Swab cultures for diagnosing wound infections: a literature review and clinical guideline

An open label, single-centric, post market clinical study to evaluate the safety and efficacy of a new antimicrobial wound dressing (VELVERT) as an adjuvant therapy in the treatment of venous leg ulcer

OBJECTIVES

An open label, single-centric, post market clinical study was undertaken to evaluate the safety and efficacy of a new antimicrobial wound dressing (VELVERT) as an adjuvant therapy in the treatment of venous leg ulcer (VLU).

METHODS

Patients with VLU of grade C-5 according to CEAP classification and above were evaluated using doppler ultra sound. The efficacy of new antimicrobial wound dressing (VELVERT) was assessed in terms of wound area reduction within a time frame of 60 days and surgeon questioners. Patients were evaluated for VELVERT safety and pain level on a scale of 0-10 Numeric Pain Chart. Presence of micro-organism load was monitored at regular time interval.

RESULTS

VELVERT treatment was effective as 71.43% reduction in the ulcer area was observed. After 60 days, a total of 9 (45%) patients had complete ulcer closure. A remarkable decrease in the severity of pain was observed with 11 (55%) patients expressing no pain at the EOT. Swab test showed negative result for micro-organism growth. No serious adverse events were observed during the trial.

CONCLUSION

The data indicates that VELVERT is an effective treatment for VLUs and showed the potential in the wound care of VLUs.

Using spatial frequency domain imaging to monitor a skin biopsy wound: a pilot study

Surgical wound infection is a global postoperative issue adding a significant clinical burden and increasing healthcare costs. Early detection and subsequent diagnosis of infection is vital for accurate, early, and effective treatments. In this paper, we report a pilot study exploring spatial frequency domain imaging (SFDI) to monitor, in-vivo, a biopsy wound in human skin. The reduced scattering coefficient, μ s ' , absorption coefficient, μ a and the oxygen saturation, StO 2, were measured using a SFDI system at 617 and 850 nm. We found the μ s ' was better capable of monitoring structural changes, possible pus within the wound, re-epithelialization, and collagen fiber remodeling, than with the eye alone. The μ a map is capable of revealing the total hemoglobin distribution in the wound area but was limited in some regions due to the scab covering. This case study indicates SFDI's potential for monitoring and quantifying the process of surgical wound healing and infection.

Selective decontamination of the digestive tract in a burns unit reduces the incidence of hospital-acquired infections: A retrospective before-and-after cohort study

OBJECTIVE

To evaluate the effect of selective decontamination of the digestive tract (SDD) on hospital-acquired infections (HAIs) in patients with acute burn injury requiring admission to a Burns Unit (BU).

DESIGN

Retrospective before-and-after cohort study, between January 2017 and June 2023. SDD was implemented in March 2019, dividing patients into two groups.

SETTING

Four-bed BU, in a referral University Hospital in Spain.

PATIENTS

All the patients admitted during the study period were eligible for analysis. Patients who died or were discharged within 48hours of admission, and patients with an estimated survival less than 10% not considered for full escalation of therapy were excluded.

INTERVENTION

SDD comprised the administration of a 4-day course of an intravenous antibiotic, and an oral suspension and oral topical paste of non-absorbable antibiotics during the stay in the BU.

MAIN VARIABLE OF INTEREST

Incidence of HAIs during the stay in the BU.

SECONDARY OUTCOMES

incidence of specific types of infections by site (bacteremia, pneumonia, skin and soft tissue infection) and microorganism (Gram-positive, Gram-negative, fungi), and safety endpoints.

RESULTS

We analyzed 72 patients: 27 did not receive SDD, and 45 received SDD. The number of patients who developed HAIs were 21 (77.8%) and 21 (46.7%) in the non-SDD and the SDD groups, respectively (p=0.009). The number of hospital-acquired infectious episodes were 2.52 (1.21-3.82) and 1.13 (0.54-1.73), respectively (p=0.029).

CONCLUSIONS

SDD was associated with a reduced incidence of bacterial HAIs and a decrease in the number of infectious episodes per patient.

Integrating Point-of-Care Bacterial Fluorescence Imaging-Guided Care with Continued Wound Measurement for Enhanced Wound Area Reduction Monitoring

AIM

This prospective observational study investigated wound area reduction (WAR) outcomes in a complex wound population composed of non-healing acute and chronic wounds. The relationship between bacterial autofluorescence signals and WAR was investigated. Area measurements were collected both manually and digitally, and both methods were compared for accuracy.

METHODS

Twenty-six participants with 27 wounds of varying etiologies were observed twice weekly for two weeks. Digital wound measurement, wound bacterial status assessment, and targeted debridement were performed through a point-of-care fluorescence imaging device (MolecuLight® i: X, MolecuLight Inc, Toronto, Canada). The wound area reduction (WAR) rate was calculated using baseline and last visit measurements. Statistical analyses, including t-tests, Fisher exact tests, the Wilcoxon signed rank test for method comparison, and ANOVA for bacterial subgroups, were applied as pertinent.

RESULTS

The overall average WAR was -3.80 cm2, or a decrease of 46.88% (manual measurement), and -2.62 cm2, or a 46.05% decrease (digital measurement via MolecuLight® device). There were no statistically significant differences between the WAR of acute and chronic wounds (p = 0.7877). A stepwise correlation between the WAR and bacterial status classification per fluorescence findings was observed, where persistent bacteria resulted in worse WAR outcomes. An overestimation of wound area by manual measurement was 23% on average.

CONCLUSION

Fluorescence imaging signals were linked to WAR outcome and could be considered predictive. Wounds exhibiting bacterial loads that persisted at the end of the study period had worse WAR outcomes, while those for which management was able to effectively remove them demonstrated greater WAR. Manual measurement of the wound area consistently overestimated wound size when compared to digital measurement. However, if performed by the same operator, the overestimation was uniform enough that the WAR was calculated to be close to accurate. Notwithstanding, single wound measurements are likely to result in overestimation.

Development of PVA Electrospun Nanofibers for Fabrication of Bacteriological Swabs

In recent years, the enormous demand for swabs for clinical use has promoted their relevance and, consequently, brought the environmental issues due to their single use and lack of biodegradability to the attention of the healthcare industry. Swabs consist of a stick that facilitates their easy handling and manoeuvrability even in complex districts and an absorbent tip designed to uptake and release biological samples. In this study, we focused on the fabrication of an innovative biodegradable poly(vinyl alcohol) (PVA) nanofiber swab tip using the electrospinning technique. The innovative swab tip obtained showed comparable uptake and release capacity of protein and bacterial species (Pseudomonas aeruginosa and Staphylococcus aureus) with those of the commercial foam-type swab. In this way, the obtained swab can be attractive and suitable to fit into this panorama due to its low-cost process, easy scalability, and good uptake and release capabilities.

Simultaneous Analysis of Bacterial and Fungal Communities in Oral Samples from Intubated Patients in Intensive Care Unit

Intubated patients in intensive care units (ICUs) too frequently contract ventilator-associated pneumonia or Candida infections. Oropharyngeal microbes are believed to play an important etiologic role. This study was undertaken to determine whether next-generation sequencing (NGS) can be used to simultaneously analyze bacterial and fungal communities. Buccal samples were collected from intubated ICU patients. Primers targeting the V1-V2 region of bacterial 16S rRNA and the internal transcribed spacer 2 (ITS2) region of fungal 18S rRNA were used. V1-V2, ITS2, or mixed V1-V2/ITS2 primers were used to prepare an NGS library. Bacterial and fungal relative abundances were comparable for V1-V2, ITS2, or mixed V1-V2/ITS2 primers, respectively. A standard microbial community was used to adjust the relative abundances to theoretical abundance, and NGS and RT-PCR-adjusted relative abundances showed a high correlation. Using mixed V1-V2/ITS2 primers, bacterial and fungal abundances were simultaneously determined. The constructed microbiome network revealed novel interkingdom and intrakingdom interactions, and the simultaneous detection of bacterial and fungal communities using mixed V1-V2/ITS2 primers enabled analysis across two kingdoms. This study provides a novel approach to simultaneously determining bacterial and fungal communities using mixed V1-V2/ITS2 primers.

The Role of Autoflorescence Imaging Device in the Evaluation of Bacteria Burden Control

MolecuLight i:X is a autofluorescence, portable device that allows an assessment of wound area, perimeter, width and length and an evaluation in real time of wound surface bacteria (>104 CFU/g). Primary objective of our study was to evaluate the reduction of bacterial load associated to 3 different therapeutic approaches: dressings and multicomponent bandages (Group1), sharp debridement, dressings and multicomponent bandages (Group 2), and 10 patients treated with zinc oxide bandage (Group 3). Secondary objective was NRS pain scale, Wound Bed Score (WBS) and Quality of Life (QoL) assessment. Despite the improvement of bacterial load, WBS, Qol and NRS was evident in all 3 groups, the analysis of our results demonstrates that the application of zinc oxide bandage, directly in contact with the wound bed and/or the perilesional skin, resulted in a higher improvement and a significant reduction of WBS and bacterial load. Fluorescence imaging can help the specialist in a more targeted assessment and management of infection. Sharp debridement and antiseptic dressings are classically used to reduced bacteria burden. Zinc oxide directly on the wound is an interesting cost-effective option to control different types of bacteria.

Comparison of bacteriologic culture results for skin wound swabs and skin wound biopsy specimens

OBJECTIVE

To compare bacteriologic culture results for superficial swab and tissue biopsy specimens obtained from dogs with open skin wounds.

ANIMALS

52 client-owned dogs.

PROCEDURES

For each dog, 1 wound underwent routine preparation prior to collection of 2 specimens, 1 by superficial swab (Levine) technique and 1 by tissue biopsy. Specimens were processed for bacteriologic culture. Two observers determined whether any detected difference in culture results for the 2 types of specimen would have resulted in differing treatment plans.

RESULTS

Culture results of swab and tissue biopsy specimens were identical in 11/52 (21.2%) cases. Tissue biopsy specimen and swab cultures yielded positive results for 44 (84.6%) and 40 (76.9%) wounds, respectively. With regard to mean recovery rates of bacteria from wounds with positive culture results, both the biopsy specimens and swabs yielded 3.4 bacterial species/wound. All wounds for which swab cultures yielded no growth also had negative culture results for biopsy specimens. Biopsy specimen and swab culture results were in agreement with regard to the most common bacteria cultured. In 7/52 (13%) wounds, the observers would have treated the patient differently on the basis of the results of the 2 cultures.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that culture of a swab collected by the Levine technique is an appropriate noninvasive alternative to culture of a tissue biopsy specimen. A negative result obtained from culture of a swab is likely to be reliable. Disagreement between the results of swab and tissue biopsy specimen cultures is likely of low clinical importance.

Change in granulation tissue coverage and bacteriological load using Low Cost Negative Pressure Wound Therapy in acute musculoskeletal wounds

BACKGROUND

Low cost Negative Pressure Wound Therapy (NPWT) dressings have been considered as an alternative to traditional daily dressings. There is scanty literature evaluating the change in the percentage area of wound covered by granulation tissue following application of low-cost NPWT. The change in the bacteriological flora following application of low-cost NPWT devices has also not been evaluated.

METHODS

Patients above the age of 18 years with acute musculoskeletal injuries of <3 weeks duration which underwent a surgical debridement and required subsequent wound coverage were included in the study. Area of the wound and the area covered by the granulation tissue as well as the bacteriological count were measured before and after application of NPWT. A low cost NPWT using wall mounted vacuum device was put on the patient giving a constant negative pressure of 125 mm of Hg for 2 days. The findings before and after application of NPWT were compared and analyzed using Wilcoxin Signed-rank test.

RESULTS

21 patients with mean age of 35.52±15.075 were included. The pre-NPWT granulation tissue area ranged from 122 mm² to 8483 mm² with a mean of 1648.38 mm² (SD = 1933.866). The post-NPWT granulation tissue area ranged from 234 mm² to 7847 mm² with a mean of 2364.48 mm² (SD = 1857.716). The mean increase in granulation tissue was 716.1 mm².The pre-NPWT wound area ranged from 422 mm² to 10847 mm² with a mean of 4009.62 mm² (SD = 3026.209). The post-NPWT wound area ranged from 326 mm² to 9143 mm² with a mean of 3410.33 mm² (SD = 2636.206). The mean reduction in wound size was 599.29 mm².The pre-NPWT bacteriological count ranged from 3000/ml to 130000000/ml with a mean of 12616761.90/ml (SD = 29664589.37). The post-NPWT bacteriological count ranged from 1000/ml to 380000000/ml with a mean of 26401523.81/ml. The mean increase in bacteriological count was 13784761.91/ml.

CONCLUSION

There was a statistically significant decrease in wound size (p = 0.001) and statistically significant increase in percentage area of granulation tissue coverage (p = 0.000) following low cost NPWT application. However there was no statistically significant increase in bacteriological clearance in these patients.

Biofilm and Equine Limb Wounds

In chronic wounds in humans, biofilm formation and wound chronicity are linked, as biofilms contribute to chronic inflammation and delayed healing. Biofilms are aggregates of bacteria, and living as biofilms is the default mode of bacterial life; within these aggregates, the bacteria are protected from both antimicrobial substances and the immune response of the host. In horses, delayed healing is more commonly seen in limb wounds than body wounds. Chronic inflammation and hypoxia are the main characteristics of delayed wound healing in equine limbs, and biofilms might also contribute to this healing pattern in horses. However, biofilm formation in equine wounds has been studied to a very limited degree. Biofilms have been detected in equine traumatic wounds, and recent experimental models have shown that biofilms protract the healing of equine limb wounds. Detection of biofilms within wounds necessitates advanced techniques that are not available in routine diagnostic yet. However, infections with biofilm should be suspected in equine limb wounds not healing as expected, as they are in human wounds. Treatment should be based on repeated debridement and application of topical antimicrobial therapy.

Rapid Detection of Pathogenic Bacteria by the Naked Eye

Escherichia coli O157:H7 and Staphylococcus aureus are common pathogens. Gram-negative bacteria, such as E. coli, contain high concentrations of endogenous peroxidases, whereas Gram-positive bacteria, such as S. aureus, possess abundant endogenous catalases. Colorless 3,5,3',5'-tetramethyl benzidine (TMB) changes to blue oxidized TMB in the presence of E. coli and a low concentration of H2O2 (e.g., ~11 mM) at pH of 3. Moreover, visible air bubbles containing oxygen are generated after S. aureus reacts with H2O2 at a high concentration (e.g., 180 mM) at pH of 3. A novel method for rapidly detecting the presence of bacteria on the surfaces of samples, on the basis of these two endogenous enzymatic reactions, was explored. Briefly, a cotton swab was used for collecting bacteria from the surfaces of samples, such as tomatoes and door handles, then two-step endogenous enzymatic reactions were carried out. In the first step, a cotton swab containing bacteria was immersed in a reagent comprising H2O2 (11.2 mM) and TMB for 25 min. In the second step, the swab was dipped further in H2O2 (180 mM) at pH 3 for 5 min. Results showed that the presence of Gram-negative bacteria, such as E. coli with a cell number of ≥ ~105, and Gram-positive bacteria, such as S. aureus with a cell number of ≥ ~106, can be visually confirmed according to the appearance of the blue color in the swab and the formation of air bubbles in the reagent solution, respectively, within ~30 min. To improve visual sensitivity, we dipped the swab carrying the bacteria in a vial containing a growth broth, incubated it for ~4 h, and carried out the two-stage reaction steps. Results showed that bluish swabs resulting from the presence of E. coli O157: H7 with initial cell numbers of ≥ ~34 were obtained, whereas air bubbles were visible in the samples containing S. aureus with initial cell numbers of ≥ ~8.5 × 103.

Treatment of moderate grade dog bite wounds using amoxicillin-clavulanic acid with and without enrofloxacin: a randomised non-inferiority trial

BACKGROUND

Dog-to-dog bite wounds are a common veterinary emergency presentation: despite this, there is insufficient information to guide veterinarians on appropriate empirical antimicrobial management.

OBJECTIVES

Investigate the effectiveness of amoxicillin-clavulanic acid with and without enrofloxacin in the treatment of moderate grade dog bite wounds (DBW). To describe common pathogens and their antimicrobial susceptibility patterns.

MATERIALS AND METHODS

In a single-centre parallel group pragmatic trial, 50 dogs presenting with moderate grade DBW were prospectively randomised to receive amoxicillin-clavulanic acid (group A) or amoxicillin-clavulanic acid and enrofloxacin (group B). Swabs were taken for culture and susceptibility testing at admission. Stabilisation, wound care and surgical debridement were performed at the discretion of admitting clinicians. The primary outcome was complication due to infection at 10 days, with Bayesian inference used to estimate the difference in proportions between treatment groups.

RESULTS

Of the 24 dogs in treatment group A, 1 required the addition of enrofloxacin at re-examination. None of the 26 dogs in group B required alteration of antimicrobial coverage. The difference in complication rate due to infection between treatment groups was 4.2%. Twenty-one different organisms were identified: Staphylococcus pseudintermedius, Neisseria spp., Pasteurella multocida and P. canis were the most common. Over 90% of gram-negative and gram-positive isolates were susceptible to amoxicillin-clavulanic acid. Ninety-six percent of gram-negative and 86% of gram-positive isolates were susceptible to enrofloxacin.

CONCLUSION AND CLINICAL SIGNIFICANCE

Amoxicillin-clavulanic acid is an appropriate empirical antimicrobial choice for moderate DBW in South East Queensland. Reduced empirical enrofloxacin use will promote antimicrobial stewardship and potentially antimicrobial resistance.

Guidelines for Point-of-Care Fluorescence Imaging for Detection of Wound Bacterial Burden Based on Delphi Consensus

Excessive levels of bacteria impede wound healing and can lead to infectious complications. Unfortunately, clinical signs and symptoms of elevated bacterial burden are often unreliable. As a result, point--of--care fluorescence imaging, used to detect critical bacterial burden in wounds, is becoming widely recognized and adopted by clinicians across the globe as an accepted and added component of wound assessment protocol. A Delphi method was employed to establish consensus guidelines describing fluorescence imaging use. A multidisciplinary panel of 32 wound experts (56% MD, 22% podiatrist, 12.5% nurses/nurse practitioners) representing multiple sites of service (e.g., hospital outpatient, inpatient, private office, long-term care) completed two rounds of online questionnaires. The Delphi included key topics, including competencies required to perform imaging, clinical indications for imaging (e.g., signs/symptoms present, procedures warranting imaging), frequency of imaging, and a clinical workflow algorithm. Describing their clinical experiences of imaging impact, >80% reported changes in treatment plans, 96% reported that imaging-informed treatment plans led to improved wound healing, 78% reported reduced rates of amputations, and 83% reported reduced rates of microbiological sampling. The guidelines provided here will help to standardize use of fluorescence imaging among wound care providers and enhance the quality of patient care.

Challenges in the management of chronic wound infections

OBJECTIVES

Chronic wound infections may delay the healing process and are responsible for a significant burden on healthcare systems. Since inappropriate management may commonly occur in the care of these patients, this review aims to provide a practical guide underlining actions to avoid in the management of chronic wound infections.

METHODS

We performed a systematic review of the literature available in PubMed in the last 10 years, identifying studies regarding the management of patients with chronic wound infections. A panel of experts discussed the potential malpractices in this area. A list of 'Don'ts', including the main actions to be avoided, was drawn up using the 'Choosing Wisely' methodology.

RESULTS

In this review, we proposed a list of actions to avoid for optimal management of patients with chronic wound infections. Adequate wound bed preparation and wound antisepsis should be combined, as the absence of one of them leads to delayed healing and a higher risk of wound complications. Moreover, avoiding inappropriate use of systemic antibiotics is an important point because of the risk of selection of multidrug-resistant organisms as well as antibiotic-related adverse events.

CONCLUSION

A multidisciplinary team of experts in different fields (surgeon, infectious disease expert, microbiologist, pharmacologist, geriatrician) is required for the optimal management of chronic wound infections. Implementation of this approach may be useful to improve the management of patients with chronic wound infections.

Diagnostics for Wound Infections

Significance: Infections can significantly delay the healing process in chronic wounds, placing an enormous economic burden on health care resources. Identification of infection biomarkers and imaging modalities to observe and quantify them has seen progress over the years. Recent Advances: Traditionally, clinicians determine the presence of infection through visual observation of wounds and confirm their diagnosis through wound culture. Many laboratory markers, including C-reactive protein, procalcitonin, presepsin, and bacterial protease activity, have been quantified to assist diagnosis of infection. Moreover, imaging modalities like plain radiography, computed tomography, magnetic resonance imaging, ultrasound imaging, spatial frequency domain imaging, thermography, autofluorescence imaging, and biosensors have emerged for real-time wound infection diagnosis and showed their unique advantages in deeper wound infection diagnosis. Critical Issues: While traditional diagnostic approaches provide valuable information, they are time-consuming and depend on clinicians' experiences. There is a need for noninvasive wound infection diagnostics that are highly specific, rapid, and accurate, and do not require extensive training. Future Directions: While innovative diagnostics utilizing various imaging instrumentation are being developed, new biomarkers have been investigated as potential indicators for wound infection. Products may be developed to either qualitatively or quantitatively measure these biomarkers. This review summarizes and compares all available diagnostics for wound infection, including those currently used in clinics and still under development. This review could serve as a valuable resource for clinicians treating wound infections as well as patients and wound care providers who would like to be informed of the recent developments.

Characterization of staphylococci sampled from diabetic foot ulcer of Jordanian patients

AIMS

The aim of this study was to isolate and characterize staphylococcal isolates from diabetic foot ulcers (DFU) in Jordanian patients.

METHODS AND RESULTS

Selected aerobic pathogens recovered from DFU specimens and patients' nares with a focus on staphylococci were investigated. Antimicrobial susceptibilities and the prevalence of methicillin-resistant staphylococci (MRS) were determined. SCCmec types and toxigenic characteristics were analysed and spa typing was performed for methicillin-resistant Staphylococcus aureus (MRSA) isolates. The relationship between toxigenic characteristics of MRSA and the Wagner ulcer grading system was statistically analysed. A total number of 87 DFU patients were recruited for the study. The DFU cultures were polymicrobial. Members of the genus Staphylococcus were the most common among DFU-associated isolates found in 48·3% (n = 42) of all patients enrolled. Coagulase-negative staphylococci (CoNS) comprised 63·3% of staphylococci isolated from DFUs predominated by Staphylococcus epidermidis in both DFU (7·6%) and nares (39·2%). Staphylococcus aureus was isolated from DFUs and nares in 14·2 and 9·8%, respectively, while 93 and 70% of these isolates were MRSA. Most of MRSA carried SCCmec type IV (76·2%) while SCCmec elements were non-typeable in most methicillin resistant coagulase negative staphylococci (MR-CoNS) (61·9%). The most frequent MRSA spa type was t386 (23·8%). Most MRSA and MR-CoNS exhibited resistance towards aminoglycosides, fluoroquinolones and macrolides and susceptibility towards vancomycin, mupirocin and linezolid. No association was found between the possession of pvl, tst, sea and hlg toxins and Wagner ulcer grading system (P value >0·05).

CONCLUSIONS

This analysis of Jordanian DFU culture demonstrated its polymicrobial nature with predominance of Staphylococcus sp.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is the first of its type to assess the microbiology of DFU among Jordanian patients. The results will help in the appropriate application of antimicrobial chemotherapy in the management of DFU.

Consensus on the diagnosis and management of chronic leg ulcers - Brazilian Society of Dermatology

BACKGROUND

Chronic leg ulcers affect a large portion of the adult population and cause a significant social and economic impact, related to outpatient and hospital care, absence from work, social security expenses, and reduced quality of life. The correct diagnosis and therapeutic approach are essential for a favorable evolution.

OBJECTIVE

To gather the experience of Brazilian dermatologists, reviewing the specialized literature to prepare recommendations for the diagnosis and treatment of the main types of chronic leg ulcers.

METHODS

Seven specialists from six university centers with experience in chronic leg ulcers were appointed by the Brazilian Society of Dermatology to reach a consensus on the diagnosis and therapeutic management of these ulcers. Based on the adapted DELPHI methodology, relevant elements were considered in the diagnosis and treatment of chronic leg ulcers of the most common causes; then, the recent literature was analyzed using the best scientific evidence.

RESULTS

The following themes were defined as relevant for this consensus - the most prevalent differential etiological diagnoses of chronic leg ulcers (venous, arterial, neuropathic, and hypertensive ulcers), as well as the management of each one. It also included the topic of general principles for local management, common to chronic ulcers, regardless of the etiology.

CONCLUSION

This consensus addressed the main etiologies of chronic leg ulcers and their management based on scientific evidence to assist dermatologists and other health professionals and benefit the greatest number of patients with this condition.

Pretreatment aerobic bacterial swab cultures to predict infection in acute open traumatic wounds: A prospective clinical study of 64 dogs

OBJECTIVE

To determine the value of initial aerobic bacterial cultures of acute open traumatic wounds to predict bacterial species in wounds that become infected.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

Sixty-four dogs with naturally occurring acute cutaneous traumatic wounds (2017-2018).

METHODS

Initial swabs were taken from each wound prior to and after lavage and debridement for quantitative and qualitative aerobic bacterial culture. Cultures were repeated on wounds that displayed any clinical sign of infection within 14 days of presentation.

RESULTS

Fewer bacteria were cultured from postlavage than from prelavage swabs in 43 of 50 (86%) acute wounds. All primary clinicians prescribed β-lactam antibiotics to the dogs at initial presentation. All bacteria cultured from postlavage/debridement cultures at initial presentation were susceptible to the prophylactic antimicrobial prescribed. Postoperative infection was subsequently diagnosed in 14 of 64 (22%) dogs; 13 of these dogs had positive culture results. No correlation was detected between the results of initial wound cultures and the subsequent development of wound infection. Bacterial species present in the initial wound swab did not correlate with those subsequently cultured from infected tissues.

CONCLUSION

Results of pretreatment wound cultures from open traumatic wounds in dogs were not predictive of bacterial species subsequently recovered from infected wounds. The bacterial burden present in pretreatment wounds was not predictive of whether wounds would ultimately become infected after surgical management.

CLINICAL SIGNIFICANCE

Routine bacterial culturing of acute wounds is not likely to help predict subsequent wound infection, nor is it likely to accurately guide early selection of antimicrobials to treat wounds that become infected.

An evidence based narrative review on treatment of diabetic foot osteomyelitis

OBJECTIVE

The diagnosis of diabetic food infection is usually clinical, and its severity is related to location and depth of the lesion, and the presence of necrosis or gangrene. Osteomyelitis of the foot and ankle can be extremely debilitating, and, in the preantibiotic era acute staphylococcal osteomyelitis carried a mortality rate of 50%. The microbiology of diabetic foot osteomyelitis (DFO) is usually polymicrobial. Indeed, gram-negative and gram-positive bacilli can be identified using molecular techniques applied to bone biopsies compared to conventional techniques. The aim of the present study is to report a complete overview regarding medical and surgical management of diabetic foot osteomyelitis (DFO) in combination or alone.

MATERIALS AND METHODS

We performed a search in PubMed and Scopus electronic databases (up to January 2019) of articles assessing the epidemiology, diagnostic strategy and pharmacological treatment of diabetic foot infection. In the search strategy, we used various combinations of the following key terms: infection, orthopaedic, diabetic foot, management, DFO.

RESULTS

This article discusses the definition, epidemiology, microbiological assessment, clinical evaluation, pharmacological and surgical management and a comparison between them, of DFO. After the initial literature search and removal of duplicate records, a total of 756 potentially relevant citations were identified. After a further screening and according to the inclusion criteria, a total of 65 articles were included in the present review.

CONCLUSION

The association of antibiotic and surgical therapy seems to be more effective compared to each one alone. The lack of comparison studies and randomized controlled trials makes it difficult to give information about the efficacy of the different management therapies.

Acute wound infections management: the 'Don'ts' from a multidisciplinary expert panel

Introduction: The management of acute wounds may be affected by malpractices leading to poor outcome, prolonged hospital stay and inappropriate use of antibiotic therapy.Areas covered: Acute wound infections are represented by surgical site and post-traumatic infections. The aim of this expert opinion is to identify a list of inadvisable actions and to provide a guide for an optimal management of acute wound infections. A literature search using Pubmed/MEDLINE database was performed. Articles pertaining to areas covered published until December 2019 were selected. We identified the most common malpractices in this setting and, using the Choosing Wisely methodology, we proposed a list of "Don'ts" for an easy use in clinical practice.Expert opinion: Malpractices may occur from the surgical prophylaxis to the discharge of patient. A prolonged surgical prophylaxis, the underestimation of signs and symptoms, the omission of source control, the inappropriate collection of wound swab, the improper use of clinical microbiology and pharmacology, the lack of hygiene measures and the delay of discharge are all factors that may lead to unfavorable outcome. A multidisciplinary approach is needed to optimally manage these patients. The "Don'ts" refer to all professional figures involved in the management of patients with acute wound infections.

Prospective evaluation of the influence of sampling method on bacterial culture results and antimicrobial selection in 52 dogs with infected wounds

OBJECTIVE

To determine the influence of sampling methods on culture results and selection of antimicrobials for treating infected wounds in dogs.

DESIGN

Prospective study from January to July 2016.

SETTING

Three private multispecialty referral centers.

ANIMALS

Fifty-two client-owned dogs with infected wounds.

INTERVENTIONS

Each wound was sampled for culture by 3 methods: swabbing prior to preparation (dirty swabs), swabbing after debridement and sterile lavage (clean swabs), and biopsy. Bacterial species and phenotypes were compared. Three clinicians unaware of patient, wound, and sampling information selected antimicrobial drugs based on culture and sensitivity reports. Antimicrobials were divided into class I, II, or III based on established guidelines. The number, highest class of antimicrobial chosen, and inter-investigator agreement were examined.

MEASUREMENTS AND MAIN RESULTS

Identical populations of bacteria were isolated for all 3 sampling techniques in only 31% of wounds. Significantly fewer bacterial species were isolated from biopsy samples (1.87 bacterial species per wound ± 1.14) than from clean swab samples (2.29 ± 1.18; P = 0.009) but not dirty swab samples (2.29 ± 1.29; P = 0.06). The recovery frequency for gram-positive bacteria was lower for biopsy compared to either swabbing technique (P = 0.001 for both comparisons). No difference was observed between clean and dirty swabbing techniques for any parameter examined. Sampling technique did not affect the proportion of wounds with anaerobic, gram-negative, or multi-drug resistant bacteria. The number (P = 0.28) and highest class of antimicrobial (P = 0.9) selected per wound did not differ between the 3 sampling techniques (P = 0.28). Clinician agreement was 83-90% depending on sampling technique.

CONCLUSION

Although there were some differences in bacteria isolated from biopsy samples compared to swab samples from infected wounds, technique did not influence the number and highest class of antimicrobial selected by clinicians. Wound debridement prior to sampling by swabbing did not alter the number or type of bacteria isolated, nor the number or the highest class of antimicrobial selected by clinicians.

Microbiology of acute bacterial skin and skin-structure infections in Greece: A proposed clinical prediction score for the causative pathogen

Although clinical definitions of acute bacterial skin and skin-structure infection (ABSSSI) are now well established, guidance of the prediction of likely pathogens based on evidence is missing. This was a large survey of the microbiology of ABSSSIs in Greece. During the period November 2014 to December 2016, all admissions for ABSSSI in 16 departments of internal medicine or surgery in Greece were screened to determine the likely bacterial aetiology. Samples were cultured on conventional media. Expression of the SA442, mecA/mecC and SCCmec-orfX junction genes was assessed. Following univariate and forward logistic regression analysis, clinical characteristics were used to develop scores to predict the likely pathogen with a target of 90% specificity. In total, 1027 patients were screened and 633 had positive microbiology. Monomicrobial infection by Gram-positive cocci occurred in 52.1% and by Gram-negative bacteria in 20.5%, and mixed infection by Gram-positive cocci and Gram-negative bacteria in 27.3%. The most common isolated pathogens were Staphylococcus aureus and coagulase-negative staphylococci. Resistance to methicillin was 57.3% (53.5-61.1%). Three predictive scores were developed: one for infection by methicillin-resistant S. aureus, incorporating recent hospitalisation, atrial fibrillation, residency in long-term care facility (LTCF) and stroke; one for mixed Gram-positive and Gram-negative infections, incorporating localisation of ABSSSI in lumbar area, fluoroquinolone intake in last 6 days, residency in LTCF and stroke; and another for Gram-negative infection, incorporating skin ulcer presentation, peptic ulcer and solid tumour malignancy. In conclusion, methicillin-resistant staphylococci are the main pathogens of ABSSSIs. The scores developed may help to predict the likely pathogen.

Prevalence and Genetic Relatedness of Extended Spectrum-β-Lactamase-Producing Escherichia coli Among Humans, Cattle, and Poultry in Pakistan

Objective: To determine the prevalence and genetic relatedness of bla_CTX-M-type extended spectrum-β-lactamase (ESBL)-producing Escherichia coli at the human-animal interface in Pakistan. Materials and Methods: A total of 150 human, cattle, and poultry fecal samples (50 each) were screened for ESBL-producing E. coli using ESBL CHROMagar^®. Bacterial species confirmation as well as determination of minimum inhibitory concentrations (μg/mL) to different antibiotics was performed using the automated VITEK^®-2 compact system. Phenotypic confirmation of ESBL production was performed according to the Clinical Laboratory Standards Institute (CLSI) guidelines. Genetic analysis of bla_CTX-M was carried out by PCR and DNA sequencing. Plasmids and clonal similarity of the E. coli strains were determined by PCR-based replicon typing and pulsed-field gel electrophoresis (PFGE), respectively. Results: Of 150 samples, 29 (19.3%) ESBL-producing E. coli were recovered, and majority of them originated from human (n = 16; 55%), followed by cattle (n = 9; 31%) and poultry (n = 4; 13.7%). bla_CTX-M-15 was predominant ESBL genotype (n = 25; 86.2%), mainly identified from human (n = 15) and cattle (n = 9). This is also the first report of the occurrence of CTX-M-15 and CTX-M-55 in cattle and poultry E. coli isolates of Pakistan, respectively. The majority of the ESBL-producing E. coli (96.5%) showed a multidrug resistance phenotype. All isolates carried IncFII or IncFIA plasmids, and the phylogroup B1 was dominant (44.8%) followed by phylogroups A (31%), D (17.2%), and B2 (6.8%). PFGE revealed that isolates from different hosts were genetically unrelated. Conclusion: Presence of CTX-M-15-type ESBL-producing E. coli in different reservoirs is alarming and has the potential to impact both veterinary and human therapeutic treatment options.

Diabetic Foot Infections: Update on Management

PURPOSE OF REVIEW

Diabetic foot infections (DFIs) are common in patients with diabetes mellitus complicated by foot ulcers and can be classified in different categories based on their severity. In this report, we present the diagnosis and management of DFIs according to their classification.

RECENT FINDINGS

While appropriate antibiotic regiments and surgical techniques for the treatment of DFIs are well established, new technologies and techniques for example in medical imaging, wound care modalities, and supplementary therapy approaches show potentially promising results in preventing DFIs. As with every complex disease, fine tuning DFI management can be challenging as it requires careful evaluation of different parameters. It demands timely action, close collaboration of different specialties, and patient cooperation.

When and How to Perform Cultures on Chronic Wounds?

PURPOSE

The purpose of this Evidence-Based Report Card was to examine current best evidence related to when and how to perform cultures on chronic wounds to guide clinicians in determining the appropriate treatment.

QUESTION

(1) When should cultures be performed on chronic wounds? and (2) What is the best method or technique to perform a culture on a chronic wound?

SEARCH STRATEGY

A search of the literature was performed, resulting in 45 publications relevant to the topic. Following a review of titles and abstracts, 7 studies were identified that met inclusion criteria. Key search terms used were "chronic wound," "chronic infected wound," "wound culture," "specimen collection," and "wound swab." Strength of the evidence was rated based on the methodology from Essential Evidence Plus: Levels of Evidence and Oxford Center for Evidence-Based Medicine, adapted by Gray and colleagues.

FINDINGS

Seven studies were identified as pertinent to the topic on wound culture and meeting inclusion criteria. The study designs included 1 randomized controlled trial, 1 quasi-experimental comparative study, 1 systematic review, 1 scoping literature review, 1 integrative literature review, and 2 professional organization expert panel reviews (consensus statement and position statement). Of the 7 studies, 3 studies suggest that classic signs of infection may not always be present but culturing may be indicated when additional signs such as pain, necrotic tissue, prolonged or delayed healing, and wound bed deterioration occur. Four studies report that a quantitative culture of wound tissue is the gold standard to obtain a wound culture, but the swab method is an acceptable alternative option. Two articles demonstrate the Levine technique is more reliable than the Z-technique to determine microbial load in the wound bed. The strength of the evidence was identified as 2 level A studies, 1 level B study, and 4 level C studies. Using Johns Hopkins methodology, the quality of the studies was deemed either high quality or good quality.

CONCLUSION/RECOMMENDATION

Evidence indicates that identification of potential chronic wound infection should be considered early using clinical signs such as pain, necrotic tissue, delayed healing, and wound deterioration (in addition to classic signs of infection) to determine the need for collecting a culture (Strength of Recommendation Taxonomy [SORT] level 2); and when a culture is deemed necessary, swab culture using the Levine method is a clinically practical alternative if performed correctly (SORT level 1).

Early wound infection identification using the WIRE tool in community health care settings: An audit report

Wound infection is proving to be a challenge for health care professionals. The associated complications and cost of wound infection is immense and can lead to death in extreme cases. Current management of wound infection is largely subjective and relies on the knowledge of the health care professional to identify and initiate treatment. In response, we have developed an infection prediction and assessment tool. The Wound Infection Risk-Assessment and Evaluation tool (WIRE) and its management strategy is a tool with the aim to bring objectivity to infection prediction, assessment and management. A local audit carried out indicated a high infection prediction rate. More work is being done to improve its effectiveness.

Application of Hyperosmotic Nanoemulsions in Wound Healing: Partial Thickness Injury Model in Swine

Objective: In this work, we introduce a novel hyperosmotic nanoemulsion (HNE) topical agent for use in wound healing. These topical emulsion complexes combine a lipophilic thymol nanoemulsion with a hyperosmotic saccharide matrix. This combination has been previously shown to possess synergistic antimicrobial activity against a host of common and drug-resistant pathogens in vitro. Approach: In this study, we present additional data to assess the safety and efficacy of these emulsions in a partial thickness injury model in swine. Ten wounds sized 2 × 3.5 cm were created in 18 pigs using an electrodermatome set at a depth of 0.76 mm. The wounds were subsequently contaminated with a cocktail of Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, and Candida albicans at 5 × 10⁷ total colony forming unit per wound. Treatments were subdivided in the control group and emulsion concentrations at 0.0%, 0.01%, 0.03%, and 0.063% thymol content. Longitudinal metrics for wound healing included rate of reepithelialization, wound bed color measurements, amount of wound exudate, wound swab culture data, and histological examination at 4, 7, and 14 days. The cosmetics of the healed wound were obtained at day 14 with three-dimensional photogrammetry. Results: Experimental results showed that HNE reduced the wound level bacteria count by ∼0.5-1 log versus controls after 24 h. The amount of pathogen reduction was weakly correlated to the concentration of the emulsion. In addition, all HNE groups maintained a moist wound environment and showed increased fibrin formation and improved hemostatic response. Innovation: No significant difference in the rate of reepithelialization or wound closure was found between treatment concentrations and control groups. HNE treatment did not demonstrate any adverse host tissue response. Conclusion: These results suggest HNE may be a candidate for reducing wound bacterial counts without compromising reepithelialization.

Diabetic Foot Infections: an Update in Diagnosis and Management

Foot infections are a common problem in patients with diabetes and a risk factor for limb amputation. They occur as a result of skin ulceration, which facilitates penetration of pathogens to deeper tissues. The diagnosis of infection is clinical. Aerobic gram-positive cocci are the most common pathogens. Ulcers which are chronic, preceded by administration of antibiotics and hospitalization or complicated by severe infection are polymicrobial. Antibiotic therapy is initially empiric based on the severity of the infection. Definitive therapy is modified according to the results of the microbiological culture and the response to empiric treatment. The optimal duration of antibiotic therapy ranges from 1-2 weeks for mild infections to 2-4 weeks and even longer for severe infections and osteomyelitis. Surgical consultation should be sought for infections complicated with abscesses, necrotizing fasciitis or osteomyelitis. With appropriate care, infection resolves in about 80-90% of non-limb threatening and in about 60% of severe infections.

Wound Infections in Critical Care

Patients admitted to critical care units are at high risk for increased morbidity and mortality from skin and deep wound infections. Despite considerable progress, wound healing remains a challenge to many clinicians. Nurses working in critical care environments need to understand the anatomic and physiologic basis for wound healing, distinguish wound inflammation from wound infection, recognize the presence of biofilms, and implement evidence-based wound care in order to promote successful outcomes in this patient population.

Is a wound swab for microbiological analysis supportive in the clinical assessment of infection of a chronic wound?

AIM

To determine whether bacteriological analysis of a wound swab is supportive in the clinical assessment of infection of a chronic wound.

METHODS

Patients attending an outpatient wound clinic who had endured a chronic wound for more than 3 weeks were clinically assessed for infection. In addition, standardized wound swabs were taken according to the Levine technique and the microbiological findings of the swabs compared with the clinical assessment of the wounds.

RESULTS

There was no significant relationship between the clinical assessments of the chronic wounds and the qualitative or quantitative bacteriological results of the swabs.

CONCLUSION

Microbiological analysis of wound swabs taken from chronic wounds to support clinical assessment of the wounds is waste of time and money. It may be preferable to assess chronic wounds clinically, however, validation studies of these signs and symptoms are needed.

Sample procurement for cultures of infected wounds: a systematic review

OBJECTIVE

Identifying the responsible pathogen is required in order to select optimum antimicrobial therapy for infected wounds, but the best techniques to use remain the subject of debate. Our aim was to assess the evidence on the value of wound swabs compared with biopsies.

METHOD

We conducted a systematic literature review with the terms 'wound infection', 'wound swab', 'wound swab technique', 'wound biopsy', 'wound culture', 'wound swab comparison', 'Levine swab technique', 'microbiological technique', 'specimen handling', 'bacterial load', 'perioperative care', 'swab', and 'culture'. We examined yields in identifying relevant pathogens, summarised salient features of qualifying studies, and defined knowledge gaps and endpoints that future studies should address.

RESULTS

Studies have been inconsistent, lacking specificity regarding wound types, clinical features, and sampling methods. We found moderate quality evidence that punch biopsies provide qualitative and quantitative information about the bacterial load and tissue reaction with nearly 100% sensitivity, 90% specificity and 95% accuracy for predicting wound closure. Biopsies are relatively invasive, costly, require skilled operators, and potentially exacerbate infection. Needle aspiration samples a limited portion and may enter uninfected tissue and extend infection. Wound swabs are minimally invasive, easier to perform and widely employed in clinical practice, but techniques vary. In comparative studies, the Levine technique was superior to the Z-swab techniques, and biopsies were more sensitive for antibiotic-resistant wounds than Levine or Levine-like swabs, suggesting that swabs may be useful for initial wound monitoring, but biopsies are preferred when antibiotic resistance is suspected.

CONCLUSION

The Levine swab is superior to the Z-swab technique and may be useful for initial wound monitoring, but quantitative biopsies are preferred for evaluation of antibiotic-resistant wounds and to monitor the response to treatment. There is limited evidence on the role of wound swabs for detecting wound colonisation versus infection and the impact of culture-guided therapy on such clinical outcomes as eradication of infection and accelerated healing. Future studies should specify patient populations, wound types, sampling protocols, and outcomes based on culture yield and treatment results, using rigorous statistical methodology.

Bacteriology of pressure ulcers in individuals with spinal cord injury: What we know and what we should know

Individuals with spinal cord injury (SCI) are at increased risk for the development of pressure ulcers. These chronic wounds are debilitating and contribute to prolonged hospitalization and worse medical outcome. However, the species of bacteria and the role that specific species may play in delaying the healing of chronic pressure ulcers in the SCI population has not been well characterized. This study will review the literature regarding what is known currently about the bacteriology of pressure ulcers in individuals with SCI. An electronic literature search of MEDLINE (1966 to February 2014) was performed. Eleven studies detailing bacterial cultures of pressure ulcers in the SCI population met inclusion criteria and were selected for review. Among these studies, bacterial cultures were often polymicrobial with both aerobic and anaerobic bacteria identified with culture techniques that varied significantly. The most common organisms identified in pressure ulcers were Staphylococcus aureus, Proteus mirabilis, Pseudomonas aeruginosa, and Enterococcus faecalis. In general, wounds were poorly characterized with minimal to no physical description and/or location provided. Our present understanding of factors that may alter the microbiome of pressure ulcers in individuals with SCI is quite rudimentary, at best. Well-designed studies are needed to assess appropriate wound culture technique, the impact of bacterial composition on wound healing, development of infection, and the optimum medical and surgical approaches to wound care.

Wound samples: moving towards a standardised method of collection and analysis

Chronic wounds, including diabetic foot ulcers, pressure ulcers and venous leg ulcers, impact the lives of millions of people worldwide. These types of wounds represent a significant physical, social and financial burden to both patients and health care systems. Wound care has made great progress in recent years as a result of the critical research performed in academic, clinical and industrial settings. However, there has been relatively little translation of basic research discoveries into novel and effective treatments. One underlying reason for this paucity may be inconsistency in the methods of wound analysis and sample collection, resulting in the inability of researchers to accurately characterise the healing process and compare results from different studies. This review examines the various types of analytical methods being used in wound research today with emphasis on sampling techniques, processing and storage, and the findings call forth the wound care research community to standardise its approach to wound analysis in order to yield more robust and comparable data sets.

Aqueous oxygen peroxide treatment of VLUs in a primary care-based randomised, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate a novel aqueous oxygen peroxide (AOP) wound therapy (BioxyQuell) in a multi-centre, primary care-based, randomised, double-blind, placebo-controlled, parallel-group trial, monitoring long-term healing outcomes over 12 months.

METHOD

Sixty-one patients with chronic, stable venous leg ulceration were treated with either AOP solution or sterile water placebo applied as a lavage over 2 weeks. The patients' wounds were dressed weekly and assessed fortnightly over the following 6 weeks. Patients who completed the initial 8-week trial were invited into a 10-month follow-up trial. The primary endpoints of the study were wound healing at 8 weeks, 12 weeks, 6 months and 12 months, and wound size reduction during the treatment phase. Secondary endpoints were reductions in wound bioburden and pain.

RESULTS

Patients treated with AOP were more likely to heal at 6 months (p=0.014) and 12 months (p=0.006), but not at 8 weeks (p=0.979) or 12 weeks (p=0.263). Patients treated with AOP had greater wound area reduction (p=0.015), reductions in pain measured on a 100-point scale (p=0.001) and wound bioburden reduction (p=0.005) during the treatment phase.

CONCLUSION

The addition of AOP treatment provides substantial benefits to patients with chronic venous leg ulceration compared with current best practice.

Advances and challenges in biosensor-based diagnosis of infectious diseases

Rapid diagnosis of infectious diseases and timely initiation of appropriate treatment are critical determinants that promote optimal clinical outcomes and general public health. Conventional in vitro diagnostics for infectious diseases are time-consuming and require centralized laboratories, experienced personnel and bulky equipment. Recent advances in biosensor technologies have potential to deliver point-of-care diagnostics that match or surpass conventional standards in regards to time, accuracy and cost. Broadly classified as either label-free or labeled, modern biosensors exploit micro- and nanofabrication technologies and diverse sensing strategies including optical, electrical and mechanical transducers. Despite clinical need, translation of biosensors from research laboratories to clinical applications has remained limited to a few notable examples, such as the glucose sensor. Challenges to be overcome include sample preparation, matrix effects and system integration. We review the advances of biosensors for infectious disease diagnostics and discuss the critical challenges that need to be overcome in order to implement integrated diagnostic biosensors in real world settings.

Swab versus biopsy for the diagnosis of chronic infected wounds

OBJECTIVE

The goal of this review was to investigate the usefulness of a wound swab (using the Levine or Z technique) in comparison with a biopsy as a reliable method for the diagnosis of a chronic wound infection.

METHOD

A literature review using the electronic databases PubMed, CINAHL, and MEDLINE were searched by strategy. A total of 6 articles fulfilled the inclusion criteria.

MAIN RESULTS

The Levine technique detects more organisms in acute wounds, as well as in chronic wounds, than the Z technique. Comparing both with the biopsy as criterion standard, the diagnostic accuracy to diagnose a chronic wound infection by the Levine technique was higher in comparison to the Z technique. At a threshold of 3.7 × 10(4) microorganisms per swab, the Levine technique had a sensitivity of 0.90, a specificity of 57%, and a positive predictive value and negative predictive value of 0.77 and 0.91, respectively. Description of the method of swab taking was diverse and not uniform.

DISCUSSION

Only a few studies in the literature compare wound swabs with biopsies for the diagnosis of chronic infected wounds. Until now, the Levine technique has been considered as the most reliable and valid method, but there is an urgent need for a well-designed study with a sufficient number of patients to optimize the diagnostic accuracy of chronic infected wounds.

CONCLUSION

The best sampling technique for taking a swab has not yet been identified and validated. Until then, the authors recommend the Levine technique.

Culture-independence for surveillance and epidemiology

Culture-independent methods in microbiology (quantitative PCR (qPCR), sequencing, microarrays, direct from sample matrix assisted laser desorption/ionization time of flight mass spectroscopy (MALDI-TOF MS), etc.) are disruptive technology. Rather than providing the same results as culture-based methods more quickly, more cheaply or with improved accuracy, they reveal an unexpected diversity of microbes and illuminate dark corners of undiagnosed disease. At times, they overturn existing definitions of presumably well-understood infections, generating new requirements for clinical diagnosis, surveillance and epidemiology. However, current diagnostic microbiology, infection control and epidemiology rest principally on culture methods elegantly optimized by clinical laboratorians. The clinical significance is interwoven; the new methods are out of context, difficult to interpret and impossible to act upon. Culture-independent diagnostics and surveillance methods will not be deployed unless the reported results can be used to select specific therapeutics or infection control measures. To cut the knots surrounding the adoption of culture-independent methods in medical microbiology, culture-dependent methods should be supported by consistent culture-independent methods providing the microbial context. This will temper existing biases and motivate appropriate scrutiny of the older methods and results.

Skin grafting the contaminated wound bed: reassessing the role of the preoperative swab

OBJECTIVE

To investigate use of the preoperative wound swab to predict graft failure compared with establishing the indication for skin grafting on clinical grounds alone.

METHOD

Patients requiring meshed split-thickness skin grafting were prospectively included; the indication for grafting was established on clinical grounds exclusively. A preoperative swab of the wound bed was taken, but its result was concealed to prevent it influencing clinical decision-making. Negative pressure wound therapy (NPWT) was used for both wound bed preparation and graft fixation.After 2 months, graft area take percentage was measured using digital image processing software and the results validated against the result of the preoperative wound swab.

RESULTS

Eighty-seven wounds were included in the study. Mean graft area take percentage was 88%,with five grafts considered complete failures(< 25% take).A posteriori analysis of the wound cultures showed that 53% had been contaminated on grafting, but these did not fare any worse than near-sterile wounds. Qualitative analysis of cultures showed that wounds containing either Pseudomonas aeruginosa or Staphylococcus aureus did have inferior outcome (mean take percentage 78.9% vs 91.3%; p=0.038).Diabetes was also a deteriorating factor (mean take percentage 83.0% vs 90.7%; p=0.004).

CONCLUSION

Establishing the indication for skin grafting on clinical grounds exclusively does not yield grossly inferior results. In light of recent advances in skin grafting, including use of NPWT as adjuvant therapy, the requirement for routine preoperative wound swabs may be questioned.

Risk factors for surgical site infections in abdominal surgery: a study in Nepal

BACKGROUND

Surgical site infection (SSI) remains a major clinical problem for developing countries in terms of morbidity, mortality, and hospital cost. Little is known about the epidemiology of SSI in Nepal. We conducted a study in Nepal to identify the various pre- and intra-operative risk factors for SSIs that are accessible to interventions.

METHODS

The study was a prospective study done on all eligible patients who underwent abdominal surgery in the surgical wards of Tribhuvan University Teaching Hospital (TUTH) in Kathmandu, Nepal, from January 2011 to June 2011. We evaluated some patient-related as well as intra-operative variables that could be risk factors for SSIs. We assessed the association between these risk factors and SSI with the Fisher exact test and logistic regression analysis.

RESULTS

Of the 230 patients included in the study, 53 were identified as having a SSI, resulting in an overall rate of SSI of 23%. Multivariable analysis identified the following factors as independent risk factors for SSI: (1) Low hemoglobin concentrations (<12 g/dL) (odds ratio [OR] 2.5; 95% confidence interval [CI] 1.1-6.1); (2) overweight (OR 7.6; 95% CI 2.1-27.0); and (3) surgery performed by residents (OR 3.4; 95% CI 1.4-8.3).

CONCLUSIONS

Surgical site infection is common among patients undergoing abdominal surgery at TUTH. This study identified some preventable risk factors associated with SSI at TUTH. Identification of such risk factors is expected to help surgeons improve patient care and decrease mortality and morbidity as well as the hospital-care cost of surgical patients.

Tissue and Swab Culture in Diabetic Foot Infections

We evaluated the diagnostic performance of swabs versus tissue cultures in 28 diabetic patients with neuropathic (group A) and 22 diabetic patients with neuroischemic foot ulcer (group B) and the differences in bacterial isolates between the 2 groups. In group A, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of swab cultures for the diagnosis of infection were 100%, 40%, 88.5%, and 100%, respectively. In group B, the corresponding values were 100%, 22.2%, 65%, and 100%. In group A, sensitivity, specificity, PPV, and NPV of swab cultures for the identification of pathogens were 100%, 14.3%, 53.8%, and 100%, respectively. In group B, the corresponding values were 100%, 18.2%, 55%, and 100%. In each group, Staphylococcus aureus and Pseudomonas aeruginosa were the most common isolates. The number of isolates was significantly higher on swab versus tissue cultures only in group A ( P = .033). No differences were observed between groups in number of isolates and colony forming units. In conclusion, swab cultures are highly sensitive but less specific and have an excellent NPV both in diabetic patients with neuropathic and in those with neuroischemic foot ulcer. There are no differences between the groups in microbial load.