686
a faint pinkish tint remains. The slide is re-washed, before applying a methylene
blue counterstain for 30 s. Following re-washing with tap water, the slide is gently
blotted dry, and examined by oil-immersion (Doetsch 1981 ).
• Motility
In our experience, wet-preparations prepared from barely turbid suspensions are
most satisfactory when viewed by phase contrast microscopy at ×400
magnifi cation.
• Gliding motility
This may be assessed from the development of spreading growth on low-nutrient
(cytophaga) agar. It should be differentiated from locomotion by means of fl agella.
• Filterability through the pores of 0.45 μm pore size porosity fi lters
The ability of cells to pass through the pores of 0.45 μm pore size porosity fi lters
is indicative of the presence of L-forms and mycoplasmas. Thus, the bacterial suspension is fi ltered, and the fi ltrate applied to a suitable growth medium. Growth
within 7 days is indicative of fi lterability.
• The ability to grow only in fi sh cell cultures
Viruses and rickettsias are only capable of growth in suitable cell cultures.
• Aerobic or anaerobic requirements for growth
These are apparent after incubating inoculated media aerobically and
anaerobically.
• Catalase production
This is recorded by effervescence within 1 min from 3 % (v/v) hydrogen peroxide following application of a bacterial colony. Quite simply, the ‘young’ colony
may be scraped with a thin glass rod and transferred to a drop of hydrogen peroxide
on a glass slide.
• Fluorescent (fl uorescein) pigment production
This is assessed by the presence of a fl uorescent green pigment seen under ultraviolet light, after 7 days incubation on the medium of King et al. ( 1954 ).
• Growth at 10, 30 and 37 °C
Growth at 30 and 37 °C should be recorded within 72 h incubation on basal
medium. At 10 °C, the media should be retained for up to 14 days.
• Growth on 0 % and 6.5 % (w/v) sodium chloride and on 0.001 % (w/v) crystal
violet
This is reported after 7 and 14 days incubation on suitably modifi ed basal
medium.
13 Diagnosis
a faint pinkish tint remains. The slide is re-washed, before applying a methylene
blue counterstain for 30 s. Following re-washing with tap water, the slide is gently
blotted dry, and examined by oil-immersion (Doetsch 1981 ).
• Motility
In our experience, wet-preparations prepared from barely turbid suspensions are
most satisfactory when viewed by phase contrast microscopy at ×400
magnifi cation.
• Gliding motility
This may be assessed from the development of spreading growth on low-nutrient
(cytophaga) agar. It should be differentiated from locomotion by means of fl agella.
• Filterability through the pores of 0.45 μm pore size porosity fi lters
The ability of cells to pass through the pores of 0.45 μm pore size porosity fi lters
is indicative of the presence of L-forms and mycoplasmas. Thus, the bacterial suspension is fi ltered, and the fi ltrate applied to a suitable growth medium. Growth
within 7 days is indicative of fi lterability.
• The ability to grow only in fi sh cell cultures
Viruses and rickettsias are only capable of growth in suitable cell cultures.
• Aerobic or anaerobic requirements for growth
These are apparent after incubating inoculated media aerobically and
anaerobically.
• Catalase production
This is recorded by effervescence within 1 min from 3 % (v/v) hydrogen peroxide following application of a bacterial colony. Quite simply, the ‘young’ colony
may be scraped with a thin glass rod and transferred to a drop of hydrogen peroxide
on a glass slide.
• Fluorescent (fl uorescein) pigment production
This is assessed by the presence of a fl uorescent green pigment seen under ultraviolet light, after 7 days incubation on the medium of King et al. ( 1954 ).
• Growth at 10, 30 and 37 °C
Growth at 30 and 37 °C should be recorded within 72 h incubation on basal
medium. At 10 °C, the media should be retained for up to 14 days.
• Growth on 0 % and 6.5 % (w/v) sodium chloride and on 0.001 % (w/v) crystal
violet
This is reported after 7 and 14 days incubation on suitably modifi ed basal
medium.
13 Diagnosis