Group B Streptococcus Persistently Colonizing the Adenosquamous Carcinoma of the Lung: A Blessing in Disguise?

Group B Streptococcus (GBS), also known as Streptococcus agalactiae, is a gram-negative, beta-hemolytic facultative anaerobe that causes neonatal pneumonia and sepsis. The neoplastic epithelial cells in adults, especially those of squamous origin, can show special adhesive properties toward GBS, which tends to reside within these tumors. There are some animal and human studies proving this association. Here, we present a 64-year-old female patient who had lung carcinoma of mixed adeno and squamous origin found to have persistent GBS every time the bronchoscopy was done for tumor ablation or cryotherapy. Subsequently, after starting her on chemo-radiotherapy, she also presented with multiple episodes of pneumonia caused by GBS and Pseudomonas aeruginosa. Moreover, many animal studies have shown the anti-tumor properties of GBS toxin that can prevent its metastasis and stop vascular growth surrounding the tumor. This property of GBS toxin can prove a blessing in disguise.