Pathogens of Hospital Acquired Pneumonia (HAP) Mild to moderate HAP or early severe HAP Streptococcus pneumoniae Haemophilus influenza MSSA Klebsiella pneumoniae Enterobacter e coli. Proteus. Serratia Severe HAp Pseudomonas Acinetobacter MRSA 2021/2/23 Dr HU Bijie
2021/2/23 Dr.HU Bijie 11 Pathogens of Hospital Acquired Pneumonia (HAP) • Mild to moderate HAP or early severe HAP – Streptococcus pneumoniae – Haemophilus influenza – MSSA – Klebsiella Pneumoniae – Enterobacter, E coli, Proteus, Serratia • Severe HAP – Pseudomonas – Acinetobacter – MRSA
Pneumococcal pneumonia 2021/2/23 Dr HU Bijie
2021/2/23 Dr.HU Bijie 12 Pneumococcal Pneumonia
Etiology: S pneumonia Gram-postive coccus most common identifiable cause of bacterial pneumonia and accounts for 2/3 of bacteremic CAP Pneumococcal pneumonia generally occurs sporadically but most frequently in winter It occurs most commonly in persons at age extremes 5 to 25% of healthy persons are carriers of pneumococci, with the highest rates noted in winter for children and parents of young children There are >80 serotypes(based on antigenically distinct capsular polysaccharides 2021/2/23 Dr HU Bijie 13
2021/2/23 Dr.HU Bijie 13 Etiology：S. pneumonia • Gram-postive coccus • most common identifiable cause of bacterial pneumonia and accounts for 2/3 of bacteremic CAP • Pneumococcal pneumonia generally occurs sporadically but most frequently in winter • It occurs most commonly in persons at age extremes. • 5 to 25% of healthy persons are carriers of pneumococci, with the highest rates noted in winter for children and parents of young children. • There are > 80 serotypes (based on antigenically distinct capsular polysaccharides)
Pathogenesis Host defenses impaired Inoculum sufficient to cause infection enters lower respiratory tract Virulent organism 2021/2/23 Dr HU Bijie
2021/2/23 Dr.HU Bijie 14 Pathogenesis • Host defenses impaired • Inoculum sufficient to cause infection enters lower respiratory tract • Virulent organism