Diabetic Patient with CA-MRSA Pneumonia and Plasma Cell Neoplasm: A Case Report of Severe Complications and Prognosis

Introduction

Studies have long reported associations between various tumors and different bacteria found in patients. These studies have typically focused on characterizing the bacteria within tumor tissues and their potential contribution to the development and staging of cancerous versus healthy tissue. However, the link between bacteria and cancer has been underestimated, and the role of infection in malignancy remains a subject of contention on whether it is causal or opportunistic [1,2].

Various bacterial species, including Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis, Enterococcus faecalis, and Salmonella sp., are associated with colorectal cancer. This association has been determined through sequencing studies in patients with colorectal cancer and functional research in cell culture and animal models [1,3].

Additionally, Helicobacter pylori has been found to contribute to gastric cancer and mucosa-associated lymphoid tissue lymphoma, due to chronic inflammation caused by the bacteria. This makes it a prime example of indirect cancer development [1].

Numerous clinical cases are reporting a significant link between the presence of S. aureus DNA and squamous cell carcinoma. Staphylococcus was found to be significantly more abundant in the group with oral squamous cell carcinomas than in healthy individuals. Additionally, extensive evidence strongly demonstrates a clear link between methicillin-resistant S. aureus (MRSA) and breast cancer [4].

S. aureus-induced community and hospital-acquired infections have the potential to cause significant harm to patient treatment and prognosis. MRSA’s ability to cause a variety of human diseases is likely due to a combination of the host’s virulence factors and the bacteria’s virulence factors [1].

S. aureus has started to become known for causing severe and dangerous infections, such as necrotizing pneumonia, necrotizing fasciitis, pyomyositis, osteomyelitis, and spondylodiscitis. Interestingly, there have been reports of subsequent hemato-logical malignancies diagnosed after severe infections, raising questions about their potential association [4–6].

The severity of the diseases caused by MRSA is likely due to a combination of virulence factors related to the bacteria and the host. Staphylococcal nuclease domain-containing protein 1 (SND1) is highly expressed in most cancers and has been shown to have a strong correlation with the prognosis of tumor patients [7].

Staphylococcus bacteria are significantly more prevalent in patients with malignancy, as confirmed by multiple clinical reports, and this contributes to a notable decrease in survival rates [1].

Case Report

In March 2022, a 48-year-old man with a known case of uncontrolled type 2 diabetes mellitus and non-compliance to oral hypoglycemic agents, previous surgical history including right fifth toe amputation, and recurrent incision and drainage of abscess presented to the Emergency Department with concerns of left-sided para-spinal back pain radiating to left chest for 5 days that started after he accidentally contacted a table at the site of the pain.

The patient’s vital signs were obtained and were as follows: temperature of 36.5°C, heart rate of 70 beats per min, respiratory rate of 26 counts per min, blood pressure of 135/874mmHg, and oxygen saturation of 91% on room air.

Chest examination revealed reduced air entry and bilateral crepitations. Upon inspecting the back, the patient had a crescent-shaped scar on the site of trauma with tenderness on palpation, as well as a scar on the mid-upper back, most likely from a previously drained abscess. A missing small toe on the right foot was also noted. The initial laboratory tests conducted on the patient included a complete blood count, renal function tests, liver function tests, a coagulation profile, an electrolytes bone panel, calcium, and measurement of the erythrocyte sedimentation rate (ESR). All the test results were within the reference range except for an elevated ESR, white blood cell (WBC) count, random blood sugar, and HBA1c. The patient’s WBC count was 14.69 cells/μL (reference range 4.5–11 cells/μL), ESR count was 100 mm/h (reference range 0–20 mm/h), random blood sugar level was 298 mg/dL (reference range 74–106 mg/dL), and HBA1c was 8.8% (reference range less than 5.6%). Previous cultures from a previous drained abscess showed pan-sensitive S. aureus was treated with oral antibiotics.

The chest radiograph demonstrated diffuse bilateral patchy airspace opacity with a bronchogram, in addition to cardiomegaly, with a lower-zone atelectatic band (Figure 1A).

Sputum and blood cultures were obtained, as well as samples for HIV and neuraminidase type 1 (H1N1) testing. Blood culture results for MRSA were positive by hospitalization day 3. H1N1 and HIV tests were negative. An echocardiogram was ordered to rule out infective endocarditis; this was also negative.

The patient received a diagnosis of CA-MRSA pneumonia, and because his D test reported sensitivity for macrolides and clindamycin, he was started on an intravenous course of clindamycin with a dosage of 900 mg 3 times per day.

The chest radiograph was repeated on the third day of the antibiotic course and revealed marked interval resolution of the bilateral large butterfly consolidation. However, the lower-zone atelectatic band was still apparent (Figure 1). The initial presentation of back pain was resolved 3 days after starting the antibiotics and analgesia administration.

After just 1 week of clindamycin administration, repeated blood cultures showed no growth. Even after 2 weeks, the cultures remained negative, but the repeated ESR indicated an increase in the rate from 100 mm/h on the day of admission to 120 mm/h, while the patient’s WBC count became normal, until the day of discharge.

On day 7 of admission, the patient developed severe back pain, which eventually resulted in a sudden inability to walk, necessitating consultation by a neurosurgeon.

Musculoskeletal examination revealed decreased muscle power (2/5) and a positive Babinski sign on both legs, predominately in the left leg; sensory examination for both legs was intact. On day 7, thoracolumbar magnetic resonance imaging of the spine was performed to obtain imaging for spinal and para-spinal etiologies, showing multilevel discopathy, particularly at T9–10, as well as ongoing nerve root conflict, with paravertebral collection (Figure 2).

On day 9, neurosurgeons performed posterior spine fixation at the site of spinal destruction. Histopathological analysis of the T9 vertebral body biopsy confirmed plasma cell neoplasm (Figure 3).

After 16 days of admission and against medical advice, the patient abruptly left the hospital. Three months later, the patient went to the Emergency Department with excruciating pain.

Further workup was done at his last presentation. A biopsy of the bone marrow in the left iliac crest identified greater than 10% plasma cells. Free light chain assay showed a normal kappa to lambda ratio, and no M band was noticed in serum protein electrophoresis.

After beginning a chemotherapy regimen with bortezomib and lenalidomide, the patient experienced low blood pressure and a fever, which required treatment with inotropes and antibiotics. Blood culture results identified MRSA, and vancomycin was recommended. Unfortunately, the patient only received inotropes and antibiotics for 1 day before dying.

Discussion

Infectious pathogens account for more than 20% of all malignancies worldwide. Bacteria and their role in cancer have received less attention than viruses. Bacteria can promote cancer growth by multiplying host cells’ signaling pathways, generating metabolites, and inducing inflammation [8].

S. aureus, a gram-positive coccus, is considered the most serious infectious disease in many hospitals and healthcare settings [5]. The ability of MRSA to cause a spectrum of human diseases may be linked to a combination of host and bacterial virulence factors, including cell surface-associated adhesins and secreted toxins. Staphylococcus causes disease by evading the immune system through various mechanisms, such as surface adhesion molecules, α-hemolysin, Panton-Valentine leucocidin, staphylococcal enterotoxins, staphylococcal protein A, toxic shock syndrome toxin-1, and other factors [3,4]. Staphylococcal nucleases, also known as Tudor-SN or p100, proteins containing the staphylococcal nuclease domain, are extracellular enzymes that act as genetic markers for S. aureus. SND1, a human homologue of staphylococcal nucleases, has been linked to various cancers, based on multiple studies [3,4].

S. aureus has been reported to enhance the risk of cancer formation, as documented in numerous case studies [4,7]. S. aureus, which primarily affects the skin and mucous membranes, has shown an association with the development of squamous skin cancer. This is explained by increased expression of human β-defensin-2 [4]. Furthermore, it has been linked to the development of various cancers, including breast cancer, bladder cancer, and colon cancer [4].

Furthermore, S. aureus leads to interleukin-6 secretion, which acts as a growth factor by activation and overexpression of monoclonal antibodies (IgA and IgG) and consequently leads to malignant plasma cells [3,6,9,10]. MRSA-caused pyomyositis was found to account for 7 out of 44 cases of multiple myeloma, with 1 case of plasma cell leukemia [6,7].

In our case history, the patient was initially able to walk without any neurological weakness, when diagnosed with severe pneumonia. After several weeks of antibiotic administration as an inpatient, he developed a lower limb neurological deficit that confirmed the presence of spondylotic lesions, suggesting plasma cell neoplasm through histopathological analysis of the destructed lesion from the vertebral body.

In a previous case report, a patient developed plasma cell neoplasm and clinically deteriorated 3 weeks after finishing a course of antibiotics; test results indicated S. aureus infection in the bloodstream [3]. In another case study, an elderly woman with hypertension received a diagnosis of multiple myeloma when she was admitted, and her condition was identified as pyomyositis caused by MRSA [6,7].

A limitation of our case study is that we could not conduct additional tests or investigations to determine the type of plasma cell dyscrasia, due to the death of the patient.

Conclusions

MRSA is known to cause serious and dangerous infections, including necrotizing pneumonia. With growing virulence, it has been linked to cancer cases and has been found to reduce survival rates. Moreover, a link between MRSA and plasma cell dyscrasia has been specifically identified in several reports. This necessitates the need for further studies to clarify this link, which could aid in the course and prognosis of these patients.