Evaluation of Chlamydia pneumoniae and Mycoplasma pneumoniae as etiologic agents of persistent cough in adolescents and adults

A Compendium for Mycoplasma pneumoniae

Historically, atypical pneumonia was a term used to describe an unusual presentation of pneumonia. Currently, it is used to describe the multitude of symptoms juxtaposing the classic symptoms found in cases of pneumococcal pneumonia. Specifically, atypical pneumonia is a syndrome resulting from a relatively common group of pathogens including Chlamydophila sp., and Mycoplasma pneumoniae. The incidence of M. pneumoniae pneumonia in adults is less than the burden experienced by children. Transmission rates among families indicate children may act as a reservoir and maintain contagiousness over a long period of time ranging from months to years. In adults, M. pneumoniae typically produces a mild, “walking” pneumonia and is considered to be one of the causes of persistent cough in patients. M. pneumoniae has also been shown to trigger the exacerbation of other lung diseases. It has been repeatedly detected in patients with bronchitis, asthma, chronic obstructive pulmonary disorder, and cystic fibrosis. Recent advances in technology allow for the rapid diagnosis of M. pneumoniae through the use of polymerase chain reaction or rapid antigen tests. With this, more effort has been afforded to identify the causative etiologic agent in all cases of pneumonia. However, previous practices, including the overprescribing of macrolide treatment in China and Japan, have created increased incidence of macrolide-resistant M. pneumoniae. Reports from these countries indicate that >85% of M. pneumoniae pneumonia pediatric cases are macrolide-resistant. Despite its extensively studied past, the smallest bacterial species still inspires some of the largest questions. The developments in microbiology, diagnostic features and techniques, epidemiology, treatment and vaccines, and upper respiratory conditions associated with M. pneumoniae in adult populations are included within this review.

Eosinophilic airway inflammation is common in subacute cough following acute upper respiratory tract infection

BACKGROUND AND OBJECTIVE

Patients presenting with refractory postinfectious cough may respond to glucocorticosteroids but it is unclear whether airway eosinophilic inflammation exists in those patients. We aimed to determine the airway inflammation and causes of subacute cough following acute upper respiratory tract infection (AURTI).

METHODS

One hundred and sixteen patients with persistent cough lasting 3-8 weeks after upper respiratory tract infection were evaluated with differential cell count in induced sputum, spirometry and methacholine bronchial challenge testing.

RESULTS

In patients with subacute cough, sputum eosinophilia (median 8.5%,3.0-73.0%) was identified in 35 (33.6%) patients, 22 (18.5%) without bronchial hyperresponsiveness (BHR) were diagnosed as non-asthmatic eosinophilic bronchitis (NAEB), 13 (14.3%) of whom with BHR were diagnosed as cough variant asthma (CVA). Cough in patients with sputum eosinophilia improved after treatment with corticosteroids. Compared with postinfectious cough (PIC) and NAEB, CVA had significantly higher median eosinophil count in induced sputum (0.5% vs 7.5% vs 20.0%, P < 0.01). MMEF in CVA was significantly lower than PIC and NAEB (P < 0.05). The common causes of subacute cough following acute upper respiratory tract infection (AURTI) were PIC (37.8%), NAEB (18.5%), CVA (14.3%) and upper airway cough syndrome (UACS) (10.1%). Atopic cough (AC) (5.2%) and gastroesophageal reflux-related cough (GERC) (3.4%) were less common in subacute cough following AURTI, while 9 (7.8%) patients had unexplained cough.

CONCLUSION

Subacute cough following AURTI can be attributed to different entities, eosinophilic airway inflammation is common. Induced sputum should be considered when evaluating patients with subacute cough following acute upper respiratory tract infection.

Role of Atypical Pathogens and the Antibiotic Prescription Pattern in Acute Bronchitis: A Multicenter Study in Korea

The role of atypical bacteria and the effect of antibiotic treatments in acute bronchitis are still not clear. This study was conducted at 22 hospitals (17 primary care clinics and 5 university hospitals) in Korea. Outpatients (aged ≥ 18 yr) who had an acute illness with a new cough and sputum (≤ 30 days) were enrolled in 2013. Multiplex real-time polymerase chain reaction (RT-PCR) was used to detect five atypical bacteria. A total of 435 patients were diagnosed as having acute bronchitis (vs. probable pneumonia, n = 75), and 1.8% (n = 8) were positive for atypical pathogens (Bordetella pertussis, n = 3; B. parapertussis, n = 0; Mycoplasma pneumoniae, n = 1; Chlamydophila pneumoniae, n = 3; Legionella pneumophila, n = 1). Among clinical symptoms and signs, only post-tussive vomiting was more frequent in patients with atypical pathogens than those without (P = 0.024). In all, 72.2% of the enrolled patients received antibiotic treatment at their first visits, and β-lactams (29.4%) and quinolones (20.5%) were the most commonly prescribed agents. In conclusion, our study demonstrates that the incidence of atypical pathogens is low in patients with acute bronchitis, and the rate of antibiotic prescriptions is high.

Novel aspects on the pathogenesis of Mycoplasma pneumoniae pneumonia and therapeutic implications

Mycoplasma pneumoniae (Mp) is a leading cause of community acquired pneumonia. Knowledge regarding Mp pneumonia obtained from animal models or human subjects has been discussed in many different reports. Accumulated expertise concerning this critical issue has been hard to apply clinically, and potential problems may remain undiscovered. Therefore, our multidisciplinary team extensively reviewed the literature regarding Mp pneumonia, and compared findings from animal models with those from human subjects. In human beings, the characteristic pathological features of Mp pneumonia have been reported as alveolar infiltration with neutrophils and lymphocytes and lymphocyte/plasma cell infiltrates in the peri-bronchovascular area. Herein, we demonstrated the novel aspects of Mp pneumonia that the severity of the Mp pneumonia seemed to depend on the host innate immunity to the Mp, which might be accelerated by antecedent Mp exposure (re-exposure or latent respiratory infection) through up-regulation of Toll-like receptor 2 expression on bronchial epithelial cells and alveolar macrophages. The macrolides therapy might be beneficial for the patients with macrolide-resistant Mp pneumonia via not bacteriological but immunomodulative effects. This exhaustive review focuses on pathogenesis and extends to some therapeutic implications such as clarithromycin, and discusses the various diverse aspects of Mp pneumonia. It is our hope that this might lead to new insights into this common respiratory disease.

Evaluation and treatment of chronic cough

Chronic cough is a frustrating and common problem, resulting in significant psychological and physical sequelae as well as enormous financial costs in terms of health care expense and time lost from work. Decreased QoL and depression are common. However, using a systematic approach, including assessing whether the patient uses ACE-I and cigarettes, excluding the presence of red flags and risk factors for life-threatening diseases, and obtaining and normal chest radiograph, more than 90% of cases of chronic cough are diagnosed as being caused by UACS, asthma, or GERD. It is recommended to address these conditions sequentially, starting with UACS. Nonasthmatic eosinophilic bronchitis and pertussis infections are unrecognized by primary care providers and should be considered after UACS, asthma, and GERD have been addressed. Finally, cough hypersensitivity syndrome is a new area of research and has been hypothesized to be the underlying factor in many cases of chronic cough, regardless of the inciting factor. More clinical research is needed to further elucidate the cough reflex pathway and the factors involved in modulating its sensitivity, which may eventually lead to new antitussive therapeutics.

Causal inference regarding infectious aetiology of chronic conditions: a systematic review

BACKGROUND

The global burden of disease has shifted from communicable diseases in children to chronic diseases in adults. This epidemiologic shift varies greatly by region, but in Europe, chronic conditions account for 86% of all deaths, 77% of the disease burden, and up to 80% of health care expenditures. A number of risk factors have been implicated in chronic diseases, such as exposure to infectious agents. A number of associations have been well established while others remain uncertain.

METHODS AND FINDINGS

We assessed the body of evidence regarding the infectious aetiology of chronic diseases in the peer-reviewed literature over the last decade. Causality was assessed with three different criteria: First, the total number of associations documented in the literature between each infectious agent and chronic condition; second, the epidemiologic study design (quality of the study); third, evidence for the number of Hill's criteria and Koch's postulates that linked the pathogen with the chronic condition. We identified 3136 publications, of which 148 were included in the analysis. There were a total of 75 different infectious agents and 122 chronic conditions. The evidence was strong for five pathogens, based on study type, strength and number of associations; they accounted for 60% of the associations documented in the literature. They were human immunodeficiency virus, hepatitis C virus, Helicobacter pylori, hepatitis B virus, and Chlamydia pneumoniae and were collectively implicated in the aetiology of 37 different chronic conditions. Other pathogens examined were only associated with very few chronic conditions (≤ 3) and when applying the three different criteria of evidence the strength of the causality was weak.

CONCLUSIONS

Prevention and treatment of these five pathogens lend themselves as effective public health intervention entry points. By concentrating research efforts on these promising areas, the human, economic, and societal burden arising from chronic conditions can be reduced.

Chlamydophila pneumoniae

Chlamydophila pneumoniae is estimated to cause about 10% of community-acquired pneumonia (CAP) cases and 5% of bronchitis cases, although most patients with C pneumoniae infection are asymptomatic, and the course of respiratory illness is relatively mild. The incubation period of C pneumoniae infection is around 21 days, and such symptoms as cough and malaise show a gradual onset, yet may persist for several weeks or months despite appropriate antibiotic therapy. Diagnosis by nasopharyngeal specimen culture, serum antibody titers, or molecular techniques is usually delayed with respect to the onset of symptoms, antibiotic treatment, or disease resolution and there is no accurate, standardized, commercial US Food and Drug Administration-cleared diagnostic method available. Erythromycin, tetracycline, and doxycycline are used as first-line therapy, although some investigators report no clinical or survival benefits from treating CAP caused by atypical pathogens. Meanwhile, adequate prospective studies have met with ethical and logistic barriers. Despite these limitations, North American guidelines recommend the antimicrobial treatment of patients with acute C pneumoniae respiratory infection.

A multiplex PCR assay for the detection of respiratory bacteriae in nasopharyngeal smears from children with acute respiratory disease

To elucidate the frequency of infections with pathogenic respiratory bacteriae during an inter-epidemic period a multiplex PCR assay was used to screen nasopharyngeal smears for the presence of DNA specific for Bordetella pertussis, Bordetella parapertussis, Chlamydophila pneumoniae and Mycoplasma pneumoniae. 187 samples from children aged 2-14 y were analysed with this method in addition to classical bacteriology and compared to results obtained with commercially available PCR kits for each single parameter. From 82 samples positive by bacteriology, 8 (4.3%) were also positive by PCR, whereas from 105 negative samples, 12 (6.4%) were positive only by PCR. From the total of 20 samples positive by PCR, 4 were found to be positive for M. pneumoniae, 6 for B. pertussis, 3 for B. parapertussis and 7 for both B. pertussis and B. parapertussis. Multiplex PCR is a very useful approach for the diagnosis of bacterial infections not detectable by classical bacteriology. In some patients, PCR was the only method giving a positive result, and in others double infections were diagnosed only because of the PCR contribution. Combination of classical bacteriology with multiplex PCR allows a precise diagnosis of infections in the upper respiratory tract, resulting in a more effective therapy.

Frequency of Chlamydia pneumoniae and Mycoplasma pneumoniae infections in children

OBJECTIVE

Chlamydia pneumoniae and Mycoplasma pneumoniae are among the most important pathogens of acute respiratory infections in children between the ages of 5 and 15 years. We aimed to investigate seasonal frequency of respiratory infections caused by C. pneumoniae and M. pneumoniae, frequency of coinfection, clinical findings and to determine relationship between clinical findings and laboratory results.

MATERIAL AND METHODS

Total of 284 patients (ranging 5-15 years of age), admitted to out-patient clinic with symptoms of respiratory tract infections between January 2004 and June 2005, were enrolled in the study. IgA, IgG and IgM antibodies against C. pneumoniae were quantitatively detected in all serum samples by using microimmunofluorescence (MIF). For the M. pneumoniae infection an IgM titer in the ELISA test were analyzed. Nasopharyngeal smear samples were collected for PCR detection.

RESULTS

Mean age was 8 +/- 2.2 (range 5-14) years. Mycoplasma pneumoniae IgM in 86 (30.2%) cases, C. pneumoniae IgM in one (0.3%) case, IgA in six (2.1%) cases and IgG in 10 (3.5%) cases were found positive. In 10 (3.5%) cases, both C. pneumoniae IgG (a titer of >1/216) and M. pneumoniae IgM were found positive concomitantly. The M. pneumoniae IgM in winter was found significantly higher compared to other seasons. Mycoplasma pneumoniae PCR method was performed on a total of 203 samples in 33 (16.2%) of which M. pneumoniae was found positive. The false positive ratio of PCR technique was found 16.2%. In a total of 217 examined samples by PCR method, the DNA of C. pneumoniae was found positive in two patients.

CONCLUSION

Mycoplasma pneumoniae was a common pathogen in respiratory infections. The otherwise C. pneumoniae infections were rarely seen in children. A Comparison of serology diagnostic tests for M. pneumoniae infections was found more sensitive and specific than PCR.

Mycoplasma pneumoniae and atypical Stevens-Johnson syndrome: a case series

Mycoplasma pneumoniae is a common cause of community-acquired respiratory illness in the adolescent population. Stevens-Johnson syndrome is an extrapulmonary manifestation that has been associated with M. pneumoniae infections. Three adolescent males presented within a 1-month period with M. pneumoniae respiratory illnesses and severe mucositis but without the classic rash typical of Stevens-Johnson. Diagnosis was facilitated by the use of a polymerase chain reaction-based assay. This case series highlights the potential for M. pneumoniae-associated Stevens-Johnson syndrome to occur without rash and supports the use of polymerase chain reaction for early diagnosis.

Serology of Chlamydia pneumoniae in patients with chronic cough

OBJECTIVE AND BACKGROUND

Chronic cough is one of the more common respiratory symptoms. Controversy exists as to whether Chlamydia infection is associated with chronic cough. As such, the association of chronic cough with serological evidence of Chlamydia pneumoniae (C. P) infection and a systemic inflammatory marker was assessed.

METHODS

Thirty-seven patients who visited Kangwon National University Hospital for chronic cough between September 2003 and August 2004 and 37 age-matched healthy controls were evaluated for C. P. antibodies and C-reactive protein. Chronic infection was defined as an IgG or IgA titre between 1:64 and 1:512, and acute infection was defined as IgM=1:16 or IgG titre of=1:512 or IgA=1:512. A nasopharyngeal swab was evaluated for C. P. DNA using the polymerase chain reaction.

RESULTS

The median duration of cough was 3 months (1-240). Nineteen patients (49%) and 19 controls had titres consistent with chronic infection, and the titre difference was not significant (P=0.592). Nine patients and two controls had titres consistent with acute infection (24.3% vs. 5.4%). Acute infection was significantly more prevalent in the patients with chronic cough (P=0.023). There was no difference in the C-reactive protein value (0.13 vs. 0.14, P=0.84). Three patients were positive for C. P. DNA.

CONCLUSION

Acute Chlamydia infection was more prevalent in patients with chronic cough, whereas chronic Chlamydia infection was not. There was no elevation of a systemic inflammatory marker in patients with chronic cough.

Pulmonary disorders in the training room

For the athlete, not only can pulmonary disorders cause significant alterations in training schedules or even prolonged stoppages, they can be life-threatening. Infectious diseases such as acute bronchitis, influenza, and pneumonia conspire to disrupt exercise regimens. Pneumothorax, vocal cord dysfunction, and exercise-induced asthma may present diagnostic and treatment challenges. Obstructive sleep apnea not only causes disruptive symptoms but can be associated with significant cardiovascular morbidity and even mortality. This article addresses the most common pulmonary conditions athletes face and provides a framework for the diagnosis and treatment of these conditions.

Cough in children: when does it matter?

Cough is a common presenting symptom to paediatricians and paediatric respiratory physicians. The causes of chronic cough in childhood are significantly different from those in adults, and a different approach to diagnosis and management is needed. In most cases cause can be identified or a satisfactory label given. This review will cover the approach to cough in children and cover some specific causes of troublesome cough not discussed elsewhere in this mini-symposium.

Chronic cough due to acute bronchitis: ACCP evidence-based clinical practice guidelines

BACKGROUND

The purpose of this review is to present the evidence for the diagnosis and treatment of cough due to acute bronchitis and make recommendations that will be useful for clinical practice. Acute bronchitis is one of the most common diagnoses made by primary care clinicians and emergency department physicians. It is an acute respiratory infection with a normal chest radiograph that is manifested by cough with or without phlegm production that lasts for up to 3 weeks. Respiratory viruses appear to be the most common cause of acute bronchitis; however, the organism responsible is rarely identified in clinical practice because viral cultures and serologic assays are not routinely performed. Fewer than 10% of patients will have a bacterial infection diagnosed as the cause of bronchitis. The diagnosis of acute bronchitis should be made only when there is no clinical or radiographic evidence of pneumonia, and the common cold, acute asthma, or an exacerbation of COPD have been ruled out as the cause of cough. Acute bronchitis is a self-limited respiratory disorder, and when the cough persists for >3 weeks, other diagnoses must be considered.

METHODS

Recommendations for this review were obtained from data using a National Library of Medicine (PubMed) search dating back to 1950, which was performed in August 2004. The search was limited to literature published in the English language and human studies, using search terms such as "cough," "acute bronchitis," and "acute viral respiratory infection."

RESULTS

Unfortunately, most previous controlled trials guiding the treatment of acute bronchitis have not vigorously differentiated acute bronchitis and the common cold, and also have not distinguished between an acute exacerbation of chronic bronchitis and acute asthma as a cause of acute cough. For patients with the putative diagnosis of acute bronchitis, routine treatment with antibiotics is not justified and should not be offered. Antitussive agents are occasionally useful and can be offered as therapy for short-term symptomatic relief of coughing, but there is no role for inhaled bronchodilator or expectorant therapy. Children and adult patients with confirmed and probable whooping cough should receive a macrolide antibiotic and should be isolated for 5 days from the start of treatment; early treatment within the first few weeks will diminish the coughing paroxysms and prevent spread of the disease; the patient is unlikely to respond to treatment beyond this period.

CONCLUSION

Acute bronchitis is an acute respiratory infection that is manifested by cough and, at times, sputum production that lasts for no more than 3 weeks. This syndrome should be distinguished from the common cold, an acute exacerbation of chronic bronchitis, and acute asthma as the cause of acute cough. The widespread use of antibiotics for the treatment of acute bronchitis is not justified, and vigorous efforts to curtail their use should be encouraged.