الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Healthcare associated infections (HAIs) continue to remain an important cause of morbidity and mortality in the neonatal period. Newborns in neonatal intensive care units (NICU) are especially vulnerable to nosocomial infections due to a mixture of clinical, epidemiological and microbiological factors.
Premature sick neonates are inherently immunocompromised due immaturity of almost all components of their immune defences, and are subjected to multiple invasive procedures. NICUs provide an environment where there is high risk of colonization and cross infection by the prevalent resistant hospital pathogens, due to heavy antibiotic use, a situation further aggravated in many cases by understaffing, overcrowding and insufficiency of supplies, resulting in low level compliance with infection prevention and control measures. Blood stream infection (BSI) is among the most dangerous infections acquired in NICUs. (1)
The pathogens associated with neonatal sepsis are known to vary geographically. (2) In developing countries, Gram negative organisms are more common and are mainly represented by Klebsiella. (3) Local data from repeated studies in NICU of El Shatby Alexandria University Hospital, through the last fifteen years reported Klebsiella to be the main causative organism accounting for more than 52% of all neonatal BSIs. (4-6)
Klebsiella is an opportunistic pathogen that produces a number of virulence factors which contribute to its pathogenesis and enables it to interact with and survive in changing environments. (7) Klebsiella pneumoniae is the type species and the medically most important member of the genus Klebsiella. (7-8)
Klebsiellae develop prominent capsules which are the main determinants of their pathogenicity. (7) They protect the bacterium from phagocytosis by polymorphonuclear granulocytes, (9) inhibit opsonin independent phagocytosis “the lectinophagoctosis”, (7) prevent attack by phages, (10) prevent killing of the bacteria by bactericidal serum factors (11) and protects against desiccation. (10) Another important role of the capsule is its association with the later developmental stages of complex biofilm structures that display enhanced resistance to antibiotics. (10)
Klebsiellae secure their supply of iron which is an essential factor in bacterial growth by secreting high-affinity, iron chelators, siderophores, which are capable of competitively taking up iron bound to host proteins. (7)