Superficial swab versus deep-tissue biopsy for the microbiological diagnosis of local infection in advanced-stage pressure ulcers of spinal-cord-injured patients: a prospective study

Reliability of superficial swab culture results compared with deep wound culture results in Fournier's gangrene: A retrospective study

OBJECTIVES

To compare isolates from deep wound and superficial swab cultures to evaluate the detectability of pathogens by each culture in Fournier's gangrene; and evaluate the association between microorganisms isolated from deep wounds and those isolated from blood or urine.

METHODS

Patients with Fournier's gangrene who underwent debridement between October 2006 and January 2023 were retrospectively reviewed. In addition to comparing the isolates from deep wound cultures at initial debridement with those from superficial swab, blood, and urine cultures, the relationship between the traits of the organisms from deep wounds and patient disease severity and prognosis was examined.

RESULTS

Among 25 patients, deep wound and superficial swab cultures were obtained from 25 to 18 patients, respectively. The frequency of anaerobic isolates was significantly lower in the superficial cultures than in the deep wound cultures (31/76 versus 13/56, p = 0.034). Bacteria not isolated from deep wounds were isolated from superficial cultures in 55.6 % of the patients; the concordance rate between deep and superficial cultures was 27.8 % (5/18). The positive rates of blood and urine cultures were 20.8 % and 35.7 %, respectively; all isolates from the urine and blood cultures reflected the results of the deep wound culture. No significant association was observed between the severity or mortality and the type of causative bacteria.

CONCLUSIONS

Superficial swab cultures cannot be substituted for deep wound cultures in Fournier's gangrene. Although the positivity rates for blood and urine cultures were not high, they were helpful in determining antibiotic de-escalation.

Identifying infection in chronic wounds in a community setting: A systematic review of diagnostic test accuracy studies

AIM

To determine the diagnostic accuracy of different methods currently available to identify infection in chronic wounds applicable to adult patients in a community setting.

DESIGN

Systematic review of diagnostic test accuracy studies.

REVIEW METHODS

Two authors independently completed screening, data extraction and quality and bias assessments (QUADAS2). Eligible studies compared a method (index test) for detecting infection (diagnosis of interest) with microscopy and culture of either deep tissue biopsy or wound swab (reference test) in adult patients with wounds of >4 weeks duration (participants). The results were synthesized narratively.

DATA SOURCES

We systematically searched CINAHL, Embase and Medline from 2011 to April 2022.

RESULTS

Four studies were included, all recruiting from secondary care wound clinics. Two studies assessed the diagnostic accuracy of Moleculight i:X, a bacterial fluorescence imaging device against deep tissue biopsy culture. One study assessed the diagnostic accuracy of the elevation of various enzymes detected in wound fluid against wound swab microscopy of culture. One study assessed the diagnostic accuracy of bacterial protease activity against wound swab microscopy and culture. Sensitivities of these methods ranged from 50 to 75% and specificities from 47 to 100%.

CONCLUSION

Only a small number of studies were included in this systematic review due to our strict inclusion criteria. We have not identified any methods for diagnosing infection in chronic wounds with either a sufficient quality of evidence to recommend their use in community settings at present. Further research is needed to develop and evaluate appropriate diagnostics for this purpose.

IMPACT

This study highlights the paucity of research into wound diagnostics in a community setting and should prompt further research in this area. Accurate diagnostic tests have the potential to improve community-based wound care by optimizing antibiotic use and potentially improving healing time.

REPORTING METHOD

PRISMA-DTA checklist.

PATIENT OR PUBLIC CONTRIBUTION

The PPI group for the NIHR Community Healthcare MIC were supportive of this topic of work.

Reconstructive Surgery of Pressure Injuries in Spinal Cord Injury/Disorder Patients: Retrospective Observational Study and Proposal of an Algorithm for the Flap Choice

Pressure injuries (PIs) are a common complication in patients with spinal cord injury/disorder (SCI/D), and deep PIs require surgical treatment consisting of wide debridement and adequate reconstruction. We conducted a retrospective observational study at a tertiary rehabilitation hospital for SCI/D in Italy with the aim of describing the incidence and associated risk factors of postoperative complications in individuals with SCI/D presenting with chronic deep PIs, treated with a specific flap selection algorithm based on the site of the defect, the presence of scars from previous surgeries, and the need to spare reconstructive options for possible future recurrences. Medical records of surgical procedures performed on SCI/D patients with fourth-degree PIs, according to NPUAP classification (National Pressure Ulcer Advisory Panel), between July 2011 and January 2018 were reviewed. A total of 434 surgical procedures for fourth-degree PIs in 375 SCI/D patients were analyzed. After a mean follow-up of 21 months (range 12-36), 59 PIs (13.6%) had minor complications, and 17 (3.9%) had major complications requiring reoperation. The sacral site and muscular and musculocutaneous flaps were significant risk factors for postoperative complications. Six patients (1.4%) had a recurrence. The choice of flap correlates with the outcome of decubitus reconstruction. Therefore, reconstructive planning should be based on established principles.

Targeting the Gut-Eye Axis: An Emerging Strategy to Face Ocular Diseases

The human microbiota refers to a large variety of microorganisms (bacteria, viruses, and fungi) that live in different human body sites, including the gut, oral cavity, skin, and eyes. In particular, the presence of an ocular surface microbiota with a crucial role in maintaining ocular surface homeostasis by preventing colonization from pathogen species has been recently demonstrated. Moreover, recent studies underline a potential association between gut microbiota (GM) and ocular health. In this respect, some evidence supports the existence of a gut-eye axis involved in the pathogenesis of several ocular diseases, including age-related macular degeneration, uveitis, diabetic retinopathy, dry eye, and glaucoma. Therefore, understanding the link between the GM and these ocular disorders might be useful for the development of new therapeutic approaches, such as probiotics, prebiotics, symbiotics, or faecal microbiota transplantation through which the GM could be modulated, thus allowing better management of these diseases.

Multidisciplinary treatment protocol for ischiatic, sacral, trochanteric or other pressure injuries in people with spinal cord injury: a retrospective cohort study

STUDY DESIGN

Retrospective cohort study Objectives: to describe the incidence and the associated risk factors of post-surgical complications and recurrence in individuals with spinal cord injury/disorder (SCI/D) presenting deep pressure injuries (PIs), treated with a specific surgical and rehabilitation treatment protocol.

SETTING

Tertiary Rehabilitation Hospital for SCI/D in Italy.

METHODS

Retrospective analysis of the medical records of adult individuals with SCI/D, who developed a PI after the first discharge from a Spinal Unit, underwent flap surgery for PI between July 2011 and January 2018. The statistical unit of analysis was the surgical intervention. Logistic regression analysis with robust standard errors was performed to assess risk factors of post-surgical complications.

RESULTS

434 surgical intervention records were included, for a total of 378 patients. The treated PIs were ischiatic in 56.2% of the cases, sacral in 32.5%, trochanteric in 15.7%, and 5.8% were in other sites. In 239 cases (55.1%) a histological diagnosis of osteomyelitis was confirmed. Minor complications occurred in 13.6% of interventions, while major complications were 3.9%. Sacral PI (OR = 2.55, 95%CI: 1.50-4.35) and muscular/musculocutaneous flap (OR = 2.12, 95%CI: 1.05-4.28) were significant factors associated with risk of post-surgical complications. After a mean follow-up of 21 months (range 12-36), six people (1.4%) had a recurrence. Patients with a recurrence had at least one comorbidity compared to 57% of people without recurrences (p = 0.036).

CONCLUSION

Our results demonstrate that complication and recurrence rates can be minimized when an established interdisciplinary and rehabilitation protocol is integrated in the clinical management.

Wound swabs versus biopsies to detect methicillin resistant Staphylococcus aureus in experimental equine wounds

OBJECTIVE

To compare: (1) the load and diversity of cultivatable bacterial species isolated from tissue biopsies with cultures from surface swabs, and (2) the ability of each technique to detect methicillin-resistant Staphylococcus aureus (MRSA) in a model of MRSA-infected equine wounds.

STUDY DESIGN

Experimental in vivo study.

ANIMALS

Three light-breed adult horses.

METHODS

Four 2.5 × 2.5 cm full-thickness skin wounds were created on the dorsolateral aspect of each forelimb. Five days later, each wound was inoculated with a pure culture of MRSA (ATCC 43300). One hundred microlitres of 0, 5 × 108 , 5 × 109 or 5 × 1010 colony forming units (CFU)/ml was used to inoculate each wound. Surface swabs (Levine technique) and tissue biopsy samples (3 mm punch biopsy) were obtained at 2, 7, 14, and 21 days after inoculation. Quantitative aerobic culture was performed using routine clinical techniques.

RESULTS

A similar bacterial profile was identified from the culture of each wound-sampling technique and there was moderate correlation (R = 0.49, P < .001) between the bacterial bioburdens. Agreement was fair (κ = 0.31; 95% CI, 0.129-0.505) between the sampling techniques in identification of MRSA. Methicillin-resistant Staphylococcus aureus was isolated more frequently (P = .016) from cultures of tissue biopsies (79%; 76/96) than from surface swabs (62%; 60/96).

CONCLUSION

Bacterial load and diversity did not differ between sampling techniques but MRSA was detected more often from the cultures of tissue biopsies.

CLINICAL SIGNIFICANCE

Tissue biopsy should be preferred to culture swab in wounds where MRSA is suspected.

Positive Bacterial Culture among Suspected Orthopedic Infections in a Tertiary Care Centre: A Descriptive Cross-sectional Study

Introduction

A hospital-based investigation of bacteriological isolates helps to identify common causative bacteria and their antibiotic sensitivity patterns. This helps in formulating presumptive antibiotic therapy and in reducing antibiotic misuse. The aim of this study was to find out the prevalence of positive bacterial culture isolates among suspected orthopaedic infections in a tertiary care centre.

Methods

A descriptive cross-sectional study was conducted from the electronic data record of the Department of Microbiology of a tertiary care centre from 1 January 2017 to 31 December 2021. The study was conducted following ethical approval from the Institutional Review Committee (Reference number: IRC-2021-11-09-1). Culture reports of suspected orthopaedic infections were evaluated, and those with missing data were excluded. A convenience sampling method was used. Point estimate and 95% Confidence Interval were calculated.

Results

Out of 6201 specimens, positive bacterial culture were found in 2957 (47.69%) (46.45-48.93, 95% Confidence Interval). Among them, 1561 (56.01%) were gram-negative organisms and 677 (24.29%) were gram-positive. A total of 2787 (94.25%) were wound/pus swab cultures and 170 (5.74%) were tissue cultures.

Conclusions

The prevalence of positive bacterial culture among suspected orthopaedic infections was lower than in other international studies. Among bacteriological isolates, gram-negative organisms are more than gram-positive organisms.

Keywords

culture techniques; infections; microbial sensitivity tests; prevalence.

Sampling the fish gill microbiome: a comparison of tissue biopsies and swabs

Background

Understanding the influence of methodology on results is an essential consideration in experimental design. In the expanding field of fish microbiology, many best practices and targeted techniques remain to be refined. This study aimed to compare microbial assemblages obtained from Atlantic salmon (Salmo salar) gills by swabbing versus biopsy excision. Results demonstrate the variation introduced by altered sampling strategies and enhance the available knowledge of the fish gill microbiome.

Results

The microbiome was sampled using swabs and biopsies from fish gills, with identical treatment of samples for 16S next generation Illumina sequencing. Results show a clear divergence in microbial communities obtained through the different sampling strategies, with swabbing consistently isolating a more diverse microbial consortia, and suffering less from the technical issue of host DNA contamination associated with biopsy use. Sequencing results from biopsy-derived extractions, however, hint at the potential for more cryptic localisation of some community members.

Conclusions

Overall, results demonstrate a divergence in the obtained microbial community when different sampling methodology is used. Swabbing appears a superior method for sampling the microbiota of mucosal surfaces for broad ecological research in fish, whilst biopsies might be best applied in exploration of communities beyond the reach of swabs, such as sub-surface and intracellular microbes, as well as in pathogen diagnosis. Most studies on the external microbial communities of aquatic organisms utilise swabbing for sample collection, likely due to convenience. Much of the ultrastructure of gill tissue in live fish is, however, potentially inaccessible to swabbing, meaning swabbing might fail to capture the full diversity of gill microbiota. This work therefore also provides valuable insight into partitioning of the gill microbiota, informing varied applications of different sampling methods in experimental design for future research.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02374-0.

Diagnostic Accuracy of Point-of-Care Fluorescence Imaging for the Detection of Bacterial Burden in Wounds: Results from the 350-Patient Fluorescence Imaging Assessment and Guidance Trial

Objective: High bacterial load contributes to chronicity of wounds and is diagnosed based on assessment of clinical signs and symptoms (CSS) of infection, but these characteristics are poor predictors of bacterial burden. Point-of-care fluorescence imaging (FL) MolecuLight i:X can improve identification of wounds with high bacterial burden (>10⁴ colony-forming unit [CFU]/g). FL detects bacteria, whether planktonic or in biofilm, but does not distinguish between the two. In this study, diagnostic accuracy of FL was compared to CSS during routine wound assessment. Postassessment, clinicians were surveyed to assess impact of FL on treatment plan. Approach: A prospective multicenter controlled study was conducted by 20 study clinicians from 14 outpatient advanced wound care centers across the United States. Wounds underwent assessment for CSS followed by FL. Biopsies were collected to confirm total bacterial load. Three hundred fifty patients completed the study (138 diabetic foot ulcers, 106 venous leg ulcers, 60 surgical sites, 22 pressure ulcers, and 24 others). Results: Around 287/350 wounds (82%) had bacterial loads >10⁴ CFU/g, and CSS missed detection of 85% of these wounds. FL significantly increased detection of bacteria (>10⁴ CFU/g) by fourfold, and this was consistent across wound types (p < 0.001). Specificity of CSS+FL remained comparably high to CSS (p = 1.0). FL information modified treatment plans (69% of wounds), influenced wound bed preparation (85%), and improved overall patient care (90%) as reported by study clinicians. Innovation: This novel noncontact, handheld FL device provides immediate, objective information on presence, location, and load of bacteria at point of care. Conclusion: Use of FL facilitates adherence to clinical guidelines recommending prompt detection and removal of bacterial burden to reduce wound infection and facilitate healing.

Ocular Microbiota and Intraocular Inflammation

The term ocular microbiota refers to all types of commensal and pathogenic microorganisms present on or in the eye. The ocular surface is continuously exposed to the environment and harbors various commensals. Commensal microbes have been demonstrated to regulate host metabolism, development of immune system, and host defense against pathogen invasion. An unbalanced microbiota could lead to pathogenic microbial overgrowth and cause local or systemic inflammation. The specific antigens that irritate the deleterious immune responses in various inflammatory eye diseases remain obscure, while recent evidence implies a microbial etiology of these illnesses. The purpose of this review is to provide an overview of the literature on ocular microbiota and the role of commensal microbes in several eye diseases. In addition, this review will also discuss the interaction between microbial pathogens and host factors involved in intraocular inflammation, and evaluate therapeutic potential of targeting ocular microbiota to treat intraocular inflammation.

Sit bath systems: A new source of Legionella infection

Sit Bath Systems (SBSs) are the most common hygiene method for patients who are not self-sufficient. Therefore, the water quality of SBSs in the nosocomial environment plays a fundamental role in controlling infections for both patients and health-care workers. A long-term study on Legionella and Pseudomonas aeruginosa (P. aeruginosa) contamination was performed in SBSs (n = 20) of six Health Care Facilities (HCFs). A total of 254 water samples were analyzed following ISO procedures. The samples were positive for P. aeruginosa (46.85%) and Legionella (53.54%), respectively, both over the directive limits. Legionella isolates were identified as: Legionella pneumophila (L. pneumophila) serogroups 1, 3, and 6 and Legionella non-pneumophila species (L. anisa, L. londiniensis, L. rubrilucens, and L. nagelii). Moreover, the contamination found was studied with respect to median temperature measured (42 °C), from which two groups (A and B) could be distinguished. P. aeruginosa was found in both groups (100% of SBSs), while a higher percentage of Legionella positive samples was found in group A (75% of SBSs), compared to group B (50% of SBSs), showing how Legionella control could be carried out by using temperatures above 42 °C. An analysis of SBS water pipelines, maintenance, and disinfection treatments indicates SBSs as a new source of infection risk for both patients and health-care workers.

Multiple Flaps for Trochanteric Pressure Sore Reconstruction: A Case Series

Trochanteric pressure sores can be quite difficult to treat, especially in cases of large bone involvement requiring a wide debridement. The residual wound is large and deep, and the reconstruction must ensure a complete fill of all dead spaces, then must be covered with adequate tissue to allow for healing, and reduce the risk of recurrence.

We report a case series of spinal cord-injured patients affected by a trochanteric pressure sore. The reconstruction was achieved using a combination of muscle and a cutaneous muscle flap from the thigh. The result was complete healing of the wound with no recurrence at 18 months.

In these cases, muscle or musculocutaneous flaps are the better choices because they permit the use of a good volume of viable tissue. In some cases, the flap can be combined to obtain a better result.

Skin-stretching device promotes the treatment effect of vacuum sealing drainage technique on phases III and IV stress-induced injuries in aged patients with chronic critical illness: A retrospective study of 70 patients

Stress-induced injury is a common complication associated with patients with chronic critical illness (CCI). Skin-stretching device (SSD) and vacuum sealing drainage (VSD) technique are 2 approaches that can facilitate wound healing.In the present study, the effect of the concatenated application of the 2 techniques on the phases III and IV stress-induced injuries in aged patients with CCI was assessed. About 70 patients with CCI with stress-induced injuries were selected from February 2015 to October 2017. The treatment outcomes of the combined method and VSD method were assessed by comparing their clinicopathologic parameters.The results showed that the combined treatment shortened the average healing duration of wounds. Moreover, the total area of pressure sores, incidence of bleeding, bacteria amount, 28-day cure rate, peripheral C-reactive protein (CRP) level, and the hospitalization duration were all significantly improved in patients treated with SSD and VSD. The overall effective rate (97.14%) of patients treated with VSD and SSD was significantly higher than that (77.14%) in patients treated with VSD.The present study showed that the combined application of VSD and SSD improved the treatment outcomes of phases III and IV stress-induced injuries in aged patients with CCI.

Getting it right first time: The importance of a structured tissue sampling protocol for diagnosing fracture-related infections

INTRODUCTION

Fracture-related infection (FRI) is an important complication following surgical fracture management. Key to successful treatment is an accurate diagnosis. To this end, microbiological identification remains the gold standard. Although a structured approach towards sampling specimens for microbiology seems logical, there is no consensus on a culture protocol for FRI. The aim of this study is to evaluate the effect of a structured microbiology sampling protocol for fracture-related infections compared to ad-hoc culture sampling.

METHODS

We conducted a pre-/post-implementation cohort study that compared the effects of implementation of a structured FRI sampling protocol. The protocol included strict criteria for sampling and interpretation of tissue cultures for microbiology. All intraoperative samples from suspected or confirmed FRI were compared for culture results. Adherence to the protocol was described for the post-implementation cohort.

RESULTS

In total 101 patients were included, 49 pre-implementation and 52 post-implementation. From these patients 175 intraoperative culture sets were obtained, 96 and 79 pre- and post-implementation respectively. Cultures from the pre-implementation cohort showed significantly more antibiotic use during culture sampling (P =  0.002). The post-implementation cohort showed a tendency more positive culture sets (69% vs. 63%), with a significant difference in open wounds (86% vs. 67%, P =  0.034). In all post-implementation culture sets causative pathogens were cultured more than once per set, in contrast to pre-implementation. Despite stricter tissue sampling and culture interpretation criteria, the number of polymicrobial infections was similar in both cohorts, approximately 29% of all culture sets and 44% of all positive culture sets. Significantly more polymicrobial cultures were found in early infections in the post-implementation cohort (P =  0.048). This indicates a better yield in the new protocol.

CONCLUSION

A standardised protocol for intraoperative sampling for bacterial identification in FRI is superior than an ad-hoc approach. It has a positive effect on both surgeon and microbiologist by increasing awareness about the problem at hand. This resulted in more microbiologically confirmed infections and more certainty when identifying causative pathogens.

How the Pathologist Can Help the Surgeon Collect Better Specimens for Microbiology Culture

CONTEXT.—

Specimen quality is paramount for microbiology culture in order to ensure the testing is performed appropriately and the results, generated accurately, reflect the patient's clinical situation and guide proper treatment. Several factors play a critical role in guaranteeing the accuracy of the culture results, including adequate specimen collection by the surgeon, proper labeling, and timely transport to the laboratory.

OBJECTIVE.—

To educate pathologists, surgeons, and other medical personnel involved in the collection and processing of surgical specimens submitted for microbiologic culture. To assure the pathogen is correctly identified, proper protocols must be followed. The accurate identification of the infectious microorganisms from surgical specimens is vital for the treating clinician to ensure the correct antimicrobial therapy is administered.

DATA SOURCES.—

An analysis of relevant literature was performed by using PubMed. Articles were selected on the basis of their relevance to the topic as well as their date of publication. Articles published between 2000 and 2018 were deemed sufficient for inclusion, while older references, regardless of relevance, were excluded.

CONCLUSIONS.—

The process of properly obtaining specimens for microbiology culture from the operating room is a complex process that requires collaboration between the collecting surgeon and the pathologist and microbiology laboratory in order to provide the highest quality of results from which important treatment decisions are then implemented. Engaging leadership to develop mutually agreed-upon institutional best practices will help not only to standardize practices but also to improve the quality of microbiology results reported.

A Comparative Study of Bacteriological Culture Results Using Swab and Tissue in Open Fractures: A Pilot Study

Introduction:

The role of perioperative cultures to identify infection in open fractures has been doubtful. The method of sampling for cultures in open fractures includes swab or tissue collection. However, the efficacy of either of these two techniques has not been compared in the setting of an acute open fracture. We conducted a study to compare the bacteriological culture results between the two techniques.

Methodology:

A pilot study was done at our institution, where all type 2, 3A, and 3B open fractures admitted in the emergency and operated for debridement and stabilization were included in the study. Intraoperatively, after debridement of the wound, swab and tissue specimens were collected and sent to the same laboratory. The results of the cultures were then collected for comparison after the necessary incubation period. Follow-up of outpatient records was also done to see its clinical significance.

Results:

A total of 30 samples of swab and tissue cultures collected post-debridement of acute open fractures in the operation theater were studied. Only 13 samples grew an organism either in swab/tissue culture or both. Nine tissue samples and eight swab samples showed growth. In four cases, both swab and tissue showed growth, but the same organism grew in only one instance. The other three cases showing growth in both tissue and swab had different organisms. Statistically, the kappa coefficient was found to be 0.26 and the agreement between swab and tissue culture was found fair. However, the kappa did not account for the species of the organisms. Tissue samples showed more number of specific organism growing in them, compared to swab culture samples.

Conclusion:

The ideal technique of taking samples for culture in acute open fractures is uncertain. Tissue culture may be better in isolating specific organisms in an acute open fracture wound. However, it is uncertain if the same organism may cause infection.