Molecular Analysis of pbp2b in Streptococcus pneumonia Isolated From Clinical and Normal Flora Samples

Abstract

Streptococcus pneumoniae is an important bacterial pathogen responsible for respiratory infections, bacteraemia, and meningitis remains an important cause of disease and mortality in infants and younger children around the world, with penicillin being considered the drug of choice for the treatment of infections. However, penicillin-resistant S. pneumonia is now becoming endemic worldwide. In this study, a total of 80 pneumococcal isolates were collected from different clinical sources as well as normal flora. These isolates were subjected to antimicrobial susceptibility testing and MIC determination. The penicillin-binding proteins, pbp2b, were amplified by PCR, and they were sequenced. The genetic relationship of the penicillin-resistant isolates was performed by BOX PCR. Overall, 36 pneumococcal (45 %) isolates were found to be resistant to penicillin with different MICs. The majority of them (80 %) were intermediately resistant with MIC of 0.12-1 µg/ml, whereas 20 % of isolates were penicillin resistant with MICs of >2 µg/ml. The results identified seven groups which were based on the amino acid substitutions of pbp2b. Sequencing analysis revealed that the most prevalent mutation was the substitution of Adenine for Thymine at the position 445 which is next to the second PBP2b-conserved motif (SSN). This study indicates that resistance to penicillin appears to be dependent on specific mutations in pbp2b, and the substitution in S620 → T near to the third PBP2b-conserved motif appears to be important in developing highly antibiotic-resistant isolates. Moreover, there was a positive correlation between the mutations in pbp2b gene and MIC.

<p>Serotype Distribution and Antibiotic Susceptibility of <em>Streptococcus pneumoniae</em> Isolates in Tehran, Iran: A Surveillance Study</p>

“…The resistance rate to penicillin has increased over the study periods, 1.5 times higher than other recent study in Iran. 33 Serotype 23F was the most common serotype showing resistance to penicillin, while many countries have reported increasing prevalence of resistant NVTs following PCV-13, such as 23A, 15B, and 15C. 34 Furthermore, non-susceptibility rate to ceftriaxone has increased slightly, compared to the previous study in the same area in 2017.…”

Determination of Characteristics of Erythromycin Resistant Streptococcus pneumoniae with Preferred PCV Usage in Iran

“…A written consent, however, was obtained from the control volunteers. Standard microbiological techniques were performed for species identification, including hemolysis, Gram staining, bile solubility and susceptibility to optochin (1μg) disc [9], and identification of isolates was confirmed by lyt A and ply genes using species-specific primers for polymerase chain reaction (PCR) [10]. Serotyping was performed using the Quellung reaction with antisera (Statens Serum Institut Copenhagen, Denmark).…”

Prevalence of Streptococcus pneumoniae in Ventilator-Associated Pneumonia by Real-time PCR

“…In addition, the presence of many respiratory pathogens, including pneumococci as a part of normal respiratory flora in one hand, and the non-quantitative nature of conventional PCR and culture methods on the other hand, have made the issue more complicated. Accordingly, the accurate detection of respiratory infections is still a critical diagnostic problem, and therefore, a method being able to detect and quantify simultaneously the causative pathogen is appreciable (22,24,25). To overcome these limitations, due to the ability of diagnostic species-specific real-time PCR, the present study used a quantitative real-time PCR for detecting and quantifying of Pneumococcal VAP with advantages of saving time and analyzing directly on clinical VAP specimen.…”