes was investigated by PCR and sequencing. Achromobacter spp. isolates that were resistant or intermediately resistant to fluoroquinolones in disk diffusion tests (44/98) were subjected to microdilution. As a result, 20/98 isolates were confirmed to be resistant to ciprofloxacin while 10/98 was resistant to levofloxacin. CCCP decreased twofold MIC value for ciprofloxacin in six isolates and more than 16 times in one isolate, while MIC value for levofloxacin was decreased in all isolates (twofold to more than eightfold). Fluoroquinolone-resistant isolates were identified as A. xylosoxidans with the nrdA gene sequencing. PFGE revealed that resistant isolates belonged to seven different genotypes. Ten isolates belonging to four genotypes were positive for the aac-(6')-Ib-cr gene. Although resistance to fluoroquinolones was not widespread among analyzed isolates, detected contribution of efflux pumps and the presence of the aac-(6')-Ib-cr gene present a platform for emergence of more resistant strains.

In vitro activity of ß-lactams in combination with avibactam against multidrug-resistant Pseudomonas aeruginosa, Stenotrophomonas maltophilia and Achromobacter xylosoxidans isolates from patients with cystic fibrosis.

The in vitro activity of anti-pseudomonal ß-lactams in combination with avibactam was evaluated against 54 multidrug-resistant non-fermenting Gram-negative bacilli isolated from cystic fibrosis patients. Avibactam increased and/or restored the antibacterial activities of ceftazidime and aztreonam against Pseudomonas aeruginosa and Stenotrophomonas maltophilia, respectively. No ß-lactam-avibactam combination was active against Achromobacter xylosoxidans.

The successful treatment of a multidrug-resistant Achromobacter xylosoxidans corneal ulcer with topical meropenem.

Microbial keratitis is a common corneal condition, with many known risk factors. We present a case of an 88-year-old female patient with a multidrug-resistant Achromobacter xylosoxidans corneal ulcer in a previously failed second penetrating keratoplasty, successfully managed with topical meropenem drops administered hourly around the clock, for five days preceding and then hourly day only, for five days following a repeat third penetrating keratoplasty. Topical meropenem 50 mg/mL was prepared by mixing a 500 mg vial of meropenem with 10 mL of sterile water with pharmacy advice that administration should be within an hour. To the best of our knowledge, this is the first report of the use of topical meropenem in the management of A.xylosoxidans keratitis. This case highlights the importance of the mean inhibitory concentrations for antibiotics when considering sensitivities. Topical meropenem may be a useful treatment option for multidrug-resistant bacterial corneal ulcers that are resistant to conventional therapy.

Mediastinitis superinfected by Achromobacter xylosoxidans. A case report.

We describe an extremely rare case of mediastinitis superinfected by emerging Achromobacter xylosoxidans. After mitral and aortic valves replacement, the patient first developed a Staphylococcus aureus mediastinitis, and five days after starting adapted antibiotic therapy, superficial pus analysis revealed the presence of Achromobacter xylosoxidans. This superinfection was considered superficial and focus was made on Staphylococcus aureus mediastinitis. Three weeks later, no more Staphylococcus aureus was found in pus samples and the sepsis seemed under control. Unfortunately, blood cultures were again positive for Achromobacter xylosoxidans three weeks later and the patient died from septic shock.

Phage therapy against Achromobacter xylosoxidans lung infection in a patient with cystic fibrosis: a case report.

Respiratory infections can lead to serious complications in CF patients, especially when infected with antibiotic resistant bacteria. Alternative treatments for these infections are being sought out to help address this problem. We present a clinical case of a cystic fibrosis (CF) patient, with multi-drug resistant (MDR) Achromobacter xylosoxidans chronic lung infection who was successfully managed with bacteriophage therapy.

Achromobacter xylosoxidans bacteremia: clinical and microbiological features in a 10-year case series.

OBJECTIVE: The treatment of Achromobacter xylosoxidans bacteremia is challenged by antimicrobial resistance and the paucity of data. We aimed at offering a contemporary description of this uncommon entity. METHODS: Retrospective case series of 13 episodes of A. xylosoxidans bacteremia diagnosed over a 10-year period (November 2007 to May 2017) in our tertiary care center. RESULTS: Solid organ cancer and heart failure were the most common comorbidities (4/13 [30.7%]). All but one episodes were hospital-acquired. Most patients had received previous antibiotic therapy (7/13 [53.8%]) and had a central venous catheter in place (6/13 [46.1%]). Primary and intravascular catheter were the most common sources (4/13 [30.7%] each). Meropenem was the agent with best in vitro activity (92.3% [12/13] of susceptible isolates). All-cause 30-day mortality (overall 23.1%) was higher in patients with primary bacteremia (50.0% vs. 11.1%; P-value=0.203) and prior chemotherapy (66.7% vs. 10.0%; P-value=0.108). CONCLUSIONS: Bacteremia due to A. xylosoxidans constitutes a serious infection among immunocompromised hosts. Carbapenem-based therapy may be appropriate in most cases.

Proteomic identification of Axc, a novel beta-lactamase with carbapenemase activity in a meropenem-resistant clinical isolate of Achromobacter xylosoxidans.

The development of antibiotic resistance during treatment is a threat to patients and their environment. Insight in the mechanisms of resistance development is important for appropriate therapy and infection control. Here, we describe how through the application of mass spectrometry-based proteomics, a novel beta-lactamase Axc was identified as an indicator of acquired carbapenem resistance in a clinical isolate of Achromobacter xylosoxidans. Comparative proteomic analysis of consecutively collected susceptible and resistant isolates from the same patient revealed that high Axc protein levels were only observed in the resistant isolate. Heterologous expression of Axc in Escherichia coli significantly increased the resistance towards carbapenems. Importantly, direct Axc mediated hydrolysis of imipenem was demonstrated using pH shift assays and 1H-NMR, confirming Axc as a legitimate carbapenemase. Whole genome sequencing revealed that the susceptible and resistant isolates were remarkably similar. Together these findings provide a molecular context for the fast development of meropenem resistance in A. xylosoxidans during treatment and demonstrate the use of mass spectrometric techniques in identifying novel resistance determinants.

In vitro antimicrobial activity of ceftolozane/tazobactam against Pseudomonas aeruginosa and other non-fermenting Gram-negative bacteria in adults with cystic fibrosis.

OBJECTIVES: Pulmonary exacerbations in patients with cystic fibrosis (CF) caused by chronic Gram-negative bacterial infections are associated with reduced survival. These pathogens are usually treated with repeated courses of systemic antimicrobial agents. However, there is associated emergence of multidrug-resistant (MDR) pathogens. Ceftolozane/tazobactam (C/T) is a novel cephalosporin/ß-lactamase inhibitor combination that has been demonstrated to have good activity against MDR Pseudomonas aeruginosa. METHODS: In this study, C/T was compared with other commonly used intravenous antimicrobial agents against 193 non-fermenting Gram-negative bacteria isolated from CF sputum specimens, including P. aeruginosa, Achromobacter xylosoxidans, Stenotrophomonas maltophilia and Burkholderia cenocepacia. Minimum inhibitory concentrations (MICs) to C/T were determined by standard Etest assay and were interpreted according to current European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. RESULTS: C/T had good in vitro antimicrobial activity against CF clinical isolates of P. aeruginosa in comparison with other antimicrobial agents, with the exception of colistin. C/T also had activity against S. maltophilia but was not active against B. cenocepacia or A. xylosoxidans. CONCLUSION: C/T showed excellent in vitro activity against P. aeruginosa CF clinical isolates. This antimicrobial agent is a potential therapeutic option when presented with challenging MDR P. aeruginosa and S. maltophilia exacerbations. Further clinical experience and trials in CF are required to determine the place of C/T in clinical practice.

Comparative activity of antimicrobials against Pseudomonas aeruginosa, Achromobacter xylosoxidans and Stenotrophomonas maltophilia keratitis isolates.

BACKGROUND/AIMS: Achromobacter xylosoxidans and Stenotrophomonas maltophilia are emerging corneal pathogens, which are closely related to Pseudomonas aeruginosa, and have intrinsic resistance to many commonly available antimicrobials. The purpose of this study is to compare the in vitro efficacy of 12 antimicrobial agents against A. xylosoxidans, S. maltophilia and P. aeruginosa isolates recovered from clinical cases of keratitis. METHODS: Recovered corneal isolates (n=58) were identified and extracted from the Microbiology Data Bank of the Bascom Palmer Eye Institute. Comparative in vitro minimum inhibitory concentration (MIC) susceptibility profiles for fluoroquinolones, aminoglycosides, beta-lactams and miscellaneous antibiotics were recorded using the E-test methodology. Pharmacodynamic indices (Cmax/MIC) were calculated. RESULTS: A. xylosoxidans and S. maltophilia isolates were resistant to fluoroquinolones, aminoglycosides and ceftazidime (susceptibility rate ranging from 0% to 30%) while P. aeruginosa isolates showed a susceptibility rate of 95%-100% to these antimicrobials (P<0.00001 for the various antimicrobials). Exception was moxifloxacin with 80% of susceptibility rate to S. maltophilia isolates and Cmax/MIC=10.19. Ninety to 100% susceptibility rates were found for minocycline and trimethoprim/sulfamethoxazole for both A. xylosoxidans and S. maltophilia. One hundred per cent of the A. xylosoxidans isolates were susceptible to piperacillin/tazobactam and ticarcillin/clavulanic acid. CONCLUSIONS: There is a significant difference in susceptibility patterns between A. xylosoxidans, S. maltophilia and P. aeruginosa. Fluoroquinolones and aminoglycosides may not be effective against A. xylosoxidans and S. maltophilia. Antibiotics that are not commercially available as eye drops, such as beta-lactams for A. xylosoxidans, and trimethoprim/sulfamethoxazole and minocycline for both A. xylosoxidans and S. maltophilia should be considered.

The Antibacterial and Anti-inflammatory Activity of Chicken Cathelicidin-2 combined with Exogenous Surfactant for the Treatment of Cystic Fibrosis-Associated Pathogens.

Cystic fibrosis (CF) is characterized by recurrent airway infections with antibiotic-resistant bacteria and chronic inflammation. Chicken cathelicin-2 (CATH-2) has been shown to exhibit antimicrobial activity against antibiotic-resistant bacteria and to reduce inflammation. In addition, exogenous pulmonary surfactant has been suggested to enhance pulmonary drug delivery. It was hypothesized that CATH-2 when combined with an exogenous surfactant delivery vehicle, bovine lipid extract surfactant (BLES), would exhibit antimicrobial activity against CF-derived bacteria and downregulate inflammation. Twelve strains of CF-pathogens were exposed to BLES+CATH-2 in vitro and killing curves were obtained to determine bactericidal activity. Secondly, heat-killed bacteria were administered in vivo to elicit a pro-inflammatory response with either a co-administration or delayed administration of BLES+CATH-2 to assess the antimicrobial-independent, anti-inflammatory properties of BLES+CATH-2. CATH-2 alone exhibited potent antimicrobial activity against all clinical strains of antibiotic-resistant bacteria, while BLES+CATH-2 demonstrated a reduction, but significant antimicrobial activity against bacterial isolates. Furthermore, BLES+CATH-2 reduced inflammation in vivo when either co-administered with killed bacteria or after delayed administration. The use of a host-defense peptide combined with an exogenous surfactant compound, BLES+CATH-2, is shown to exhibit antimicrobial activity against antibiotic-resistant CF bacterial isolates and reduce inflammation.