Manual of basic techniques for a health laboratory - libdoc.who.int

256 Manual of basic techniques for a health laboratoryTable 8.1 Common causes of meningitisType of infectionBacterialProtozoalViralFungalSpecific organismNeisseria meningitidisStreptococcus spp., especiallyS. pneumoniaeStaphylococcus spp.Haemophilus influenzaeEscherichia coliListeria monocytogenesLeptospira spp.Mycobacterium tuberculosisTreponema pallidumPseudomonas spp.Plasmodium spp.CoxsackievirusesArbovirusesEchovirusesPoliovirusesMumps virusArenavirusesHuman herpesvirusesHepatitis virusesCandida albicansCryptococcus neoformans●●Work carefully and economically. Often only a small quantity of CSF is availablefor examination. The specimen is difficult to collect so do not waste any of it.The CSF may contain virulent organisms. Use pipettes plugged with non-absorbentcotton wool, or use a rubber safety bulb to draw up the fluid in the pipette. Neverpipette CSF by mouth.8.3.2 Direct examinationDescribe the appearance of the CSF specimen in the laboratory report.Clear CSFNormal CSF is clear and colourless (Fig. 8.3 (a)).Cloudy CSFIf pus is present, the CSF may appear slightly cloudy or greyish-white(Fig. 8.3 (b)).Fig. 8.3 Examining the appearance of CSFa: Clear (normal) CSF; b: cloudy CSF;c: bloodstained CSF.Bloodstained CSFIf blood is present, the CSF may appear cloudy and pink or reddish(Fig. 8.3 (c)). Blood is usually present in the CSF for one of tworeasons:— because of injury to blood vessels in the course of the lumbar puncture (inthis case there is more blood in tube 1 than in tube 2);— because of a subarachnoid haemorrhage (in this case both tubes are the samecolour).