Bacterial contamination of 15 waiting room magazines.
| Magazine | Number of colonies on specified agar mediuma | ||
|---|---|---|---|
| SB (αβ-haemolytic) | BP (Staph. aureus) | MC (red colouration)b | |
| 1 | 62(0) | 3(0) | 94(0) |
| 2 | 14(5α)c | 7(0) | 3(0) |
| 3 | 5(0) | 0(0) | 8(4) |
| 4 | 20(0) | 12(0) | 10(4) |
| 5 | 8(1α)d | 0(0) | 4(1) |
| 6 | 13(1α)e | 1(0) | 5(0) |
| 7 | 8(0) | 1(0) | 6(3) |
| 8 | 19(10α)f | 0(0) | 5(0) |
| 9 | 8(0) | 1(0) | 15(0) |
| 10 | 4(0) | 0(0) | 2(0) |
| 11 | 115(1β)g | 5(1) | 91(28) |
| 12 | 14(0) | 3(0) | 4(0) |
| 13 | 22(0) | 1(0) | 10(2) |
| 14 | 6(0) | 0(0) | 14(1) |
| 15 | 7(0) | 15(0) | 3(0) |
↵aSB = sheep's blood (for the total aerobic viable count and haemolytic species); BP = Baird Parker (for the detection of Staphylococcus aureus); MC = MacConkey (red colonies may indicate enteric bacteria and/or enterococci). The following agar types gave no colonies: tryptone soya agar amended with 16 μg/ml penicillin G. The concentration of penicillin used, although a somewhat arbitrary choice, is the National Committee for Clinical Laboratory Standards (Wayne, PA) breakpoint for enterococci; tryptose sulphite cycloserine (for the detection of C. perfringens); Brilliant Green (primarily for the detection of Salmonella spp.); xylose lysine desoxycholate (for the detection of Salmonella spp. and other enteric bacteria).
↵bAll of the red colonies on MC plates were catalase- and Gram-positive cocci and were not investigated further.
↵c5 colonies of α-haemolytic Streptococcus mitis.
↵d1 colony of α-haemolytic Strep. sanguis.
↵e1 colony of α-haemolytic Strep. mitis.
↵f10 colonies of α-haemolytic Strep. sanguis and a Lancefield gr. D Leuconostoc sp.
↵gSingle colonies of methicillin-sensitive β-haemolytic Staph. aureus on blood and BP agars.