Patients with culture-documented Chlamydia pneumoniae respiratory infection, including community-acquired pneumonia, generally respond very well to antibiotic treatment with faster resolution of symptoms.[11]Gray GC, Witucki PJ, Gould MT, et al. Randomized, placebo-controlled clinical trial of oral azithromycin prophylaxis against respiratory infections in a high-risk young adult population. Clin Infect Dis. 2001 Oct 1;33(7):983-9.
http://cid.oxfordjournals.org/content/33/7/983.long
http://www.ncbi.nlm.nih.gov/pubmed/11528569?tool=bestpractice.com
[12]Kohlhoff SA, Hammerschlag MR. Treatment of chlamydial infections: 2014 update. Expert Opin Pharmacother. 2015 Feb;16(2):205-12.
http://www.ncbi.nlm.nih.gov/pubmed/25579069?tool=bestpractice.com
Approximately 10% of patients may require a second course of treatment. Chlamydia pneumoniae may persist in the respiratory tract after acute illness for periods of 6 months or longer if not treated.[22]Hammerschlag MR, Chirgwin K, Roblin PM, et al. Persistent infection with Chlamydia pneumoniae following acute respiratory illness. Clin Infect Dis. 1992 Jan;14(1):178-82.
http://www.ncbi.nlm.nih.gov/pubmed/1571425?tool=bestpractice.com
[23]Emre U, Roblin PM, Gelling M, et al. The association of Chlamydia pneumoniae infection and reactive airway disease in children. Arch Pediatr Adolesc Med. 1994 Jul;148(7):727-32.
http://www.ncbi.nlm.nih.gov/pubmed/8019629?tool=bestpractice.com
However, most patients improve clinically despite persistence of the organism.[13]Hammerschlag MR, Roblin PM. Microbiologic efficacy of levofloxacin for the treatment of community-acquired pneumonia due to Chlamydia pneumoniae. Antimicrob Agents Chemother. 2000 May;44(5):1409.
http://aac.asm.org/cgi/content/full/44/5/1409
http://www.ncbi.nlm.nih.gov/pubmed/10819727?tool=bestpractice.com
[14]Hammerschlag MR, Roblin PM. Microbiologic efficacy of moxifloxacin for the treatment of community-acquired pneumonia due to Chlamydia pneumoniae. Int J Antimicrob Agents. 2000 Jul;15(2):149-52.
http://www.ncbi.nlm.nih.gov/pubmed/10854812?tool=bestpractice.com
[19]Block S, Hedrick J, Hammerschlag MR, et al. Mycoplasma pneumoniae and Chlamydia pneumoniae in community acquired pneumonia in children: comparative safety and efficacy of clarithromycin and erythromycin suspensions. Pediatr Infect Dis J. 1995 Jun;14(6):471-7.
http://www.ncbi.nlm.nih.gov/pubmed/7667050?tool=bestpractice.com
[20]Harris J-A, Kolokathis A, Campbell M, et al. Safety and efficacy of azithromycin in the treatment of community acquired pneumonia in children. Pediatr Infect Dis J. 1998 Oct;17(10):865-71.
http://www.ncbi.nlm.nih.gov/pubmed/9802626?tool=bestpractice.com
[21]Roblin PM, Hammerschlag MR. Microbiologic efficacy of azithro-mycin and susceptibility to azithromycin of isolates of Chlamydia pneumoniae from adults and children with community acquired pneumonia. Antimicrob Agents Chemother. 1998 Jan;42(1):194-6.
http://aac.asm.org/cgi/content/full/42/1/194
http://www.ncbi.nlm.nih.gov/pubmed/9449287?tool=bestpractice.com
True antibiotic resistance in C pneumoniae in patients after treatment has not been demonstrated. In vitro susceptibility testing of isolates obtained from patients with persistent infection have not demonstrated any change from isolates obtained at baseline.[13]Hammerschlag MR, Roblin PM. Microbiologic efficacy of levofloxacin for the treatment of community-acquired pneumonia due to Chlamydia pneumoniae. Antimicrob Agents Chemother. 2000 May;44(5):1409.
http://aac.asm.org/cgi/content/full/44/5/1409
http://www.ncbi.nlm.nih.gov/pubmed/10819727?tool=bestpractice.com
[14]Hammerschlag MR, Roblin PM. Microbiologic efficacy of moxifloxacin for the treatment of community-acquired pneumonia due to Chlamydia pneumoniae. Int J Antimicrob Agents. 2000 Jul;15(2):149-52.
http://www.ncbi.nlm.nih.gov/pubmed/10854812?tool=bestpractice.com
[21]Roblin PM, Hammerschlag MR. Microbiologic efficacy of azithro-mycin and susceptibility to azithromycin of isolates of Chlamydia pneumoniae from adults and children with community acquired pneumonia. Antimicrob Agents Chemother. 1998 Jan;42(1):194-6.
http://aac.asm.org/cgi/content/full/42/1/194
http://www.ncbi.nlm.nih.gov/pubmed/9449287?tool=bestpractice.com
[24]Riska PF, Kutlin A, Ajiboye P, et al. Genetic and culture-based approaches for detecting macrolide resistance in Chlamydia pneumoniae. Antimicrob Agents Chemother. 2004 Sep;48(9):3586-90.
http://aac.asm.org/cgi/content/full/48/9/3586
http://www.ncbi.nlm.nih.gov/pubmed/15328134?tool=bestpractice.com
As culture is not performed routinely in the clinical setting, it is not possible to determine if persistence is secondary to resistance, or even if the organism is still present. However, C pneumoniae does not appear to easily develop resistance in vitro.[24]Riska PF, Kutlin A, Ajiboye P, et al. Genetic and culture-based approaches for detecting macrolide resistance in Chlamydia pneumoniae. Antimicrob Agents Chemother. 2004 Sep;48(9):3586-90.
http://aac.asm.org/cgi/content/full/48/9/3586
http://www.ncbi.nlm.nih.gov/pubmed/15328134?tool=bestpractice.com