ORIGINAL STUDIES Mycoplasma pneumoniae and Respiratory Virus Infections in Children With Persistent Cough in England A Retrospective Analysis Kay Wang, MRCGP,* Victoria Chalker, PhD,† Alison Bermingham, PhD,‡ Timothy Harrison, PhD,† David Mant, FRCP, FRCGP, FMedSci,* and Anthony Harnden, MSc, FRCGP, FRCPCH* Background: Persistent cough following an acute respiratory tract infec- tion is common in children, but clinicians may find it difficult to give accurate prognostic information on likely duration of cough without a microbiologic diagnosis. This study estimates the prevalence of Myco- plasma pneumoniae (Mp) and assesses the prognostic value of detecting Mp and respiratory viruses in children with persistent cough. Methods: We retrospectively analyzed blood samples, nasopharyngeal aspirates (NPAs), and cough duration data from 179 children with persis- tent cough lasting 14 days or longer. Of these children, 37% had serolog- ically confirmed Bordetella pertussis (pertussis). We detected Mp by polymerase chain reaction of NPAs and IgM serology, and respiratory viruses (human rhinoviruses, influenza viruses, respiratory syncytial vi- ruses, and human metapneumovirus) by polymerase chain reaction of NPAs. We used Kaplan–Meier analyses to calculate median cough dura- tions with 95% confidence intervals (CIs). Results: We detected Mp in 22 of 170 children with sufficient blood and/or NPAs (12.9%, 95% CI: 8.7–18.8). Cough duration in children with positive Mp serology (median: 39 days, 95% CI: 24 –54) was significantly shorter than in children with positive pertussis serology (median: 118 days, 95% CI: 82–154, P  0.001). The presence of respiratory viruses did not significantly lengthen cough duration in children with pertussis (median: 154 days, 95% CI: 74 –234, P  0.810). Only 3 children had both Mp and respiratory virus infections. Conclusions: Mp is an important infection in children with persistent cough and is associated with a significantly shorter duration of cough than pertussis. However, detecting respiratory viruses does not add prognostic value in children with pertussis. Key Words: Mycoplasma pneumoniae, viruses, infection, cough, child (Pediatr Infect Dis J 2011;30: 1047–1051) P ersistent cough is a common symptom among school-age children, which can lead to considerable parental stress and recurrent medical consultations. 1 Parents of children with persis- tent cough tend to consult when the child appears distressed or unwell and are therefore likely to find precise diagnostic and prognostic information helpful. 2 Most coughs in children are caused by acute respiratory tract infections (RTIs), which usually settle within 2 weeks. 3 However, persistent cough following a RTI is common in children. A multicenter European parent questionnaire survey reported that 12.7% of children 7 to 11 years of age had experienced a persistent cough lasting 3 months or longer during the previous autumn/winter season, 7.6% had a persis- tent productive cough even when they did not have a cold, and 11.5% had a persistent dry cough at night. 4 Children with persistent cough are sometimes diagnosed with asthma. However, asthma is less likely in children with persistent cough that is not accompanied by wheeze or other respiratory symptoms. 5 Persistent or secondary RTIs are likely to account for a substantial proportion of persistent cough in children. In a prospective cohort study of 108 children referred to a tertiary center with persistent cough of at least 3 weeks’ duration, almost 40% were diagnosed with protracted bacterial bronchitis involving a range of respiratory pathogens including Haemophilus influen- zae, Moraxella catarrhalis, and Streptococcus pneumoniae. 6 In community studies, various bacterial and viral infections have been implicated in childhood persistent cough. These include Bordetella pertussis (pertussis), 7–9 Mycoplasma pneumoniae (Mp), 8 –10 respiratory syncytial virus, and influenza viruses. 9,10 Most acute RTIs are caused by respiratory viruses. 11 However, Mp is one of the most common bacterial causes of RTIs in children, and its highest incidence is found in the 5- to 9-year age group (4 per 1000 children per year). 12 Between October 2001 and March 2005, we prospectively recruited a cohort of 179 children who presented in UK primary care with persistent cough lasting 2 weeks or longer. We found that 37% had evidence of recent pertussis infection based on serology, and that duration of cough in children with pertussis was signifi- cantly longer than that in children without pertussis. 7 We also sought consent to obtain nasopharyngeal aspirates (NPAs) from these children, but have not previously analyzed or reported these. In this study, we retrospectively analyzed blood samples, NPAs, and cough duration data from this cohort. Our objectives were to estimate the prevalence of Mp, compare duration of cough between children with Mp and pertussis, and to determine whether the presence of respiratory viruses further prolongs the duration of cough in children with these infections. MATERIALS AND METHODS We performed a retrospective analysis of a previously recruited cohort of children 5 to 16 years of age who presented to their general practitioner with a cough lasting 14 days or longer, which was either unexplained or triggered by an acute RTI. Children were prospectively recruited from 18 general practices in Oxfordshire. We sought consent to obtain blood and NPA samples from each child. For children who had been coughing for between 14 and 28 days at the time of study entry, we sought consent to obtain a second blood sample 4 to 6 weeks after the initial sample. 7 Accepted for publication July 14, 2011. From the *Department of Primary Health Care, University of Oxford, Oxford, United Kingdom; †Respiratory and Systemic Infection Laboratory, London Health Protection Agency, London, United Kingdom; and ‡Respiratory Virus Unit, Virus Reference Department, London Health Protection Agency, London, United Kingdom. Supported by the National Institute for Health Research (to K.W.). The authors have no other funding or conflicts of interest to disclose. Address for correspondence: Kay Wang, MRCGP, Department of Primary Health Care, University of Oxford, 23-38 Hythe Bridge St, Oxford, United Kingdom OX1 2ET. E-mail: kay.wang@phc.ox.ac.uk. Copyright © 2011 by Lippincott Williams & Wilkins ISSN: 0891-3668/11/3012-1047 DOI: 10.1097/INF.0b013e31822db5e2 The Pediatric Infectious Disease Journal • Volume 30, Number 12, December 2011 www.pidj.com | 1047