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139:(destruction of red blood cells) on the agar plate. In colonial morphology, hemolysis is classified into three types: alpha-, beta-, and gamma-hemolysis. In alpha-hemolysis, the blood is partially digested, causing the area around the colony to turn green. In beta-hemolysis, the organism digests the blood completely, leaving a clear area around each colony. Organisms that do not produce hemolysis are referred to as gamma-hemolytic.
49:. Examining colonial morphology is the first step in the identification of an unknown microbe. The systematic assessment of the colonies' appearance, focusing on aspects like size, shape, colour, opacity, and consistency, provides clues to the identity of the organism, allowing microbiologists to select appropriate tests to provide a definitive identification.
73:
to encourage microbial growth. Because the appearance of microbial colonies changes as they grow, colonial morphology is examined at a specific time after the plate is inoculated. Usually, the plate is read at 18–24 hours post-inoculation, but times may differ for slower-growing organisms like fungi.
350:
Colonial morphology serves as the first step in the identification of microbial species from clinical samples. Based on the visual appearance of the colonies, microbiologists can narrow down the list of possible organisms, allowing them to select appropriate tests to provide a definitive diagnosis.
95:
species are translucent. The overall shape of the colony may be characterized as circular, irregular, or punctiform (like pinpoints). The vertical growth or elevation of the colony, another identifying characteristic, is assessed by tilting the agar plate to the side and is denoted as flat, raised,
427:
are increasingly used to identify microorganisms in clinical laboratories, colonial morphology remains useful to distinguish potential pathogens, which must be identified, from normal flora, for which definitive identification is unnecessary, and to confirm identification when automated techniques
152:
The odour of a culture is sometimes considered part of colonial morphology. While intentionally smelling microbial cultures is not advised, some organisms produce distinctive odours that can be detected during routine examination of the culture. Among these are
288:
237:
96:
convex, pulvinate (very convex), umbilicate (having a depression in the centre) or umbonate (having a bump in the centre). The edge of the colony may be separately described using terms like smooth, rough, irregular and filamentous.
109:
Consistency is examined by physically manipulating the colony with a sterile instrument. It is described using terms like brittle, creamy, sticky and dry. Staphylococci are considered to have a creamy consistency, while some
220:
753:
Bae, Euiwon; Kim, Huisung; Rajwa, Bartek; Thomas, John G.; Robinson, J. Paul (2015). "Current status and future prospects of using advanced computer-based methods to study bacterial colonial morphology".
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378:
Observation of hemolysis is useful in the presumptive identification of bacteria, especially streptococci, which are classified on the basis of their hemolytic reactions. For example,
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1016:
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The microbiologist examines the appearance of the colony, noting specific features such as size, colour, shape, consistency, and opacity. A
1194:
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299:: red pigmentation: although considered characteristic of the species, only about 10% of specimens produce this pigment
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121:
571:
P. J. Quinn; B. K. Markey; F. C. Leonard; P. Hartigan; S. Fanning; E. S. Fitzpatrick (7 October 2011).
412:
1139:
1290:
1241:
1057:
949:
924:
515:
Linné & Ringsrud's
Clinical Laboratory Science: Concepts, Procedures, and Clinical Applications
394:
261:
174:
Other distinctive features of colonial morphology include motility and the production of pigments.
136:
70:
231:: large opaque, round, creamy, white to yellowish colonies displaying beta-hemolysis on blood agar
1089:
663:
Luis M. de la Maza; Marie T. Pezzlo; Cassiana E. Bittencourt; Ellena M. Peterson (16 June 2020).
141:
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25:
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The opacity of a microbial colony can be described as transparent, translucent, or opaque.
149:, is noteworthy for producing a "double zone" of both complete and incomplete hemolysis.
8:
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is notable for its filamentous appearance, which is sometimes described as resembling
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species, exhibit concentric waves of growth extending from the inoculation point.
65:
When a specimen arrives in the microbiology laboratory, it is inoculated into an
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840:. Oklahoma City, United States: University of Oklahoma Health Sciences Center
775:
389:
356:
91:
86:
1159:
1104:
1079:
783:
385:
265:: small colonies with raised edges displaying alpha-hemolysis on blood agar
146:
805:
Karin C. VanMeter; Robert J. Hubert; William G. VanMeter (7 August 2013).
1397:
1114:
193:
171:, whose scent is alternately described as putrid or like chocolate cake.
117:
1373:
1069:
478:
Connie R. Mahon; Donald C. Lehman; George
Manuselis (18 January 2018).
403:
132:
66:
46:
838:
Streptococcus pyogenes : Basic
Biology to Clinical Manifestations
1295:
1154:
699:
Karen C. Carroll; Janet S. Butel; Stephen A. Morse (12 August 2015).
424:
399:
183:
179:
112:
75:
337:: granular colonies with a white edge and central black pigmentation
248:: small translucent colonies displaying beta-hemolysis on blood agar
1271:
1179:
1119:
1096:
351:
For example, if a microbiologist observes colonies that resemble a
635:
608:
1390:
944:
103:
42:
543:
186:, which give the colonies a greenish sheen. Some specimens of
1343:
1305:
1174:
547:
Koneman's Color Atlas and
Textbook of Diagnostic Microbiology
832:
Androulla, Efstratiou; Theresa, Lamagni (10 February 2016).
135:, they may digest the blood in the medium, causing visible
702:
Jawetz
Melnick & Adelbergs Medical Microbiology 27 E
914:
636:
Apurba Sankar Sastry; Bhat
Sandhya K (20 August 2017).
609:
Michael J. Leboffe; Burton E. Pierce (1 January 2012).
725:
612:
511:
798:
416:, part of the normal skin flora and an occasional
406:, displays alpha-hemolysis. The highly pathogenic
752:
1430:
831:
320:colonies displaying beta-hemolysis on blood agar
82:may be used to view colonies in greater detail.
61:Some terms used to describe colonial morphology
865:—the microscopic appearance of bacterial cells
564:
900:
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694:
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690:
688:
686:
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604:
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598:
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574:Veterinary Microbiology and Microbial Disease
507:
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165:, which is said to smell like old socks; and
808:Microbiology for the Healthcare Professional
719:
539:
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23:Colonial morphology of various specimens of
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410:classically displays beta-hemolysis, while
907:
893:
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683:
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498:
629:
544:Gary W. Procop; Elmer W. Koneman (2017).
532:
359:to confirm that it belongs to the genus
211:Colonial morphology of selected organisms
131:When certain microorganisms are grown on
128:often have a slimy (mucoid) consistency.
124:are typically dry. Bacteria that produce
834:"Epidemiology of Streptococcus pyogenes"
438:
56:
18:
756:Expert Review of Anti-infective Therapy
1431:
371:or a more pathogenic species, such as
888:
192:produce an orange-red pigment called
639:Essentials of Practical Microbiology
116:species are sticky, and colonies of
1200:Oxidative/fermentation glucose test
666:Color Atlas of Medical Bacteriology
481:Textbook of Diagnostic Microbiology
423:Although automated techniques like
37:refers to the visual appearance of
13:
282:: swarming behaviour on blood agar
14:
1455:
1326:Antibiotic susceptibility testing
1133:biochemical and immunologic tests
880:American Society for Microbiology
869:
392:, displays beta-hemolysis, while
369:coagulase-negative staphylococcus
345:
16:Examination of microbial colonies
1354:Minimum inhibitory concentration
1046:Manual testing: basic techniques
726:M. R. Adams; M. O. Moss (2008).
420:, does so weakly or not at all.
325:
304:
287:
270:
253:
236:
219:
159:, which has a grape-like scent;
876:Colony Morphology Image Gallery
863:Bacterial cellular morphologies
89:are usually opaque, while many
1262:Novobiocin susceptibility test
1252:Bacitracin susceptibility test
732:. Royal Society of Chemistry.
1:
1145:Amino acid decarboxylase test
768:10.1586/14787210.2016.1122524
615:. Morton Publishing Company.
431:
367:to determine whether it is a
1257:Optochin susceptibility test
1220:Sulfide indole motility test
1205:Phenylalanine deaminase test
811:. Elsevier Health Sciences.
512:Mary Louise Turgeon (2016).
484:. Elsevier Health Sciences.
355:species, they may perform a
52:
7:
856:
428:give inconclusive results.
122:beta-hemolytic streptococci
10:
1460:
413:Staphylococcus epidermidis
1366:
1324:
1301:Polymerase chain reaction
1280:
1130:
1045:
1034:
1004:
963:
937:
923:
705:. McGraw-Hill Education.
669:. John Wiley & Sons.
577:. John Wiley & Sons.
550:. Wolters Kluwer Health.
1291:Analytical profile index
395:Streptococcus pneumoniae
262:Streptococcus pneumoniae
29:, including mucoid types
1439:Microbiology techniques
142:Clostridium perfringens
1225:Triple sugar iron test
418:opportunistic pathogen
381:Streptococcus pyogenes
245:Streptococcus pyogenes
178:produces the pigments
176:Pseudomonas aeruginosa
156:Pseudomonas aeruginosa
62:
30:
26:Pseudomonas aeruginosa
1283:point-of-care testing
964:Cultures by body site
917:clinical microbiology
228:Staphylococcus aureus
162:Staphylococcus aureus
60:
22:
1242:Voges–Proskauer test
1150:Bile solubility test
1005:Cultures by organism
938:Isolation techniques
1349:McFarland standards
1339:Disk diffusion test
1334:Beta-lactamase test
1267:Lancefield grouping
1247:X and V factor test
1215:Salt tolerance test
1090:Ziehl–Neelsen stain
1053:Colonial morphology
296:Serratia marcescens
189:Serratia marcescens
35:colonial morphology
1444:Microbiology terms
1418:Inoculation needle
642:. JP Medical Ltd.
518:. Elsevier Mosby.
398:, which can cause
196:. Organisms with
99:Bacillus anthracis
63:
31:
1426:
1425:
1403:Biosafety cabinet
1362:
1361:
1210:Reverse CAMP test
1030:
1029:
1012:Bacterial culture
818:978-0-323-27702-0
739:978-0-85404-284-5
729:Food Microbiology
712:978-0-07-182503-0
676:978-1-68367-035-3
649:978-93-5270-185-8
622:978-1-61731-007-2
584:978-1-118-25116-4
557:978-1-4511-1659-5
525:978-0-323-22545-8
491:978-0-323-48212-7
334:Aspergillus niger
198:swarming motility
168:Proteus mirabilis
69:and placed in an
33:In microbiology,
1451:
1413:Inoculation loop
1311:Rapid strep test
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80:magnifying glass
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1185:Methyl red test
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1131:Manual testing:
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1085:India ink stain
1075:Acid-fast stain
1038:
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976:Genital culture
959:
955:Selective media
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1165:Coagulase test
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1036:Identification
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1017:Fungal culture
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986:Throat culture
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870:External links
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762:(2): 207–218.
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365:coagulase test
361:Staphylococcus
353:Staphylococcus
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346:Interpretation
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318:"ground-glass"
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996:Wound culture
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971:Blood culture
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390:scarlet fever
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120:bacteria and
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92:Streptococcus
88:
87:Staphylococci
83:
81:
77:
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68:
59:
50:
48:
44:
40:
36:
28:
27:
21:
1190:Nitrite test
1160:Citrate test
1101:Rapid tests
1080:Giemsa stain
1052:
950:Streak plate
842:. Retrieved
837:
827:
807:
800:
759:
755:
748:
728:
721:
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665:
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386:strep throat
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147:gas gangrene
140:
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111:
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90:
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64:
34:
32:
24:
1398:Durham tube
1230:Urease test
1039:and testing
279:Proteus sp.
194:prodigiosin
118:diphtheroid
1433:Categories
1374:Agar plate
1170:DNAse test
1070:Gram stain
432:References
404:meningitis
133:blood agar
67:agar plate
47:agar plate
1408:Incubator
1367:Equipment
1296:MALDI-TOF
1195:ONPG test
1155:CAMP test
1058:Hemolysis
925:Isolation
776:1478-7210
425:MALDI-TOF
408:S. aureus
400:pneumonia
373:S. aureus
184:pyoverdin
180:pyocyanin
137:hemolysis
113:Neisseria
106:'s head.
76:hand lens
71:incubator
53:Procedure
39:bacterial
1272:RPR test
1180:KOH test
1140:ALA test
1110:Catalase
1097:Wet prep
1065:Staining
857:See also
792:38205341
784:26582139
363:, and a
126:capsules
1391:Gas-pak
1105:Oxidase
945:Asepsis
930:culture
878:at the
844:6 March
203:Proteus
200:, like
1115:Indole
815:
790:
782:
774:
736:
709:
673:
646:
619:
581:
554:
522:
488:
104:Medusa
45:on an
1344:Etest
1306:VITEK
1235:rapid
1175:IMViC
788:S2CID
928:and
846:2020
813:ISBN
780:PMID
772:ISSN
734:ISBN
707:ISBN
671:ISBN
644:ISBN
617:ISBN
579:ISBN
552:ISBN
520:ISBN
486:ISBN
402:and
388:and
182:and
1120:PYR
764:doi
78:or
41:or
1435::
836:.
786:.
778:.
770:.
760:14
758:.
685:^
593:^
534:^
500:^
440:^
375:.
316::
908:e
901:t
894:v
848:.
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