Introduction

Primary peritonitis, an infection within the peritoneal cavity, is an uncommon condition in the paediatric population, typically caused by Gram-negative organisms, but very rarely caused by Gram-positive organisms, such as in this case of a 15-year-old female with Streptococcus pyogenes (S. pyogenes) primary peritonitis. This rare condition poses a significant diagnostic challenge for surgeons reviewing such patients.

Case: A 15-year-old, previously healthy Caucasian female patient is presented in this case.

She was brought to the emergency department by a parent with a one week history of gradually worsening, crampy, non-migratory abdominal pain that was worse in the right iliac fossa. This was associated with bouts of intermittent vomiting, watery diarrhoea, fevers, and loss of appetite.

There was no abnormal per-vaginal discharge or bleeding noted, with her last menstrual period started 2 weeks prior to presentation and had ended after 7 days with no changes to her regular cycle. She was sexually active with a single male partner with barrier protection (condoms) always utilised, neither partner had prior STI testing. The oral contraceptive pill (OCP) she normally took was ceased 2 weeks ago with no new contraceptive agents started and none prior to starting the OCP. She noted no urinary symptoms, no coryzal symptoms, and no rash. No recent travel or sick contacts were had. Her only past medical history was iron deficiency anaemia that was being treated with oral iron supplementation and no prior operations had been performed. She had no allergies. No significant family history was noted. The patient did not smoke, drink alcohol, or take recreational drugs.

On presentation, temperature was 39°C, heart rate was 120 beats per minute, blood pressure was 85/49, saturations 99% on room air, and respiratory rate was 16. On physical examination, she seen be a young female of slight build, agitated from pain, and subjectively pale. Her abdomen was distended, firm, and was globally tender with non-voluntary guarding.

In the emergency department, white cell count was 12.7x109/L with neutrophilia at 11.9x109/L. CRP was 238 mg/L. Microcytic anaemia was noted with a haemoglobin of 107 g/L with a MCV of 75fL. Lactate was 1.4. Urea/electrolytes/creatinine and liver function testing was unremarkable. Urine analysis was negative for leucocytes or nitrates and bHCG was negative for pregnancy. No imaging was done during her admission.

She received empirical broad-spectrum IV antibiotics with Augmentin 1000/200mg in the emergency department, as well as 2L intravenous crystalloid fluid resuscitation. She also received analgesia and antiemetics.

She was subsequently reviewed by the general surgical team and taken for a diagnostic laparoscopy on the same day by a consultant general surgeon. The operation revealed four quadrant purulent peritonitis with a normal appendix and abdominal organs were grossly normal. Gynaecological organs were grossly normal. Fluid samples were taken for MCS analysis and the abdomen was washed with 3L of normal saline. High vaginal swabs were also taken with a differential of PID.

IV antibiotic coverage was changed to IV Ceftriaxone, Metronidazole, and Azithromycin.

Patient continued to improve following 5 days total of IV antibiotic therapy and discharged home day 4 post operative. They were discussed with the local Infectious Diseases team and were subsequently stepped down to oral cefalexin, metronidazole, and doxycycline on discharge.

She was followed up via telehealth 5 days after discharge with the results of her peritoneal fluid MCS and high vaginal swabs having returned. The vaginal swabs were negative for gonorrhoea and chlamydia, and peritoneal fluid MCS was also negative for these. However, the peritoneal fluid did come back positive for Streptococcus pyogenes (sensitive to clindamycin, erythromycin). They were at this point rediscussed with the infectious diseases consultant and only oral cefalexin was continued for a further 5 days. They were reviewed by a general practitioner after antibiotics had ceased. At this time, she had improved clinically back to baseline and inflammatory markers were back within normal levels, hence antibiotic therapy was ceased. She has had no further issues (including recurrence) since and is not planned for any further follow-up at the time of writing.

Discussion

Primary peritonitis is infection within the peritoneal cavity not directly related to other intra-abdominal abnormalities, often monomicrobial, and is usually seen secondary to Gram-negative organisms. It accounts for less than 1-2% of paediatric abdominal emergencies, making it an increasingly rare phenomenon [1-3]. Streptococcus pyogenes, in the absence of risk factors including trauma, immunosuppression, or prior ascites, is not a common cause for primary peritonitis in children. However, it is an aggressive mimic to appendicitis and PID given similarities in symptomology. More commonly, the beta-haemolytic pathogen is associated with pharyngitis and various skin infections. While aetiology is uncertain, it has been speculated to spread via haematogenous, lymphatic and transmural means [4,5] S. pyogenes causing primary peritonitis is quite rare in the paediatric population. 46 of Group A Streptococcus primary peritonitis reported in English literature since 1980. 55-84% of cases previously identified in paediatric patients are in females [1,2,4-20]

Diagnosis of GAS primary peritonitis preoperatively as a cause for paediatric abdominal pain is rare. This is due to the infrequency of S. pyogenes as a causative organism in primary peritonitis, coupled with the abundance of other more prevalent differentials such as appendicitis. Difficulty in diagnosis and delay in appropriate treatment may lead to Streptococcal Toxic Shock Syndrome which carries with it a significant risk of severe complications and even death. Diagnosis often occurs post laparoscopic investigation and culturing of peritoneal fluid samples, such was the situation in this presented case. Broad-spectrum antibiotic coverage would be advocated for once diagnosis of primary peritonitis is made, until such time culture showing species and sensitivities return [2-4].

Conclusion

An unusual case of Streptococcus pyogenes primary peritonitis in a 15-year-old child is reported.

This phenomenon presents a diagnostic challenge for clinicians given its rarity and clinical mimics. Hence, an approach involving early use of broad-spectrum antibiotics is recommended in cases of clinical uncertainty until confirmation of diagnosis and return of causative organisms from cultures.

Funding

None

Conflict of interest

All authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest.

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