Changes in pneumococcal serotypes distribution and penicillin resistance in healthy children five years after generalization of PCV10

Objective

Streptococcus pneumoniae (S. pneumoniae) nasopharyngeal carriage has significantly decreased after the generalization of pneumococcal vaccination worldwide. This study sought to investigate changes in S. pneumoniae carriage rates, serotype distribution and penicillin non-susceptibility following the generalization of 10-valent pneumococcal conjugate vaccine.

Methods

A prospective study was conducted in Marrakesh, Morocco, between 2017 and 2018, among healthy children attending vaccination centers. We collected nasopharyngeal swabs and questionnaire data for each child. Using univariate logistic regression, we analyzed the association between S. pneumoniae carriage and various risk factors. Comparisons of serotype diversity and penicillin resistance between 2017 and 2018 and the period before introduction of vaccination (2008-2009, n = 660) were performed using Simpson index and the chi-squared test, respectively.

Results

During 2017-2018, 515 children aged between 6 and 36 months participated. The S. pneumoniae carriage rate was 43.3%. Looking at the distribution serotypes, the rate of PCV10 serotypes rate was only 9.6%. Among non-vaccine serotypes, an increase in serotypes 6C/6D (22; 14%), 19B/19C (17; 10.8%), and 15B/15C (11; 7%) was observed. A particular increase in serotype diversity was also observed after the generalization of PCV10 (p < 0.001). S. pneumoniae non-susceptible to penicillin decreased, reaching a rate of 26.6% in 2017-2018.

Conclusion

The significant change in S. pneumoniae carriage, serotype distribution, and penicillin resistance highlights the effectiveness of the pneumococcal conjugate vaccine among children in Marrakesh, Morocco.

Clinical and molecular characterization of the first culture-confirmed pediatric fulminant meningococcemia case caused by a serogroup Y clonal complex 23 strain in China

Serogroup Y Neisseria meningitidis (NmY) is rare in China, and only serogroup A and C meningococcal polysaccharide vaccines (MPVs) are included in the national vaccination schedule. We describe a case of fulminant meningococcemia caused by NmY, which occurred in a pediatric patient (2 years old) for the first time in China, confirmed by culture. Although the boy was treated in time, the dry gangrene in his toes and fingers left him with severe sequelae. An NmY isolate was cultured from the blood of the patient, and showed decreased susceptibility to penicillin (minimum inhibitory concentration of 0.125 μg/ml), with sequence type (ST) 1655 assigned to clonal complex (cc) 23. Genomic analysis showed it was clustered with isolates from Italy, UK, Finland, and South Africa, sharing designation of Y:P1.5-1,10-1:F4-1:ST-1655(cc23). The emergence of NmY invasive meningococcal disease cases challenges local immunization strategy and warrants wider usage of MPV-ACYW if there is sustained circulation of NmY.

What we actually know about the pathogenicity of Bacteroides pyogenes

The aim of the study was to evaluate the pathogenic potential of Bacteroides pyogenes, rarely identified in clinical laboratories anaerobic bacteria. To increase the knowledge about this poorly understood anaerobic microorganism, the study also includes cases of infections described so far in the literature. Only the use of 16S rRNA sequencing and mass spectrometry technique allowed the identification of B. pyogenes from clinical specimens. We reported 13 severe human infections caused by B. pyogenes. Bacteria were cultured from the wound after biting by animals, chronic infections within the oral cavity, from patients with histologically or radiological proven osteomyelitis, surgical site infection, and from urine sample collected after a urological procedure. Most (9/13) of the patients required hospitalization. Almost 70% of them needed urgent admission via the emergency room. Two inpatients due to a life-threatening condition were admitted to the intensive care unit. Almost 50% of isolates were resistant to penicillin. All resistant to penicillin strains were isolated from skin and mucous membrane infections.

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.

Increase in penicillin-resistant invasive meningococcal serogroup W ST-11 complex isolates in England

INTRODUCTION

Invasive meningococcal disease (IMD) caused by serogroup W meningococci belonging to the ST-11 complex (MenW:cc11) has been increasing globally since the early 2000s. Penicillin resistance among meningococci due to the production of beta-lactamase remains relatively rare. Isolates displaying resistance and reduced susceptibility to penicillin due to alterations in the penA gene (encoding Penicillin Binding Protein 2) are increasingly reported. In 2016, a penicillin-resistant clade of MenW:cc11 isolates with altered penA genes was identified in Australia. More recently, an increase in penicillin-resistant invasive MenW:cc11 isolates was observed in England. Here, we investigate the distribution of penicillin resistance among English invasive MenW:cc11 isolates.

METHODS

Isolates from IMD cases in England from July 2010 to August 2019 underwent whole genome sequencing and antibiotic susceptibility testing as part of routine surveillance. The PubMLST Neisseria database was used to determine the distribution of penicillin resistance among English MenW:cc11 isolates and to identify other closely related isolates.

RESULTS

Twenty-five out of 897 English invasive MenW:cc11 isolates were resistant to penicillin; identified among six distinct sublineages and a singleton. Expansion of the Australian penicillin-resistant clade included isolates from several new countries as well as 20 English isolates. A newly identified penicillin resistance-associated lineage was also identified among several countries.

CONCLUSION

Penicillin resistance among diverse MenW:cc11 isolates is increasing. Surveillance of antibiotic resistance among meningococci is essential to ensure continued effective use.

Analysis of amino acid motif of penicillin-binding proteins 1a, 2b, and 2x in invasive Streptococcus pneumoniae nonsusceptible to penicillin isolated from pediatric patients in Casablanca, Morocco

OBJECTIVES

This study aimed to investigate the nature of the amino acid motifs found in PBPs of Streptococcus pneumoniae isolates in invasive diseases from pediatric patients at Casablanca, Morocco. Five penicillin-susceptible (PSSP), ten penicillin-intermediate (PISP), and fifteen penicillin-resistant S. pneumoniae (PRSP) were studied by PCR-RFLP and DNA sequencing of the pbp1a, - 2b, and - 2x genes.

RESULTS

There were no changes in the conserved motifs of PBP1a, PBP2b and PBP2x for PSSP strains. Substitution close to PBP1a conserved motifs were found in all PRSP isolates and six/five PISP. Analysis of PBP2b showed that all but one of the 10 PISP strains and all PRSP had substitutions. Substitution close to PBP2x motifs showed that all but three of the 10 PISP strains and all PRSP had substitutions in tow conserved motifs. A total of 6, 11 and 10 genotypes were found after analysis of pbp1a, pbp2b, and pbp2x, respectively. The penicillin-nonsusceptible S. pneumoniae isolated in Casablanca share most amino acid substitutions of those reported worldwide, but they occurred among pneumococci with low level resistance to b-lactams.

Invasive pneumococcal disease in Indian adults: 11 years' experience

PURPOSE

To investigate the epidemiology of invasive pneumococcal disease (IPD), prevalent serotypes, and pattern of antimicrobial resistance (AMR) in Indian adults.

METHODS

Prospective laboratory based surveillance of IPD was carried out in >18 years age group between January 2007 and July 2017, from a tertiary care hospital in South India. All Streptococcus pneumoniae culture positives from blood, CSF and sterile body fluids were characterized to identify the serotypes and AMR.

RESULTS

A total of 408 IPD cases were characterized in this study. The overall case fatality rate in this study was 17.8% (95% confidence interval (CI): 14.1, 22.4). Pneumonia (39%), meningitis (24.3%), and septicaemia (18.4%) were the most common clinical conditions associated with IPD. Serotypes 1, 3, 5, 19F, 8, 14, 23F, 4, 19A and 6B were the predominant serotypes in this study. Penicillin non-susceptibility was low with 6.4% CONCLUSION: Serotype data from this study helped in accurate estimation of pneumococcal conjugate vaccine-13 and pneumococcal polysaccharide vaccine-23 protective coverage against serotypes causing IPD in India as 58.7% (95% CI: 53.8, 63.4) and 67.4% (95% CI: 62.7, 71.8) respectively. Penicillin non-susceptibility in meningeal IPD cases is 27.4%. Empirical therapy for meningeal IPD must be cephalosporin in combination with vancomycin since cefotaxime non-susceptibility in meningeal IPD is 9.9.

Increased rate of penicillin non-susceptible strains of N. meningitidis in Naples, Italy

Neisseria meningitidis is a causative agent of community-acquired sepsis and meningitis in humans. These diseases are associated with high mortality and morbidity if treatment is not started promptly. The empiric antibiotic treatment depends on patient factors and local epidemiology. In the past years, an increased number meningococcal strain with reduced susceptibility to penicillin has also been described. We analysed the susceptibility pattern of 11 N. meningitidis strains isolated between 2013 and 2016. Only three (27%) strains were fully susceptible to penicillin, suggesting that a third-generation cephalosporin, instead of penicillin, as empiric therapy is more reliable when an invasive meningococcal disease is suspected.

Natural transformation and genome evolution in Streptococcus pneumoniae

Streptococcus pneumoniae is a frequent colonizer of the human nasopharynx that has the potential to cause severe infections such as pneumonia, bacteremia and meningitis. Despite considerable efforts to reduce the burden of pneumococcal disease, it continues to be a major public health problem. After the Second World War, antimicrobial therapy was introduced to fight pneumococcal infections, followed by the first effective vaccines more than half a century later. These clinical interventions generated a selection pressure that drove the evolution of vaccine-escape mutants and strains that were highly resistant against antibiotics. The remarkable ability of S. pneumoniae to acquire drug resistance and evade vaccine pressure is due to its recombination-mediated genetic plasticity. S. pneumoniae is competent for natural genetic transformation, a property that enables the pneumococcus to acquire new traits by taking up naked DNA from the environment and incorporating it into its genome through homologous recombination. In the present paper, we review current knowledge on pneumococcal transformation, and discuss how the pneumococcus uses this mechanism to adapt and survive under adverse and fluctuating conditions.

[Ceftaroline fosamil in community-acquired and nosocomial pneumonia]

Community-acquired pneumonia (CAP) is a common infection in developed countries and causes a large number of hospital admissions and deaths. In recent years, the incidence of this disease has increased, caused by progressive population aging. Following the introduction of the conjugate vaccine against Streptococcus pneumoniae, there have been significant epidemiological changes that require close monitoring because of the possible emergence of new patterns of resistance. This article aims to review the role of ceftaroline fosamil, a new parenteral cephalosporin with antibacterial activity against Gram-negative and Gram-positive pathogens, in the treatment of pneumonia. Several in vitro and in vivo studies have shown the efficacy of ceftaroline fosamil against penicillin-resistant S. pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA). Additionally, ceftaroline has shown similar efficacy and safety to ceftriaxone in the treatment of community-acquired pneumonia with severe prognosis (prognostic severity index III and IV) in two phase III clinical trials. Although a non-inferiority design was used for these clinical trials, some data suggest a superior efficacy of ceftaroline, with earlier clinical response and higher cure rate in infections caused by S. pneumoniae, making this drug particularly interesting for critically-ill patients admitted to the intensive care unit. Ceftaroline may also be considered for empirical and directed treatment of MRSA pneumonia.

Penicillin susceptibility and macrolide-lincosamide-streptogramin B resistance in group B Streptococcus isolates from a Canadian hospital

BACKGROUND

Intrapartum antibiotic prophylaxis (IAP) is recommended for pregnant women who test positive for group B Streptococcus (GBS) in their genitourinary tract to prevent GBS-induced neonatal sepsis. Penicillin G is used as the primary antibiotic, and clindamycin or erythromycin as the secondary, if allergies exist. Decreased susceptibility to penicillin G has occasionally been reported; however, clindamycin and erythromycin resistance is on the rise and is causing concern over the use of clindamycin and erythromycin IAP.

METHODS

Antibiotic resistance was characterized phenotypically using a D-Test for erythromycin and clindamycin, while an E-Test (E-strip) was used for penicillin G. GBS was isolated from vaginal-rectal swabs and serologically confirmed using Prolex (Pro-Lab Diagnostics, Canada) streptococcal grouping reagents. Susceptibility testing of isolates was performed according to the Clinical Laboratory Standards Institute guidelines.

RESULTS

All 158 isolates were penicillin G sensitive. Inducible macrolide-lincosamide-streptogramin B (MLSB) resistance was observed in 13.9% of isolates. Constitutive MLSB resistance was observed in 12.7% of isolates. M phenotype resistance was observed in 6.3% of isolates. In total, erythromycin resistance was present in 32.9% of the GBS isolates, while clindamycin resistance was present in 26.6%.

DISCUSSION

The sampled GBS population showed no sign of reduced penicillin susceptibility, with all being well under susceptible minimum inhibitory concentration values. These data are congruent with the large body of evidence showing that penicillin G remains the most reliable clinical antibiotic for IAP. Clindamycin and erythromycin resistance was higher than expected, contributing to a growing body of evidence that suggests the re-evaluation of clindamycin and erythromycin IAP is warranted.

Reduced susceptibility to penicillin among pneumococci causing invasive infection in children - Canada, 1991 to 1998

OBJECTIVE

To determine, over time, the rate and serotypes of pneumococci with reduced penicillin susceptibility obtained from children with invasive infection.

DESIGN

Active, hospital-based, multicentre surveillance spanning from 1991 to 1998.

SETTING

Eleven Canadian tertiary care paediatric facilities located from coast to coast.

POPULATION STUDIED

1847 children with invasive pneumococcal infection whose isolates (from a normally sterile site) were available for serotyping and standardized testing for penicillin susceptibility at the National Centre for Streptococcus.

MAIN RESULTS

The prevalence of reduced penicillin susceptibility increased from 2.5% of 197 cases in 1991 to 13.0% of 276 cases in 1998. In the latter year, 8.7% of isolates had intermediate level resistance, and 4.3% had high level resistance. Since they were first detected in 1992, strains with high level resistance have been encountered only sporadically at most centres, but by 1998, all centres but two had encountered examples. Of 40 isolates with high level resistance and 101 isolates with intermediate level resistance, serotypes matched those included in new seven-valent conjugate vaccines for children in 97.5% and 79.2% of cases, respectively.

CONCLUSIONS

Pneumococci with reduced susceptibility to penicillin are increasing in frequency across Canada among children with invasive infection. The Immunization Monitoring Program, Active data indicate that new conjugate vaccines could help to curb infections due to pneumococci with reduced susceptibility to penicillin but are unlikely to control completely the problem of antibiotic resistance.

Nasopharyngeal Carriage, Antibiotic Resistance and Serotype Distribution of Streptococcus Pneumoniae among Healthy Adolescents in Zahedan

BACKGROUND

Colonization of nasopharynx by Streptococcus pneumoniae can lead to pneumococcal diseases. This study was performed to determine the carriage rate of nasopharyngeal S. pneumoniae in adolescents, antibiotic susceptibility and serotype prevalence in Zahedan, Iran.

METHODS

Nasopharyngeal specimens from 865 adolescents (age range: 10-19 years old) attending eight schools in Zahedan, Iran, were collected and assessed by standard procedures to recover S. pneumoniae. The serotyping was carried out by latex agglutination test and the minimum inhibitory concentrations (MIC) of penicillin as well as other commonly used antibiotics were determined by a broth dilution method.

RESULTS

Pneumococci were recovered from 15.7% (136/865, 95% confidence interval (CI) 12.3-18.9) of total samples which 119 isolates were typable with the available antisera. 1, 19A, 15C, 9V, 11A and 19F were found as the most frequent serotypes. Ninety three pneumococcal isolates were sensitive to penicillin. The MIC values of antibiotics tested were (μg/ml): penicillin 0.01-4, cefotaxime 0.01-4, ceftriaxone 0.02-128, chloramphenicol 0.08-32, ciprofloxacin 0.06-16, erythromycin 0.01-128, tetracycline 0.08-128 and vancomycin 0.02-1.

CONCLUSION

A clear diversity was seen in the serotype distribution of the S. pneumoniae isolates and most of the antibiotic resistant strains belonged to few serotypes. Healthy adolescents in Zahedan, Iran commonly show pneumococcal carriage and antibiotic resistance.