Risk factors for nosocomial infection and mortality in burn patients: 10 years of experience at a university hospital

Epidemiology and outcomes of bloodstream infections in 177 severe burn patients from an industrial disaster: a multicentre retrospective study

OBJECTIVES

To determine the characteristics of bloodstream infections (BSIs) and to evaluate the impact of BSIs on mortality in severe burn patients.

METHODS

A retrospective observational study was conducted in 20 tertiary hospitals. A total of 185 patients who experienced a massive dust explosion in eastern China were included.

RESULTS

After exclusion, 177 patients were analysed. The median total body surface area (TBSA) burned was 95% (interquartile range 85%-98%). Inhalation injuries occurred in 97.2%. The overall 90-day mortality was 35% (62/177). During the study period, 120 (67.8%) patients developed 253 episodes of BSI with 323 unique causative pathogens. Sixty-six episodes were polymicrobial infections. Catheter-related BSIs (CRBSIs) accounted for 41.5% of the episodes. Acinetobacter baumannii (19.5%), Klebsiella pneumoniae (13.9%) and Candida (12.7%) were the most common organisms. Antimicrobial resistance was found in 63.5% of the isolates, particularly in Gram-negative bacteria. Patients who developed BSIs had a greater illness severity at admission to the intensive care unit, and worse outcomes. After adjusting for demographics, severity of illness and treatment characteristics in a multivariate logistic model, there was a trend toward BSI increasing the risk of 90-day mortality (adjusted OR 3.4; 95% CI 0.9-12.9; p=0.069). In subgroup analyses, CRBSIs (adjusted OR 5.7; 95% CI 1.3-24.9; p=0.021 versus no BSI) and polymicrobial BSIs (adjusted OR 6.1; 95% CI 1.3-28.1; p=0.020 versus no BSI) had greater risk of 90-day mortality.

CONCLUSIONS

A strikingly high rate of BSIs was observed in severe burn patients. Gram-negative organisms and fungi were the leading causes. CRBSIs and polymicrobial BSIs were associated with high mortality.

Right first time!

Septic shock is still a lethal disease in intensive care units (ICU). The mortality can exceed 40% even with therapeutic management. The high mortality is clearly associated with the delay of appropriate antimicrobial therapy. Early diagnosis and identification of infectious source is the mainstay of optimal therapeutic management. On the other hand, source control and optimize antibiotic dosing according to pharmacokinetics (PK)/pharmacodynamics (PD) properties of antibiotics and organ dysfunction of patients are required to get the best clinical outcome.

Health care-associated infections in patients with head and neck cancer treated with chemotherapy and/or radiotherapy

BACKGROUND

The incidence of health care-associated infections in patients with head and neck cancer receiving chemotherapy and/or radiotherapy (RT) is unknown. This retrospective study investigated the most common pathogens and their antibiotic sensitivity/resistance patterns in patients with head and neck cancer.

METHODS

Infection rates in patients with head and neck cancer were analyzed over 2 periods (January 2005 to December 2009 and January 2010 to November 2012).

RESULTS

In the first period, 140 health care-associated infections were observed among 2288 admissions, mostly because of gram-negative pathogens affecting the respiratory tract. In the second period, 212 health care-associated infections were observed. An increase in antibiotic resistance was reported. Health care-associated infections were more frequent with: male sex, age <65 years, important comorbidities, smoking, proton pump inhibitors (PPIs), prophylaxis, and/or central venous catheter (CVC), locally advanced disease, and chemotherapy/RT, especially after the third week of treatment.

CONCLUSION

Health care-associated infections increased over time, with corresponding increases in gram-negative pathogens and resistant strains. Prevention and treatment protocols should be implemented in institutions treating patients with head and neck cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1009-E1013, 2016.

Long term mortality in burned children

Studies about risk factors for mortality in burn children are scarce and are even less in the follow up of this population across time. Usually, after complete event attendance, children are not follow-up as risk patients, burn injury affects all facets of life. Integration of professionals from different disciplines has enabled burn centers to develop collaborative methods of assessing the quality of care delivered to patients with burns. In this editorial we comment the paper of Duke et al. The authors highlight the importance of maintaining a long-term monitoring of children who suffered burns. The importance of this original study is to promote the reconsideration of clinical guides of long-term follow-up of burn patients.

Acinetobacter infections and outcomes at an academic medical center: a disease of long-term care

Background. Our study aims to describe the epidemiology, microbial resistance patterns, and clinical outcomes of Acinetobacter infections at an academic university hospital. This retrospective study analyzed all inpatient clinical isolates of Acinetobacter collected at an academic medical center over 4 years. The data were obtained from an Academic tertiary referral center between January 2008 and December 2011. All consecutive inpatients during the study period who had a clinical culture positive for Acinetobacter were included in the study. Patients without medical records available for review or less than 18 years of age were excluded.

Methods. Records were reviewed to determine source of isolation, risk factors for acquisition, drug resistance patterns, and clinical outcomes. Repetitive sequence-based polymerase chain reaction of selected banked isolates was used to determine patterns of clonal spread in and among institutions during periods of higher infection rates.

Results. Four hundred eighty-seven clinical isolates of Acinetobacter were found in 212 patients (in 252 admissions). Patients with Acinetobacter infections were frequently admitted from healthcare facilities (HCFs) (59%). One hundred eighty-three of 248 (76%) initial isolates tested were resistant to meropenem. One hundred ninety-eight of 249 (79.5%) initial isolates were multidrug resistant (MDR). Factors associated with mortality included bacteremia (odds ratio [OR] = 1.93, P = .024), concomitant steroid use (OR = 2.87, P < .001), admission from a HCF (OR = 6.34, P = .004), and chronic obstructive pulmonary disease (OR = 3.17, P < .001).

Conclusions. Acinetobacter isolates at our institution are frequently MDR and are more common among those who reside in HCFs. Our findings underline the need for new strategies to prevent and treat this pathogen, including stewardship efforts in long-term care settings.

Risk factors for nosocomial burn wound infection caused by multidrug resistant Acinetobacter baumannii

Acinetobacter baumannii infections in burn patients may lead to delays in wound healing, graft losses, and development of sepsis. Determining the risk factors for multidrug resistant A. baumannii (MDR-AB) infections is essential for infection control. In the present study, the authors aimed to evaluate risk factors for wound infections caused by A. baumannii in burn patients. The study was conducted at Dicle University Hospital Burn Center, from April 2011 to July 2012, to investigate the risk factors for MDR-AB infections. The data of both the case and control group patients and the result of wound cultures were recorded on a daily basis, on individual forms given for each patient, and analyzed. A total of 30 cases infected with MDR-AB, and 60 uninfected control patients, were included in the study. The mean age (±SD) was 7.7 ± 15.4 years in infected patients and 11.4 ± 16.5 years in uninfected patients. The mean total burn surface area was 13.5 ± 10.9% in uninfected patients and 34.7 ± 16.2% in infected patients. The mean total burn surface area, the abbreviated burn severity index, acute physiological and chronic health evaluation II score, day of admission to hospital, length of hospital stay, first excision day, prior usage of third-generation cephalosporins, and stay in intensive care unit of the infected patients were significantly higher (P < .001) than those of patients without infection. Univariate analysis found that high acute physiological and chronic health evaluation II score, first excision time of wound, invasive device usage, admission day to hospital, and prior usage of broad-spectrum antibiotics were risk factors for nosocomial infections. This study showed that multiple factors contribute to multidrug resistance in A. baumannii. A combination of an early diagnosis of wound infections, appropriate antimicrobial treatments, surgical debridement, and early wound closure may be effective in the management.

Burn mouse models

Severe thermal injury induces immunosuppression, involving all parts of the immune system, especially when large fractions of the total body surface area are affected. An animal model was established to characterize the burn-induced immunosuppression. In our novel mouse model a 6 % third-degree burn injury was induced with a hot-air blower. The third-degree burn was confirmed histologically. At 48 h, a decline in the concentration of peripheral blood leucocytes was observed in the group of mice with burn wound. The reduction was ascribed to the decline in concentration of polymorphonuclear neutrophil leucocytes and monocytes. When infecting the skin with Pseudomonas aeruginosa, a dissemination of bacteria was observed only in the burn wound group. Histological characterization of the skin showed an increased polymorphonuclear neutrophil granulocytes dominated inflammation in the group of mice with infected burn wound compared with the burn wound only group. The burn mouse model resembles the clinical situation and provides an opportunity to examine or develop new strategies like new antibiotics and immune therapy, in handling burn wound victims much.

Genital burns in the national burn repository: incidence, etiology, and impact on morbidity and mortality

OBJECTIVE

To better characterize national genital burns (GBs) characteristics using a large burn registry. We hypothesized that mortality and morbidity will be higher in patients with GBs.

METHODS

The National Burn Repository, a large North American registry of hospitalized burn patients, was queried for patients with GB. Burn characteristics and mechanism, demographics, mortality, and surgical interventions were retrieved. Outcomes of interest were mortality, hospital-acquired infection (HAI), and surgical intervention on the genitalia. Adjusted odds ratios (aOR) for outcomes were determined with binomial logistic regression controlling for age, total burn surface area, race, length of stay, gender, and inhalation injury presence.

RESULTS

GBs were present in 1245 cases of 71,895 burns (1.7%). Patients with GB had significantly greater average total burn surface area, length of stay, and mortality. In patients with GB, surgery of the genitalia was infrequent (10.4%), with the aOR of receiving surgery higher among men (aOR 2.7, P <.001) and those with third-degree burns (aOR 3.1, P <.002). Presence of a GB increased the odds of HAI (aOR 3.0, P <.0001) and urinary tract infections (aOR 3.4, P <.0001). GB was also an independent predictor of mortality (aOR 1.54) even after adjusting for the increased HAI risk.

CONCLUSION

GBs are rare but associated with higher HAI rates and higher mortality after adjusting for well-established mortality risk factors. Although a cause and effect relationship cannot be established using these registry data, we believe this study suggests the need for special management considerations in GB cases to improve overall outcomes.

LTQ-XL mass spectrometry proteome analysis expands the Pseudomonas aeruginosa AmpR regulon to include cyclic di-GMP phosphodiesterases and phosphoproteins, and identifies novel open reading frames

Pseudomonas aeruginosa is well known for its antibiotic resistance and intricate regulatory network, contributing to its success as an opportunistic pathogen. This study is an extension of our transcriptomic analyses (microarray and RNA-Seq) to understand the global changes in PAO1 upon deleting a gene encoding a transcriptional regulator AmpR, in the presence and absence of β-lactam antibiotic. This study was performed under identical conditions to explore the proteome profile of the ampR deletion mutant (PAOΔampR) using LTQ-XL mass spectrometry. The proteomic data identified ~53% of total PAO1 proteins and expanded the master regulatory role of AmpR in determining antibiotic resistance and multiple virulence phenotypes in P. aeruginosa. AmpR proteome analysis identified 853 AmpR-dependent proteins, which include 102 transcriptional regulators and 21 two-component system proteins. AmpR also regulates cyclic di-GMP phosphodiesterases (PA4367, PA4969, PA4781) possibly affecting major virulence systems. Phosphoproteome analysis also suggests a significant role for AmpR in Ser, Thr and Tyr phosphorylation. These novel mechanisms of gene regulation were previously not associated with AmpR. The proteome analysis also identified many unannotated and misannotated ORFs in the P. aeruginosa genome. Thus, our data sheds light on important virulence regulatory pathways that can potentially be exploited to deal with P. aeruginosa infections.

BIOLOGICAL SIGNIFICANCE

The AmpR proteome data not only confirmed the role of AmpR in virulence and resistance to multiple antibiotics, but also expanded the perimeter of AmpR regulon. The data presented here points to the role of AmpR in regulating cyclic di-GMP levels and phosphorylation of Ser, Thr and Tyr, adding another dimension to the regulatory functions of AmpR. We also identify some previously unannotated/misannotated ORFs in the P. aeruginosa genome, indicating the limitations of existing ORF analyses software. This study will contribute towards understanding complex genetic organization of P. aeruginosa. Whole genome proteomic picture of regulators at higher nodal positions in the regulatory network will not only help us link various virulence phenotypes but also design novel therapeutic strategies.

Antibiotic prophylaxis for preventing burn wound infection

BACKGROUND

Infection of burn wounds is a serious problem because it can delay healing, increase scarring and invasive infection may result in the death of the patient. Antibiotic prophylaxis is one of several interventions that may prevent burn wound infection and protect the burned patient from invasive infections.

OBJECTIVES

To assess the effects of antibiotic prophylaxis on rates of burn wound infection.

SEARCH METHODS

In January 2013 we searched the Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid MEDLINE - In-Process & Other Non-Indexed Citations (2013); Ovid EMBASE; EBSCO CINAHL and reference lists of relevant articles. There were no restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that evaluated the efficacy and safety of antibiotic prophylaxis for the prevention of BWI. Quasi-randomised studies were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed the risk of bias, and extracted relevant data. Risk ratio (RR) and mean difference (MD) were estimated for dichotomous data and continuous data, respectively. When sufficient numbers of comparable RCTs were available, trials were pooled in a meta-analysis to estimate the combined effect.

MAIN RESULTS

This review includes 36 RCTs (2117 participants); twenty six (72%) evaluated topical antibiotics, seven evaluated systemic antibiotics (four of these administered the antibiotic perioperatively and three administered upon hospital admission or during routine treatment), two evaluated prophylaxis with non absorbable antibiotics, and one evaluated local antibiotics administered via the airway.The 11 trials (645 participants) that evaluated topical prophylaxis with silver sulfadiazine were pooled in a meta analysis. There was a statistically significant increase in burn wound infection associated with silver sulfadiazine compared with dressings/skin substitute (OR = 1.87; 95% CI: 1.09 to 3.19, I(2) = 0%). These trials were at high, or unclear, risk of bias. Silver sulfadiazine was also associated with significantly longer length of hospital stay compared with dressings/skin substitute (MD = 2.11 days; 95% CI: 1.93 to 2.28).Systemic antibiotic prophylaxis in non-surgical patients was evaluated in three trials (119 participants) and there was no evidence of an effect on rates of burn wound infection. Systemic antibiotics (trimethoprim-sulfamethoxazole) were associated with a significant reduction in pneumonia (only one trial, 40 participants) (RR = 0.18; 95% CI: 0.05 to 0.72) but not sepsis (two trials 59 participants) (RR = 0.43; 95% CI: 0.12 to 1.61).Perioperative systemic antibiotic prophylaxis had no effect on any of the outcomes of this review.Selective decontamination of the digestive tract with non-absorbable antibiotics had no significant effect on rates of all types of infection (2 trials, 140 participants). Moreover, there was a statistically significant increase in rates of MRSA associated with use of non-absorbable antibiotics plus cefotaxime compared with placebo (RR = 2.22; 95% CI: 1.21 to 4.07).There was no evidence of a difference in mortality or rates of sepsis with local airway antibiotic prophylaxis compared with placebo (only one trial, 30 participants).

AUTHORS' CONCLUSIONS

The conclusions we are able to draw regarding the effects of prophylactic antibiotics in people with burns are limited by the volume and quality of the existing research (largely small numbers of small studies at unclear or high risk of bias for each comparison). The largest volume of evidence suggests that topical silver sulfadiazine is associated with a significant increase in rates of burn wound infection and increased length of hospital stay compared with dressings or skin substitutes; this evidence is at unclear or high risk of bias. Currently the effects of other forms of antibiotic prophylaxis on burn wound infection are unclear. One small study reported a reduction in incidence of pneumonia associated with a specific systematic antibiotic regimen.

Ex vivo transcriptional profiling reveals a common set of genes important for the adaptation of Pseudomonas aeruginosa to chronically infected host sites

The opportunistic bacterium Pseudomonas aeruginosa is a major nosocomial pathogen causing both devastating acute and chronic persistent infections. During the course of an infection, P.  aeruginosa rapidly adapts to the specific conditions within the host. In the present study, we aimed at the identification of genes that are highly expressed during biofilm infections such as in chronically infected lungs of patients with cystic fibrosis (CF), burn wounds and subcutaneous mouse tumours. We found a common subset of differentially regulated genes in all three in vivo habitats and evaluated whether their inactivation impacts on the bacterial capability to form biofilms in vitro and to establish biofilm-associated infections in a murine model. Additive effects on biofilm formation and host colonization were discovered by the combined inactivation of several highly expressed genes. However, even combined inactivation was not sufficient to abolish the establishment of an infection completely. These findings can be interpreted as evidence that either redundant traits encode functions that are essential for in vivo survival and chronic biofilm infections and/or bacterial adaptation is considerably achieved independently of transcription levels. Supplemental screens, will have to be applied in order to identify the minimal set of key genes essential for the establishment of chronic infectious diseases.