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Streptococcus intermedius causing cellulitis of the penile shaft complicated with abscess formation and rupture after dry humping sex
  1. Fang Shen,
  2. Gowribahan Thevarajah and
  3. Janice Cheng
  1. Urology Department, Northern Hospital Epping, Melbourne, Victoria, Australia
  1. Correspondence to Dr Fang Shen; fshen{at}


Penile cellulitis with abscess formation then rupture is an extremely rare presentation. This is a case report of a penile shaft abscess caused by Streptococcus intermedius after ‘dry humping’ sexual activities. A 34-year-old healthy man was presented with painful penile swelling for 3 weeks after initial ‘dry humping’ and later penovaginal intercourse. He was admitted to the hospital for intravenous antibiotics treatment, but a penile abscess was developed and ruptured within 24 hours. Urgent penile exploration revealed localised abscess and S. intermedius was isolated. The wound healed by secondary intention. However, his admission was complicated by acute kidney injury, probably due to vancomycin. Therefore, longer inpatient supportive care was required before discharge. Given this severe complication of primary penile cutaneous infection by S. intermedius, our case would raise awareness of this normal flora in abscess development at the male genital region, and the importance for the patient seeking prompt medical advice and physicians administrating appropriate antibiotics.

  • infections
  • urinary and genital tract disorders
  • sexual transmitted infections (bacterial)
  • urological surgery

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Streptococcus intermedius is a β-haemolytic gram-positive coccus and belongs to one of the three members of the Streptococcus anginosus group.1 It is part of the normal microbiota found at various mucosal sites including respiratory, gastrointestinal and genitourinary tracts. It is increasingly recognised as an important pathogen that can cause invasive suppurative infections, especially in the head, neck and central nervous system. Penile abscess is uncommon and we reported a rare case of penile shaft skin cellulitis complicated with abscess formation and rupture in a healthy 34-year-old patient after heterosexual intercourse.2 S. intermedius was isolated from both the abscess and necrotic skin tissue. Therefore, our current case would add knowledge to the literature on this under-represented pathogen that can be acquired after sexual activities.

Case presentation

A 34-year-old man was presented to our emergency department (ED) with a 3-week history of intermittent penile swelling and pain following sexual activities. The swelling first occurred after non-penetrative sex, that is, ‘dry humping’ his female partner 3 weeks ago. Specifically, he rubbed his penis against a rough surface, that is, the jeans she wore, on his partner buttocks for sexual gratification as she was having menstrual periods at that time. He denied obvious penile skin abrasion or injury as a result of that. He did not seek medical advice at that time as symptoms resolved with oral analgesics after a few days. However, penile swelling and pain relapsed after a second penovaginal sexual intercourse with the same partner 1 week ago. Since then, pain and swelling progressively worsened and became unbearable to the point that he resorted to overdosing with oral analgesia (2 g paracetamol every 4 hours in the past 5 days). The patient also reported green/yellowish penile discharge beneath the foreskin (not from the urethral meatus) a few days before presentation to ED. He had no further sexual intercourse because of the pain and no penile erection was observable due to swelling. However, the patient had no difficulty in micturition, dysuria, haematuria, urinary frequency or other systemic symptoms. He denied other significant health issues and he is not on any regular medications. He works as a soldier from a regional military base.

On presentation to ED early in the morning, examinations showed he was afebrile with a soft non-tender abdomen, and no enlargement of the inguinal lymph nodes was palpable. There was also no tenderness or swelling in the testes. The only positive finding was a grossly red swollen penis. No obvious penile skin abrasions/lacerations, vesicles or pustules were seen. However, a 2–3 cm oedematous area was noted at the dorsal lateral aspect of the penile shaft (figure 1A). This area was corresponded to the point of maximum tenderness on examination. It was impossible to retract the prepuce due to the level of swelling. As a result, the urinary meatus and glans could not be examined, but no obvious discharge was noticed. A penile swab from the glans was taken for microscopy, culture and sensitivity (MCS) and sexually transmitted infections (STIs) screenings were sent while the patient was still in ED. He was admitted for intravenous (IV) antibiotics treatment. On reviewing the patient later on the ward, he complained of worsening of penile pain, had tachycardia and developed low-grade fever (38°C). Penile cellulitis was noticed to spread to the scrotum and skin necrosis was noticed at the previous oedematous area (figure 1B). Overnight, he reported spontaneous skin breakdown with purulent discharge. And the pain was relieved significantly because of that (figure 1C).

Figure 1

Penile cellulitis with abscess formation and spontaneous rupture requiring surgical debridement in a 34-year-old man. (A) The patient was presented to the emergency department (ED) with a swollen and erythematous penis, especially on the dorsal lateral aspect of the shaft. The maximum tenderness area (2–3 cm) appeared to be more oedematous. (B) 12 hours later, the erythematous area spread to the scrotum. A necrotic skin area became evident by that time. (C) The previous oedematous area ruptured spontaneously overnight with a significant amount of purulent discharge. (D) Emergent surgical debridement was delivered the next day, and the skin defect was about 4×1 cm before debridement. (E) Surgical exploration revealed localised shaft abscess without the involvement of underlying corpora. Necrotic and non-viable tissues were resected. Two thrombosed veins were noticed to travel proximally to distally at the centre of the defect. (F) The final skin defect after debridement was 4×5 cm in size. (G) 10 days postoperation, the wound healed well with healthy granulation tissues at the base. (H) 3 weeks later, the wound healed completely.

The next morning, a swab from the purulent drainage was taken and sent for MCS. Given his quick clinical deterioration, a decision was made on surgical debridement under general anaesthesia (figure 1D). Intraoperatively, thrombosis of penile cutaneous veins was noticed. The abscess was found to be localised and deeper structures like corpora were found to be intact. Plastic consult advised conservative debridement of the dorsal penile skin defect with an aim of secondary healing without grafting. Devitalised skin was removed and debrided tissue was also sent for MCS (figure 1E). The final skin defect was about 4×5 cm and was dressed with layered Mepitel silicone dressing (contact layer with silicone adhesion), betadine-soaked gauze and Combine dressing (highly absorbent thick layer of fleece enclosed in a non-woven fabric) (figure 1F). Postoperatively, the dressing was changed two times per day with UrgoTul (which contains hydrophobic substances and hydrophilic wound interface) covered by saline-soaked gauze and Combine dressing. Unfortunately, he developed acute renal injury (AKI), possibly due to antibiotic-related nephrotoxicity, which necessitated a longer hospital stay for monitoring of renal function recovery. Otherwise, the penile skin defects healed satisfactorily (figure 1G,H).


Laboratory investigations on ED presentation showed elevated white blood cell (WBC) count of 15.3×109/L (neutrophils 13.2×109/L) and C reactive protein (CRP) level of 51 mg/L. Other investigations, including urine chemistry, urine MCS, renal function test (urea, electrolytes and creatinine), liver function test, glycated haemoglobin and coagulation profile were all normal. Paracetamol level was below nomogram and thus no N-acetylcysteine (NAC) treatment was given. Urgent ultrasound (US) of testes and penis while in ED showed no focal lesion other than epididymal head cysts (figure 2A–D). The next morning, laboratory investigations were repeated after abscess rupture and showed rising CRP (95 mg/L) but normal WBC. Swab MCS from both the purulent discharge and the necrotic tissues showed heavy growth of S. intermedius. However, sensitivity was not performed per local laboratory protocol (table 1). Postoperative urine MCS was still negative, indicating urinary tract was unlikely to be the source of infection. STI screenings were all negative (serology for HIV, hepatitis, treponema pallidum, urine PCR for chlamydia trachomatis and Neisseria gonorrhoeae, and trichomonas vaginalis PCR).

Table 1

Microbiology investigation

Figure 2

Ultrasound scan of the scrotum and penis on presentation. Scrotum scan: A 2 mm oval shape hypogenic lesion was identified in the right testis (A), together with a right epididymal cyst (B). Penile scan: Transverse section (C) and longitudinal section (D) under right lateral access showed significant oedema at the right lateral aspect of the shaft, without focalised lesion.

Differential diagnosis

The top differential diagnosis on his ED presentation was penile shaft cellulitis, either from STI or urogenital tract microbiota. Other differentials include infectious dermatoses (eg, viral, mycotic, parasitic and bacterial infections), venereal penile oedema, lymphedema/lymphangitis of the penis, penile augmentation (eg, injection of liquid paraffin), deeper corpus cavernosum infection, penile trauma, priapism. In our patient, the unique ‘dry humping’ sexual history and inpatient course (signs of sepsis, quick abscess formation and spontaneous rupture) suggested an invasive suppurative pathogen of likely cutaneous/mucosal origin. Surgical debridement and microbiological investigations confirmed localised penile shaft infection by an uncommon streptococcus species.


The patient was initially treated with empirical intravenous flucloxacillin (2 g, every 6 hours) for 24 hours to cover common gram-positive organisms. Given quick clinical deterioration, surgical debridement under general anaesthesia was delivered the next day. Perioperatively, flucloxacillin was replaced by piperacillin/tazobactam (4.5 g, every 8 hours) and vancomycin (1.75 g, every 12 hours; patient weight 88 kg) to extend the coverage against gram-negative, gram-positive and anaerobic organisms. This antibiotic regimen was continued postoperatively for 24 hours and was switched to meropenem (500 mg, every 12 hours) because of the development of AKI. Oral amoxicillin/clavulanate (500 mg/125 mg, every 12 hours) was started after the isolation of S. intermedius and was continued for 10 days.

Outcome and follow-up

Patient was reviewed at outpatient clinic 3 weeks later. At that time, he had recovered completely from AKI and the penile skin defect also healed well. He reported normal erection function and was able to go back to work in the army.


The main lesson we learnt is the importance of not only prompt initiation of antibiotic therapy to abort the formation of a penile abscess but also prescription of the most appropriate antibiotic in correct dosage to avoid adverse drug related events. Penile infection involves either the superficial skin (glans, prepuce, shaft) or deeper erectile bodies (corpus cavernosum, spongiosum).3 Isolated penile cutaneous cellulitis is uncommon and is predominantly seen in sexually active young men. Venereal penile oedema, that is, penile swelling with low-grade cellulitis after vigorous sexual activity, can be an important differential. We presented a case of isolated penile shaft cellulitis with abscess formation and rupture in an otherwise healthy, immunocompetent young man after sexual activities. One likely aetiology would be the normal skin commensal has penetrated the skin barrier into subcutaneous tissues from ‘dry humping’ activities, that is, rubbing of genitals leading to subtle skin friction injury. Another less likely explanation would be pathogen was acquired through the later penovaginal sexual intercourse, that is, from the vaginal mucosa commensal. Nevertheless, the initial genital trauma still serves as an entry point for pathogens from either skin or vaginal commensal. Other mechanisms of trauma like a bite sustained during oral sex cannot be completely excluded.4

S. intermedius has been isolated as the responsible pathogen in the current case. S. intermedius is part of the commensal flora at various mucosal sites in humans, including the female genital tract.5 The significance of S. intermedius as an important human pathogen has been increasingly recognised because of its involvement in severe invasive suppurative infections at critical sites like the brain, liver and lung. S. intermedius has also been very occasionally isolated from corpus cavernosum abscesses.3 6 S. intermedius infection has a high tendency for abscess formation. It is more virulent than other members of the S. anginosus group in terms of longer hospital stays and higher mortality for patients. Our current case has added knowledge to the literature about this under-represented pathogen in terms that it can lead to severe complications in the urogenital area.

Our patient also developed AKI (stage 3) complicating his admission. Although his renal function recovered with supportive measures only (no dialysis required), this was still a serious adverse event. Vancomycin nephrotoxicity is likely to be the cause of AKI. However, S. intermedius sepsis could also be the initiation event given the patient had tachycardia and developed fever after admission. Septicemia alone might lead to the development of AKI and administration of vancomycin thus was a contributory/perpetuating factor. However, blood culture has not been taken at that time to support the latter hypothesis. Nevertheless, the second lesson we learnt is the importance of close monitoring and early detection of AKI in the setting of a likely septic process, especially when potentially nephrotoxic antibiotics were to be given. Appropriate antibiotic choice, given in correct dosage/duration and optimisation of fluid balance are all important aspects to prevent iatrogenic AKI.

US is appropriate for delineation of superficial soft tissue infection with its advantages like convenience and high sensitivity for soft tissue abscess.7 However, US did not show focal suppuration but generalised skin oedema only on his ED presentation. Therefore, the abscess was likely developed within 24 hours of admission and then ruptured overnight. S. intermedius virulent factors like hydrolytic enzymes are responsible for rapid tissue liquefaction and pus formation.1 According to local guidelines, benzylpenicillin or amoxycillin was recommended for S. intermedius infection. However, the antibiotic susceptibility test was not performed per local microbiology laboratory protocol despite susceptibility data have suggested that there was emerging penicillin resistance among S. intermedius isolates, further complicating therapeutic management of this pathogen.8 Early administration of effective antibiotics, such as metronidazole and ceftriaxone, to cover gram-positive, negative and anaerobic spectrum could have changed the course of the current case. This is especially important given the nephrotoxicity with a combination of vancomycin and piperacillin/tazobactam,9 which unfortunately happened in our patient. Therefore, further studies are needed to help with the rapid identification of S. intermedius and timely sensitivity testing. This might limit the antibiotic choice to a narrow spectrum single agent, and thus prevent adverse events relating to wide spectrum antibiotics use.

Patient’s perspective

I first had symptoms after dry humping my girlfriend as she was having periods at that time. I don’t remember I ever injured my penis and symptoms settled after taking Panadol. However, after the second sex, it becomes so painful and swollen. I know something must go wrong as I noticed discharge and the pain was unbearable. I felt the ultrasound scan made the pain even worse and it shocked me to see the pus coming out. I felt nauseated and lost appetite initially after surgery and now I felt much better. I am happy to go back to work and the wound healed quite well. There is no issue with sex function or passing urine. I hope I would have come to the hospital earlier to avoid surgery.

Learning points

  • Skin commensal Streptococcus intermedius is capable of penetrating the skin barrier into subcutaneous tissues from traumatic sexual activities like ‘dry humping’ and causing severe complications like abscess formation and rupture.

  • Patients need to seek prompt medical advice instead of shying away when developing swelling and pain of the penis as it can cause a delay in receiving effective antibiotics.

  • Ultrasound has limited sensitivity in identifying acute suppurative bacterial penile shaft infection, and clinical vigilance is required so that timely surgical intervention can be given if abscess formation is suspected.

  • Rapid identification and sensitivity analysis of pyogenic S. intermedius species will help with rationalising antibiotic choice and avoiding complications like vancomycin related acute kidney injury.

Ethics statements

Patient consent for publication



  • Contributors FS conceived and drafted the manuscript. TG performed the operation. JC reviewed the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.