Diphtheria laboratory findings: Difference between revisions
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{{Diphtheria}} | {{Diphtheria}} | ||
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==Overview== | ==Overview== | ||
A presumptive diagnosis of [[diphtheria]] is usually made based on an observation of clinical features. A definitive diagnosis is made by growing the specific [[Corynebacterium]] species on special cultures from the [[respiratory]] tract secretions or [[cutaneous]] lesions. Other tests include [[toxin]] detection via various methods. | |||
==Laboratory Findings== | |||
A presumptive diagnosis of [[diphtheria]] is usually made based on clinical features. A definitive diagnosis can be made by growing the specific [[Corynebacterium]] species on special cultures from the [[respiratory]] tract secretions or [[cutaneous]] lesions. Other tests include toxin detection via various methods.<ref name="pmid10657205">{{cite journal |vauthors=Efstratiou A, Engler KH, Mazurova IK, Glushkevich T, Vuopio-Varkila J, Popovic T |title=Current approaches to the laboratory diagnosis of diphtheria |journal=J. Infect. Dis. |volume=181 Suppl 1 |issue= |pages=S138–45 |year=2000 |pmid=10657205 |doi=10.1086/315552 |url=}}</ref><ref name="pmid1740514">{{cite journal |vauthors=Colman G, Weaver E, Efstratiou A |title=Screening tests for pathogenic corynebacteria |journal=J. Clin. Pathol. |volume=45 |issue=1 |pages=46–8 |year=1992 |pmid=1740514 |pmc=495813 |doi= |url=}}</ref><ref name="pmid18017268">{{cite journal |vauthors=Widelock D |title=Laboratory Diagnosis of Diphtheria |journal=Am J Public Health Nations Health |volume=41 |issue=1 |pages=120 |year=1951 |pmid=18017268 |pmc=1525936 |doi= |url=}}</ref> | |||
===Culture and Staining=== | |||
The diagnosis of [[diphtheria]] is made by culture and special staining for the different [[Corynebacterium]] species from [[respiratory]] tract secretions or [[cutaneous]] lesions:<ref name="pmid10657205">{{cite journal |vauthors=Efstratiou A, Engler KH, Mazurova IK, Glushkevich T, Vuopio-Varkila J, Popovic T |title=Current approaches to the laboratory diagnosis of diphtheria |journal=J. Infect. Dis. |volume=181 Suppl 1 |issue= |pages=S138–45 |year=2000 |pmid=10657205 |doi=10.1086/315552 |url=}}</ref><ref name="pmid1740514">{{cite journal |vauthors=Colman G, Weaver E, Efstratiou A |title=Screening tests for pathogenic corynebacteria |journal=J. Clin. Pathol. |volume=45 |issue=1 |pages=46–8 |year=1992 |pmid=1740514 |pmc=495813 |doi= |url=}}</ref><ref name="pmid18017268">{{cite journal |vauthors=Widelock D |title=Laboratory Diagnosis of Diphtheria |journal=Am J Public Health Nations Health |volume=41 |issue=1 |pages=120 |year=1951 |pmid=18017268 |pmc=1525936 |doi= |url=}}</ref><ref>{{cite book |last=Mandell |first=Gerald L. |date=1985 |title=Principles and Practice of Infectious Disease |url= |location=USA |publisher=John Wiley & Sons |page=1171 |isbn=0471876437}}</ref> | |||
*Gram stain: Gram positive rods in a distribution that is said to resemble Chinese characters | |||
*Tellurite stain: Gray-black colonies | |||
*Tindale: Black colonies with halos around it and an associated garlic odor | |||
*Loffler medium: Metachromatic staining | |||
===Biochemical Tests=== | |||
Most species of [[Corynebacterium]] are [[catalase]]-positive, [[urea]]-negative, [[nitrate]]-positive, pyrazinamidase-negative and cystinase-positive.<ref name="pmid10657205">{{cite journal |vauthors=Efstratiou A, Engler KH, Mazurova IK, Glushkevich T, Vuopio-Varkila J, Popovic T |title=Current approaches to the laboratory diagnosis of diphtheria |journal=J. Infect. Dis. |volume=181 Suppl 1 |issue= |pages=S138–45 |year=2000 |pmid=10657205 |doi=10.1086/315552 |url=}}</ref> | |||
===Toxin Detection=== | |||
The toxin for '''''[[Corynebacterium]] [[diphtheria]]''''' can be detected through a variety of methods, which include:<ref name="pmid10657205">{{cite journal |vauthors=Efstratiou A, Engler KH, Mazurova IK, Glushkevich T, Vuopio-Varkila J, Popovic T |title=Current approaches to the laboratory diagnosis of diphtheria |journal=J. Infect. Dis. |volume=181 Suppl 1 |issue= |pages=S138–45 |year=2000 |pmid=10657205 |doi=10.1086/315552 |url=}}</ref><ref name="pmid1740514">{{cite journal |vauthors=Colman G, Weaver E, Efstratiou A |title=Screening tests for pathogenic corynebacteria |journal=J. Clin. Pathol. |volume=45 |issue=1 |pages=46–8 |year=1992 |pmid=1740514 |pmc=495813 |doi= |url=}}</ref> | |||
*Elek's test | |||
*[[PCR]]: a positive assay for the [[diphtheria]] toxin gene is not confirmatory, but rather suggests that '''''[[Corynebacterium]] [[diphtheria]]''''' is the causative agent. However, a negative assay does rule it out. | |||
*[[Enzyme immunoassay]] (EIA) | |||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Dima Nimri, M.D. [2]
Overview
A presumptive diagnosis of diphtheria is usually made based on an observation of clinical features. A definitive diagnosis is made by growing the specific Corynebacterium species on special cultures from the respiratory tract secretions or cutaneous lesions. Other tests include toxin detection via various methods.
Laboratory Findings
A presumptive diagnosis of diphtheria is usually made based on clinical features. A definitive diagnosis can be made by growing the specific Corynebacterium species on special cultures from the respiratory tract secretions or cutaneous lesions. Other tests include toxin detection via various methods.[1][2][3]
Culture and Staining
The diagnosis of diphtheria is made by culture and special staining for the different Corynebacterium species from respiratory tract secretions or cutaneous lesions:[1][2][3][4]
- Gram stain: Gram positive rods in a distribution that is said to resemble Chinese characters
- Tellurite stain: Gray-black colonies
- Tindale: Black colonies with halos around it and an associated garlic odor
- Loffler medium: Metachromatic staining
Biochemical Tests
Most species of Corynebacterium are catalase-positive, urea-negative, nitrate-positive, pyrazinamidase-negative and cystinase-positive.[1]
Toxin Detection
The toxin for Corynebacterium diphtheria can be detected through a variety of methods, which include:[1][2]
- Elek's test
- PCR: a positive assay for the diphtheria toxin gene is not confirmatory, but rather suggests that Corynebacterium diphtheria is the causative agent. However, a negative assay does rule it out.
- Enzyme immunoassay (EIA)
References
- ↑ 1.0 1.1 1.2 1.3 Efstratiou A, Engler KH, Mazurova IK, Glushkevich T, Vuopio-Varkila J, Popovic T (2000). "Current approaches to the laboratory diagnosis of diphtheria". J. Infect. Dis. 181 Suppl 1: S138–45. doi:10.1086/315552. PMID 10657205.
- ↑ 2.0 2.1 2.2 Colman G, Weaver E, Efstratiou A (1992). "Screening tests for pathogenic corynebacteria". J. Clin. Pathol. 45 (1): 46–8. PMC 495813. PMID 1740514.
- ↑ 3.0 3.1 Widelock D (1951). "Laboratory Diagnosis of Diphtheria". Am J Public Health Nations Health. 41 (1): 120. PMC 1525936. PMID 18017268.
- ↑ Mandell, Gerald L. (1985). Principles and Practice of Infectious Disease. USA: John Wiley & Sons. p. 1171. ISBN 0471876437.