Drug resistant virus as common in HIV-infected infants as in newly infected adults

Researchers in New York are suggesting that all infants born with HIV infection should have resistance testing performed “at the earliest opportunity,” after they found that more than 12% of all HIV-infected infants born in 1998 and 1999 had HIV mutations associated with resistance to at least one antiretroviral. This is similar to the prevalence of drug resistance for newly infected adults.

In total 120 infants were found to be HIV-infected throughout New York State during 1998-99, of which 91 had blood samples available for genotypic testing. Seven had at least one NRTI-associated mutation, three had NNRTI-associated mutations, three had at least one PI-associated mutation and two had multiclass resistant HIV.

Surprisingly, the mother’s exposure to antiretrovirals around the time immediately preceding, during or following birth (the perinatal period) was not found to be a significant factor for the appearance of resistant strains of HIV.

Although six of the eleven infants with drug resistance mutations had perinatal exposure to antiretrovirals which corresponded, at least partially, to the mother’s regimen, the remaining five infants had no recorded antiretroviral exposure during the perinatal period.

The researchers say that three possibilities may exist to explain this: drug-resistant virus emerged prior to pregnancy; the mother was infected with a drug-resistant virus prior to or during pregnancy or the mutations have arisen spontaneously.

However, since there is evidence that the presence of drug resistance mutations in perinatally infected children can affect clinical progression, in the absence of preventative measures, resistance testing appears to be the best option at this point for all newly-infected infants.