Q2 2019 Throat Culture

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Q2 2019 Throat Culture Specimen 6 - 9 year old Female, Fever, Organisms Extent 1 2 3 4 5 Total 922 - Neg for Grp A strep screen by culture 19 14 6 0 2 41 975 - Neg for strep Group A antigen 1 4 1 0 0 6 949 - No aerobic growth 1 1 1 0 0 3 976 - Pos for strep Group A antigen 0 1 0 0 0 1 815 - Lactobacillus sp.; NOS 0 0 0 0 1 1 919 - Neg for beta-hemolytic strep screen 1 0 0 0 0 1

TOTAL PARTICIPANTS 53 Flagging appears for failure to report (No additional codes). In addition to the required organism, participants in all extents may report 815, 919, 922, 949 and 975. This sample contained Lactobacillus spp.

This inoculated blood utilized for this patient’s throat culture was negative for pathogenic organisms, typically reported as “No pathogenic streptococci isolated”. While lactobacillus was present in this culture, this organism is a component of the upper respiratory tract (URT) microbiota (i.e., among other body sites). This organism and other microbiota from the URT (e.g., alpha-hemolytic streptococci, staphylococci, micrococci, corynebacteria (other than C. diphtheriae), yeast, etc.) isolated from a throat culture is typically added to the culture report as “Normal upper respiratory microbiota” or “Mixed flora”, for example.

Specimen 7 - 14 year old Male, Fever, severe sore throat Organisms Extent 1 2 3 4 5 Total 923 - Pos for Grp A strep screen by culture 20 14 7 0 2 43 976 - Pos for strep Group A antigen 1 5 1 0 0 7 825 - Neisseria sp.; NOS 0 0 0 0 1 1 887 - 0 0 0 0 1 1 921 - Pos for beta-hemolytic strep screen 1 0 0 0 0 1 922 - Neg for Grp A strep screen by culture 0 1 0 0 0 1

TOTAL PARTICIPANTS 54

Flagging appears for failure to report 881, 886, 887, 921, 923 or 976. In addition to the required organism, participants in all extents may report 825. This sample contained Streptococcus pyogenes, Group A and Neisseria spp.

Culture of this patient’s throat swab demonstrates significant growth of large (>0.5 mm) dome-shaped colonies surrounded by a wide zone of - on blood agar plate (BAP) after 24 (and 48) hours. The test was positive and the revealed gram-positive cocci in pairs/chains. Serological grouping, DNA probe or PYR testing can all confirm this organism as Streptococcus pyogenes. As in this patient, children ≥3 years with Group A typically have an abrupt onset with fever as well, which can be accompanied by nausea, abdominal pain and/or emesis. While other bacterial causes of pharyngitis include group C and G -hemolytic streptococci, Neisseria gonorrhoeae, Corynebacterium diphtheria, and Arcanobacterium haemolyticum, most cases have a viral etiology (e.g., enteroviruses, coronavirus, adenovirus). Saprophytic Neisseria spp. (not N. gonorrhoeae) was present in this culture and should have been apparent on BAP, as well. These organisms are normal human microbiota of the upper respiratory tract and are reported as such.

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Q2 2019 Throat Culture

Specimen 8 - 4 year old Male, Fever Organisms Extent 1 2 3 4 5 Total 923 - Pos for Grp A strep screen by culture 20 15 7 0 2 44 976 - Pos for strep Group A antigen 1 5 1 0 0 7 887 - Streptococcus pyogenes 0 0 0 0 1 1 883 - Streptococcus sp.; alpha-hemolytic 0 0 0 0 1 1 921 - Pos for beta-hemolytic strep screen 1 0 0 0 0 1

TOTAL PARTICIPANTS 54 Flagging appears for failure to report 881, 886, 887, 921, 923 or 976. In addition to the required organism, participants in all extents may report 883. This specimen contained Streptococcus pyogenes, Group A and alpha Strep.

Throat culture for this patient reveals abundant growth of Streptococcus pyogenes also referred to as Group A -hemolytic streptococcus (GABHS; based on the Lancefield classification for grouping streptococci according to their carbohydrate cell wall antigens) as well as -hemolytic streptococci. The symptoms of GABHS infections usually are atypical in young children. That is, instead of a well-defined episode of pharyngitis, these patients may have protracted symptoms of nasal congestion/discharge and low-grade fever. Alternatively, the clinical presentation may be a febrile illness alone, as in this case patient. As in the previous case, the presence of any -hemolytic streptococcus grown in a throat culture should be evaluated for possible clinical significance. Accordingly, any -hemolytic, catalaseneg, gram-positive cocci in pairs or chains can be confirmed as S. pyogenes by either: 1) positive PYR test; 2) positive result for GABHS antigen with immunological grouping test; or 3) positive DNA probe assay. Lastly, the presence of -hemolytic streptococci in this culture reflects the presence of commensal organisms in the oropharynx and should be reported as such (e.g., “S. pyogenes isolated along with usual upper respiratory microbiota”).

Specimen 9 - 33 year old Female, Sore throat Organisms Extent 1 2 3 4 5 Total 923 - Pos for Grp A strep screen by culture 19 15 6 0 2 42 976 - Pos for strep Group A antigen 1 5 1 0 0 7 921 - Pos for beta-hemolytic strep screen 1 0 1 0 0 2 825 - Neisseria sp.; NOS 0 0 0 0 1 1 887 - Streptococcus pyogenes 0 0 0 0 1 1 922 - Neg for Grp A strep screen by culture 1 0 0 0 0 1

TOTAL PARTICIPANTS 54 Flagging appears for failure to report 881, 886, 887, 921, 923 or 976. In addition to the required organism, participants in all extents may report 825. This specimen contained Streptococcus pyogenes, Group A and Neisseria spp.

As with Specimen #7, culture demonstrates abundant growth of Streptococcus pyogenes along with Neisseria spp. colonies from this patient’s throat culture. S. pyogenes or Group A -hemolytic streptococcus (GABHA) accounts for 30% of pharyngitis cases in children (ages 5 to 15), but only 10% of adult cases. So, while a rare case of acute pharyngitis for this demographic, it can and does occur. Given the emergence of commercial rapid diagnostic tests (RDTs; antigen- and nucleic acid-based) for GABHA and their comparable performance to that of culture, most guidelines are no longer recommending routine culture to back-up negative RDTs (especially, in this age category), but rather leave the decision to the physician to order when indicated (e.g., outbreak investigations, monitoring the spread of antimicrobial resistance, examination for pathogens other than GABHS).

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Q2 2019 Throat Culture

Specimen 10 - 18 year old Male, Fever Organisms Extent 1 2 3 4 5 Total 922 - Neg for Grp A strep screen by culture 20 14 5 0 2 41 975 - Neg for strep Group A antigen 1 5 0 0 0 6 919 - Neg for beta-hemolytic strep screen 1 1 0 0 0 2 949 - No aerobic growth 0 1 0 0 0 1 841 - Pseudomonas aeruginosa 0 0 0 0 1 1 976 - Pos for strep Group A antigen 0 0 1 0 0 1

TOTAL PARTICIPANTS 52

Flagging appears for failure to report 838, 841, 919, 922, 943, or 975. In addition to the required organism, participants in all extents may report (No additional codes). This sample contained Pseudomonas aeruginosa.

While this culture was positive for -hemolytic colonies, the organism displayed the typical smell (Concord grapes or corn tortilla) and colony morphology (metallic, rough, pigmented) of the gram-negative rod, Pseudomonas aeruginosa. Accordingly, gram-negative rods are not typically associated with acute pharyngitis and the patient’s fever likely due to some other (potentially infectious) disease process. Therefore, culture work-up would be unnecessary and throat culture can be reported as “No pathogenic streptococci isolated”.

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