Guidelines on the Prevention and Control of Tuberculosis in Ireland

More documents

Recommendations

Info

<strong>Guidelines</strong> on the Prevention and Control of Tuberculosis in Ireland 2010HSE/HPSCSputum specimensA direct relationship between mucopurulent sputum and positive results has been demonstrated. 125Therefore, patients should be instructed as to the proper method of sputum collection. Ideally a 5-10mlspecimen 122;126 collected early in the morning § § on three consecutive days (with a minimum of one earlymorning specimen) prior to the commencement of treatment, if possible, is required (or failing that, withinseven days of commencement of treatment). 123;126;127 Failure to isolate M. tuberculosis complex (MTC)from appropriately collected specimens from persons suspected of having a pulmonary diagnosis doesnot exclude a diagnosis of active TB. Depending on the clinical features and differential diagnosis, otherdiagnostic testing such as induced sputa, bronchoscopy lavage and biopsy should be considered beforemaking a presumptive diagnosis of culture negative TB. 128Bacteriological monitoringBacteriological monitoring after diagnosis may be required to assist with a decision to discontinueisolation. The period of time a patient on effective therapy takes to become non-infectious varies. Patientswho have unrecognised or inadequately treated drug-resistant TB may remain infectious for weeks ormonths. 129 Laboratories can be overwhelmed with specimens obtained for the purposes of demonstratingsmear conversion in smear positive patients. This can also contribute to an increase in false positive casesin the laboratory. It should be noted that beyond 12 weeks of treatment, 63% to 73% of patients withpersistently positive smear results have negative culture results. In the absence of MDR-TB and XDR-TB, the persistence of AFB in smears at the end of therapy is not necessarily a treatment failure. 130;131Laboratories should liaise with clinicians to develop a protocol for processing such specimens. Follow-upsputum specimens for smear and culture should be obtained monthly in patients with drug-susceptiblepulmonary disease. For patients with isoniazid- and rifampicin-susceptible TB there is no need to examinesputum monthly once culture conversion is documented (i.e. two negative cultures taken at least 2 to 4weeks apart). 77 It is recommended that identification and sensitivities are repeated in cases who are stillculture positive at ≥ two months. If the patient has isoniazid and/or rifampicin resistant TB, sputum culturesshould be examined monthly until the end of treatment. 77 Bacteriological monitoring i.e. culture at theend of treatment is strictly recommended in confirmed cases of TB to assess precisely that the patient hasbeen cured. Culture positive Mycobacterium tuberculosis complex (MTC) from each different site shouldundergo identification and sensitivity testing.Induced sputum and fibreoptic bronchoscopyHypertonic saline can be nebulised for induction of sputum. Bronchoscopy is the next best choice becausethis procedure provides additional material for study, washings, brushings and biopsy specimens. Inducedsputum has been shown to be as sensitive 132 or more sensitive 133;134 than bronchoscopy and is also cheaperto perform. Sputum induction in children has been shown to be safe and useful for microbiologicalconfirmation of TB in children and preferable to gastric lavage. 135 Where facilities permit it may bepreferable to gastric lavage. 135The bronchoscopy procedure may cause the patient to continue producing sputum for several days. Theuse of bronchoscopy in evaluating children with TB is not routine but it can provide useful information inselected cases. 136 (See section 8.1. Chapter 8 for contact tracing) (See section 6.5. Chapter 6 for infectionprevention and control). These samples should also be collected and examined. 110Gastric washingsGastric lavage may be necessary for those patients, particularly children, who cannot produce sputumeven with aerosol inhalation. Fasting early morning specimens are recommended to obtain sputumswallowed during sleep. 124 These specimens should be processed within four hours or neutralised withsodium carbonate or another buffered salt to a pH of 7.0. It has been suggested that for these reasonsgastric aspiration is best performed by experienced staff. 137 AFB smear testing is unreliable due to thehigh prevalence of atypical mycobacteria in gastric lavage. Culture should only be used for further clinicalmanagement.UrineUrine is an inappropriate specimen for the diagnosis of pulmonary TB. The diagnosis of renal TB,disseminated TB or TB in severely immunocompromised persons can be aided by the culture of 3 early______________________________________§ §Early morning sputum: sputum from the first productive cough in the day (after waking)-47-
<strong>Guidelines</strong> on the Prevention and Control of Tuberculosis in Ireland 2010HSE/HPSCmorning mid-stream urines each with a volume of 40-50ml. Smears of urine are usually negative and may notbe cost effective 110 or they may give unreliable results due to the presence of environmental mycobacteria thatmay be found in the lower urethra. 127 However, if examination of urine is restricted to those patients who areseverely immunocompromised, suspected of having renal or disseminated TB, or when haematuria or sterilepyuria has been demonstrated, the value of performing smears may be improved.FaecesFaecal specimens are largely used in the detection of Mycobacterium avium complex (MAC) from theintestinal tract of patients with HIV/AIDS, in conjunction with specimens from other sites. Interpretation mayalso be difficult due to the presence of saprophytic AFB frequently present in faeces samples. 127Cerebrospinal fluidCerebrospinal fluid (CSF) should be examined for protein, glucose and white cell count and differential.Lymphocytosis together with a low glucose and high protein are typical of TB meningitis. The volume of CSFis critical and a minimum of 5ml 110 but up to 10ml is ideally required 126;138 provided it is medically safe to obtainthis volume. Studies should be undertaken prior to the administration of anti-tuberculous chemotherapy.There is a low yield of approximately 40% and if feasible it may be worthwhile to perform repeat cultures.Blood cultureInfection with Mycobacterium species became increasingly common as the incidence of HIV infection andAIDS increased. Up to 63% of HIV/AIDS patients with active TB disease have positive blood cultures. 139 Bloodculture should be the first step in the routine evaluation of HIV positive patients with suspected TB. 140TissueWhen non-invasive procedures have failed to provide a diagnosis, invasive procedures to obtain specimensfrom lung, pericardium, lymph nodes, bones and joints, bowel, etc. should be considered. 110 Specimenssubmitted in formalin are not suitable for microbiological smear and culture. In patients withhaematogenous or disseminated disease, bone marrow biopsy, lung biopsy and liver biopsy for histologicalexamination and culture can be useful. 110 Tissue is preferable to necrotic material or pus, as the lattercontain free fatty acids that are toxic to mycobacteria. 127 A caseous portion should be selected if possibleas the majority of organisms will be found in the periphery of a caseous lesion. 126 Pleural biopsy showsgranulomatous inflammation in approximately 60% of patients. 110 Minute amounts of biopsy material may beimmersed in a small amount of sterile saline to stop them drying out.Body fluidsPleural, peritoneal, synovial and pericardial fluids should be aseptically collected by aspiration or duringsurgical procedures and transported to the microbiology laboratory immediately. It should be noted thatdetection of AFB in smears of culture positive pleural fluids is extremely low at between 0 to 1% 141 and thesensitivity of nucleic acid amplification tests (NAAT) has been shown to be in the order of only 27 to 32% usingfully commercially available methods (see section on nucleic acid amplification tests). 1424.3 Specimen ProcessingMicroscopyAcid-fast microscopy is “the microscopic examination of stained smears for the presence of organismsthat retain the primary stain when the smear is decolourised with an acid alcohol solution”. Fluorescencestaining, 143 of clinical material using auramine-o or auramine-rhodamine is to be preferred over Ziehl-Neilson(ZN) staining because it is quicker and easier to read, 124;144;145 whilst the ZN is more appropriate in determiningmicroscopic morphology of bacilli in positive TB cultures. Factors affecting the sensitivity of smears are manyand include the staining technique, centrifugal force, decontamination technique used, the infecting species,reader experience and the prevalence of disease in the population being tested. 110;145;146Key points relating to microscopy:• Results should be available within one working day• Microscopy of clinical material (by either Auramine or Ziehl-Neilson (ZN)) is the easiest, most costeffectiveand rapid procedure for detecting mycobacteria-48-
Page 2 and 3:
Guidelines on the
Page 4 and 5:
Guidelines on the
Page 6 and 7:
Guidelines on the
Page 8 and 9:
Guidelines on the
Page 10 and 11:
Guidelines on the
Page 12 and 13:
Guidelines on the
Page 14 and 15:
Guidelines on the
Page 16 and 17: Guidelines on the
Page 54 and 55: BGuidelines on the
Page 70 and 71: 1♦Guidelines on
Page 98 and 99: Figure 6.1Patient placement for Pul
Page 116 and 117:
Guidelines on the
Page 118 and 119:
Guidelines on the
Page 120 and 121:
Guidelines on the
Page 122 and 123:
Guidelines on the
Page 124 and 125:
Guidelines on the
Page 126 and 127:
Guidelines on the
Page 128 and 129:
Guidelines on the
Page 130 and 131:
Guidelines on the
Page 132 and 133:
Guidelines on the
Page 134 and 135:
Guidelines on the
Page 136 and 137:
Guidelines on the
Page 138 and 139:
Guidelines on the
Page 140 and 141:
Guidelines on the
Page 142 and 143:
Guidelines on the
Page 144 and 145:
Guidelines on the
Page 146 and 147:
Guidelines on the
Page 148 and 149:
Guidelines on the
Page 150 and 151:
Guidelines on the
Page 152 and 153:
Guidelines on the
Page 154 and 155:
Guidelines on the
Page 156 and 157:
Guidelines on the
Page 158 and 159:
Guidelines on the
Page 160 and 161:
Guidelines on the
Page 162 and 163:
Guidelines on the
Page 164 and 165:
Guidelines on the
Page 166 and 167:
Guidelines on the
Page 168 and 169:
Guidelines on the
Page 170 and 171:
Guidelines on the
Page 172 and 173:
Guidelines on the
Page 174 and 175:
Guidelines on the
Page 176 and 177:
Guidelines on the
Page 178 and 179:
Guidelines on the
Page 180 and 181:
Guidelines on the
Page 182 and 183:
Guidelines on the
Page 184 and 185:
Guidelines on the
Page 186 and 187:
Guidelines on the
Page 188 and 189:
Guidelines on the
Page 190 and 191:
Guidelines on the
Page 192 and 193:
Guidelines on the
Page 194 and 195:
Guidelines on the
Page 196 and 197:
Guidelines on the
Page 198 and 199:
Guidelines on the
Page 200 and 201:
Guidelines on the
Page 202 and 203:
Guidelines on the
Page 204 and 205:
Guidelines on the
Page 206 and 207:
Guidelines on the
Page 208 and 209:
Guidelines on the
Page 210 and 211:
Guidelines on the
Page 212 and 213:
Guidelines on the
Page 214 and 215:
Guidelines on the
Page 216 and 217:
Guidelines on the
Page 218:
25-27 Middle Gardiner Street Dublin
show all

Guidelines on the Prevention and Control of Tuberculosis in Ireland

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?