BACKGROUND: Despite the current trend toward less aggressive therapeutic approaches, acute haematogenous osteomyelitis (AHO) continues to be a challenge and is associated with significant morbidity worldwide. Our aim was to assess whether compliance with the current protocol was achieved in 80% of cases, to identify complications and the associated risk factors, and to analyse trends in the aetiology and management of AHO in the paediatric population.
METHODS: We conducted a longitudinal, observational, single-centre study in patients with AHO aged less than 18 years admitted to a paediatric hospital between 2008 and 2018 divided in 2 cohorts (before and after 2014). We analysed data concerning demographic and clinical characteristics and outcomes.
RESULTS: The study included 71 children with AHO, 56% male, with a median age of 3 years (interquartile range, 1-11). We found a 1.8-fold increase of cases in the last 5 years. The causative agent was identified in 37% of cases: MSSA (54%), MRSA (4%), S. pyogenes (19%), K. kingae (12%), S. pneumoniae (8%), and N. meningitidis (4%). Complications were identified in 45% of patients and sequelae in 3.6%. In recent years, there was an increase in myositis (30% vs 7%; P=.02), septic arthritis (68 vs 37.2%; p=0.012) and in the proportion of patients treated for less than 4 weeks (37 vs 3.5%; p=0.012), with a similar sequelae rates. The risk factors associated with complications were age 3 or more years, C-reactive protein levels of 20mg/L or higher, time elapsed between onset and admission of 5 or more days and positive culture, although the only factor that continued to be significantly associated in the multivariate analysis was positive culture. The presence of complications was a risk factor for sequelae at 6 months.
CONCLUSIONS: Our study confirms that AHO can be aggressive. The identification of risk factors for complications is essential for management.

BACKGROUND: Staphylococcus aureus and Staphylococcus pseudintermedius are highly important due to their capacity for producing diseases in humans and animals, respectively. The aim of the study was to investigate and characterize the coagulase positive Staphylococcus (CoPS) carriage in a Primary Healthcare Center population.
METHODS: Nasal swabs were obtained from 281 non-infectious patients. The CoPS isolates recovered were typed, and their resistance phenotype and genotype, as well as their virulence profiles, were analyzed.
RESULTS: CoPS isolates were recovered from 56/281 patients (19.9%). Fifty-five were S. aureus (19.6%), 54 were methicillin susceptible (MSSA) and one was methicillin resistant (MRSA). The remaining isolate was S. pseudintermedius (0.4%). A high diversity of spa-types (n=40) was detected, with 6 of them being new ones. The multi-locus-sequence-typing of 13 MSSA and one MRSA selected isolates was performed and the STs detected were: ST8, ST15, ST30, ST34, ST121, ST146, ST398, ST554, ST942, ST2499, and ST2500 (the last two STs being new). One MSSA isolate was typed as t1197-ST398-(Clonal complex)CC398. The MRSA isolate was typed as t002-ST146-CC5-SCCmec-IVc, and exhibited a multiresistance phenotype. The detected resistances were: penicillin (76%), macrolides (7%), tetracycline (7%), trimethoprim-sulfamethoxazole (7%), quinolones (7%), and lincosamides (5%). Five isolates contained lukF/lukS-PV genes, 17 tst gene, one eta gene, and two etb gene. The S. pseudintermedius isolate presented a new spa-type (t57) (belonging to a new ST180) and the genes lukS/F-I, siet, se-int, and expB.
CONCLUSIONS: A high genetic diversity of S. aureus was detected. Mention must be made of the identification of MSSA CC398 and S. pseudintermedius isolates in two patients, one of them with animal contact. The detection of the genes lukF/lukS-PV and tst should be noted.