Among the different serotypes of Streptococcus pneumoniae, serotype 3 has received global attention. We report the fatal case of a 76-year-old Japanese man who had an invasive pneumococcal disease associated with pneumonia caused by serotype 3 S. pneumoniae. The patient had a history of hypertension, laryngeal cancer, chronic obstructive pulmonary disease, and type 2 diabetes mellitus. Following a cerebral arteriovenous malformation hemorrhage, he underwent surgery to remove the hematoma and began rehabilitation. On day 66 of hospitalization, he suddenly developed a fever, and coarse crackles and wheezes were heard in his right lung. A diagnosis of hospital-acquired aspiration pneumonia was made, and initial treatment with piperacillin/tazobactam was started. Teicoplanin was added after S. pneumoniae was isolated from the blood culture, however, the patient died 5 days later. The S. pneumoniae detected in the sputum smear was serotype 3, showed mucoid colonies and susceptibility to penicillins, cephalosporins, carbapenems, and levofloxacin, but resistance to erythromycin. We experienced a fatal case of pneumonia caused by mucoid serotype 3 S. pneumoniae with a thick capsule. Serotype 3-associated pneumonia may develop a wider pulmonary infiltrative shadow, a prolonged therapeutic or hospitalization course, and a poor outcome. Careful observation and intervention are required, and the use of additional antibiotics or intravenous immunoglobulins should be considered in such cases. Pneumococcal immunization is also an important public health measure to minimize the development of severe infections caused by serotype 3 strains.

There is increasing evidence regarding the optimal therapeutic strategies for multidrug-resistant (MDR) bacteria that cause common infections and are resistant to existing antibiotics. Combination therapies, such as β-lactam combined with β-lactamase inhibitors or combination antibiotics, is a therapeutic strategy to overcome MDR bacteria. In recent years, the therapeutic options have expanded as certain combination drugs have been approved in more countries. However, only a handful of guidelines support these options, and the recommendations are based on low-quality evidence. This review describes the significance and efficacy of combination therapy as a therapeutic strategy against Gram-negative MDR pathogens based on previously reported meta-analyses.

We herein describe the case of a 63-year-old man who died from relapsed epidermal growth factor receptor gene (EGFR) exon 19 deletion lung adenocarcinoma treated with erlotinib. According to the autopsy results, he was confirmed to have small cell carcinoma without the EGFR T790M mutation in his pancreas and left kidney metastatic specimens, while the adenocarcinoma metastatic lesion in his right kidney had the EGFR T790M mutation; both retained the somatic EGFR exon 19 deletion. We herein report an autopsy case of resistance to an EGFR tyrosine kinase inhibitor via small cell carcinoma transformation and the EGFRT790M mutation in separate metastatic organs.