Arthroscopic Treatment of Septic Arthritis of the Ankle Caused by Group B Streptococcus: A Case Report

Background

Group B streptococcus (GBS) is a well-known bacteria present in the vagina that can cause vaginitis, intra-amniotic infection, endomyometritis, and neonatal infections [1–5]. However, the role of GBS in non-pregnant women remains unknown. Although these bacteria often cause perinatal fever in adults, unrelated to parturition, this infection is generally seen in the elderly or in patients with chronic diseases, such as diabetes or malignancy. GBS has been reported to induce urinary tract infections, pneumonia, and endocarditis and occasionally arthritis, osteomyelitis, intra-abdominal abscesses, and pelvic abscesses [6,7]. The Papanicolaou (Pap) smear test, a well-known cervical cytology screening, had led to a decrease in the incidence of cervical cancer [8]. However, it is necessary to watch out for serious infection after undergoing a Papanicolaou test, considering that case reports have shown the development of fatal endocarditis in 2 cases [9,10] and septic arthritis of the shoulder in 1 case [11]. To the best of our knowledge, to date, there have been no reports of septic arthritis of the ankle after a Pap smear test. We present a case of arthritis of the ankle caused by GBS in an adult woman following a Pap smear test, which was managed by arthroscopic irrigation and debridement.

Case Report

A 60-year-old woman, who had previously completed the treatment of total laparoscopic hysterectomy with bilateral adnexectomy and postoperative chemotherapy for ovarian cancer (stage T1bN1bM0) 6 months before, underwent a routine Pap smear test. Four weeks later, she suddenly presented with high fever and abdominal pain, and gastroenteritis was diagnosed after these symptoms lasted for 2 days. The development of pain in the left ankle and swelling prompted radiographs to be taken at a nearby orthopedic clinic, but the radiographs showed no abnormal findings. Two days later, the patient consulted at our hospital owing to the persistence of symptoms of fever and pain in the left ankle with swelling. The cardiac examination was normal, without murmurs, and no other large or small joints were symptomatic. She had no history of any recent injury or medical procedure in her lower leg and had no comorbidities that could cause infections (eg, diabetes mellitus) or immune abnormalities. Her ankle movement was restricted due to progressive ankle pain, and her vital signs on examination were as follows: body temperature, 37.1°C; blood pressure, 96/57 mm Hg; heart rate, 71 beats per min; and oxygen saturation, 98% on room air. On physical examination, her left ankle was erythematous, swollen, and tender. Blood tests results revealed a white blood cell (WBC) count of 7700/mm3 (reference range, 3200–8600/mm3) with 77% neutrophils, a C-reactive protein (CRP) level of 28.9 mg/dL (range, <0.3 mg/dL), and an erythrocyte sedimentation rate of 98 mm/h (range, 3–15 mm/h). Other laboratory test results, such as a basic metabolic panel, were normal.

Radiographs revealed no abnormalities in her ankle (Figure 1), whereas ultrasound was able to detect joint effusion and surrounding synovitis. The ankle joint fluid, collected via aspiration, was turbid, white, and yellow in color. Gram-positive bacteria were isolated from both the ankle fluid and blood culture (Figure 2A, 2B), and GBS was confirmed 2 days later.

Septic arthritis of the ankle was diagnosed, and thus the patient underwent emergent arthroscopic irrigation and debridement under general anesthesia on the date of her first visit.

Synovial thickening and proliferation presented at the anterior, posterior (Figure 3A), and lateral (Figure 3B, 3C) sides of the intra-articular space, and synovectomy was performed. There was no cartilage injury. We closed the skin after inserting a drain and catheter for the continuous injection of antibiotics into the intra-articular space.

Intravenous antibiotic administration (sulbactam/ampicillin 6 g/day) was continued for 5 days after the emergent arthroscopic irrigation and debridement. In addition, continuous intraarticular infusion of amikacin (400 mg/day) was applied for 1 week. Four days after surgery, the CRP level decreased to 2.18 mg/dL, and the WBC count decreased to 5910/μL. Since the GBS culture showed higher sensitivity to ampicillin, we shifted the patient’s antibiotics to intravenous ampicillin (4 g/day). However, she had a purpuric drug eruption in her lower leg and abdomen 5 days later; thus, the antibiotics were changed to intravenous ceftriaxone (2 g/day). It took time for the skin symptoms to improve, but her ankle pain and swelling gradually improved. Although a genital infection in the pelvis was suspected because of the GBS infection, a computed tomography scan of the pelvis demonstrated no apparent abnormalities (Figure 4). Finally, the swollen ankle and serum CRP level improved, and the patient was discharged from the hospital with a 2-week course of oral antibiotics (garenoxacin mesilate hydrate) on day 20 after her hospitalization. Four months later, the patient had no ankle pain or restriction of ankle motion, without antibiotics.

Discussion

Septic arthritis of the ankle is a serious condition constituting a small portion (3–7%) of all forms of septic arthritis, which mainly affect the knee, hip, and shoulder [12]. Staphylococcus aureus is the most common organism found in septic ankle arthritis; however, the incidence of the GBS infection is on the rise as well. Invasive GBS infection in non-pregnant women has been reported to be increasing worldwide [13–15], and the incidence of septic arthritis caused by GBS has also increased [16–19]. Interestingly, in septic arthritis caused by GBS, oligoarthritis and polyarthritis (64–71%) are more common than monoarthritis (24–29%), as previously reported [17,18]. The knee is the most affected joint, whereas septic monoarthritis of the ankle is relatively rare [6,20]. The following risk factors for GBS infection have been identified: older age (>60 years), diabetes mellitus, presence of malignancy, HIV infection, and recent musculoskeletal surgery [14,16–18]. In the present case, our patient had a history of completed treatment of ovarian cancer 6 months prior; however, she had no risk factors at the onset of the GBS infection.

GBS commonly colonizes the female genital tract. Two previous reports have shown endocarditis caused by transient bacteremia 4 weeks after a routine Pap smear test was performed. In other cases of arthritis caused by GBS, 1 report showed that a 30-year-old woman had septic arthritis of the shoulder caused by GBS, and this was attributed to the Pap smear test performed 8 weeks before [11]. In our case, the septic arthritis of the ankle may have been caused by a bacterial invasion via transvaginal or enteral route due to the Pap smear test 4 weeks before, as previously reported. However, a vaginal bacterial culture was not performed at that time; therefore, it might be difficult to ascribe the noted GBS to transient bacteremia that supposedly arose from the Pap smear test.

Of course, there is also the possibility that the GBS could be transmitted through skin-to-skin contact, and that the fever and abdominal pain could suggest some kind of bacterial invasion, likely through the vaginal or gastrointestinal tract. For example, an echocardiogram may have provided further diagnostic assistance to find alternative source of infection, such as infective endocarditis.

The standard treatment of septic arthritis in a native joint consists of surgical arthroscopic irrigation and debridement, and these have good clinical outcomes in septic arthritis caused by GBS [20–23]. In our case, we performed arthroscopic irrigation and debridement at the patient’s first visit, which resulted in good clinical outcomes, including a restoration of the full range of motion of the affected ankle.

There may be some debate about the duration of antibiotic treatment. There are reports that 2 weeks of antibiotic therapy following initial surgical debridement for septic arthritis is not inferior to 4 weeks in terms of cure rates, adverse events, and sequelae [24]. We administered intravenous antibiotics for about 3 weeks; however, a shorter administration period might be better. Our continuous intra-articular infusion of amikacin was dependent on empirical knowledge, but not evidence based. We continued oral antibiotics after discharged from the hospital owing to concerns about the recurrence of infection; however, it might have been unnecessary. Surgery is the main approach, but it should be noted that appropriate use of antibiotics also assists the healing of infection.

Conclusions

The incidence of septic arthritis caused by GBS is on the rise worldwide. Although cervical cytology tests are essential in screening for cervical cancer, transient bacteremia can be induced. Thus, physicians must watch out for the development septic arthritis caused by GBS when patients present with fever or swollen joints after a recent Pap smear test. Emergent diagnosis and appropriate surgical intervention lead to good clinical outcomes.