Pathogen In Nosocomial Infections Research Articles

Rapid Analysis for Staphylococcus aureus via Microchip Capillary Electrophoresis.

Staphylococcus aureus (S. aureus) is one of the most common pathogens for nosocomial and community infections, which is closely related to the occurrence of pyogenic and toxic diseases in human beings. In the current study, a lab-built microchip capillary electrophoresis (microchip CE) system was employed for the rapid determination of S. aureus, while a simple-to-use space domain internal standard (SDIS) method was carried out for the reliable quantitative analysis. The precision, accuracy, and reliability of SDIS were investigated in detail. Noted that these properties could be elevated in SDIS compared with traditional IS method. Remarkably, the PCR products of S. aureus nuc gene could be identified and quantitated within 80 s. The theoretical detection limit could achieve a value of 0.066 ng/μL, determined by the using SDIS method. The current work may provide a promising detection strategy for the high-speed and highly efficient analysis of pathogens in the fields of food safety and clinical diagnosis.

Evaluation of the Immunochromatographic NG-Test Carba 5, RESIST-5 O.O.K.N.V., and IMP K-SeT for Rapid Detection of KPC-, NDM-, IMP-, VIM-type, and OXA-48-like Carbapenemase Among Enterobacterales.

BackgroundEnterobacterales are the most common pathogens for nosocomial infections. The emergence and spread of KPC, NDM, and OXA-48-like carbapenemase-producing Enterobacterales with their extensively drug-resistant characteristics have posed great threats to public health. This study aimed to evaluate the performance of NG-test Carba 5, RESIST-5 O.O.K.N.V., and IMP K-SeT for rapid detection of five carbapenemases (KPC, NDM, VIM, IMP, and OXA-48-like) among Enterobacterales.MethodsA total of 186 carbapenem-resistant Enterobacterales clinical isolates and 29 reference strains were used in this study. Carbapenemase genes were confirmed by PCR and DNA sequencing. The sensitivities and specificities of these assays were calculated utilizing the VassarStats software.ResultsFor clinical isolates, the NG-test Carba 5 detected KPC, NDM, OXA-48-like, IMP, and VIM in less than 15 min with the sensitivity and specificity of 100% and 100%, respectively. The RESIST-5 O.O.K.N.V. detected KPC, NDM, OXA-48-like, and VIM with the sensitivity and specificity of 99.4 and 100%. The IMP K-SeT detected all of the IMP producers (6/6). For reference strains, the sensitivity and specificity of NG-test Carba 5, RESIST-5 O.O.K.N.V., and IMP K-SeT were all 100 and 100%, respectively.ConclusionAs efficient, rapid, and convenient diagnostic methods, NG-test Carba 5, RESIST-5 O.O.K.N.V., and IMP K-SeT could help to simplify the complex routine workflow for detecting carbapenemases. Rapid and accurate identification of carbapenemase is of significance for both epidemiological and infection control purposes.

Sonoelectrochemical Synthesis of Silver Nanoparticles in Sodium Polyacrylate Solution

The paper shows the effectiveness of a “green” synthesis of silver nanoparticles (AgNPs) in sodium polyacrylate (NaPA) solutions by sonoelectrochemical method using silver sacrificial anodes. Using the cyclic voltammetry in the ultrasonic field in the range of E from 1.0 to -1.0 V, the temperature and NaPA concentration are the main parameters influencing the rate of synthesis and the size of AgNPs. As these parameters increase, the rate of nanoparticle synthesis increases. According to TEM studies, with increasing temperature and decreasing NaPA concentration, there is a tendency to increase the size of AgNPs. However, in all of the cases, the size of AgNPs does not exceed 30 nm. Using the UV–Vis spectroscopy, it was found that the position of the absorption peak at c.a. 500 nm, corresponding to the silver nanoparticles, is practically not shifted during numerous cycles. This fact may indicate the stability of sonoelectrochemical synthesis of AgNPs in time. Synthesized AgNPs revealed high antibacterial activity against gram-positive and gram-negative strains of typical pathogens of nosocomial infections, demonstrating the prospect of using sonoelectrochemical technique for obtaining silver colloids as a component of bactericidal drugs.

The predictive factors for poor outcomes in preterm infants with coagulase-negative staphylococci infection

Background: The main pathogen for neonatal nosocomial infections is coagulase-negative staphylococci (CoNS), particularly in very low-birth-weight and premature newborns. The current study is aimed to assess the outcomes of preterm infants with CoNS infection via a retrospective analysis, to determine the correlation between the clinical profile and mortality and morbidity, and to determine the factors associated with poor outcomes. Materials and Methods: This retrospective case–control study was conducted in the Children's and Women's Health Centre of King Fahad Medical City neonatal intensive care unit in Saudi Arabia. The study period was from January 2013 to December 2019. Results: There were 1333 controls and 137 cases of CoNS infection. There was a significant association between total parenteral nutrition use, surgical insertion of a central line, inotrope use, and spontaneous intestinal perforation and CoNS infection. There was a significant association between umbilical vein catheter (UVC) and peripherally inserted central catheter (PICC) line use and CoNS infection. The use of a UVC or PICC line significantly impacted. The presence of patent ductus arteriosus also significantly impacted. Conclusions: There was a significant association between UVC and PICC line use and outcome. The presence of patent ductus arteriosus or a perforated bowel and the need for inotrope use in CoNS infection was associated with poor outcomes. Mortality, retinopathy of prematurity, and necrotizing enterocolitis requiring surgery were more common in infants with CoNS infections.

Synergistic antimicrobial activity of a novel cationic micelle L/D2 and imipenem against multidrug-resistant Acinetobacter baumannii.

Background: The multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) has become one of the most important pathogens of nosocomial infection due to widespread use of broad spectrum antimicrobial drugs and immunosuppressor therapy. As polymyxins resistance emerges, developing novel effective antibacterial agents capable of overcoming multidrug resistance is urgently needed. Methods: In this study, biodegradable triblock copolymers of polyethylene glycol (PEG), guanidinium-functionalized polycarbonate and polylactide, PEG-PGC20-PLLA20 (L2) and PEG-PGC20-PDLA20 (D2), were utilized as antibacterial agents. Results: The copolymers self-assemble into micellar nanoparticles (L/D2), and exhibit broad-spectrum antibacterial activity against 20 clinically isolated multidrug-resistant A. baumannii strains. L/D2 had more rapid killing kinetics than conventional antibiotics imipenem and ceftazidime, and exhibited potent anti-biofilm activity. Repeated use of L/D2 did not induce drug resistance. From scanning electron microscopy and nucleic acid release analyses, L/D2 showed membrane-lytic mechanism. We also demonstrated that L/D2 was synergistically active with imipenem against MDR A. baumannii strains. Additionally, strong synergistic antibacterial activity was also observed for the combined use of L/D2 and imipenem in a MDR A. baumannii abdominal infection mouse model. Conclusions: Therefore, the combination of L/D2 and imipenem might be an alternative option for the prevention of nosocomial infection caused by A. baumannii.

EPIDEMIOLOGY OF NOSOCOMIAL INFECTION COMPLICATIONS IN A SURGICAL CLINIC

The analysis of the data of literary sources of domestic and foreign researchers on the problem of the occurrence and development of nosocomial infections in general and in the surgical departments in particular is carried out. The relevance of the study is confirmed by the following data: the spread of nosocomial infections in the Russian Federation is 2.5 million annually; the minimum damage inflicted by them in Russia alone is approximately 6-7 million rubles. The data of foreign scientists have been studied, suggesting that infections in the field of hirirurgic intervention were recorded in 13% of cases after performing clean operations, in 16% after and in 29% after . In St. Petersburg, with selective studies, the frequency of infections in the field of surgical intervention revealed 9% of patients among 1,500 operated It was revealed that the number of potential causative agents of nosocomial infections increases every year due to opportunistic bacteria that differ in biological characteristics from hospital strains and have multiple drug antibiotic resistance. A retrospective and prospective analysis of the frequency of occurrence of microorganisms in patients of the surgical department of 2008-2019 was carried out. The microbial spectrum and prevalence of nosocomial infection pathogens in the surgical department were investigated. An epidemiological analysis of the causative agents of nosocomial infection in patients with pneumonia, infections in the surgical field and urinary tract, as well as with generalized infections, was carried out. The analysis of the bacterial flora of the clinical microbiological culture of the wound discharge, sputum, urine and blood was carried out. The following microorganisms were most prevalent in these samples: Staphylococcus aureus, Acinetobacter baumannii, Candida albicans, Klebsiella pneumonia. A tendency to increase the proportion of Candida albicans in patients of the surgical department, as well as a high prevalence of Staphylococcus epidermidis in blood cultures, was revealed.

First report of cross resistance to silver and antibiotics in Klebsiella pneumoniae isolated from patients and polluted water in Tunisia

AbstractKlebsiella pneumoniae, ubiquitously found in a variety of environmental sources, is an important pathogen in burn wounds and nosocomial infections. Burn wounds have been commonly treated with silver compounds, which are also used in a multitude of (non)medical products. As the latter increased silver discharge into different environments, we evaluated and compared silver resistance in K. pneumoniae isolates collected from patients hospitalized at the Charles‐Nicolle hospital (Tunis, Tunisia) with isolates collected from different metal polluted waters in the north and south of Tunisia. All K. pneumoniae isolates harboured blaTEM‐1 and blaSHV‐1. In addition, all clinical isolates showed a multidrug phenotype and harboured the blaCTX‐M‐15, blaOXA‐1 and blaNDM‐1. Furthermore, all isolates showed resistance to silver nitrate. The silver resistance determinant, screened via the silE gene, was located for all isolates on a large plasmid with a size similar to pMG101. This study showed cross‐resistance between silver and beta‐lactams in clinical as well as environmental K. pneumoniae isolates from Tunisia and showed for the first time that NDM‐1‐producing K. pneumoniae developed resistance to silver.

Видовий склад збудників нозокоміальних інфекцій у відділенні реанімації та інтенсивної терапії (для хірургічних хворих) Національного військово-медичного клінічного центру «Головний військовий клінічний госпіталь»

SummaryThe purpose of the work is to identify the causative agents of nosocomial bacterialinfections for the rational appointment of antibiotic therapy and monitoring of thecurrent situation with the microflora in patients at the Intensive care unit (for surgicalpatients). To study the microbiological passport of the Intensive care unit (for surgicalpatients) of the National Military Medical Clinical Center «Main Military ClinicalHospital» for further use of the results in rational antibiotic therapy and slowing thedevelopment of antibiotic resistance.Material and methods. We analyzed the results of microbiological research of 631samples of clinical material from patients who were treated in the Intensive care unit(for surgical patients) during 2018.Conclusions. The study results indicate the presence of features of microbiallandscape pathogens of nosocomial infections at the Intensive care unit (for surgicalpatients). These include mainly Ps.aeruginosa, Kl.pneumonia, E.coli. It is necessary toconduct microbiological monitoring of the landscape of pathogens of nosocomialinfections and their sensitivity to antibiotics in order to implement actions aimed toincrease the efficiency of the treatment process and reduce the rate of development ofantibiotic resistance.

Characteristic and role of chromosomal type II toxin-antitoxin systems locus in Enterococcus faecalis ATCC29212.

The Gram-positive bacterium Enterococcus faecalis is currently one of the major pathogens of nosocomial infections. The lifestyle of E. faecalis relies primarily on its remarkable capacity to face and survive in harsh environmental conditions. Toxin-antitoxin (TA) systems have been linked to the growth control of bacteria in response to adverse environments but have rarely been reported in Enterococcus. Three functional type II TA systems were identified among the 10 putative TA systems encoded by E. faecalis ATCC29212. These toxin genes have conserved domains homologous to MazF (DR75_1948) and ImmA/IrrE family metallo-endopeptidases (DR75_1673 and DR75_2160). Overexpression of toxin genes could inhibit the growth of Escherichia coli. However, the toxin DR75_1673 could not inhibit bacterial growth, and the bacteriostatic effect occurred only when it was coexpressed with the antitoxin DR75_1672. DR75_1948-DR75_1949 and DR75_160-DR75_2161 could maintain the stable inheritance of the unstable plasmid pLMO12102 in E. coli. Moreover, the transcription levels of these TAs showed significant differences when cultivated under normal conditions and with different temperatures, antibiotics, anaerobic agents and H2O2. When DR75_2161 was knocked out, the growth of the mutant strain at high temperature and oxidative stress was limited. The experimental characterization of these TAs loci might be helpful to investigate the key roles of type II TA systems in the physiology and environmental stress responses of Enterococcus.

In vitro activity of biofilm inhibitors in combination with antibacterial drugs against extensively drug-resistant Acinetobacter baumannii

Acinetobacter baumannii is a common pathogen of nosocomial infection, and its ability to form biofilms further contributes to its virulence and multidrug resistance, posing a great threat to global public health. In this study, we investigated the inhibitory effects of five biofilm inhibitors (BFIs) (zinc lactate, stannous fluoride, furanone, azithromycin, and rifampicin) on biofilm formation of nine extensively drug-resistant A. baumannii (XDRAB), and assessed the synergistic antibacterial effects of these BFIs when combined with one of four conventional anti-A. baumannii antibiotics (imipenem, meropenem, tigecycline, and polymyxin B). Each of the five BFIs tested was found to be able to significantly inhibit biofilm formation of all the clinical isolates tested under sub-minimal inhibitory concentrations. Then, we observed synergistic effects (in 22%, 56% and 11% of the isolates) and additive effects (56%, 44% and 44%) when zinc lactate, stannous fluoride and furanone were combined with tigecycline, respectively. When zinc lactate and stannous fluoride were each used with a carbapenem (imipenem or meropenem), in 33% and 56–67% of the isolates, they showed synergistic and additive effects, respectively. Additivity in > 50% of the isolates was detected when rifampicin was combined with imipenem, meropenem, tigecycline, or polymyxin B; and a 100% additivity was noted with azithromycin-polymyxin B combination. However, antagonism and indifference were noted for polymyxin B in its combination with zinc lactate and stannous fluoride, respectively. In conclusion, five BFIs in combination with four antibacterial drugs showed different degrees of in vitro synergistic and additive antibacterial effects against XDRAB.

Three-year epidemiological analysis of Clostridioides difficile infection and the value of hospital-infection control measures in a tertiary-care teaching hospital in Japan using PCR-based open-reading frame typing

IntroductionClostridioides difficile is an important causative pathogen in antibiotic-associated colitis and nosocomial infections. This study aimed to assess immunochromatographic test results for C. difficile infection and the utility of PCR-based open-reading frame typing (POT) for potentially controlling the intra-ward transmission of C. difficile. MethodsWe conducted a molecular epidemiological analysis using POT to investigate 102 inpatients who tested positive for the C. difficile toxin using immunochromatography in a tertiary-care teaching hospital in Japan between 2016 and 2018; isolates from the patients were obtained and cultured. ResultsThe number of POT numbers detected in 2016, 2017, and 2018 were 27 (among 34 patients), 20 (among 31 patients), and 28 (among 37 patients), respectively. During this three-year period, there were seven cases whose bacterial strains with the same POT number was identified in the same ward within 6 months. The intra-ward transmission rate was the highest in 2017 (16.1%). Intra-ward transmission was identified at a higher rate in patients whose sample cultures tested toxin-positive than in patients whose sample cultures tested toxin- and glutamate-dehydrogenase-positive via immunochromatography (16% vs. 3%, p < 0.05). ConclusionsWe conclude that the use of immunochromatographic tests for C. difficile diagnosis and epidemiological analyses via POT may be helpful for evaluating intra-ward transmission of C. difficile.

Benzyl isocyanate isolated from the leaves of Psidium guajava inhibits Staphylococcus aureus biofilm formation

Benzyl isocyanate (BIC), from methanol extract of Psidium guajava leaves, exhibited substantial anti-biofilm activities against Staphylococcus aureus, the common bacterial pathogen in nosocomial infections. Major components of the extract included eugenol, BIC, phenyl-2-methoxy-4-(1-propenyl)-acetate and 2,5-pyrrolidinedione,1-penta-3-4-dienyl, analyzed by GC-MS and HPLC studies. BIC exhibited substantial anti-biofilm activitiy against S. aureus, established by assaying biofilm formation, biofilm metabolic activity, bacterial adherence to hydrocarbons, exopolysaccharide formation, and optical and scanning electron microscopic studies. BIC significantly downregulated the important biofilm markers of S. aureus, viz., icaAD, sarA and agr, observed by quantitative real time polymerase chain reaction analysis. Molecular docking studies revealed thermodynamically favorable interaction of BIC with IcaA, SarA and Agr, having Gibbs energy values of −8.45, −9.09 and −10.29 kcal mol−1, respectively. BIC after binding to IcaR, the repressor of IcaA, influences its binding to target DNA site (Eshape, −157.27 kcal mol−1). The results are considered to demonstrate anti-biofilm potential of BIC against bacterial infections.

Mathematical basis for the assessment of antibiotic resistance and administrative counter-strategies.

Diversity as well as temporal and spatial changes of the proportional abundances of different antibiotics (cycling, mixing or combinations thereof) have been hypothesised to be an effective administrative control strategy in hospitals to reduce the prevalence of antibiotic-resistant pathogens in nosocomial or community-acquired infections. However, a rigorous assessment of the efficacy of these control strategies is lacking. The main purpose here is to present a mathematical framework for the assessment of control stategies from a processual stance. To this end, we adopt diverse measures of heterogeneity and diversity of proportional abundances based on the concept of entropy from other fields and adapt them to the needs in assessing the impact of variations in antibiotic consumption on antibiotic resistance. Thereby, we derive a family of diversity measures whose members exhibit different degrees of complexity. Most important, we extent these measures such that they account for the assessment of temporal changes in heterogeneity including otherwise undetected diversity-invariant permutations of antibiotics consumption and prevalence of resistant pathogens. We apply a correlation analysis for the assessment of associations between changes of heterogeneities on the antibiotics and on the pathogen side. As a showcase, which serves as a proof-of-principle, we apply the derived methods to records of antibiotic consumption and prevalence of antibiotic-resistant germs from University Hospital Dresden (cf. supplement "DiebnerEtAl_Data-Supplement"). Besides the quantification of heterogeneities of antibiotics consumption and antibiotic resistance, we show that a reduction of prevalence of antibiotic-resistant germs correlates with a temporal change of similarity with respect to the first observation of antibiotics consumption, although heterogeneity remains approximately constant. Although an interventional study is pending, our mathematical framework turns out to be a viable concept for the assessment and optimisation of control strategies intended to reduce antibiotic resistance.

Development of novel dual-action coatings with osteoinductive and antibacterial properties for 3D-printed titanium implants

Gallium (Ga) has been recently proposed as a novel therapeutic agent, since it promotes bone formation and exhibits antibacterial properties. This work focuses on the optimization of a thermochemical treatment that incorporates Ga ions by the addition of the body-friendly Ga nitrate approved by the Food and Drug Administration. The objective was to simultaneously provide the inner and the outer surfaces of porous‑titanium surfaces obtained by 3D-printing with bioactivity and antibacterial properties. The apatite-forming ability of the coating, as well as the antibacterial activity and SaOS-2 cell adhesion, proliferation, differentiation and mineralization were evaluated and compared with untreated Ti surfaces. The characterization of the surfaces revealed the presence of a Ga-containing calcium titanate layer, which was non cytotoxic and in simulated body fluid produced a homogeneous apatite coating well adhered to the substrate. The formation of this apatite layer was accelerated with increasing Ga amounts present on the surface, resulting also in an increase in thickness. An initial quick release of Ga ion promoted the antibacterial effect against gram positive strains, especially for Pseudomonas aeruginosa, one of the most frequent resistant pathogens in nosocomial infections. SaOS-2 cells adhered and proliferated on the Ga-doped Ti surfaces, its presence contributed to cell differentiation and to considerably increase the mineralization levels. Thus, the developed multifunctional coatings could provide bioactivity to the porous Ti implants while protecting them from the most frequent gram-negative pathogens.

Antagonistic and antioxidant potencies of Centrosema pubescens benth extracts against nosocomial infection pathogens

Abstract The plant Centrosema pubescens that belongs to the Fabaceae family is characterized by herbaceous, twinning, and climbing stem. The main objective of this study is to investigate the phytochemicals of C. pubescens and establish its bioprospection analysis. The preparations of crude extract of leaf stem and flower parts of the samples were done with the Soxhlet apparatus. The solvent extracts of C. pubescens containing different phytochemical contents are investigated for biological activities using the standard procedure. In the HPLC analysis, the active substance is eluted from the extract that shows the best results in nutritional and antioxidant assays among the various solvents. The solvent extracts show rich nutritional parameters. The antimicrobial assay shows that the zone of clearance observed is maximum with value of 15 ± 0.50 mm in the leaf extract. The methanol extract of the leaf shows moderate activity with MIC value of 31.2 μg/ml. The IC50 value of DPPH, ABTS, and phosphomolybdenum assay is found to be 9.8 μg/ml, 10,191.6 ± 1.24 μM TE/g extract, and 56.04 ± 1.19 mg AA/g, respectively. Similarly, the methanol extract of the leaf shows strong antioxidant activity in the ABTS scavenging assay, and in the phosphomolybdenum, superoxide, and reducing power assay. The HPLC chromatograph and LC-MS studies show that quercetin is the active metabolite. This study is a baseline work and can be used in the future for the development of possible novel generation of drugs in the pharmaceutical industry. The overall result shows that the leaf extracts are better than the stem extracts.

Frequency of Vectors of Methicillin-resistant Staphylococcus Aureus Among Emergency Staff of Vali-e-Asr Hospital in Arak City, 2018

Background and Aim: Staphylococcus aureus is common pathogens of nosocomial infections. Nasal swabs in hospital staff is main sources of hospital infections are considered. The aim of this study was to determine the frequency of nasopharyngeal carriers of methicillin-resistant Staphylococcus aureus and microbial contamination of health care workers' cell phones in Emergency department of Vali-e-Asr Hospital in Arak City. Methods &amp; Materials: In this descriptive study, nose swabs and cell phone levels were taken from 70 health care workers in the emergency ward of Vali-e-Asr Hospital. The Staphylococcus aureus clinical isolates were identified using standard microbiological methods (catalase, coagulase, mannitol fermentation and DNase). The susceptibility to oxacillin and cefoxitin was detected by the disk diffusion and the mecA genes in this clinically isolated strain of staphylococci was investigated by Polymerase Chain Reaction (PCR). Ethical Considerations: This study was approved by the Research Ethics committee of Arak University of Medical Sciences. (Code : IR.ARAKMU.REC.1396.282). Results: According the results, Staphylococcus aureus was isolated in 16 cases, which 5 cases were methicillin-sensitive S. aureus (MSSA), and 11 cases were Methicillin resistant S. aureus (MRSA). Also, 3 cell phones were infected with Staphylococcus aureus, which 1 case was MRSA and 2 cases were MSSA. Conclusion: The results of this study showed that frequency of MSSA strains is significant in emergency personnel of the hospital. Thus, regarding to the risk of epidemics due to nosocomial infections, periodic testing for the identification and treatment of carriers among employees for controlling and preventing hospital infections seems necessary.

Comparative efficacy of hospital disinfectants against nosocomial infection pathogens

BackgroundDue to the increasing rate of hospital-acquired infections, it is essential to select appropriate disinfectant agents. In this study, the efficacy of hospital disinfectants against nosocomial infection pathogens was compared.MethodsHigh level disinfectants (Steranios 2%, Deconex HLDPA, and Microzed Quatenol) were tested for their antibacterial effects by determining their minimum inhibitory (MIC) and minimum bactericidal concentrations (MBC) against Enterococcus faecalis ATCC 29212 and Burkholderia cepacia ATCC 10673.ResultsE. faecalis, as gram-positive bacterium, was more susceptible to high level disinfectants compared to gram-negative B.cepacia. The MIC = MBC values of 2% Steranios, Deconex HLDPA and Microzed Quatenol against E. faecalis and B.cepacia were 0.31, 9.77, 2.2 mg/L and 9.8, 78.13, 70.31 mg/L, respectively.ConclusionsAccording to the findings of this study, the most effective disinfectants against both E. faecalis and B.cepacia were Steranios 2%, Microzed Quatenol, and Deconex HLDPA in order. Considering the importance of these bacterial strains in healthcare-associated infections, the use of these effective disinfectants is recommended in the hospitals.

Management and outcomes of Burkholderia cepacia complex bacteremia in patients without cystic fibrosis: a retrospective observational study.

Burkholderia cepacia complex (BCC) is an emerging pathogen of nosocomial infection in chronic or critically ill patients without cystic fibrosis (CF). The objective was to evaluate the management and outcomes of BCC bacteremia in patients without CF. We conducted a retrospective study of non-CF adult patients with BCC bacteremia between January 1997 and December 2016 at 4 tertiary hospitals in South Korea. A total of 216 non-CF patients with BCC bacteremia were identified. Most cases were hospital-acquired (79.2%), and the most common source was a central venous catheter (CVC) (42.1%). The rates of susceptibility to trimethoprim-sulfamethoxazole and piperacillin-tazobactam of BCC isolates were high as 92.8% and 90.3%, respectively. The rates of susceptibility to ceftazidime, meropenem, and levofloxacin were 75.5%, 72.3%, and 64.1%, respectively. The 14-day, 30-day, and in-hospital mortality rate was 19.4%, 23.1%, and 31.0%, respectively. Female (OR = 3.1; 95% CI, 1.4-6.8), liver cirrhosis (OR = 6.2; 95% CI, 1.6-16.6), septic shock (OR = 11.2; 95% CI, 5.1-24.8), and catheter-related infection (OR = 2.6, 95% CI, 1.2-5.8) were the independent risk factors for 30-day mortality. The outcome did not differ according to type of antibiotics used. Among 91 patients with CVC-related BCC bacteremia, delayed CVC removal (> 3days) had a higher rate of persistent bacteremia (54.5 vs. 26.1%; P = 0.03) and lower rate of clinical response (49.0 vs. 71.9%; P = 0.04), compared with early CVC removal (within 3days). BCC bacteremia occurring in non-CF patients was mostly hospital-acquired and CVC-related. Early removal of the catheter is crucial in treatment of CVC-related BCC bacteremia.

Distribution and Drug Sensitivity of Pathogens Causing Nosocomial Infection in Patients with Hematological Granulocytosis

To investigate the distribution and drug resistance of nosocomial infection pathogens in AL patients with hematological agranulocytosis, so as to provide evidence for the clinical rational use of antibiotics. Pathogenic data of 504 hospitalized patients with agranulocytosis caused by nosocomial infection in the Department of Hematology, the First Hospital of Lanzhou University from May 2015 to May 2018 were collected and retrospectively analyzed for the distribution of pathogenic bacteria and the results of drug susceptibility. The isolated pathogenic bacteria strains amounted to 184, out of which, 168 strains (91.3%) orginated from the patients with acute leukemia, while 16 strains (8.7%) originated from the patients with non-acute leukemia. The positive samples mainly originated from blood stream, the isolated bacteria from which were 81 straims (44%); then originated from sputam and pharynx swabs, from which isolated bacteria amounted to 54 strains (29.3%) and 35 strains (19%) respectively. In the pathogenic bacteria, the Gram-negative bacteria amounted to 126 strains accounting for 68.46%, out of which the most commond bacteria strains were Klebseilla pneumoniae, cscherichia coli and Pseudomonas aeruginosa; the Gram positive bocteria amounted to 23 strains accounting for 12.5%, mainly staphy lococeus anreus, and Staphylococcus epitermidis; the fungi amounted to 35 strains accounting for 19.02%, mainly Candida albicans. The detection rates of Escherichia coli and Klebsiella pneumoniae producing extended-spectrum β-lactamases (ESBLs) were 40.0% and 22.2%, respectively. They were 100% sensitive to amikacin and 27.8% resistant to carbapenems. Klebsiella pneumoniae had the highest sensitivity to amikacin, 94.44% to ampicillin, 97.22% to carbapenems and 100% sensitive to ammonia. Their penicillin-resistance rate was the highest, up to 80%; Pseudomonas aeruginosa was sensitive to the antibiotics (＞80%）. Methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus were detected in Gram-positive bacteria. The susceptibility rate of main Gram-positive bacteria to vancomycin and linezolid was 100%, and they were 100% resistant to penicillin. Gram-negative bacteria are the main pathogens of nosocomial infection in patients with hematological agranulocytosis. Pathogens have different resistance to antimicrobial agents. It is important to know the distribution and susceptibility of common pathogens for rational selection of antimicrobial agents and control of nosocomial infection.

Characterization of biofilm production in different strains of Acinetobacter baumannii and the effects of chemical compounds on biofilm formation.

Acinetobacter baumannii, an important emerging pathogen of nosocomial infections, is known for its ability to form biofilms. Biofilm formation increases the survival rate of A. baumannii on dry surfaces and may contribute to its persistence in the hospital environment, which increases the probability of nosocomial infections and outbreaks. This study was undertaken to characterize the biofilm production of different strains of A. baumannii and the effects of chemical compounds, especially antibiotics, on biofilm formation. In this study, no statistically significant relationship was observed between the ability to form a biofilm and the antimicrobial susceptibility of the A. baumannii clinical isolates. Biofilm formation caused by A. baumannii ATCC 17978 after gene knockout of two-component regulatory system gene baeR, efflux pump genes emrA/emrB and outer membrane coding gene ompA revealed that all mutant strains had less biofilm formation than the wild-type strain, which was further supported by the images from scanning electron microscopy and confocal laser scanning microscopy. The addition of amikacin, colistin, LL-37 or tannic acid decreased the biofilm formation ability of A. baumannii. In contrast, the addition of lower subinhibitory concentration tigecycline increased the biofilm formation ability of A. baumannii. Minimum biofilm eradication concentrations of amikacin, imipenem, colistin, and tigecycline were increased obviously for both wild type and multidrug resistant clinical strain A. baumannii VGH2. In conclusion, the biofilm formation ability of A. baumannii varied in different strains, involved many genes and could be influenced by many chemical compounds.