Clonal spread of highly beta-lactam-resistant Streptococcus pneumoniae isolates in Taiwan

Comparative genomics of invasive Streptococcus pneumoniae CC320/271 serotype 19F/19A before the introduction of pneumococcal vaccine in India

The emergence of multi drug resistant clone CC320 serotype19F/19A and their capsular (cps) antigenic variants due to selective pressures such as vaccine had been reported worldwide. Hence, it is important to identify the prevalent clones, sequence types and cps variants of serotype 19F/19A in India, where PCV13 has been recently introduced. Multi-locus sequence typing (MLST) was performed for all (n = 21) invasive S. pneumoniae isolates of serotype 19A (n = 5) and 19F (n = 16) collected between the years 2012 and 2018 from children less than 5 years. The genome characterization by whole genome sequencing for the Sequence types (STs) 320 and 271(n = 7) were performed and compared with another six Indian WGSs of similar STs available from the GPS platform. The predominant STs in the serotype 19F/19A study isolates were of CC320: ST 320, 236 and 271, associated with PMEN clone Taiwan^19F-14. The WGSs of CC320 study isolates showed high genomic similarity to the Taiwan^19F-14 clone, and the penicillin binding protein (PBP) amino acid sequence similarity was 100% for PBP1A, 93% for PBP 2B and 2X. Whilst PBP comparison with other global MDR ST320 strains revealed that the ST320 clones in India are of low-level penicillin resistance. The presence of a few ST320/19A/19F invasive isolates with high similarity to the Taiwan clone suggests slow and gradual expansion of Taiwan^19F-14 associated CC320 clones in India. Since serotype 19F/19A is covered by PCV13 vaccine, the expansion of 19F/19A cones with non-PCV13 vaccine serotype in India should be monitored.

Selection of appropriate analytical tools to determine the potency and bioactivity of antibiotics and antibiotic resistance

Antibiotics are the chemotherapeutic agents that kill or inhibit the pathogenic microorganisms. Resistance of microorganism to antibiotics is a growing problem around the world due to indiscriminate and irrational use of antibiotics. In order to overcome the resistance problem and to safely use antibiotics, the correct measurement of potency and bioactivity of antibiotics is essential. Microbiological assay and high performance liquid chromatography (HPLC) method are used to quantify the potency of antibiotics. HPLC method is commonly used for the quantification of potency of antibiotics, but unable to determine the bioactivity; whereas microbiological assay estimates both potency and bioactivity of antibiotics. Additionally, bioassay is used to estimate the effective dose against antibiotic resistant microbes.

Simultaneously, microbiological assay addresses the several parameters such as minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC), mutation prevention concentration (MPC) and critical concentration (Ccr) which are used to describe the potency in a more informative way. Microbiological assay is a simple, sensitive, precise and cost effective method which gives reproducible results similar to HPLC. However, the HPLC cannot be a complete substitute for microbiological assay and both methods have their own significance to obtain more realistic and precise results.

Penicillin-Resistant trend of Streptococcus pneumoniae in Asia: A systematic review

The high prevalence of resistance to penicillin by Streptococcus pneumoniaeis considered as a great concern, particularly in Asian countries. The aim of this study was to investigate the changing trend of penicillin-resistant S. pneumoniae (PRSP) in Asia over a 20 years period. A review of the literature was conducted using the PubMed database, Google Scholar, Scopus, two Persian scientific search engines "Scientific Information Database" (www.sid.ir), and "Mag Iran" (www.magiran.com) through 1993 to 2013. Our study provides a unique chance to investigate the changing trend in PSSP in Asia over a 20 years period. Susceptibility rates among different centers in each country varied widely. In Malaysia, the PSSP rate decreased from 97.2% in 1995-1996 to 69% in 2000. In Singapore, PSSP levels decreased from 72.6% in 1997 to 30.5% in 2007-2008. In Iran, PSSP ranged from 0% to 100%. In Taiwan, the rate of PSSP was 60.3% in 1995 and <50% in other years. In Lebanon, the rate of PSSP was less than 50% (ranging from 30.1% to 50%) in all published data. In Hong Kong, the level of penicillin susceptibility decreased from 71.1% during 1993-1995 to less 42% in 2007. Continuous surveillance of resistance data from clinical isolates as well as implementation of strict infection control policies is recommended. More studies are needed for better evaluation PSSP rate in some Asian countries such as Vietnam, Singapore, Philippines, Pakistan, Nepal, Kuwait, Korea and Indonesia.

Expansion and evolution of Streptococcus pneumoniae serotype 19A ST320 clone as compared to its ancestral clone, Taiwan19F-14 (ST236)

BACKGROUND

The Streptococcus pneumoniae serotype 19A sequence type (ST) 320 clone, derived from an international Taiwan(19F)-14 (ST236) clone, has become prevalent in many countries.

METHODS

The dynamics of invasive pneumococcal disease (IPD) were determined using the database of the National Notifiable Disease Surveillance System in Taiwan. The virulence of 19A ST320 and Taiwan(19F)-14 (ST236) were assessed in mice. By constructing an isogenic serotype 19F variant of the 19A ST320 strain (19F ST320), we analyzed the role of capsular type and genetic background on the difference in virulence between 19A ST320 and Taiwan(19F)-14 (ST236).

RESULTS

Between 2008 and 2011, IPD due to serotype 19A increased from 2.1 to 10.2 cases per 100 000 population (P < .001); IPD due to any serotype also significantly increased (P = .01). Most serotype 19A isolates belonged to ST320. Using competition experiments in a murine model of colonization, we demonstrated that 19A ST320 outcompeted Taiwan(19F)-14 (ST236; competitive index, 20.3; P = .001). 19F ST320 was 2-fold less competitive than the 19A ST320 parent (competitive index, 0.47; P = .04) but remained 14-fold more competitive than Taiwan(19F)-14 (ST236; competitive index, 14.7; P < .001).

CONCLUSIONS

Genetic evolution of pneumococcal clones from Taiwan(19F)-14 (ST236) to 19A ST320 has made this pneumococcus better able to colonize of the nasopharynx. This evolution reflects not only a switch in capsular serotype but also changes in other loci.

Regional epidemiology of invasive pneumococcal disease in Asian adults: epidemiology, disease burden, serotype distribution, and antimicrobial resistance patterns and prevention

OBJECTIVES

To summarize published data on the clinical and economic burden, epidemiology, antimicrobial resistance levels, serotype prevalence, and prevention strategies for pneumococcal disease among adults in Asia.

METHODS

We performed a systematic search of the PubMed database for relevant, peer-reviewed articles published between January 1995 and December 2011, covering China, Hong Kong, India, Indonesia, Japan, Malaysia, Pakistan, the Philippines, Singapore, South Korea, Taiwan, Thailand, and Vietnam.

RESULTS

Taiwan and Thailand had the most comprehensive epidemiological data on adult pneumococcal disease. Very little relevant data were found for Indonesia, Pakistan, the Philippines, and Vietnam; surveillance is urgently needed in these countries. The emergence and spread of resistance emphasize the importance of vaccination to prevent infection in adults at increased risk for serious pneumococcal disease. Vaccination policies and opinions on the efficacy of vaccination vary widely in Asian countries, although a new option in the form of a pneumococcal conjugate vaccine is now available.

CONCLUSIONS

Increased awareness of the public health and economic benefits of pneumococcal vaccination is critically needed to help both the public and policymakers in making changes to vaccination policies in the region. Maximizing access to pneumococcal vaccines will decrease the number of hospitalizations, complications, and deaths associated with pneumococcal disease.

Immunogenicity and safety of 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) co-administered with routine childhood vaccines in Taiwan

BACKGROUND/PURPOSE

The immunogenicity and safety of the 10-valent pneumococcal nontypeable Haemophilus influenzae (H. Influenzae) protein D conjugate vaccine (PHiD-CV), co-administered with routine childhood vaccines, were assessed in Taiwanese infants.

METHODS

In this open study, 230 healthy infants were primed with three doses of PHiD-CV (Synflorix) and diphtheria, tetanus, acellular pertussis, hepatitis B (HBV), inactivated poliomyelitis and Haemophilus influenzae type b (Hib) conjugate vaccine (DTPa-HBV-IPV/Hib vaccine) at 1.5, 3 and 6 months of age and two doses of oral human rotavirus vaccine at 1.5 and 3 months. Pneumococcal immune responses were assessed 1 month post-dose three, by 22F-inhibition ELISA and opsonophagocytic activity (OPA) assay. Local and general solicited/unsolicited symptoms and serious adverse events (SAEs) were recorded.

RESULTS

At least 95.4% of participants had an antibody concentration ≥ 0.2 μg/mL against each vaccine serotype. At least 96.1% of participants had an OPA titer ≥ 8 against each vaccine serotype except 6B (87.3%). All infants, but one, were seropositive for antibodies against nontypeable H. influenzae protein D. Immune responses to the co-administered vaccines were good and in line with previous reports. PHiD-CV was well tolerated, with low (≤ 6.3%) incidences of grade 3 solicited local symptoms. The frequencies of general symptoms were in line with other pneumococcal conjugate vaccine studies. There were no systematic increases in incidences of solicited general or local symptoms with successive doses. There were no reports of grade 3 fever (rectal temperature > 40 °C) or SAEs considered to be causally related to vaccination.

CONCLUSION

PHiD-CV co-administered with routine childhood vaccines within the first 6 months of life, was highly immunogenic, and well tolerated in Taiwanese infants.

Clinical and economic burden of community-acquired pneumonia amongst adults in the Asia-Pacific region

Community-acquired pneumonia (CAP) is an important cause of mortality and morbidity amongst adults in the Asia-Pacific region. Literature published between 1990 and May 2010 on the clinical and economic burden of CAP amongst adults in this region was reviewed. CAP is a significant health burden with significant economic impact in this region. Chronic obstructive pulmonary disease, cardiovascular disease, diabetes mellitus and advanced age were risk factors for CAP. Aetiological agents included Streptococcus pneumoniae, Klebsiella pneumoniae, Gram-negative bacteria, Mycobacterium tuberculosis, Burkholderia pseudomallei, Staphylococcus aureus and atypical pathogens (Mycoplasma pneumoniae, Chlamydophila pneumoniae and Legionella spp.), with important differences in the prevalence of these pathogens within the region. Antibiotic resistance was significant but was not linked to excess mortality. Aetiological pathogens remained susceptible to newer antimicrobial agents. Rational antibiotic use is essential for preventing resistance, and increased surveillance is required to identify future trends in incidence and aetiology and to drive treatment and prevention strategies.

Summary of invasive pneumococcal disease burden among children in the Asia-Pacific region

Invasive pneumococcal disease (IPD) burden is significant in the Asia-Pacific region. This review describes the epidemiology and Streptococcus pneumoniae (SP) serotype distribution of IPD in children in the Asia-Pacific region from studies published from 1999 to 2010. IPD incidence varies widely in Asia-Pacific countries depending on the method of surveillance, the population studied, and the time period. Incidences are highest for younger children, with rates near 100-200 cases per 100,000 children aged <1 or 2 years. Incidences of preventable disease are estimated to be 6-200 cases per 100,000. Heptavalent pneumococcal conjugate vaccine (PCV7) serotype coverage shows a very wide range over the Asia-Pacific region. Ten countries have high vaccine serotype coverage (>70%), and six countries have low vaccine serotype coverage (<50%). The majority of SP serotypes in children with IPD in most countries in the Asia-Pacific region are susceptible to penicillin (intermediate and resistant <50%); a few countries have SP serotypes with high level resistance to penicillin (intermediate and resistant >50%). Japan, Taiwan, and Thailand have high PCV7 serotype coverage. Countries with low pneumococcal resistance to antimicrobials have shown increasingly higher nonsusceptibility with time. National vaccination programmes that include PCV7, 10-valent pneumococcal conjugate vaccine (PCV), or 13-valent PCV would significantly affect IPD burden in children aged <5 years in the Asia-Pacific region, as well as the burden of penicillin-nonsusceptible IPD.

Impact of pneumococcal vaccines on invasive pneumococcal disease in Taiwan

In Taiwan, the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 7-valent pneumococcal conjugate vaccine (PCV7) have been available since January 2001 and October 2005, respectively. A hospital-based surveillance of invasive pneumococcal disease (IPD) in a medical center was conducted from 2000 to 2008 to evaluate the epidemiologic changes after pneumococcal vaccination. A total of 337 episodes in 328 patients were identified. The cumulative coverage rate of PPV23 among persons of age >or=75 years increased from 12% in 2007 to 41% in 2008, and that of PCV7 among children aged <5 years was 0.7% in 2005 and 25.2% in 2008. The annual incidence of IPD decreased from 6.2 cases per 10,000 hospitalizations in 2000-2005 to 3.8 cases in 2006-2008 (38.5% reduction, P < 0.001), but the fatality rate did not change significantly (24.4% and 21.8%, P = 0.74). The serotype coverage rates of PPV23 and PCV7 were not significantly different between 2000-2005 and 2006-2008 (both P > 0.05). A marked increase of serotype 19A from 2000-2005 (0.5%) to 2006-2008 (11.5%) was found (P < 0.001). In summary, a decline in IPD incidence but not in fatality rate occurred after the availability of PCV7 and the increased usage of PPV23. The rapid emergence of serotype 19A during this period is alarming.

Genome-wide dissection of globally emergent multi-drug resistant serotype 19A Streptococcus pneumoniae

BACKGROUND

Emergence of multi-drug resistant (MDR) serotype 19A Streptococcus pneumoniae (SPN) is well-documented but causal factors remain unclear. Canadian SPN isolates (1993-2008, n = 11,083) were serotyped and in vitro susceptibility tested. A subset of MDR 19A were multi-locus sequence typed (MLST) and representative isolates' whole genomes sequenced.

RESULTS

MDR 19A increased in the post-PCV7 era while 19F, 6B, and 23F concurrently declined. MLST of MDR 19A (n = 97) revealed that sequence type (ST) 320 predominated. ST320 was unique amongst MDR 19A in that its minimum inhibitory concentration (MIC) values for penicillin, amoxicillin, ceftriaxone, and erythromycin were higher than for other ST present amongst post-PCV7 MDR 19A. DNA sequencing revealed that alleles at key drug resistance loci pbp2a, pbp2x, pbp2b, ermB, mefA/E, and tetM were conserved between pre-PCV7 ST 320 19F and post-PCV7 ST 320 19A most likely due to a capsule switch recombination event. A genome wide comparison of MDR 19A ST320 with MDR 19F ST320 identified 822 unique SNPs in 19A, 61 of which were present in antimicrobial resistance genes and 100 in virulence factors.

CONCLUSIONS

Our results suggest a complex genetic picture where high-level drug resistance, vaccine selection pressure, and SPN mutational events have created a "perfect storm" for the emergence of MDR 19A.

Characterization of invasive isolates of Streptococcus pneumoniae among Taiwanese children

Accurate molecular surveillance is important in monitoring the dynamics of Streptococcus pneumoniae. A prospective study was conducted to collect invasive isolates of S. pneumoniae from children for genetic analysis from January 2004 to December 2006 in Taiwan. PCRs were performed to detect the zmpC and zmpD genes, both encoding a metalloprotease virulence factor in pneumococci, among these invasive isolates. During the study period, 68 invasive isolates of S. pneumoniae were obtained for analysis. Serotype 14 was the most common type isolated from children with invasive disease and was significantly associated with pneumonia (OR 3.1; 95% CI] 1.1-8.8; p 0.035). Serotype 23F was significantly associated with bacteraemia (OR 7.5; 95% CI 1.8-31.3; p 0.006). The seven-valent conjugate vaccine covered 83.8% of invasive isolates, but non-vaccine serotypes were more frequently isolated from patients with underlying diseases than from patients without underlying diseases (p 0.007 by Fisher's exact test). Clonal complexes related to international clones Spain23F ST81, Spain6B ST95, England14 ST9, Taiwan19F ST236, Taiwan23F ST242 and Colombia23F ST338 accounted for 52.9% of invasive isolates. Dissemination of the penicillin-resistant clones ST876, ST46, ST76 and ST2889, which were first identified in Taiwan, was also found; 1.5% of these invasive isolates carried the zmpC gene, and 47.1% of these invasive isolates carried the zmpD gene. In conclusion, the spread of certain international clones and some domestic antibiotic-resistant clones resulted in invasive diseases among Taiwanese children.