Assessing the diagnostic accuracy of PCR-based detection of Streptococcus pneumoniae from nasopharyngeal swabs collected for viral studies in Canadian adults hospitalised with community-acquired pneumonia: a Serious Outcomes Surveillance (SOS) Network of the Canadian Immunization Research (CIRN) study

Utility of Polymerase Chain Reaction in Nasopharyngeal Swabs for Identifying Respiratory Bacteria Causing Community-Acquired Pneumonia

Timely identification of a pathogen in lower respiratory tract infections (LRTI) can support appropriate antibiotics use. The difficulty of obtaining lower respiratory tract (LRT) samples limits the utility of point-of-care syndromic molecular assays. We assessed the performance of the FilmArray Pneumonia plus panel (FilmArray PP) in nasopharyngeal (NP) swab for detection of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Patients in the study included retrospectively consenting adults who attended the emergency department of Lausanne University Hospital between February 2019 and August 2020 for a community-acquired LRTI, with available NP swab and a high-quality LRT sample. These samples were tested with the FilmArray PP (cutoff of ≥10⁴ copies/mL). Positive (PPA) and negative percent agreement (NPA) of FilmArray PP in NP swab were calculated, using (i) FilmArray PP in LRT sample and (ii) standard microbiological tests as reference standards. To assess the performance of a lower detection cutoff, NP samples were also tested with an in-house PCR (cutoff of ≥10 copies/mL) for S. pneumoniae and H. influenzae. Overall, 118 patients were included. FilmArray PP in LRT sample and standard microbiology tests detected S. pneumoniae in 19/118 and 12/118, H. influenzae in 44/118 and 19/118, and M. catarrhalis in 14/118 and 0/118, respectively. Using LRT FilmArray PP as reference, PPA and NPA of FilmArray PP on NP were 58% and 100% for S. pneumoniae, 61% and 100% for H. influenzae, and 57% and 99% for M. catarrhalis. Using standard diagnostic tests as reference, PPA and NPA were 58% and 96% for S. pneumoniae, 74% and 87% for H. influenzae, and indefinite and 92% for M. catarrhalis. Using a lower cutoff on NP (≥10² copies/mL), PPA was 68% for S. pneumoniae and 77% for H. influenzae with LRT FilmArray PP as reference. FilmArray PP in NP swabs has a limited PPA for identifying the most common etiologies of community-acquired LRTI irrespective of the reference standard, preventing its use for withholding antibiotics. The PCR detection cutoff does not explain the low PPA. The excellent NPA suggests the use of NP PCR results for rapidly targeted antimicrobial therapy.

IMPORTANCE Timely identification of a pathogen in patients with lower respiratory tract infections is of paramount importance to avoid inappropriate antibiotic prescription. We aimed to evaluate the performance of a rapid syndromic molecular assay in nasopharyngeal swabs for identifying the most common bacterial causes of lower respiratory tract infections in adults (Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis). Our data show that nasopharyngeal molecular assay has a good concordance with lower respiratory tract sample when positive but not when negative. A positive result is therefore concordant with a lower respiratory tract infection and can be used to target antibiotics. Nevertheless, a negative result does not have a good concordance, so it cannot be used to withhold antibiotics. Our findings illustrate the potential utility of these easily collected samples for the management of patients with lower respiratory tract infections.

Multiplex polymerase chain reaction detection of Streptococcus pneumoniae and Haemophilus influenzae and their antibiotic resistance in patients with community-acquired pneumonia from southwest Iran

BACKGROUND

This study aimed to evaluate the occurrence of Streptococcus pneumoniae and Haemophilus influenzae in sputum of patients with community-acquired pneumonia (CAP) using culture and multiplex polymerase chain reaction (M-PCR) methods and to survey the antibiotic resistance patterns of aforesaid isolates.

RESULT

In total, 23.9 % (n = 22/92) of sputum samples showed positive results in the culture method. S. pneumoniae and H. influenzae were isolated from 15 (16.3 %) and 7 (7.6%) samples, respectively. Using M-PCR, 44 (47.8 %) samples were positive for S. pneumoniae and H. influenzae. Of these, S. pneumoniae and H. influenzae were detected in 33 (35.8%) and 11 (11.9%) of the sputum samples, respectively. The sensitivity, specificity, and accuracy rates of PCR in detection of S. pneumoniae in comparison with culture method were 100, 76.6, and 83.6%, respectively. While, the sensitivity, specificity, and accuracy rates of PCR in detection of H. influenzae in comparison with culture method were 100, 95.3, and 95.8%, respectively. Out of 11 isolates of H. influenzae, two strains confirmed as H. influenzae type b (Hib) and 3 isolates were type f. However, 6 isolates were non-typable. The co-trimoxazole and amoxicillin/clavulanate were the less effective antibiotics against S. pneumonia and H. influenzae, respectively. Ceftriaxone with 13.3% resistance rates was the most effective antibiotic against S. pneumoniae, while, clarithromycin, ceftriaxone, and gentamicin with resistance rates of 28.6% for each one were the most effective chemicals against H. influenzae isolates.

CONCLUSION

In this study, the prevalence of S. pneumoniae was more than H. influenzae using culture and M-PCR methods. The M-PCR provided better efficiency in detecting the bacterial agents in CAP patients compared to culture method. This method can improve the early detection of pathogens contributed to CAP. The drug resistant S. pneumoniae and H. influenzae indicated the need to develop a codified monitoring program to prevent further spread of these strains.

Acute Respiratory Tract Infections among Hospitalized Palestinian Patients (2011-2016): A Retrospective Study

Respiratory tract infections (RTIs) are a major public health concern. This study aims to investigate the profiles and epidemiological characteristics of acute RTIs and respiratory pathogens in Palestinian hospitalized patients. Clinical samples from hospitalized patients with symptoms of acute RTIs admitted between January 2011 and December 2016 were referred to the Palestinian Central Public Health Laboratory (PHCL) to identify the causative pathogen. Patients' demographic information and the results of the molecular identification were retrieved from the electronic database at the PHCL. A total of 15413 patients with acute RTIs were hospitalized during the study period. The causal agent was identified only in 28.7% of the patients. Overall, influenza viruses were the most common cause of RTIs among hospitalized Palestinian patients in the West Bank. Children and elderlies were the most affected with RTIs. The elderly population (≥60 years old) had the highest rates. After influenza A virus, respiratory syncytial virus (RSV), and Bordetella pertussis (B. pertussis) were the most common causes of acute RTIs among hospitalized Palestinian patients. Children showed the highest hospitalization rates for RSV, B. pertussis, adenovirus, enterovirus, and Streptococcus pneumoniae. On the other hand, elderlies had the highest rates of influenza. Outbreaks of RTIs occurred mainly during winter (between December and March). The resurgence of B. pertussis in spite of vaccination is alarming and requires further investigation.

Identification of Streptococcus pneumoniae and other Mitis streptococci: importance of molecular methods

The Mitis group of streptococci includes an important human pathogen, Streptococcus pneumoniae (pneumococcus) and about 20 other related species with much lower pathogenicity. In clinical practice, some representatives of these species, especially Streptococcus pseudopneumoniae and Streptococcus mitis, are sometimes mistaken for S. pneumoniae based on the results of classical microbiological methods, such as optochin susceptibility and bile solubility. Several various molecular approaches that address the issue of correct identification of pneumococci and other Mitis streptococci have been proposed and are discussed in this review, including PCR- and gene sequencing-based tests as well as new developments in the genomic field that represents an important advance in our understanding of relationships within the Mitis group.