Resistance patterns among nosocomial pathogens: trends over the past few years

Significant reduction of the culturing time required for bacterial identification and antibiotic susceptibility determination by infrared spectroscopy

Rapid testing of bacteria for antibiotic susceptibility is essential for effective treatment and curbing the emergence of multidrug-resistant bacteria. The misuse of antibiotics, coupled with the time-consuming classical testing methods, intensifies the threat of antibiotic resistance, a major global health concern. In this study, employing infrared spectroscopy-based machine learning techniques, we significantly shortened the time required for susceptibility testing to 10 hours, a significant improvement from the 24 hours in our previous studies as well as the conventional methods that typically take at least 48 hours. This remarkable reduction in turnaround time (from 48 hours to 10 hours), achieved by minimizing the culturing period, offers a game-changing advantage for clinical applications. Our study involves a dataset comprising 400 bacterial samples (200 E. coli, 100 Klebsiella pneumoniae, and 100 Pseudomonas aeruginosa) with an impressive 96% accuracy in the taxonomic classification at the species level and up to 82% accuracy in bacterial susceptibility to various antibiotics.

The therapeutic effect of engineered phage, derived protein and enzymes against superbug bacteria

Defending against antibiotic-resistant infections is similar to fighting a war with limited ammunition. As the new century unfolded, antibiotic resistance became a significant concern. In spite of the fact that phage treatment has been used as an effective means of fighting infections for more than a century, researchers have had to overcome many challenges of superbug bacteria by manipulating phages and producing engineered enzymes. New enzymes and phages with enhanced properties have a significant impact on the ability to fight antibiotic-resistant infections, which is considered a window of hope for the future. This review, therefore, illustrates not only the challenges caused by antibiotic resistance and superbug bacteria but also the engineered enzymes and phages that are being developed to solve these issues. Our study found that engineered phages, phage proteins, and enzymes can be effective in treating superbug bacteria and destroying the biofilm caused by them. Combining these engineered compounds with other antimicrobial substances can increase their effectiveness against antibiotic-resistant bacteria. Therefore, engineered phages, proteins, and enzymes can be used as a substitute for antibiotics or in combination with antibiotics to treat patients with superbug infections in the future.

Detection of extended-spectrum β-lactamase-producing bacteria isolated directly from urine by infrared spectroscopy and machine learning

Resistant bacteria have become one of the leading health threats in the last decades. Extended-spectrum β-lactamase (ESBL) producing bacteria, including Escherichia (E.) coli and Klebsiella (K.) pneumoniae (the most frequent ones), are a significant class out of all resistant infecting bacteria. Due to the widespread and ongoing development of ESBL-producing (ESBL⁺) resistant bacteria, many routinely used antibiotics are no longer effective against them. However, an early and reliable ESBL⁺ bacteria detection method will improve the efficiency of treatment and limit their spread. In this work, we investigated the capability of infrared (IR) spectroscopy based machine learning tools [principal component analysis (PCA) and Random Forest (RF) classifier] for the rapid detection of ESBL⁺ bacteria isolated directly from patients' urine. For that, we examined 1881 E. coli samples (416 ESBL⁺ and 1465 ESBL^-) and 609 K. pneumoniae samples (237 ESBL⁺ and 372 ESBL^-). All samples were isolated directly from the urine of midstream patients. This study revealed that within 40 min of receiving the patient urine it is possible to determine the infecting bacterium as E. coli or K. pneumoniae with 95% success rate while it was possible to determine the ESBL⁺E. coli and ESBL⁺K. pneumoniae with 83% and 78% accuracy rates, respectively.

Bacterial distribution and drug resistance in blood samples of children in Jiangxi Region, 2017-2021

Objective

This study aims to investigate the distribution and drug resistance of bacteria in clinical blood culture specimens from children in Jiangxi province in recent years and to provide a foundation for preventing and treating bloodstream infection diseases in children.

Methods

The study involved a statistical analysis of the isolation and drug resistance of bacterial strains obtained from blood culture specimens of children in Jiangxi province between 2017 and 2021. The analysis was performed using the WHONET 5.6 software.

Results

A total of 7,977 bacterial strains were isolated from the blood samples of children between 2017 and 2021. Of these, 2,334 strains (29.3%) were identified as Gram-negative bacteria, and 5,643 strains (70.7%) were identified as Gram-positive bacteria. The most commonly isolated pathogens were coagulase-negative Staphylococcus, Escherichia coli, and Staphylococcus aureus. Among the Gram-negative bacteria, Escherichia coli (840 strains, 36.0%), Klebsiella pneumoniae (385 strains), Salmonella (283 strains), Acinetobacter baumannii (137 strains), and Pseudomonas aeruginosa (109 strains) were the most prevalent. Among the Gram-positive bacteria, coagulase-negative Staphylococcus (3,424 strains, 60.7%), Staphylococcus aureus (679 strains), Streptococcus pneumoniae (432 strains), Enterococcus sp. (292 strains), and Streptococcus agalactiae (192 strains) were the most common. Resistance to third-generation cephalosporins (cefotaxime/ceftriaxone) was observed in 45.9% and 56.0% of Escherichia coli and Klebsiella pneumoniae strains, respectively, while resistance to carbapenems was observed in 4.6% and 20.3% of these strains, respectively. Resistance to third-generation cephalosporins (cefotaxime/ceftriaxone) was observed in 15.5% of Salmonella strains, while resistance to imipenem was absent. Carbapenem resistance was observed in 17.1% (20/117) and 13% (14/108) of Acinetobacter baumannii and Pseudomonas aeruginosa strains, respectively. Methicillin-resistant Staphylococcus aureus (MRSA) was detected in 32.7% of the strains, while methicillin-resistant coagulase-negative Staphylococcus was detected in 64.3% of the coagulase-negative Staphylococcus strains. No Staphylococcus bacteria resistant to vancomycin were detected. Four strains of vancomycin-resistant Enterococcus faecium were detected over the 5-year period, and one strain of linezolid-resistant Enterococcus faecalis was detected.

Conclusion

Gram-positive cocci were the most commonly isolated clinical pathogens in blood specimens from children in Jiangxi province. The composition of the pathogen species showed a slight change over the years. The detection ratios of pathogens varied with age group and season. Although the isolation rate of common carbapenem-resistant Enterobacter bacteria has decreased, it remains high. It is necessary to monitor the antimicrobial resistance of pathogens causing bloodstream infections in children more closely, and antimicrobial agents should be used with caution.

Nano-Chitosan/Eucalyptus Oil/Cellulose Acetate Nanofibers: Manufacturing, Antibacterial and Wound Healing Activities

Accelerated wound healing in infected skin is still one of the areas where current therapeutic tactics fall short, which highlights the critical necessity for the exploration of new therapeutic approaches. The present study aimed to encapsulate Eucalyptus oil in a nano-drug carrier to enhance its antimicrobial activity. Furthermore, in vitro, and in vivo wound healing studies of the novel nano-chitosan/Eucalyptus oil/cellulose acetate electrospun nanofibers were investigated. Eucalyptus oil showed a potent antimicrobial activity against the tested pathogens and the highest inhibition zone diameter, MIC, and MBC (15.3 mm, 16.0 μg/mL, and 256 μg/mL, respectively) were recorded against Staphylococcus aureus. Data indicated a three-fold increase in the antimicrobial activity of Eucalyptus oil encapsulated chitosan nanoparticle (43 mm inhibition zone diameter against S. aureus). The biosynthesized nanoparticles had a 48.26 nm particle size, 19.0 mV zeta potential, and 0.45 PDI. Electrospinning of nano-chitosan/Eucalyptus oil/cellulose acetate nanofibers was conducted, and the physico-chemical and biological properties revealed that the synthesized nanofibers were homogenous, with a thin diameter (98.0 nm) and a significantly high antimicrobial activity. The in vitro cytotoxic effect in a human normal melanocyte cell line (HFB4) proved an 80% cell viability using 1.5 mg/mL of nano-chitosan/Eucalyptus oil/cellulose acetate nanofibers. In vitro and in vivo wound healing studies revealed that nano-chitosan/Eucalyptus oil/cellulose acetate nanofibers were safe and efficiently enhanced the wound-healing process through enhancing TGF-β, type I and type III collagen production. As a conclusion, the manufactured nano-chitosan/Eucalyptus oil/cellulose acetate nanofiber showed effective potentiality for its use as a wound healing dressing.

Antimicrobial activity of photosensitizers: arrangement in bacterial membrane matters

Porphyrins are well-known photosensitizers (PSs) for antibacterial photodynamic therapy (aPDT), which is still an underestimated antibiotic-free method to kill bacteria, viruses, and fungi. In the present work, we developed a comprehensive tool for predicting the structure and assessment of the photodynamic efficacy of PS molecules for their application in aPDT. We checked it on a series of water-soluble phosphorus(V) porphyrin molecules with OH or ethoxy axial ligands and phenyl/pyridyl peripheral substituents. First, we used biophysical approaches to show the effect of PSs on membrane structure and their photodynamic activity in the lipid environment. Second, we developed a force field for studying phosphorus(V) porphyrins and performed all-atom molecular dynamics simulations of their interactions with bacterial lipid membranes. Finally, we obtained the structure-activity relationship for the antimicrobial activity of PSs and tested our predictions on two models of Gram-negative bacteria, Escherichia coli and Acinetobacter baumannii. Our approach allowed us to propose a new PS molecule, whose MIC₅₀ values after an extremely low light dose of 5 J/cm² (5.0 ± 0.4 μg/mL for E. coli and 4.9 ± 0.8 μg/mL for A. baumannii) exceeded those for common antibiotics, making it a prospective antimicrobial agent.

Instant detection of extended-spectrum β-lactamase-producing bacteria from the urine of patients using infrared spectroscopy combined with machine learning

Antibiotics are considered the most effective treatment against bacterial infections. However, most bacteria have already developed resistance to a broad spectrum of commonly used antibiotics, mainly due to their uncontrolled use. Extended-spectrum beta-lactamase (ESBL)-producing bacteria are an essential class of multidrug-resistant (MDR) bacteria. It is of extreme urgency to develop a method that can detect ESBL-producing bacteria rapidly for the effective treatment of patients with bacterial infectious diseases. Fourier transform infrared (FTIR) microscopy is a sensitive method that can rapidly detect cellular molecular changes. In this study, we examined the potential of FTIR spectroscopy-based machine learning algorithms for the rapid detection of ESBL-producing bacteria obtained directly from a patient's urine. Using 591 ESBL-producing and 1658 non-ESBL-producing samples of Escherichia coli (E. coli) and Klebsiella pneumoniae, our results show that the FTIR spectroscopy-based machine learning approach can identify ESBL-producing bacteria within 40 minutes from receiving a patient's urine sample, with a success rate of 80%.

The Interplay between Host Defense, Infection, and Clinical Status in Septic Patients: A Narrative Review

Sepsis is a life-threatening condition that arises when the body's response to an infection injures its own tissues and organs. Despite significant morbidity and mortality throughout the world, its pathogenesis and mechanisms are not clearly understood. In this narrative review, we aimed to summarize the recent developments in our understanding of the hallmarks of sepsis pathogenesis (immune and adaptive immune response, the complement system, the endothelial disfunction, and autophagy) and highlight novel laboratory diagnostic approaches. Clinical management is also discussed with pivotal consideration for antimicrobic therapy management in particular settings, such as intensive care unit, altered renal function, obesity, and burn patients.

Nosocomial sepsis and drug susceptibility pattern among patients admitted to adult intensive care unit of Ayder Comprehensive Specialized Hospital, Northern Ethiopia

OBJECTIVE

Developing nosocomial sepsis within intensive care unit (ICU) is associated with increased mortality, morbidity, and length of hospital stay. But information is scarce regarding nosocomial sepsis in intensive care units of Northern Ethiopia. Hence, this study aims to determine the incidence of nosocomial sepsis, associated factors, bacteriological profile, drug susceptibility pattern, and outcome among patients admitted to the adult ICU of Ayder Comprehensive Specialized Hospital (ACSH), which is the largest tertiary hospital in Northern Ethiopia.

METHOD

Facility-based longitudinal study was conducted by following 278 patients who were admitted for more than 48 h to adult ICU of ACSH, from October 2016 to October 2017. Data were collected from charts, electronic medical records, and microbiology registration book using a checklist. The collected data were subjected to descriptive statistics and multivariable logistic regression using SPSS version 25. Statistical significance was declared at p < 0.05.

RESULT

Of all the patients, 60 (21.6%) of them acquired nosocomial sepsis. The risk of mortality was about two times higher among adult ICU patients who acquired nosocomial sepsis (RR = 2.2; 95% CI of RR = 1.3-3.5; p = 0.003). The odds of acquiring nosocomial sepsis among those who were on a mechanical ventilator (MV) and stayed more than a week were 5.7 and 9.3 times higher, respectively, than their corresponding counterparts. Among 48 isolates, Klebsiella was the most common pathogen. The isolates had a broad antibiotic resistance pattern for cephalosporins, penicillins, and methicillin.

CONCLUSION

The incidence of nosocomial sepsis in the adult ICU patients of ACSH was higher when compared to the incidence reported from some African and Asian countries. Mortality was higher among patients who acquired nosocomial sepsis. Use of MV and longer length of ICU stay were the significant predictors of nosocomial sepsis. The isolates were resistant to several antibiotics. Therefore, strict application of infection prevention strategies and appropriate use of antibiotics is so crucial. As well, priority should be given to patients who develop nosocomial sepsis in ICU.

Rapid detection of Klebsiella pneumoniae producing extended spectrum β lactamase enzymes by infrared microspectroscopy and machine learning algorithms

Antimicrobial drugs have played an indispensable role in decreasing morbidity and mortality associated with infectious diseases. However, the resistance of bacteria to a broad spectrum of commonly-used antibiotics has grown to the point of being a global health-care problem. One of the most important classes of multi-drug resistant bacteria is Extended Spectrum Beta-Lactamase-producing (ESBL+) bacteria. This increase in bacterial resistance to antibiotics is mainly due to the long time (about 48 h) that it takes to obtain lab results of detecting ESBL-producing bacteria. Thus, rapid detection of ESBL+ bacteria is highly important for efficient treatment of bacterial infections. In this study, we evaluated the potential of infrared microspectroscopy in tandem with machine learning algorithms for rapid detection of ESBL-producing Klebsiella pneumoniae (K. pneumoniae) obtained from samples of patients with urinary tract infections. 285 ESBL+ and 365 ESBL-K. pneumoniae samples, gathered from cultured colonies, were examined. Our results show that it is possible to determine that K. pneumoniae is ESBL+ with ∼89% accuracy, ∼88% sensitivity and ∼89% specificity, in a time span of ∼20 minutes following the initial culture.

Drug resistance of pathogens causing nosocomial infection in orthopedics from 2012 to 2017: a 6-year retrospective study

Background

Hospital-acquired infections (HAIs) are an emerging global problem that increases in-hospital mortality, length of stay, and cost. We performed a 6-year retrospective study to provide valuable insight into appropriate antibiotic use in HAI cases. We also aimed to understand how hospitals could reduce pathogen drug resistance in a population that overuses antibiotics.

Methods

All data (2012–2017) were obtained from the hospital information warehouse and clinical microbiology laboratory.

Results

We isolated 1392 pathogen strains from patients admitted to the orthopedics department during 2012–2017. Escherichia coli (14.7%, 204/1392), Enterobacter cloacae (13.9%, 193/1392), and Staphylococcus aureus (11.3%, 157/1392) were the most common pathogens causing nosocomial infections. The dominant Gram-negative bacterium was E. coli, with high resistance to ampicillin, levofloxacin, cotrimoxazole, gentamicin, and ciprofloxacin, in that order. E. coli was least resistant to amikacin, cefoperazone-sulbactam. The most dominant Gram-positive bacterium was S. aureus, highly resistant to penicillin and ampicillin, but not resistant to fluoroquinolones and cotrimoxazole. Analysis of risk factors related to multidrug-resistant bacteria showed that patients with open fractures (Gustillo III B and IIIC) were significantly more susceptible to methicillin-resistant S. aureus infections (p < 0.05). Additionally, extended-spectrum β-lactamase-producing E. coli infections occurred significantly more often in patients with degenerative diseases (p < 0.05). Elderly patients tended to be more susceptible to multidrug-resistant bacterial infections, but this outcome was not statistically significant.

Conclusions

Antimicrobial resistance is a serious problem in orthopedics. To effectively control antimicrobial resistance among pathogens, we advocate extensive and dynamic monitoring of MDR bacteria, coupled with careful use of antibiotics.

Rare Multidrug-resistant Pseudomonas aeruginosa Identified in a U.S. Deployed Service Member Following Host-nation Medical Treatment

Decision-making related to the utilization of host-nation medical resources in austere forward-deployed environments is complex. Clinical circumstances, local medical intelligence availability, transportation assets, uncertainty regarding standard-of-care variations, military/host-nation funding complications, and regional security concerns all factor into consideration. A case of a U.S. active duty military service member who suffered a cardiac arrest on a military base in Southwest Asia is described in this report. After return of circulation following defibrillation, he was administered thrombolytic therapy for an electrocardiogram-identified ST-elevation myocardial infarction and transported to a local host-nation cardiac hospital for emergent percutaneous coronary intervention. During his subsequent transportation back to the USA, surveillance testing identified that he was colonized with a rare strain of Pseudomonas aeruginosa, demonstrating New Delhi metallo-beta-lactamase-1 and 16S RNA methyltransferase-2 enzymes, which confer significant resistance to carbapenem and aminoglycoside antibiotics, respectively.1-3 This combination of antibiotic resistance has been reported very rarely in the medical literature and has never been reported within the deployed military health system until now. The risk of exposure to multidrug-resistant organisms was not a factor initially considered in the decision to utilize host-nation medical resources in this case, which provided lesson learned and raised new questions, for future operational medical planning.

Silver Sulfadiazine Eradicates Antibiotic-Tolerant Staphylococcus aureus and Pseudomonas aeruginosa Biofilms in Patients with Infected Diabetic Foot Ulcers

Infections are among the most frequent and challenging events in diabetic foot ulcers (DFUs). Pathogenic bacteria growing in biofilms within host tissue are highly tolerant to environmental and chemical agents, including antibiotics. The present study was aimed at assessing the use of silver sulfadiazine (SSD) for wound healing and infection control in 16 patients with DFUs harboring biofilm-growing Staphylococcus aureus and Pseudomonas aeruginosa. All patients received a treatment based on a dressing protocol including disinfection, cleansing, application of SSD, and application of nonadherent gauze, followed by sterile gauze and tibio-breech bandage, in preparation for toilet surgery after 30 days of treatment. Clinical parameters were analyzed by the T.I.M.E. classification system. In addition, the activity of SSD against biofilm-growing S. aureus and P. aeruginosa isolates was assessed in vitro. A total of 16 patients with S. aureus and P. aeruginosa infected DFUs were included in the study. Clinical data showed a statistically significant (p < 0.002) improvement of patients’ DFUs after 30 days of treatment with SSD with significant amelioration of all the parameters analyzed. Notably, after 30 days of treatment, resolution of infection was observed in all DFUs. In vitro analysis showed that both S. aureus and P. aeruginosa isolates developed complex and highly structured biofilms. Antibiotic susceptibility profiles indicated that biofilm cultures were significantly (p ≤ 0.002) more tolerant to all tested antimicrobials than their planktonic counterparts. However, SSD was found to be effective against fully developed biofilms of both S. aureus and P. aeruginosa at concentrations below those normally used in clinical preparations (10 mg/mL). These results strongly suggest that the topical administration of SSD may represent an effective alternative to conventional antibiotics for the successful treatment of DFUs infected by biofilm-growing S. aureus and P. aeruginosa.

Are Stethoscopes, Coats, and Pagers Potential Sources of Healthcare Associated Infections?

We conducted a study to determine the rate of bacterial colonization of stethoscopes, coats, and pagers of residents at a pediatric residency training program as compared to that of badges, sleeves, and pagers of non-patient care staff (control group). Among 213 cultures obtained from 71 residents, 27 potential pathogens were isolated from 22 residents (27/213, 12.7%) as compared to 10 potential pathogens out of 162 samples obtained from 54 control participants (10/162, 6.2%) (P = .0375). The most common pathogen isolated from residents and control participants was methicillin sensitive Staphylococcus aureus (MSSA). The source of positive cultures among the residents was the stethoscope (8/22, 36.3%), pager (8/22, 36.3%), and coat sleeve (11/22, 50%). The rates of colonization with potential pathogens were higher among residents than control participants and about 12% of residents’ stethoscopes, coats and pagers were colonized with bacterial pathogens. These are potential sources of nosocomial transmission of pathogenic organisms.

Safety of laser-generated shockwave treatment for bacterial biofilms in a cutaneous rodent model

Bacterial biofilms are often found in chronically infected wounds. Biofilms protect bacteria from antibiotics and impair wound healing. Surgical debridement is often needed to remove the biofilm from an infected wound. Laser-generated shockwave (LGS) treatment is a novel tissue-sparing treatment for biofilm disruption. Previous studies have demonstrated that LGS is effective in disrupting biofilms in vitro. In this study, we aim to determine the safety threshold of the LGS technology in an in vivo rodent model. To understand the in vivo effects of LGS on healthy cutaneous tissue, the de-haired dorsal skin of Sprague-Dawley rats were treated with LGS at three different peak pressures (118, 296, 227 MPa). These pressures were generated using a 1064 nm Nd/YAG laser (pulse duration 5 ns and laser fluence of 777.9 mJ) with laser spot size diameters of 2.2, 3.0, and 4.2 mm, respectively. Following treatment, the animals were observed for 72 h, and a small subset was euthanized at 1-h, 24-h, and 72-h post-treatment and assessed for tissue injury or inflammation under histology. Each treatment group consisted of 9 rats (n = 3/time point for 1-h, 24-h, 72-h post-treatment). An additional 4 control (untreated) rats were included in the analysis, for a total of 31 animals. Gross injuries occurred in 21 (77%) animals and consisted of minor erythema, with prevalence positively correlated with peak pressure (p < 0.05). Of injuries under gross observation, 94% resolved within 24 h. Under histological analysis, the injuries and tissue inflammation were found to be localized to the epidermis and superficial dermis. LGS appears to be well tolerated by cutaneous tissue for the laser energy settings shown to be effective against bacterial biofilm in vitro. All injuries incurred, at even the highest peak pressures, were clinically mild and resolved within 1 day. This lends further support to the overall safety of LGS and serves to translate LGS towards in vivo efficacy studies.

Gram-Negative Taxa and Antimicrobial Susceptibility after Fecal Microbiota Transplantation for Recurrent Clostridioides difficile Infection

Fecal microbiota transplantation (FMT) has promising applications in reducing multidrug-resistant organism (MDRO) colonization and antibiotic resistance (AR) gene abundance. However, data on clinical microbiology results after FMT are limited. We examined the changes in antimicrobial susceptibility profiles in patients with Gram-negative infections in the year before and the year after treatment with FMT for recurrent Clostridioides difficile infection (RCDI). We also examined whether a history of FMT changed health care provider behavior with respect to culture ordering and antibiotic prescription. Medical records for RCDI patients who underwent FMT at Emory University between July 2012 and March 2017 were reviewed retrospectively. FMT-treated patients with Gram-negative culture data in the 1-year period preceding and the 1-year period following FMT were included. Demographic and clinical data were abstracted, including CDI history, frequency of Gram-negative cultures, microbiological results, and antibiotic prescription in response to positive cultures in the period following FMT. Twelve patients were included in this case series. We pooled data from infections at all body sites and found a decrease in the number of total and Gram-negative cultures post-FMT. We compared susceptibility profiles across taxa given the potential for horizontal transmission of AR elements and observed increased susceptibility to nitrofurantoin, trimethoprim-sulfamethoxazole, and the aminoglycosides. FMT did not drastically influence health care provider ordering of bacterial cultures or antibiotic prescribing practices. We observed a reduction in Gram-negative cultures and a trend toward increased antimicrobial susceptibility. This study supports further investigation of FMT as a means of improving antimicrobial susceptibility.IMPORTANCE Fecal microbiota transplantation (FMT), which is highly efficacious in treating recurrent C. difficile infection (RCDI), has a promising application in decolonization of multidrug-resistant organisms, reduction of antibiotic resistance gene abundance, and restoration of healthy intestinal microbiota. However, data representing clinical microbiology results after FMT are limited. We sought to characterize the differences in culture positivity and antimicrobial susceptibility profiles in patients with Gram-negative infections in the year before and the year after FMT for RCDI. Drawing on prior studies that had demonstrated the success of FMT in eradicating extraintestinal infections and the occurrence of patient-level interspecies transfer of resistance elements, we employed an agnostic analytic approach of reviewing the data irrespective of body site or species. In a small RCDI population, we observed an improvement in the antimicrobial susceptibility profile of Gram-negative bacteria following FMT, which supports further study of FMT as a strategy to combat antibiotic resistance.

Antibacterial Activity of Synthetic Cationic Iron Porphyrins

Widespread antibiotic resistance demands new strategies for fighting infections. Porphyrin-based compounds were long ago introduced as photosensitizers for photodynamic therapy, but light-independent antimicrobial activity of such compounds has not been systematically explored. The results of this study demonstrate that synthetic cationic amphiphilic iron N-alkylpyridylporphyrins exert strong bactericidal action at concentrations as low as 5 μM. Iron porphyrin, FeTnHex-2-PyP, which is well tolerated by laboratory animals, efficiently killed Gram-negative and Gram-positive microorganisms. Its bactericidal activity was oxygen-independent and was controlled by the lipophilicity and accumulation of the compound in bacterial cells. Such behavior is in contrast with the anionic gallium protoporphyrin IX, whose efficacy depends on cellular heme uptake systems. Under aerobic conditions, however, the activity of FeTnHex-2-PyP was limited by its destruction due to redox-cycling. Neither iron released from the Fe-porphyrin nor other decomposition products were the cause of the bactericidal activity. FeTnHex-2-PyP was as efficient against antibiotic-sensitive E. coli and S. aureus as against their antibiotic-resistant counterparts. Our data demonstrate that development of amphiphilic, positively charged metalloporphyrins might be a promising approach in the introduction of new weapons against antibiotic-resistant strains.

Analysis of the Microbiota of the Physiotherapist's Environment

OBJECTIVES

To analyze the microbiota of the physiotherapist's work environment to understand the existing potential risks and to adopt appropriate preventive measures.

DESIGN

Cross-sectional descriptive observational study.

SETTING

Physiotherapist's working environment.

PARTICIPANTS

Physiotherapy and rehabilitation centers (N=19).

INTERVENTIONS

A microbiological sampling was carried out in the physiotherapy centers. The samples were studied using the usual culture and analysis methodology for characterization and isolation of a range of bacteria.

MAIN OUTCOME MEASURES

Absolute and relative frequency of microorganism isolation.

RESULTS

In the analysis, pathogens normally responsible for nosocomial infections were detected, especially on instruments and equipment used by the physiotherapist such as sponge electrodes, and were significantly more contaminated than the rest of the places studied (P<.01).

CONCLUSION

This situation confirms the absence of measures and protocols for the prevention and control of such infections in the physiotherapist's environment, which is why they must be considered to protect both physiotherapy professionals and patients.

A Hybrid Peptide DEFB-TP5 Expressed in Methylotrophic Yeast Neutralizes LPS With Potent Anti-inflammatory Activities

DEFB-TP5 is a novel auspicious health-beneficial peptide derivative from two naturally occurring peptides, β-Defensin (DEFB) and thymopentin (TP5), and shows strong anti-inflammatory activity and binds to LPS without cytotoxicity and hemolytic effect. Furthermore, the application of DEFB-TP5 peptide is inadequate by its high cost. In the current study, we developed a biocompatible mechanism for expression of the DEFB-TP5 peptide in Pichia pastoris. The transgenic strain of hybrid DEFB-TP5 peptide with a molecular weight of 6.7kDa as predictable was obtained. The recombinant DEFB-TP5 peptide was purified by Ni-NTA chromatography, estimated 30.41 mg/L was obtained from the cell culture medium with 98.2% purity. Additionally, The purified DEFB-TP5 peptide significantly (p< 0.05) diminished the release of nitric oxide (NO), TNF-α, IL-6, IL-1β in LPS-stimulated RAW264.7 macrophages in a dose-dependent manner. This study will not only help to understand the molecular mechanism of expression that can potentially be used to develop an anti-endotoxin peptide but also to serve as the basis for the development of antimicrobial and anti-inflammatory agents as well, which also provides a potential source for the production of recombinant bioactive DEFB-TP5 at the industrial level.

Expression and Purification of Hybrid LL-37Tα1 Peptide in Pichia pastoris and Evaluation of Its Immunomodulatory and Anti-inflammatory Activities by LPS Neutralization

This study pertains to the new approach for the development of hybrid peptide LL-37Tα1 and its biomedical applications. A linear cationic hybrid peptide, LL-37Tα1 was derived from two parental peptides (LL-37 and Tα1) recognized as potent anti-endotoxin without any hemolytic or cytotoxic activity. We successfully cloned the gene of hybrid peptide LL-37Tα1 in PpICZαA vector and expressed in the Pichia pastoris. The recombinant peptide was purified by Ni-affinity column and reverse-phase high performance liquid chromatography (RP-HPLC) with an estimated molecular mass of 3.9 kDa as determined by SDS-PAGE and mass spectrometry. We analyzed the LPS neutralization by limulus amebocyte lysate (LAL) activity and the results indicate that the hybrid peptide LL-37Tα1 directly binds endotoxin and significantly (p < 0.05) neutralizes the effect of LPS in a dose-dependent manner. Lactate dehydrogenase (LDH) assay revealed that LL-37Tα1 successfully reduces the LPS-induced cytotoxicity in mouse RAW264.7 macrophages. Moreover, it significantly (p < 0.05) decreased the levels of nitric oxide, proinflammatory cytokines including TNF-α, IL-6, IL-1β, and diminished the number of apoptotic cells in LPS-stimulated mouse RAW264.7 macrophages. Our results suggest that the P. pastoris expression system is cost-effective for commercial production of the immunomodulatory and anti-inflammatory hybrid peptide (IAHP) LL-37Tα1 and the peptide may serve as effective anti-endotoxin/anti-inflammatory agent with minimal cytotoxicity.

Meropenem/colistin versus meropenem/ampicillin-sulbactam in the treatment of carbapenem-resistant pneumonia

AIM

Efficacy of colistin and ampicillin-sulbactam have not been compared in treatment of ventilator-associated pneumonia due to A. baumannii. Efficacy of colistin and ampicillin-sulbactam in combination with meropenem were compared in treatment of ventilator-associated pneumonia due to carbapenem-resistant A. baumannii.

METHOD

47 patients with ventilator-associated pneumonia due to carbapenem-resistant A. baumannii were randomized to receive meropenem/colistin or meropenem/ampicillin-sulbactam for 14 days. Clinical and microbiological responses and 28-day mortality were considered as outcomes.

RESULTS

Clinical response (75 vs 69.6%; p = 0.75) and microbial eradication (87.50 vs 91.3%; p = 0.59) were comparable between meropenem/colistin and meropenem/ampicillin-sulbactam groups, respectively.

CONCLUSION

In this study, clinical and microbiological response were comparable between the meropenem/colistin and meropenem/ampicillin-sulbactam groups.

A review of analytical procedures for the simultaneous determination of medically important veterinary antibiotics in environmental water: Sample preparation, liquid chromatography, and mass spectrometry

Medically important (MI) antibiotics are defined by the United States Food and Drug Administration as drugs containing certain active antimicrobial ingredients that are used for the treatment of human diseases or enteric pathogens causing food-borne diseases. The presence of MI antibiotic residues in environmental water is a major concern for both aquatic ecosystems and public health, particularly because of their potential to contribute to the development of antimicrobial-resistant microorganisms. In this article, we present a review of global trends in the sales of veterinary MI antibiotics and the analytical methodologies used for the simultaneous determination of antibiotic residues in environmental water. According to recently published government reports, sales volumes have increased steadily, despite many countries having adopted strategies for reducing the consumption of antibiotics. Global attention needs to be directed urgently at establishing new management strategies for reducing the use of MI antimicrobial products in the livestock industry. The development of standardized analytical methods for the detection of multiple residues is required to monitor and understand the fate of antibiotics in the environment. Simultaneous analyses of antibiotics have mostly been conducted using high-performance liquid chromatography-tandem mass spectrometry with a solid-phase extraction (SPE) pretreatment step. Currently, on-line SPE protocols are used for the rapid and sensitive detection of antibiotics in water samples. On-line detection protocols must be established for the monitoring and screening of unknown metabolites and transformation products of antibiotics in environmental water.

Impact of fluoroquinolone prophylaxis on infectious-related outcomes after hematopoietic cell transplantation

BACKGROUND

Patients immediately post-hematopoietic cell transplantation are at high risk for bacteremia. Judicious prophylactic antimicrobial utilization must balance anticipated benefits (reduction infections) versus risk (bacterial resistance, Clostridium difficile) .

OBJECTIVE

To compare infectious outcomes (primary: incidence bacteremia; secondary: febrile neutropenia, C. difficile, susceptibility of bacteremia, time to discharge and 30-day mortality) between hematopoietic cell transplantation who received fluoroquinolone prophylaxis to those who did not.

METHODS

A local institutional review board-approved retrospective study was conducted on all hematopoietic cell transplantation patients ( n = 171) comparing those who received fluoroquinolone prophylaxis ( n = 105) to those who did not ( n = 66). Data included infectious outcomes and mortality for the first 30 days post-hematopoietic cell transplantation. Chi-squared was performed for categorical variables (GraphPad Software Inc., 2015). Secondary analysis compared outcomes within autologous and allogeneic sub-groups.

RESULTS

Bacteremia was significantly lower for the overall cohort receiving fluoroquinolone (median duration eight days) versus those without fluoroquinolone (15.2% vs. 31.8%; P < 0.01). No difference was seen in C. difficile infection ( P = 0.81) or 30-day mortality (2.9% vs. 4.5%; P = 0.67). In the autologous sub-group ( n = 115), bacteremia was significantly lower in the fluoroquinolone cohort (8.5% vs. 27.3%; P = 0.0069), while no differences were seen in C. difficile infection ( P = 1) or 30-day mortality ( P = 1). In the allogeneic sub-group ( n = 56), there was no difference between those with and without fluoroquinolone in bacteremia (29.4% vs. 40.9%; P = 0.4) or C. difficile ( P = 0.72); however, there was a trend toward improved 30-day mortality (2.9% vs. 9.1%; P = 0.55).

CONCLUSIONS

Fluoroquinolone prophylaxis reduces incidence of bacteremia in autologous hematopoietic cell transplantation without increasing C. difficile after hematopoietic cell transplantation.

Using Infrared Spectroscopy and Multivariate Analysis to Detect Antibiotics' Resistant Escherichia coli Bacteria

Bacterial pathogens are one of the primary causes of human morbidity worldwide. Historically, antibiotics have been highly effective against most bacterial pathogens; however, the increasing resistance of bacteria to a broad spectrum of commonly used antibiotics has become a global health-care problem. Early and rapid determination of bacterial susceptibility to antibiotics has become essential in many clinical settings and, sometimes, can save lives. Currently classical procedures require at least 48 h for determining bacterial susceptibility, which can constitute a life-threatening delay for effective treatment. Infrared (IR) microscopy is a rapid and inexpensive technique, which has been used successfully for the detection and identification of various biological samples; nonetheless, its true potential in routine clinical diagnosis has not yet been established. In this study, we evaluated the potential of this technique for rapid identification of bacterial susceptibility to specific antibiotics based on the IR spectra of the bacteria. IR spectroscopy was conducted on bacterial colonies, obtained after 24 h culture from patients' samples. An IR microscope was utilized, and a computational classification method was developed to analyze the IR spectra by novel pattern-recognition and statistical tools, to determine E. coli susceptibility within a few minutes to different antibiotics, gentamicin, ceftazidime, nitrofurantoin, nalidixic acid, ofloxacin. Our results show that it was possible to classify the tested bacteria into sensitive and resistant types, with success rates as high as 85% for a number of examined antibiotics. These promising results open the potential of this technique for faster determination of bacterial susceptibility to certain antibiotics.

The Role of Adjunctive Therapies in Septic Shock by Gram Negative MDR/XDR Infections

Patients with septic shock by multidrug resistant microorganisms (MDR) are a specific sepsis population with a high mortality risk. The exposure to an initial inappropriate empiric antibiotic therapy has been considered responsible for the increased mortality, although other factors such as immune-paralysis seem to play a pivotal role. Therefore, beyond conventional early antibiotic therapy and fluid resuscitation, this population may benefit from the use of alternative strategies aimed at supporting the immune system. In this review we present an overview of the relationship between MDR infections and immune response and focus on the rationale and the clinical data available on the possible adjunctive immunotherapies, including blood purification techniques and different pharmacological approaches.

Laser-generated shockwaves enhance antibacterial activity against biofilms in vitro

BACKGROUND AND OBJECTIVES

Bacterial biofilm formation within chronic wound beds, which provides an effective barrier against antibiotics, is a known cause of recalcitrant infections and a significant healthcare burden, often requiring repeated surgical debridements. Laser-generated shockwaves (LGS) is a novel, minimally invasive, and nonthermal modality for biofilm mechanical debridement which utilizes compressive stress waves, generated by photonic absorption in thin titanium films to mechanically disrupt the biofilm. Prior studies have demonstrated LGS monotherapy to be selectively efficacious for biofilm disruption and safe for host tissues. In this study, we sought to determine if LGS can enhance the antimicrobial activity and biofilm disruption capability of topical antibiotic therapy.

STUDY DESIGN/MATERIALS AND METHODS

Staphylococcus epidermidis biofilms grown in vitro on glass were treated with topical gentamicin (31, 62, and 124 μg/ml) with and without LGS (n = 3-11/treatment group). Mechanical shockwaves were generated with a 1,064 nm Nd:YAG laser (laser fluence 110.14 mJ/mm² , pulse duration 5 ns, spot size 3 mm). Following a 24-hour incubation period, bacterial viability was assessed by determining the number of colony-forming units (CFU) via the Miles and Misra method. Residual biofilm bioburden was analyzed using the crystal violet biofilm assay.

RESULTS

With gentamicin monotherapy, CFU density (CFU/mm² ) at 31, 62, and 124 μg/ml were (282 ± 84) × 10⁴ , (185 ± 34) × 10⁴ , and (113 ± 9) × 10⁴ , respectively. With LGS and gentamicin therapy, CFU density decreased to (170 ± 44) × 10⁴ , (89 ± 24) × 10⁴ , and (43 ± 3) × 10⁴ , respectively (P = 0.1704, 0.0302, and 0.0004 when compared with gentamicin alone). Biofilm burden as measured by the assay in the gentamicin 31, 62, and 124 μg/ml groups was reduced by 80%, 95%, and 98% when LGS was added (P = 0.0102, >0.0001, and 0.0001 for all groups when compared with gentamicin alone). Furthermore, samples treated with LGS saw an increase in susceptibility to gentamicin, in terms of reduced biofilm bioburden and CFU densities.

CONCLUSION

LGS enhances the efficacy of topical antibiotics in an in vitro model. This has significant implications for clinical applications in the management of chronic soft tissue infections and recalcitrant chronic rhinosinusitis. Lasers Surg. Med. 49:539-547, 2017. © 2017 Wiley Periodicals, Inc.

Effect of prior receipt of antibiotics on the pathogen distribution and antibiotic resistance profile of key Gram-negative pathogens among patients with hospital-onset urinary tract infections

BACKGROUND

This retrospective cohort study characterized the impact of prior antibiotic exposure on distribution and nonsusceptibility profiles of Gram-negative pathogens causing hospital-onset urinary tract infections (UTI).

METHODS

Hospital patients with positive urine culture for Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and other Enterobacteriaceae ≥3 days after hospital admission were included. Assessment outcomes included the distribution of bacteria in urine cultures, antibiotic susceptibility patterns, and the effect of prior antibiotic exposure, defined as 0, 1, or ≥2 prior antibiotics, on the distribution and antibiotic susceptibility profiles of the Gram-negative organisms.

RESULTS

The most commonly isolated pathogens from 5574 unique UTI episodes (2027 with and 3547 without prior antibiotic exposure) were E. coli (49.5%), K. pneumoniae (17.1%), and P. aeruginosa (8.2%). P. aeruginosa was significantly more commonly isolated in patients with ≥2 prior antibiotic exposures (12.6%) compared with no exposure (8.2%; p = 0.036) or 1 prior exposure (7.9%; p = 0.025). Two or more prior antibiotic exposures were associated with slightly higher incidences of fluoroquinolone nonsusceptibility, multidrug resistance, and extended-spectrum β-lactamase phenotype compared with 0 or 1 exposure, suggesting an increased risk for resistant Gram-negative pathogens among hospital patients with urinary tract infections occurring ≥3 days after admission.

CONCLUSIONS

Clinicians should critically assess prior antibiotic exposure when selecting empirical therapy for patients with hospital-onset urinary tract infections caused by Gram-negative pathogens.

Effects of implementation of an online comprehensive antimicrobial-stewardship program in ICUs: A longitudinal study

BACKGROUND/PURPOSE

The long-term effects of antimicrobial-stewardship programs in the intensive care units (ICUs) have not been adequately examined. We evaluated the impact of an online comprehensive antimicrobial stewardship program (OCASP) on the outcomes of patients in 200-bed medical/surgical ICUs over the course of 11 years.

METHODS

We analyzed the records of adult patients admitted to ICUs during the 5 years before (n = 27,499) and the 6 years after (n = 33,834) implementation of an OCASP. Antimicrobial consumption, expenditures, duration of treatment, incidence of healthcare-associated infections (HAIs), prevalence of HAIs caused by antimicrobial-resistant strains, and crude or sepsis-related mortality of patients were analyzed. Segmented regression analyses of interrupted time series were used to assess the significance of changes in antimicrobial use.

RESULTS

Compared to the patients in the pre-OCASP period, the patients in the post-OCASP period were older, had greater disease severity, longer ICU stays, and were more likely to receive antimicrobials, but had lower antimicrobial expenditures and crude and sepsis-related mortality. The trend of overall antimicrobial use [slope of defined daily dose/1000 patient-days vs. time) increased significantly before OCASP implementation (p < 0.001), but decreased significantly after implementation (p < 0.01). The administration duration of all classes of antibiotics were significantly shorter (p < 0.001) and the incidences of HAIs were significantly lower (p < 0.001) after implementation. However, there was an increase in the proportion of HAIs caused by carbapenem-resistant Acinetobacter baumannii relative to all A. baumannii infections.

CONCLUSION

Implementation of an OCASP in the ICUs reduced antimicrobial consumption and expenditures, but did not compromise healthcare quality.

Impact of Nursing Education on the Proportion of Appropriately Drawn Vancomycin Trough Concentrations

Background:

Few studies have investigated the timing of vancomycin trough concentration collection in the inpatient setting. To date, there are no published studies on the impact of targeted nursing staff education on the appropriate timing of vancomycin trough concentration collection.

Objective:

To evaluate the impact of educational sessions on nursing staff knowledge regarding vancomycin and proper collection of troughs.

Methods:

The nursing staffs of 5 hospital units with a high volume of vancomycin usage were targeted for voluntary vancomycin educational sessions. Comprehension of the educational content was measured by a 5-question pre-/posteducation quiz. Vancomycin trough concentrations were evaluated during a 2-month period pre-/posteducation for appropriate timing of sample draw, defined as ≤45 minutes prior to the next scheduled vancomycin dose.

Results:

A total of 114 nurses participated in the education sessions. The mean pretest score was 3.91 and the mean posttest score was 4.89 ( P < .001). Preeducation, 69% of trough concentrations were collected appropriately. Posteducation, 74% of samples were collected within the 45-minute time frame ( P = .20).

Conclusions:

A significant increase in short-term comprehension regarding vancomycin was seen posteducation. There was a nonsignificant increase in appropriately timed trough concentration collection posteducation. Further education of nursing staffs may be necessary to lessen timing errors.

Antimicrobial Justification form for Restricting Antibiotic Use in a Pediatric Intensive Care Unit

OBJECTIVE

To study whether introduction of an antimicrobial justification form deters clinicians from prescribing restricted antimicrobials and results in de-escalation of these antimicrobials.

METHODS

Clinicians were asked to fill a justification form if prescribing an antimicrobial from the pre-identified restricted group. Antimicrobial usage pattern over next year was compared with that in the one year preceding the introduction of justification form.

RESULTS

Significant overall decrease in antimicrobial usage (40.5% vs 34.6%) was noted in the post-intervention group along with a significant increase in the de-escalation of antibiotics.

CONCLUSION

Introduction of a justification form before prescribing antimicrobials or at the time of deferring de-escalation can be useful in restricting usage of antimicrobials.

Identification of a small molecule that simultaneously suppresses virulence and antibiotic resistance of Pseudomonas aeruginosa

The rising antibiotic resistance of bacteria imposes a severe threat on human health. Inhibition of bacterial virulence is an alternative approach to develop new antimicrobials. Molecules targeting antibiotic resistant enzymes have been used in combination with cognate antibiotics. It might be ideal that a molecule can simultaneously suppress virulence factors and antibiotic resistance. Here we combined genetic and computer-aided inhibitor screening to search for such molecules against the bacterial pathogen Pseudomonas aeruginosa. To identify target proteins that control both virulence and antibiotic resistance, we screened for mutants with defective cytotoxicity and biofilm formation from 93 transposon insertion mutants previously reported with increased antibiotic susceptibility. A pyrD mutant displayed defects in cytotoxicity, biofilm formation, quorum sensing and virulence in an acute mouse pneumonia model. Next, we employed a computer-aided screening to identify potential inhibitors of the PyrD protein, a dihydroorotate dehydrogenase (DHODase) involved in pyrimidine biosynthesis. One of the predicted inhibitors was able to suppress the enzymatic activity of PyrD as well as bacterial cytotoxicity, biofilm formation and antibiotic resistance. A single administration of the compound reduced the bacterial colonization in the acute mouse pneumonia model. Therefore, we have developed a strategy to identify novel treatment targets and antimicrobial molecules.

Differential impact of infection control strategies on rates of resistant hospital-acquired pathogens in critically ill surgical patients

BACKGROUND

There were two major outbreaks of multi-drug resistant Acinetobacter baumannii (MDRA) in our general surgery and trauma intensive care units (ICUs) in 2004 and 2011. Both required aggressive multi-faceted interventions to control. We hypothesized that the infection control response may have had a secondary benefit of reducing rates of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile (C. diff).

METHODS

We analyzed data retrospectively from a prospective infection control database at a major university hospital and calculated the incidence rates of nosocomial MRSA, VRE, and C. diff before and after the two MDRA outbreaks (2004 and 2011) in the general surgery and trauma ICUs, and two unaffected control ICUs: thoracic surgery ICU and medical ICU. We tracked incidence rates in 6 mos segments for 24 mos per outbreak and created a composite variable of "any resistant pathogen" for comparison.

RESULTS

The incidence rates of "any resistant pathogen" were significantly lower in the general surgery ICU after both outbreaks (24 to 11 cases per 1000 patient days in 2004, p=0.045 and 7.7 ->4.0 cases per 1000 patient days in 2011, p=0.04). This did not persist after 6 mos. The trauma ICU's rate of "any resistant pathogen" did not change after either outbreak (16 ->16.5 cases per 1000 patient days in 2004, p=0.44 and 4.6 ->1.9 cases per 1000 patient days in 2011, p=0.41). The rates in the control ICUs were unchanged during the study periods.

CONCLUSIONS

Rates of resistant pathogens were lower in the general surgery ICU after response to MDRA outbreaks in both 2004 and 2011 although the rates increased again with time. There were no changes in rates of resistant pathogens in the trauma ICU after MDRA outbreaks in 2004 and 2011. Outbreak responses may have a differential impact in general surgery ICU versus trauma ICUs.

Microbiology of surgical site infections after gastrointestinal surgery in the south region of The Netherlands

AIM

To give an overview of the microbiology of blood and wound samples from surgical site infections (SSIs) after gastrointestinal surgery, as well as the antimicrobial susceptibility of the microorganisms involved, and to discuss the appropriateness of the prophylactic antibiotics administered.

MATERIALS & METHODS

During a 3.5-year study period, wound swabs and blood samples of patients with an SSI were taken in the first 48 h after surgery until 30 days thereafter.

RESULTS

Most pathogens were isolated from wound swabs. Escherichia coli (25%) and Pseudomonas aeruginosa (10%) were the most frequently found microorganisms. Both microorganisms showed a slight tendency towards a decrease in susceptibility for the tested antibiotics, although after correction, this was not significant.

CONCLUSION

The comparison between wound swabs taken in the first 48 h after a surgical procedure and swabs in the 30 days thereafter provides important information concerning the microbiology of SSIs and the development of antibiotic resistance of the causative agents over time.

Risk Factors and Outcomes Associated with Isolation of Meropenem High-Level-Resistant Pseudomonas aeruginosa

Objective.

To determine risk factors and outcomes for patients with meropenem high–level-resistant Pseudomonas aeruginosa (MRPA) (minimum inhibitory concentration [MIC] ≥ 32 μg/mL).

Design.

Case-control-control.

Setting.

An 867-bed urban, teaching hospital.

Patients.

Fifty-eight MRPA case patients identified from an earlier P. aeruginosa study; 125 randomly selected control patients with meropenem-susceptible P. aeruginosa (MSPA) (MIC ≤ 4 μg/mL), and 57 control patients without P. aeruginosa (sampled by case date/location).

Methods.

Patient data, outcomes, and costs were obtained via administrative database. Cases were compared to each control group while controlling for time at risk (days between admission and culture, or entire length of stay [LOS] for patients without P. aeruginosa).

Results.

A multivariable model predicted risks for MRPA versus MSPA (odds ratio [95% confidence interval]): more admissions (in the prior 12 months) (1.41 [1.15, 1.74]), congestive heart failure (2.19 [1.03, 4.68]), and Foley catheter (2.53 [1.18, 5.45]) (adj. R2 = 0.28). For MRPA versus no P. aeruginosa, risks were age (in 5-year increments) (1.17 [1.03, 1.33]), more prior admissions (1.40 [1.08, 1.81]), and more days in the intensive care unit (1.10 [1.03, 1.18]) (adj. R2 = 0.32). Other invasive devices (including mechanical ventilation) and previous antibiotic use (including carbapenems) were nonsignificant. MRPA mortality (31%) did not differ from that of MSPA (15%) when adjusted for time at risk (P = .15) but did from mortality without P. aeruginosa (9%) (P = .01 ). Median LOS and costs were greater for MRPA patients versus MSPA patients and patients without P. aeruginosa: 30 days versus 16 and 10 (P < .01 ) and $88,425 versus $28,620 and $22,605 (P <.01).

Conclusions.

Although antibiotic use has been shown to promote resistance, our data found that prior antibiotic use was not associated with MRPA acquisition. However, admission frequency and Foley catheters were, suggesting that infection control measures are essential to reducing MRPA transmission.

Clostridium difficile infection, a descriptive analysis of solid organ transplant recipients at a single center

Clostridium difficile is a bacterial enteric pathogen, which causes clinical disease among solid organ transplant (SOT) recipients. This large, single-center, retrospective study describes incidence, demographics, and impact of C. difficile infection (CDI) among adult SOT recipients, cardiac (n=5), lung (n=14), liver (n=9), renal (n=26), and multiorgan (n=9) patients transplanted and diagnosed with CDI (geneB PCR) between 9/2009 and 12/2012. The overall incidence of CDI in our population during the 40-month period of study was 4%. CDI incidence among cardiac, lung, liver, and renal transplant recipients was 1.9%, 7%, 2.7%, and 3.2%, respectively (P=0.03 between organ-types). Median time from transplant to CDI for all was 51 (14-249) days, with liver recipients having the shortest time to infection, median 36 (15-101) days, and lung recipients having a longer time to infection, median 136 (29-611) days. Antibiotic exposure within 3 months of CDI was evident in 45 of the 63 (71%) patients in this study, 80%, 79%, 100%, 58%, and 67% of cardiac, lung, liver, renal, and multiorgan transplant recipients, respectively. Most patients (83%) were hospitalized within the 3 months preceding CDI. Recipients were followed for a median time of 23 (16-31) months; at the time of last follow-up, 83% of allografts were functioning, and 86% of patients were alive. One death and 1 graft failure were causally related to CDI. CDI had an overall incidence of 4%; clinicians should have heightened awareness for CDI, especially among patients receiving antibiotics, with increased monitoring and aggressive management of CDI.

Novel antiseptic compound OPB-2045G shows potent bactericidal activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus both in vitro and in vivo: a pilot study in animals

There is a need for new compounds to effectively treat methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). The novel monobiguanide compound 1-(3,4-dichlorobenzyl)-5-octylbiguanide gluconate (OPB-2045G) has potential bactericidal activity. We sought to elucidate the potency of OPB-2045G bactericidal activity against MRSA and VRE compared to those of chlorhexidine digluconate (CHG) and povidone iodine (PVP-I). In vitro bactericidal activity was analysed using minimum bactericidal concentration (MBC) as the index. The in vivo bactericidal efficacy of OPB-2045G was examined by determining MRSA and VRE contamination of the normal dorsal skin of mice following removal of hair. After a 3 min treatment period, the MBC of OPB-2045G was lower than that of CHG and PVP-I against standard strains and clinical isolates. Additionally, in our in vivo mouse model, the in vivo bactericidal activity of 1.5 % OPB-2045G (a clinically relevant dose) was higher than that of 0.5 % CHG and equivalent to that of 10 % PVP-I against MRSA. Similarly, the in vivo bactericidal activity of OPB-2045G was higher than that of 0.5 % CHG and 10 % PVP-I against VRE. OPB-2045G showed more potent bactericidal activity against MRSA and VRE both in vitro and in vivo compared to CHG and PVP-I, indicating that OPB-2045G may provide better protection against health care-associated infections caused by these pathogens.

Characteristics of microbial drug resistance and its correlates in chronic diabetic foot ulcer infections

While virulence factors and the biofilm-forming capabilities of microbes are the key regulators of the wound healing process, the host immune response may also contribute in the events following wound closure or exacerbation of non-closure. We examined samples from diabetic and non-diabetic foot ulcers/wounds for microbial association and tested the microbes for their antibiotic susceptibility and ability to produce biofilms. A total of 1074 bacterial strains were obtained with staphylococci, Pseudomonas, Citrobacter and enterococci as major colonizers in diabetic samples. Though non-diabetic samples had a similar assemblage, the frequency of occurrence of different groups of bacteria was different. Gram-negative bacteria were found to be more prevalent in the diabetic wound environment while Gram-positive bacteria were predominant in non-diabetic ulcers. A higher frequency of monomicrobial infection was observed in samples from non-diabetic individuals when compared to samples from diabetic patients. The prevalence of different groups of bacteria varied when the samples were stratified according to age and sex of the individuals. Several multidrug-resistant strains were observed among the samples tested and most of these strains produced moderate to high levels of biofilms. The weakened immune response in diabetic individuals and synergism among pathogenic micro-organisms may be the critical factors that determine the delicate balance of the wound healing process.

Hand-hygiene compliance does not predict rates of resistant infections in critically ill surgical patients

BACKGROUND

Our institution had a major outbreak of multi-drug-resistant Acinetobacter (MDRA) in its general surgical and trauma intensive care units (ICUs) in 2011, requiring implementation of an aggressive infection-control response. We hypothesized that poor hand-hygiene compliance (HHC) may have contributed to the outbreak of MDRA. A response to the outbreak including aggressive environmental cleaning, cohorting, and increased hand hygiene compliance monitoring may have led to an increase in HHC after the outbreak and to a consequent decrease in the rates of infection by the nosocomial pathogens methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and Clostridium difficile.

METHODS

Hand-hygiene compliance, tracked in monthly audits by trained and anonymous observers, was abstracted from an infection control database. The incidences of nosocomial MRSA, VRE, and C. difficile were calculated from a separate prospectively collected data base for 6 mo before and 12 mo after the 2011 outbreak of MDRA in the institution's general surgical and trauma ICUs, and data collected prospectively from two unaffected ICUs (the thoracic surgical ICU and medical intensive care unit [MICU]). We created a composite endpoint of "any resistant pathogen," defined as MRSA, VRE, or C. difficile, and compared incidence rates over time, using the Wilcoxon signed rank test and Pearson product-moment correlation coefficient to measure the correlations among these rates.

RESULTS

Rates of HHC before and after the outbreak of MDRA were consistently high in both the general surgical (median rates: 100% before and 97.6% after the outbreak, p=0.93) and trauma ICUs (median rates: 90% before and 96.75% after the outbreak, p=0.14). In none of the ICUs included in the study did the rates of HHC increase in response to the outbreak of MDRA. The incidence of "any resistant pathogen" decreased in the general surgical ICU after the outbreak (from 6.7/1,000 patient-days before the outbreak to 2.7/1,000 patient-days after the outbreak, p=0.04), but this decrease did not correlate with HHC (trauma ICU: Pearson correlation [ρ]=-0.34, p=0.28; general surgical ICU: ρ=0.52, p=0.08).

CONCLUSIONS

The 2011 outbreak of MDRA at our institution occurred despite high rates of HHC. Notwithstanding stable rates of HHC, the rates of infection with MRSA, VRE and C. difficile decreased in the general surgical ICU after the outbreak. This suggests that infection control tactics other than HHC play a crucial role in preventing the transmission of nosocomial pathogens, especially when rates of HHC have been maximized.

Bringing them together: plasmid pMV158 rolling circle replication and conjugation under an evolutionary perspective

Rolling circle-replicating plasmids constitute a vast family that is particularly abundant in, but not exclusive of, Gram-positive bacteria. These plasmids are constructed as cassettes that harbor genes involved in replication and its control, mobilization, resistance determinants and one or two origins of lagging strand synthesis. Any given plasmid may contain all, some, or just only the replication cassette. We discuss here the family of the promiscuous streptococcal plasmid pMV158, with emphasis on its mobilization functions: the product of the mobM gene, prototype of the MOBV relaxase family, and its cognate origin of transfer, oriT. Amongst the subfamily of MOBV1 plasmids, three groups of oriT sequences, represented by plasmids pMV158, pT181, and p1414 were identified. In the same subfamily, we found four types of single-strand origins, namely ssoA, ssoU, ssoW, and ssoT. We found that plasmids of the rolling-circle Rep_2 family (to which pMV158 belongs) are more frequently found in Lactobacillales than in any other bacterial order, whereas Rep_1 initiators seemed to prefer hosts included in the Bacillales order. In parallel, MOBV1 relaxases associated with Rep_2 initiators tended to cluster separately from those linked to Rep_1 plasmids. The updated inventory of MOBV1 plasmids still contains exclusively mobilizable elements, since no genes associated with conjugative transfer (other than the relaxase) were detected. These plasmids proved to have a great plasticity at using a wide variety of conjugative apparatuses. The promiscuous recognition of non-cognate oriT sequences and the role of replication origins for lagging-strand origin in the host range of these plasmids are also discussed.