Catalytic specificity and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa

The escalating drug resistance among microorganisms underscores the urgent need for innovative therapeutic strategies and a comprehensive understanding of bacteria's defense mechanisms against oxidative stress and antibiotics. Among the recently discovered barriers, the endogenous production of hydrogen sulfide (H2S) via the reverse transsulfuration pathway, emerges as a noteworthy factor. In this study, we have explored the catalytic capabilities and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa (PaCGL), a multidrug-opportunistic pathogen chiefly responsible for nosocomial infections. In addition to a canonical L-cystathionine hydrolysis, PaCGL efficiently catalyzes the production of H2S using L-cysteine and/or L-homocysteine as alternative substrates. Comparative analysis with the human enzyme and counterparts from other pathogens revealed distinct structural features within the primary enzyme cavities. Specifically, a distinctly folded entrance loop could potentially modulate the access of substrates and/or inhibitors to the catalytic site. Our findings offer significant insights into the structural evolution of CGL enzymes across different pathogens and provide novel opportunities for developing specific inhibitors targeting PaCGL.

Antimicrobial and anti-biofilm efficacy of different inorganic and organic zinc forms against multidrug-resistant Escherichia, Klebsiella, Staphylococcus and Pseudomonas

In our study antibacterial and anti-biofilm efficacy of 2 inorganics (Zn(II) sulphate monohydrate; Zn(II) sulphate heptahydrate) and 3 organic Zn(II) substances (Zn(II) chelate of protein hydrolysate: Zn-Bio; Zn(II) chelate of amino acid hydrate: Zn-AMK; Zn(II) chelate of glycine hydrate: Zn-Gly) were explored and compared against multidrug resistant Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Klebsiella oxytoca (K. oxytoca) and Pseudomonas aeruginosa (P. aeruginosa) using by the 96- wells microtiter plate-based resazurin and/or crystal violet assay. Our finding confirmed that Zn(II)-sulphates and Zn(II)-amino acid complexes exhibit dose and genus-based antibacterial and anti-biofilm potential. Organic compounds (Zn-AMK and Zn-Gly) were more effective against bacterial growth, except P. aeruginosa. Besides Zn-AMK, others organic and inorganic forms of Zn(II) caused predominantly statistically significant decrease of biofilm production in all of tested bacteria. Current data highlights that Zn(II) in various forms has a great potential to be developed as antibacterial and anti-biofilm agents.

Antibacterial applications of biologically synthesized Pichia pastoris silver nanoparticles

Objectives

This article highlights the biological synthesis of silver nanoparticles (AgNPs) with their characteristic analysis, and it focuses on the application of synthesized NPs against multidrug resistance (MDR) bacteria. A cytotoxicity study was performed to assess the biocompatibility.

Methods

Silver nanoparticle (AgNPs) formation was confirmed by different characterization methods such as UV-Vis spectrophotometer, Dynamic light scattering (DLS)- Zeta, Fourier transform infrared (FTIR), and Transmission electron microscope (TEM). The antimicrobial activity of the AgNPs was checked against various bacterial strains of Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Enterococcus faecalis (E. faecalis), and Klebsiella pneumonia (K. pneumonia) by disc diffusion, minimum inhibition concentration test (MIC), and kinetic studies. The cytotoxicity of NPs against the Vero cell line was studied by cytotoxic assay.

Results

The primary analysis of the formation of nanoparticles (NPs) was made by UV-Vis spectrophotometric analysis at 400 nm. At the same time, the efficient capping checked by FTIR shows the presence of a functional group at different wavelengths 3284, 1641,1573,1388,1288, and 1068 cm-1. At the same time, the transmission electron microscopic analysis (TEM) and DLS show that the shape and size of the synthesized NPs possess an average size of around ∼10-30 nm with spherical morphology. Further, the zeta potential confirmed the stability of the NPs. While the yield of NPs formation from silver salt was determined by an online yield calculator with the EDX analysis results. Synthesized NPs showed bactericidal effects against all the selected MDR pathogens with nontoxic effects against mammalian cells.

Conclusion

Our findings indicate the remarkable antimicrobial activity of the biologically synthesized AgNPs, which can be an antimicrobial agent against multi-drug-resistant bacteria.

Furan-based Chalcone Annihilates the Multi-Drug-Resistant Pseudomonas aeruginosa and Protects Zebra Fish Against its Infection

The emergence of carbapenem-resistant Pseudomonas aeruginosa, a multi-drug-resistant bacteria, is becoming a serious public health concern. This bacterium infects immunocompromised patients and has a high fatality rate. Both naturally and synthetically produced chalcones are known to have a wide array of biological activities. The antibacterial properties of synthetically produced chalcone were studied against P. aeruginosa. In vitro, study of the compound (chalcone derivative named DKO1), also known as (2E)-1-(5-methylfuran-2-yl)-3-(4-nitrophenyl) prop-2-en-1-one, had substantial antibacterial and biofilm disruptive action. DKO1 effectively shielded against P. aeruginosa-induced inflammation, oxidative stress, lipid peroxidation, and apoptosis in zebrafish larvae. In adult zebrafish, the treatment enhanced the chances of survivability and reduced the sickness-like behaviors. Gene expression, biochemical analysis, and histopathology studies found that proinflammatory cytokines (TNF-α, IL-1β, IL-6, iNOS) were down regulated; antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) levels increased, and histoarchitecture was restored in zebrafish. The data indicate that DKO1 is an effective antibacterial agent against P. aeruginosa demonstrated both in vitro and in vivo.

Microbiological profile of multidrug resistant bacteria before and during COVID-19 in CHU Mohammed VI

Background and Objectives

A new type of corona virus has caused Corona virus disease-19 and, subsequently, a global pandemic. All individuals are prone to the disease, so drastic measures were taken to prevent its spread. This study aimed to evaluate the impact of COVID-19 on the progression of the antimicrobial resistance rate by comparing two periods: before and during COVID-19.

Materials and Methods

We used a cross-sectional design to investigate the Antimicrobial Resistance (AMR) rate before (03/2019 to 03/2020) and during COVID-19 (03/2020 to 03/2021) in a University Hospital in Marrakech. The data were analyzed using SPSS Version 25.0.

Results

Among the 7106 specimens, there was a significant increase in the multidrug-resistant bacterial from 27.38% to 35.87% during COVID-19 (p<0.001), particularly in blood culture, cerebrospinal fluid, catheter, and pus. However, there was a non-significant change in puncture fluid, expectoration, protected distal sampling, joint fluid, stool culture, and genital sampling. A decrease in Multidrug-resistant bacteria (MDRB) was observed only in cytobacteriological urine tests (p<0.05). According to species, there was an increase in extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and methicillin-resistant Staphylococcus aureus.

Conclusion

In our study, it is particularly noticeable that the MDRB has increased. These results highlight the importance that the pandemic has not been able to slow the progression.

Does PTCY increase the risk of infections?

PTCY has been mainly used in haploidentical transplant (haploHSCT), but its use in matched donors allowed better evaluation of infectious risk conferred separately by PTCY or donor type. PTCY increased the risk of bacterial infections, both in haploidentical and matched donors, mainly pre-engraftment bacteremias. Bacterial infections, particularly due to multidrug-resistant Gram-negatives, were main causes of infection-related deaths. Higher rates of CMV and other viral infections were reported, mainly in haploHSCT. The role of donor might be more important than the role of PTCY. PTCY increased the risk of BK virus associated hemorrhagic cystitis, and seemed associated with higher risk of respiratory viral infections. Fungal infections were frequent in haploHSCT PCTY cohorts without mold active prophylaxis, but the exact role of PTCY needs to be established. Infections appear to be increased in patients receiving PTCY, although the exact role of GvHD prophylaxis and donor type can only be assessed in prospective trials.

Chorioamnionitis and maternal sepsis caused by AmpC β-lactamase-producing Escherichia coli infection: A case report

INTRODUCTION

Multidrug resistant bacteria have increasingly become a concern regarding infection treatment. The clinical course of chorioamnionitis (CAM) caused by multidrug-resistant bacteria is not well understood.

PRESENTATION OF CASE

We report a case of CAM caused by AmpC-type β-lactamase (AmpC)-producing Escherichia coli (E. coli), a multidrug-resistant bacterium. A 35-year-old primipara was hospitalized with preterm membrane rupture at 36 weeks of gestation and was started on oral ampicillin. On the fourth day after admission, the patient was diagnosed with CAM owing to high fever development and uterine tenderness; therefore, an emergency cesarean section was performed. AmpC-producing E. coli were detected in blood and amniotic fluid cultures. Post-operation, the patient received treatment for septic shock and was discharged on the 15th post-operative day.

DISCUSSION

The patient initially had no symptoms of infection but later experienced fever and uterine pain. She underwent an emergency cesarean section, and both mother and baby were successfully treated with broad-spectrum antibiotics. CAM associated with multidrug-resistant bacteria is more challenging to manage compared to infections in other parts of the body, as it occurs in unique environments such as the uterus, during pregnancy, and in the presence of compromised immunity.

CONCLUSION

The development of new diagnostic criteria and effective biomarkers is needed to improve early detection, and adherence to standard precautions can help prevent the acquisition of multidrug-resistant bacteria in healthcare settings.

COVID-19 associated infections in the ICU setting: A retrospective analysis in a tertiary-care hospital

INTRODUCTION

Our work describes the frequency of superinfections in COVID-19 ICU patients and identifies risk factors for its appearance. Second, we evaluated ICU length of stay, in-hospital mortality and analyzed a subgroup of multidrug-resistant microorganisms (MDROs) infections.

METHODS

Retrospective study conducted between March and June 2020. Superinfections were defined as appeared ≥48h. Bacterial and fungal infections were included, and sources were ventilator-associated lower respiratory tract infection (VA-LRTI), primary bloodstream infection (BSI), secondary BSI, and urinary tract infection (UTI). We performed a univariate analysis and a multivariate analysis of the risk factors.

RESULTS

Two-hundred thirteen patients were included. We documented 174 episodes in 95 (44.6%) patients: 78 VA-LRTI, 66 primary BSI, 9 secondary BSI and 21 UTI. MDROs caused 29.3% of the episodes. The median time from admission to the first episode was 18 days and was longer in MDROs than in non-MDROs (28 vs. 16 days, p<0.01). In multivariate analysis use of corticosteroids (OR 4.9, 95% CI 1.4-16.9, p 0.01), tocilizumab (OR 2.4, 95% CI 1.1-5.9, p 0.03) and broad-spectrum antibiotics within first 7 days of admission (OR 2.5, 95% CI 1.2-5.1, p<0.01) were associated with superinfections. Patients with superinfections presented respect to controls prolonged ICU stay (35 vs. 12 days, p<0.01) but not higher in-hospital mortality (45.3% vs. 39.7%, p 0.13).

CONCLUSIONS

Superinfections in ICU patients are frequent in late course of admission. Corticosteroids, tocilizumab, and previous broad-spectrum antibiotics are identified as risk factors for its development.

Synthesis of AgNPs from leaf extract of Naringi crenulata and evaluation of its antibacterial activity against multidrug resistant bacteria

The biosynthesis of AgNPs using a methanolic extract of Naringi crenulata is described in this study. UV-visible spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), particle size analyzer (PSA), scanning electron microscope (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) were used to characterize the synthesized AgNPs. The UV-visible spectrum revealed a sharp peak at 420 nm, which represents silver's strong Plasmon resonance. FTIR and XRD confirmed the functional groups (N-H stretch, alkanes, O-H stretch, carboxylic acid, N-H bend, C-X fluoride, and C-N stretch) and face-centered cubic crystalline structure of synthesized AgNPs. SEM and TEM analyses revealed that the synthesized nanoparticles had a spherical morphology with an average diameter of 32.75 nm. The synthesized AgNPs have antibacterial activity against multidrug-resistant bacteria pathogens such as Vibrio cholerae, Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Klebsiella pneumoniae. AgNPs can be synthesized using a methanolic extract of Naringi crenulate, and the resulting particle may have wide range of biological applications.

Deciphering longitudinal optical-density measurements to guide clinical dosing regimen design: A model-based approach

BACKGROUND

Model-based analysis of longitudinal optical density measurements from a bacterial suspension exposed to antibiotics has been proposed as a potentially efficient and effective method for extracting useful information to improve the individualized design of treatments for bacterial infections. To that end, the authors developed in previous work a mathematical modeling framework that can use such measurements for design of effective dosing regimens.

OBJECTIVES

Here we further explore ways to extract information from longitudinal optical density measurements to predict bactericidal efficacy of clinically relevant antibiotic exposures.

METHODS

Longitudinal optical density measurements were collected in an automated instrument where Acinetobacter baumannii, ATCC BAA747, was exposed to ceftazidime concentrations of 1, 4, 16, 64, and 256 mg/L and to ceftazidime/amikacin concentrations of 1/0.5, 4/2, 16/8, 64/32, and 256/128 (mg/L)/(mg/L) over 20 h. Calibrated conversion of measurements produced total (both live and dead) bacterial cell concentration data (CFU/mL equivalent) over time. Model-based data analysis predicted the bactericidal efficacy of ceftazidime and of ceftazidime/amikacin (at ratio 2:1) for periodic injection every 8 h and subsequent exponential decline with half-life of 2.5 h. Predictions were experimentally tested in an in vitro hollow-fiber infection model, using peak concentrations of 60 and 150 mg/L for injected ceftazidime and of 40/20 (mg/L)/(mg/L) for injected ceftazidime/amikacin.

RESULTS

Model-based analysis predicted low (<62%) confidence in clinically relevant suppression of the bacterial population by periodic injections of ceftazidime alone, even at high peak concentrations. Conversely, analysis predicted high (>95%) confidence in bacterial suppression by periodic injections of ceftazidime/amikacin combinations at a wide range of peak concentrations ratioed at 2:1. Both predictions were experimentally confirmed in an in vitro hollow fiber infection model, where ceftazidime was periodically injected at peak concentrations 60 and 150 mg/L (with predicted suppression confidence 38% and 59%, respectively) and a combination of ceftazidime/amikacin was periodically injected at peak concentrations 40/20 (mg/L)/(mg/L) (with predicted suppression confidence 98%).

CONCLUSIONS

The paper highlights the potential of clinicians using the proposed mathematical framework to determine the utility of different antibiotics to suppress a patient-specific isolate. Additional studies will be needed to consolidate and expand the utility of the proposed method.

Silver nanoparticle synthesis and their potency against multidrug-resistant bacteria: a green approach from tissue-cultured Coleus forskohlii

Drug resistance is a major concern nowadays, and finding alternatives of the well-known antibiotic is necessary. Green nanoparticles are emerging as a tenable alternative to this with a large spectrum of activity. The present manuscript describes an eco-friendly approach for green synthesis of silver nanoparticles from both in vitro and in vivo leaf extract of Coleus forskohlii. Leaf extracts were used in synthesis of nanoparticles which were further analyzed through UV-Vis, dynamic light scattering, energy-dispersive spectroscopy, and transmission electron microscopy. Antimicrobial activity of silver nanoparticles alone, as well as crude extract of the plant itself, was carried out against eight multidrug-resistant respiratory tract infecting pathogenic strains. Satisfactory antimicrobial activities were found with nanoparticles, in vitro and in vivo leaf extracts. However, gradually higher to lower inhibition potential against pathogenic bacterial strains was found in silver nanoparticles, in vitro and in vivo leaf extracts. Seven bioactive compounds were detected in the crude extract through gas chromatography-mass spectroscopy analysis. Results revealed that nanoparticle formation occurred in a wide range of sizes (10-50 nm) and shapes (trigonal, hexagonal, spherical, rod). The diversity in size and shape of the nanoparticles makes them biologically active. Silver nanoparticle exhibits significantly better antimicrobial activities as compared to the plant extract in case of nearly all pathogens with a maximum zone of inhibition of 15.33 ± 0.94 mm where more than 12 well-known antibiotics failed to respond. Because of this broad-spectrum activity of nanoparticles as well as the leaf extracts against life-threatening microbes, it can be used as future generation drugs.

Impact of the COVID-19 pandemic on the incidence of multidrug-resistant bacterial infections in an acute care hospital in Brazil

BACKGROUND

The impact of COVID-19 on healthcare- associated infections (HCAI) caused by multidrug-resistant (MDR) bacteria that contribute to higher mortality is a growing area of study METHODS: This retrospective observational study compares the incidence density (ID) of HCAI caused by MDR bacteria (CRE, CRAB, CRP, MRSA and VRE) pre-COVID (2017-2019) and during the COVID-19 pandemic (2020) in overall hospitalized patients and in intensive care (ICU) units.

RESULTS

We identified 8,869 HCAI, of which 2,641 (29.7%) were caused by bacterial MDR, and 1,257 (14.1%) were from ICUs. The overall ID of MDR infections increased 23% (P < .005) during COVID-19. The overall per-pathogen analysis shows significant increases in infections by CRAB and MRSA (+108.1%, p<0.005; +94.7%, p<0.005, respectively), but not in CRE, CRP, or VRE. In the ICU, the overall ID of MDR infections decreased during COVID, but that decline was not significant (-6.5%, P = .26). The ICU per-pathogen analysis of ID of infection showed significant increases in CRAB and MRSA (+42.0%, P = .001; +46.2%, P = .04), significant decreases in CRE and CRP (-26.4%, P = .002; -44.2%, P = 0.003, respectively) and no change in VRE.

CONCLUSIONS

The COVID-19 pandemic correlates to an increase in ID of CRAB and MRSA both in ICU and non-ICU setting, and a decrease in ID of CRE and CRP in the ICU setting. Infection control teams should be aware of possible outbreaks of CRAB and MRSA and promote rigorous adherence to infection control measures as practices change to accommodate changes in healthcare needs during and after the pandemic.

COVID-19 associated infections in the ICU setting: A retrospective analysis in a tertiary-care hospital

Introduction

Our work describes the frequency of superinfections in COVID-19 ICU patients and identifies risk factors for its appearance. Second, we evaluated ICU length of stay, in-hospital mortality and analyzed a subgroup of multidrug-resistant microorganisms (MDROs) infections.

Methods

Retrospective study conducted between March and June 2020. Superinfections were defined as appeared ≥48 h. Bacterial and fungal infections were included, and sources were ventilator-associated lower respiratory tract infection (VA-LRTI), primary bloodstream infection (BSI), secondary BSI, and urinary tract infection (UTI). We performed a univariate analysis and a multivariate analysis of the risk factors.

Results

Two-hundred thirteen patients were included. We documented 174 episodes in 95 (44.6%) patients: 78 VA-LRTI, 66 primary BSI, 9 secondary BSI and 21 UTI. MDROs caused 29.3% of the episodes. The median time from admission to the first episode was 18 days and was longer in MDROs than in non-MDROs (28 vs. 16 days, p < 0.01). In multivariate analysis use of corticosteroids (OR 4.9, 95% CI 1.4–16.9, p 0.01), tocilizumab (OR 2.4, 95% CI 1.1–5.9, p 0.03) and broad-spectrum antibiotics within first 7 days of admission (OR 2.5, 95% CI 1.2–5.1, p < 0.01) were associated with superinfections. Patients with superinfections presented respect to controls prolonged ICU stay (35 vs. 12 days, p < 0.01) but not higher in-hospital mortality (45.3% vs. 39.7%, p 0.13).

Conclusions

Superinfections in ICU patients are frequent in late course of admission. Corticosteroids, tocilizumab, and previous broad-spectrum antibiotics are identified as risk factors for its development.

High burden of multidrug resistant bacteria detected in Little Akaki River

Spread of antimicrobial-resistant bacteria between humans and animals occurs when the environment is contaminated with animal and human wastes. A total of 30 samples were collected from the Akaki river to identify antimicrobial-resistant bacteria. Bacterial enumeration and characterization was done by spreading serially diluted water samples on MacConkey agar. Sixty four bacterial isolates were identified and susceptibility tested using VITEK 2. The most frequently identified bacteria were Providencia alcalifaciens 10 (15.6%), Kluyvera cryocrescens 9 (14.1%) and Citrobacter freundii 7(10.9%), respectively. Multiple drug resistant bacteria were identified, constituting 17 (28%) of the 64 identified isolates. Multiple antimicrobial resistance (MAR) index of the six sites laid in the range 0.13-0.27, being the highest score located downstream of all the sampling sites. Species MAR index varied from 0.12 to 0.40. Out of 64 isolates, 54 (84.4%) of them were resistant to Ampicillin. On the contrary, most of the isolates were sensitive to Amikacin and meropenem. In conclusion, our findings indicated E.coli count was above the WHO permissible levels. The predominant isolates were P. alcalifaciens, and C. freundii. The MAR index of major isolates was greater than two, implying the study sites were exposed to high-risk sources of human or animal contamination.

Trends in the proportion of resistant bacteria involved in ventilator-associated pneumonia as the first hospital-acquired infection in intensive care units between 2003 and 2016 in Lyon, France

The aim of this study was to describe the proportion of multidrug-resistant microorganisms (MDROs) involved in ventilator-associated pneumonia (VAP) as the first hospital-acquired infection in 536 adults with restricted risk factors for MDRO-related infection. We found a significant decrease in the percentage of MDROs involved in VAP between 2003 and 2016 and this percentage increased when VAP occurred after day 10.

Antibiotic resistance in microbes: History, mechanisms, therapeutic strategies and future prospects

Antibiotics have been used to cure bacterial infections for more than 70 years, and these low-molecular-weight bioactive agents have also been used for a variety of other medicinal applications. In the battle against microbes, antibiotics have certainly been a blessing to human civilization by saving millions of lives. Globally, infections caused by multidrug-resistant (MDR) bacteria are on the rise. Antibiotics are being used to combat diversified bacterial infections. Synthetic biology techniques, in combination with molecular, functional genomic, and metagenomic studies of bacteria, plants, and even marine invertebrates are aimed at unlocking the world's natural products faster than previous methods of antibiotic discovery. There are currently only few viable remedies, potential preventive techniques, and a limited number of antibiotics, thereby necessitating the discovery of innovative medicinal approaches and antimicrobial therapies. MDR is also facilitated by biofilms, which makes infection control more complex. In this review, we have spotlighted comprehensively various aspects of antibiotics viz. overview of antibiotics era, mode of actions of antibiotics, development and mechanisms of antibiotic resistance in bacteria, and future strategies to fight the emerging antimicrobial resistant threat.

Disinfectant resistance in bacteria: Mechanisms, spread, and resolution strategies

Disinfectants are widely acknowledged for removing microorganisms from the surface of the objects and transmission media. However, the emergence of disinfectant resistance has become a severe threat to the safety of life and health and the rational allocation of resources due to the reduced disinfectant effectiveness. The horizontal gene transfer (HGT) of disinfectant resistance genes has also expanded the resistant flora, making the situation worse. This review focused on the resistance mechanisms of disinfectant resistant bacteria on biofilms, cell membrane permeability, efflux pumps, degradable enzymes, and disinfectant targets. Efflux can be the fastest and most effective resistance mechanism for bacteria to respond to stress. The qac genes, located on some plasmids which can transmit resistance through conjugative transfer, are the most commonly reported in the study of disinfectant resistance genes. Whether the qac genes can be transferred through transformation or transduction is still unclear. Studying the factors affecting the resistance of bacteria to disinfectants can find breakthrough methods to more adequately deal with the problem of reduced disinfectant effectiveness. It has been confirmed that the interaction of probiotics and bacteria or the addition of 4-oxazolidinone can inhibit the formation of biofilms. Chemicals such as eugenol and indole derivatives can increase bacterial sensitivity by reducing the expression of efflux pumps. The role of these findings in anti-disinfectant resistance has proved invaluable.

Biogenic Fabrication, Characterization and Drug Loaded Antimicrobial Assay of Silver Nanoparticles Using Centratherum anthalminticum (L.) Kuntze

Bionanotechnology is considered a safe and ecofriendly route for the biosynthesis of metal nanoparticles from plant extracts, microorganisms, and biomaterials. The present study was focused on the fabrication of silver nanoparticles (<50 nm) biogenically from the novel Centratherum anthelmminticum's aqueous seed extract. The obtained nanoproduct was evaluated by X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM), UV-Visible spectroscopy, FTIR and Raman spectroscopy. The particle size and surface charge were estimated by Dynamic light scattering (DLS) and Zeta potential measurements. The nanoparticles showed cubic close packed (ccp) morphology with miller indices (111), (200), (220), (311) and (222). The λ_max for synthesized silver nanoparticles was measured in the range of 436 nm, 464 nm and 467 nm for 1 mM, 5 mM and 10 mM samples, respectively. The bioreduction of silver ions exhibited a gradual color change which confirms the formation of silver nanoparticles under UV-visible spectrum. Ag-O and Ag-N stretching vibrations corresponding to the bond formation between silver and oxygen of the carboxylate group and nitrogen of amine was corroborated by the presence of a sharp peak in Raman spectra at 245 cm^-1. Antimicrobial activity was assessed against eight bacterial and three fungal strains. The silver nanoparticles fabricated from 10 mM AgNO₃ solution showed significant results against all Gram-negative bacteria, with the further restriction in growth of C. albicans and A. niger. From in-vitro antimicrobial assay, it was observed that drug-loaded silver nanoparticles (Ciprofloxacin +10 mM) displayed a stronger potential than the synthesized silver nanoparticles and ciprofloxacin alone to restrain the development of E. coli, and E. aerogenes.

Bacteria drug resistance profile affects knee and hip periprosthetic joint infection outcome with debridement, antibiotics and implant retention

Background

Evaluate the effect of bacteria drug resistance profile on the success rates of debridement, antibiotics and implant retention.

Methods

All early acute periprosthetic infections in hip and knee arthroplasties treated with DAIR at our institution over the period from 2011 to 2015 were retrospectively analyzed. The success rate was evaluated according to the type of organism identified in culture: multidrug-sensitive (MSB), methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Gram-negative bacteria (MRB) and according to other risk factors for treatment failure. The data were analyzed using univariate and multivariate statistics.

Results

Fifty-seven patients were analyzed; there were 37 in the multidrug-sensitive bacteria (MSB) group, 11 in the methicillin-resistant Staphylococcus aureus (MRSA) group and 9 in the other multidrug-resistant Gram-negative bacteria (MRB) group. There was a statistically significant difference (p < 0.05) in the treatment failure rate among the three groups: 8.3% for the MSB group, 18.2% for the MRSA group and 55.6% for the MRB group (p = 0.005). Among the other risk factors for treatment failure, the presence of inflammatory arthritis presented a failure rate of 45.1 (p < 0.05).

Conclusion

DAIR showed a good success rate in cases of early acute infection by multidrug-sensitive bacteria. In the presence of infection by multidrug-resistant bacteria or association with rheumatic diseases the treatment failure rate was higher and other surgical options should be considered in this specific population. The MRSA group showed intermediate results between MSB and MRB and should be carefully evaluated.

Co-occurrence of a novel VIM-1 and FosA3-encoding multidrug-resistant plasmid and a KPC-2-encoding pKP048-like plasmid in a clinical isolate of Klebsiella pneumoniae sequence type 11

The spread of carbapenem-resistant Enterobacteriaceae (CRE) worldwide remains a major threat to public health. Notably, carbapenemase-encoding genes are usually located in plasmids harboring other resistance determinants, and isolates having multiple plasmids are often highly resistant to carbapenems. In this study, we characterized the genetic context of coproduction of KPC-2, VIM-1, and FosA3 via two plasmids in the multidrug-resistant Klebsiella pneumoniae sequence type 11 (ST11) isolate JS187, recovered during an outbreak of KPC-2-producing K. pneumoniae in a Chinese teaching hospital in 2008. Plasmid p187-1, coharboring bla_VIM-1 and fosA3, consisted of a pKOX-R1-like backbone and two multidrug resistant (MDR) regions separated by pKHS1-like backbone sequences involving plasmid replication and stability. The MDR region 1 was a chimera composed of the bla_VIM-1-bearing In916-like integron and Tn1721-like transposon, and was disrupted by sequential insertion of an IS26-based transposition unit carrying bla_CTX-M-3 and a ΔTn3-like transposon bearing bla_TEM-1. MDR region 2 was an IS26-array structure with fosA3 and bla_SHV-12. Plasmid p187-2 harboring bla_KPC-2 was closely related to pKP048. bla_KPC-2 in p187-2 was carried by a Tn1721 variant, which differed from the prototype Tn1721-bla_KPC-2 transposon observed in pKP048 by disruption of an IS26 at Tn3 and deletion of a 31-kb MDR fragment. Co-existence of the novel VIM-1- and FosA3-encoding MDR plasmid p187-1 and the KPC-2-encoding pKP048-like plasmid p187-2 made K. pneumoniae JS187 highly resistant to carbapenems. Moreover, p187-1 still carried genes conferring resistance to cephalosporins, fosfomycin, chloramphenicol, and quaternary ammonium, posing substantial challenges for the treatment of Enterobacteriaceae infections. Thus, monitoring the prevalence and evolution of these plasmids and/or strains is critical.

Association of sputum microbiome with clinical outcome of initial antibiotic treatment in hospitalized patients with acute exacerbations of COPD

Identification of risk factors for antibiotic treatment failure is urgently needed in acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Here we investigated the relationship between sputum microbiome and clinical outcome of choice of initial antibiotics during hospitalization of AECOPD patients. Sputum samples of 41 AECOPD patients and 26 healthy controls were collected from Guangzhou Medical University, China. Samples were processed for 16S rRNA gene-based microbiome profiling. Thirty patients recovered with initial antibiotic treatment (antibiotic success or AS), while 11 patients showed poor outcome (antibiotic failure or AF). Substantial differences in microbiome were observed in AF versus AS patients and healthy controls. There was significantly decreased alpha diversity and increased relative abundances of Pseudomonas, Achromobacter, Stenotrophomonas and Ralstonia in AF patients. Conversely, Prevotella, Peptostreptococcus, Leptotrichia and Selenomonas were depleted. The prevalence of Selenomonas was markedly reduced in AF versus AS patients (9.1 % versus 60.0 %, P = 0.004). The AF patients with similar microbiome profiles in general responded well to the same new antibiotics in the adjusted therapy, indicating sputum microbiome may help guide the adjustment of antibiotics. Random forest analysis identified five microbiome operational taxonomic units together with C-reactive protein, procalcitonin and blood neutrophil count showing best predictability for antibiotic treatment outcome (area under curve 0.885). Functional inference revealed an enrichment of microbial genes in xenobiotic metabolism and antimicrobial resistance in AF patients, whereas genes in DNA repair and amino acid metabolism were depleted. Sputum microbiome may determine the clinical outcome of initial antibiotic treatment and be considered in the risk management of antibiotics in AECOPD.

Synthesis of biosurfactant stabilized silver nanoparticles, characterization and their potential application for bactericidal purposes

Uniformly dispersed silver nanoparticles (AgNPs) with remarkable colloidal stability were synthesised using chemical reduction method in lipopeptide biosurfactant reverse micelles. Transmission Electron microscopy (TEM), Scanning electron microscopy (SEM) and UV-vis spectroscopy analysis exhibited monodisperse nanoparticles with spherical morphology of diameter of 21 ± 2. The lipopeptide stabilized AgNPs displayed remarkable antibacterial activity with minimum inhibitory concentration (MIC) value of 15.625 μg/mL against Gram-negative Pseudomonas aeruginosa CB1 and Gram-positive Bacillus subtilis CN2 strains with a significant dose-dependent reduction of cell viability and loss of membrane integrity. Investigation of AgNPs internalization and dissolution assays demonstrated 42-fold higher leaching of the lipopeptide-stabilized AgNPs compared to the bare AgNPs, and concentration dependent increase in cellular uptake with subsequent damage to intracellular organelles. Further ultrastructural observation using TEM revealed internalization and strong binding of considerable amount of AgNPs on the lipopolysaccharide layer of the Gram-negative and peptidoglycans layer of Gram-positive bacteria indiscriminately, demonstrating robust antibacterial activity and potential application to treat multidrug resistant bacteria.

Management of infections in patients with cirrhosis in the context of increasing therapeutic resistance: A systematic review

Patients with cirrhosis are prone to develop bacterial infections, which consist in one of the major precursors of Acute-on-Chronic Liver Failure (ACLF) and are responsible for a high mortality rate. In recent years, the management of bacterial infections in patients with cirrhosis has become increasingly complicated due to a change in bacterial ecology associated with a higher rate of cocci gram positive bacteria in Europe and America along with the emergence of a multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacteria leading to a decrease in the efficacy of empirical strategies based on the administration of third-generation cephalosporins. MDR and XDR now account for about 40% of the infections worldwide, and up to 70% in India. Among them, the most common ones are extended-spectrum beta-lactamase producing (ESBL-P) bacteria, carbapenem-resistant enterobacteriaceae (CRE), Methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE). An early diagnosis associated to an empirical antibiotic adapted to the site of infection and potential bacterial resistance is now crucial in order to improve the chances of survival and contain the resistance phenomenon. Moreover, a fungal infection must always be discussed in these high-risks patients, especially in the absence of clinical improvement under appropriate antibiotic treatment. In this review, we will focus on the emerging threat of MDR and XDR organisms, as well as fungal infections, in order to better adapt the therapeutic management of cirrhotic patients with infections.

Bacteremia in critical care units at Bugando Medical Centre, Mwanza, Tanzania: the role of colonization and contaminated cots and mothers' hands in cross-transmission of multidrug resistant Gram-negative bacteria

Background

Multidrug resistance (MDR) is a major clinical problem in tertiary hospitals in Tanzania and jeopardizes the life of neonates in critical care units (CCUs). To better understand methods for prevention of MDR infections, this study aimed to determine, among other factors, the role of MDR-Gram-negative bacteria (GNB) contaminating neonatal cots and hands of mothers as possible role in transmission of bacteremia at Bugando Medical Centre (BMC), Mwanza, Tanzania.

Methods

This cross-sectional, hospital-based study was conducted among neonates and their mothers in a neonatal intensive care unit and a neonatology unit at BMC from December 2018 to April 2019. Blood specimens (n = 200) were sub-cultured on 5% sheep blood agar (SBA) and MacConkey agar (MCA) plates. Other specimens (200 neonatal rectal swabs, 200 maternal hand swabs and 200 neonatal cot swabs) were directly inoculated on MCA plates supplemented with 2 μg/ml cefotaxime (MCA-C) for screening of GNB resistant to third generation cephalosporins, r-3GCs. Conventional biochemical tests, Kirby-Bauer technique and resistance to cefoxitin 30 μg were used for identification of bacteria, antibiotic susceptibility testing and detection of MDR-GNB and screening of potential Amp-C beta lactamase producing GNB, respectively.

Results

The prevalence of culture confirmed bacteremia was 34.5% of which 85.5% were GNB. Fifty-five (93.2%) of GNB isolated from neonatal blood specimens were r-3GCs. On the other hand; 43% of neonates were colonized with GNB r-3GCs, 32% of cots were contaminated with GNB r-3GCs and 18.5% of hands of neonates’ mothers were contaminated with GNB r-3GCs. The prevalences of MDR-GNB isolated from blood culture and GNB r-3GCs isolated from neonatal colonization, cots and mothers’ hands were 96.6, 100, 100 and 94.6%, respectively. Significantly, cyanosis (OR[95%CI]: 3.13[1.51–6.51], p = 0.002), jaundice (OR[95%CI]: 2.10[1.07–4.14], p = 0.031), number of invasive devices (OR[95%CI]: 2.52[1.08–5.85], p = 0.031) and contaminated cot (OR[95%CI]: 2.39[1.26–4.55], p = 0.008) were associated with bacteremia due to GNB. Use of tap water only (OR[95%CI]: 2.12[0.88–5.09], p = 0.040) was protective for bacteremia due to GNB.

Conclusion

High prevalence of MDR-GNB bacteremia and intestinal colonization, and MDR-GNB contaminating cots and mothers’ hands was observed. Improved cots decontamination strategies is crucial to limit the spread of MDR-GNB. Further, clinical presentations and water use should be considered in administration of empirical therapy whilst awaiting culture results.

Comprehensive investigation on the synergistic antibacterial activities of Jatropha curcas pressed cake and seed oil in combination with antibiotics

Synergistic combinations of various antimicrobial agents are considered ideal strategies in combating clinical and multidrug resistant (MDR) infections. In this study, antibacterial potential of Jatropha curcas crude seed extracts, seed oil, commercially available antibiotics, and their combinations were investigated for their synergistic effect against clinical, MDR and ATCC bacterial strains by agar well diffusion assay. Methanolic extracts remained more active against Staphylococcus aureus (ATCC), with zone of inhibition (ZOI) of 21 mm, than clinical and methicillin-resistant S. aureus (MRSA) strains (ZOI range ~ 15.0-17.0 mm). Molecular docking demonstrated that beta-monolaurin from methanolic extract exhibited greater affinity conformation for UDP-N-acetylmuramoyl-tripeptide-D-alanyl-D-alanine (MurF) ligase's active pocket with binding energy of -7.3 kcal/mol. Moxifloxacin exhibited greater activity against Escherichia coli (ATCC) (ZOI ~ 50.0 mm), followed by ofloxacin against Pseudomonas chlororaphis (47.3 mm), moxifloxacin against P. monteilii (47 mm), P. aeruginosa (46.3 mm) and MRSA2 (46 mm) and ofloxacin against S. aureus (ATCC) strains (45.7 mm). Methanolic extract in combination with rifampicin showed the highest synergism against MRSA strains, A. baumannii, E. coli, E. faecalis, S. aureus, and P. aeruginosa, A. baumannii (MDR strain), P. chlororaphis, E. coli ATCC25922 and S. aureus ATCC25923. In combinations, moxifloxacin exhibited the highest antagonism. The methanolic, n-hexane, aqueous extracts and seed oil in various combinations with antibiotics showed 44.71, 32.94, 9.41 and 25.88% synergism, respectively. The current study showed that potency of antibiotics was improved when screened in combination with J. curcas seed's components, supporting the drug combination strategy to combat antibacterial resistance.

Photo-inactivation and efflux pump inhibition of methicillin resistant Staphylococcus aureus using thiolated cobalt doped ZnO nanoparticles

Multidrug resistance (MDR) in bacteria is a major concern these days. One of the reasons is the mutation in efflux pump that prevents the retention of antibiotics and drugs in the bacterial cell. The current work is a step to overcome MDR in bacteria via inhibition of efflux pump and further photoinhibition by thiolated chitosan coated cobalt doped zinc oxide nanoparticles (Co-ZnO) in visible light. Co-ZnO were synthesized in a size range of 40-60 nm. Antibacterial activity of the Co-ZnO against methicillin resistant Staphylococcus aureus (MRSA) was found 100% at a concentration of 10 μg/ml upon activation in sunlight for 15 min. Interestingly, it was found that cobalt as a dopant was able to increase the photodynamic and photothermal activity of Co-ZnO, as in dark conditions, there was only 3-5% of inhibition at 10 μg/ml of nanoparticle concentration. Upon excitation in light, these nanoparticles were able to generate reactive oxygen species (ROS) with a quantum yield of 0.23 ± 0.034. The nanoparticles were also generating heat, Because of the magnetic nature, thus helping in more killing. Thiolated chitosan further helped in blocking the efflux pump of MRSA. The current nanoparticles were also found biocompatible on human red blood cells (LD₅₀ = 214 μg/ml). These data suggest that the MRSA killing ability was facilitated through efflux inhibition and oxidative stress upon excitation in visible light hence, were in accordance with previous findings.

Biosynthesis of Ag and Cu NPs by secondary metabolites of usnic acid and thymol with biological macromolecules aggregation and antibacterial activities against multi drug resistant (MDR) bacteria

Thymol and usnic acid as the important secondary metabolites of respectively Artemisia haussknechtii and Protoparmeliopsis muralis were used for reduction and stabilizing of AgNO₃ and CuSO₄ in metal nanoparticles (MNPs) biosynthesis process. Antibacterial effects of prepared Ag-thymol (ATNPs), Ag-usnic acid (AUNPs), Cu-thymol (CTNPs), and Cu-usnic acid (CUNPs) on multi drug resistant (MDR) bacteria including methicillin-resistant Staphylococcus aureus (MRSA) (gram positive), Acinetobacter baumannii (A52), and Klebsiella pneumonia (K38) (gram negative) were compared with thymol, usnic acid, AgNO₃, CuSO₄, and tetracycline. Results of this study showed higher antibacterial activities of usnic acid, CUNPs, and CTNPs with MIC/MBC values (20, 40, and 40 μg/mL, respectively) than ATNPs and AUNPs against MRSA bacteria. Leakage of macromolecules involving nucleic acids and proteins from bacteria under stress of MNPs, thymol, and usnic acid proved significant antibacterial activities of usnic acid, and Cu NPs. In addition, SEM images illustrated different patterns of aggregation in biofilms resulted from interactions of these antibacterial agents with bacterial macromolecules. Totally, this investigation illustrated new green method of Ag and Cu NPs biosynthesis with suitable antibacterial properties.

Trimethoprim-sulfamethoxazole vs. colistin or ampicillin-sulbactam for the treatment of carbapenem-resistant Acinetobacter baumannii: A retrospective matched cohort study

OBJECTIVES

This study aimed to assess the effectiveness of trimethoprim-sulfamethoxazole (TMP/SMX) as monotherapy for the treatment of carbapenem-resistant Acinobacter baumannii (A. baumannii) (CRAB) infections.

METHODS

This retrospective cohort study included patients receiving TMP/SMX as the main treatment for severe infections caused by CRAB, who were matched with patients treated with colistin or ampicillin-sulbactam (AMP/SUL) by age, Charlson score, department, and source of infection. Outcomes were compared among all patients and in a subgroup of propensity-score (PS) matched patients. The PS matching was performed using a match tolerance of 0.15 with replacement.

RESULTS

Fifty-three patients treated with TMP/SMX and 83 matched patients treated with colistin or AMP/SUL were included. Variables that were independently significantly associated with TMP/SMX treatment included admission for infection and septic shock, while abnormal cognition on admission and intensive care unit admission were associated with colistin or AMP/SUL treatment. All-cause 30-day mortality was lower with TMP/SMX compared with the comparator antibiotics among all patients (24.5%, 13 of 53 vs. 38.6%, 32 of 83, P=0.09) and in the PS-matched subgroup (29%, 9 of 31 vs. 55.2% 16 of 29, P=0.04). Treatment failure rates were not significantly different overall (34%, 18 of 53 vs. 42.4%, 35 of 83, P=0.339) and in the PS-matched subgroup (35.5%, 11 of 31 vs. 44.8%, 13 of 29, P=0.46). Time to clinical stability and hospitalization duration were significantly shorter with TMP/SMX. Patients treated with TMP/SMX probably had less severe infections than those treated with other antibiotics, even after matching.

CONCLUSIONS

TMP/SMX might be a valuable treatment option for TMP/SMX-susceptible CRAB infections. Given the very limited available treatment options, further studies assessing its effectiveness and safety are necessary.

Isolation by Miniaturized Culture Chip of an Antarctic bacterium Aequorivita sp. with antimicrobial and anthelmintic activity

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Novel microbial isolation approach allowed the identification of a Gram-negative Antarctic bacterium belonging to the genus Aequorivita.

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Aequorivita sp. showed antimicrobial and anthelmintic activity without toxic effect towards eukaryotic cells.

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The whole genome of Aequorivita sp. was sequenced and compared with other strains to identify biosynthetic gene clusters.

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This novel approach represents a promising strategy to isolate rare or novel strains useful for biotechnological applications.

Microbes are prolific sources of bioactive molecules; however, the cultivability issue has severely hampered access to microbial diversity. Novel secondary metabolites from as-yet-unknown or atypical microorganisms from extreme environments have realistic potential to lead to new drugs with benefits for human health. Here, we used a novel approach that mimics the natural environment by using a Miniaturized Culture Chip allowing the isolation of several bacterial strains from Antarctic shallow water sediments under near natural conditions. A Gram-negative Antarctic bacterium belonging to the genus Aequorivita was subjected to further analyses. The Aequorivita sp. genome was sequenced and a bioinformatic approach was applied to identify biosynthetic gene clusters. The extract of the Aequorivita sp. showed antimicrobial and anthelmintic activity towards Multidrug resistant bacteria and the nematode Caenorhabditis elegans. This is the first multi-approach study exploring the genomics and biotechnological potential of the genus Aequorivita that is a promising candidate for pharmaceutical applications.

Outcome of co-infection with opportunistic and multidrug resistant Aeromonas hydrophila and A. veronii in zebrafish: Identification, characterization, pathogenicity and immune responses

Fish can be potentially co-infected by two or more bacterial strains, which can make synergistic influence on the virulence of infection. In this study, two opportunistic and multidrug resistant Aeromonas strains were isolated from wounds of morbid zebrafish with typical deep skin lesions similar to Motile Aeromonas Septicemia. Isolates were genetically identified as A. hydrophila and A. veronii by 16 S rRNA sequencing and phylogenetic analysis. Both isolates were positive for virulent genes (aerA, lip, ser, exu gcaT) and selected phenotypic tests (DNase, protease, gelatinase, lipase, biofilm production and β-haemolysis). A. hydrophila and A. veronii had strong antibiotic resistance against ampicillin, tetracycline, nalidixic acid, kanamycin, erythromycin, clindamycin and trimethoprim-sulfamethoxazole. Histopathological studies revealed that co-infection causes severe necrosis and hypertrophy in the muscles, kidney and liver of zebrafish. Naturally co-infected zebrafish showed highly induced tnf-α, il-1β, il-6, il-12, ifn, ifn-γ, cxcl18 b and ccl34a.4 at transcription level compared to healthy fish, suggesting virulence factors may activate immune and inflammatory responses of zebrafish. Experimentally infected zebrafish showed significantly higher mortality under co-infection with A. hydrohila and A. veronii (87%), followed by individual challenge of A. hydrophila (72%) or A. veronii (67%) suggesting that virulence of A. hydrophila have greater pathogenicity than A. veronii during co-infection.

Biosynthesis and comparative bactericidal activity of silver nanoparticles synthesized by Aspergillus flavus and Penicillium crustosum against the multidrug-resistant bacteria

Bacterial resistance to antibiotics has been emerged as a major health problem in the recent years. Silver nanoparticles (AgNPs) have been known to have an inhibitory effect to the bacterial growth, however, the strength of this antibacterial activity in correlation with the physical properties of these AgNPs has barely studied. Thus, in the present study, the biosynthetic potency of AgNPs from different fungal isolates as well as their antibacterial activity towards multidrug resistant bacteria, have been assessed. Aspergillus flavus and Penicillium crustosum have been selected for their higher reducing potency of silver ions (Ag+) into silver nanoparticles with strong physical stability, as revealed from UV, DLS and TEM analyses. The synthesized AgNPs by A. flavus have molecular size ranged from 5-10 nm with maximum UV-absorbance at λ384 nm, while that of P. crustosum was ranged from 30-40 nm and UV-absorbance at λ420 nm. The size and shape of AgNPs resolved from Zeta sizer, have been authenticated from the TEM analysis, having spherical to oval shape. The anti-bacterial activity of AgNPs was checked against the selected multi-drug resistant bacteria, Staphylococcus aureus and Escherichia coli. AgNPs from both fungal sources had an inhibitory effect for these bacteria isolates, however, AgNPs from A. flavus with molecular diameter 5 nm had a significant antibacterial effect "about 1.5 folds" higher than AgNPs of P. crustosum (size 35 nm). The MIC of A. flavus AgNPs was 0.42 and 0.41 µg/ml towards S. aureus and E. coli, while, the MIC of P. crustosum AgNPs was 0.86 µg/ml and 0.65 µg/ml, respectively. The bactericidal potency of AgNPs is strongly correlated to their molecular size. Thus, using of AgNPs (~5 nm)as solely antibacterial agent or in combination with commercial antibiotics to increase their potency and to reduce their overdosing and overusing, could be a novel platform for controlling the multi-drug resistance pathogenic bacteria.

Action mechanism of melittin-derived antimicrobial peptides, MDP1 and MDP2, de novo designed against multidrug resistant bacteria

The emergence and dissemination of multidrug resistant (MDR) bacteria are major challenges for antimicrobial chemotherapy of bacterial infections. In this critical condition, cationic antimicrobial peptides are 'novel' promising candidate antibiotics to overcome the issue. In this study, we investigated the antibacterial mechanism of new melittin-derived peptides (i.e., MDP1 and MDP2) against multidrug resistant Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. MDP1 was designed with deletion of three amino acid residues, i.e., S₁₈, W₁₉, and I₂₀, from the end of second hydrophobic motif of melittin. In the next step, VLTTG in MDP1 sequence was substituted with tryptophan residue. MDP1 and MDP2 had a high-antibacterial activity against MDR and reference strains of S. aureus, E. coli, and P. aeruginosa. DNA and calcein release and flow cytometry assays indicate a time-dependent antibacterial activity on the examined bacteria affected by both MDP1 and MDP2. Finally, SEM analyses highlighted dose- and time-dependent effects of MDP1 and MDP2 on S. aureus and E. coli bacteria by induction of vesicle or pore formation as well as cell lysis. In this study we successfully showed that rational truncation of large hydrophobic motifs can lead to significant reduction in toxicity against human RBCs and improving the antibacterial activity as well. Analyses of data from DNA release, fluorometry, flow cytometry, and morphological assays demonstrated that the MDP1 and MDP2 altered the integrity of both Gram-positive and Gram-negative bacterial membranes and killed the bacteria via membrane damages.

Tigecycline in the treatment of multidrug-resistant Acinetobacter baumannii meningitis: Results of the Ege study

OBJECTIVES

In this study we retrospectively reviewed A. baumannii meningitis cases treated with tigecycline including regimens and evaluated the efficacy of tigecycline in the therapy.

PATIENTS AND METHODS

Study was performed in seven tertiary-care educational hospitals from five cities of Turkey and one center from France. We extracted data and outcomes of all adult (aged >18) patients with culture proven A. baumannii meningitis treated with tigecycline including antibiotic therapy until April 2016.

RESULTS

A total of 23 patients (15 male and eight female) fulfilled our inclusion criteria. All Acinetobacter strains were carbapenem-resistant and susceptible to tigecycline. Six cases received tigecycline monotherapy while 17 received tigecycline including combination therapy (10 with colistin, 4 with netilmicin, 3 with amikacin, 4 with meropenem). Seven of 23 cases (30%) died during the tigecycline including therapy (1 in monotherapy, 4 in colistin, 2 in netilmicin, 1 amikacin, one case received tigecycline + netilmicin followed by tigecycline + colistin). Hence, overall end of treatment (EOT) success was 70%. However, since further 27% died due to additional nosocomial infections, overall clinical success (relieved symptoms at the EOT and one-month post-therapy survival without any relapse or reinfection) decreased to 43%.

CONCLUSION

We conclude that tigecycline may be an alternative in the salvage treatment of nosocomial multidrug-resistant Acinetobacter spp. meningitis. Acinetobacter spp. Meningitis.

Bloodstream infections in cancer patients. Risk factors associated with mortality

OBJECTIVE

The aim of this study was to evaluate the clinical characteristics and risk factors associated with mortality in cancer patients with bloodstream infections (BSI), analyzing multidrug resistant bacteria (MDR).

METHODS

We conducted a prospective observational study at a cancer referral center from August 2016 to July 2017, which included all BSI.

RESULTS

4220 patients were tested with blood cultures; 496 were included. Mean age was 48 years. In 299 patients with solid tumors, secondary BSI and Central Line-Associated BSI (CLABSI) were the most common (55.9% and 31.8%, respectively). In 197 hematologic patients, primary and mucosal barrier injury (MBI) BSI were the main type (38.6%). Gram-negative were the most frequent bacteria (72.8%), with Escherichia coli occupying the first place (n=210, 42.3%), 48% were Extended-Spectrum Beta-Lactamase (ESBL) producers, and 1.8% were resistant to carbapenems. Mortality at day 30, was 22%, but reached 70% when patients did not receive an appropriate antimicrobial treatment. Multivariate analysis showed that progression or relapse of the oncologic disease, inappropriate antimicrobial treatment, and having resistant bacteria were independently associated with 30-day mortality.

CONCLUSIONS

Emergence of MDR bacteria is an important healthcare problem worldwide. Patients with BSI, particularly those patients with MDR bacteria have a higher mortality risk.

Incidence of risk factors for bloodstream infections in patients with major burns receiving intensive care: A retrospective single-center cohort study

OBJECTIVES

The objective was primarily to identify risk factors for bloodstream infections (BSI) caused by different pathogens.

METHODS

A retrospective single-center cohort study was performed on 472 burn patients with an abbreviated burn severity index (ABSI)≥3, a total burn surface area (TBSA)≥10%, and an ICU stay of at least 24h. Risk factors for different BSI pathogens were analyzed by competing risks regression model of Fine and Gray.

RESULTS

A total of 114 burn patients developed 171 episodes of BSIs caused by gram-negative bacteria (n=78;46%), gram-positive bacteria (n=69;40%), and fungi (n=24;14%) median after 14days (range, 1-164), 16days (range, 1-170), and 16days (range, 0-89), respectively. A total of 24/114 patients (21%) had fatal outcomes. Isolation of the most common bloodstream isolates Enterococcus sp. (n=26), followed by Candida sp. and Pseudomonas sp. (n=22 for both) was significantly associated with increased TBSA (p≤0.006) and ABSI (p<0.0001) and need for fasciotomy (p<0.01). The death risk of patients with MDR gram-negative bacteremia was significantly increased by a hazard ratio of 12.6 (95% CI:4.8-32.8; p<0.0001).

CONCLUSIONS

A greater TBSA and ABSI were associated with a significantly higher incidence of BSIs caused by Pseudomonas sp., Enterococcus sp. and Candida sp.

Nosocomial spontaneous bacterial peritonitis antibiotic treatment in the era of multi-drug resistance pathogens: A systematic review

AIM

To systematically review literature upon aetiology of nosocomial spontaneous bacterial peritonitis (N-SBP) given the rising importance of multidrug-resistant (MDR) bacteria.

METHODS

A literature search was performed on MEDLINE and Google Scholar databases from 2000 to 15th of November 2016, using the following search strategy: "spontaneous" AND "peritonitis".

RESULTS

The initial search through electronic databases retrieved 2556 records. After removing duplicates, 1958 records remained. One thousand seven hundred and thirty-five of them were excluded on the basis of the screening of titles and abstract, and the ensuing number of remaining articles was 223. Of these records, after careful evaluation, only 9 were included in the qualitative analysis. The overall proportion of MDR bacteria turned out to be from 22% to 73% of cases across the studies.

CONCLUSION

N-SBP is caused, in a remarkable proportion, by MDR pathogens. This should prompt a careful re-assessment of guidelines addressing the treatment of this clinical entity.

Emergence of drug resistant bacteria at the Hajj: A systematic review

BACKGROUND

Hajj is the annual mass gathering of Muslims, and is a reservoir and potential source of bacterial transmission. The emergence of bacterial transmission, including multi-drug resistance (MDR) bacteria, during Hajj has not been systematically assessed.

METHODS

Articles in Pubmed, Scopus, and Google scholar were identified using controlled words relating to antibiotic resistance (AR) at the Hajj from January 2002 to January 2017. Eligible studies were identified by two researchers. AR patterns of bacteria were obtained for each study.

RESULTS

We included 31 publications involving pilgrims, Hajj workers or local patients attending hospitals in Mecca, Mina, and the Medina area. Most of these publications provided antibiotic susceptibility results. Ten of them used the PCR approach to identify AR genes. MRSA carriage was reported in pilgrims and food handlers at a rate of 20%. Low rates of vancomycin-resistant gram-positive bacteria were reported in pilgrims and patients. The prevalence of third-generation cephalosporin-resistant bacteria was common in the Hajj region. Across all studies, carbapenem-resistant bacteria were detected in fewer than 10% of E.coli isolates tested but up to 100% in K. pneumoniae and A. baumannii. Colistin-resistant Salmonella enterica, including mcr-1 colistin-resistant E.coli and K.pneumoniae were only detected in the pilgrim cohorts.

CONCLUSION

This study provides an overview of the prevalence of MDR bacteria at the Hajj. Pilgrims are at high risk of AR bacterial transmission and may carry and transfer these bacteria when returning to their home countries. Thus, pilgrims should be instructed by health care practitioners about hygiene practices aiming at reducing traveler's diarrhea and limited use of antibiotics during travel in order to reduce the risk of MDR bacterial transmission.

Evaluation of antibacterial activity of the bark and leaf extracts of Brosimum gaudichaudii Trécul against multidrug resistant strains

Brosimum gaudichaudii Trécul., a plant that belongs to Moraceae family, is found throughout the Brazilian Cerrado. The antimicrobial activities of ethanolic bark and leaf extracts of B. gaudichaudii were tested against multiresistant bacteria isolated from diabetic foot infections (DFIs). Antimicrobial activity of the extracts was evaluated by agar disc diffusion (DD) and broth dilution (BD) methods. By BD method, bark (53.85, 45.83%) and leaf (42.31, 50.00%) extracts contained antimicrobial activity against both gram-negative and gram-positive bacteria. Increased antimicrobial activity was observed when bark and leaf extracts were tested against Staphylococcus aureus (63.64%) and Pseudomonas aeruginosa (66.67%). Statistical analyses of bark and leaf extract demonstrated antimicrobial activity against both gram-positive (p = 0.000) and gram-negative bacteria (p = 0.012). Extract of bark (p = 0.075) or leaf (p = 0.005) associated with ACA antibiotic showed antimicrobial activity against gram-positive bacteria. Our study suggests that the bark and leaf extracts contain bioactive compounds with antimicrobial activity against multidrug resistant strains.

Detection of AmpC β-lactamase producing bacteria isolated in neonatal sepsis

OBJECTIVE

The objective of this study was to determine the occurrence and antimicrobial profile of AmpC β-lactamase producing bacteria.

METHODS

The study was conducted at The Children's Hospital and The Institute of Child Health Lahore, Pakistan, during September 2011 to June 2012. A total number of 1,914 blood samples of suspected neonatal septicemia were processed. Isolates were identified using Gram's staining, API 20E and API 20NE tests. Gram negative isolates were screened for AmpC β-lactamase production against ceftazidime, cefotaxime and cefoxitin resistance and confirmed by inhibitor based method.

RESULTS

Total number of 54 (8.49%) Gram positive and 582 (91.5%) Gram negative bacteria were identified. Among Gram negative isolates 141 (22%) were AmpC producers and found to be 100% resistant to co-amoxiclav, cefoxitin, ceftazidime, cefotaxime, cefuroxime, cefixime, ceftriaxone, cefpodoxime, gentamicin, amikacin and aztreonam. Less resistance was observed against cefepime (30.4%), sulbactam-cefoperazone (24.8%), piperacillin-tazobactam (10.6%), ciprofloxacin (20.5%) and meropenem (2.1%). All the isolates were found sensitive to imipenem. The patients harbored AmpC β-lactamases were on various interventions in which intravenous line was noted among (51.1%), naso-gastric tube (37.6%), ambu bag (8.5%), endotracheal tube (3.5%), ventilator (2.1%) and surgery (0.7%).

CONCLUSION

Extensive use of invasive procedures and third generation cephalosporins should be restricted to avoid the emergence of AmpC beta-lactamases in neonates.

Evaluation of therapeutic potentials of plant extracts against poultry bacteria threatening public health

BACKGROUND

Plant extracts were evaluated on poultry bacteria known to be threatening public health. This is to develop better bio-therapeutic agents from plant origin.

METHODS

Bacteria were isolated from water, feed, crop, gizzard and faeces of layer chicken. Isolates of interest (Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa and Klebsiella oxytoca) were subjected to antibiotic susceptibility test. Resistant strains were further evaluated against different plant extracts in comparison to Meropenem (control) using agar diffusion method.

RESULTS

E. coli had the highest occurrence (53 %), followed by P. aeruginosa (25 %) and then S. enteritidis (13 %) while the least was K. oxytoca (9 %). Virtually all the isolates exhibited multi-antibiotic resistance (MAR) with gross resistance to Amoxicillin, Erythromycin and Cefuroxine. P. aeruginosa (75 %), S. enteritidis (75 %) and E. coli (63 %), had the highest MAR. Out of the 11 (100 %) plant extracts evaluated, 7 (64 %) were outstanding and showed varied levels of antibacterial activity. Specifically, methanol extract of Mangifera indica Julie cultivar leaf (MJLM) had the highest antibacterial activity, followed by Euadenia trifoliata stem bark (TB03) and Euadenia eminens leaf (TB05). P. aeruginosa was highly susceptible (81.81 %) to the extracts, followed by S. enteritidis (63.64 %) and then E. coli (27.27 %).

CONCLUSIONS

MJLM and other extracts have proven to be promising extracts in which to search for bioactive components that can be developed into therapeutic drugs. This may help in the management of antibiotic resistant bacterial isolates from poultry chicken threatening public health.

Impact of a targeted isolation strategy at intensive-care-unit-admission on intensive-care-unit-acquired infection related to multidrug-resistant bacteria: a prospective uncontrolled before-after study

Isolation of patients with multidrug resistant (MDR) bacteria is recommended to reduce cross-transmission of these bacteria. However, isolation of critically ill patients has several negative side effects. Therefore, we hypothesized that a targeted isolation strategy, based on the presence of at least one risk factor for MDR bacteria, would be not inferior to a systematic isolation strategy at intensive-care unit (ICU) admission. This prospective before-after study was conducted in a mixed ICU, during two 12-month periods, separated by a 1-month 'wash-out' period. During the before period, isolation was systematically performed in all patients at admission. During the after period, isolation was only performed in patients with at least one risk factor for MDR bacteria at admission. During the two periods, routine screening for MDR bacteria was performed at ICU admission, and isolation prescription was modified after receipt of screening result. Primary outcome was the percentage of patients with ICU-acquired infection (ICUAI) related to MDR bacteria, measured from ICU admission until ICU discharge or day 28, whatever happens first. A total of 1221 patients were included. No significant difference was found in ICUAI related to MDR bacteria (85 of 585 (14.5%) vs. 84 of 636 (13.2%) patients, risk difference, -1.3%, 95% confidence interval [-5.2 to 2.6%]) between the two periods, confirming the non-inferiority hypothesis. Our results suggest that targeted isolation of patients at ICU admission is not inferior to systematic isolation, regarding the percentage of patients with ICUAI related to MDR bacteria. Further randomized controlled multicentre studies are needed to confirm our results.

Bacterial Cytological Profiling (BCP) as a Rapid and Accurate Antimicrobial Susceptibility Testing Method for Staphylococcus aureus

Successful treatment of bacterial infections requires the timely administration of appropriate antimicrobial therapy. The failure to initiate the correct therapy in a timely fashion results in poor clinical outcomes, longer hospital stays, and higher medical costs. Current approaches to antibiotic susceptibility testing of cultured pathogens have key limitations ranging from long run times to dependence on prior knowledge of genetic mechanisms of resistance. We have developed a rapid antimicrobial susceptibility assay for Staphylococcus aureus based on bacterial cytological profiling (BCP), which uses quantitative fluorescence microscopy to measure antibiotic induced changes in cellular architecture. BCP discriminated between methicillin-susceptible (MSSA) and -resistant (MRSA) clinical isolates of S. aureus (n = 71) within 1–2 h with 100% accuracy. Similarly, BCP correctly distinguished daptomycin susceptible (DS) from daptomycin non-susceptible (DNS) S. aureus strains (n = 20) within 30 min. Among MRSA isolates, BCP further identified two classes of strains that differ in their susceptibility to specific combinations of beta-lactam antibiotics. BCP provides a rapid and flexible alternative to gene-based susceptibility testing methods for S. aureus, and should be readily adaptable to different antibiotics and bacterial species as new mechanisms of resistance or multidrug-resistant pathogens evolve and appear in mainstream clinical practice.

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Bacterial cytological profiling identifies antibiotic resistant S. aureus.

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BCP predicts best treatment options for multidrug resistant MRSA.

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Resistant strains are correctly identified within 1 h.

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BCP does not require prior knowledge of resistance mechanism.

There is a great need for rapid antimicrobial susceptibility testing (AST) as it can dramatically improve clinical outcome for bacterial infections. Most currently proposed ASTs are dependent on knowledge of known resistance genes or based solely on growth/lysis. We have developed a new diagnostic method for rapidly determining antibiotic susceptibility of Staphylococcus aureus using quantitative fluorescence microscopy to measure antibiotic induced changes in cellular architecture. Our test has the potential to change the way antibiotic susceptibility testing is done in the future and is readily adaptable to different antibiotics and bacterial species regardless of the mechanisms of resistance.

Potential of phage cocktails in the inactivation of Enterobacter cloacae--An in vitro study in a buffer solution and in urine samples

The objective of this study was to compare the dynamics of three previously isolated phages for Enterobacter cloacae in order to evaluate their ability to treat urinary tract infections (UTI). The phages genomes, survival, host range, were characterized, and the host-phage dynamics was determined in culture medium and urine samples. The presence of prophages in bacteria, host recovery and development of resistance to phage after treatment was also evaluated. The growth of the E. cloacae was inhibited by the three phages, resulting in a decrease of ≈3 log. The use of cocktails with two or three phages was significantly more effective (decrease of ≈4 log). In urine, the inactivation was still effective (≈2 log). Both phages were considered safe to inactivate the bacteria (no integrase and toxin codifying genes). Some bacteria remained viable in the presence of the phages, but their colonies were smaller than those of the non-treated control and were visible only after 5 days of incubation (visible after 24h in the control). A high bacterial inactivation efficiency with phage cocktails combined with the safety of the phages and their long periods of survival, even in urine samples, paves the way for depth studies, especially in vivo studies, to control urinary tract infection and to overcome the development of resistances by the nosocomial bacterium E. cloacae.

Hospital outpatient clinics as a potential hazard for healthcare associated infections

Healthcare acquired infections are no longer confined to the hospital environment. Recently, many reported outbreaks have been linked to outpatient settings and attributed to non-adherence to recommended infection-prevention procedures. This study was divided into two parts: The first is a descriptive cross-sectional part, to assess the healthcare personnel's knowledge and compliance with Standard Precautions (SP). The second is an intervention part to assess the role of health education on reducing the level of environmental and reusable medical equipment bacterial contamination. Assessment of the doctors' and nurses' knowledge and compliance with SP was performed using a self-administered questionnaire. Assessment of environmental cleaning (EC) and reusable medical equipment disinfection has been performed using aseptic swabbing method. The extent of any growth was recorded according to the suggested standards: (A) Presence of indicator organisms, with the proposed standard being <1cfu/cm(2). These include Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus, MRSA), Enterococci, including vancomycin-resistant Enterococci (VRE) and various multidrug-resistant Gram-negative bacilli. (B) Aerobic colony count, the suggested standard is <5cfu/cm(2). The effect of health education intervention on cleaning and disinfection had been analyzed by comparing the difference in cleaning level before and after interventional education. Good knowledge and compliance scores were found in more than 50% of participants. Primary screening found poor EC and equipment disinfection as 67% and 83.3% of stethoscopes and ultrasound transducers, respectively, were contaminated with indicator organisms. For all indicator organisms, a significant reduction was detected after intervention (p=0.00). Prevalence of MRSA was 38.9% and 16.7%, of the total S. aureus isolates, before and after intervention, respectively. Although 27.8% of the total Enterococcus isolates were VRE before intervention, no VRE isolates were detected after intervention. These differences were significant. Development and monitoring of the implementation of infection prevention policies and training of HCP is recommended.

The analysis of distribution of multidrug resistant Pseudomonas and Bacillus species from burn patients and burn ward environment

INTRODUCTION

Infections caused by multidrug resistant bacteria act as a risk factor for mortality in burns patients. So keeping in view the crucial importance of reliable therapeutic decisions of multidrug resistance bacteria and role of hospital environment in bacteria colonization, our study is based on the evaluation of distribution of Pseudomonas sp. and Bacillus sp. in burn patients and burn ward environment.

METHODS

The present prospective analysis was conducted on the patients undergoing treatment in the Burn ward of Pt. B.D. Sharma University of Health Sciences, Rohtak, Haryana, during the period of January 2012 to March 2013. The multidrug resistant bacteria were characterized by following the CLSI guidelines. Molecular identification isolates were done by amplifying and sequencing 16S rDNA.

RESULTS

In our study out of 510 samples of 280 burn patients, 263 samples were observed sterile and bacterial isolates were obtained from 247 samples. In burn patients out of 247 samples 43 MDR strains, and in burn ward out of 60 samples 4 MDR strain were observed. After 16S rDNA amplification of MDR isolates the prevalent bacterium was belonged to the genus Bacillus (8 species; 26 isolates) followed by genus Pseudomonas (5 species; 17 isolates). The burn ward environment isolates were Pseudomonas aeruginosa, Pseudomonas stutzeri, Bacillus cereus and Acinetobacter baumanii.

CONCLUSION

The major finding of our study is the predominance of B. cereus followed by P. aeruginosa in burn patients of Pt. B.D. Sharma University of Health Sciences, Rohtak, Haryana. While considering the role of hospital environment, no direct role of environmental isolates was observed in transfer of bacterial infection.

Antibiotic resistance determinants of multidrug-resistant Acinetobacter baumannii clinical isolates in Algeria

Antibiotic susceptibility testing was performed on 71 Acinetobacter baumannii clinical isolates, and presence of antibiotic resistance genes was screened for by PCR amplification and sequencing. Resistance rates were very high for aminoglycosides (22-80%), fluoroquinolones (>90%), and cephalosporins (>90%) but remained low for rifampin (2.8%) or null for colistin. Antibiotic resistance encoding genes detected were as follows: blaTEM-128 gene (74.6%), aph(3')-VI (50.7 %), aadA (63.4%), ant(2″)-I (14.1%), aac(3)-Ia (91.1%), aac(6')-Ib (4.2%), mutation Ser83Leu in gyrA (94.4%), double mutations Ser83Leu and Ser80Leu (or Ser84Leu) in gyrA and parC (69.0%), and mutation I581N in RRDR of the rpoB gene.