Cutibacterium acnes subspecies/phylotypes can cause infections requiring antibiotic therapy. Phylotyping of 73 (55 acneic and 18 non-acneic) C. acnes strains was performed, and antibiotic susceptibility was tested by E tests, breakpoint susceptibility test, or disk diffusion method. The dominant phylotype in both acneic and non-acneic strains was IA1 (56.2%). Phylotype II was >3-fold more frequent in non-acneic than acneic isolates. Resistance in acneic strains was >41% for clindamycin, 36.4% for tetracycline and 15.9% for levofloxacin, and that in non-acneic strains was >38% for clindamycin, 22.2% for tetracycline and 5.6% for levofloxacin. No strain was piperacillin/tazobactam or vancomycin resistant. Amoxicillin resistance was found in both acneic (5.4%) and non-acneic strains (11.1%), and was rare (1.8%) in phylotype I but higher (23.5%) in other strains. Double resistance was found in 32.6% of acneic and 22.2% of the non-acneic strains, and 9.3% of acneic strains displayed multidrug resistance. In conclusion, IA1 phylotype was dominant in both acneic and non-acneic strains, and type II was more frequent in non-acneic isolates. The detection (at >6%) of amoxicillin resistance represents a rare yet important finding. The presence of double/multidrug resistance strongly implies the need of susceptibility-guided therapy of the associated infections.

Osteogenic sarcoma is a primary bone tumor characterized by malignant cells producing osteoid matrix. Ewing's sarcoma is a rare highly malignant bone tumor and second in frequency after osteosarcoma in children. Current treatment of both entities is multidisciplinary and consists of preoperative chemotherapy (sometimes in combination with radiation therapy), surgery to remove the tumor, and postoperative chemotherapy. Surgical treatment takes the main place for local control with excision of the tumor from the affected limb, rotational plasty and limb salvage operations with subsequent reconstructions.Limb salvage surgeries allow limb preservation and functionality, and with long-term follow-up the survival rate could reach 90% in the first 10 years.

Osteoid-osteoma and osteoblastoma are the two most common representatives of benign bone-forming tumors. Although both tumors are well known to the orthopedic community in Bulgaria, there are several rare localizations that would present difficulties in the diagnostic and therapeutic process. The purpose of our report is to present 4 pediatric cases with rare localization of osteoid-osteoma and osteoblastoma, diagnosed and treated in our clinic in the period between 2020-2022. The presented rare localizations of osteoid-osteoma and osteoblastoma may lead to a delay in making the correct diagnosis. Often, such patients are treated for long periods of time without much effect, which can lead to a deterioration in their quality of life.