Phage-typing and drug-resistance patterns as tools in mycobacterial epidemiology

Phage-typing by itself was not sufficient to delineate the boundaries of a mini-epidemic of tuberculosis in upstate New York. Drug-resistance patterns were needed as well. In a small upstate community, 79% of 14 isolates tested were resistant to one or more of the antituberculosis drugs. Of 15 isolates with phage types determined, 47% were type 1(13), 27% were type 7(7, 13), and 27% were type 1(7, 12, 13). By combining phage-typing and sensitivity testing, we were able to demonstrate that 4 or possibly 5 of the 7 phage-type 1(13) strains are epidemiologically related.