LEGIONELLA - World Health Organization

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11.1.2 Staining Legionellae are Gram-negative bacteria with a thin cell wall, but stain poorly in the Gram procedure if neutral red or safranin is used as the counterstain. This characteristic is probably due to the composition of legionellae cell walls, which have large amounts of branched-chain cellular fatty acids and ubiquinones with side chains of 9–14 isoprene units (Moss et al., 1977; Lambert & Moss, 1989). Fatty acid and ubiquinone profiling have been used for identifying Legionella isolates to the level of species (Benson & Fields, 1998). On its own, Gram staining is inconclusive, even when samples are taken from normally sterile sites, such as transtracheal aspirates, lung biopsies or pleural fluids. Legionellae from these tissues appear as small, Gram-negative rods of varying sizes when counterstained with basic fuchsin. This effect is emphasized in legionellaeinfected tissues (Yu, 2000). Dieterle’s silver impregnation method is an alternative means of staining legionellae (Dieterle, 1927; Thomason et al., 1979). More sensitive and specific methods of identifying legionellae include antibody-coupled fluorescent dyes and immunoperoxidase staining. Further information on identifying legionellae species is given in Section 11.4. 11.2 Diagnostic methods The clinical symptoms of infection with Legionella are indistinguishable from the symptoms of other causes of pneumonia. Accurate diagnostic methods are therefore needed to identify Legionella, and to provide timely and appropriate therapy. To improve diagnosis, specialized laboratory tests must be carried out, by the clinical microbiology laboratory, on patients in a high-risk category. Tests for Legionnaires’ disease should ideally be performed on all patients with pneumonia at risk, including those who are seriously ill (with or without clinical features of legionellosis), and those for whom no alternative diagnosis prevails. In particular, tests for Legionnaires’ disease should be carried out on ill patients who are older than 40 years, immunosuppressed or unresponsive to beta-lactam antibiotics, or who might have been exposed to Legionella during an outbreak (Bartlett et al., 1998). Despite the availability of immunological and molecular genetic methods, diagnosis of Legionnaires’ disease is generally effective only for L. pneumophila serogroup 1. The sensitivity and specificity of methods for diagnosing and identifying other L. pneumophila serogroups and species of Legionella are far from perfect (Tartakovsky, 2001). Since 1995, diagnostic tests for legionellosis have changed significantly. The following laboratory methods are currently used for diagnosing Legionella infections (Stout, Rihs & Yu, 2003): • isolation of the bacterium on culture media • identification of the bacterium using paired serology • detection of antigens in urine <strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS
• detection of the bacterium in tissue or body fluids by immunofluorescent microscopy (e.g. direct immunofluorescence assay (DFA) testing) • detection of bacterial DNA using polymerase chain reaction (PCR). Table 11.1 compares the sensitivity, specificity and other characteristics of these methods. Use of culture or DFA techniques has decreased, and most cases of legionellosis are now identified through detection of urinary antigens. As a consequence of this shift, detection of L. pneumophila serogroup 1 is increasing, and all other serogroups are probably underdiagnosed. The highest number of cases of Legionnaires’ disease in travellers was reported by the European Surveillance Scheme for Travel Associated Legionnaires’ Disease in 1999. This reflects both greater surveillance and an increase in the use of urinary antigen for detecting L. pneumophila serogroup 1. Detection of urinary antigen was the most common method of detection (55% of cases; see Figure 11.1). The antigen detection test is substantially more sensitive for communityacquired and travel-associated Legionnaires’ disease than for nosocomial (health-care acquired) infection, because the tests are more sensitive for Pontiac L. pneumophila serogroup 1 than for non-Pontiac strains; the tests use monoclonal antibodies (MAb) MAb2 or Dresden MAb3/1. Pontiac strains cause the majority of community-acquired and travel-associated Legionnaires’ disease cases, but are significantly less common in nosocomially acquired cases. F gure . Method of d agnos s of travel-assoc ated Leg onna res’ d sease n Europe and year of onset of d sease Method of diagnosis by year of onset of disease 100% 800 Proportion 80% 60% 40% 20% 0% 1987 1988 Source: Information obtained from the European Working Group for Legionella Infections (EWGLI) 25 25 http://www.ewgli.org/ 1989 1990 1991 1992 1993 1994 1995 1996 <strong>LEGIONELLA</strong> AND THE PREVENTION OF LEGIONELLOSIS 1997 1998 1999 2000 2001 2002 Culture Serology (single high titre) Detection of urinary antigen Other Serology (fourfold rise) Number of clusters 2003 700 600 500 400 300 200 100 0 Number of clusters
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LEGIONELLA AND THE PREVENTION OF LE
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LEGIONELLA AND THE PREVENTION OF LE
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Foreword Legionellosis is a collect
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Contents Foreword . . . . . . . . .
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Chapter 5 Cooling towers and evapor
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Chapter 9 Disease surveillance and
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Tables Table 1.1 Main characteristi
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Figure 8.1 Visible biofilm on inter
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Acknowledgements The World Health O
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• John Newbold, Health and Safety
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Executive summary Legionellosis is
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• Health-care facilities — Chap
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Chapter 1 Legionellosis Britt Horne
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Legionnaires’ disease is often in
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1.1.2 Pontiac fever Symptoms Pontia
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Table . Extrapulmonary nfect ons ca
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Proteins produced by the body’s i
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Aspiration may occur in patients wi
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Table . R sk factors for Legionella
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In the outbreak of Legionnaires’
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Table . Potent al treatments for d
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1.4.2 Species and serogroups associ
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Other causes of infection In Europe
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The interaction of virulent legione
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1.5.2 Surface structures involved i
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1.5.4 Host defence The host defence
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Chapter 2 Ecology and environmental
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L. pneumophila is thermotolerant an
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2.2.3 Environmental factors and vir
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Figure 2.1 Biofilm formation Biofil
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2.4 Sources of Legionella infection
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Chapter 3 Approaches to risk manage
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Table . Cool ng tower outbreaks Fac
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Even when a source reaches a state
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The WSP should be prepared in conju
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Identify control measures Control m
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F gure . Dec mal reduct on t mes fo
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Method Advantages D sadvantages Dos
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Validate effectiveness of water saf
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• clear statements of responsibil
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Chapter 4 Potable water and in-buil
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The remainder of this chapter provi
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4.3.1 Document and describe the sys
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Construction materials — risk fac
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Where temperature controls (discuss
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4.4.2 Monitor control measures This
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Chapter 5 Cooling towers and evapor
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5.1.1 Cross-flow cooling towers As
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water treatments (including chemica
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5.3 System assessment This section
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Spray drift — risk factors Even w
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The section on control measures for
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• periodic or continuous bleed-of
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Box . Po nts to be noted when clean
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In certain circumstances, samples m
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Table . Example documentat on for m
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Chapter 6 Health-care facilities Ma
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For 1999 and 2000, a total of 384 c
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6.3 System assessment This section
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Table . Type of colon zat on of wat
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6.4.1 Identify control measures Thi
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6.5.1 Prepare management procedures
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Until the situation is under contro
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Chapter 7 Hotels and ships Roisin R
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F gure . Detected and reported case
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Table . Rev ew of outbreaks (more t
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7.2 Water safety plan overview WSPs
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The risk of legionellosis is increa
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Kingdom to 66% in Spain (Starlinger
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Agency, Legionella Section, United
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Given the complexity of distributio
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Chapter 8 Natural spas, hot tubs an
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Spas “Natural spa”, denotes fac
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Rare cases of Legionnaires’ disea
Page 149 and 150: Process step P pework Water n hot t
Page 151 and 152: Hosepipes may sometimes be used to
Page 153 and 154: Hot tubs that are not effectively d
Page 155 and 156: Nutrients — control measures Bath
Page 157 and 158: Various additives may also be used
Page 159 and 160: • descriptions of any significant
Page 161 and 162: Table . Examples of m crob olog cal
Page 163 and 164: Chapter 9 Disease surveillance and
Page 165 and 166: Exposure histories allow cases to b
Page 167 and 168: F gure . Invest gat ng a s ngle cas
Page 169 and 170: Box . (cont nued) Since the incepti
Page 171 and 172: Country United Kingdom All reported
Page 173 and 174: F gure . Annual reported cases, - 0
Page 175 and 176: Training opportunities Trainees in
Page 177 and 178: Box . Example of terms of reference
Page 179 and 180: ecause doing anything more could un
Page 181 and 182: 9.4 Case studies This section descr
Page 183 and 184: 9.4.4 Concrete batcher process on a
Page 185 and 186: Chapter 10 Regulatory aspects David
Page 187 and 188: • validation of the effectiveness
Page 189 and 190: • operating conditions, such as t
Page 191 and 192: 10.4.6 Outbreak investigation and n
Page 193 and 194: hot water (e.g. health-care facilit
Page 195 and 196: General prevent on Country DW Wp SB
Page 197 and 198: Country General prevent on DW Wp SB
Page 199: Chapter 11 Laboratory aspects of Le
Page 203 and 204: Method Sens t v ty (%) PCR • Rapi
Page 205 and 206: 11.2.2 Detecting Legionella antigen
Page 207 and 208: DFA has been used successfully with
Page 209 and 210: • Serologic testing can be used f
Page 211 and 212: Although not all strains can be rel
Page 213 and 214: Generally, any water source that ma
Page 215 and 216: During outbreak investigations, swa
Page 217 and 218: • other Legionella species that d
Page 219 and 220: Appendix 1 Example of a water syste
Page 221 and 222: Weekly water system check list Week
Page 223 and 224: Appendix 2 Example of a 2-week foll
Page 225 and 226: Travel Work/travel in the UK: ❑ Y
Page 227 and 228: Checklist of local places Health/sp
Page 229 and 230: Appendix 3 Example of a national su
Page 231 and 232: Strictly Confidential 2 Hospital Ac
Page 233 and 234: Glossary aerobic bacteria Bacteria
Page 235 and 236: health-care acquired Legionellosis
Page 237 and 238: surveillance The process of systema
Page 239 and 240: References Abu KY, Eisenstein BI, E
Page 241 and 242: Barbaree JM et al. (1987). Protocol
Page 243 and 244: Blatt SP et al. (1994). Legionnaire
Page 245 and 246: Byrne B, Swanson MS (1998). Express
Page 247 and 248: Crespi S (1993). Legionella y legio
Page 249 and 250: Edelstein PH (1982b). Comparative s
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Falguera M et al. (2001). Nonsevere
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Gaia V et al. (2003). Sequence-base
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Hayden RT et al. (2001). Direct det
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Ingram JG, Plouffe JF (1994). Dange
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Ko KS et al. (2003). Molecular evol
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Loret JF et al. (2003). Comparison
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McEvoy M et al. (2000). A cluster o
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Olaechea PM et al. (1996). A predic
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Regan CM et al. (2003). Outbreak of
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Schulze-Robbecke R, Rodder M, Exner
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Surman SB, Morton LHG, Keevil CW (1
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Tully M, Williams A, Fitzgeorge RB
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Welti M et al. (2003). Development
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