One of the most important reasons for treating GABHS pharyngitis strep throat is to prevent rheumatic fever. Poststreptococcal acute glomerulonephritis Rapidly Progressive Glomerulonephritis RPGN Rapidly progressive glomerulonephritis is acute nephritic syndrome accompanied by microscopic glomerular crescent formation with progression to renal failure within weeks to months.
It is most common among children, occurring 1 to 3 weeks after infection. Nearly all children, but somewhat fewer adults, recover without permanent renal damage. PANDAS syndrome pediatric autoimmune neuropsychiatric disorder associated with group A streptococci refers to a subset of obsessive disorders or tic disorders in children that is thought to be exacerbated by GABHS infection. Certain forms of psoriasis Psoriasis Psoriasis is an inflammatory disease that manifests most commonly as well-circumscribed, erythematous papules and plaques covered with silvery scales.
Multiple factors contribute, including Rapid antigen-detection tests that can detect GABHS directly from throat swabs are available ie, for point-of-care use.
Many tests use enzyme immunoassay, but more recently, tests using optical immunoassay have become available. Thus, positive results can establish the diagnosis, but negative results, at least in children, should be confirmed by culture.
Because streptococcal pharyngitis is less common among adults and adults are unlikely to have poststreptococcal complications, many clinicians do not confirm a negative rapid screening result in adults by culture unless use of a macrolide is being considered; in such cases, culture with susceptibility testing to detect macrolide resistance should be done.
Demonstrating antistreptococcal antibodies in serum during convalescence provides only indirect evidence of infection. Antistreptococcal antibody tests are not useful in diagnosing acute GABHS infection because antibody first develops several weeks after GABHS infection begins and a single high antibody titer is more likely to reflect a long antecedent infection.
Antibodies are most useful in diagnosis of poststreptococcal diseases, such as rheumatic fever and glomerulonephritis. Both titers may remain elevated for several months, even after uncomplicated infections. A single titer greater than the upper limit of normal suggests an antecedent streptococcal infection or high streptococcal endemicity in the community. For completeness in difficult cases, any one of the other tests antihyaluronidase, antinicotinamide adenine dinucleotidase, antistreptokinase can also be used.
Penicillin given within the first 5 days for symptomatic streptococcal pharyngitis may delay the appearance and decrease the magnitude of the ASO response. Patients with streptococcal pyoderma usually do not have a significant ASO response but may have a response to other antigens ie, anti-DNAase, antihyaluronidase.
Antibiotics shorten the course in young children, especially those with scarlet fever, but have only modest effect on symptoms in adolescents and adults. However, antibiotics help prevent local suppurative complications eg, peritonsillar abscess , otitis media, and rheumatic fever. However, some streptococcal strains appear to have in vitro tolerance to penicillin ie, significantly decreased bactericidal effect of penicillin ; the clinical significance of such strains is unclear.
A single injection of benzathine penicillin G , units IM for small children 27 kg or 1. Oral drugs may be used if the patient can be trusted to maintain the regimen for the required 10 days. Choices include. Oral narrow-spectrum cephalosporins eg, cephalexin , cefadroxil are also effective and can be used unless patients have an anaphylactic reaction to penicillin.
Azithromycin can be used for a 5-day course of therapy, although macrolides are inactive against Fusobacterium necrophorum , a common cause of pharyngitis in adolescents and adults. Delaying treatment 1 to 2 days until laboratory confirmation increases neither the duration of disease nor the incidence of complications.
Clindamycin mg 6. Erythromycin or clarithromycin mg 7. Because resistance of GABHS to macrolides has been detected, some authorities recommend in vitro confirmation of susceptibility if a macrolide is to be used and there is macrolide resistance in the community.
Clindamycin 6. Clindamycin has good activity against penicillinase-producing staphylococci or anaerobes coinfecting the tonsillar crypts and inactivating penicillin G. Sore throat, headache, and fever can be treated with analgesics or antipyretics. Aspirin should be avoided in children. Bed rest and isolation are unnecessary.
Close contacts who are symptomatic or have a history of poststreptococcal complications should be examined for streptococci. Cellulitis is often treated without doing a culture because isolating organisms can be difficult. Thus, regimens effective against both streptococci and staphylococci are used; for example, one of the following may be used:. Necrotizing fasciitis should be treated in an intensive care unit. Extensive sometimes repeated surgical debridement is required.
A recommended initial antibiotic regimen is a beta-lactam often a broad-spectrum drug until etiology is confirmed by culture plus clindamycin. Although streptococci remain susceptible to beta-lactam antibiotics, animal studies show that penicillin is not always effective against a large bacterial inoculum because the streptococci are not rapidly growing and may lack penicillin-binding proteins, which are the target of penicillin activity.
Cephalosporins or macrolides are usually effective, but susceptibility tests must guide therapy, especially in very ill, immunocompromised, or debilitated people and in people with foreign bodies at the infection site.
Surgical wound drainage and debridement as adjuncts to antimicrobial therapy may be lifesaving. Although vancomycin -resistant S. Most viridans streptococci are susceptible to penicillin G and other beta-lactams. Resistance is growing, and therapy for such strains should be dictated by results of in vitro susceptibility tests. Delayed nonsuppurative complications, including rheumatic fever and poststreptococcal glomerulonephritis, can occur.
Rapid antigen tests ie, for point-of-care use are very specific but not highly sensitive; confirm negative results using culture, at least in children. A penicillin or cephalosporin is preferred for pharyngitis; because macrolide resistance is increasing, susceptibility testing is recommended if that class of drugs is used. The following are some English-language resources that may be useful. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.
The Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics. Vancomycin resistant streptococci or other unknowns other than leuconostocs and pediococci, which are intrinsically vancomycin resistant. Top of Page. This solution is prepared in purified water and filter sterilized. A 10 ml aliquot is dispensed into sterile tubes.
This 0. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Streptococcus Laboratory. Section Navigation. Facebook Twitter LinkedIn Syndicate. Minus Related Pages. Section I. Place a vancomycin disk on the heaviest part of the inoculum, and put the plate into a candle extinction jar or a CO 2 incubator for 18 to 24 h at 35C. For most cultures submitted as group A streptococci, those that appear pure on the submitted culture, a 30 ml and a 5 ml Todd-Hewitt broth THB should be inoculated.
Do not incubate longer than 18 h. Some strains may take more than one day of incubation, no harm is done by incubating these broths longer than 24 to 72 h. The 30 ml THB is used for serogrouping and serotyping in some cases. If the culture is submitted as a nutritionally deficient Streptococcus NVS , inoculate an entire trypticase soy blood agar plate with the culture.
Perpendicular to this streak, carefully make a single streak with a Staphylococcus aureus culture. This test will determine if the unknown culture forms satellite colonies adjacent to the staphylococci, a characteristic of all NVS. Examples of unusual or unexpected results: The blood agar plates used in the manner described above are for checking for purity of cultures.
AccuProbe- Enterococcus Test Principle The AccuProbe- Enterococcus test is used to aid in the identification of atypical enterococci and to help differentiate between Enterococcus and Lactococcus strains. Reading and Interpretation Automated Limitations Use care with the amount of colonies used. Too many colonies will result in a false positive test.
Quality Control Quality controls, positive and negative reactions are determined each day the test is determined. AccuProbe- Pneumococcus Test Principle The AccuProbe- Pneumococcus test is used to aid in the identification of atypical pneumococci and to help differentiate between viridans Streptococcus strains. Acid Formation in Carbohydrate Broths Principle The ability of bacteria to form acid in some carbohydrate broths and not in others can be used in identification schemes.
If the bacteria acidify the carbohydrate, the pH will change and the indicator brom cresol purple will turn yellow. Most of the carbohydrate broths are commercially available Remel.
An asterisk indicates those that are made by CDC media lab. Pipet Procedure Inoculate carbohydrate broth tube with drops of inoculum. Fastidious organisms may be held up to 14d. Reading and Interpretation A positive reaction is recorded when the broth turns yellow. A negative reaction is when no color change occurs.
A definite color change that is not quite yellow may be interpreted as a weak positive reaction. Limitations Do not incubate in CO 2 as this may alter the pH. Quality Control Each lot and shipment of carbohydrate broth medium is tested for positive and negative reactions upon receipt in the laboratory. The strains and reactions for each broth are listed below. This hydrolysis results in an alkaline change in the media results in a color change in the media.
This test can be used for differentiated different bacteria. Inoculum A drop of Todd Hewitt broth culture grown overnight is the preferred inoculum. Alternatively a suspension in Todd Hewitt broth from growth on a plate or a tiny amount of growth from a plate may be used as the inoculum.
The medium is commercially available. Some fastidious organism may be held up to 14d. Reading and Interpretation A positive reaction is recorded with the broth turns a deep purple color indicating an alkaline reaction, NH 3 is released.
The development of a yellow color or no change in color of the broth indicates a negative reaction. Quality Control Each new lot and shipment of medium is tested for positive and negative reactions.
Top of Page Bacitracin Test Principle The bacitracin disk is sensitivity test used to differentiate the beta- hemolytic Streptococcus. Tap disk lightly to ensure that it adheres to the agar. Reading and Interpretation Any zone of inhibition is considered a positive test or sensitive test. Growth to the edge of the disk is interpreted as a negative test or resistant test. Limitations Quality Control Quality Control is performed on each shipment and lot of bacitracin disk.
Streptococcus pyogenes is the positive sensitive control and Enterococcus faecalis SS is the resistant or negative control. Results are recorded in the QC log book. Bile Esculin Test Principle A selective and differential medium used in the identification of catalase-negative bacteria.
The selective agent bile, inhibits most gram positive bacteria. The enterococci and Streptococcus bovis will grow. Esculin in the medium is hydrolyzed to esculetin and dextrose. The esculetin reacts with ferric chloride in the media to form a black-brown color. An inoculating loopful of culture may also be used.
Reagents and Materials Bile esculin slant Remel Procedure Inoculate tube with 1 drop of inoculum allowing drop to run down slant. Alternatively, the slant may be inoculated with a loopful of growth from a blood agar plate. Reading and Interpretation The bile esculin test is positive when a black color forms over one-half or more of the slant.
If no blackening occurs the test is negative. Limitations Do not incubate medium in a carbon dioxide atmosphere. The increase in C0 2 will cause the viridans streptococci to grow better and increase the likelihood of a positive BE reaction.
Streptococcus bovis and enterococci do not require C0 2 for good growth. Quality Control Positive and negative reactions are determined on each new lot and shipment of media.
Enterococcus faecalis strain SS is used for positive control reactions and Streptococcus sanguinis strain SS is used for negative control reactions.
A turbidity equal to that of 1. After a satisfactory density is achieved, divide the suspension into 2 tubes with approximately 0. Add 0. Mix by vigorous shaking. Reading and Interpretation Examine for clearing of the turbidity periodically.
A clearing of the turbidity in the bile tube but not in the saline control tube indicates a positive test, i. If the tube containing the cells and bile have not cleared the test is negative. On occasion some strains of pneumococci are only partially soluble in the bile salts, that is, a partial clearing occurs. These strains must have the proper zone of inhibition around the optochin test to be called pneumococci.
Partially soluble strains with zones of inhibition of less than 14 mm are not considered pneumococci. Limitations The turbidity must be sufficient to detect a difference in the saline control tube. Quality Control Each new lot of deoxycholate is tested for positive and negative reactions with S.
Results are recorded in QC log book. Top of Page Camp Test Principle Some bacteria produce CAMP factor a diffusible extracelluar protein that synergistically acts with the beta-lysin of Staphylococcus aureus and enhances the lysis of red blood cells.
Inoculum Growth from a blood agar plate or any solid media. Strain SS Strep. A single colony of the unknown strain beta hemolytic streptococci is picked up with an inoculating loop and used to make a single streak perpendicular but not touching the S. A mm space should remain between the streaks. Reading and Interpretation This enhanced activity is in the shape of an arrowhead at the juncture of the two streaks, with the widest portion of the arrowhead on the group B side.
Limitations Do not incubate in an anaerobic environment or under CO 2. Some S. Therefore it is necessary to test a known group B streptococcus for CAMP reaction as a positive control on each test plate.
Group B streptococcus strain SS should be used as a positive control on each test plate. Inoculum Cultures that are grown on a blood free media or a colony grown on a blood agar plate that is carefully transferred to a slide without carry-over of any of the erythrocytes.
Reagents and Materials Three percent hydrogen peroxide is obtained from a commercial drug store. Pipet Slides Procedure The catalase test is best performed by flooding the growth of the bacteria usually on an agar slant but blood free agar plates can be used in question with 1. The bacteria must be grown on blood free medium. Modifications of the catalase test may be performed by very carefully removing a colony of growth from a blood agar plate with a plastic needle or wooden applicator stick and transferring the colony to a glass slide.
Reading and Interpretation Any sign of bubbling is interpreted as a positive test. The absence of bubbling is interpreted as negative. Limitations False positive results will result if any red bloods cell are transferred. Weak positive results should be repeated on a blood free medium. The catalase test gives the majority of differentiations very efficiently, however, there will be occasions when the catalase test and colony morphology will be misleading.
Quality Control The catalase quality control is performed once per lot and shipment. For positive reaction use a blood-free culture of Staphylococcus aureus : i. Record in QC manual. This resistance is useful in differentiating the Lactococcus species. Reading and Interpretation Any zone of inhibition around the disk is considered sensitive.
Limitations Quality Control The quality control is tested with each lot and shipment. Lactococcus lactis is used for the negative control Sensitive and L. Top of Page Esculin Hydrolysis Principle A differential medium used in the identification of catalase-negative bacteria. An inoculating loopful of culture from a blood agar plate may also be used. Reagents and Materials Esculin slant Remel Procedure Inoculate slant tube with drops of inoculum allowing drop to run down slant.
Reading and Interpretation The esculin test is positive when a black color forms over one-half or more of the slant. The increase in C0 2 will cause the viridans streptococci to grow better and increase the likelihood of a positive reaction.
Enterococcus faecalis strain SS is used for positive control reactions and Streptococcus mitis strain SS is used for negative control reactions. Procedure The broth is inoculated with 2 or more colonies from a plate or with 1 to 2 drops of broth culture.
Reading and Interpretation Gas production is indicated by the gas formation between the broth and the petroleum jelly plug which pushes the wax plug toward the top of the tube. Small bubbles that may accumulate over the incubation period are not read as positive, only when the wax plug is separated from the broth is the test read positive. Most leuconostoc strains are positive at 24 h but some strains may take longer.
Results are recorded in the QC log. Top of Page Gram Stain Principle The gram stain is used to differentiate between gram-positive and gram-negative bacteria. Cellular morphology can also be determined. Gram-positive and gram-negative bacteria are both stained by crystal violet.
The addition of iodine forms a complex within the cell wall. Addition of a decolorizer removes the stain from gram-negative organisms due to their increased lipid content. These cells are stained pink with the counter stain safranin.
Inoculum The gram stain can be performed on the growth of any strain grown on any type of media. However, for this group of bacteria gram-positive cocci , it is best performed on the growth of bacteria in thioglycolate broth at 24h incubation. The staining procedure is modified when preparing the smear from thioglycolate broth. The smear can not be fixed to the slide with hear but must be fixed with methanol.
Allow the smear to air dry. No other catalase negative, gram positive cocci has these characteristics. Some strains grow in 6. Like the Leuconostoc s the pediococci are intrinsically resistant to vancomycin. They too were thought to be nonpathogenic for humans but there are several reports indicating that this is changing.
The Pediococcus strains appear very similar to the viridans streptococci on blood agar media and can be easily misidentified as viridans streptococci. All strains of pediococci tested have been resistant to vancomycin and all strains of viridans streptococci have been sensitive to vancomycin. This new genus of gram positive cocci has just recently been described. The origin of this genus is from a collection of viridans-like streptococci that most closely resembled Streptococcus uberis.
What makes Globicatella distinct from the viridans streptococci is that all the Globicatella strains were PYR positive, LAP negative and grow in broth containing 6.
This genus contains only one species. The tetragenococci differ from the pediococci by vancomycin resistance. The pediococci are vancomycin resistant and the tetragenococci are vancomycin sensitive. Other characteristics are similar. These bacteria grow very poorly on blood agar plates and will often take 48 h to grow. These bacteria may also resemble the viridans streptococci; occasionally the tetrads are not formed and only pairs and short chains are observed in the gram stain.
One species was previously identified as a streptococci, G. On blood agar plates some of the strains give an wide-zone alpha hemolytic reaction after extended incubation. Identifying these bacteria is difficult and an extended set of physiologic characteristics may have to be determined before final identification is possible.
These bacteria are characteristically negative in most tests listed in Table 1. Some strains are positive in both the PYR and LAP tests but other strains may fail to give a positive reaction in either. Salt tolerant Gemella -like genera include the Alloiococcus , Dolosigranulum , Facklamia , and Ignavigranum. The Aerococcus sp. All strains grow in broth containing 6. The strains grow well on blood agar media and form colonies somewhat smaller than the enterococci but larger than the viridans streptococci after overnight incubation.
Only one species of this genus is presently known, A. These bacteria have been isolated from the ear fluids of children with otitis. Like the Gemella e this bacterium is difficult to grow. Often 2 to 3 days are necessary for growth to develop on rabbit blood agar plates. They are differentiated from the Gemella e by the 6.
Alloiococci grow in 6. Two species of this genus are presently known. These bacteria have been isolated from wound infections. Like the Alloiococci and Gemella e these bacteria grow very slowly on blood agar media. The physiologic characteristics of helocococci are similar to the aerococci in that they are PYR positive, LAP negative, and grow in broth containing 6.
All isolates have been non-motile. Nutritionally variant streptococci NVS can be identified by demonstrating that the strain requires pyridoxal or grows on an agar plate only when a bacteria that satellites is present.
In addition to this requirement, NVS also give positive PYR tests, which helps to differentiate these strains from viridans streptococci. The most convenient way to begin to identify the streptococci is to determine the hemolysis of the bacteria on blood agar plates. As mentioned earlier the techniques for determining hemolysis is described in detail in; Isolation and Identification of streptococci, Part 1.
Collection, transport, and determination of hemolysis, Annex 1. Identification is confirmed by demonstrating the presence of the group A antigen on the streptococcal cells. All S. Some strains of S. Non-pyogenes strains grow more slowly and form smaller colonies than do S. When this occurs the strain should be tested for voges-proskauer VP reaction.
See Table 2 , for correct identification. Like group A streptococci, identification is confirmed by demonstrating that the streptococcal cells contain group B antigen. Since the group B antigen is not identified with any other streptococcal strain the terms Lancefield group B and S. The group C antigen is found with several different species and the S. Some have suggested that these strains be called S. Group F streptococci: S. Most of these strains have group F antigen, the next most frequently identified strain will have no group antigen, and only rarely will an anginosus strain have group A, C, or G antigen.
Technically some of these strains may be S. The majority of these strains will require additional carbon dioxide in the atmosphere for growth on blood agar plates. Often growth is not apparent until 48 h of incubation. Some of the strains are associated with infections of swine and they have specific group antigens. This bacterium may be submitted as a group A streptococci because it may react with the group A antibody in the latex slide agglutination assay.
It is also PYRase positive but is not sensitive to bacitracin. Whenever a latex agglutination group A positive bacterium is submitted that is not sensitive to bacitracin the group reaction should be confirmed using the Lancefield extraction procedure. Strains with group R, S, and T antigens are very similar to each other physiologically and the taxonomist have suggested that these strains should be called S. The strains are found commonly in swine and may be transmitted to man.
There are several reports of farmers and abattoir workers being infected with group R S. Identification of these bacteria is difficult without having knowledge that the infecting strain may be related to nonhuman sources. Demonstration of the group R, S, and T antigens with specific antisera is also difficult. It is suggested that if group R streptococci is the suspected agent in an infection the cells may have to be extracted with the formamide extraction technique in order to extract the group antigen.
The formamide extraction technique is described in Annex 2 Part II of Isolation and identification of streptococci. Table 2. Table 3. Differentiation of gram-positive cocci, atypical variants of group A streptococcci. Non-hemolytic variants of S. The non-beta hemolytic varieties of S.
The non-beta hemolytic varieties of these species are also included in the viridans streptococci identification tables. In all likelihood beta-hemolytic varieties of the S.
Table 4. Identification of the Streptococcus anginosus group. Data in table compiled from references 14, , In some instances where only the S. Pneumococcal surveillance cultures, pneumococcal epidemiologic investigation cultures, and non-sterile site isolates sputum are cultures that are examined only for pneumococci.
If the tests for optochin susceptibility and bile solubility are negative then the report can simply be no pneumococci present. Streptococcus pneumoniae : S. They can be identified and differentiated from the viridans streptococcal species by their susceptibility to optochin and bile solubility.
On occasion, some strains of viridans streptococci are susceptible to optochin or partially soluble in bile, but rarely will a culture of viridans streptococci be positive in both tests. Cultures suspected of being pneumococci isolated from systemic sources non-respiratory that are optochin susceptible and bile soluble but fail to serotype should be tested with the GenProbe pneumococcus probe.
All pneumococcal cultures should be serotyped by the Quellung reaction, with CDC produced typing antisera, see instructions below and Annex 3. Positive Quellung reactions are considered definitive identification of pneumococci. Table 5. Identification of nonbeta hemolytic gram-positive cocci in chains.
See footnote in Table 2 for positive and negative reactions. Note that the only way to differentiate S. Table 6. Shows key test in the differentiation of the virdidans streptococci. Most species can only be identified to viridans species group. The VP test aids in the identification and differentiation of the viridans streptococcal species and is a key reaction for the S.
The urea test is particularly useful in the identification of Streptococcus salivarius. Identification of major groups of viridans Streptococcus species.