Reply to «Chlamydia trachomatis pneumonia: An underdiagnosed and potentially severe disease»

Dear Editor,

After carefully reading the letter to the editor from Dr Dorado et al.¹ entitled “Chlamydia trachomatis pneumonia: An underdiagnosed and potentially severe disease”, we would like to make the following comments.

First of all, we would like to thank Dr Dorado and her collaborators for the interest shown in our article and the great review they conducted on Chlamydia trachomatis pneumonitis in infants in our setting. Their experience is consistent with our data in that Chlamydia trachomatis is not an uncommon cause of afebrile pneumonia in infants and is probably underdiagnosed. Clinical suspicion and early diagnosis are of great importance, since, as they indicated, it can lead to serious complications and intensive care (IC) admission.

None of the patients in our series² required IC admission and the duration of hospitalisation was shorter (median of 6.5 days versus 9.5 days), perhaps because our patients had an older median age at diagnosis (58 days versus 48 days). However, we do agree on the typical clinical presentation and note that fever was uncommon in the series presented, as in our patients. Again, it is important to stress the importance of a history of conjunctivitis, as already mentioned by previous studies.³

We would like to point out that the main differential diagnoses for the presentation reported are pertussis-like syndrome and bronchiolitis. In this regard, the presence of eosinophilia in laboratory tests, found in a large part of the cases collected in both series and typical in C. trachomatis infection, as well as the slow course of the respiratory condition, are highly indicative data, and serve as microbiological evidence enabling a definitive diagnosis to be made.

Regarding diagnosis, the technique used is the same as that used at our centre (BD MAX CT/GC/TV, Becton Dickinson®). Therefore, although not approved by the FDA in nasopharyngeal samples, it is probably the technique of choice for diagnosing this disease.

Lastly, we would like to highlight the other piece that we believe is key to diagnosis: the maternal figure. We find that both the mother's age and the mother's foreign origin constitute risk factors for C. trachomatis respiratory infection in the first few months of life. We agree with the proposed screening for pregnant women, already done by Dr Piñeiro et al.⁴ and supported by Fabra et al.,⁵ but we would like to emphasise that the proposed risk age (under 25 years) for pregnant women excludes from screening 50% of the cases collected in their series and 75% of the cases in ours; therefore, it might be necessary to consider increasing the proposed risk age. We do agree that the mother's origin is a risk factor for this infection and that, therefore, this is the target population for screening.

In conclusion, we would like to reiterate that C. trachomatis infection is among the most common causes of afebrile pneumonia in infants; its clinical presentation is similar to that of other respiratory conditions (rhinorrhoea, cough and respiratory distress), and fever is uncommon. We would also like to highlight the main clues to diagnosis: a young mother, a mother of foreign origin, a history of conjunctivitis and a latent clinical picture, with eosinophilia as a laboratory finding. These enable the infection to be identified, the appropriate samples for the infection's diagnosis to be taken and early treatment to be started to prevent complications and IC admission.

Funding

No funding was received.

Conflicts of interest

The authors declare that they have no conflicts of interest.