Raj,
While your dad is in the hospital his blood counts will probably be monitored daily. I'm not sure why they think an infection is a sign of progression of MDS but it's certainly a common MDS symptom since a low white count makes patients more susceptible to infections.
The measure used to judge the risk of infection is the
Absolute Neutrophil Count (ANC), which is computed from the white cell count (WBC) and a white cell analysis called a "differential." You might want to ask if your dad's ANC has been computed.