Gunalp Uzun

Hyperbaric oxygen therapy as an anti-infective agent

Hyperbaric oxygen therapy (HBOT) involves inhalation of 100% oxygen at supra-atmospheric ambient pressure. HBOT is used as either a primary or adjunctive treatment in the management of infections such as gas gangrene, necrotizing fasciitis, diabetic foot infections, refractory osteomyelitis, neurosurgical infections and fungal infections. HBOT acts as a bactericidal/bacteriostatic agent against anerobic bacteria by increasing the formation of free oxygen radicals. HBOT restores the bacterial-killing capacity of leukocytes in hypoxic wounds by increasing tissue oxygen tensions. In addition, HBOT acts synergistically with a number of antibiotics. This article reviews the anti-infective effects of HBOT and the use of HBOT in the treatment of certain infectious diseases.

Microparticle enlargement and altered surface proteins after air decompression are associated with inflammatory vascular injuries.

Studies in a murine model have shown that decompression stress triggers a progressive elevation in the number of circulating annexin V-coated microparticles derived from leukocytes, erythrocytes, platelets, and endothelial cells. We noted that some particles appeared to be larger than anticipated, and size continued to increase for ≥24 h postdecompression. These observations led to the hypothesis that inert gas bubbles caused the enlargement and particle size could be reduced by hydrostatic pressure. After demonstrating pressure-induced particle size reduction, we hypothesized that annexin V-positive particle changes associated with decompression contributed to their proinflammatory potential. Intravenous injection of naive mice with particles isolated from decompressed mice, but not control mice, caused intravascular neutrophil activation; perivascular neutrophil sequestration and tissue injuries were documented as elevations of vascular permeability and activated caspase-3. These changes were not observed if mice were injected with particles that had been subjected to hydrostatic recompression or particles that had been emulsified by incubation with polyethylene glycol telomere B surfactant. Hydrostatic pressure and surfactant incubation also altered the pattern of proteins expressed on the surface of particles. We conclude that proinflammatory events and vascular damage are due to enlargement of annexin V-coated particles and/or changes in surface marker protein pattern associated with provocative decompression. Injection of annexin V-coated particles from decompressed mice will recapitulate the pathophysiological vascular changes observed following decompression stress.

The implications of the presence of osteomyelitis on outcomes of infected diabetic foot wounds.

Abstract Aim: To assess the effect of the presence of osteomyelitis in patients with a diabetic foot infection. Methods: We reviewed the records of diabetic patients hospitalized at our medical center for a foot infection over a 2-y period. Using clinical, imaging, and microbiology results, we classified each patient as having diabetic foot osteomyelitis (DFO) or not. We then compared several outcome criteria of interest between the 2 groups. Results: Among 73 eligible patients, 37 were in the DFO group (DFO group), while the other 36 were in the soft tissue infection group (STI group). In comparison to the STI group, the DFO group had a significantly longer length of stay (LOS) in the hospital (42 (28.5–51) days vs 19.5 (13.2–29.5) days, p < 0.001), longer duration of antibiotic therapy (46.6 ± 19.9 days vs 22.0 ± 14.6 days, p < 0.001), longer duration of intravenous antibiotic therapy (32.3 ± 16.3 days vs 13.6 ± 14.3 days, p < 0.001), longer duration of wound before admission (44 (31–64.5) days vs 33 (23–45.5) days, p = 0.034), and longer time to wound healing (239.8 ± 108.2 days vs 183.1 ± 73 days, p = 0.011). There were more surgical procedures in the DFO group than in the STI group (24/37 (64.8%) vs 11/36 (30.5%), p = 0.003), and during hospitalization, 22 patients in the DFO group and 5 patients in STI group underwent minor amputation (59.4% vs 13.8%, p < 0.001). Conclusion: The presence of osteomyelitis negatively affects both the treatment and outcome of diabetic foot infections.

How reliable are cultures of specimens from superficial swabs compared with those of deep tissue in patients with diabetic foot ulcers

PURPOSE To assess the reliability of cultures of superficial swabs (SS) by comparing them with cultures of concomitantly obtained deep tissue (DT) specimens in patients with diabetic foot ulcers. METHODS We reviewed clinical and microbiological data from patients with diabetes who presented during a two-year period to our hyperbaric medicine center with a foot ulcer. We identified patients who had at least one concomitantly collected SS and DT pair of specimens sent for culture. RESULTS A total of 89 culture pairs were available from 54 eligible patients, 33 (61.1%) of whom were hospitalized. Wounds were infected in 47 (87.0%) of the patients and 28 (51.9%) patients had received antibiotic therapy within the previous month. Overall, 65 (73%) of the SS and DT pairs had identical culture results, but in 11 (16.9%) cases the cultures were sterile; thus, only 54 (69.2%) of the 78 culture-positive pairs had identical results. Compared with DT, SS cultures yielded ≥1 extra organism in 10 (11.2%) cases, missed at least one organism in 8 (9.0%), and were completely different in 6 (6.7%). When compared to DT culture results, SS cultures had a positive predictive value of 84.4%, negative predictive value of 44.0%, and overall accuracy of 73.0%. CONCLUSIONS In patients with diabetic foot ulcers, results of specimens for culture taken by SS did not correlate well with those obtained by DT. This suggests that SS specimens may be less reliable for guiding antimicrobial therapy than DT specimens.

Effects of Different Doses of Hyperbaric Oxygen on Cisplatin-Induced Nephrotoxicity

Cisplatin, an effective antineoplastic agent, frequently induces acute renal failure in animals and humans. Hyperbaric oxygen (HBO) has been shown to prevent cisplatin-induced nephrotoxicity in rats. This study investigated the effect of two different HBO regimes on renal functions, oxidative stress, and histopathological changes in rat kidneys after cisplatin treatment. Wistar rats were divided into five groups: control, HBO, cisplatin, cisplatin plus once daily HBO, and cisplatin plus twice daily HBO. Cisplatin was given as a single intraperitoneal dose of 6 mg/kg, and HBO was applied for 60 min at 2.5 atm for six days. HBO alone did not alter any biochemical parameters or histopathological findings compared with the control group. Cisplatin increased serum urea and creatinine levels and caused severe histopathological injury. In addition, cisplatin increased lipid peroxidation and impaired superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in kidney tissue. Once daily HBO after cisplatin treatment slightly reduced serum urea and creatinine levels and attenuated histopathological injury. HBO also reduced lipid peroxidation and increased SOD and GSH-Px activities significantly. Although twice daily HBO was determined to be more effective than once daily HBO on oxidative stress parameters, it increased serum creatinine levels and histopathological injury compared with the cisplatin group. It was concluded that HBO alone does not induce nephrotoxicity and oxidative stress in rat kidneys; once daily HBO may prevent cisplatin-induced nephrotoxicity, an effect that is partially mediated by the modification of oxidant/antioxidant systems in the kidneys; and twice daily HBO potentiates cisplatin nephrotoxicity by a ROS-independent mechanism.

Increasing incidence of Gram-negative organisms in bacterial agents isolated from diabetic foot ulcers

INTRODUCTION In the present study, we sought to identify the bacterial organisms associated with diabetic foot infections (DFIs) and their antibiotic sensitivity profiles. METHODOLOGY We retrospectively reviewed the records of wound cultures collected from diabetic patients with foot infections between May 2005 and July 2010. RESULTS We identified a total of 298 culture specimens (165 [55%] wound swab, 108 [36%] tissue samples, and 25 [9%] bone samples) from 107 patients (74 [69%] males and 33 [31%] females, mean age 62 ± 13 yr) with a DFI. Among all cultures 83.5% (223/267) were monomicrobial and 16.4% (44/267) were polymicrobial. Gram-negative bacterial isolates (n = 191; 61.3%) significantly outnumbered Gram-positive isolates (n = 121; 38.7%). The most frequently isolated bacteria were Pseudomonas species (29.8%), Staphylococcus aureus (16.7%), Enterococcus species (11.5%), Escherichia coli (7.1%), and Enterobacter species (7.1%), respectively. While 13.2% of the Gram-negative isolates were inducible beta-lactamase positive, 44.2% of Staphylococcus aureus isolates were methicillin resistant. CONCLUSIONS Our results support the recent view that Gram-negative organisms, depending on the geographical location, may predominate in DFIs.

Combined hyperbaric oxygen and hypothermia treatment on oxidative stress parameters after spinal cord injury: an experimental study.

BACKGROUND AND AIMS We undertook this study to investigate the possible beneficial effects of combined hypothermia and hyperbaric oxygen (HBO) treatment in comparison with methylprednisolone in experimental spinal cord injury (SCI). METHODS Forty eight male Wistar albino rats (200-250 g) were randomized into six groups; A (normothermic control group; only laminectomy), B (normothermic trauma group; laminectomy + spinal trauma), C (normothermic methylprednisolone group; laminectomy + spinal trauma + methylprednisolone treated), D (hypothermia group; laminectomy + spinal trauma + hypothermia treated); E (HBO group; laminectomy + spinal trauma + HBO therapy), F (hypothermia and HBO group; laminectomy + spinal trauma + hypothermia and HBO treated) each containing eight rats. Neurological assessments were performed 24 h after trauma and spinal cord tissue samples had been harvested for both biochemical and histopathological evaluation. RESULTS After SCI, tissue malondialdehyde (MDA) level of the control group was measured increased, and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) enzyme activities were measured decreased. In group F, it was also shown that MDA level elevation had been prevented, and group F has increased the antioxidant enzyme activities than the other experimental groups C, D, E (p <0.05). CONCLUSIONS We concluded that the use of combined hypothermia and HBO treatment might have potential benefits in spinal cord tissue on secondary damage.

Maggot Debridement Therapy in the Treatment of Chronic Wounds in a Military Hospital Setup in Turkey

Background: The medicinal use of maggots for the biological debridement of chronic wounds is increasing around the world, due to its efficacy, safety and simplicity. Thousands of patients have been treated in private and governmental hospitals during the last 10 years. Objective: To examine the efficacy of maggot debridement therapy (MDT) in the debridement of chronic wounds in a militaryhospital. Methods: MDT was applied for 1–9 days to 7 male and 4 female soldiers or their family members (21–72 years old) with chronic wounds. Results: Complete debridement was achieved in 10 out of 11 patients, while in 1 patient the wound could be cleaned only partially. A remarkable reduction in the odor emanating from the wound and notable granulation were observed in all debrided wounds. Increased pain was observed in 1 patient with a venous stasis ulcer. Conclusion: We believe that MDT is a rapid and effective method for the debridement of chronic wounds in a military environment especially in times of war in developing countries.

Cerebral white-matter lesions in asymptomatic military divers.

INTRODUCTION There is some concern that over a period of years, diving may produce cumulative neurological injury even in divers who have no history of decompression sickness. We evaluated asymptomatic divers and controls for cerebral white-matter lesions using magnetic resonance imaging (MRI). METHODS The study enrolled 113 male military divers (34.4 +/- 5.6 yr) and 65 non-diving men (33.1 +/- 9.0 yr) in good health. Exclusion criteria included any condition that might be expected to produce neurological effects. Patent foramen ovale was not assessed. A questionnaire was used to elicit diving history. A 1.5-T MRI device was used to acquire T1, T2-weighted, and fluid attenuated inversion recovery (FLAIR) images of the brain. A lesion was counted if it appeared hyperintense on both T2-weighted and FLAIR images. RESULTS MRI revealed brain lesions in 26 of 113 divers (23%) and in 7 of 65 (11%) controls, a difference that was statistically significant. There was no significant difference between the groups with respect to blood pressure, smoking history, or alcohol consumption, and no subject reported a history of head trauma or migraine. There was no relationship between MRI findings and age, diving history, or lipid profile in divers. DISCUSSION The higher incidence of lesions in the cerebral white matter of divers confirms the possibility that cumulative, subclinical injury to the neurological system may affect the long-term health of military and recreational divers.

Performance of the probe-to-bone test in a population suspected of having osteomyelitis of the foot in diabetes.

BACKGROUND We investigated the validity of probe-to-bone testing in the diagnosis of osteomyelitis in a selected subgroup of patients clinically suspected of having diabetic foot osteomyelitis. METHODS Between January 1, 2007, and December 31, 2008, inpatients and outpatients with a diabetic foot ulcer were prospectively evaluated, and those having a clinical diagnosis of foot infection and at least one of the osteomyelitis clinical suspicion criteria were consecutively included in this study. RESULTS Sixty-five patients met the inclusion criteria and were prospectively enrolled in the study. Forty-nine patients (75.4%) were hospitalized, and the remaining 16 (24.6%) were followed as outpatients. Osteomyelitis was diagnosed in 39 patients (60.0%). Probe-to-bone test results were positive in 30 patients (46.1%). The positive predictive value for the probe-to-bone test was fairly high (87%), but the negative predictive value was only 62%. The sensitivity and specificity of the test were 66% and 84%, respectively. White blood cell counts and mean C-reactive protein levels did not statistically significantly differ between groups. However, erythrocyte sedimentation rates greater than 70 mm/h reached statistical significance between groups. Wound area and depth were not found to be statistically significantly different between groups. CONCLUSIONS Positive probe-to-bone test results and erythrocyte sedimentation rates greater than 70 mm/h provide some support for the diagnosis of diabetic foot osteomyelitis, but it is not strong; magnetic resonance imaging or bone biopsy will probably be required in cases of doubt.