Comparison of microbial findings and resistance to antibiotics between transplant patients, patients on hemodialysis, and other patients with the diabetic foot

Abstract

Infectious complications of the diabetic foot may be influenced by impaired renal function and by immunosuppression therapy. Aims: To assess differences in microbial findings and resistance to antibiotics between transplant recipients, hemodialysis patients, and other patients with the diabetic foot. Methods: 207 patients treated in the foot clinic for diabetic ulcers from 12/1998 to 12/1999 were included into this retrospective study. Patients were divided into three groups (transplant, dialysis, and other patients). Occurrence of individual bacterial species and resistance to antibiotics was compared between study groups. Results: Study groups did not differ significantly in ulcer grades defined by the Wagner classification or in the mean number of pathogens per patient. The prevalence of individual microorganisms did not differ between the study groups. However, the study groups differed significantly in the occurrence of microbial resistance to antibiotics. Transplant patients had more frequently Staphylococcus aureus resistant to oxacillin (P<.01), imipenem (P<.01), co-trimoxazole (P<.01), Enterococcus species resistant to ampicillin (P<.01), piperacillin (P<.01), and dialysis patients had more frequently Pseudomonas species resistant to piperacillin (P<.05) and cefpirom (P<.05) in comparison with the other two groups. Conclusions: Transplant patients had significantly more resistant microorganisms in comparison with dialysis and other patients with the diabetic foot. Empiric antibiotic selection based on general population data should be modified in transplant patients with diabetic foot according to actual susceptibility to antibacterial drugs.

Introduction

Infectious complications of the diabetic foot represent one of the most common reasons for the hospitalization of diabetic patients (Urbancic-Rovan & Gubina, 2000). Infection caused by various bacterial agents impairs vessel blood flow and leads to tissue ischemia through septic thrombotisation or mechanic compression of microcirculation by edema (Jirkovská, 2000). Diabetic ulcerations are infected more frequently by a variety of pathogens than nondiabetic ulcerations Hunt, 1992, Lavery et al., 1995, Wheat et al., 1986. Infection present in the diabetic foot must be treated aggressively and promptly, since it can be limb threatening and in special groups of patients (e.g. transplant and dialysis patients), even life-threatening. Infection is the main cause of amputations in 25–50% of diabetic patients Criado et al., 1992, International Working Group, 1999.

Impaired immune functions, especially polymorphonuclear functions, may increase infection incidence in diabetic patients. Some factors such as inadequate metabolic control, presence of diabetic complications (diabetic nephropathy, especially end-stage renal failure), or immunosuppressive drugs have a negative influence on immune functions Delamaire et al., 1997, Fishman & Rubin, 1998, Johnston, 1997.

Diabetic patients suffering from end-stage renal failure and those treated by transplantation represent groups at particular risk of infection, foot ulcers, and lower extremity amputation (Rith Najarian & Gohdes, 2000). The transplanted (Bartoš, Jirkovská, & Kožnarová, 1997) and dialysis patients are predisposed to foot ulcers due to neuropathy, impaired immune functions, associated coronary artery disease (Manske, Wilson, Wang, & Thomas, 1997), peripheral vascular disease Morrissey et al., 1997, Sung et al., 2000, and risk factors such as advanced age and smoking Kalker et al., 1996, Sung et al., 2000. Kalker et al. (1996) have shown that transplanted diabetic patients were at high risk for foot pathology frequently leading to amputation. Sinacore (1999) have found a longer healing time of diabetic foot ulcers in immunosuppressed/transplanted patients in comparison with nonimmunocompromised patients. Increased incidence of infection is one the main causes of the increased mortality of dialysis patients (Ruiz, Gomez, & Schreiber, 1990).

Patients with end-stage renal failure on hemodialysis and transplant patients are frequently treated for the diabetic foot at our foot clinic. The evaluation of differences in microbial findings and in resistance to antibiotics between these risk groups and other patients with the diabetic foot may be important for the selection of an appropriate antibiotic therapy strategy. The aims of our study were to determine the differences in the occurrence of individual bacterial species in swabs from diabetic foot ulcers and in the resistance to antibiotics between transplant patients, patients on hemodialysis, and other patients with the diabetic foot treated at our foot clinic.