Common Nosocomial Pathogens Research Articles

Whole-Genome Sequence of High-Risk Clone Sequence Type 111 of Pseudomonas aeruginosa Strain NUBRI-P, Isolated from a Wounded Sudanese Patient.

Pseudomonas aeruginosa is a common nosocomial pathogen often associated with a high mortality rate in vulnerable populations. Here, we describe the genomic sequence of a pan-resistant, high-risk clone of P. aeruginosa sequence type 111 (ST111) isolated from a hospital patient in Sudan.

Characterization of phenotypic and genotypic traits of carbapenem-resistant Acinetobacter baumannii clinical isolates recovered from a tertiary care hospital in Taif, Saudi Arabia.

Background and objectiveAcinetobacter baumannii (A. baumannii) is a common nosocomial pathogen, which developed multi-drug-resistance to different classes of antibiotics including carbapenems. This study examined ten common carbapenemase genes among 32 carbapenem-resistant A. baumannii clinical isolates recovered from Taif, Saudi Arabia.MethodsIsolates were phenotypically identified to the genus level by Vitek®2 and API 20NE®. The species level was confirmed by the amplification of blaOXA-51. The susceptibility for 21 different antibiotics was performed by Vitek 2 and modified Kirby-Bauer method. Isolates were genetically screened for 10 carbapenemases. Phylogenetic relatedness between isolates was determined by ERIC-PCR.ResultsGenotypically identified A. baumannii represented 100% of the total phenotypically identified Acinetobacter spp. All the carbapenem-resistant isolates were sensitive to polymyxin B and colistin. Among the other antibiotics, ampicillin/sulbactam and tigecycline were the most effective agents. 90.8% of the isolates were resistant to all ten investigated β–lactams. blaOXA-51, blaIPM, blaNDM and blaOXA-23 were detected in 100%, 87.5%, 62.5% and 59.4% of isolates, respectively. Also, blaVIM and blaOXA-40 were less prevalent and were detected in 9.3% and 3.1% of the isolates, respectively. In addition, blaKPC, blaOXA-48, blaOXA-58, blaOXA-181 were not detected in any isolate. The A. baumannii isolates were categorised into ten genotypes on the basis of the detected carbapenemase genes and ERIC-PCR revealed a remarkable clonal diversity among these isolates.ConclusionClass A and class D carbapenemase genes were the most commonly detected among carbapenem resistant A. baumannii (CRAB) clinical isolates.

A trivalent vaccine consisting of “flagellin A+B and pilin” protects against Pseudomonas aeruginosa infection in a murine burn model

Pseudomonas aeruginosa is a common nosocomial pathogen in burn patients, and rapidly achieves antibiotic resistance, and thus, developing an effective vaccine is critically important for combating P. aeruginosa infection. Flagella and pili play important roles in colonization of P. aeruginosa at the burn wound site and its subsequent dissemination to deeper tissue and organs. In the present study, we evaluated protective efficacy of a trivalent vaccine containing flagellins A and B (FlaA + FlaB) + pilin (PilA) in a murine burn model of infection. “FlaA + FlaB + PilA” induced greater protection in P. aeruginosa murine burn model than the single components alone, and it showed broad immune protection against P. aeruginosa strains. Immunization with “FlaA + FlaB + PilA” induced strong opsonophagocytic antibodies and resulted in reduced bacterial loads, systemic IL-12/IL-10 cytokine expression, and increased survival after challenge with three times lethal dose fifty (LD50) of P. eruginosa strains. Moreover, the protective efficacy of “FlaA + FlaB + PilA” vaccination was largely attributed to specific antibodies. Taken together, these data further confirm that the protective effects of “FlaA + FlaB + PilA” vaccine significantly enhance efficacy compared with antibodies against either mono or divalent antigen, and that the former broadens the coverage against P. eruginosa strains that express two of the three antigens.

Exogenous acquisition of Pseudomonas aeruginosa in intensive care units: a prospective multi-centre study (DYNAPYO study)

Pseudomonas aeruginosa remains one of the most common nosocomial pathogens in intensive care units (ICUs). Although exogenous acquisition has been widely documented in outbreaks, its importance is unclear in non-epidemic situations. To elucidate the role of exogenous origin of P.aeruginosa in ICU patients. A chronological analysis of the acquisition of P.aeruginosa was performed using samples collected in 2009 in the DYNAPYO cohort study, during which patients and tap water were screened weekly. Molecular relatedness of P.aeruginosa isolates was investigated by pulsed-field gel electrophoresis. Exogenous acquisition was defined as identification of a P.aeruginosa pulsotype previously isolated from another patient or tap water in the ICU. The DYNAPYO cohort included 1808 patients (10,402 samples) and 233 water taps (4946 samples). Typing of 1515 isolates from 373 patients and 375 isolates from 81 tap water samples identified 296 pulsotypes. Analysis showed exogenous acquisition in 170 (45.6%) of 373 patients. The pulsotype identified had previously been isolated from another patient and from a tap water sample for 86 and 29 patients, respectively. The results differed according to the ICU. Exogenous acquisition of P.aeruginosa could be prevented in half of patients. The overall findings of this survey support the need for studies on routes of transmission and risk assessment approach to better define how to control exogenous acquisition in ICUs.

Tail Fiber Protein-Immobilized Magnetic Nanoparticle-Based Affinity Approaches for Detection of Acinetobacter baumannii.

Acinetobacter baumannii (A. baumannii) strains are common nosocomial pathogens that can cause infections and can easily become resistant to antibiotics. Thus, analytical methods that can be used to rapidly identify A. baumannii from complex samples should be developed. Tail fiber proteins derived from the tail fibers of bacteriophages can recognize specific bacterial surface polysaccharides. For example, recombinant tail proteins, such as TF2 and TF6 derived from the tail fibers of bacteriophages ϕAB2 and ϕAB6, can recognize A. baumannii clinical isolates M3237 and 54149, respectively. Thus, TF2 and TF6 can be used as probes to target specific A. baumannii strains. Generally, TF2 and TF6 are tagged with a hexahistidine (His6) for ease of purification. Given that His6 possesses specific affinity toward alumina through His6-Al chelation, TF2- and TF6-immobilized alumina-coated magnetic nanoparticles (Fe3O4@Al2O3 MNPs) were generated through chelation under microwave heating (power, 900 W) for 60 s in this study. The as-prepared TF2-Fe3O4@Al2O3 and TF6-Fe3O4@Al2O3 MNPs were used as affinity probes to trap trace A. baumannii M3237 and 54149, respectively, from sample solutions. Matrix-assisted laser desorption/ionization mass spectrometry capable of identifying bacteria on the basis of the obtained fingerprint mass spectra of intact bacteria was used as the detection tool. Results demonstrated that the current approach can be used to distinguish A. baumannii M3237 from A. baumannii 54149 by using TF2-Fe3O4@Al2O3 and TF6-Fe3O4@Al2O3 MNPs as affinity probes. Furthermore, the limits of detection of the current method for A. baumannii M3237 and 54149 are ∼105 and ∼104 cells mL-1, respectively. The feasibility of using the developed method to selectively detect A. baumannii M3237 and 54149 from complex serum samples was demonstrated.

Association between antimicrobial resistance among Enterobacteriaceae and burden of environmental bacteria in hospital acquired infections: analysis of clinical studies and national reports

BackgroundWHO has named three groups of gram-negative bacteria “our critical antimicrobial resistance-related problems globally”. It is thus a priority to unveil any important covariation of variables behind this three-headed epidemic, which has gained alarming proportions in Low Income Countries, and spreads rapidly. Environmental bacteria including Acinetobacter spp. are common nosocomial pathogens in institutions that have high rates of antimicrobial resistance among other groups of gram-negative bacteria. MethodsBased on two different data sources, we calculated the correlation coefficient (Pearson's r) between pathogenic burden of Acinetobacter spp. and antimicrobial resistance among Enterobacteriaceae in European and African nosocomial cohorts. Clinical reportsDatabase search for studies on nosocomial sepsis in Europe and Africa was followed by a PRISMA-guided selection process. National reportsData from Point prevalence survey of healthcare-associated infections published by European Centre for Disease Prevention and Control were used to study the correlation between prevalence of Acinetobacter spp. and antimicrobial resistance among K. pneumoniae in blood culture isolates. FindingsThe two approaches both revealed a strong association between prevalence of Acinetobacter spp. and rates of resistance against 3. generation cephalosporins among Enterobacteriaceae. In the study of clinical reports (13 selected studies included), r was 0.96 (0.80–0.99) when calculated by proportions on log scale. Based on national reports, r was 0.80 (0.56–0.92) for the correlation between resistance rates of K. pneumoniae and proportion of Acinetobacter spp. InterpretationThe critical antimicrobial resistance-related epidemics that concern enteric and environmental gram-negative bacteria are not independent epidemics; they have a common promoting factor, or they are mutually supportive. Further, accumulation of antimicrobial resistance in nosocomial settings depends on the therapeutic environment. Burden of Acinetobacter spp. as defined here is a candidate measure for this dependence.

Antibacterial and antibiofilm activity of acetone leaf extracts of nine under-investigated south African Eugenia and Syzygium (Myrtaceae) species and their selectivity indices

BackgroundAntimicrobial resistance (AMR) remains an important global health issue but the gap between AMR and development of new antimicrobials is increasing. Plant extracts may have good activity per se or may be sources of effective antimicrobial compounds which can act against planktonic and/or biofilms of pathogens. We determined the antimicrobial efficacy and cytotoxicity of some under-investigated plants from the Myrtaceae family endemic to South Africa. The ability of the plant extracts to inhibit or destroy pre-formed bacterial biofilms was also determined.MethodsBased on previous preliminary in vitro screening and on chemotaxonomy, nine species from the Myrtaceae family were selected. The antimicrobial activity of the crude acetone leaf extracts was determined against six common nosocomial pathogens, namely: Gram-positive bacteria (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium) using a two-fold serial microdilution assay with p-iodonitrotetrazolium violet as growth indicator. The number of antimicrobial compounds present in extracts was determined by bioautography. Cytotoxicity of extracts was determined against Vero kidney cells using a colorimetric tetrazolium-based assay. The total antibacterial activity (TAA) in ml/g and selectivity index (LC50/MIC) of the plant extracts were calculated. A modified crystal violet assay was used to determine the antibiofilm activity of the extracts.ResultsSyzygium legatii, Syzygium masukuense, and Syzygium species A had the best activities against Gram-negative and Gram-positive bacteria (MIC) values ranging from 0.04–0.08 mg/ml. Eugenia erythrophylla had the best MIC (0.02 mg/ml) against Bacillus cereus. Many extracts had relatively low cytotoxicity (LC50 > 20 μg/ml) leading to reasonable selectivity indices. Three leaf extracts (Syzygium masukuense, Syzygium species A, and Eugenia natalitia) were moderately cytotoxic (20 μg/ml < LC50 < 100 μg/ml). The plant extracts had a good capacity to reduce biofilm formation and good to poor potential to destroy pre-formed biofilms.ConclusionsThe plant species examined in this study had varying degrees of antibacterial activity against bacterial planktonic and biofilm forms with some having good activity against both forms. Several of these selected species may be potential candidates for further investigation to isolate antimicrobial compounds and to determine the mechanism of activity.

Comparative efficacy of doripenem versus meropenem for hospital-acquired and ventilator-associated pneumonia.

Doripenem shows good invitro activity against common nosocomial pathogens, such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii. However, the use of doripenem for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) remains controversial. The aim of this study was to compare the efficacy and safety between doripenem and meropenem for patients with HAP or VAP. Adult patients diagnosed with HAP and VAP at National Taiwan University Hospital, who received doripenem or meropenem for more than 48h between January 2015 and November 2017, were retrospectively reviewed. All-cause mortality on the 30th day was used as the primary outcome measurements. Fifty-seven patients with doripenem and 252 patients with meropenem were analyzed. Compared to the meropenem group, the doripenem group was younger and had a higher Sequential Organ Failure Assessment (SOFA) score. Multivariable Cox regression analysis revealed that presence of solid organ malignancies (adjusted hazard ratio [AHR], 1.82; 95% CI, 1.04-3.19, p=0.003) and SOFA score (AHR, 1.10; 95% CI, 1.03-1.17, p=0.003) were independent factors associated with mortality. There was no survival difference of 30-day mortality between patients receiving doripenem and meropenem for HAP or VAP (log-rank p=0.113). However, a poorer outcome was observed among patients with hematological disease in the doripenem group (log-rank p=0.012). Our results demonstrate that doripenem has similar efficacy as meropenem in HAP or VAP patients. With an aim to enhance antibiotic diversity, doripenem could be an alternative choice for patients with HAP or VAP, except for those with hematological malignancies.

MRSA in Pigs and the Environment as a Risk for Employees in Pig-Dense Areas of Sri Lanka

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is widely spread in intensive farming systems and considered an occupational risk for humans. MRSA is a common nosocomial pathogen in Sri Lanka, but information about prevalence of MRSA in pig farming in Sri Lanka is scarce. Farming is largely a small-scale confined system, and antimicrobial use in these systems is poorly regulated with no veterinary oversight for use. This study identified on 100 pig farms a MRSA prevalence of 10%, with MRSA-positive samples in pigs, farm workers, and dust of 1.2% (6/493), 2.2% (5/228), and 0.8% (1/119), respectively. The genotypes of these strains were compared with 22 human MRSA strains from a hospital; identified in pig farms were CC1/ST1/t127, CC5/ST5/t002, CC6/ST6/t304, or t4403, singleton ST3841/t10744, of which CC1/ST1/t127 and CC/ST5/t002 were present both in isolates from pigs and humans, suggesting a human origin. LA-MRSA types associated with intensive farming (ST398, ST9) were not detected. The low MRSA prevalence at farm level (10% vs. up to 70% in intensive farming systems) might be due to the management of these farms—open air and low dust. We conclude that in Sri Lanka the occupational risk for MRSA acquisition of people working with pigs in the described management systems is negligible.

Occurrence of VIM-4 metallo-β-lactamase-producing Pseudomonas aeruginosa in an Algerian hospital.

Pseudomonas aeruginosa is one of the most common nosocomial pathogens, known with a wide resistance to antimicrobials. Carbapenemases producing Pseudomonas aeruginosa is a growing global public health concern as this pathogen is easily transmissible among patients. Metallo-Beta-lactamases is the most important class of these carbapenemases with their broad-spectrum resistance profile. This study was conducted to investigate the prevalence of MBL-producing P. aeruginosa collected in an Algerian hospital. All Metallo-β-lactamase (MBL)-producing P. aeruginosa isolates recovered from patients during a 2 years period (2015-2016) were studied using a combination of phenotypic and molecular typing methods (susceptibility testing, molecular characterization of carbapenemase-encoding genes, multi-locus sequence typing and pulsed-field gel electrophoresis). A total of twenty-six MBL producing P. aeruginosa of 188 isolates were investigated. The burns unit ranked in the first position of the majority of identified cases with 73.07%. About 73.07% of total MBL isolates were mainly isolated from pus samples. The studied isolates were subjected to the molecular typing, in which 4 different Dra1-PFGE patterns and 3 sequences type were assigned (ST244, ST381, and ST1076), and all isolates were revealed positive for VIM-4. We report the third description of blaVIM-4 in Algeria indicating the emergence and spread of carbapenemase-encoding genes among P. aeruginosa in the hospital environment.

Changing trend of microbiologic profile and antibiotic susceptibility of the microorganisms isolated in the neonatal nosocomial sepsis: a 14 years analysis

Objective: Neonatal sepsis, especially nosocomial sepsis (NS) is one of the main causes of mortality and morbidity in neonates. Our aim was to investigate microorganisms responsible for NS and antimicrobial susceptibility patterns and to compare them in a different period.Methods: Blood culture registers from the Microbiology Laboratory were reviewed for the study population. The neonates with proven NS were enrolled in the study. Microorganisms responsible for NS and antimicrobial susceptibility patterns were recordedResults: The incidence of Gram-positive, Gram-negative, and fungal microorganisms were 61.6% (n = 570), 27.1% (n = 251) and 11.3% (n = 104), respectively. The most common isolated Gram-positive, Gram-negative pathogens and fungi were Coagulase-negative staphylococci (CoNS), Klebsiella pneumoniae, and C. guilliermondii. There was an increasing resistance rate among common nosocomial pathogens especially oxacillin resistant CoNS strains and increasing rate for extended-spectrum beta-lactamase (ESBL) positive microorganisms. Low susceptibility was detected to commonly used antibiotics for empirical treatment in neonatal sepsis.Conclusions: Our result showed that multiresistant microorganisms, especially oxacillin-resistant staphylococci and gram-negative bacilli resistant to cephalosporin have an increasing rate. Every unit should evaluate the causative agents and antimicrobial susceptibilities in order to select an appropriate regime for nosocomial sepsis. Periodic surveillance of organisms and their antibiotic resistance patterns in every unit might help physicians for proper selection of antibiotics for treatment of neonatal NS.

Multiple Benefits of Plasmid-Mediated Quinolone Resistance Determinants in Klebsiella pneumoniae ST11 High-Risk Clone and Recently Emerging ST307 Clone.

International high-risk clones of Klebsiella pneumoniae are among the most common nosocomial pathogens. Increased diversity of plasmid-encoded antimicrobial resistance genes facilitates spread of these clones causing significant therapeutic difficulties. The purpose of our study was to investigate fluoroquinolone resistance in extended-spectrum beta-lactamase (ESBL)-producing strains, including four K. pneumoniae and a single K. oxytoca, isolated from blood cultures in Hungary. Whole-genome sequencing and molecular typing including multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were performed in selected strains. Gene expression of plasmid-mediated quinolone resistance determinants (PMQR) was investigated by quantitative-PCR. MLST revealed that three K. pneumoniae strains belonged to ST11 and one to ST307 whereas K. oxytoca belonged to ST52. The isolates harbored different β-lactamase genes, however, all K. pneumoniae uniformly carried blaCTX-M-15. The K. pneumoniae isolates exhibited resistance to fluoroquinolones and carried various PMQR genes namely, two ST11 strains harbored qnrB4, the ST307 strain harbored qnrB1 and all K. pneumoniae harbored oqxAB efflux pump. Levofloxacin and moxifloxacin MIC values of K. pneumoniae ST11 and ST307 clones correlated with qnr and oqxAB expression levels. The qnrA1 carrying K. oxytoca ST52 exhibited reduced susceptibility to fluoroquinolones. The maintained expression of qnr genes in parallel with chromosomal mutations indicate an additional protective role of Qnr proteins that can support dissemination of high-risk clones. During development of high-level fluoroquinolone resistance, high-risk clones retain fitness thus, enabling them for dissemination in hospital environment. Based on our knowledge this is the first report of ST307 clone in Hungary, that is emerging as a potential high-risk clone worldwide. High-level fluoroquinolone resistance in parallel with upregulated PMQR gene expression are linked to high-risk K. pneumoniae clones.

Antibiotic sensitivity pattern of bacteria isolated from Nigerian currencies (Naira) circulating in some hospitals of Kano metropolis, Kano state, Nigeria

Microbial contamination of fomites such as currency notes is of public health concern as contaminated materials might act as vehicle for the transmission of pathogenic and drug resistant organisms. The aim of this study was to evaluate antibiotic susceptibility profile of bacteria isolated from Nigerian currencies circulating in some hospitals of Kano metropolis. Four hundred paper currency notes of all denominations obtained from three hospitals (Hasiya Bayero pediatrics hospital, Murtala Mohammad specialist hospital and Aminu Kano Teaching Hospital) and school environment (Bayero university Kano) were investigated. The samples were all screened for bacterial pathogens and some common nosocomial pathogens using standard microbiological procedures. Antibiotic susceptibility testing was done using disc diffusion method to detect the presence of resistant isolates including multidrug resistant organisms (MDR) and methicillin resistant Staphylococcus aureus (MRSA). The results of the study revealed that 84.7% of currencies were contaminated with pathogenic organisms. Bacteria isolated from currencies circulating in hospital were more resistant to antibiotics than non hospital source isolates (p&lt; 0.05). The prevalence of MDR was found to be (16% and 6% p&lt; 0.005) and (6.8% and 5.9% p&gt;0.05) for MRSA from hospital and non hospital currencies respectively. Staphylococcus aureus, S. epidermidis, Escherichia coli, Bacillus species, Streptococcus species, Proteus species, Klebsiella spp, Salmonella spp and Pseudomonas aeruginosa were the most frequent isolated bacteria. Ampicillin, cotrimoxaxole, and amoxicillin/clavulanate showed high levels of inactivity. Ciprofloxacin had the greatest activity (40% to 100%) against the isolates. The study revealed that Currency notes circulating in hospital are highly contaminated with potentially pathogenic bacteria including drug resistant nosocomial pathogens, MRSA and MDR organisms. Measures should therefore be employed to ensure the safety of currency handlers in the hospital.Key words: Antibiotic, Sensitivity pattern, Bacteria, Nigerian Currencies, Hospitals

Multidrug-Resistant Enterobacter cloacae Complex Emerging as a Global, Diversifying Threat.

The Enterobacter cloacae complex (ECC) includes common nosocomial pathogens capable of producing a wide variety of infections. Broad-spectrum antibiotic resistance, including the recent emergence of resistance to last-resort carbapenems, has led to increased interest in this group of organisms and carbapenem-resistant E. cloacae complex (CREC) in particular. Molecular typing methods based on heat-shock protein sequence, pulsed-field gel electrophoresis, comparative genomic hybridization, and, most recently, multilocus sequence typing have led to the identification of over 1069 ECC sequence types in 18 phylogenetic clusters across the globe. Whole-genome sequencing and comparative genomics, moreover, have facilitated global analyses of clonal composition of ECC and specifically of CREC. Epidemiological and genomic studies have revealed diverse multidrug-resistant ECC clones including several potential epidemic lineages. Together with intrinsic β-lactam resistance, members of the ECC exhibit a unique ability to acquire genes encoding resistance to multiple classes of antibiotics, including a variety of carbapenemase genes. In this review, we address recent advances in the molecular epidemiology of multidrug-resistant E. cloacae complex, focusing on the global expansion of CREC.

Nosocomial Pathogens: An In-Depth Analysis of the Vectorial Potential of Cockroaches.

Nosocomial or healthcare-associated infections are regarded as the most frequent adverse event that threatens patients’ safety and has serious economic and social consequences. Cockroach infestation is common in many hospitals, especially in the developing world. Common nosocomial pathogens isolated from cockroaches include Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae. Cockroaches also harbor epidemiologically significant antibiotic-resistant organisms, such as carbapenem-resistant Enterobacteriaceae, which complicate nosocomial infections. Therefore, cockroaches constitute an important vector for nosocomial pathogens, and there should be zero tolerance for their presence in healthcare facilities. This paper aims to elucidate the possible role of cockroaches in nosocomial infections by reviewing the relevant research publications.

Predominance of ST22-MRSA-IV Clone and Emergence of Clones for Methicillin-Resistant &lt;i&gt;Staphylococcus aureus&lt;/i&gt; Clinical Isolates Collected from a Tertiary Teaching Hospital Over a Two-Year Period

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens, causing mild to severe infections. This study aimed to determine the genotypic and phenotypic characteristics of clinical MRSA isolates collected from a teaching hospital from 2014 - 2015. These isolates were genotyped by multilocus sequence typing, staphylococcal cassette chromosomal mec (SCCmec) typing, virulence genes detection, and pulsed-field gel electrophoresis; they were phenotyped based on their antibiotics susceptibility profiles. The most prevalent sequence type was ST22. ST3547 was identified from a blood isolate from 2015. Three SCCmec types (III in 26.26%, IV in 70.71%, and V in 3.03% isolates) were detected. Agr type I, II, and III were also detected among the isolates. The most prevalent virulence genes found were hemolysin (100%) and intracellular adhesion (91.9%). At least one staphylococcal enterotoxin was detected in 83 (83.8%) isolates. All the isolates were susceptible to vancomycin (minimum inhibitory concentration ≤ 2 μg/mL). Statistical analysis revealed a significant increase in hypertension (p = 0.035), dyslipidemia and obesity (p = 0.046), and previous exposure to any quinolone (p = 0.010) cases over the two-year period. The emergence and circulation of community-associated MRSA variants were observed in our hospital.

One-year molecular surveillance of carbapenem-susceptible A. baumannii on a German intensive care unit: diversity or clonality

BackgroundA. baumannii is a common nosocomial pathogen known for its high transmission potential. A high rate of carbapenem-susceptible Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB)-complex in clinical specimens led to the implementation of a pathogen-based surveillance on a 32-bed surgical intensive care unit (SICU) in a German tertiary care centre.MethodsBetween April 2017 and March 2018, ACB-complex isolates with an epidemiological link to the SICU were further assessed. Identification to the species level was carried out using a multiplex PCR targeting the gyrB gene, followed by RAPD, PFGE (ApaI) and whole genome sequencing (WGS, core genome MLST, SeqSphere+ software, Ridom). Additional infection prevention and control (IPC) measures were introduced as follows: epidemiological investigations, hand hygiene training, additional terminal cleaning and disinfection incl. UV-light, screening for carbapenem-susceptible A. baumannii and environmental sampling. Hospital-acquired infections were classified according to the CDC definitions.ResultsFourty four patients were colonized/infected with one or two (different) carbapenem-susceptible ACB-complex isolates. Fourty three out of 48 isolates were classified as hospital-acquired (detection on or after 3rd day of admission). Nearly all isolates were identified as A. baumannii, only four as A. pittii. Twelve patients developed A. baumannii infections. Genotyping revealed two pulsotype clusters, which were confirmed to be cgMLST clonal cluster type 1770 (n = 8 patients) and type 1769 (n = 12 patients) by WGS. All other isolates were distinct from each other. Nearly all transmission events of the two clonal clusters were confirmed by conventional epidemiology. Transmissions stopped after a period of several months. Environmental sampling revealed a relevant dissemination of A. baumannii, but only a few isolates corresponded to clinical strains. Introduction of the additional screening revealed a significantly earlier detection of carbapenem-susceptible A. baumannii during hospitalization.ConclusionsA molecular and infection surveillance of ACB-complex based on identification to the species level, classic epidemiology and genotyping revealed simultaneously occurring independent transmission events and clusters of hospital-acquired A. baumannii. This underlines the importance of such an extensive surveillance methodology in IPC programmes also for carbapenem-susceptible A. baumannii.

Antibiotic activity of the antioxidant drink effective Microorganism-X (EM-X) extracts against common nosocomial pathogens: an in vitro study

EM-X is a mixed consortium of beneficial microorganisms of natural occurrence (lactic bacteria, yeast and photosynthetic bacteria). The aim of this study is to evaluate the antimicrobial activity in-vitro of EM-X to the principal pathogens isolated in clinical settings and to understand if it could be a suitable adjuvant to synthetic antibiotics. According the World Health Organization we performed antimicrobial assays to the main pathogens usually found in hospital wards. After antimicrobial testing, EM-X has been shown to be most effective at a concentration of 40 mg/ml four time concentrated than the commercial original solution (10 mg/ml). The EM-X antimicrobial action, although effective against bacteria, has proved to be ineffective against the candida genus. This active range of concentration (mg/ml) may prove a very weak action of EM, but further investigations will be done to separate the active substances form the inactive ones in this complex mixture.

Development and evaluation of loop-mediated isothermal amplification assay for the rapid detection of Escherichia coli and its microbial toxin

Objective To establish and optimize a loop-mediated isothermal amplification (LAMP) method for the rapid detection of Escherichia coli and its microbial toxin. Methods The LAMP reaction system and reaction conditions were determined by optimizing LAMP reaction, and the optimized LAMP system was used for the detection. Results Primers targeting shiga toxin (stx) gene and O157 antigen gene rfbe were designed. The established and optimized LAMP amplification system contained 1.2 mmol/L dNTPs, 10 mmol/L MgSO4, 0.4 mol/L betaine, 1 μl 10×Bst DNA polymerase Buffer, 8 U Bst DNA polymerase fragment, 2 μl DNA template, and the ratio of inner-primer (FIP and BIP) and outer-primer (F3 and B3) were 8∶1. Time and temperature for LAMP was 60 min, 60 ℃. The sensitivity was 103 times higher than polymerase chain reaction (PCR), reached 5×101 CFU/ml. When LAMP was applied to 19 reference strains, 102 EHEC strains, the specification was 100% while identification rate of rfbe, stx1 and stx2 gene reached 100%, 95.2%, 92.9%. Conclusions The LAMP method showed a promising prospect for the rapid detection of common nosocomial pathogens microbial toxin. Key words: Enterohemorrhagic escherichia coli/MI; Nucleic acid amplification techniques; Shiga toxin/GE; Bacterial proteins/GE

Multidrug-Resistant Pseudomonas Infections: Hard to Treat, But Hope on the Horizon?

As the sixth most common nosocomial pathogen in the USA, Pseudomonas aeruginosa poses a significant threat to patients within the healthcare system. Its intrinsic and acquired resistance mechanisms also significantly limit the choices for antimicrobial therapy, prompting an increase in the research and development of antibacterial agents with enhanced activity against multidrug-resistant (MDR) P. aeruginosa. While many approved and pipeline antibiotics have activity against wild-type P. aeruginosa, only four new antibiotics have promising activity against MDR P. aeruginosa: ceftazidime-avibactam (Avycaz®), ceftolozane-tazobactam (Zerbaxa®), cefiderocol, and imipenem-cilastatin/relebactam. The goal of this paper is to review the epidemiology and mechanisms of resistance in P. aeruginosa as well as explore the newly approved and pipeline agents that overcome these mechanisms of resistance. Ceftazidime-avibactam and ceftolozane-tazobactam are currently FDA-approved and available for use, while cefiderocol and imipenem-cilastatin/relebactam are in development. Current evidence suggests ceftazidime-avibactam and ceftolozane-tazobactam both may have a role in treatment of MDR P. aeruginosa infections. Ceftolozane-tazobactam appears to be modestly more potent against P. aeruginosa, but emergence of resistance has been noted in various reported cases. Trials are ongoing for cefiderocol and imipenem-cilastatin/relebactam and early results appear promising. The aforementioned agents fill important gaps in the antibiotic armamentarium, particularly for patients with MDR P. aeruginosa infections who otherwise have extremely limited and often toxic antibiotic options. However, resistance to all of these agents will likely emerge, and additional antibiotic development is warranted to provide sufficient options to successfully manage MDR P. aeruginosa infections.