**2. Infections in CSF drainage devices**

All surgical procedures carry a risk of infection, and the presence of a biomaterial significantly increases the risk [1, 2]. The insertion of silicone CSF drainage devices is no exception to this, and infection poses a real clinical problem. Hydrocephalus shunts are at risk of infection almost exclusively at the time of insertion or revision, and not thereafter. The main pathogen is coagulase negative staphylococci (CoNS) derived mainly from the patient's skin [3, 4], and entering the operative field during the procedure. Other bacteria are also involved, including *Cutibacterium acnes* [5, 6], also a skin commensal, and less often gram negative bacteria such as *Escherichia coli*. Infection rates have fallen in recent years, but still remain high in infants less than 6 months old [3, 7], and less so in adults [8]. The microbiology and pathology have been elucidated in previous publications [9, 10]. As EVD is by its nature an external device which also connects with other tissues and the central nervous system, it is perhaps not surprising that the infection rate is higher than in shunts. While many large institutions report rates of 8–10% [11], some recent studies have reported rates in excess of 20% [12]. Again the most common EVD pathogen is CoNS, but there is a higher proportion of gram negative bacteria, and particularly multi-drug-resistant strains including *Acinetobacter baumannii* [13]. The sources of EVD pathogens are the patient's skin and mucous membranes, staff managing the EVD, and the hospital environment. Ventricular access reservoirs are at risk at the time of insertion, but mainly during use, as with EVD. Infection rates are 5–8%, with ventriculitis/meningitis accounting for most cases but cellulitis around the reservoir occurs in 20% of cases. Most pathogens are derived from the skin, and include CoNS (56%) and *C acnes* (24%) [14, 15].

Infected shunts and EVDs should be removed a soon as possible and systemic antibiotics given, often for several weeks, but relapses are common [16]. In the case of infected reservoirs, successful treatment has been achieved with systemic and intrareservoir antibiotics without device removal [17, 18].
