Molecular characterizations of carbapenem and ciprofloxacin resistance in clinical isolates of Pseudomonas putida

Do mould inhibitors alter the microbial community structure and antibiotic resistance gene profiles on textiles?

Mould inhibitors are closely associated with human health and have been extensively applied to textiles to prevent mould and insect infestations. However, the impact of these mould inhibitors on the microbial community structure on textiles and antibiotic resistance gene (ARG) profiles remains largely unexplored. In this study, testing techniques, including high-throughput quantitative PCR and Illumina sequencing, were employed to analyse the effects of three types of mould inhibitors -para-dichlorobenzene (PDCB), naphthalene, and natural camphor balls-on the composition of microbial communities and ARG profiles. The microbial mechanisms underlying these effects were also investigated. The experiments revealed that PDCB reduced the diversity of bacterial communities on textiles, whereas naphthalene and natural camphor balls exerted relatively minor effects. In contrast with bacterial diversity, PDCB enhanced the diversity of fungal communities on textiles, but significantly reduced their abundance. Naphthalene had the least impact on fungal communities; however, it notably increased the relative abundance of Basidiomycota. All three types of mould inhibitors substantially altered ARG profiles. Potential mechanisms responsible for the alterations in ARG profiles include microbial community succession and horizontal gene transfer mediated by mobile genetic elements. PDCB prominently increased the abundance of ARGs, mainly attributable to the relative enrichment of potential hosts (including certain γ-Proteobacteria and Bacillales) for specific ARGs. Thus, this study has important implications for the selection of mould inhibitors, as well as the assessment of microbial safety in textiles.

Cross-Over Pathogenic Bacteria Detected in Infected Tomatoes (Solanum lycopersicum L.) and Peppers (Capsicum annuum L.) in Bulgaria

The ability of certain human pathogens to adapt to plants without losing their virulence toward people is a major concern today. Thus, the aim of the present work was the investigation of the presence of cross-over pathogenic bacteria in infected tomato and pepper plants. The objects of the study were 21 samples from seven different parts of the plants and three from tomato rhizosphere. In total, 26 strains were isolated, identified by MALDI-TOF, and phenotypically characterized. The PCR amplification of the rpoB gene was applied as an approach for the rapid detection of cross-over pathogens in plant samples. A great bacterial diversity was revealed from tomato samples as nine species were identified (Leclercia adecarboxylata, Pseudesherichia vulneris, Enterobacter cancerogenus, Enterobacter cloacae, Enterobacter bugandensis, Acinetobacter calcoaceticus, Pantoea agglomerans, Pantoea ananatis, and Pectobacterium carotovorum). Polymicrobial contaminations were observed in samples T2 (tomato flower) and T10 (tomato fruit). Five species were identified from pepper samples (P. agglomerans, L. adecarboxylata, Pseudomonas sp., Pseudomonas putida, and Enterococcus sp.). Antibiotic resistance patterns were assigned in accordance with EFSA recommendations. All isolates showed varying resistance to the tested antibiotics. The genetic basis for the phenotypic antibiotic resistance was not revealed. No genes for the virulence factors were found among the population. To our knowledge, this is the first overall investigation of tomato and pepper cross-over pathogenic bacterial populations in Bulgaria.

Enhancing the 1-Aminocyclopropane-1-Carboxylate Metabolic Rate of Pseudomonas sp. UW4 Intensifies Chemotactic Rhizocompetence

1-aminocyclopropane-1-carboxylic acid (ACC) is a strong metabolism-dependent chemoattractant for the plant beneficial rhizobacterium Pseudomonas sp. UW4. It is unknown whether enhancing the metabolic rate of ACC can intensify the chemotaxis activity towards ACC and rhizocompetence. In this study, we selected four promoters to transcribe the UW4 ACC deaminase (AcdS) gene in the UW4 ΔAcdS mutant. PA is the UW4 AcdS gene promoter, PB20, PB10 and PB1 are synthetic promoters. The order of the AcdS gene expression level and AcdS activity of the four strains harboring the promoters were PB20 > PA > PB10 > PB1. Interestingly, the AcdS activity of the four strains and their parent strain UW4 was significantly positively correlated with their chemotactic activity towards ACC, rhizosphere colonization, roots elongation and dry weight promotion. The results released that enhancing the AcdS activity of PGPRenable them to achieve strong chemotactic responses to ACC, rhizocompetence and plant growth promotion.

Emergence of Carbapenem-Resistant Pseudomonas asiatica Producing NDM-1 and VIM-2 Metallo-β-Lactamases in Myanmar

Pseudomonas asiatica is a recently proposed species of the genus Pseudomonas This study describes eight isolates of carbapenem-resistant P. asiatica harboring bla _NDM-1 and bla _VIM-2, genes encoding metallo-β-lactamase (MBL). These isolates were obtained from urine samples of patients hospitalized in Myanmar. These isolates were resistant to carbapenems but susceptible to colistin. All eight isolates were positive for a carbapenemase inactivation method, CIMTrisII, and seven were positive on an immunochromatographic assay for NDM-type MBL. One isolate was highly resistant to aminoglycosides. Whole-genome sequencing showed that seven isolates harbored bla _NDM-1 and one harbored bla _VIM-2, with these genes located on the chromosome. One isolate harbored bla _NDM-1 and rmtC, a gene encoding 16S rRNA methylase. Five types of genomic environments surrounding bla _NDM-1 and bla _VIM-2 were detected in these eight isolates, with four isolates having the same type. These data indicate that P. asiatica isolates harboring genes encoding carbapenemases, including bla _NDM-1 and bla _VIM-2, are spreading in medical settings in Myanmar.

Characterization of antimicrobial resistance mechanisms in carbapenem-resistant Pseudomonas aeruginosa carrying IMP variants recovered from a Mexican Hospital

Purpose

Pseudomonas aeruginosa infections in hospitals constitute an important problem due to the increasing multidrug resistance (MDR) and carbapenems resistance. The knowledge of resistance mechanisms in Pseudomonas strains is an important issue for an adequate antimicrobial treatment. Therefore, the objective was to investigate other antimicrobial resistance mechanisms in MDR P. aeruginosa strains carrying bla_IMP, make a partial plasmids characterization, and determine if modifications in oprD gene affect the expression of the OprD protein.

Methodology

Susceptibility testing was performed by Kirby Baüer and by Minimum Inhibitory Concentration (presence/absence of efflux pump inhibitor); molecular typing by Pulsed-field gel electrophoresis (PFGE), resistance genotyping and integrons by PCR and sequencing; OprD expression by Western blot; plasmid characterization by MOB Typing Technique, molecular size by PFGE-S1; and bla_IMP location by Southern blot.

Results

Among the 59 studied P. aeruginosa isolates, 41 multidrug resistance and carbapenems resistance isolates were detected and classified in 38 different PFGE patterns. Thirteen strains carried bla_IMP; 16 bla_GES and four carried both genes. This study centered on the 17 strains har-boring bla_IMP. New variants of β-lactamases were identified (bla_GES-32, bla_IMP-56, bla_IMP-62) inside of new arrangements of class 1 integrons. The presence of bla_IMP gene was detected in two plasmids in the same strain. The participation of the OprD protein and efflux pumps in the resistance to carbapenems and quinolones is shown. No expression of the porin OprD due to stop codon or IS in the gene was found.

Conclusions

This study shows the participation of different resistance mechanisms, which are reflected in the levels of MIC to carbapenems. This is the first report of the presence of three new variants of β-lactamases inside of new arrangements of class 1 integrons, as well as the presence of two plasmids carrying bla_IMP in the same P. aeruginosa strain isolated in a Mexican hospital.

Indole-Induced Activities of β-Lactamase and Efflux Pump Confer Ampicillin Resistance in Pseudomonas putida KT2440

Indole, which is widespread in microbial communities, has received attention because of its effects on bacterial physiology. Pseudomonas putida and Pseudomonas aeruginosa can acquire ampicillin (Amp) resistance during growth on indole-Amp agar. Transcriptome, mutant, and inhibitor studies have suggested that Amp resistance induced by indole can be attributed to increased gene expression of ttgAB encoding two genes of RND-type multidrug efflux operons and an ampC encoding β-lactamase. Expression, enzyme activities, and mutational analyses indicated that AmpC β-lactamase is important for acquiring Amp resistance of P. putida in the presence of indole. Here, we show, for the first time, that volatile indole increased Amp-resistant cells. Consistent with results of the volatile indole assay, a low concentration of indole in liquid culture promoted growth initially, but led to mutagenesis after indole was depleted, which could not be observed at high indole concentrations. Interestingly, ttgAB and ampC gene expression levels correlate with the concentration of indole, which might explain the low number of Amp-mutated cells in high indole concentrations. The expression levels of genes involved in mutagenesis, namely rpoS, recA, and mutS, were also modulated by indole. Our data indicates that indole reduces Amp-induced heterogeneity by promoting expression of TtgABC or MexAB-OprM efflux pumps and the indole-induced β-lactamase in P. putida and P. aeruginosa.

Isolation of carbapenem-resistant Pseudomonas spp. from food

Pseudomonas spp. are ubiquitous in nature. Carbapenem resistance in environmental isolates of members of this genus is thought to be rare but the exact resistance rate is unknown. In this study, carbapenem-resistant Pseudomonas spp. were isolated from chicken and pork samples and the mechanisms underlying the carbapenem resistance in these strains were investigated. A total of 16 carbapenem-resistant Pseudomonas aeruginosa, Pseudomonas putida and Pseudomonas otitidis isolates were recovered from eight samples of chicken and pork. The isolates exhibited meropenem minimum inhibitory concentrations (MICs) of 8 to ≥32mg/L and imipenem MICs of <0.5-16mg/L yet did not harbour any acquired carbapenemase genes. Meropenem resistance in various strains was found to be mediated by efflux systems only, whereas overexpression of MexAB-OprM efflux pump and lack of OprD porin were responsible for carbapenem resistance in P. aeruginosa. The intrinsic metallo-β-lactamase gene bla_POM in P. otitidis and overexpression of the TtgABC efflux system in P. putida were also responsible for carbapenem resistance in these organisms. In conclusion, this study reports for the first time the isolation of carbapenem-resistant P. aeruginosa, P. otitidis and P. putida strains from food. The resistance mechanisms of these strains are rarely due to production of carbapenemases. Further selection of such carbapenem-resistant Pseudomonas spp. in the environment and the risk by which they are transmitted to clinical settings are of great public health concern.

Diabetic Foot Gangrene Patient with Multi-drug Resistant Pseudomonas Putida Infection in Karawaci District, Indonesia

Pseudomonas putida is a rod-shaped, non fermenting Gram-negative organism frequently found in the environment that utilizes aerobic metabolism, previously thought to be of low pathogenicity. It had been reported as cause of skin and soft tissue infection, especially in immunocompromised patients. A female green grocer, 51 year-old came to internal medicine out-patient clinic with gangrene and osteomyelitis on her 1^st, 2^nd and 3^rd digit and wound on the sole of the right foot since 1 month prior. The patient had history of uncontrolled diabetes since a year ago. She was given ceftriaxone 2 grams b.i.d, metronidazole 500 mg t.i.d empirically and then amikacin 250 mg b.i.d, followed by amputation of the digits and wound debridement. The microorganism's culture from pus revealed multi drug resistant Pseudomonas putida. She recovered well after antibiotics and surgery.

Antibiotic resistance determinants in a Pseudomonas putida strain isolated from a hospital

Environmental microbes harbor an enormous pool of antibiotic and biocide resistance genes that can impact the resistance profiles of animal and human pathogens via horizontal gene transfer. Pseudomonas putida strains are ubiquitous in soil and water but have been seldom isolated from humans. We have established a collection of P. putida strains isolated from in-patients in different hospitals in France. One of the isolated strains (HB3267) kills insects and is resistant to the majority of the antibiotics used in laboratories and hospitals, including aminoglycosides, ß-lactams, cationic peptides, chromoprotein enediyne antibiotics, dihydrofolate reductase inhibitors, fluoroquinolones and quinolones, glycopeptide antibiotics, macrolides, polyketides and sulfonamides. Similar to other P. putida clinical isolates the strain was sensitive to amikacin. To shed light on the broad pattern of antibiotic resistance, which is rarely found in clinical isolates of this species, the genome of this strain was sequenced and analysed. The study revealed that the determinants of multiple resistance are both chromosomally-borne as well as located on the pPC9 plasmid. Further analysis indicated that pPC9 has recruited antibiotic and biocide resistance genes from environmental microorganisms as well as from opportunistic and true human pathogens. The pPC9 plasmid is not self-transmissible, but can be mobilized by other bacterial plasmids making it capable of spreading antibiotic resistant determinants to new hosts.

Nosocomial Pseudomonas putida Bacteremia: High Rates of Carbapenem Resistance and Mortality

Previously, Pseudomonas putida was considered a low-virulence pathogen and was recognized as a rare cause of bacteremia. Recently, however, multidrug-resistant and carbapenem-resistant P. putida isolates have emerged, causing difficult-to-treat nosocomial infections in seriously ill patients. Currently, the outcome of multidrug-resistant or carbapenem-resistant P. putida bacteremia remains uncertain. Here, we report 18 cases of P. putida bacteremia with high rates of carbapenem resistance and mortality. From January 2005 through December 2011, all cases of nosocomial P. putida bacteremia were identified and analyzed at Chonnam National University Hospital and Chonnam National University Hwasun Hospital. Electronic medical records were reviewed retrospectively. Four (22%) and five (23%) of 18 P. putida isolates were resistant to imipenem and meropenem, respectively. Common primary infection sites were central venous catheter (7, 39%), pneumonia (5, 28%), and cholangitis (2, 11%). Fourteen (78%) patients had indwelling devices related to the primary site of infection. The 30-day mortality rate was 39% (7/18): 40% (2/5) in patients with carbapenem-resistant P. putida bacteremia vs. 38% (5/13) in patients with carbapenem-susceptible P. putida bacteremia. Nosocomial P. putida bacteremia showed high resistance rates to most potent β-lactams and carbapenems and was associated with high mortality rates.