Atypical pathogens

The vast majority of pneumonia cases acquired in the community by otherwise healthy adults are due to S. pneumoniae (pneumococcus) (up to 75% of all acute bacterial pneumonias in the United States). Other common bacterial causes include M. pneumoniae, Legionella, and C. pneumoniae, which are referred to as atypical pathogens. Community-acquired... 

Due to its powerful specific activity against commonly isolated community-acquired respiratory tract pathogens [33,149-158], including penicillin-sensitive and -resistant Streptococcus pneumoniae, methicillin-sensitive Staphylococcus aureus, Haemophilus spp., Moraxella catarrhalis and atypical pathogens such as Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophila and Klebsiella pneumoniae and anaerobic bacteria [159-162], moxifloxacin was developed as a respiratory tract anti-infective [163-168]. 

Moxifloxacin has a broad spectrum of activity which includes Gram-positive cocci, atypical pathogens and anaerobic bacteria responsible, inter alia, for infections of the respiratory tract. Moreover, moxifloxacin is one of the most effective fluoroquinolones against pneumococci, including the penicillin- and macrolide-resistant strains. The development of resistance to moxifloxacin is slower than that of the other fluoroquinolones. 

Others. Leoofloxacin (t) 7h) has greater activity against Streptococcus pneumoniae than ciprofloxacin and is used for respiratory and urinary tract infection. Moxifloxacin (t) 12 h) has strong anti-Gram-positive activity, and may prove useful for respiratory tract infections including those caused by atypical pathogens and penicillin-resistant Streptococcus pneumoniae. 

Disease that is segmental or lobar in its distribution is usually caused by Streptococcus pneumoniae (pneumococcus). Haemophilus influenzae is a rare cause in this group, although it more often leads to exacerbations of chronic bronchitis and does cause pneumonia in patients infected with HIV. Benzyl-penicillin i.v. or amoxicillin p.o. are the treatments of choice if pneumococcal pneumonia is very likely alternatively, use erythromycin/clarithromycin in a penicillin-allergic patient. Seriously ill patients are best given benzylpenicillin (to cover the pneumococcus) plus ciprofloxacin (to cover Haemophilus and atypical pathogens). Where penicillin-resistant pneumococci are prevalent, i.v. cefotaxime is a reasonable best guess choice. 

Sparfloxacin is a fluoroquinolone with activity against the major respiratory pathogens and atypical pathogens that cause pneumonia. Photosensitivity, nausea, and diarrhea have been the most common adverse events reported in trials, and sparfloxacin is contraindicated in patients with QT interval prolongation (1). 

Erythromycin is indicated for the treatment of infections caused by erythromycin susceptible bacteria. The drug binds to the 50 S ribosomal subunit inhibiting bacterial RNA-dependent protein synthesis. Susceptible bacteria include most Gram-positive bacteria and the atypical pathogens. 

Eile TM, Tan JS, Plouffe JE. The role of atypical pathogens Mycoplasma pneumoniae, Chlamydia pneumoniae and Legionella pneumophila in respiratory infection. Infect Dis Clin North Am 1998 12 569-592. 

If she has a community-acquired pneumonia, coverage must be provided for pneumococci and atypical pathogens. In such a case, the most appropriate drug treatment in this patient is... 

Currently, biological samples are taken from the patient and delivered to the laboratory for analysis. After identification through culture or diagnostic assay, the results are sent back to the treating facility for use in medical management of the patient. Most communicable disease surveillance systems rely on telephonic or weekly written reports for subsequent transmission of this information to local or state health officials. Even if a suspect atypical pathogen is identified and interested health care staff make special efforts to report, the time lag before the health department knows of the culture may exceed 3 days. 

Infective endocarditis (IE) is a serious infection affecting the lining and valves of the heart. While this disease is mostly associated with infection of the heart valves, the septal defects may become involved as well. Infections also occur in patients with prosthetic or mechanical devices, such as mechanical heart valves or who are intravenous drug users (IVDUs). Bacteria is the primary cause of IE however, fungi and atypical organisms also can be responsible pathogens. 

LG Chem in Daejeon, Korea, performed the multistep synthesis of Gemifloxacin (FACTIVE), a quinolone antibiotic drug with enhanced activity against G(+) bacteria [30]. This drug has high activity against G(—) bacteria, atypical strains and major respiratory pathogens. 

So-called atypical bacteria such as Chlamydia pneumoniae and Mycoplasma pneumoniae are the next most important group of community-acquired pneumonia pathogens, accounting for around one case in every eight in hospitalised patients. Atypical bacteria are not sensitive to beta-lactam antibiotics such as penicillins and cephalosporins and the treatment of choice is a macrolide such as erythromycin. 

Mycobacterium scrofulaceum may cause granulomatous hepatitis. Clinical findings include a clear increase in alkaline phosphatase as well as fever and general malaise. Diagnosis is confirmed by positive culture of the pathogen in liver biopsy specimens. (61) Other atypical mycobacteria may also cause liver damage, possibly in the form of granulomatous hepatitis, especially in AIDS (20-50% of cases). (58) (s. fig. 24.7)... 

Alatrofloxacin is a fluoronaphthyridone that is hydrolysed to the active moiety, trovafloxacin, after intravenous administration. This fourth-generation broad-spectrum fluoroquinolone has activity against Gram-positive, Gram-negative, anerobic, and atypical respiratory pathogens. Because it has significant hepato-toxicity, the list of appropriate indications for trovafloxacin has been restricted. 

Levofloxacin, the levorotatory (5)-enantiomer of the racemate ofloxacin, is an oral and parenteral fluoroquinolone that has bactericidal activity against a wide spectrum of Gram-negative and Gram-positive bacilli (including Streptococcus pneumoniae), as well as atypical respiratory pathogens. 

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