Showing papers by "Clinton K. Murray published in 2013"
TL;DR: In patients with relapsing infections, the majority of serial isolates recovered from these individuals were observed to be strong biofilm producers in vitro, and strains from patients with persistent infections are positive for biofilm formation.
Abstract: Biofilm formation is a major virulence factor contributing to the chronicity of infections. To date few studies have evaluated biofilm formation in infecting isolates of patients including both Gram-positive and Gram-negative multidrug-resistant (MDR) species in the context of numerous types of infectious syndromes. Herein, we investigated the biofilm forming capacity in a large collection of single patient infecting isolates and compared the relationship between biofilm formation to various strain characteristics. The biofilm-forming capacity of 205 randomly sampled clinical isolates from patients, collected from various anatomical sites, admitted for treatment at Brooke Army Medical Center (BAMC) from 2004–2011, including methicillin-resistant/methicillin susceptible Staphylococcus aureus (MRSA/MSSA) (n=23), Acinetobacter baumannii (n=53), Pseudomonas aeruginosa (n=36), Klebsiella pneumoniae (n=54), and Escherichia coli (n=39), were evaluated for biofilm formation using the high-throughput microtiter plate assay and scanning electron microscopy (SEM). Relationships between biofilm formation to clonal type, site of isolate collection, and MDR phenotype were evaluated. Furthermore, in patients with relapsing infections, serial strains were assessed for their ability to form biofilms in vitro. Of the 205 clinical isolates tested, 126 strains (61.4%) were observed to form biofilms in vitro at levels greater than or equal to the Staphylococcus epidermidis, positive biofilm producing strain, with P. aeruginosa and S. aureus having the greatest number of biofilm producing strains. Biofilm formation was significantly associated with specific clonal types, the site of isolate collection, and strains positive for biofilm formation were more frequently observed to be MDR. In patients with relapsing infections, the majority of serial isolates recovered from these individuals were observed to be strong biofilm producers in vitro. This study is the first to evaluate biofilm formation in a large collection of infecting clinical isolates representing diverse types of infections. Our results demonstrate: (1) biofilm formation is a heterogeneous property amongst clinical strains which is associated with certain clonal types, (2) biofilm forming strains are more frequently isolated from non-fluid tissues, in particular bone and soft tissues, (3) MDR pathogens are more often biofilm formers, and (4) strains from patients with persistent infections are positive for biofilm formation.
308 citations
TL;DR: The efficacy of blue light at 415 nm for the treatment of acute, potentially lethal Pseudomonas aeruginosa burn infections in mice is demonstrated and it is suggested that blue light therapy might offer an effective and safe alternative to conventional antimicrobial therapy for P. aerug inosa burns.
Abstract: Blue light has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. However, the use of blue light for wound infections has not been established yet. In this study, we demonstrated the efficacy of blue light at 415 nm for the treatment of acute, potentially lethal Pseudomonas aeruginosa burn infections in mice. Our in vitro studies demonstrated that the inactivation rate of P. aeruginosa cells by blue light was approximately 35-fold higher than that of keratinocytes (P = 0.0014). Transmission electron microscopy revealed blue light-mediated intracellular damage to P. aeruginosa cells. Fluorescence spectroscopy suggested that coproporphyrin III and/or uroporphyrin III are possibly the intracellular photosensitive chromophores associated with the blue light inactivation of P. aeruginosa. In vivo studies using an in vivo bioluminescence imaging technique and an area-under-the-bioluminescence-time-curve (AUBC) analysis showed that a single exposure of blue light at 55.8 J/cm(2), applied 30 min after bacterial inoculation to the infected mouse burns, reduced the AUBC by approximately 100-fold in comparison with untreated and infected mouse burns (P < 0.0001). Histological analyses and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assays indicated no significant damage in the mouse skin exposed to blue light at the effective antimicrobial dose. Survival analyses revealed that blue light increased the survival rate of the infected mice from 18.2% to 100% (P < 0.0001). In conclusion, blue light therapy might offer an effective and safe alternative to conventional antimicrobial therapy for P. aeruginosa burn infections.
195 citations
TL;DR: There exists a therapeutic window of blue light for bacterial infections where bacteria are selectively inactivated by blue light while host tissue cells are preserved, and blue light therapy has the potential to rapidly reduce the bacterial load in SSTI.
Abstract: Background and objective: Bacterial skin and soft tissue infections (SSTI) affect millions of individuals annually in the United States. Treatment of SSTI has been significantly complicated by the increasing emergence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strains. The objective of this study was to demonstrate the efficacy of blue light (415±10 nm) therapy for eliminating CA-MRSA infections in skin abrasions of mice. Methods: The susceptibilities of a CA-MRSA strain (USA300LAC) and human keratinocytes (HaCaT) to blue light inactivation were compared by in vitro culture studies. A mouse model of skin abrasion infection was developed using bioluminescent USA300LAC::lux. Blue light was delivered to the infected mouse skin abrasions at 30 min (acute) and 24 h (established) after the bacterial inoculation. Bioluminescence imaging was used to monitor in real time the extent of infection in mice. Results: USA300LAC was much more susceptible to blue light inactivatio...
92 citations
TL;DR: Healthy US- and Afghanistan-based military personnel have community onset-MDR E. coli colonization, with Afghanistan- based personnel showing a 5.5-fold higher prevalence than healthy US-based personnel.
Abstract: Background
The US military has seen steady increases in multidrug-resistant (MDR) gram-negative bacteria (GNB) infections in casualties from Iraq and Afghanistan. This study evaluates the prevalence of MDR GNB colonization in US military personnel.
56 citations
01 Aug 2013
TL;DR: Annual rates of MDR GNB colonization were not significantly different over the three-year period, and assessment of predictive factors for MDRGNB colonization and the relationship between colonization and infection was ongoing.
Abstract: In response to the high rates of colonization and infection by multidrug-resistant gram-negative bacilli (MDR GNB), many military treatment facilities (MTFs) have implemented additional infection control practices, such as active surveillance cultures for asymptomatic colonization. Results of surveillance cultures (June 2009 - May 2012) collected from patients at Landstuhl Regional Medical Center (Landstuhl RMC), Germany, and three U.S. MTFs were analyzed to evaluate trends in MDR GNB colonization over time and across facilities. At Landstuhl RMC, 6.6 percent of patients were colonized on admission with MDR GNB compared to 12.4 percent of patients admitted to the participating U.S. MTFs. Escherichia coli was the predominant organism, representing 82.4 percent of MDR isolates at Landstuhl RMC and 67.1 to 83.3 percent at U.S. MTFs. Other common MDR GNB included Acinetobacter calcoaceticus-baumannii complex and Klebsiella pneumoniae. Although Pseudomonas aeruginosa was often isolated from the surveillance cultures, it was never multidrug-resistant. Annual rates of MDR GNB colonization were not significantly different over the three-year period. Ongoing research includes assessment of predictive factors for MDR GNB colonization and the relationship between colonization and infection.
48 citations
TL;DR: There was overall evidence of dose-dependent cytotoxicity of the various topical agents against the various cell lines tested, but there did not seem to be increased cell death with continued exposure to the agents over time.
Abstract: : Objectives: Posttraumatic invasive fungal infections threaten critically injured combat related injuries and require a combination of extensive surgery and systemic antifungal therapy, along with topical antimicro bials used adjunctively to control the infection. We evaluated the in vitro activity of topical agents in varying combinations and concentrations against molds from patients that were responsible for wound invasive fungal infections and the topical agents toxicity to human cells. Methods: Mafenide acetate solutions (2.5%, 5%, and 7.5%), amphotericin B solutions (2 mg/mL, 2 mg/mL, and 20 mg/mL), SMAT (5% mafenide acetate in combination with 2 mg/mL, 2 mg/mL, and 20 mg/mL amphotericin B), and Dakin s solutions (buffered sodium hypochlorite) (0.5%, 0.25%, and 0.125% and 10 fold serial dilutions of 0.25% 0.00000025%) were evaluated for antifungal activity against 4 molds using a time kill assay using standard conidial suspensions of 5 104 colony forming units per milliliter. To assess cellular toxicity, confluent monolayers of human keratinocytes, dermal fibroblasts, and osteoblasts were exposed to these topical agents. Based upon efficacy and toxicity ratios, an additional 10 molds were screened with selected concentrations of the topical agents for antifungal activity and toxicity. Results: All the topical agents seemed to have a dose dependent killing with only mafenide acetate showing time killing associated with prolonged contact. There was overall evidence of dose dependent cytotoxicity of the various topical agents against the various cell lines tested, but there did not seem to be increased cell death with continued exposure to the agents over time. Dakin s solution exhibited dose dependent toxicity and efficacy with 0.00025% appearing to optimize those parameters. Conclusions: Mafenide acetate and amphotericin B did not seem to persistently meet the toxicity and efficacy balance as consistently as Dakin s solution.
42 citations
TL;DR: MRSA and MSSA colonization of military personnel was not associated with deployment status or doxycycline exposure, and higher S. aureus oropharynx colonization rates were observed and may warrant changes in decolonization practices.
Abstract: Staphylococcus aureus [methicillin-resistant and methicillin-susceptible (MRSA/MSSA)] is a leading cause of infections in military personnel, but there are limited data regarding baseline colonization of individuals while deployed. We conducted a pilot study to screen non-deployed and deployed healthy military service members for MRSA/MSSA colonization at various anatomic sites and assessed isolates for molecular differences. Colonization point-prevalence of 101 military personnel in the US and 100 in Afghanistan was determined by swabbing 7 anatomic sites. US-based individuals had received no antibiotics within 30 days, and Afghanistan-deployed personnel were taking doxycycline for malaria prophylaxis. Isolates underwent identification and testing for antimicrobial resistance, virulence factors, and pulsed-field type (PFT). 4 individuals in the US (4 isolates- 3 oropharynx, 1 perirectal) and 4 in Afghanistan (6 isolates- 2 oropharynx, 2 nare, 1 hand, 1 foot) were colonized with MRSA. Among US-based personnel, 3 had USA300 (1 PVL+) and 1 USA700. Among Afghanistan-based personnel, 1 had USA300 (PVL+), 1 USA800 and 2 USA1000. MSSA was present in 40 (71 isolates-25 oropharynx, 15 nare) of the US-based and 32 (65 isolates- 16 oropharynx, 24 nare) of the Afghanistan-based individuals. 56 (79%) US and 41(63%) Afghanistan-based individuals had MSSA isolates recovered from extra-nare sites. The most common MSSA PFTs were USA200 (9 isolates) in the US and USA800 (7 isolates) in Afghanistan. MRSA/MSSA isolates were susceptible to doxycycline in all but 3 personnel (1 US, 2 Afghanistan; all were MSSA isolates that carried tetM). MRSA and MSSA colonization of military personnel was not associated with deployment status or doxycycline exposure. Higher S. aureus oropharynx colonization rates were observed and may warrant changes in decolonization practices.
31 citations
TL;DR: Log peak CK was found to be correlated with any stage of acute kidney injury (AKI), and each 10-fold increase was associated with a 70% increase in the odds of AKI, and more than a 100% increases in the chances of moderate to severe AKI and mortality in patients with burn injury.
Abstract: The contribution of rhabdomyolysis to acute kidney injury (AKI) in the context of burn injury is poorly studied. We sought to determine the impact of rhabdomyolysis on AKI (defined by the AKI Network classification), renal replacement therapy (RRT), and death. Patients admitted to the burn unit at our institution were examined. Information on sex, age, presence of inhalation injury, electrical burn, percentage TBSA burned, percentage of full-thickness burns, Injury Severity Score, and peak creatine kinase (CK) were recorded. These variables were examined via multivariate logistic regression analysis against AKI Network stage, RRT, and death. Of 1973 consecutive admissions meeting the inclusion criteria, 525 met our eligibility criteria. Log peak CK was found to be correlated with any stage of AKI (odds ratio [OR], 1.71; 95% confidence interval [CI], 1.36-2.16; P < .0001), moderate to severe AKI (OR, 2.09; 95% CI, 1.40-3.11; P = .0003), need for RRT (OR, 1.67; 95% CI, 1.16-2.40; P = .0057), and mortality (OR, 1.49; 95% CI, 1.01-2.20; P = .0441), after adjustment. Each 10-fold increase in peak CK was associated with a 70% increase in the odds of AKI, more than a 100% increase in the odds of moderate to severe AKI, a nearly 70% increase in the odds of RRT, and an almost 50% increase in the odds of mortality in patients with burn injury.
25 citations
TL;DR: The overall 3% MRSA colonization rate is consistent with historical reports, but the oropharynx-only colonization supports more recent findings, and the use of deodorant/anti-perspirant invalidated axillary PCR samples, limiting its utility.
Abstract: Background: Methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus colonization is associated with increased rates of infection. Rapid and reliable detection methods are needed to identify colonization of nares and extra-nare sites, particularly given recent reports of oropharynx-only colonization. Detection methods for MRSA/MSSA colonization include culture, PCR, and novel methods such as PCR/electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). Methods: We evaluated 101 healthy military members for S. aureus colonization in the nares, oropharynx, axilla, and groin, using CHROMagar S. aureus medium and Xpert SA Nasal Complete PCR for MRSA/MSSA detection. The same subjects were screened in the nares, oropharynx, and groin using PCR/ESI-TOF-MS. Results: By culture, 3 subjects were MRSA-colonized (all oropharynx) and 34 subjects were MSSA-colonized (all 4 sites). PCR detected oropharyngeal MRSA in 2 subjects, which correlated with culture findings. By ...
19 citations
TL;DR: The United States introduced human T‐lymphotropic virus Type I (HTLV‐I) screening of blood donors in 1988 and all recipients of blood collected in combat are tested according to policy soon after and at 3, 6, and 12 months after transfusion.
19 citations
TL;DR: Positive BG and GM fungal screening assays are not associated with FWI/FWC, or with species of fungus when FWC/FWI is present, and false positives are common and associated with higher TBSA burns.
TL;DR: A total of 102 methicillin-resistant Staphylococcus aureus isolates collected from 50 injured service members at U.S. military treatment facilities were analyzed for the conventional mecA gene and mecC homologue by using standard PCR-based methods.
Abstract: A total of 102 methicillin-resistant Staphylococcus aureus (MRSA) isolates collected from 50 injured service members (June 2009 to December 2011) at U.S. military treatment facilities were analyzed for the conventional mecA gene and mecC homologue by using standard PCR-based methods. The prevalence of the mecC homologue was zero.
TL;DR: Whether statin exposure at physiologic concentrations enhances activity of selected antimicrobials against Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli is examined.
Abstract: Epidemiologic evidence suggests a beneficial effect of HMG-CoA reductase inhibitors (statins) in sepsis, and in-vitro data exist for antimicrobial activity of statins against some bacteria and fungi. We examined whether statin exposure at physiologic concentrations enhances activity of selected antimicrobials against Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli. Broth microdilution was performed with and without dose-ranging concentrations of lovastatin, fluvastatin, atorvastatin, pravastatin and simvastatin. No effects on antimicrobial activity were demonstrated.
TL;DR: CHROMagar Acinetobacter with the addition of the CR102 supplement at 2.5 ml/l and 5ml/l is highly sensitive and specific for the detection of imipenem-resistant ABC, and may be useful for the rapid detection of imitation resistance in clinical samples.
Abstract: Background: Acinetobacter baumannii–calcoaceticus complex (ABC) isolates are often multidrug-resistant, including to carbapenems Chromogenic media can facilitate the rapid detection of Gram-negative bacteria, often with the addition of supplements to a base chromogenic medium to detect resistance We examined various combinations of available media to detect imipenem resistance among 107 ABC clinical isolates Methods: CHROMagar Orientation, CHROMagar KPC, and CHROMagar Acinetobacter, by itself, with Acinetobacter supplement, with KPC supplement, or CHROMagar Acinetobacter with increasing concentrations (1, 25, and 5 ml/l) of a new CR102 supplement, were examined Results: Sensitivity for the detection of isolates was high (> 98%) for all formulations Specificity was high for CHROMagar Acinetobacter with 25 ml/l and 5 ml/l of the CR102 supplement, at 953% and 977%, respectively, with positive predictive values of 97% and 985% Negative predictive values of these 2 formulations were 100% Co
TL;DR: This case presents a healthy soldier with the first reported case of Pseudomonas fluorescens septic sacroiliitis and shows the early efficacy of oral antibiotics.
Abstract: Septic sacroiliitis is an uncommon infection of immunocompetent patients, typically caused by gram-positive bacteria, with fewer gram-negative cases, and only 5% attributed to Pseudomonas species. We present a healthy soldier with the first reported case of Pseudomonas fluorescens septic sacroiliitis and discuss unique diagnostic and management issues. Because of its rare incidence and nonspecific presentation, septic sacroiliitis is often unrecognized, and its diagnosis is often delayed. Increased awareness of septic sacroiliitis as a potential disease process in the differential diagnosis of troops presenting with a combination of fever, low-back pain, and weight-bearing difficulty is important. As the young age and trauma exposure of the military population represent a prime demographic for this often unrecognized infection, delayed diagnosis can negatively impact a soldier's military readiness. P. fluorescens is itself a rare pathogen and often misidentified in the laboratory. Enhanced microbi...
TL;DR: The characteristics of occupational exposures in this deployed environment were comparable to those of US-based hospitals, and standard practices used to reduce occupational exposures should continue to be prioritized in the deployed setting.
Abstract: Objective. Occupational exposures to blood and other bodily fluids occur in approximately 5 per 100 persons every year in US hospitals. Since the provision of health care in the deployed environment poses unique challenges to hospital personnel, it is important to characterize the rates of occupational exposures and understand the prevalence of blood-borne pathogens (BBPs) in host nations.Methods. A retrospective review of public health and laboratory records at a US military trauma center in Afghanistan from October 1, 2010, to March 31, 2012.Results. A total of 65 occupational exposures were reported, including 47 (72%) percutaneous and 18 (28%) mucocutaneous, with a yearly rate of 8.6 exposures per 100 persons. During 6-month deployment cycles, the majority of exposures (46.2%) occurred in the first 2 months after arrival in Afghanistan. Physicians reported the most exposures (26%), and the operating room (48%) was the most common hospital location. The prevalence of hepatitis B and hepatitis C among l...
TL;DR: It does not appear that hemostatic field dressings are contaminated, even after subjected to field conditions, and further research is needed to identify inoculation sources of fungi and mycobacteria, which cause infections.
Abstract: Infectious complications have a major impact on wounded warriors. Pathogens causing infections include multidrug-resistant bacteria, fungi, and mycobacteria. The potential sources for these pathogens include nosocomial transmission, the environment (e.g., dirt), or the patients (skin flora) themselves. The purpose of this pilot study was to explore the possibility that hemostatic field dressings might act as an inoculation source of pathogens into wounds. To accomplish this, hemostatic field dressings were assessed for the presence of bacterial, fungal, or mycobacterial contamination. We evaluated two samples of QuikClot Combat Gauze and two samples of CELOX Gauze subjected to normal stresses associated with storage after receipt from the manufacturer. We then evaluated 16 samples of QuikClot Combat Gauze that were collected from personnel deployed in Afghanistan and had undergone routine mechanical stress. Samples underwent screening with Trypticase Soy Broth, blood agar plates, MacConkey agar pl...
TL;DR: The PFGE methodology studied showed excellent interlaboratory reproducibility, enabling standardization and data sharing between laboratories, and was effective in identifying misidentified reference strains.
Abstract: Leptospirosis may be caused by > 250 Leptospira serovars. Serovar classification is a complex task that most laboratories cannot perform. We assessed the interlaboratory reproducibility of a pulsed-field gel electrophoresis (PFGE) identification technique developed by the Centers for Disease Control and Prevention (CDC). Blinded exchange of 93 Leptospiraceae strains occurred between San Antonio Military Medical Center (SAMMC) and the CDC. PFGE was performed and gel images were analyzed and compared with patterns present in each laboratory's database (CDC database: > 800 strain patterns; SAMMC database: > 300 strain patterns). Overall, 93.7% (74 of 79) of strains present in each receiving laboratory's database were correctly identified. Five isolates were misidentified, and two isolates did not match serovar PFGE patterns in the receiving laboratory's database. Patterns for these seven isolates were identical between laboratories; four serovars represented misidentified reference strains. The PFGE methodology studied showed excellent interlaboratory reproducibility, enabling standardization and data sharing between laboratories.