Is there any documentation on how methotrexate affects the local infection defense in the urinary t

Fråga: Is there any documentation on how methotrexate affects the local infection defense in the urinary tract? Does methotrexate have an influence on the immune system? Background: A patient with rheumatoid arthritis is suffering from a asymptomatic bacteriuria. The questioner now wants to start low-dose methotrexate treatment.

Sammanfattning: Methotrexate does affect in vivo immunological and inflammatory reactions; therefore, at least theoretically, low-dose methotrexate treatment might have an influence on the local infection defense in the urinary tract. There is one study that shows an increased occurrence of skin infections and respiratory tract infections among patients with rheumatoid arthritis undergoing low-dose pulse methotrexate therapy. The rate of urinary tract infections did not change. It was concluded that the increase of infections did not necessitate the withdrawal of methotrexate.

Svar: Methotrexate, a folic-acid antagonist, is regularly used by rheumatologists as a low-dose pulse therapy for the treatment of rheumatoid arthritis. Methotrexate affects in vitro and in vivo immunological and inflammatory reactions. The most clinically important finding is the inhibition of granulocyte function (1). Therefore, one of the concerns arising from low-dose methotrexate therapy for rheumatoid arthritis is a possible increase in the rate of infections. Several retrospective studies on the frequency of infections in patients with rheumatoid arthritis have shown that these patients, irrespective of treatment, are not more susceptible to common infections than control patients with osteoarthritis or soft tissue rheumatism.

During methotrexate therapy, chemotactic defects have been shown, but no significant changes in circulating T-cell population and T-cell activity have been found. On the basis of these findings, an increase in both cutaneous infections and prolonged recurrent infections with staphylococcus might be expected. It should be noted as well that gram-negative organisms and fungi could also be present. In a few cases, opportunistic infections have been reported in patients on methotrexate sometimes in combination with corticosteroids (2). We found a prospective study where they investigated the frequency, the type of infections and the use of antibiotics among patients with rheumatoid arthritis on methotrexate and patients with rheumatoid arthritis not on methotrexate. There was a significantly higher overall percentage of infections in the methotrexate group which was mainly due to increased occurrence of skin affections and respiratory tract infections. Antibiotics were used more frequently in the methotrexate group than in the control group. These differences were not related to duration of methotrexate therapy or use of prednisolone. The study concluded that there was no difference in the relative risk of getting urinary tract infections between the two groups. The increase of infections did not lead to serious illness nor to severe complications necessating the withdrawal of the medication (2).