Pneumonia gram-negative bacteria

The major precipitants of exacerbations of COPD are acute airways infections. The role of bacteria in precipitating exacerbations is controversial. Bacteria may have a primary role in the development of an exacerbation or represent a secondary superinfection of an initial viral process. The major bacterial organisms that have been associated with exacerbations are Haemophilus influenzae. Streptococcus pneumoniae, and Moraxella (Branhamella) catarrhalis. Mycoplasma pneumoniae and Chlamydia pneumoniae may play a part. In COPD patients with a FEVi < 35% predicted gram-negative bacteria, especially Enterobacteriaceae and Pseudomonas spp. play an important part in acute exacerbations. 

Moxifloxacin is an 8-methoxyquinolone with enhanced potency against important Gram-positive pathogens, notably Streptococcus pneumoniae (penicillin-resistant and penicillin-susceptible strains), and class activity against Gram-negative bacteria. Its activity is not affected by beta-lactamases. Moxifloxacin may therefore represent a promising alternative for treatment of respiratory tract infections (1). 

During multiple daily dosing peak serum concentrations of tobramycin over 5-7 pg/ml are associated with improved survival in patients with septicemia and pneumonia caused by Gram-negative bacteria (52,53). On the other hand, excessive peak concentrations (over 10-12 pg/ml) and trough concentrations (over 2 pg/ml) of tobramycin increase the risk of ototoxicity and nephrotoxicity (54). 

The macrolide antibiotics include erythromycin, clarithromycin, azithromycin, tylosin, tilmicosin and tiamulin. Clindamycin and lincomycin are related lincosamides. Susceptible bacteria include staphylococci, streptococci, Campylobacter jejunii, Clostridium spp., R. equi, Mycoplasma pneumoniae and Chlamydia spp. Drugs in this group are only effective against a few Gram-negative bacteria in cattle, namely some strains of Pasteurella and Haemophilus spp. Macrolides and lincosamides are associated with causing colitis in horses, so their use is usually restricted to p.o. erythromycin for the treatment of R. equi infections in foals. Subantimicrobial doses of erythromycin are administered i.v. to horses for gastrointestinal prokinetic action. 

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