Helicobacter pylori acquistion of metronidazole resistance by natural transformation in vitro

Table 1 Effect of time on transformants of H. pylori NCTC 11637

	6 h	12 h	18 h	24 h	30 h	36 h
Total bacteria	7.1 × 106	8.1 × 106	2.8 × 107	5.4 × 107	6.3 × 107	9.8 × 107
Transformants	20	370	1300	3200	3100	290
Frequencies	2.8 × 10-6	4.6 × 10-5	4.6 × 10-5	5.9 × 10-5	4.9 × 10-5	3.0 × 10-6

Table 2 Transformation of different strains of H. pylori

Recipient	Donor	Total bacteria	Transformants	Frequencies
H 1	H 38	1.8 × 108	43000	2.4 × 104
H 9		5.2 × 107	8900	1.7 × 104
H 11		9.3 × 108	No
H 13		8.4 × 107	4100	4.9 × 105
H 29		5.6 × 106	No
H 41		8.3 × 105	40	4.8 × 105
H 43		5.1 × 106	30	5.9 × 106
H 46		5.8 × 106	20	3.4 × 106
H 50		3.2 × 108	4500	1.4 × 105
H 53		3.5 × 107	320	9.1 × 106
H 62		3.9 × 105	No
H 68		8.8 × 107	740	8.4 × 106