By Caroline Song
A 44-year-old male double-lung transplant patient at Northwestern Memorial Hospital in Chicago, Illinois, passed away following complications 40 days after his procedure.
His death was brought on by hyperammonemia, a state of incredibly high levels of ammonia in the blood. High levels of ammonia lead to brain swelling, which causes the patient to slip into a coma and expire soon after.
A new study has found that a type of bacteria that usually resides in the urinary tract might be responsible for his untimely death, as well as for the deaths of many other lung transplant patients.
Normally, ammonia is excreted in urine so that blood levels remain very low. Unfortunately, when hyperammonemia does develop, it is disastrous: it is resistant to treatment and typically fatal. In the study, researchers linked the cause of hyerammonemia in lung transplant patients to the bacteria Mycoplasma hominid.
While the aforementioned patient did not test positive for M. hominis, he did test positive for Ureaplasma urealyticum, or U. urealyticulum. The microbe U. urealyticulum is similar to U. Parvum, and has been detected in other lung transplant recipients. In a separate study, 20 lung transplant recipients who tested negative for all three of these strains did not develop hyperammonemia.
Research shows a strong link between hyperammonemia and these three strains of microbes. Doctors recommend a combinatorial approach to treatment in order to prevent patients from developing resistance to the medication; the study found that the bacteria are already becoming resistant to Azithromycin.
While the link between the bacteria and hyperammonemia seems strong, researchers are not sure why transplant patients are so susceptible. It should be noted that Ureaplasma is found in about two thirds of the population, residing in the urinary tract where it assists with ammonia secretion. Cancer patients and transplant patients may be more susceptible to the bacterium and hyperammonemia due to their weakened immune systems. It is also possible that the donor organs could have been infected with the bacteria prior to transplantation.
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