A Report on Intraspinal Abscess Due to Community-Acquired Methicillin-Resistant Staphylococcus Aureus Infection
The incidence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections has been steadily increasing, with reports of such infections becoming more common each year. However, a case of intraspinal abscess caused by CA-MRSA infection has never been documented before. This report presents the first known case of intraspinal abscess due to CA-MRSA, detailing the clinical presentation, diagnostic process, treatment regimen, and outcomes.
Case Presentation
A 10-year-old Han Chinese girl developed a fever without an obvious cause. The peak temperature at the onset was approximately 38.5°C, and the fevers were irregular, accompanied by chills. Her temperature could be reduced to normal levels with antipyretic treatments. The patient had visited a footbath shop for manicure services due to paronychia 20 days prior to the onset of symptoms. A small amount of white viscous liquid had been drained from both great toes. About three days later, the patient developed paroxysmal arthralgia in both knees, low back pain, and a peak temperature of 40°C. She was admitted to a local hospital where blood tests revealed a white blood cell (WBC) count of 3.41×10^9/L, a C-reactive protein (CRP) concentration of 37.57 mg/L, and an erythrocyte sedimentation rate (ESR) of 26 mm/1h. Lumbosacral enhanced magnetic resonance imaging (MRI) showed an abnormal spinal extradural plate-like signal in the L4 and S2 vertebrae, which was considered inflammation, stenosis of the spinal canal, and a weak signal at L5 and S1 consistent with bone marrow edema. The patient was treated with penicillin for six days and vancomycin for three days, but the fevers and low back pain persisted.
Hospital Admission and Further Diagnosis
Eleven days after the onset of fevers, the patient was transferred to our hospital for further diagnosis and treatment. On admission, her weight was 50 kg, temperature was 38.2°C, heart rate was 85 beats per minute, respiration rate was 18 breaths per minute, and blood pressure was 103/63 mmHg. L4-S2 lumbar tenderness was pronounced, especially when leaning to the right side. Laboratory examinations showed a WBC count of 4.30×10^9/L, CRP concentration of 55.01 mg/L, procalcitonin concentration of 0.105 ng/mL, human serum amyloid A protein concentration of 156.6 mg/L, and ESR of 80 mm/1h. Two sets of blood cultures were negative. Mycobacterium tuberculosis IgG antibody and purified protein derivative were positive, while T-SPOT and Brucellosis tests were negative. Blood biochemical tests did not show any abnormalities, and Treponema pallidum and HIV antibodies were negative. Spinal MRI at our hospital showed L5 and S1 vertebral infections complicated with vertebral posterior abscess formation and secondary stenosis of the spinal canal at the same levels. The presumptive diagnosis was infectious lesions or tuberculosis.
Initial Treatment and Response
Therapy was initiated with cephalosporin 1 g every 8 hours combined with vancomycin 1 g every 12 hours from the first day at our hospital. The irregular fevers continued, but the peak temperature slightly decreased to 38.5°C, and the low back pain persisted. The patient was transferred to the spinal orthopedic department of our hospital on hospital day 12, and a repeat MRI was performed. On hospital day 26, posterior-lateral transforaminal microendoscopic lesion clearance and biopsy under local infiltration anesthesia and venous enhancement were performed. The intraoperative intrathecal abscess bacterial culture was positive for Staphylococcus aureus, and no acid-fast bacillus or cryptococcus was observed.
Definitive Diagnosis and Treatment Adjustment
After surgery, the patient was transferred back to the medical department. The drug sensitivity report showed that the minimum inhibitory concentration (MIC) of oxacillin, ampicillin, penicillin, and clindamycin were >2, >8, >0.25, and >2 mg/L, respectively. Based on the medical history, pus bacterial culture, and drug sensitivity report, the definitive diagnosis was CA-MRSA. According to the drug sensitivity results, the patient was treated with vancomycin 1 g every 12 hours combined with rifampicin 0.45 g every 24 hours, as the MIC of vancomycin and rifampicin were ≤1 and ≤0.5 mg/L, respectively. Cephalosporin was discontinued. Therapeutic monitoring of serum vancomycin was not performed during the treatment. Two days after surgery, her temperature normalized, and the low back pain markedly improved. Lumbar MRI 18 days after surgery showed abnormal signals on the vertebrae edge adjacent to L5 and S1, as well as on the intervertebral disc, but the range was slightly smaller.
Adverse Events and Final Treatment
Rifampicin was stopped 32 days after surgery due to leukopenia, skin rashes, and itching. The patient left our hospital after the symptoms completely resolved on day 32 post-surgery and continued to receive vancomycin treatment at the local hospital. Vancomycin was discontinued 50 days after surgery. MRI at that time showed that the abnormal signals on the vertebrae edge adjacent to L5 and S1 and the intervertebral discs had decreased. The patient received linezolid 10 mg/kg every 8 hours for two weeks from day 52 after surgery.
Discussion
Intraspinal infections often occur in patients with a history of lumbar spinal surgery, which might be caused by inappropriate preoperative preparation, surgical complications, blood infections, and improper wound management. Cases without a history of lumbar surgery or lumbar vertebrae fracture surgery developing symptoms of intraspinal infection are rare.
Due to the abuse of antibiotics, the number of drug-resistant strains has increased yearly. MRSA has gradually become a common pathogen. Reports of CA-MRSA have increased, with most involving skin, soft tissue, and other locations. Reports of facet joint arthritis due to CA-MRSA infection have been documented. However, intraspinal abscess formation caused by CA-MRSA infection has not been previously reported.
Antibiotic treatment should be adjusted according to drug sensitivity test results. Before drug sensitivity results are available, empirical treatment with vancomycin can be considered. When there is intraspinal abscess formation or nerve compression symptoms, incision and debridement should be performed to remove pus and inflammatory granulation tissue, which can speed up control of the infection and avoid further spread of inflammation.
The patient in this study underwent surgical debridement to remove the intraspinal abscess, and MRSA was cultured to provide a definitive diagnosis. Vancomycin, rifampicin, and oral linezolid were administered. The MRSA was sensitive to these three drugs, and the antibiotics could pass through the blood-brain barrier. The total treatment course was about 11 weeks, and the girl recovered.
Conclusion
This study reports a case of intraspinal abscess due to CA-MRSA. The incidence of CA-MRSA has been increasing. Although rare, CA-MRSA should be considered a possible pathogen in intraspinal infection without a history of lumbar spine surgery, which is helpful for timely diagnosis and treatment.
doi.org/10.1097/CM9.0000000000000074
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