Impact of high prevalence of pseudomonas and polymicrobial gram-negative infections in major sub-/total traumatic amputations on empiric antimicrobial therapy: a retrospective study

Limb salvage in traumatic hemipelvectomy: case series with surgical management and review of the literature

BACKGROUND

Traumatic hemipelvectomies are rare and serious injuries. The surgical management was described in several case studies, with primary amputation often performed to save the patient's life.

METHODS

We report of two survivors with complete traumatic hemipelvectomy resulting in ischemia and paralyzed lower extremity. Due to modern emergency medicine and reconstructive surgery, limb salvage could be attained. Long-term outcome with quality of life was assessed one year after the initial accident.

RESULTS AND CONCLUSIONS

The patients were able to mobilize themselves and live an independent life. The extremities remained without function and sensation. Urinary continence and sexual function were present and the colostomy could be relocated in both patients. Both patients support limb salvage, even having difficulties and follow-up treatments. Concomitant cases are required to consolidate the findings.

LEVEL OF EVIDENCE

IV.

Secondary amputation after lower extremity free-flap reconstruction

BACKGROUND

Microsurgical free-tissue transfer is often the definitive reconstructive option for lower extremity limb salvage. Despite an initial successful free-flap reconstruction, some patients ultimately undergo lower extremity amputation. The indications for secondary amputation include non- or malunion, infection, hardware failure, or chronic pain. This study aimed to identify the etiology and outcome of secondary amputation after lower extremity free-flap reconstruction.

METHODS

A retrospective cohort study was performed including patients who underwent lower extremity free-flap reconstruction from January 2002 to December 2020. Patients who underwent secondary amputation were identified. A survey based on the PROMIS® Pain Interference Scale and activities of daily living (ADLs) was then conducted to assess patient-reported outcomes. Fifteen (52%) patients who underwent amputation responded to the survey, with a median follow-up time of 4.4 years.

RESULTS

Of 410 patients who underwent lower extremity free-flap reconstruction, 40 (9.8%) patients underwent subsequent amputation. Of these, 10 patients had failed free-flap reconstruction and 30 patients had secondary amputation after an initially successful soft tissue coverage. The most common etiology for secondary amputation was infection (68%, n = 27). Eighty percent (n = 12) of survey respondents were able to use a prosthetic limb and ambulate.

CONCLUSIONS

The most common etiology of secondary amputation was infection. Most patients who ultimately underwent amputation were able to ambulate with a prosthetic, but the majority of patients reported chronic pain. This study could be used to guide potential free-flap candidates regarding the risks and outcomes of lower extremity free-flap reconstruction.

Effect of polymicrobial interactions on antimicrobial resistance: an in vitro analysis in human ocular infections

Purpose: Investigate the effect of polymicrobial interactions on antimicrobial resistance (AMR) of ocular pathogens in polymicrobial settings, compared with monomicrobial infections. Methods: Polymicrobial interactions were labeled as antagonistic, synergistic or indifferent based on a reduction, an increase or no change, respectively, in antibiotics' MIC by the Vitek 2 compact system, compared with monomicrobial pathogens. Results: Staphylococcus epidermidis showed antagonistic polymicrobial interactions (22.6%); Pseudomonas aeruginosa showed synergistic interactions (62.5%); multidrug-resistant Acinetobacter baumannii showed increased susceptibility to select antibiotics; Serratia ficaria (inherently colistin resistant) became colistin-susceptible in polymicrobial combinations. Conclusion: Both antagonistic and synergistic interactions exist among human pathogens in polymicrobial settings. Gram-positive pathogens had significantly higher antagonistic polymicrobial interactions (increased MICs: 20.4%) compared with Gram-negative ones (synergistic: 59.4%).

Preventing Pseudomonas aeruginosa Biofilms on Indwelling Catheters by Surface-Bound Enzymes

Implanted medical devices such as central venous catheters are highly susceptible to microbial colonization and biofilm formation and are a major risk factor for nosocomial infections. The opportunistic pathogen Pseudomonas aeruginosa uses exopolysaccharides, such as Psl, for both initial surface attachment and biofilm formation. We have previously shown that chemically immobilizing the Psl-specific glycoside hydrolase, PslG_h, to a material surface can inhibit P. aeruginosa biofilm formation. Herein, we show that PslG_h can be uniformly immobilized on the lumen surface of medical-grade, commercial polyethylene, polyurethane, and polydimethylsiloxane (silicone) catheter tubing. We confirmed that the surface-bound PslG_h was uniformly distributed along the catheter length and remained active even after storage for 30 days at 4 °C. P. aeruginosa colonization and biofilm formation under dynamic flow culture conditions in vitro showed a 3-log reduction in the number of bacteria during the first 11 days, and a 2-log reduction by day 14 for PslG_h-modified PE-100 catheters, compared to untreated catheter controls. In an in vivo rat infection model, PslG_h-modified PE-100 catheters showed a ∼1.5-log reduction in the colonization of the clinical P. aeruginosa ATCC 27853 strain after 24 h. These results demonstrate the robust ability of surface-bound glycoside hydrolase enzymes to inhibit biofilm formation and their potential to reduce rates of device-associated infections.

Value of PCR in sonication fluid for the diagnosis of orthopedic hardware-associated infections: Has the molecular era arrived?

INTRODUCTION

Bone healing disturbance following fracture fixation represents a continuing challenge. We evaluated a novel fully automated polymerase chain reaction (PCR) assay using sonication fluid from retrieved orthopedic hardware to diagnose infection.

PATIENTS AND METHODS

In this prospective diagnostic cohort study, explanted orthopedic hardware materials from consecutive patients were investigated by sonication and the resulting sonication fluid was analyzed by culture (standard procedure) and multiplex PCR (investigational procedure). Hardware-associated infection was defined as visible purulence, presence of a sinus tract, implant on view, inflammation in peri-implant tissue or positive culture. McNemar's chi-squared test was used to compare the performance of diagnostic tests. For the clinical performance all pathogens were considered, whereas for analytical performance only microorganisms were considered for which primers are included in the PCR assay.

RESULTS

Among 51 patients, hardware-associated infection was diagnosed in 38 cases (75%) and non-infectious causes in 13 patients (25%). The sensitivity for diagnosing infection was 66% for peri-implant tissue culture, 84% for sonication fluid culture, 71% (clinical performance) and 77% (analytical performance) for sonication fluid PCR, the specificity of all tests was >90%. The analytical sensitivity of PCR was higher for gram-negative bacilli (100%), coagulase-negative staphylococci (89%) and Staphylococcus aureus (75%) than for Cutibacterium (formerly Propionibacterium) acnes (57%), enterococci (50%) and Candida spp. (25%).

CONCLUSION

The performance of sonication fluid PCR for diagnosis of orthopedic hardware-associated infection was comparable to culture tests. The additional advantage of PCR was short processing time (<5 h) and fully automated procedure. With further improvement of the performance, PCR has the potential to complement conventional cultures.

[Infected osteosynthesis]

BACKGROUND

Infections after osteosynthesis are a feared complication of the surgical treatment of fractures and should be dealt with by a multidisciplinary team. In addition to the surgeon, also included in this multidisciplinary team are a specialist for infectious diseases, a microbiologist, a radiologist and often a plastic surgeon. This review article describes the current knowledge on the pathogenesis, diagnostics, classification and treatment. The aim is to demonstrate some basic rules in the treatment of infections associated with implants and to show potential therpeutic approaches.

MATERIAL AND METHODS

The principles of diagnostics and combined surgical and antibiotic treatment are presented based on the current specialist literature.

RESULTS

With the help of a team approach the goals of treatment of an infected osteosynthesis, i.e. fracture healing, return to function and eradication of infection can be achieved. While the osteosynthesis material can usually be retained in acute infections, it is better to remove the infected hardware in chronic infections as eradication of the mature biofilm is no longer possible.

DISCUSSION

With adequate local wound débridement, the use of local and systemic antibiotics, as indicated by the specialist for infectious diseases and appropriate soft tissue coverage and wound closure, acute as well as chronic infections can be successfully treated. Nowadays, the surgeon has many different options for the management of bone defects. Depending on the anatomical location and the size of the defect a variety of techniques ranging from acute shortening to the Masquelet technique up to the Ilizarov distraction technique are available. These techniques should be combined with local bactericidal treatment.

Effectiveness of a Short-Term Treatment of Oxygen-Ozone Therapy into Healing in a Posttraumatic Wound

Introduction. A number of studies suggest that oxygen-ozone therapy may have a role in the treatment of chronic, nonhealing, or ischemic wounds for its disinfectant and antibacterial properties. Nonhealing wounds are a significant cause of morbidity. Here we present a case of subcutaneous oxygen-ozone therapy used to treat a nonhealing postoperative wound in a young man during a period of 5 weeks. Case Presentation. A 46-year-old man had a motorcycle accident and underwent amputation of the right tibia and fibula. At the discharge he came to our attention to start rehabilitation treatment. At that time the wound was ulcerated but it was afebrile with no signs of inflammation and negativity to blood tests. At 2 months from the trauma despite appropriate treatment and dressing, the wound was slowly improving and the patient complained of pain. For this reason in addition to standard dressing he underwent oxygen-ozone therapy. After 5 weeks of treatment the wound had healed. Conclusion. In patients with nonhealing wounds, oxygen-ozone therapy could be helpful in speeding the healing and reducing the pain thanks to its disinfectant property and by the increase of endogenous oxygen free radicals' scavenging properties. Compared to standard dressing and other treatments reported in the literature it showed a shorter time of action.

The incidence and microbiological profile of surgical site infections following internal fixation of closed and open fractures

Objective

To evaluate the incidence and microbiological profile of surgical site infections (SSIs) associated with internal fixation of fractures and to compare differences in the SSIs observed among patients with closed and open fractures.

Methods

Retrospective study. Analyzed data included information from all patients who underwent surgery for fixation of closed or open fractures from January 2005 to December 2012 and remained outpatients for at least one year following surgery. Incidence of surgical site infection (SSI) was compared between patients with closed and open infection, as well as polymicrobial infection and infection related to Gram-negative bacilli (GNB). Cumulative antibiograms were performed to describe microbiological profiles.

Results

Overall incidence of SSI was 6%. This incidence was significantly higher among patients with open fractures (14.7%) than among patients with closed fractures (4.2%). The proportions of patients with polymicrobial infections and infections due to GNB were also significantly higher among patients with open fractures. Staphylococcus aureus and coagulase-negative Staphylococcus (CoNS) species were the primary infectious agents isolated from both groups. The overall incidence of MRSA (methicillin-resistant S. aureus) was 72%. A. baumannii was the predominant GNB isolate recovered from patients with open fractures and P. aeruginosa was the most frequent isolate recovered from patients with closed fractures, both exhibited low rates of susceptibility to carbapenems.

Conclusions

Incidence of SSIs related to the internal fixation of fractures was significantly higher among patients with open fractures, indicating that an open fracture can be a risk factor for infection. Among the bacterial isolates, S. aureus (with a high prevalence of MRSA) and CoNS species were most prevalent. A. baumannii and P. aeruginosa isolates underscored the low rate of susceptibility to carbapenems that was observed in the present study.

Vancomycin-Resistant Pseudomonas Aeroginosa in the Cases of Trauma

Background:

One of the main problems in the treatment of cases of P. aeruginosa especially in the orthopedic infections is the occurrence of high antibiotic resistance. The present study was carried out in order to investigate the prevalence of vancomycin-resistant P. aeruginosa in the cases of trauma in Iran.

Methods:

Two hundred and fifty swab samples were collected from the site of trauma from the patients who referred to the orthopedic wards of the Iranian health centers. Samples were cultured immediately and those that were P. aeruginosa-positive were analyzed by the disk diffusion method.

Results:

Of 250 swab samples collected, 43 were positive for P. aeruginosa (17.2%). The results of the culture technique were also confirmed by the PCR reaction. Of 43 P. aeruginosa isolates, 32 strains (74.41%) were resistant to vancomycin. Total prevalence of bacteria in Tehran and Mashhad hospitals were 18.46% and 15.83%, respectively. Statistically significant difference was seen for the prevalence of vancomycin-resistant P. aeruginosa between the samples collected from Tehran and Mashhad (P =0.027). More than 55 years old and less than 10 years old patients had the highest prevalence of P. aeruginosa. P. aeruginosa strains of male and more than 55 years old patients harbored the highest levels of resistance against vancomycin.

Conclusions:

It is logical to primary identification of type of bacteria causing infection in the site of trauma and then using from the disk diffusion method to choose the best antimicrobial agent. Highest levels of health care should be performed for the patients less than 10 years and more than 55 years old patients.