Most common site of infection in neonates
Newborn
Group B streptococci
Gram-negative bacilli
Listeria monocytogenes
1-3 months
Streptococcus<unk> 
Chlamydia trachomatis
Haemophilus influenzae
Bordetella pertussis
Staphylococcus aureus
3 months-5 years
S.<unk> 
S. aureus
H. influenzae type b
Nontypeable H. influenzae
C. trachomatis
Mycoplasma<unk> 
5–18 years
M.<unk> 
S.<unk> 
C.<unk> 
H. influenzae type b
S. aureus
Group B streptococci
Gram-negative bacilli
Listeria monocytogenes
Streptococcus<unk> 
Chlamydia trachomatis
Haemophilus influenzae
Bordetella pertussis
Staphylococcus aureus
S.<unk> 
S. aureus
H. influenzae type b
Nontypeable H. influenzae
C. trachomatis
Mycoplasma<unk> 
M.<unk> 
S.<unk> 
C.<unk> 
H. influenzae type b
S. aureus
Pneumonia 
Upper respiratory infection 
Pleuritis
UTI
Atypical pneumonia
Sepsis
Lung abscess
Meningitis