Background: Myeloperoxidase (MPO), an iron-containing protein, is found in the azurophilic granules of neutrophils (PMNs), and catalyzes the conversion of hydrogen peroxide and chloride ions (Cl) into hypochlorous acid, which plays an important role in oxygen-dependent bacterial killing. The enzyme was first isolated in 1941, and deficiency of MPO was first described in 1954. Fewer than 5% of patients with MPO deficiency contract severe infections, which are usually fungal infections in diabetes mellitus (DM) patients. Besides the disorder in antifungal activity, diminished rate of bacterial (S. aureus) killing, and carcinogenesis, it seems that MPO deficiency is also related to atherosclerosis, degenerative neurologic diseases, as well as other disorders. In this study, we compared the levels of the MPO enzyme in the peripheral neutrophils of infected and non-infected DM patients at Imam Khomeini Hospital during 2005-2006. We compared these two groups the prevalence of MPO deficiency in each group, in order to then determine any correlations this may have with infection.

Methods: In this case-control study, 50 patients were in the infected group (case group) and 50 were in the control group. Patients were chosen using simple sampling methods. Data was gathered from blood samples, using a qualitative test to determine MPO deficiency (Kaplow stain), laboratory results (BUN, Cr, PMN, HbA1c), interviews and completion of a questionnaires, as well as hospital records. Data were analyzed with SPSS software using T test and chi-square test, with a confidence index of 0.05.

Results: In spite of differences seen in stained slides, the MPO enzyme was positive in all of the patients, and no differences were seen between the two groups.

The average patient age and the duration of DM in the case group were more than those of the control group. No statistical differences in the type of DM and glycosylated hemoglobin (HbA1c) levels were found between the two groups. Body mass indexes (BMI) and PMN counts were higher in the case group. The most prevalent infections were in the skin and soft tissue, bones and joints, as well as chronic respiratory infections (TB), pneumonia, urinary infections, CNS infections, gastrointestinal and intra-abdominal infections, mucormycosis, and sepsis.

Conclusions: We found no correlation between MPO enzyme deficiency and age, sex, type or duration of DM, HbA1c levels and BMI.