Streptococcus pneumoniae Septic Arthritis Complicating Hip Osteonecrosis in Adults: Case Report and Review of the Literature

A 42-year-old patient presented acutely with bacteremic pneumococcal pneumonia along with metastatic pneumococcal infection of the hip joint. Diagnostic evaluation revealed evidence of a pre-existing bilateral hip osteonecrosis. The osteonecrotic changes were attributed to chronic alcohol abuse and/or an old motor vehicle accident. Appropriate therapy was promptly instituted and the septic arthritis responded well, necessitating hip aspiration only once. A few months later, the patient had no permanent sequelae of the infection.

Key Points

* Streptococcus pneumoniae septic arthritis should be suspected in patients with arthritic symptoms and a concomitant pneumococcal infection.

* S pneumoniae septic arthritis of the hip is an uncommon infection, associated with certain predisposing factors. Osteonecrosis is an exceedingly rare predisposing factor.

* Prompt diagnosis and treatment are essential to prevent joint damage.

Streptococcus pneumoniae septic arthritis remains an uncommon infection in the adult population. Many physicians who treat patients with pneumococcal infections, mainly pneumonias, may not be familiar with this entity. This could result in significant morbidity related to the hip joint. We used the MEDLINE database to search the English language literature for similar cases. The occurrence of this syndrome as a complication of hip osteonecrosis has been rarely reported.

Case Report

A 42-year-old African-American man was brought to the emergency room with a 2-day history of steadily increasing right hip pain and a 3 to 4 day history of fevers with chills, cough productive of greenish sputum, generalized weakness and a recent accidental fall. Review of systems was otherwise unrevealing. He had sustained head and pelvic trauma during a motor vehicle accident (MVA) two years previously with residual left-sided spasticity and weakness. He was using a cane and, occasionally, a wheelchair. After the MVA, he had also developed seizures, necessitating antiepileptic therapy. There were no prior rheumatologic or other chronic diseases or infections. In addition, the patient gave a history of chronic alcohol abuse (40 ounces of beer per day for 25 years), as well as cocaine abuse. He denied other risk factors for human immunodeficiency virus (HIV) infection and reported a negative tuberculin skin test (PPD) 18 months before his presentation. He denied any sick contacts and was unemployed and living in a shelter house.

At admission, his temperature was 103.8°F and respiratory rate was 20 breaths/min. He was hemodynamically stable and in minimal respiratory distress with a pulse oximetry of 93% on room air. He was appropriately oriented with no signs of meningitis. Signs of consolidation were noted at the left base and a 2/6 midsystolic murmur was heard over the aortic area. He had a moderately sized ecchymosis on his anterior hip area and his right hip was tender to palpation with limited range of motion in all directions. Hip muscle group strength was 5/5 on the right and 4/5 on the left, while sensory examination was grossly normal. Left-sided spasticity was noted. All peripheral pulses were palpable.

Laboratory evaluation revealed leukocytosis with a left shift (WBC 12,400 cells/mm³, 82% neutrophils), an erythrocyte sedimentation rate (ESR) of 103 mm in the first hour, as well as normal liver and kidney function tests. Toxicology screen was positive for cocaine and opiates while phenytoin level was suboptimal. A chest film revealed a left lower lobe infiltrate, while computed tomography of the pelvis showed bilateral hip osteonecrosis, increased synovial fluid and early right femoral head osteomyelitis. Aspiration of the hip yielded 7 cm³ of purulent fluid with a fluid white cell count (WBC) of 42,000/mm³ (88% polymorphonuclear cells). The fluid Gram stain revealed no organisms but the fluid culture grew S pneumoniae (SP) at 24 hours with a penicillin minimum inhibitory concentration (MIC) of 0.06 μg/mL. The same organism grew from blood and sputum cultures.

The patient was originally given broad spectrum antibiotics which were subsequently changed to IV penicillin G. A transthoracic echocardiogram revealed no valve vegetation, while a repeat PPD and an HIV test were negative. He promptly defervesced while hip symptoms improved slowly. No more hip aspirations or open hip drainage were implemented. He was transferred to a rehabilitation center after 12 in-hospital days. He completed 4 weeks of IV penicillin and 2 weeks of oral penicillin therapy. Upon discharge 6 weeks later, he was ambulating with a cane, and 6 months later, he had completely recovered from his infection.

Discussion

S aureus and nongroup A β-hemolytic streptococci are the most frequently involved Gram positive bacteria in adult septic arthritides. S pneumoniae septic arthritis (SPSA) has always been an uncommon infection (3-10% of septic arthritides).^1-4 Nevertheless it does occur, even in the modern antibiotic era, as concluded from several case reports and a few reviews. The joint most frequently involved in SPSA is the knee, followed by the shoulder, the elbow and multiple joints.^2-5 Spine cases are also uncommon.⁶ Adults in their 5th or 6th decade seem to be more vulnerable to SPSA, with males predominating in some, but not all, series.^2,3,5-7 Several underlying articular and nonarticular illnesses and host factors have been reported to predispose to SPSA. Most of them will be mentioned during the more focused discussion on hip SPSA. Prior joint trauma is one of them.^2,6 Rarely, no underlying condition can be identified.

SPSA may involve one or more joints. Patients with rheumatoid arthritis (RA) are predisposed to polyarticular septic arthritis irrespective of etiology (up to 25%).¹ Uncommonly, prosthetic joints, usually knees and hips, are involved.⁷

SPSA is associated with pneumonia in 29 to 75% of cases, and less frequently with meningeal, endocardial or pleural space involvement (or combinations of those).^2-4,6 No extra-articular primary focus is found in 10 to 50% of patients.^3,4 Conversely, SPSA itself will seldom complicate pneumococcal pneumonia (0.3%).^3,5 Joint symptoms may appear before, during or after the primary infection has become evident,^2-4,6 and in over 50% of cases, temperature is elevated on presentation.^3,6 Symptoms and signs of arthritis are usually pronounced. A few patients present with a fulminant picture. The WBC count is often elevated with a left shift, as is the ESR (>90 mm/h in over 60% of cases).^3,6 Bacteremia occurs in 50 to 90% of SPSA cases.^3,6 The joint fluid is usually purulent, although it may look innocuous.^2,5 Positive fluid Gram stains and cultures are obtained in 70 to 85% and 60 to 85% of patients, respectively.^3,5 In most cases with negative cultures, prior antibiotics had been given. When serotyping is done, multiple serotypes are found, the majority of which are included in the 23-valent pneumococcal vaccine.^3,7

IV penicillin has been the drug of choice in SPSA, with 3^rd generation cephalosporins and vancomycin serving as alternatives.^2-4,6 Many cases of SPSA have been treated successfully with medical treatment alone, along with one or more closed-needle aspirations.³ Some centers use routine surgical lavage, either arthroscopic or open.⁴ Prosthetic joint SPSAs have also been adequately managed with antibiotics and surgical drainage alone.³ The prognosis in SPSA is usually favorable with appropriate antibiotics and joint drainage.^4-6 SPSA hip infections (SPSAH) are rare in adults.^4,5,7-17 Table 1 illustrates some primary features of the few SPSAH cases we found in the English medical literature. Some data were not available for all cases. Similar scattered case reports and a few case series can also be found in the non-English literature. The mean age of the 18 SPSAH cases reviewed (including ours) was 63 years, and the male to female ratio was 1:1. Several cases have involved relatively young individuals, like our patient.

Table 1

Underlying conditions included rheumatoid arthritis (RA) with or without corticosteroid use (in one case the patient also received anticytokine therapy),^8,11,17 alcohol abuse,^4,5,7 degenerative joint disease,^5,12,13 chronic obstructive pulmonary disease,^4,12,13 chronic heart disease,^4,13 end-stage renal disease with secondary hyperparathyroidism,¹⁴ malignancy,^4,9 splenectomy,^4,9,15 gastric surgery,^4,9 diabetes mellitus,¹² osteonecrosis⁷ and graft-versus-host disease.⁷

We were able to identify only two more adult SPSAH cases superimposed on hip osteonecrosis.⁷ Osteonecrosis usually occurs secondary to trauma but has also been associated with corticosteroid use, alcoholism, sickle cell anemia, infections, marrow infiltrating diseases, hypertriglyceridemia, HIV infection and autoimmune disorders.¹⁴ The femoral head is most commonly affected (up to 98% bilaterally).¹⁸ We attributed our patient's condition to prior trauma and chronic alcohol abuse.

Of note, pneumococcal arthritis seems to occur more frequently in children. In one series, S pneumoniae (SP) was the second most common isolate from children younger than 2 years with bacterial arthritis.¹⁹ In a retrospective review of cases of osteoarticular infections in children with sickle cell anemia, SP was the most common isolate from pure arthritis cases.²⁰ Ischemic bone necrosis in sickle cell anemia may predispose to SP infection, while a similar pathogenetic mechanism may have occurred in our patient.

In 6 of the 18 SPSAH cases (33%), there was polyarticular involvement. Half of the SPSAH cases involved prosthetic hips.^{7,10-13,16,17} There was concomitant pneumonia in 11/18 SPSAH cases (61%), meningitis in 3 and contiguous abscesses in 3 cases.

In our case, and in most SPSAH cases we found, there was a relatively short duration of symptoms, of 3 to 5 days. Interestingly, in 2 prosthetic SPSAH cases, the diagnosis was made with a delay of several months.^11,12 Temperature was always elevated on presentation for those cases where data was available and the majority presented with intense local symptoms and signs of inflammation. The WBC count was often, but not always, elevated (Table 2). The ESR was also usually elevated. Bacteremia occurred in most SPSAH cases (15/17, data missing for 1 patient). The joint fluid was usually purulent (7 of 9 cases with fluid description). The fluid WBC count was always increased with a left shift. Positive fluid Gram stains were infrequently noted (2 cases only, contrary to previous reports on SPSA) but joint fluid culture positivity was the rule. Few data on prior pneumococcal vaccinations were found. Our patient had not been vaccinated. Reports of infections by moderately or even highly resistant strains are emerging. Two SPSAH strains exhibited a penicillin MIC of 0.125 μg/mL and one of them was treated with vancomycin and rifampin.^7,9 Two other strains were penicillin resistant and intermediately resistant to ceftriaxone.^7,13 Our patient's strain was not typed and was highly susceptible to penicillin.

Table 2

Radiographic findings in the SPSAH cases reviewed included those of the underlying joint disease and, in addition, soft tissue swelling or effusion, joint destruction and adjacent osteomyelitis, prosthesis abnormalities and contiguous abscesses.

Most of the SPSAH patients were treated for 3 to 6 weeks of IV therapy, followed by various courses of oral therapy in some cases.

Among the 9 SPSAH cases involving natural hips, surgery (one or more procedures) was implemented in 4, and the remaining 5 were managed medically (although in one case, the patient died before the planned surgery). Among the prosthetic hip cases, surgical drainage was implemented in 7 of 9 cases and 5 of 9 prostheses were preserved. In our review, 14 of 18 patients survived and adequate mobility was preserved in 11 of the 14. Three patients died due to fulminant pneumococcal sepsis while one patient died because of miliary tuberculosis.

Conclusion

In summary, we describe an unusual case of S pneumoniae septic arthritis on top of hip osteonecrosis along with accompanying bacteremic pneumonia in an adult. Even though SPSA remains an unusual type of infection, it needs to be included in the differential diagnosis in cases of concomitant pulmonary and/or meningeal and joint infection.

Acknowledgments

Many thanks to Dr. John J. Ross for his prompt help with the literature search.