The Role of Chlamydia in Upper Respiratory Tract Infections

Microbiology of Acute Maxillary Sinusitis in Children

OBJECTIVES/HYPOTHESIS

Acute rhinosinusitis is a frequent common cold-related complication in children. Despite the need for appropriate treatment, its underlying microbiology remains unclear. This study aimed to investigate the microbiology of acute rhinosinusitis in children.

STUDY DESIGN

Prospective non controlled study.

METHODS

Thirty-one pediatric acute maxillary sinusitis patients with severe symptoms were assessed. The subjects were 17 males and 14 females aged 5 to 14 years (mean age, 9.1 years). Maxillary sinus aspirates were collected and cultured, with subsequent viral and bacterial polymerase chain reaction (PCR) analysis. Bacteria were analyzed using culturing and PCR, and viruses were analyzed using PCR. The PCR kits used identify 18 types of respiratory viruses and 13 types of bacteria.

RESULTS

At least one pathogen was detected in 30 of 31 aspirates (97%) using PCR, and none of the aspirates contained respiratory viruses alone. Ten aspirates (32%) contained both viruses and bacteria. The most common viruses detected were rhinovirus (13%) and influenza virus (10%). The most common bacteria were Haemophilus influenzae (45%), Streptococcus pneumoniae (32%), Moraxella catarrhalis (16%), and Chlamydophila pneumoniae (13%). Bacteria were found in 21 of 31 cases (68%) via bacterial culturing. Culturing revealed that H influenzae was the most common pathogen (42%).

CONCLUSIONS

In pediatric acute maxillary sinusitis, respiratory bacteria were detected in 65% of the sinus aspirates and both bacteria and viruses in 32%. The most common viruses were rhinovirus and influenza virus, and the most common bacteria were H influenzae and S pneumoniae. Viral and bacterial PCR is useful for accurately investigating the microbiology in pediatric sinusitis.

LEVEL OF EVIDENCE

Level 3. Laryngoscope, 2021.

Chronic Pharyngitis: Role of Atypical Organisms

Background

Bacteria including Chlamydophila pneumoniae, Mycoplasma pneumoniae, and anaerobic bacteria such as Fusobacterium necrophorum have been implicated as etiological agents of chronic pharyngitis in Western literature. Because there are no data regarding this from India, the authors undertook this study.

Study Design

Prospective case-control study.

Setting

Tertiary-level medical college and hospital.

Method

In total, 343 consecutive adults with persistent throat pain and/or irritation (duration ≥3 months) were screened for known causes of pharyngitis by a thorough clinical and endoscopic examination. In 71 patients, the evaluation performed was unable to determine any cause, and these were considered cases. An enzyme-linked immunosorbent assay test to detect IgA and IgG antibodies to C pneumoniae and M pneumoniae was performed on 66 of these cases and 62 controls. The posterior pharyngeal swabs taken from both the cases and controls were subjected to aerobic and anaerobic culture.

Results

Individuals with chronic pharyngitis had a 3.43 times odds of being seropositive for C pneumoniae as compared with controls ( P = .001; odds ratio = 3.43). Aerobic organisms and M pneumoniae did not seem to be significant etiological agents for chronic pharyngitis. On the contrary, isolation of Fusobacterium spp was found to be significantly more in controls as compared with cases.

Conclusion

This study suggests an association between IgA antibodies to C pneumoniae and chronic pharyngitis. Further studies using more specific tests combined with long-term follow-up are needed to confirm these findings.

Antibody response to chlamydiae in children with asthma and respiratory illness

No relation between the occurrence of antibodies to chlamydial agents and asthma in children was found. In asthmatic children, the antibodies to Chlamydia trachomatis occurred in 3.1% and to Chlamydophila pneumoniae in 22.7%, whereas in a control group of children without asthma or other allergic disease in 2.3% and 24.0%, respectively. The occurrence of antibodies of IgA and IgG classes to C. pneumoniae was also very similar; its rise was age-dependent. On the other hand, in the group of children in a pre-school age with respiratory tract infection, anti-chlamydial antibodies were demonstrated significantly more often (18.5% of IgG antibodies to C. trachomatis, 20.0% of IgM antibodies to both C. trachomatis and C. pneumoniae) than in those suffering from other, non-respiratory illness (3.9% of the former and 5.9% of the latter antibodies). However, in these children, we did not succeed in detection of C. trachomatis in conjunctival and nasopharyngeal smears by PCR. Nevertheless, chlamydial agents (C. trachomatis in infants, C. pneumoniae in pre-school children) should be taken into consideration in a differential diagnosis of respiratory tract inflammation.

Higher incidence of persistent chronic infection of Chlamydia pneumoniae among coronary artery disease patients in India is a cause of concern

Background

There is growing evidence that Chlamydia pneumoniae may be involved in the pathogenesis of atherosclerosis, as several studies have demonstrated the presence of the organism in atherosclerotic lesions. C. pneumoniae infections, which are especially persistent infections, have been difficult to diagnose either by serological methods or isolation of the organism from the tissue. Nucleic Acid Amplification tests (NAATs) has emerged as an important method for detecting C. pneumoniae. Inspite of high prevalence of C. pneumoniae specific antibodies in coronary heart disease patients, direct detection of C. pneumoniae in circulating blood of coronary artery disease (CAD) patients by sensitive nucleic acid amplification tests nested PCR (nPCR), multiplex PCR (mPCR) has not been carried out is required. Further correlation of the presence of C. pneumoniae in blood of CAD patients with C. pneumoniae specific IgA and IgG antibodies, which may indicative of the status of infection with the progression of atherosclerosis. This will help in order to prepare strategies for the antibiotic intervention to avoid the progression towards CAD.

Methods

Venous blood was obtained from 91 CAD patients and 46 healthy controls. Nucleic acid amplification tests viz. nested -, semi-nested – and multiplex PCR were used for detection of C. pneumoniae. ELISA carried out prevalence of C. pneumoniae specific IgG and IgA antibodies.

Results

29.67% (27/91) patients were positive for C. pneumoniae using nested PCR. The sensitivity and specificity of semi-nested and multiplex PCR were 37.03%, 96.96% and 22.22%, 100% with respect to nested PCR. Positive nPCR patients were compared with presence of C. pneumoniae specific IgA, IgA+IgG and IgG antibodies. Among 27 (29.67%) nPCR C. pneumoniae positive CAD patients, 11(12%) were IgA positive, 13(14.2%) were IgA+IgG positive and only1 (1.1%) was IgG positive. A significant presence of C. pneumoniae was detected in heavy smokers, non-alcoholics and with family histories of diabetes and blood pressure group of CAD patients by nPCR.

Conclusion

The results indicate synergistic association of C. pneumoniae infection and development of CAD with other risk factors. We also detected increased positivity for C. pneumoniae IgA than IgG in nPCR positive CAD patients. Positive nPCR findings in conjunction with persisting high C. pneumoniae specific antibody strongly suggest an ongoing infection.

Aetiology of acute pharyngitis: the role of atypical bacteria

In order to establish the role of atypical bacteria and compare characteristics of different infectious agents in acute pharyngitis, 127 patients with acute pharyngitis (66 males; median age, 5.33 years; range, 6 months to 14 years) and 130 healthy subjects of similar sex and age were studied. Serology with paired samples and PCR on nasopharyngeal aspirates and throat cultures were used to identify bacteria and viruses. Viruses were identified in 43 patients (33.8%) and five controls (3.8%; P < 0.0001), potential bacterial pathogens in 34 patients (26.8%) and 26 controls (20%; P = 0.256) and mixed viral/bacterial pathogens in 26 patients (20.5%) and none of the controls (P < 0.0001). The main aetiological agents were adenovirus, respiratory syncytial virus (RSV), Mycoplasma pneumoniae, Streptococcus pyogenes and Chlamydia pneumoniae. M. pneumoniae was the agent found most frequently as a single pathogen. A history of recurrent pharyngitis, having older siblings and a negative outcome were significantly more common among patients with acute M. pneumoniae infection than among those with infections due to other pathogens or healthy controls. This study demonstrates that: (i) adenovirus and RSV have a prominent role in acute pharyngitis; (ii) S. pyogenes is found frequently, but it is not possible to distinguish simple carriers from patients with a true infection; (iii) M. pneumoniae appears to be able to cause acute pharyngitis per se; and (iv) C. pneumoniae seems to be mainly a co-pathogen. To avoid the risk of an incorrect therapeutic approach, simple laboratory investigations that allow rapid identification of M. pneumoniae infections are urgently needed.

Role of atypical bacterial infection of the lung in predisposition/protection of asthma

Asthma is a common inflammatory disease of the airways that results in airway narrowing and wheezing. Allergic asthma is characterised by a T-helper cell-type (Th) 2 response, immunoglobulin (Ig) E production, and eosinophilic influx into the airways. Recently, many clinical studies have implicated Mycoplasma pneumoniae and Chlamydia pneumoniae in the development and exacerbation of both chronic and acute asthma. It is widely accepted that M. pneumoniae and C. pneumoniae infections require Th1 immunity for clearance; therefore, according to the hygiene hypothesis, these infections should be protective against asthma. Here, we review the clinical evidence for the association and mechanisms of predisposition to and protection against asthma by these infections. We will examine the following question: Is it the absence of infection or the age of the individual on infection that confers susceptibility or resistance to asthma and does this vary between normal and predisposed individuals? We put forward a hypothesis of the effects of these infections on the development and prevention of asthma and how novel preventative and treatment strategies involving these microbes may be targeted against asthma.

Mycoplasma pneumoniae and Chlamydia pneumoniae cause lower respiratory tract disease in paediatric patients

New studies suggest that Mycoplasma pneumoniae and Chlamydia pneumoniae play a more significant role as causes of lower respiratory tract infections in childhood than was previously thought. In particular, the incidence of infections caused by these pathogens is high in children aged less than 5 years, the infections themselves seem to be a possible cause of wheezing, and may present a more complicated course when not treated with adequate antimicrobial agents. However, despite the increasing pathogenic significance of M. pneumoniae and C. pneumoniae, progress in fighting them is hampered by the lack of rapid and standardized diagnostic methods. This not only makes it practically impossible for practitioners to make a specific microbiological diagnosis, but has also had an adverse effect on treatment trials and has generated some questionable results. Carefully randomized and controlled trials are clearly needed to examine the effectiveness of different antibiotics against M. pneumoniae or C. pneumoniae and the optimal duration of therapy in various patient populations.

Development and evaluation of real-time PCR-based fluorescence assays for detection of Chlamydia pneumoniae

Chlamydia pneumoniae is an important respiratory pathogen recently associated with atherosclerosis and several other chronic diseases. Detection of C. pneumoniae is inconsistent, and standardized PCR assays are needed. Two real-time PCR assays specific for C. pneumoniae were developed by using the fluorescent dye-labeled TaqMan probe-based system. Oligonucleotide primers and probes were designed to target two variable domains of the ompA gene, VD2 and VD4. The limit of detection for each of the two PCR assays was 0.001 inclusion-forming unit. Thirty-nine C. pneumoniae isolates obtained from widely distributed geographical areas were amplified by the VD2 and VD4 assays, producing the expected 108- and 125-bp amplification products, respectively. None of the C. trachomatis serovars, C. psittaci strains, other organisms, or human DNAs tested were amplified. The amplification results of the newly developed assays were compared to the results of culturing and two nested PCR assays, targeting the 16S rRNA and ompA genes. The assays were compared by testing C. pneumoniae purified elementary bodies, animal tissues, 228 peripheral blood mononuclear cell (PBMC) specimens, and 179 oropharyngeal (OP) swab specimens obtained from ischemic stroke patients or matched controls. The real-time VD4 assay and one nested PCR each detected C. pneumoniae in a single, but different, PBMC specimen. Eleven of 179 OP specimens (6.1%) showed evidence of the presence of C. pneumoniae in one or more tests. The real-time VD4 assay detected the most positive results of the five assays. We believe that this real-time PCR assay offers advantages over nested PCR assays and may improve the detection of C. pneumoniae in clinical specimens.

Emerging role of Mycoplasma pneumoniae and Chlamydia pneumoniae in paediatric respiratory-tract infections

Increased use of specialised diagnostic techniques over the past 10 years has allowed considerable new information to be obtained concerning Mycoplasma pneumoniae and Chlamydia pneumoniae infections. In children, these pathogens seem to have a more important role in causing respiratory-tract infections than previously thought; they have been associated with wheezing, and they are also frequent in children aged under 5 years. Contrary to original belief, no clinical, laboratory, or radiological findings seem to be unique to M. pneumoniae or C. pneumoniae; furthermore, there is no rapid and cost-effective diagnostic test capable of identifying these pathogens. Appropriate antimicrobial treatment of the infections they cause is needed to reduce the recurrent episodes of wheezing and other respiratory symptoms, to decrease morbidity, and to avoid the spread of the pathogens. However, a number of therapeutic issues remain unsolved.