Antimicrobial resistance in the intensive care unit: mechanisms, epidemiology, and management of specific resistant pathogens

Predicting permeation of compounds across the outer membrane of P. aeruginosa using molecular descriptors

The ability Gram-negative pathogens have at adapting and protecting themselves against antibiotics has increasingly become a public health threat. Data-driven models identifying molecular properties that correlate with outer membrane (OM) permeation and growth inhibition while avoiding efflux could guide the discovery of novel classes of antibiotics. Here we evaluate 174 molecular descriptors in 1260 antimicrobial compounds and study their correlations with antibacterial activity in Gram-negative Pseudomonas aeruginosa. The descriptors are derived from traditional approaches quantifying the compounds' intrinsic physicochemical properties, together with, bacterium-specific from ensemble docking of compounds targeting specific MexB binding pockets, and all-atom molecular dynamics simulations in different subregions of the OM model. Using these descriptors and the measured inhibitory concentrations, we design a statistical protocol to identify predictors of OM permeation/inhibition. We find consistent rules across most of our data highlighting the role of the interaction between the compounds and the OM. An implementation of the rules uncovered in our study is shown, and it demonstrates the accuracy of our approach in a set of previously unseen compounds. Our analysis sheds new light on the key properties drug candidates need to effectively permeate/inhibit P. aeruginosa, and opens the gate to similar data-driven studies in other Gram-negative pathogens.

Ceragenins and Ceragenin-Based Core-Shell Nanosystems as New Antibacterial Agents against Gram-Negative Rods Causing Nosocomial Infections

The growing number of infections caused by multidrug-resistant bacterial strains, limited treatment options, multi-species infections, high toxicity of the antibiotics used, and an increase in treatment costs are major challenges for modern medicine. To remedy this, scientists are looking for new antibiotics and treatment methods that will effectively eradicate bacteria while continually developing different resistance mechanisms. Ceragenins are a new group of antimicrobial agents synthesized based on molecular patterns that define the mechanism of antibacterial action of natural antibacterial peptides and steroid-polyamine conjugates such as squalamine. Since ceragenins have a broad spectrum of antimicrobial activity, with little recorded ability of bacteria to develop a resistance mechanism that can bridge their mechanism of action, there are high hopes that this group of molecules can give rise to a new family of drugs effective against bacteria resistant to currently used antibiotics. Experimental data suggests that core-shell nanosystems, in which ceragenins are presented to bacterial cells on metallic nanoparticles, may increase their antimicrobial potential and reduce their toxicity. However, studies should be conducted, among others, to assess potential long-term cytotoxicity and in vivo studies to confirm their activity and stability in animal models. Here, we summarized the current knowledge on ceragenins and ceragenin-containing nanoantibiotics as potential new tools against emerging Gram-negative rods associated with nosocomial infections.

Prevalence of Multidrug-Resistant Pathogens Causing Neonatal Early and Late Onset Sepsis, a Retrospective Study from the Tertiary Referral Children's Hospital

Introduction

Sepsis is the most severe infectious disease with the highest mortality rate, particularly among neonates admitted to the neonatal intensive care unit (NICU). This study retrospectively analyzed the epidemiology, antibiotic resistance profiles, and prevalence of multidrug-resistant (MDR) bacteria isolated from blood or cerebrospinal fluid (CSF) cultures in order to evaluate the appropriateness of initial empirical therapy for neonatal sepsis.

Methods

A retrospective study was conducted in the NICU from January 1, 2015, to December 31, 2022. Microbiological data from patients admitted to the NICU were anonymously extracted from the Laboratory of Microbiology database. Neonatal sepsis was classified into two types: early-onset sepsis (EOS), which occurs within the first 72 hours of life, and late-onset sepsis (LOS) for those begins later.

Results

A total of 679 bacterial strains, 543 from blood and 136 from CSF, were detected in 631 neonates. Among these, 378 isolates (55.67%) were Gram-positive bacteria, and 301 isolates (44.33%) were Gram-negative bacteria. The most frequently isolated pathogens were Coagulase-negative staphylococci (CoNS) (36.52%), followed by Klebsiella pneumoniae (20.47%) and Escherichia coli (13.84%). In EOS, 121 strains were found, CoNS represented the majority (33.88%), followed by Klebsiella pneumoniae (23.97%) and Escherichia coli (8.26%). Early-onset septicemia exhibited 67 (55.37%) MDR bacteria. In LOS, 558 strains were isolated, CoNS represented the majority of pathogens (37.10%), followed by Klebsiella pneumoniae (19.71%) and Escherichia coli (15.05%). Late-onset septicemia showed 332 (59.50%) MDR bacteria. High rates of MDR were found in CoNS (76.21%), carbapenem-resistant Klebsiella pneumoniae (66.91%), and MRSA (33.33%).

Conclusion

The study revealed an alarming prevalence of MDR strains isolated from neonatal sepsis, emphasizing the necessity of finding effective prevention and treatment measures. Colistin can be used for MDR Gram-negative bacteria, while vancomycin and teicoplanin can be considered treatment therapies for staphylococcal infections.

Impact of the "Zero Resistance" program on acquisition of multidrug-resistant bacteria in patients admitted to Intensive Care Units in Spain. A prospective, intervention, multimodal, multicenter study

OBJECTIVE

To assess the impact of a multimodal interventional project ("Zero Resistance") on the acquisition of multidrug-resistant bacteria (MDR-B) during the patient's ICU stay.

DESIGN

Prospective, open-label, interventional, multicenter study.

SETTING

103 ICUs.

PATIENTS

Critically ill patients admitted to the ICUs over a 27-month period.

INTERVENTIONS

Implementation of a bundle of 10 recommendations to prevent emergence and spread of MDR-B in the ICU.

MAIN VARIABLE OF INTEREST

Rate of patients acquiring MDR-B during their ICU stay, with differentiation between colonization and infection.

RESULTS

A total of 139,505 patients were included. In 5409 (3.9%) patients, 6020 MDR-B on ICU admission were identified, and in 3648 (2.6%) patients, 4269 new MDR-B during ICU stay were isolated. The rate of patients with MDR-B detected on admission increased significantly (IRR 1.43, 95% CI 1.31-1.56) (p<0.001) during the study period, with an increase of 32.2% between the initial and final monthly rates. On the contrary, the rate of patients with MDR-B during ICU stay decreased non-significantly (IRR 0.93, 95% CI 0.83-1.03) (p=0.174), with a 24.9% decrease between initial and final monthly rates. According to the classification into colonization or infection, there was a highly significant increase of MDR-B colonizations detected on admission (IRR 1.69, 95% CI 1.52-1.83; p<0.0001) and a very significant decrease of MDR-B-infections during ICU stay (IRR 0.67, 95% CI 0.57-0.80, p<0.0001).

CONCLUSIONS

The implementation of ZR project-recommendations was associated with a significantly reduction an infection produced by MDR-B acquired during the patient's ICU stay.

Multidrug-Resistant Bacteria on Critically Ill Patients with Sepsis at Hospital Admission: Risk Factors and Effects on Hospital Mortality

Purpose

To evaluate the effect of MDRO infection on hospital mortality and the risk factors among critically ill patients with sepsis at hospital admission.

Patients and Methods

A cross-sectional study was performed between April 2019 and May 2020, followed by a cohort to evaluate hospital mortality that prospectively included all consecutive patients 18 years or older with sepsis admitted within 48 hours of hospital admission to an adult ICU in Brazil. Patients' characteristics, blood samples within one hour of ICU admission, and microbiological results within 48h of hospital admission were collected. In addition, descriptive statistics, binary logistic regression, and propensity score matching were performed.

Results

At least one MDRO was isolated in 85 patients (9.8%). The extended-spectrum beta-lactamase-producing Enterobacterales are the most frequent organism (56.1%). Hypoxemic acute respiratory failure (OR 1.87, 95% CI 1.02-3.40, p = 0.04), Glasgow Coma Score below 15 (OR 2.57, 95% CI 1.38-4.80, p < 0.01), neoplasm (OR 2.66, 95% CI 1.04-6.82, p = 0.04) and hemoglobin below 10.0 g/dL (OR 1.82, 95% CI 1.05-3.16, p = 0.03) were associated with increased MDRO. Admission from the Emergency Department (OR 0.25, 95% CI 0.14-0.43, p < 0.01) was associated with decreased MDRO. In the multivariate analysis, MDRO at hospital admission increased hospital mortality (OR 2.80, 95% CI 1.05-7.42, p = 0.04). After propensity score-matching adjusted to age, APACHE II, SOFA, and dementia, MDRO at hospital admission was associated with significantly high hospital mortality (OR 2.80, 95% CI 1.05-7.42, p = 0.04). The E-value of adjusted OR for the effect of MDRO infection on hospital mortality was 3.41, with a 95% CI of 1.31, suggesting that unmeasured confounders were unlikely to explain the entirety of the effect.

Conclusion

MDRO infection increased hospital mortality, and MDRO risk factors should be accessed even in patients admitted to ICU within 48 hours of hospital admission.

Prevalence of Multidrug-Resistant Pathogens Causing Bloodstream Infections in an Intensive Care Unit

Introduction

Bloodstream infections are the most severe infections that cause the highest mortality rate, especially in patients admitted to the intensive care unit (ICU). In this study, we aimed to analyze the distribution, resistance patterns and prevalence of MDR (multidrug-resistant) pathogens isolated in blood samples collected from patients with severe invasive infections hospitalized in the ICU.

Methods

A retrospective study of bacterial pathogens was performed on 490 patients admitted to the ICU between 2017 and 2020. The resistance patterns were analyzed using Vitek 2 Compact system.

Results

In total, 617 bacterial isolates were obtained. Four hundred and twenty-seven isolates (69.21%) were Gram positive and 190 isolates (30.79%) were Gram negative bacteria. The most frequently isolated micro-organisms identified in the blood samples for the entire period (2017-2020) were Coagulase-negative staphylococci (CoNS) (318-51.54%), followed by Klebsiella pneumoniae (70-11.34%), Methicillin-Resistant Staphylococcus aureus (MRSA) (58-9.40%), Acinetobacter baumannii (45-7.29%) and Enterococcus faecalis (42-6.80%). The number of Klebsiella pneumoniae strains significantly increased in 2020, compared to the previous year (p < 0.05). The Acinetobacter baumannii prevalence was significantly higher in the age group of 20-64 years (10.89%) and over 65 years (3.53%) (p < 0.001). The difference between the prevalence of CoNS in the elderly (67.84%) and in adults (20-64 years) (52.47%) was also statistically significant (p < 0.001). High rates of MDR were found for Acinetobacter baumannii (97.77%), Pseudomonas aeruginosa (65%), Klebsiella pneumoniae (50%), Enterococcus faecalis (47.61%) and MRSA (46.55%). More than 60% of the Klebsiella pneumoniae strains were found to be resistant to carbapenems.

Conclusion

The study revealed an alarming prevalence of MDR strains isolated in blood samples of the patients admitted to the ICU, indicating the necessity of consistent application of the measures to control.

Phenotypic and genotypic characterisation of cephalosporin-, carbapenem- and colistin-resistant Gram-negative bacterial pathogens in Lebanon, Jordan and Iraq

Antimicrobial resistance (AMR) is a worldwide health concern that continues to escalate. A PubMed literature search identified articles from January 2015-August 2020 reviewing cephalosporin-, carbapenem- and colistin-resistant Gram-negative bacteria (GNB) in Lebanon, Jordan and Iraq, specifically focused on three main pathogens, namely Acinetobacter spp., Enterobacteriaceae (i.e. Escherichia coli and Klebsiella spp.) and Pseudomonas aeruginosa. Sixty-seven relevant articles published within the past 5 years highlighting trends in AMR in Lebanon, Jordan and Iraq were included. Increased resistance to carbapenems in Acinetobacter spp. isolates was observed in Lebanon, Jordan and Iraq; colistin resistance remained relatively low. Studies on Enterobacteriaceae isolates were more varied, with high rates of carbapenem and cephalosporin resistance and lower levels of colistin resistance in Lebanon. Studies from Iraq found high cephalosporin and colistin resistance along with increased susceptibility to carbapenems. In Jordan, most studies recorded high resistance to cephalosporins along with high susceptibility to carbapenems and colistin. Studies on P. aeruginosa isolates were limited: most isolates in Lebanon were carbapenem-resistant and colistin-susceptible; studies in Iraq showed varying levels of resistance to carbapenems and cephalosporins with high susceptibility to colistin; and studies in Jordan found varying levels of susceptibility to carbapenems, cephalosporins and colistin. The most commonly observed resistance mechanisms in GNB were genetic modifications causing increased expression of antimicrobial-inactivating enzymes and decreased permeability. Overall, this review highlights the concerning rise in AMR and the need for improved understanding of the resistance mechanisms to better inform healthcare providers when recommending treatment for patients in this region.

Multimodal intervention to reduce acquisition of carbapenem-non-susceptible Gram-negative bacteria in intensive care units in the National Referral Hospital of Indonesia: An interrupted time series study

PURPOSE

To evaluate a low-cost multimodal intervention on the acquisition of carbapenem-non-susceptible Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa by patients in low-resource intensive care units.

MATERIALS AND METHODS

We performed a quasi-experimental study in a referral hospital in Jakarta, Indonesia: pre-intervention phase 1 (2013-2014), intervention phase 2 (2014-2015) and post-intervention phase 3 (2015-2016). The intervention was hand hygiene promotion and environmental cleaning and disinfection combined with patient disinfection and cohorting. The primary outcome was acquisition of resistant bacteria per 100 patient-days at risk, which was assessed by active microbiological surveillance and analysed with a multilevel Poisson segmented regression model.

RESULTS

In phase 1 (387 patients), the acquisition rate was 4.3/100 days for carbapenem-non-susceptible A. baumannii versus 1.1/100 days for both K. pneumoniae and P. aeruginosa. There was a significant step change from phase 1 to phase 3 (361 patients) in the acquisition of carbapenem-non-susceptible strains, the incidence rate ratio (IRR) was 0.343 (99%CI: 0.164-0.717). This significant change was mainly due to reduced acquisitions of resistant A. baumannii (IRR 0.4, 99%CI: 0.181-1.061). Negative confounding was observed.

CONCLUSION

A multimodal intervention to prevent acquisition of resistant pathogens is feasible and may be effective in ICUs in lower-middle income countries.

Microscopic Approach to Intrinsic Antibiotic Resistance

The emergence of multidrug resistance in Gram-negative pathogens is critically determined by the interplay between efflux pumps activity and low permeation outer membrane. Although phenotypic heterogeneity in isogenic cells is recognized as a key factor of treatment failure, a mathematical framework able to integrate growth dynamics and single-cell heterogeneity in antimicrobial resistance, remains absent. Here we provide such framework that bridges single-cell and colony scales in the context of bacterial survival and efficacy against drugs. Using experimental inputs, our approach produces testable outputs and reveals nontrivial collective effects with key implications for fitness and survival of the colony. This framework provides a mathematical tool to test stress response strategies in organisms that can potentially guide experiments in natural and synthetic cellular systems.

New Polyaminoisoprenyl Antibiotics Enhancers against Two Multidrug-Resistant Gram-Negative Bacteria from Enterobacter and Salmonella Species

A series consisting of new polyaminoisoprenyl derivatives were prepared in moderate to good chemical yields varying from 32 to 64% according to two synthetic pathways: (1) using a titanium-reductive amination reaction affording a 50/50 mixture of cis and trans isomers and (2) a direct nucleophilic substitution leading to a stereoselective synthesis of the compounds of interest. These compounds were then successfully evaluated for their in vitro antibiotic enhancer properties against resistant Gram-negative bacteria of four antibiotics belonging to four different families. The mechanism of action against Enterobacter aerogenes of one of the most efficient of these chemosensitizing agents was precisely evaluated by using fluorescent dyes to measure outer-membrane permeability and to determine membrane depolarization. The weak cytotoxicity encountered led us to perform an in vivo experiment dealing with the treatment of mice infected with Salmonella typhimurium and affording preliminary promising results in terms of tolerance and efficiency of the polyaminoisoprenyl derivative 5r/doxycycline combination.

The effect of temporary closure and enhanced terminal disinfection using aerosolized hydrogen peroxide of an open-bay intensive care unit on the acquisition of extensively drug-resistant Acinetobacter baumannii

Background

At Makassed Hospital’s open-bay intensive care unit (ICU), enhanced terminal disinfection (ETD) using hydrogen peroxide (H₂O₂) was performed without a predefined schedule in extensively-drug-resistant Acinetobacter baumannii (XDR-AB) outbreaks. In this study, we aimed to check for the value of the temporary closure of the ICU and the use of ETD with aerosolized H₂O₂ and Ag⁺ on minimizing the rate of XDR-AB acquisition in patients admitted to the ICU of our facility, which might consequently help us determine the optimal schedule for such procedure in this unit.

Methods

This is a retrospective medical file review of patients admitted to the ICU between January 2016 and May 2018. We divided this period into numerical weeks (NW) after each closure and ETD episode. Risk factors of acquisition (RFA) were determined by comparing the characteristics of patients who acquired XDR-AB to those who didn’t. The proportion of patients residing in each NW was included in the RFA analysis.

Results

Out of 335 patients, 13% acquired XDR-AB. The overall incidence of XDR-AB acquisition was 14.6 cases/1000 patient days. RFA were XDR-AB contact pressure ≥ 3 days [Odds Ratio (OR) = 9.86, 95% Confidence Interval (CI) (3.65–26.64), P < 0.0001)], mechanical ventilation [OR = 4.99, 95%CI (1.76–14.15), P = 0.002)], and having a wound [OR = 3.72, 95%CI (0.99–13.96), P = 0.05)]. Patients who stayed during NW 7,11 and 14 were at risk of acquisition where the odds significantly increased by 6.5, 9.7 and 14.4 folds respectively (P = 0.03,0.01, and 0.01, respectively). We considered NW 7 as the most suitable time for temporary closure of the ICU and ETD with aerosolized H₂O₂.

Conclusion

Contact pressure, mechanical ventilation, and presence of a wound were RFA of XDR-AB. Temporary closure of the ICU with ETD using aerosolized H₂O₂ decreased the rate of XDR-AB acquisition, yet this effect fades away with time. The ETD was shown to be most efficiently done when repeated every 7 calendar weeks in our open-bay ICU as part of a prevention bundle.

Effect of Ceftaroline, Vancomycin, Gentamicin, Macrolides, and Ciprofloxacin against Methicillin-Resistant Staphylococcus aureus Isolates: An In Vitro Study

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection remains a challenging threat because of limited treatment options. Ceftaroline was identified as having potent anti-MRSA activity. Aim: To evaluate the susceptibility of MRSA to gentamicin, macrolides, ciprofloxacin, vancomycin, and ceftaroline and to perform molecular characterization of different resistance genes as aminoglycoside modifying enzyme genes, ermA and ermC, and vanA and vanB genes. Patients and Methods: One hundred non-duplicate MRSA strains were isolated from different samples of hospitalized patients in Cairo University teaching hospitals from November 2015 to August 2016. Determination of antibiotic susceptibility was done using disk diffusion test and minimum inhibitory concentration followed by detection of resistance genes by multiplex polymerase chain reaction (PCR). Results: Of 100 MRSA isolates, 63 (63%) were resistant to gentamicin, erythromycin, clindamycin, and ciprofloxacin, however, all were sensitive to ceftaroline. Fifteen isolates (15%) were vancomycin intermediate resistant and were sensitive to ceftaroline as well. Conclusion: Ceftaroline was potent against MRSA, which was found to be non-susceptible to vancomycin, ciprofloxacin, erythromycin, clindamycin, and gentamicin and it may represent a successful treatment for MRSA infections.

Pseudomonas aeruginosa in the ICU: prevalence, resistance profile, and antimicrobial consumption

INTRODUCTION

Pseudomonas aeruginosa is one of the main pathogens causing infection in intensive care units (ICUs) and usually presents antimicrobial resistance.

METHODS

Data were obtained from ICUs between 2010 and 2013.

RESULTS

P. aeruginosa had a prevalence of 14.5% of which 48.7% were multidrug resistant. We observed increasing resistance to carbapenems and polymyxin B and growing consumption of aminoglycosides, meropenem, ceftazidime, and polymyxin B. The regression impact between resistance and consumption was significant with respect to amikacin, imipenem, meropenem, and polymyxin B.

CONCLUSIONS

Monitoring antimicrobial consumption and resistant microorganisms should be reinforced to combat antimicrobial- and multi-drug resistance.

[Analysis of the predictive value of preventive isolation criteria in the intensive care unit]

OBJECTIVE

To assess the diagnostic accuracy of the criteria used to detect patients carrying multiresistant microorganisms (MRMs).

DESIGN

A prospective observational study was carried out from May 2014 to May 2015.

SETTING

Polyvalent Intensive Care Unit.

PATIENTS

A cohort of consecutively admitted patients meeting the following criteria for preventive isolation according to the "Zero Resistance" project: hospital length of stay>4 days in the last three months ("hospital"); antibiotherapy during one week in the last month ("antibiotic"); institutionalized patients or recurrent contact with healthcare ("institution or care"); MRM carrier in the last 6 months ("previous MRM").

VARIABLES

Demographic data, culture results and isolation time. A multivariate analysis was performed using multiple logistic regression between each of the risk factors and patient MRM carrier status.

RESULTS

During the study period, 575 patients were admitted, of which 28% met the isolation criteria (162). Fifty-one (31%) were MRM carriers. Of the patients who did not meet the criteria, 29 (7%) were carriers. In the multivariate analysis, the only variable independently associated to carrier status was "previous MRM", with OR=12.14 (95%CI 4.24-34.77).

CONCLUSIONS

The only criterion independently associated with the ability to detect patients with MRMs upon admission to the ICU was the existence of "previous MRM".

Multidrug efflux pumps: structure, function and regulation

Infections arising from multidrug-resistant pathogenic bacteria are spreading rapidly throughout the world and threaten to become untreatable. The origins of resistance are numerous and complex, but one underlying factor is the capacity of bacteria to rapidly export drugs through the intrinsic activity of efflux pumps. In this Review, we describe recent advances that have increased our understanding of the structures and molecular mechanisms of multidrug efflux pumps in bacteria. Clinical and laboratory data indicate that efflux pumps function not only in the drug extrusion process but also in virulence and the adaptive responses that contribute to antimicrobial resistance during infection. The emerging picture of the structure, function and regulation of efflux pumps suggests opportunities for countering their activities.

Prevalence of Candida blood stream infections among children in tertiary care hospital: detection of species and antifungal susceptibility

Background

Of all blood stream infections (BSI), candidaemia poses the greatest threat with a high fatality rate among children. There has been an increase in the number of reports of non-C. albicans species and antifungal resistance has progressively emerge.

Aim

The present study aimed to demonstrate the prevalence of candidaemia among children and to characterize the involved species and their susceptibility to antifungal agents.

Methodology

Microbes were isolated from blood samples and identified via standard microbiological procedures. Chromogenic media was used to characterize the Candida species. The susceptibility of the isolates to the antifungal agents; caspofungin, amphotericin, itraconazole, and fluconazole was determined with the E-test.

Statistical methods

The data were analysed with Statistical Package for the Social Science SPSS; SPSS Inc., Chicago, IL, USA) version 15 for Microsoft Windows. Comparisons between the study groups were performed using the Chi square (χ²) test. p-values less than 0.05 were considered significant.

Results

Candidaemia accounted for 17.3% of all BSIs. C. albicans and non-C. albicans species accounted for 36% and 64% of the cases of candidaemia, respectively. Caspofungin, amphotericin, itraconazole, and fluconazole antifungals had activities of 99%, 97%, 73% and 64%, respectively. In total, 64% of patients with candiaemia died.

Conclusion

The prevalence of candidaemia was high, the fatality rate was alarming and non-C. albicans species were predominant. Fluconazole was the least effective of the tested antifungal agents owing to the high level of resistance.

Antimicrobial resistance trends in methicillin-resistant and methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidisisolates obtained from patients admitted to intensive care units. 2010-2015

Introducción. La aparición y la diseminación de cepas resistentes en hospitales, principalmente en unidades de cuidado intensivo (UCI), se han convertido en un serio problema de salud pública.Objetivo. Analizar la tendencia de los fenotipos de resistencia de Staphylococcus aureus y Staphylococcus epidermidis resistentes y susceptibles a meticilina aislados en pacientes atendidos en UCI de un hospital de alta complejidad de Cartagena, Colombia, del 2010 al 2015.Materiales y métodos. Estudio analítico transversal realizado entre enero de 2010 y diciembre de 2015. Se utilizaron aislamientos de S. aureus y S. epidermidis meticilino-susceptibles y meticilino-resistentes (SARM, SASR, SERM y SESM). La técnica de susceptibilidad empleada fue el método microdilución en caldo para la detección de la concentración mínima inhibitoria.Resultados. Se identificaron 313 aislamientos de Staphylococcus spp., la mayoría resistentes a meticilina (63.6%). Las cepas SARM y SERM correspondieron al 13.7% y al 27.8% del total de aislamientos, respectivamente. Los mayores porcentajes de resistencia en SARM y SERM correspondieron a eritromicina (57.6% y 81.2%, respectivamente), clindamicina (54.6% y 71.0%), ciprofloxacina (48.4% y 36.4%) y trimetoprima-sulfametoxazol (36.4% y 51.4%).Conclusión. Los resultados encontrados sugieren el replanteamiento de las estrategias de control de la resistencia antimicrobiana en el hospital objeto de estudio.

T2Bacteria magnetic resonance assay for the rapid detection of ESKAPEc pathogens directly in whole blood

Objectives

To evaluate the magnetic resonance-based T2Bacteria Panel assay for direct detection of ESKAPEc (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) pathogens in blood samples of patients with suspected bloodstream infection (BSI).

Patients and methods

Adult patients admitted to the Emergency Medicine Department, Infectious Diseases Unit and ICU of a large tertiary-care hospital were included if they had a blood culture (BC) ordered concomitantly with a whole-blood sample for T2Bacteria testing. Results were compared with those of BC and other clinically relevant information.

Results

A total of 140 samples from 129 BSI patients were studied. Single bacteria were detected in 15.7% (22/140) and 12.1% (17/140), and multiple bacteria in 2.9% (4/140) and 1.4% (2/140), of samples tested by T2Bacteria and BC, respectively. With respect to the six target (ESKAPEc) species, overall sensitivity and specificity of T2Bacteria across all detection channels in comparison with BC were 83.3% and 97.6%, respectively; these values increased to 89.5% and 98.4%, respectively, when a true-infection criterion (i.e. the same microorganism detected only by T2Bacteria was cultured from another sample type reflecting the source of infection) was used as the comparator. There were 808 T2Bacteria detection results across 112 samples, with concordant negative results, yielding a negative predictive value of 99.8%. The mean time to negative result was 6.1 ± 1.5 h, whereas the mean time to detection/species identification was 5.5 ± 1.4 h.

Conclusions

The T2Bacteria Panel assay has the potential to provide accurate and timely diagnosis of ESKAPEc bacteraemia, which might support the direct therapeutic management of BSI patients.

Outer Membrane Porins

The transport of small molecules across membranes is essential for the import of nutrients and other energy sources into the cell and, for the export of waste and other potentially harmful byproducts out of the cell. While hydrophobic molecules are permeable to membranes, ions and other small polar molecules require transport via specialized membrane transport proteins . The two major classes of membrane transport proteins are transporters and channels. With our focus here on porins-major class of non-specific diffusion channel proteins , we will highlight some recent structural biology reports and functional assays that have substantially contributed to our understanding of the mechanism that mediates uptake of small molecules, including antibiotics, across the outer membrane of Enterobacteriaceae . We will also review advances in the regulation of porin expression and porin biogenesis and discuss these pathways as new therapeutic targets.

Comparison in outcome with tailored antibiotic prophylaxis postoperatively in pediatric intestinal transplant population

BIs are ubiquitous among the pediatric intestinal transplant patient population. Personalizing postoperative prophylaxis antibiotic regimens may improve outcomes in this population. A retrospective analysis of all pediatric patients who underwent intestinal transplantation was evaluated to compare standardized and tailored regimens of antibiotics provided as prophylaxis postoperatively. Patients in the standard group have both shorter time to and higher rate of BIs, which was statistically significant (P < 0.001). Of the children who developed a BI, there was no statistical difference in average times to the development of a second BI (293 vs 119 days, P = 0.211). The tailored group had prolonged times until the development of a MDRO (52.6 vs 63.9 days, P = 0.677). Although not statistically significant, the tailored group had a propensity to present with gram-negative pathogens after transplant as compared to the standard regimen group, which presented with gram-positive pathogens (P = 0.103). Children with a history of an MDRO held a 7.3 (P < 0.01) times more likelihood of death within a year of transplant. A tailored prophylactic antibiotic regimen in the post-transplant period appears to prolong the time to the first BI. Although the data do not show differences in mortality, further study may prove the impact of a tailored antibiotic regimen on morbidity and mortality rates.

Unveiling the fate of adhering bacteria to antimicrobial surfaces: expression of resistance-associated genes and macrophage-mediated phagocytosis

Since most antibacterial coatings reported to fight biomaterial-associated infections (BAI) fail in completely preventing bacterial colonization, it is crucial to know the impact of that small fraction of adhered bacteria in BAI recrudescence. This study aims to understand the fate of Staphylococcus aureus able to adhere to an antimicrobial coating previously developed, in terms of potential development of bacterial resistance and their macrophage-mediated phagocytosis. Antimicrobial coating comprised the co-immobilization of Palm peptide and DNase I onto polydimethylsiloxane. Expression of genes associated to resistance and virulence mechanisms showed that cells in contact with antimicrobial surfaces for a long period of 30 days, exhibit genes equally or less expressed, as compared to cells recovered from control surfaces. Recovered cells also exhibit the same susceptibility patterns, which strengthens the evidence of no resistance development. Remarkably, cells adhered to modified surfaces shows a reduced metabolic activity upon vancomycin treatment unlike the cells found on control surfaces, which can be identified as a clinical opportunity for prophylactically administration after implant surgery. Furthermore, results highlight that functionalization of PDMS with Palm and DNase I should not compromise the action of host immune cells. The overall results reinforce the potential of this antimicrobial strategy to fight BAI.

Bacteremia in cirrhotic patients with upper gastrointestinal bleeding

BACKGROUND/AIMS

Increased risk of bacterial infection is common in cirrhotic patients with upper gastrointestinal bleeding (UGIB). Our study aimed to explore the association of the bacteremia with in-hospital mortality and risk factors of bacteremia in these patients.

MATERIALS AND METHODS

In our retrospective cohort study, we collected data for cirrhotic patients with UGIB admitted to our hospital between August 2010 and December 2010. The primary outcome was in-hospital mortality. The secondary outcome was bacteremia. A multivariate logistic regression analysis was performed to determine risk factors for mortality and bacteremia.

RESULTS

A total of 202 patients with cirrhosis presenting with UGIB at the emergency department (ED) were enrolled. Bacteremia was associated with a higher mortality rate (adjusted odds ratio [OR]: 9.7; 95% confidence interval [CI]: 1.9-50.6, p=0.007), whereas shock (systolic blood pressure <90 mmHg at ED triage) and bandemia (>0% immature neutrophils of band form) were associated with bacteremia in cirrhotic patients with UGIB (adjusted OR: 5.3; 95% CI: 2.3-12.7, p<0.0001 and adjusted OR: 4.0; 95% CI: 1.6-9.9, p=0.0003, respectively).

CONCLUSION

Bacteremia in cirrhotic patients with UGIB is one of the major risk factors leading to in-hospital mortality. On the basis of our findings, prevention of bacteremia in cirrhotic patients with UGIB, especially in those with shock and bandemia, is important; thus, adequate antibiotic treatment is suggested.

Methicillin-resistant Staphylococcus aureus isolated from an intensive care unit in Minas Gerais, Brazil, over a six-year period

To characterize methicillin-resistant Staphylococcus aureus isolates from an intensive care unit of a tertiary-care teaching hospital, between 2005 and 2010. A total of 45 isolates were recovered from patients admitted to the intensive care unit in the study period. Resistance rates higher than 80% were found for clindamycin (100%), erythromycin (100%), levofloxacin (100%), azithromycin (97.7%), rifampin (88.8%), and gentamycin (86.6%). The SCCmec typing revealed that the isolates harbored the types III (66.7%), II (17.8%), IV (4.4%), and I (2.2%). Four (8.9%) isolates carried non-typeable cassettes. Most (66.7%) of the isolates were related to the Brazilian endemic clone from CC8/SCCmec III, which was prevalent (89.3%) between 2005 and 2007, while the USA100/CC5/SCCmec II lineage emerged in 2007 and was more frequent in the last few years. The study showed high rates of antimicrobial resistance among methicillin-resistant S. aureus isolates and the replacement of Brazilian clone, a well-established hospital lineage, by the USA100 in the late 2000s, at the intensive care unit under study.

[Antibiotic transport and membrane permeability: new insights to fight bacterial resistance]

A main challenge in medicinal chemistry is to determine the parameters modulating the in cellulo drug concentration needed for a therapeutic action. In Gram-negative antibacterial research, the concern is to evaluate the antibiotic permeation across the outer and inner membranes, that delineate the periplasm surrounding the bacterial cytoplasm. Passing through the membrane barrier to reach the inhibitory concentration inside the bacterium is the first pivotal step for antibiotics. The research and the development of new antimicrobials mostly rely on their capacity to reach critical concentrations in the vicinity of their intracellular target. Despite several decades of studies focused on antibiotic/drug activity against bacterial cells using different approaches, no consensus regarding the analysis of the kinetics and accumulation in individual bacterium and in bacterial populations is available to understand the drug translocation into living bacteria as a first step of drug action. Our TRANSLOCATION consortium supports the development of reliable and robust methods to quantify penetration and efflux processes in Gram-negative bacteria and recently we have developed a reliable and efficient method to determine the intra-bacterial concentration of fluorescent antibiotics. By using these powerful approaches, new concepts, "Resident Time Concentration Close to Target" (RTC2T) and "Structure Intracellular Concentration Activity Relationship" (SICAR), have been proposed in order to link chemical and structural aspects with the bacterial membrane and transport aspects. Using RTC2T and SICAR indexes, a new dissection of antibiotic translocation-transport can be obtained to better understand and improve the antibiotic pharmacophoric groups that are related to permeation and efflux.

High burden of antimicrobial resistance among gram negative bacteria causing healthcare associated infections in a critical care unit of Nepal

Background

Healthcare associated infections (HCAI) and antimicrobial resistance are principal threats to the patients of intensive care units and are the major determining factors for patient outcome. They are associated with increased morbidity, mortality, excess hospitalization and financial costs. The present study is an attempt to investigate the spectrum and antimicrobial resistance of bacterial isolates involved in healthcare associated infections (HCAI) in the patients of a critical care unit at a tertiary care university hospital in Kathmandu, Nepal.

Methods

A laboratory based study was conducted over the period of 15 months (January 2014 to March 2015) among the patients of intensive care unit of Tribhuvan University Teaching Hospital, Kathmandu, Nepal. Clinical specimens from patients with suspected healthcare-associated infection were processed and bacterial isolates were identified with standard microbiological methods. Antimicrobial susceptibilities of the isolated strains were determined according to the CLSI guidelines and β-lactamases (ESBL, AmpC, MBL and KPC) were detected by various phenotypic tests.

Results

One hundred and forty nine clinical specimens received from 135 patients suspected of HCAI (out of 491 patients) were found with significant bacterial growth. Specimens were from patients suspected of hospital-acquired pneumonia (16%, 79/491), bloodstream infections (5.7%, 28/491), surgical site infections (4.7%, 23/491), and urinary tract infections (3.9%, 19/491). Acinetobacter spp., Klebsiella spp., Escherichia coli and Burkholderia cepacia were the leading bacterial pathogens. Extremely high level of drug resistance (95.8%) along with the production of β-lactamases (ESBL; 43.7%, AmpC; 27.5%), MBL; 50.2% and KPC; 4.2%) was observed among Gram negative bacterial isolates.

Conclusion

Healthcare associated infections are very common in our ICU. Gram negative bacterial pathogens are major culprits associated with these infections and there is alarming state of drug resistance among these isolates. Continuous surveillance and establishment of preventive and control measures of healthcare associated infections are urgently needed in our setting.

Genomic characterization and assessment of the virulence and antibiotic resistance of the novel species Paenibacillus sp. strain VT-400, a potentially pathogenic bacterium in the oral cavity of patients with hematological malignancies

BACKGROUND

Paenibacillus sp. strain VT-400, a novel spore-forming bacterium, was isolated from patients with hematological malignancies.

METHODS

Paenibacillus sp. strain VT-400 was isolated from the saliva of four children with acute lymphoblastic leukemia. The genome was annotated using RAST and the NCBI Prokaryotic Genome Annotation Pipeline to characterize features of antibiotic resistance and virulence factors. Susceptibility to antibiotics was determined by the Kirby-Bauer disc diffusion method. We used a mouse model of pneumonia to study virulence in vivo. Mice were challenged with 7.5 log10-9.5 log10 CFU, and survival was monitored over 7 days. Bacterial load was measured in the lungs and spleen of surviving mice 48 h post-infection to reveal bacterial invasion and dissemination.

RESULTS

Whole-genome sequencing revealed a large number of virulence factors such as hemolysin D and CD4+ T cell-stimulating antigen. Furthermore, the strain harbors numerous antibiotic resistance genes, including small multidrug resistance proteins, which have never been previously found in the Paenibacillus genus. We then compared the presence of antibiotic resistance genes against results from antibiotic susceptibility testing. Paenibacillus sp. strain VT-400 was found to be resistant to macrolides such as erythromycin and azithromycin, as well as to chloramphenicol and trimethoprim-sulphamethoxazole. Finally, the isolate caused mortality in mice infected with ≥8.5 log10 CFU.

CONCLUSIONS

Based on our results and on the available literature, there is yet no strong evidence that shows Paenibacillus species as an opportunistic pathogen in immunocompromised patients. However, the presence of spore-forming bacteria with virulence and antibiotic resistance genes in such patients warrants special attention because infections caused by spore-forming bacteria are poorly treatable.

Treatment of Gram-negative pneumonia in the critical care setting: is the beta-lactam antibiotic backbone broken beyond repair?

Beta-lactam antibiotics form the backbone of treatment for Gram-negative pneumonia in mechanically ventilated patients in the intensive care unit. However, this beta-lactam antibiotic backbone is increasingly under pressure from emerging resistance across all geographical regions, and health-care professionals in many countries are rapidly running out of effective treatment options. Even in regions that currently have only low levels of resistance, the effects of globalization are likely to increase local pressures on the beta-lactam antibiotic backbone in the near future. Therefore, clinicians are increasingly faced with a difficult balancing act: the need to prescribe adequate and appropriate antibiotic therapy while reducing the emergence of resistance and the overuse of antibiotics. In this review, we explore the burden of Gram-negative pneumonia in the critical care setting and the pressure that antibiotic resistance places on current empiric therapy regimens (and the beta-lactam antibiotic backbone) in this patient population. New treatment approaches, such as systemic and inhaled antibiotic alternatives, are on the horizon and are likely to help tackle the rising levels of beta-lactam antibiotic resistance. In the meantime, it is imperative that the beta-lactam antibiotic backbone of currently available antibiotics be supported through stringent antibiotic stewardship programs.

Monoterpenes as nitrofurantoin resistance modulating agents: minimal structural requirements, molecular dynamics simulations, and the effect of piperitone on the emergence of nitrofurantoin resistance in Enterobacteriaceae

The effects of different monoterpenes and 2-cyclohexen-1-one on the antibacterial activity of nitrofurantoin against resistant Enterobacter cloacae, were compared and the minimal structural component of monoterpene required for the highest level of resistance-modulating activity was determined. Subinhibitory concentrations of all compounds tested enhanced the antibacterial activity of nitrofurantoin against E. cloacae to different extents. The highest synergistic effect was observed for the monoterpenes, like piperitone, which contained a conjugated ketone and C=C bond in their carbon ring structure. Piperitone also suppressed the emergence of nitrofurantoin-resistant strains of Enterobacteriaceae that were mutagenized by ethyl methanesulfonate. The modes of interaction of carvone, piperitone, and an enzyme inhibitor, benzoate, with nitroreductase were investigated by molecular docking and molecular dynamic (MD) simulation for 20 ns. MD simulation supported greater stability of the benzoate and monoterpene-nitroreductase (NR) complexes than of free NR. The results of this investigation are promising for the synthesis of more effective lead compounds to enhance the antibacterial activity of nitro drugs against resistant Enterobacter strains.

Risk of Bacterial Infection in Patients With Cirrhosis and Acute Variceal Hemorrhage, Based on Child-Pugh Class, and Effects of Antibiotics

BACKGROUND & AIMS

Antibiotics frequently are overused and are associated with serious adverse events in patients with cirrhosis. However, these drugs are recommended for all patients presenting with acute variceal hemorrhage (AVH). We investigated whether patients should be stratified for antibiotic prophylaxis based on Child-Pugh scores, to estimate risks of bacterial infection, rebleeding, and mortality, and whether antibiotics have equal effects on patients of all Child-Pugh classes. We performed a sensitivity analysis using model for end-stage liver disease (MELD) scores.

METHODS

In a retrospective study, we analyzed data from 381 adult patients with cirrhosis and AVH (70% men; mean age, 56 y), admitted from 2000 through 2009 to 2 tertiary care hospitals in Edmonton, Alberta, Canada. We excluded patients with bacterial infection on the day of AVH. The association between antibiotic prophylaxis and outcomes was adjusted by liver disease severity and by a propensity score.

RESULTS

The patients included in the study had mean MELD scores of 16, and 54% received antibiotic prophylaxis. Overall, antibiotic therapy was associated with lower risks of infection (adjusted odds ratio, 0.37; 95% confidence interval, 0.91-0.74) and mortality (adjusted odds ratio, 0.63; 95% confidence interval, 0.31-1.29). Among patients categorized as Child-Pugh class A given antibiotics, only 2% developed infections and the mortality rate was 0.4%. Among patients categorized as Child-Pugh class B given antibiotics, 6% developed infections, compared with 14% of patients who did not receive antibiotics; antibiotics did not affect mortality. Administration of antibiotics to patients categorized as Child-Pugh class C reduced infections and mortality by approximately 50%, compared with patients who did not receive antibiotics. MELD scores were not as useful as Child-Pugh class in identifying patients at risk for infection.

CONCLUSIONS

Based on a retrospective analysis of patients with cirrhosis and AVH, those categorized as Child-Pugh class A had lower rates of bacterial infection and lower mortality rates in the absence of antibiotic prophylaxis than patients categorized as classes B or C. The recommendation for routine antibiotic prophylaxis for this subgroup requires further evaluation.

Microbiological analysis of bile and its impact in critically ill patients with secondary sclerosing cholangitis

OBJECTIVES

Secondary sclerosing cholangitis in critically ill patients (SSC-CIP) is an emerging disease entity with unfavourable outcome. Our aim was to analyze the microbial spectrum in bile of patients with SSC-CIP and to evaluate the potential impact on the empiric antibiotic treatment in these patients.

METHODS

169 patients (72 patients with SSC-CIP and 97 patients with primary sclerosing cholangitis (PSC)) were included in a prospective observational study between 2010 and 2013. Bile was obtained during endoscopic retrograde cholangiography (ERC) and microbiologically analyzed.

RESULTS

Patients with SSC displayed a significantly different microbiological profile in bile. Enterococcus faecium, Pseudomonas aeruginosa and non-albicans species of Candida were more frequent in SSC compared to patients with PSC (p < 0.05). Patients with SSC showed a higher incidence of drug or multi-drug resistant organisms in bile (p = 0.001). The antimicrobial therapy was adjusted in 64% of patients due to resistance or presence of microorganisms not covered by the initial therapy regimen.

CONCLUSIONS

Patients with SSC-CIP have a distinct microbial profile in bile. Difficult to treat organisms are frequent and an ERC with bile fluid collection for microbiological analysis should be considered in case of insufficient antimicrobial treatment.

Live genomics for pathogen monitoring in public health

Whole genome analysis based on next generation sequencing (NGS) now represents an affordable framework in public health systems. Robust analytical pipelines of genomic data provides in short laps of time (hours) information about taxonomy, comparative genomics (pan-genome) and single polymorphisms profiles. Pathogenic organisms of interest can be tracked at the genomic level, allowing monitoring at one-time several variables including: epidemiology, pathogenicity, resistance to antibiotics, virulence, persistence factors, mobile elements and adaptation features. Such information can be obtained not only at large spectra, but also at the "local" level, such as in the event of a recurrent or emergency outbreak. This paper reviews the state of the art in infection diagnostics in the context of modern NGS methodologies. We describe how actuation protocols in a public health environment will benefit from a "streaming approach" (pipeline). Such pipeline would NGS data quality assessment, data mining for comparative analysis, searching differential genetic features, such as virulence, resistance persistence factors and mutation profiles (SNPs and InDels) and formatted "comprehensible" results. Such analytical protocols will enable a quick response to the needs of locally circumscribed outbreaks, providing information on the causes of resistance and genetic tracking elements for rapid detection, and monitoring actuations for present and future occurrences.

Effects of vitamin b6 therapy for sepsis patients with linezolid-associated cytopenias: a retrospective study

Background

The common adverse effects of linezolid for treating septic patients with gram-positive cocci is anemia and thrombocytopenia, which limit its clinical application.

Objectives

We determined the effects of vitamin B6 adjunctive therapy on linezolid-associated cytopenias, and retrospectively studied 75 septic patients who received at least 7 days of linezolid treatment.

Methods

Patients were divided into a linezolid treatment group (LTG; n = 41) that received linezolid only and a combination treatment group (CTG; n = 34) that received both linezolid and vitamin B6. Each group was further subdivided into those with sepsis and those with severe sepsis. Each patient had red blood cell (RBC), hemoglobin (Hb), hematocrit (Hct), and platelet (PLT) measurements at baseline (day 0) and every other day for 2 weeks during treatment; these parameters were compared between the groups and assessed for time-dependent trends.

Results

For patients in the LTG, RBC, Hb, and Hct values showed statistically significant reductions over time, and these values were lower compared with the values in the CTG. The CTG also showed downward trends, except on the first day of treatment. The PLT count also decreased in both groups. Patients with severe sepsis had lower PLT counts in both treatment groups compared with the septic patients.

Conclusions

Septic patients who received a combination treatment of linezolid and vitamin B6 might show positive effects for linezolid-associated reductions in some hematologic parameters (RBC, Hb, and Hct). This combined treatment might also slow PLT reduction, which was more evident in patients with severe sepsis. ClinicalTrials.gov identifier: NCT01295801.

Severe sepsis facilitates intestinal colonization by extended-spectrum-β-lactamase-producing Klebsiella pneumoniae and transfer of the SHV-18 resistance gene to Escherichia coli during antimicrobial treatment

Infections caused by multidrug-resistant pathogens are frequent and life threatening in critically ill patients. To investigate whether severe sepsis affects gut colonization by resistant pathogens and genetic exchange between opportunistic pathogens, we tested the intestinal-colonization ability of an extended-spectrum beta-lactamase-producing Klebsiella pneumoniae strain carrying the SHV-18 resistance gene and the transfer ability of the resistance gene to endogenous Escherichia coli under ceftriaxone treatment in rats with burn injury only or severe sepsis induced by burns plus endotoxin exposure. Without ceftriaxone treatment, the K. pneumoniae strain colonized the intestine in both septic and burned rats for a short time, with clearance occurring earlier in burn-only rats but never in sham burn rats. In both burned and septic rats, the colonization level of the challenge strain dropped at the beginning and then later increased during ceftriaxone treatment, after which it declined gradually. This pattern coincided with the change in resistance of K. pneumoniae to ceftriaxone during and after ceftriaxone treatment. Compared with burn-only injury, severe sepsis had a more significant effect on the change in antimicrobial resistance to ceftriaxone. Only in septic rats was the resistance gene successfully transferred from the challenge strain to endogenous E. coli during ceftriaxone treatment; the gene persisted for at least 4 weeks after ceftriaxone treatment. We concluded that severe sepsis can facilitate intestinal colonization by an exogenous resistant pathogen and the transfer of the resistance gene to a potential endogenous pathogen during antimicrobial treatment.

High-level aminoglycoside resistance and virulence characteristics among Enterococci isolated from recreational beaches in Malaysia

We report the first study on the occurrence of high-level aminoglycoside-resistant (HLAR) Enterococci in coastal bathing waters and beach sand in Malaysia. None of the encountered isolates were resistant to high levels of gentamicin (500 μg/mL). However, high-level resistance to kanamycin (2,000 μg/mL) was observed in 14.2 % of tested isolates, the highest proportions observed being among beach sand isolates. High-level resistance to kanamycin was higher among Enterococcus faecalis and Enterococcus faecium than Enterococcus spp. Chi-square analysis showed no significant association between responses to tested antibiotics and the species allocation or source of isolation of all tested Enterococci. The species classification of encountered Enterococci resistance to vancomycin was highest among Enterococcus spp. (5.89 %) followed by E. faecium (4.785) and least among E. faecalis. A total of 160 isolates were also tested for virulence characteristics. On the whole, caseinase production was profoundly highest (15.01 %) while the least prevalent virulence characteristic observed among tested beach Enterococci was haemolysis of rabbit blood (3.65 %). A strong association was observed between the source of isolation and responses for each of caseinase (C = 0.47, V = 0.53) and slime (C = 0.50, V = 0.58) assays. Analysis of obtained spearman's coefficient showed a strong correlation between caseinase and each of the slime production (p = 0.04), gelatinase (p = 0.0035) and haemolytic activity on horse blood (p = 0.004), respectively. Suggestively, these are the main virulent characteristics of the studied beach Enterococci. Our findings suggest that recreational beaches may contribute to the dissemination of Enterococci with HLAR and virulence characteristics.

High prevalence of antibiotic-resistant bacterial infections among patients with cirrhosis at a US liver center

BACKGROUND & AIMS

There are limited data on the prevalence or predictors of antibiotic-resistant bacterial infections (AR-BI) in hospitalized patients with cirrhosis in North America. Exposure to systemic antibiotics is a risk factor for AR-BI; however, little is known about the effects of the increasingly used oral nonabsorbed antibiotics.

METHODS

We analyzed data from patients with cirrhosis and bacterial infections hospitalized in a liver unit at a US hospital between July 2009 and November 2010. Multivariate logistic regression was used to determine predictors of AR-BI. Data were analyzed on the first bacterial infection of each patient (n = 115), and a sensitivity analysis was performed on all infectious episodes per patient (n = 169).

RESULTS

Thirty percent of infections were nosocomial. Urinary tract infections (32%) and spontaneous bacterial peritonitis (24%) were most common. Of the 70 culture-positive infections, 33 (47%) were found to be antibiotic resistant (12 were vancomycin-resistant Enterococci, 9 were extended-spectrum β-lactamase-producing Enterobacteriaceae, 7 were quinolone-resistant gram-negative rods, and 5 were methicillin-resistant Staphylococcus aureus). Exposure to systemic antibiotics within 30 days before infection was associated independently with AR-BI, with an odds ratio (OR) of 13.5 (95% confidence interval [CI], 2.6-71.6). Exposure to only nonabsorbed antibiotics (rifaximin) was not associated with AR-BI (OR, 0.4; 95% CI, 0.04-2.8). In a sensitivity analysis, exposure to systemic antibiotics within 30 days before infection and nosocomial infection was associated with AR-BI (OR, 5.2; 95% CI, 1.5-17.7; and OR, 4.2; 95% CI, 1.4-12.5, respectively).

CONCLUSIONS

The prevalence of AR-BI is high in a US tertiary care transplant center. Exposure to systemic antibiotics within 30 days before infection (including those used for prophylaxis of spontaneous bacterial peritonitis), but not oral nonabsorbed antibiotics, is associated with development of an AR-BI.

Outbreak of extended spectrum beta-lactamase-producing Klebsiella pneumoniae in an intensive care unit (Brest)

INTRODUCTION

We had for aim to describe control and investigation of an outbreak caused by a strain of Extended spectrum beta-lactamase producing Klebsiella pneumoniae in intensive care units of the Brest teaching hospital.

PATIENTS AND METHOD

The case definition was a patient infected by or carrying the epidemic strain. Control measures and investigations are presented. A case-control study was conducted in the surgical intensive care unit. Each case was matched with two controls based on admission times in the unit. The study focused on diagnostic and therapeutic procedures, and potential contacts with healthcare workers, in this context of cross transmission.

RESULTS

Between February and May 2011, nine cases were reported in the surgical ICU and two in the medical ICU. Eighteen controls were matched with the nine surgical ICU cases. Several factors were found to be statistically associated with infection or colonization by the epidemic strain: the surgical block in which patients had been operated and the ward of first hospitalization; the number of trans-esophageal and trans-thoracic echocardiographies, of central venous catheter insertions, and of surgical operations; intubation. The total number of invasive procedures was also found to be statistically higher among cases.

CONCLUSION

This study identified factors associated with colonization or infection by the epidemic strain. These factors might have been involved in the transmission tree, and be vulnerable elements for the prevention of nosocomial infections and colonisations, and their epidemic spread.

Antibiotic therapy in neonatal and pediatric septic shock

Severe sepsis accounts for nearly 4,500 deaths (mortality rate 10%), and is responsible for nearly $2 billion annual healthcare expenditure in the United States. Early and speedy treatment of critically ill septic patients can halt or reduce the likelihood of physiologic progression to multi-system organ failure. A cornerstone of this therapeutic strategy is antibiotic administration. In this review, we discuss the empirical treatment strategies for the treatment of early and late neonatal sepsis, along with pediatric sepsis. Furthermore, we discuss the rationale that underlies the adoption of such treatment strategies. The present article also discusses the emergence of multi-drug organisms as the causative agents for sepsis, i.e. methicillin-resistant Staphylococcus aureus (MRSA), resistant enterococci and Klebsiella pneumoniae carbapenemases (KPC).

A rapid in situ procedure for determination of bacterial susceptibility or resistance to antibiotics that inhibit peptidoglycan biosynthesis

Background

Antibiotics which inhibit bacterial peptidoglycan biosynthesis are the most widely used in current clinical practice. Nevertheless, resistant strains increase dramatically, with serious economic impact and effects on public health, and are responsible for thousands of deaths each year. Critical clinical situations should benefit from a rapid procedure to evaluate the sensitivity or resistance to antibiotics that act at the cell wall. We have adapted a kit for rapid determination of bacterial DNA fragmentation, to assess cell wall integrity.

Results

Cells incubated with the antibiotic were embedded in an agarose microgel on a slide, incubated in an adapted lysis buffer, stained with a DNA fluorochrome, SYBR Gold and observed under fluorescence microscopy. The lysis affects the cells differentially, depending on the integrity of the wall. If the bacterium is susceptible to the antibiotic, the weakened cell wall is affected by the lysing solution so the nucleoid of DNA contained inside the bacterium is released and spread. Alternatively, if the bacterium is resistant to the antibiotic, it is practically unaffected by the lysis solution and does not liberate the nucleoid, retaining its normal morphological appearance. In an initial approach, the procedure accurately discriminates susceptible, intermediate and resistant strains of Escherichia coli to amoxicillin/clavulanic acid. When the bacteria came from an exponentially growing liquid culture, the effect on the cell wall of the β-lactam was evident much earlier that when they came from an agar plate. A dose-response experiment with an E. coli strain susceptible to ampicillin demonstrated a weak effect before the MIC dose. The cell wall damage was not homogenous among the different cells, but the level of damage increased as dose increased with a predominant degree of effect for each dose. A microgranular-fibrilar extracellular background was evident in gram-negative susceptible strains after β-lactam treatment. This material was digested by DNase I, hybridised with a specific whole genome probe, and so recognized as DNA fragments released by the bacteria. Finally, 46 clinical strains from eight gram-negative and four gram-positive species were evaluated blind for susceptibility or resistance to one of four different β-lactams and vancomycin, confirming the applicability of the methodology.

Conclusion

The technique to assess cell wall integrity appears to be a rapid and simple procedure to identify resistant and susceptible strains to antibiotics that interfere with peptidoglycan biosynthesis.