**2. Symptoms**

Asymmetric movement of extremities, irritability and poor feeding may be often the early and unspecific findings of OM [9, 22]. Common symptoms include bone pain, swelling, red‐ ness, guarding and failure to move the affected body part (pseudoparalysis). Fever may or may not be present because of an immature immune system. It is important to ascertain joint involvement through the detection of pseudoparalysis and pain during passive movements and signs of local inflammation [22]. Dierig et al. [23] reported a newborn with combined OM and suppurative arthritis caused by *Streptococcus pyogenes* giving rise to right brachial plexus palsy. Acute haematogenous OM is usually defined acute if the signs or symptoms are pres‐ ent for less than 14 days, and subacute if signs or symptoms are present for more than 14 days. In neonates, acute forms predominate [1].

### **3. Causative microorganisms**

The causative agents of OM reflect those of neonatal sepsis, which vary from country to coun‐ try and in many cases remain unknown. The most common pathogen is *Staphylococcus aureus*, found in 70–90% of culture positive cases [24, 25]. Other pathogens include *Streptococcus* mainly group B (*Streptococcus agalactiae*) and Gram‐negative enteric bacteria (*Escherichia coli and Klebsiella pneumoni*a) *Pseudomonas aeruginosa* [26, 27]. Multi‐drug resistant *S. aureus*

(MRSA), community‐acquired strains of methicillin‐resistant *Staphylococcus aureus* (CA‐ MRSA) and *Kingella kingae* have emerged as being relevant in recent years and are responsible for serious infections [28]. *Candida albicans* OM needs to be considered in neonates, especially if preterms with specific risk factors. The presentation is more subtle and subacute, even in the absence of fever and elevated inflammatory markers. The progression is prolonged. OM from *Haemophilus influenzae* type b (Hib) has declined significantly; thanks to the introduction of the Hib vaccine.
