Severe Nosocomial Infections Research Articles

Особенности антибиотикорезистентности по данным микробиологического мониторинга в многопрофильном стационаре

Microbiological monitoring allows epidemiologists and clinical pharmacologists to control hospital-acquired infections and make timely strategic decisions. The purpose — to determine the tendency of prevailing problem microflora and to develop a strategy of empirical antibacterial therapy for severe nosocomial infections and inflammatory processes. Material and methods. The article analyzes the main groups of pathogens of hospital infections in dynamics for the first quarter of 2018, 2019 and 2020. The relation of positive cultures to the total number of investigated samples was taken for the analysis. Antibiotic sensitivity was isolated, identified and determined using conventional mass spectrometry methods. The results. The stable sowing rate of Acinetobacter baumannii and Klebsiella pneumoniae in the intensive care and surgical departments was noted for the analyzed periods. To solve the problem of antibiotic resistance in the inpatient department, a strategy to contain it was developed.

9. Evaluation of Synergy Testing Methods for Clinical Labs to Determine Susceptibility of Extensively Drug-resistant Gram-negatives to Ceftazidime/ Avibactam and Aztreonam Combination Therapy

BackgroundCarbapenem-resistant Enterobacterales (CRE) and Pseudomonas aeruginosa (CR-PA) producing Metallo-β-lactamases (MBLs) cause severe nosocomial infections with no defined treatment. Combination therapy with ceftazidime/ avibactam (CZA) and aztreonam (ATM) is a potential option, but there is no approved, feasible, synergy testing method for clinical labs to guide clinical decision making. Here, we evaluate the performance of 4 synergy testing methods using gradient-strips or disks.MethodsWe used 10 representative Enterobacterales strains, namely, E. coli, K. pneumoniae, and E. cloacea, and 6 PA strains harboring MBL, GES or non-MBL enzymes (Fig 1). 4 strains were successfully treated with CZA-ATM in case reports, the rest were from the CDC AR Bank. Four synergy testing methods were evaluated, i) Disk stack (DS), ii) Disk elution (DE), iii) Gradient-strip Stack (SS), iv) Gradient-strip Cross (SX) (Fig 1). All methods were run side-by-side as per CLSI guidelines with broth microdilution (BMD) as the reference. Data is the mean of 3 replicates. Synergy is defined as a strain that is resistant (R) to ATM but drops to ≤ the susceptible (S) breakpoint (Table 1) in the presence of CZA (Fig 2). Categorical agreement (CA), very major error (VME), major error (ME), minor error (MI) were calculated across methods for CZA-ATM synergy relative to BMD.Summary of synergy testing methods evaluated CLSI Breakpoints used for this study ResultsAll CRE with NDM and PA with GES were ATM-R, CZA-R and S to the CZA-ATM combination. PA with NDM or VIM remained R to CZA-ATM likely due to other mechanisms of resistance. CA was high for DE (100%), SS (81%, MI 19%), and SX (88%, MI 13%) but low for DS (25%, ME 54%, MI 31%). Representative strains are shown (Fig 2, Table 2). Removing PA, CA for DE, SS, and SX was 100% and 20% for DS.Representative results of strains with each synergy testing method. Representative data of strains displaying synergy (green) or no synergy (red)ConclusionOverall, DE was the most reliable method for CZA-ATM synergy testing, and could be a valuable tool in low-resource labs. SS and SX were reliable but prone to technical error. DS had the worst performance. Disks and gradient-strips had identical performance across brands. We propose an algorithm for ATM-R, CZA-R, and MBL-positive CRE, where CZA-ATM synergy testing may be beneficial to guide therapy. These methods are reliable qualitative indicators of the presence or absence of synergy. Synergy testing is not recommended for CR-PA due to complex resistance profiles. Disclosures Cesar A. Arias, M.D., MSc, Ph.D., FIDSA, Entasis Therapeutics (Scientific Research Study Investigator)MeMed (Scientific Research Study Investigator)Merck (Grant/Research Support) William R. Miller, MD, Entasis Therapeutics (Scientific Research Study Investigator)Merck (Grant/Research Support)Shionogi (Advisor or Review Panel member)

Broadly reactive human CD4+ T cells against Enterobacteriaceae are found in the naïve repertoire and are clonally expanded in the memory repertoire.

Enterobacteriaceae are a large family of Gram‐negative bacteria that includes both commensals and opportunistic pathogens. The latter can cause severe nosocomial infections, with outbreaks of multi‐antibiotics resistant strains, thus being a major public health threat. In this study, we report that Enterobacteriaceae‐reactive memory Th cells were highly enriched in a CCR6+CXCR3+ Th1*/17 cell subset and produced IFN‐γ, IL‐17A, and IL‐22. This T cell subset was severely reduced in septic patients with K. pneumoniae bloodstream infection who also selectively lacked circulating K. pneumonie‐reactive T cells. By combining heterologous antigenic stimulation, single cell cloning and TCR Vβ sequencing, we demonstrate that a large fraction of memory Th cell clones was broadly cross‐reactive to several Enterobacteriaceae species. These cross‐reactive Th cell clones were expanded in vivo and a large fraction of them recognized the conserved outer membrane protein A antigen. Interestingly, Enterobacteriaceae broadly cross‐reactive T cells were also prominent among in vitro primed naïve T cells. Collectively, these data point to the existence of immunodominant T cell epitopes shared among different Enterobacteriaceae species and targeted by cross‐reactive T cells that are readily found in the pre‐immune repertoire and are clonally expanded in the memory repertoire.

Incidence of multidrug-resistant bacteria in tracheal secretions from critically ill patients in the intensive care unit

Abstract Ventilator-associated pneumonia is a severe nosocomial infection that affects the disease course of critically ill patients. Awareness of potential pathogens is essential for prevention, early detection, and proper treatment, as well. In this retrospective cross-sectional study, we investigated the tracheal secretions collected from critically ill patients with the aim to detect the occurrence of multidrug-resistant bacteria. We examined the bacteriological culture results of the tracheal secretions of the patients hospitalized at the Intensive Care Unit of Tîrgu Mureș Emergency Clinical County Hospital between 1st November 2017 and 31st January 2018. Admission diagnoses and comorbidities were recorded, and white blood cell counts were monitored. We determined the quality of the lower respiratory samples by microscopic examination and the results of the microbiological tests, taking into account the germ count of pathogens and the antibiotic-resistance pheno-type. During the three months, 194 samples were received from 107 patients for bacteriological examination. After the first sample collection 34 (31.77%) tracheal secretions were positive for pathogens, while in the remaining samples normal upper respiratory bacterial flora was found. From the 34 positive samples, 22 were colonizing pathogens and 30 were isolated in a clinically significant amount. Predominantly Staphylococcus aureus (n=14; 26.9%), Klebsiella pneumoniae (n=9; 17.3%), Escherichia coli (n=8.1%) and other Gram-negative bacteria (n=21; 40.4%) were identified. Among these strains 38 (73.07%) were not multidrug-resistant. The rate of positivity of individual sampling showed a positive correlation with the average duration of hospital stay (p=0.0016; r=0.8740). A total of 26 patients developed early-onset or late-onset ventilator-associated pneumonia. Potential risk factors for infection with multidrug-resistant bacteria were found. We can conclude that recently admitted patients in the intensive care unit are rarely carriers of multidrug-resistant bacteria, but become colonized or infected with multidrug-resistant strains during long-term intensive care.

Plant Derived Natural Products against Pseudomonas aeruginosa and Staphylococcus aureus: Antibiofilm Activity and Molecular Mechanisms.

Bacteria are social organisms able to build complex structures, such as biofilms, that are highly organized surface-associated communities of microorganisms, encased within a self- produced extracellular matrix. Biofilm is commonly associated with many health problems since its formation increases resistance to antibiotics and antimicrobial agents, as in the case of Pseudomonas aeruginosa and Staphylococcus aureus, two human pathogens causing major concern. P. aeruginosa is responsible for severe nosocomial infections, the most frequent of which is ventilator-associated pneumonia, while S. aureus causes several problems, like skin infections, septic arthritis, and endocarditis, to name just a few. Literature data suggest that natural products from plants, bacteria, fungi, and marine organisms have proven to be effective as anti-biofilm agents, inhibiting the formation of the polymer matrix, suppressing cell adhesion and attachment, and decreasing the virulence factors’ production, thereby blocking the quorum sensing network. Here, we focus on plant derived chemicals, and provide an updated literature review on the anti-biofilm properties of terpenes, flavonoids, alkaloids, and phenolic compounds. Moreover, whenever information is available, we also report the mechanisms of action.

Clonal relatedness in the acquisition of intestinal carriage and transmission of multidrug resistant (MDR) Klebsiella pneumoniae and Escherichia coli and its risk factors among preterm infants admitted to the neonatal intensive care unit (NICU)

Gastrointestinal carriage of multidrug resistant (MDR) Gram-negative bacilli, especially Klebsiella pneumoniae and Escherichia coli, was highly associated with severe nosocomial infections. The main objectives of this study were to determine the clonal relatedness of intestinal carriage and transmission risk factors of MDR E. coli and K. pneumoniae amongst preterm infants admitted to the neonatal intensive care unit (NICU). A prospective cohort study of preterm infants with gestational age<37 weeks was conducted in the NICU of the University of Malaya Medical Centre (UMMC). Infants' stool specimens were collected on day 1 (meconium), week 1, week 2, week 8 and week 10 during their admission (from 1st June to 31st August 2017) until discharge. The presence and antibiotic resistance pattern of MDR E. coli and K. pneumoniae were determined. Strain clonality and relatedness were explored via pulsed-field gel electrophoresis (PFGE) fingerprints. The risk factors for MDR strains acquisition were evaluated using the Cox proportional-hazards model and Firth logistic regression. A total of 139 stool specimens were obtained from 50 subjects. Twenty-six (52%) infants were colonized with MDR K. pneumoniae and/or E. coli. High clonal dissemination between two clusters of ESBL-producing K. pneumoniae strains was seen from PFGE profile. We detected a persistent, dominant, aminoglycosides-resistant strains cluster (cluster B), which harbored blaTEM, blaSHV, blaOXA-1, blaCTX-M-1, ompK35 and ompK36 genes. Infants born to women who were anemic in pregnancy [OR=0.01 (CI=0.00-0.39), P-value=0.042] and infants exposed to penicillin/β-lactams group antibiotics during the first week of life [OR=0.02 (CI=0.02-0.32), P-value=0.013] were found to have a lower risk of MDR K. pneumoniae and E. coli colonization. The prevalence of dominant aminoglycosides-resistant strains cluster in the NICU is alarming. Awareness of and vigilance for the dominant cluster found will enable the reduction of cross-transmission amongst high-risk infants.

Evaluating the frequency of carbapenem and aminoglycoside resistance genes among clinical isolates of Acinetobacter baumannii from Ahvaz, south-west Iran.

Acinetobacter baumannii is one of the most important opportunistic challenging pathogens as a result of its ability to acquire resistance to broad range of antibiotics and cause a variety of severe nosocomial infections. We investigated the frequency of the aminoglycoside-modifying enzymes (AMEs) and oxacillinase genes among clinical isolates of A. baumannii collected from hospitalized patients in Imam Khomeini Hospital, Ahvaz city, Iran. This prospective cross-sectional study was performed on 80 clinical isolates of A. baumannii collected from patients referred to Imam Khomeini Hospital in Ahvaz, Iran. Initial identification of isolates as A. baumannii was performed using conventional bacteriologic tests, and final confirmation was carried out by PCR of blaOXA-51-like gene and multiplex PCR of gyrB locus. MICs of different classes of antibiotics against these strains was measured by using VITEK 2 system. After extraction of genomic DNA, two groups of multidrug-resistant A. baumannii genes including AME (aadA1, aadB, aphA6 and aacC1) and oxacillinases (blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, blaOXA-58-like and blaOXA-143-like) were detected. According to antibiotic susceptibility testing, among 80 A. baumannii strains, 75 isolates (91.25%) were multidrug resistant. The results showed that colistin and tigecycline, with respective sensitivity rates of 97.5% (78/80) and 56.25% (45/80), had the highest effects. The presence of blaOXA-51-like and gyrB genes was confirmed in all strains. Furthermore, blaOXA-23-like and blaOXA-24-like genes were found in 68.75% (55/80) and 20% (16/80) of isolates respectively, while no isolate harbored the blaOXA-143-like gene. The frequency of genes encoding the AMEs including aadA1, aacC1, aphA6 and aadB were 11.25% (9/80), 16.25% (13/80), 22.5% (18/80) and 30% (24/80) respectively. Our findings indicate that the presence of the aadB and aphA6 is correlated with high resistance against amikacin and gentamicin. We found a very high resistance rate against most of the antimicrobial agents usually prescribed for severe infections caused by A. baumannii. Therefore, because of rapid emergence of resistance even for colistin or tigecycline, monotherapy should be avoided. These results show the importance of providing antibiotics correctly in intensive care units and following antibiotic stewardship protocols as the only effective strategies to attempt to control antibiotic resistance in healthcare settings.

Antifungal Efficacy of Chitosan-Stabilized Biogenic Silver Nanoparticles against Pathogenic Candida spp. Isolated from Human

Biogenic silver nanoparticles (Bio-AgNPs) have been recognized to play a major role in the fight against multi-drug-resistant pathogens. The present study evaluates antifungal efficacy of biogenic AgNPs conjugated with a natural polymer chitosan (derived from shrimp (Penaeus monodon) shells). Bio-AgNPs used for conjugation were produced by a mycoendophyte Colletotrichum gloeosporioides (KX881911) isolated from the medicinal plant Withania somnifera (L.). During the last decade, although numerous reports on Bio-AgNPs with antimicrobial activity have been reported, insights on the usage of conjugates of Bio-AgNPs have been scarce. Candida species are responsible for severe nosocomial infections and which has developed resistance against many antifungal agents. The current study aims to evaluate the antifungal activity of Bio-AgNPs conjugated with chitosan (Ch Bio-AgNPs) on various Candida species isolated from patients. The fungicidal activity was screened by well diffusion assay and TTC assay. Antibiofilm activity against Candida species was well elucidated by Congo red agar and Crystal Violet assay. Ch Bio-AgNPs showed the potent antifungal effect at 50 μg/ml concentration on all the selected Candida species, and the disruption and distortion of cells were documented well with transmission electron microscopy (TEM). The TEM images showed adhesion and entry of Ch Bio-AgNPs into the cells and release of cellular inclusions along with cell damage and distorted cell morphology. To conclude, the study suggests that Ch Bio-AgNP is a potential antifungal agent to treat drug-resistant pathogenic Candida species.

The Role of Bacterial Biofilms in Infections and Effective Prevention Strategies for Biofilm Formation in Urinary Catheters

Biofilm formation is a complicated microbiological process and one of the distinctive features of pathogenic bacteria. Biofilms are a cluster of bacterial cells enclosed in extra polymeric substances and irreversibly attached onto a surface. Biofilms have a major impact on public health as biofilm associated bacteria are able to survive and populate in indwelling medical devices, causing severe nosocomial and recurrent infections. Biofilm-embedded bacteria have unique characteristics which are harder to destroy than the planktonic forms. Especially biofilm bacteria are highly resistant to antimicrobial agents. Treating patients undergoing long term urinary catheterization is becoming complicated by encrustation and blockage due to crystalline biofilm formation inside the lumen of catheters. Further, all types of indwelling catheters including silver or nitrofurazone‐coated devices are vulnerable to biofilm formation. Therefore, there is an urgent requirement to develop either urinary catheters with other alternative coatings or new urinary drainage systems which may lead to reduction of infections and morbidity. Other than that, controlling biofilm formation is a necessary requirement during both manufacturing and usage of catheters. Antifouling and biocidal coatings on the catheters are currently being investigated and it is proved that herbal products also express anti-biofilm activity. This review is largely based on previous literature describing biofilm formation and their role in catheter associated urinary tract infection. Further, mechanism of biofilm formation in indwelling urinary catheters, antibiotic resistance patterns, and the detection methods of biofilm are briefly described. Understanding the mechanisms of biofilm formation and the antibiotic resistance patterns is of utmost importance which will result in the development of new remedies for biofilm infection.

Escaping from ESKAPE. Clinical Significance and Antibiotic Resistance Mechanisms in Acinetobacter baumannii: a Review

Antibiotic resistance represents a critical threat in clinical settings nowadays, with an essential ecological dimension. Due to the involvement of the resistance genes, this phenomenon has gained an unprecedented expansion. Their accumulation and dissemination are facilitated by mobile genetic elements (MGEs) (plasmids, transposons, integrons, genomic islands) that can increase intracellular DNA mobility. In clinical settings, one of the critical resistant bacteria associated with nosocomial infections is Acinetobacter baumannii. This Gram-negative bacterium exhibits variate resistance mechanisms that enable it to survive in extreme environmental conditions and to evade antimicrobial agents. The enormous adaptive capacity and the essential role in the emergence of severe nosocomial infections lead to the need to study more deeply the mechanisms involved in antibiotic resistance in A. baumannii strains. In this review, we will initially present the role of A. baumannii in human and veterinary infectious pathology. We will subsequently discuss the main genetic resistance mechanisms (both intrinsic and acquired) encountered in A. baumannii strains.

Human Leukocyte Antigen-DR Deficiency and Immunosuppression-Related End-Organ Failure in SARS-CoV2 Infection.

Human Leukocyte Antigen-DR Deficiency and Immunosuppression-Related End-Organ Failure in SARS-CoV2 Infection.

Detection of Metalo-Beta-Lactamase Gene in Carbapenem Resistant Pseudomonas Aeruginosa Isolated From Lahore, Pakistan

Pseudomonas aeruginosa is a widespread organism, caused severe nosocomial infection in human andassociated with multiple drug resistance (MDR) Objective: The present study was carried out to observecurrent antimicrobial resistant pattern of Pseudomonas aeruginosa in Lahore and to detect the Metallobeta-lactamase (MBL) gene in carbapenem resistant Pseudomonas aeruginosa Methods: By screening360 samples total 123 Pseudomonas aeruginosa was identified by standard microbiology techniques suchas microscopy and biochemical testing. The isolated Pseudomonas aeruginosa was evaluated for drugresistance by disc diffusion method and polymerase chain reaction (PCR) was used to identify thecarbapenem resistance causing gene (bla-VIM and bla-IMP) Results: Following antibiotic resistantpattern was observed, Gentamycin (59.00%), Ceftazidime (58.7%), Ceftriaxone (58.00%), Cefotazime(57.0%) and Ciprofloxacin (55.00%). Resistance rates to carbapenem group of antibiotics is Doripenem(30.5%) Meropenem (31.0%) and Imipenem (28.0%). Out of 123 samples of Pseudomonas aeruginosa, 28isolates were found resistant to carbapenem group of antibiotic which was supposed to be highlysensitive for this bacterium. Molecular based identification of resistance genes showed that bla-IMP genewas present in 32.1% (09) and bla-VIM was found positive in 17.8% (04) samples. Metallo-beta-lactamasesproducing genes (bla-VIM and bla-IMP), among carbapenem resistant Pseudomonas aeruginosa weredetected in 28.1% of samples. If other carbapenem resistant gene were also included this number mightbe higher Conclusions: PCR based test should be included in routine laboratory examination for quickdetection of the resistance causing genes.

Antibiotic Resistance Profiles, Molecular Mechanisms and Innovative Treatment Strategies of Acinetobacter baumannii.

Antibiotic resistance is one of the biggest challenges for the clinical sector and industry, environment and societal development. One of the most important pathogens responsible for severe nosocomial infections is Acinetobacter baumannii, a Gram-negative bacterium from the Moraxellaceae family, due to its various resistance mechanisms, such as the β-lactamases production, efflux pumps, decreased membrane permeability and altered target site of the antibiotic. The enormous adaptive capacity of A. baumannii and the acquisition and transfer of antibiotic resistance determinants contribute to the ineffectiveness of most current therapeutic strategies, including last-line or combined antibiotic therapy. In this review, we will present an update of the antibiotic resistance profiles and underlying mechanisms in A. baumannii and the current progress in developing innovative strategies for combating multidrug-resistant A. baumannii (MDRAB) infections.

The Construction of Carbon Nanotubes Containing an Anti-Bacterial Chemical Component and its Effect on MDR and XDR Isolates of Pseudomonas Aeruginosa

Pseudomonas aeruginosa is an opportunistic human pathogen that causes severe acute and chronic nosocomial infections, especially in immunocompromised burn patients. and can lead to severe mortality and morbidity. The emergence of antibiotic resistant P. aeruginosa infections has created significant challenges in treating these patients. A potential alternative treatment for antibiotic resistant pathogens includes the use of carbon nanotubes (CNTs), which have received considerable attention due to their potent antibacterial activity. The aim of this study was to construct a novel CNT containing an anti-bacterial chemical component to effectively combat drug resistant P. aeruginosa infections. In this study, a novel chemical component was synthesized and coated the CNT. The antimicrobial effects were then evaluated on MDR, XDR, and PDR strains of P. aeruginosa isolated from burn patients. Antibiotic susceptibility was evaluated using the disk diffusion test and minimum inhibitory concentration (MIC) testing. In order to determine the potential cytotoxicity, an MTT assay was performed on Human Dermal Fibroblasts. The effect of treatment on the expression of wound healing genes was analyzed via qRT-PCR. Experimental data indicates that our CNT coated chemical compound had antibacterial properties, negligible cytotoxicity, and could accelerate the wound healing process. Given the antibacterial properties of our CNT chemical compound, it has the potential to treat and reduce the occurrence of multi-drug resistant P. aeruginosa burn wound infections and aid in wound healing by turning on genes (VEGFA, EGF and PDEGF) involved in the wound healing process.

Intradural Extramedullary Tumor Causing Compression of the Thoracic and Lumbar Vertebrae in a 22-year-old Male with Acute Myeloid Leukemia

Myeloid sarcoma, characterized by the presence of immature myeloid cells occurring at an extramedullary site, is a rare manifestation of acute myelogenous leukemia (AML). Spinal cord compression as an initial presentation of AML is very rare with only a few reported cases. We discuss a case of a 22-year-old male who presented with bicytopenia and paraplegia. Workups were consistent with AML with monocytic differentiation. Chromosomal analysis revealed loss of Y and t (8;21). Spinal cord MRI showed intradural extramedullary-enhancing soft tissue lesions at levels T2 to T7 and L5 to S1, suspected to be myeloid sarcoma. Patient, however, succumbed to severe nosocomial infection prior to initiation of chemotherapy and radiotherapy.

Genomic analysis of 40 prophages located in the genomes of 16 carbapenemase-producing clinical strains of Klebsiella pneumoniae.

Klebsiella pneumoniae is the clinically most important species within the genus Klebsiella and, as a result of the continuous emergence of multi-drug resistant (MDR) strains, the cause of severe nosocomial infections. The decline in the effectiveness of antibiotic treatments for infections caused by MDR bacteria has generated particular interest in the study of bacteriophages. In this study, we characterized a total of 40 temperate bacteriophages (prophages) with a genome range of 11.454–84.199 kb, predicted from 16 carbapenemase-producing clinical strains of K. pneumoniae belonging to different sequence types, previously identified by multilocus sequence typing. These prophages were grouped into the three families in the order Caudovirales (27 prophages belonging to the family Myoviridae, 10 prophages belonging to the family Siphoviridae and 3 prophages belonging to the family Podoviridae). Genomic comparison of the 40 prophage genomes led to the identification of four prophages isolated from different strains and of genome sizes of around 33.3, 36.1, 39.6 and 42.6 kb. These prophages showed sequence similarities (query cover >90 %, identity >99.9 %) with international Microbe Versus Phage (MVP) (http://mvp.medgenius.info/home) clusters 4762, 4901, 3499 and 4280, respectively. Phylogenetic analysis revealed the evolutionary proximity among the members of the four groups of the most frequently identified prophages in the bacterial genomes studied (33.3, 36.1, 39.6 and 42.6 kb), with bootstrap values of 100 %. This allowed the prophages to be classified into three clusters: A, B and C. Interestingly, these temperate bacteriophages did not infect the highest number of strains as indicated by a host-range assay, these results could be explained by the development of superinfection exclusion mechanisms. In addition, bioinformatic analysis of the 40 identified prophages revealed the presence of 2363 proteins. In total, 59.7 % of the proteins identified had a predicted function, mainly involving viral structure, transcription, replication and regulation (lysogenic/lysis). Interestingly, some proteins had putative functions associated with bacterial virulence (toxin expression and efflux pump regulators), phage defence profiles such as toxin–antitoxin modules, an anti-CRISPR/Cas9 protein, TerB protein (from terZABCDE operon) and methyltransferase proteins.

Molecular characterization of carbapenem-resistant Klebsiella pneumoniae ST14 and ST512 causing bloodstream infections in ICU and surgery wards of a tertiary university hospital of Verona (northern Italy): co-production of KPC-3, OXA-48, and CTX-M-15 β-lactamases

Klebsiella pneumoniae strain is an important opportunistic pathogen that causes severe nosocomial infections. In the present study a molecular characterization of carbapenem resistant K. pneumoniae, isolated from blood samples of hospitalized patients of Verona University Hospital, was performed. The simultaneous presence of SHV-1/CTX-M-15/KPC-3 and SHV-1/CTX-M-15/OXA-48 serin-β-lactamases was ascertained in the 89% and 11% of K. pneumoniae ST512 and K. pneumoniae ST14, respectively. Molecular characterization of bla genes showed that blaKPC-3 was found in Tn4401a transposon with the tnpR, tnpA, ISKpn6, and ISKpn7 mobile elements whereas blaCTX-M-15 was detected downstream ISEcp1 genetic element. A class 1 integron with a gene cassette of 780 bp corresponding to aadA2 gene was identified in 33 K. pneumoniae ST512 isolates.

Isolation, Characterization, and Inactivation of Stenotrophomonas maltophilia From Leafy Green Vegetables and Urban Agriculture Systems

Stenotrophomonas maltophilia is an emerging opportunistic pathogen that, on the one hand, causes severe nosocomial infection in immunocompromised populations with a high mortality rate and, on the other hand, is present ubiquitously in the environment. This study, for the first time to the best of our knowledge, isolated and characterized S. maltophilia from leafy green vegetables produced by hydroponic farms and from a hydroponic farming facility in Singapore. Eleven S. maltophilia isolates were obtained from three types of leafy green vegetables (sweet basil, kale, and parsley) and from the nutrient solution used by a hydroponic farm. The antimicrobial resistance (AMR), biofilm-forming ability, and resistance to UV and quaternary ammonium compound (QAC) treatments were investigated, as was the fate of S. maltophilia in a simulated leafy green vegetable environment during a storage period of 6 days at different temperatures. The results showed that high population levels of S. maltophilia could be reached on leafy green vegetables, especially after being stored at abused temperatures (>8-log CFU/ml in basil juice after 6 days storage at 20°C) and on hydroponic farming facilities, probably due to biofilm formation (8 to 9-log CFU/well in biofilms). At 4°C, S. maltophilia was able to survive, but no growth was observed during storage in either bacteria culture media or basil juice for a period of 6 days. UV treatment, which induced substantial reductions in S. maltophilia in both single-species and dual-species biofilms mixed with Salmonella enterica serovar Typhimurium reference strain (ATCC 14028) or self-isolated Pseudomonas fluorescens (>4-log reductions by 250 mJ/cm2 UV), is recommended for employment by hydroponic farms to treat their nutrient solutions and farming facilities so as to enhance microbial safety.

Genomic analysis of a pan-resistant Klebsiella pneumoniae sequence type 11 identified in Japan in 2016

BackgroundKlebsiella pneumoniae (K. pneumoniae) carbapenemase (KPC)-producing K. pneumoniae has rapidly expanded and is associated with severe nosocomial infections. Last-line antibiotics, such as colistin and tigecycline, remain the only treatment option. This study described the genetic background of a novel pan-resistant KPC-producing K. pneumoniae isolate from Tokyo, Japan. MethodsThe antibiotic susceptibility of clinical isolates from a patient hospitalised in 2016 was tested using a MicroScan WalkAway instrument and the broth microdilution method. Susceptibility was defined according to breakpoints provided by the Clinical and Laboratory Standards Institute. Whole-genome sequencing was performed to detect acquired resistance genes and gene mutations. ResultsThe isolates were identified as part of a laboratory stool and swab surveillance-screening program for infection control. The carbapenem-resistant strain was resistant to β-lactams, including broad-spectrum cephalosporins and carbapenems, and to aminoglycosides, chloramphenicol, fosfomycin, fluoroquinolones, polymyxins, tetracyclines, and trimethoprim/sulfamethoxazole. The K. pneumoniae isolate harboured a plasmid carrying fosA3, rmtB, blaCTX-M-65, blaSHV-12, and blaKPC-2 in a non-Tn4401 mobile element. Colistin resistance was associated with a mutation in the mgrB gene, which regulates PhoP/PhoQ. The K. pneumoniae isolate belongs to sequence type 11, which is a successful epidemic-type strain. ConclusionThis study identified molecular resistance markers in a pan-resistant isolate and provided a genomic description of the pan-resistance and origins of the isolate and plasmid. The isolate is closely related to a recent highly pathogenic carbapenem-resistant K. pneumoniae identified in China; however, it lacks a virulence plasmid (but it could still act as a reservoir for a virulence plasmid). This K. pneumoniae isolate is of concern in hospital and community care settings.

Novel Sequence Type in Bacillus cereus Strains Associated with Nosocomial Infections and Bacteremia, Japan.

Bacillus cereus is associated with foodborne illnesses characterized by vomiting and diarrhea. Although some B. cereus strains that cause severe extraintestinal infections and nosocomial infections are recognized as serious public health threats in healthcare settings, the genetic backgrounds of B. cereus strains causing such infections remain unknown. By conducting pulsed-field gel electrophoresis and multilocus sequence typing, we found that a novel sequence type (ST), newly registered as ST1420, was the dominant ST isolated from the cases of nosocomial infections that occurred in 3 locations in Japan in 2006, 2013, and 2016. Phylogenetic analysis showed that ST1420 strains belonged to the Cereus III lineage, which is much closer to the Anthracis lineage than to other Cereus lineages. Our results suggest that ST1420 is a prevalent ST in B. cereus strains that have caused recent nosocomial infections in Japan.