Diagnostic Clinical Microbiology: Endocarditis Case Studies Review

This report presents two case studies of endocarditis in children caused by Streptococcus pyogenes. The first case involves an unvaccinated Caucasian female presenting with fever, lethargy, and a rash, diagnosed with streptococcus pyogenes infection of the throat and showing signs of sepsis. Diagnostic approaches included blood cultures, ECG, and echocardiogram, leading to treatment with penicillin and other antimicrobials. The second case involves an 8-month-old South Asian female with sepsis and pneumonia, also testing positive for S. pyogenes. Diagnostic methods included chest X-ray, blood cultures, and echocardiograms. Treatment included penicillin and clindamycin. The report discusses the diagnostic approaches, treatments, and prognoses for each case, offering recommendations for improved patient care. The report highlights the importance of prompt diagnosis and treatment with appropriate antimicrobials, emphasizing the role of diagnostic microbiology in managing such infections. It also provides a review of the literature on the topic.

Running head: DIAGNOSTIC CLINICAL MICROBIOLOGY
DIAGNOSTIC CLINICAL MICROBIOLOGY
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Introduction
The prevalence of infective endocarditis (IE) is a rare condition that is diagnosed in
children. The Group A beta-hemolytic Streptococcus pyogenes however are responsible for
causing various types of infections with various severity of infections in childhood which
might invasive along with immune-mediated disease and toxin-mediated (Esposito et al.,
2016). This paper aims to present two cases of endocarditis caused by S. pyogenes and
additionally discuss the diagnostic approaches and treatment along with prognosis of the
disease caused in the respective cases.
Case 1:
Patient’s history
The case reveals the health condition of an unvaccinated Caucasian female who was
admitted to the rural Emergency Department. The patient had a history of fever along with a
three day of history of lethargy along with reduced oral uptake and showed erythematous
rash. Even after discharge from ED, the patient showed fever along with signs of sepsis. This
required her to be shifted to the ICU where she was being provided with fluid rehydration and
one dose of ceftriaxone was administered. The family history of the patient showed that out
of 6 of her siblings, at least 3 suffered from pharyngitis.
Different diagnostic approaches
The patient when diagnosed by the physician was mentioned to have a streptococcus
infection of the throat. During the examination the patient showed to have systolic murmur
along with purple nodules of the fingers and toes that are painfu, and erythema of the palms
and soles. The condition of the patient was hypotensive therefore she required infusions of
dopamine and epinephrine in order to maintain her blood pressure. The white blood count of

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the patient was seen to be 18.7×109 /L with 73% neutrophils. ECG was also conducted,
reports of which was normal. Additionally echocardiogram was done which showed a mass
that is mobile on the posterior mitral leaflet (0.7 cm × 0.5 cm) along with a small atrial septal
defect (ASD)/patent foramen ovale (PFO). Additionally computed tomography (CT) showed
that multiple bilateral asymmetric hypoattenuating foci. There was cardiac monitoring that
showed abnormalities and along with it there was a prompt repeat of ECG. This showed
accelerated junctional rhythm and atrioventricular (AV) dissociation Blood cultures were
drawn from the patient which showed positive results for Streptococcus pyogenes.
Treatments and prognosis
After the client tested positive for streptococcus pyogenes, treatment was initiated.
The antimicrobial of choice in the case study was penicillin. Other drugs that were used
include clindamycin, vancomycin and meropenem though the latter drugs were discontinued
after a short time. Penicillin is known to be a very effective antimicrobial if treatment is
initiated promptly. Penicillin acts by inhibiting the action of the enzyme Trans peptidase
which usually catalyze the final step in the cell wall biosynthesis and the cross-linking of
peptidoglycan (Singh & Ganjoo, 2017). The streptococcus pyogenes is a gram positive
bacteria and this means that it has a thick layer of the peptidoglycan that penicillin inhibits
cross-linking and this is why it was selected. The signs and symptoms improved after only a
short time of medication in the case study. In the case study, other drugs were also used and
they include meropenem and vancomycin though they were discontinued after a short time.
The rationale as to why they were used was to treat some strains of streptococcus that could
be resistant to penicillin (Weidman, Al-Hashami, & Morris, 2014). This is why they were
discontinued after the child or the patient responded well to penicillin. Prognosis can be
defined as the response to medication (Tseng et al., 2014). In this case study the prognosis for
the condition has been the portal of entry which is likely to be pharyngitis. Additionally there

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were chances of toxic showed from S.pyogenes that included including hypotension and a
generalized rash (Gupta et al., 2016).
Recommendations
Recommendations for this would suggest that before administration of clindamycin to
the patient, it condition of the patient needs to be assessed in a thorough way. This is because
clindamycin is a highly effective antibiotic therefore before its administration care should be
taken. Additionally before the administration of penicillin to the patient it needs to be made
sure that the patient does not have any allergy towards penicillin.
Case 2:
Patient’s history
This case presents the condition of a 8-month-old South Asian female who was
suspected with sepsis. The clinical history of the patient showed 1 week of fever along with
viral respiratory prodrome. Additionally there was a 2-day history of lethargy along with poor
oral intake.
Different diagnostic approaches
A chest x ray was conducted which showed right pleural effusion. Blood cultures had
been drawn from the patient which showed growth of Streptococcus pyogenes. As the patient
suffered from hemodynamic instability, there was a need to carry out transthoracic
echocardiogram in order to assess the cardiac function. It failed to show any signs of
endocarditis. Head CT was conducted that revealed bilateral asymmetric foci that was
extensive of white matter diffusion restriction. Repeat transthoracic echocardiogram showed
a tricuspid valve vegetation and a PFO (Jomaa et al., 2017).

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Treatments and prognosis
The initial treatment choice of the patient was antibiotics comprising of vancomycin,
cefotaxime, and oseltamivir, which helps to stop the growth of the bacteria acting especially
in the respiratory tract. After the results were positive for S.pyogenes, treatment using
penicillin was started as it helped to reduce the growth of this particular organism.
Additionally clindamycin was administered as the condition of the patient was too serious to
be only treated with penicillin. Clindamycin is in a class of medications called lincomycin
antibiotics. It works by slowing or stopping the growth of bacteria. The high doses of
penicillin helped to reduce the organism count in the blood. The prognosis for case 2
suggested that the initial cause of the infection is pneumonia. Additionally the second case
fits the definition of toxic shock (Singh & Ganjoo, 2017).
Recommendations
Recommendations for this would suggest that besides the different tests carried out, a
blood agar should also be used to diagnose for the streptococcus. The specimens for blood
culture and inoculation should also be collected at different times. This is because a positive
blood culture might be due to contamination. The inoculation on culture plates can therefore
be used as a confirmatory test for the Streptococcus pyogenes. This can be shown by the
zones of complete hemolysis.

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Conclusions
Endocarditis is one of the rarest infections in children. This condition is known to be
as a result of the gram positive bacteria known as Streptococcus pyogenes. This is a bacteria
that has thick layers of peptidoglycan and is a normal flora of the skin. During the assessment
of the respective patients, several diagnostic tests were carried out.
References
Esposito, S., Mayer, A., Krzysztofiak, A., Garazzino, S., Lipreri, R., Galli, L., … For the
Italian Pediatric Infective. (2016). Infective Endocarditis in Children in Italy from
2000 to 2015. Expert Review of Anti-infective Therapy, 14(3), 353-358.
doi:10.1586/14787210.2016.1136787
Gupta, S., Sakhuja, A., McGrath, E., & Asmar, B. (2016). Trends, microbiology, and
outcomes of infective endocarditis in children during 2000-2010 in the United States.
Congenital Heart Disease, 12(2), 196-201. doi:10.1111/chd.12425
Jomaa, W., Ben Ali, I., Abid, D., Hajri Ernez, S., Abid, L., Triki, F., … Maatouk, F. (2017).
Clinical features and prognosis of infective endocarditis in children: Insights from a
Tunisian multicentre registry. Archives of Cardiovascular Diseases, 110(12), 676-
681. doi:10.1016/j.acvd.2016.12.018
Mohapatra, S., Doulah, A., & Brown, E. (2017). Pneumococcal meningitis and endocarditis
in an infant: possible improved survival with factor V Leiden mutation. European
Journal of Pediatrics, 176(10), 1439-1442. doi:10.1007/s00431-017-2973-1

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Müller-Werdan, U., & Werdan, K. (2017). Infective endocarditis. Oxford Medicine Online.
doi:10.1093/med/9780198701590.003.0084
Singh, Y., & Ganjoo, N. (2017). Infective endocarditis in children. Paediatrics and Child
Health, 27(2), 68-74. doi:10.1016/j.paed.2016.09.003
Tseng, W., Chiu, S., Shao, P., Wang, J., Chen, C., Lin, M., … Wu, M. (2014). Changing
Spectrum of Infective Endocarditis in Children. The Pediatric Infectious Disease
Journal, 33(5), 467-471. doi:10.1097/inf.0000000000000145
Weidman, D. R., Al-Hashami, H., & Morris, S. K. (2014). Two cases and a review of
Streptococcus pyogenes endocarditis in children. BMC Pediatrics, 14(1).
doi:10.1186/1471-2431-14-227

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Appendix
Figure: Illustration of streptococcus pyogenes on blood Agar.