Protective eff ect and mechanism of nanoantimicrobial peptide ND-C14 against Streptococcus pneumoniae infection

BACKGROUND:Streptococcus pneumoniae(S.pneumoniae)is a common pathogen that causes bacterial pneumonia.However,with increasing bacterial resistance,there is an urgent need to develop new drugs to treat S.pneumoniae infections.Nanodefensin with a 14-carbon saturated fatty acid(ND-C14)is a novel nanoantimicrobial peptide designed by modifying myristic acid at the C-terminus of humanα-defensin 5(HD5)via an amide bond.However,it is unclear whether ND-C14 is effective against lung infections caused by S.pneumoniae.METHODS:In vitro,three groups were established,including the control group,and the HD5 and ND-C14 treatment groups.A virtual colony-count assay was used to evaluate the antibacterial activity of HD5 and ND-C14 against S.pneumoniae.The morphological changes of S.pneumoniae treated with HD5 or ND-C14 were observed by scanning electron microscopy.In vivo,mice were divided into sham,vehicle,and ND-C14 treatment groups.Mice in the sham group were treated with 25μL of phosphate-buffered saline(PBS).Mice in the vehicle and ND-C14 treatment groups were treated with intratracheal instillation of 25μL of bacterial suspension with 2×108 CFU/mL(total bacterial count:5×10^(6) CFU),and then the mice were given 25μL PBS or intratracheally injected with 25μL of ND-C14(including 20μg or 50μg),respectively.Survival rates were evaluated in the vehicle and ND-C14 treatment groups.Bacterial burden in the blood and bronchoalveolar lavage fluid were counted.The lung histology of the mice was assessed.A propidium iodide uptake assay was used to clarify the destructive eff ect of ND-C14 against S.pneumoniae.RESULTS:Compared with HD5,ND-C14 had a better bactericidal eff ect against S.pneumoniae because of its stronger ability to destroy the membrane structure of S.pneumoniae in vitro.In vivo,ND-C14 significantly delayed the death time and improved the survival rate of mice infected with S.pneumoniae.ND-C14 reduced bacterial burden and lung tissue injury.Moreover,ND-C14 had a membrane permeation eff ect on S.pneumoniae,and its destructive ability increased with increasing ND-C14 concentration.CONCLUSION:The ND-C14 may improve bactericidal eff ects on S.pneumoniae both in vitro and in vivo.

Acute coalescent mastoiditis in a 16-month-old child due to Streptococcus pneumoniae infection

Rationale:Acute otitis media is a common disease in early childhood,and is usually caused by Streptococcus pneumoniae(S.pneumoniae).Acute mastoiditis is a complication of acute otitis media and can involve not only the mucoperiosteum of the middle ear but can also spread to the periosteum by destroying the mastoid bone(acute coalescent mastoiditis).In addition,the infection can extend through the surrounding bones or the emissary veins beyond the mastoid’s air cells,leading to subperiosteal abscesses.Patient’s Concern:A 16-month-old female patient was hospitalized due to the purulent discharge of the left ear and the symptoms of right mastoiditis(swelling and redness of the skin).Diagnosis:Bilateral acute coalescent mastoiditis caused by S.pneumoniae infection.The computer tomography revealed bilateral bone destruction of the mastoid and abscesses found behind the auricle on both sides.Interventions:The patient underwent intravenous antibiotic therapy and surgical treatment.Outcomes:The patient was discharged 14 days after hospitalization with an improved condition.Lessons:Improperly treated acute coalescent mastoiditis can lead to extracranial and intracranial complications,sometimes serious and even life-threatening.Complications are prevalent in children under 2 years,in whom the disease progresses more rapidly and severely.The vaccination with a 13-valent vaccine may not result in sufficient immunity against S.pneumoniae,a predominant pathogen in children affected by acute coalescent mastoiditis.

Antibiotic Resistance Profile of Serotypes of Streptococcus pneumoniae Strains in Bangui, from 2017 to 2022: Case of Serotype 1

Goals: The aim of this study was to determine the antibiotic resistance profile of serotypes of Streptococcus pneumoniae strains circulating in Bangui. Methodology: A prospective and analytical analysis was carried out at the National Laboratory of Clinical Biology and Public Health from 2017 to 2022. The strains came from our study on the contribution to the study of antibiotic sensitivity of Streptococcus pneumoniae strains. The multiplex PCR test was used for its cost-effectiveness in terms of amplifiers which can be purified in order to be sequenced. It also makes it possible to detect several germs as well as their serotypes. For a PCR reaction, several elements are involved in the reaction medium or Master Mix. These are the desoxyribonucleotides (dNTPs), the magnesium ions (MgCl2) and the primers. A set of 14 primers divided into 3 classes were used. Class 1 primers served as an internal control by targeting the cpsA gene. It is a highly conserved gene found in capsular loci characterized to date. The primers of the second class were used to target specific serotypes by specific reactions (out of six possibilities). The group reaction was carried out using the primers of the third class in order to carry out an initial screening of the samples and to classify the pneumococcal isolates. Related serotypes were grouped based on the amplification of common genes. Using the technique of electrophoresis on agarose gel and an ultraviolet radiation device, the migration bands are then visualized and analyzed. The data collected had been entered into Excel 2010 and analyzed with Epi info 7. The exact Fischer chi2 test at the 5% threshold, the relative risk and its 95% confidence interval were used to compare the proportions and determine the associations. Results: 187 antibiotic-resistant strains of Streptococcus pneumoniae were collected. The average frequency of serotypes 1, 9A, 4 and untypeable identified were 43.59%, 18.18%, 18.27% and 39.57% respectively. The frequency of serotype 1 was predominant for the age group over five years old with 56.88%. The male sex was predominant with 55.08% for serotype 1. Resistance to penicillin and gentamicin for serotype 1 during this study, for the age group under 5 years old, was 77%. For serotypes 19A and 4, tetracycline resistance was predominant with 20% for the age group under 5 years. The resistance to penicillin and gentamicin of non-typeable serotypes was 33% for the age group under 5 years old. For the age group over 5 years old, resistance to erythromycin predominated at 37%. The distribution of serotypes by sex depending on antibiotic resistance was variable. There was a statistically significant association between identified serotypes and antibiotic resistance (p Conclusion: The study determined serotypes 1, serotypes 19A, serotypes 4 and non-typeable serotypes. These results would be due to the quality of vaccination or poor protection of vaccines.

ST of Streptococcus pneumonia Circulating in Burkina Faso before the Introduction of PCV-13, 2013

Introduction: Burkina Faso experiences regular cases of Streptococcus pneumoniae meningitis. As part of the strategy to reduce cases of meningitis, the 13-valent pneumococcal conjugate vaccine (PCV-13) has been introduced in the Expanded Programme on Immunisation (EPI). Despite these efforts, there are some cases of pneumococcal meningitis including both vaccine and non-vaccine serotypes. The objective of this study was to describe the pneumococcal sequence types (ST) circulating in Burkina Faso before the introduction of the 13-valent pneumococcal conjugate vaccine (PCV-13). Methods: It was a descriptive cross-sectional study that took place from 27th October 2013 to 7th January 2014. S. pneumoniae strains were collected in Burkina Faso and Multi Locus Sequence Typing (MLST) was performed at the Pneumococcal Laboratory at the Centers for Disease Control and Prevention (CDC) in the USA (United States of America). MLST consists of 4 steps: amplification, purification, sequencing and interpretative reading of the results. The amplification used 7 primers consisting of sequences of aroe, gdh, gki, recP, spi, xpt, ddl genes. Results: Of 37 strains tested, 10 serotypes were identified. Serotype 1 was prevalent in 48.7% (18/37) followed by serotype 25F in 10.8% (4/37). Serotypes 5 and 12F/12A/12B/44/46 were 8.1% (3/37) each. Serotype 1 contained 5 STs including ST303 24.3% (9/37), ST217 8.1% (3/37) and ST618 8.1% (3/37);followed by serotype 25F with ST105 10.8% (4/37), serotype 5 with ST289 8.1% (3/37) and serogroup 12F/12A/12B/44/46 with ST 989 8.1% (3/37). Conclusion: Pneumococci are characterised by their great variability both in number of serotypes and in ST within the same serotype. Thus, 10 serotypes have been identified. Also, within serotype 1, 5 different STs have been described. These data indicate the complexity of the pneumococcus which is strongly involved in purulent bacterial meningitis at national level. This requires continuous surveillance of pneumococcal meningitis through laboratory capacity building.

Streptococcus pneumoniae and Herpes Simplex Virus-1 Central Nervous System Co-Infection

Co-infections of the central nervous system (CNS) caused by bacterial and viral pathogens are considered to be rare. Herpes simplex virus type-1 (HSV-1) reactivation following Streptococcus pneumoniae infection is well described but most cases are related to oral or cutaneous lesions or in respiratory samples. HSV-1 CNS reactivation after Streptococcus pneumoniae meningitis is a very rare event and may have significant morbidity and mortality. In this case report, we describe a 71-year-old female patient that presented with a history of abdominal pain and confusion/disorientation that had tonic-clonic seizures while in the Emergency Department. The diagnostic work-up confirmed CNS co-infection caused by Streptococcus pneumoniae and HSV-1. Of note, beyond age, the patient had no known risk factors for both entities and recovered fully after antibiotic and antiviral therapy. This case underlines that clinicians must be aware of CNS co-infection despite being a rare diagnosis. This should be suspected particularly in patients who present an unusual clinical course of CNS infection.

Contribution to the Study of Antibiotic Sensitivity of Streptococcus pneumoniae Strains in Spinal Cerebral Fluids in Bangui from 2017 to 2022

A prospective and analytical study was carried out from January 2017 to Decem-ber 2022, at the National Laboratory of Clinical Biology and Public Health (LNBCSP) in Bangui. 352 samples of cerebrospinal fluid (CSF) were confirmed out of 2065, coming from the four hospitals in Bangui. This study aimed to evalu-ate the evolution of antibiotic sensitivity to strains of Streptococcus pneumoniae. CSF had been collected from patients who presented with meningeal syndromes. Based on the leukocyte count (White blood cells ≥ 5 mm3), an aliquot was trans-ferred to trans-isolate medium and sent to the LNBCSP for confirmatory testing, culture and determination of antibiotic sensitivity. The antibiotic sensitivity of Streptococcus pneumoniae strains was tested according to the methods recom-mended by the Antibiogram Committee of the French Society of Microbiology. The data collected was entered into Excel 2010 to be analyzed with Epi Info 7.2. Ficher’s exact test, chi2 at the 5% threshold (p < 0.05) was used to compare pro-portions and analyze associations between variables. The average sensitivity rate to β-lactams was 74.43%. The sensitivity rate of Fluoroquinolones was 54.54%. That of levofloxacin was 87%. The average rate of sensitivity to β-lactams for the age group under 5 years old was 79.25%. That of fluoroquinolones was 52.59%. Levofloxacin had 90.37%. The average sensitivity rate to β-lactams for the age group over 5 years old was 76.03%. Fluoroquinolones had 45.16%. Levofloxacin had 69.58%. The average sensitivity rate to β-lactams for males was 76.68%. Fluoroquinolones had 54.26%. That of levofloxacin was 83.40%. The sensitivity rate to β-lactams for females was 74.41%. That of fluoroquinolones was 51.16%. Levofloxacin had 67.44%. Cyclins had 28.68%. The study noted an association between age and sensitivity (p < 0.05;CI [1.05-2.57]). Strains of Streptococcus pneumoniae were always detected in the CSF. The average rate of sensitivity to macrolides was 36.93%;aminoglycosides 28.69%;phenicols 63.35%;sulfona-mides 39.2%. These results could suggest a reduced sensitivity to β lactams. .

A Cross-sectional Survey Assessing Carriage of Streptococcus pneumoniae in a Healthy Population in Xinjiang Uygur Autonomous Region of China

The carriage rate and serotype distribution of Streptococcus pneumoniae（S.pneumoniae）in a healthy population in China remains unclear.In this study,we collected the oropharyngeal swabs from513 individuals in Xinjiang,China.Real-time PCR targeting the lytA gene and 12 serotypes were assessed to identify S.pneumoniae carriage.

Molecular Characterization and Correlation with β-lactam Resistance of Streptococcus pneumonia Isolates in Hangzhou,China

Penicillin-binding proteins（PBPs） are the target of β-lactam antibiotics（the major treatment for Streptococcus pneumoniae infections）,and mutations in PBPs are considered as a primary mechanism for the development of β-lactam resistance in S.pneumoniae.This study was conducted to investigate the mutations in the PBPs of clinical S.pneumoniae isolates in Hangzhou,China,in correlation with β-lactam resistance.Results showed that 19 F was the predominant serotype（7/27） and 14 of the S.pneumoniae isolates were resistant to both penicillin G and cephalosporin.Genotyping results suggested that β-lactam-resistant isolates primarily exhibited single-site mutations in both the STMK and SRNVP motifs of pbp1 a in combination with double-site mutations in the STMK motif of pbp2 x,which might be the primary mechanisms underlying the β-lactam resistance of the isolates in this study.

Expression,Purification,Characteristics and Homology Modeling of the HMGS from Streptococcus pneumoniae

Objective To understand the molecular basis for a potential reaction mechanism and develop novel antibiotics with homology modeling for 3-hydroxy-3-methylglutaryl coenzyme A （HMG-CoA） synthase （HMGS）. Methods The genetic engineering technology and the composer module of SYBYL7.0 program were used, while the HMGS three-dimensional structure was analyzed by homology modeling. Results The mvaS gene was cloned from Streptococcus pneumoniae and overexpressed in Escherichia coli from a pET28 vector. The expressed enzyme （about 46 kDa） was purified by affinity chromatography with a specific activity of 3.24 μmol/min/mg. Optimal conditions were pH 9.75 and 10 mmol/L MgCl2 at 37 ℃ The Vmax and Km were 4.69 μmol/min/mg and 213 μmol/L respectively. The 3D model of S.pneumoniae HMGS was established based on structure template of HMGS of Enterococcus faecalis. Conelusion The structure of HMGS will facilitate the structure-based design of alternative drugs to cholesterol-lowering therapies or to novel antibiotics to the Gram-positive cocci, whereas the recombinant HMGS will prove useful for drug development against a different enzyme in the mevalonate pathway.

Children with Pneumonia Caused by Streptococcus pneumoniae Resistance Analysis and Clinical Features

Objective: To analyze the causes of childhood pneumonia Streptococcus pneumoniae resistance and clinical characteristics, and provide a basis for better and timely clinical therapy, and medication to reduce blind-ness. Methods: MIC method in our hospital 114 under 2020 pediatric pneumococcal respiratory infection in children with lower respiratory tract specimens were isolated antimicrobial susceptibility testing, and analyzed retrospectively. Results: 84 male children, 30 female children, the largest of which 9 years old, the youngest two months, infants less than 1 year old, 90 people;suffering from bronchial pneumonia, 90 cases, 21 cases of pneumonia, wheezing, 3 cases of bronchitis, the average length of stay for about a week;improved in 79 cases, 33 cases were cured, 2 cases transferred to higher level hospitals. All children with throat congestion, swollen tonsils, lung breath sounds rough, smell and moist rales. 114 penicillin-resistant Streptococcus pneumoniae was 64.9%, erythromycin 97.4%, clindamycin 86.8%, tetracycline 87.7%, trimethoprim-sulfamethoxazole 82.5%, amoxicillin 21.9%, cefotaxime 49.1%, chloramphenicol 10.5%, was not found to levofloxacin and van-comycin. Conclusion: Penicillin, erythromycin, and clindamycin are not as pneumococcal pneumonia in children experience preferred medi-cation in children less than one year old child could easily cause lung chain Streptococcus pneumoniae. Therefore, the antimicrobial resistance of Streptococcus pneumoniae analysis provides a reference for experi-enced clinicians to adjust medication.

Antimicrobial susceptibility and serotypes of Neisseria meningitidis and Streptococcus pneumoniae in Sri Lanka:Experience from the National Reference Laboratory

Objective:To determine the antimicrobial susceptibility and serotypes of Neisseria(N.)meningitidis and Streptococcus(S.)pneumoniae in Sri Lankan patients.Methods:We retrospectively analyzed 11 blood culture specimens from suspected patients with invasive meningococcal disease and 26 S.pneumoniae clinical isolates.We tested 6 antimicrobials against N.meningitidis and 12 antimicrobials against S.pneumoniae.Meningococcal serogroup was determined by realtime PCR and Quellung serotyping was used for pneumococcal analysis.Results:N.meningitidis serogroup B was the most common in this study.Intermediate-susceptibility to penicillin was seen in 75.0%(6/8)of strains.Susceptibility to ciprofloxacin,levofloxacin and cotrimoxazole was 62.5%(5/8),62.5%(5/8)and 87.5%(7/8),respectively.Excellent susceptibility was seen in cefotaxime and meropenem.In S.pneumoniae,the most common serotype was 19F in both invasive and non-invasive pneumococcal diseases.The majority of strains showed multidrug resistance.Penicillin non-susceptibility in non-meningeal strains were 13.6%and all meningeal strains were penicillin resistant.Erythromycin was highly resistant in both groups.Amoxicillin showed excellent susceptibility in non-invasive pneumococcal diseases strains.Linezolid,levofloxacin and vancomycin showed 100.0%susceptibility in all pneumococcal isolates.Conclusions:Implementation of vaccines should be considered,especially for children and high-risk populations.This may contribute to reducing pneumococcal and meningococcal invasive disease burden and help prevent emergence of antimicrobial resistant strains.

Evolution of Erythromycin Resistance among Streptococcus pneumoniae Isolates in Malaysia from 2005 and 2010

Objectives: This study focuses on the antibiotic susceptibility pattern and distribution of the ermB and mefA virulence genes among the Streptococcus pneumoniae due to an increase in erythromycin resistance in S. pneumoniae worldwide. Methodology: We investigated 255 clinical isolates collected from 2005-2010 to determine the serotype distribution and resistance to erythromycin in comparison to penicillin, clindamycin, clarithromycin, azithromycin, and trimethoprim sulfamethoxazole. Multiplex PCR was carried out to detect erythromycin resistance genes (ermB and mefA). Results: There were 146 (57.3%) isolates resistant to erythromycin. MIC90 for erythromycin is at >256 mg/L and MIC50 is at 16 mg/L. The ermB gene was detected in 25.3% of the erythromycin-resistant isolates and mefA gene was detected in 50.7% of the isolates. The four most common serotypes encountered are 19F, 19A, 23F and 14. The serotype distribution among the erythromycin resistant isolates was 19F (42.0%) followed by serotype 19A (11.3%), serotype 23F (9.2%) and serogroup 14 (7.0%). Conclusion: In conclusion, there is a significant rise in erythromycin resistance among the Malaysian pneumococcal isolates. The emergence of serotype 19A together with increasing prevalence of resistance to macrolide warrants for a more extensive surveillance study.

Penicillin Resistance in Nasopharyngeal Streptococcus pneumoniae among Children with Sickle Cell Disease Immunized with 7-Valent Pneumococcal Conjugate Vaccine

To assess the prevalence, the antimicrobials resistance and to identify risk factors of nasopharyngeal colonization by Streptococcus pneumoniae in children with sickle cell disease (SCD) using prophylactic penicillin and immunized with 7-valent pneumococcal conjugate vaccine. A total of 424 swabs were collected from the nasopharynx in 216 children with SCD and 109 samples from the control group, both from 2 to 60 months age range. Isolation and identification of pneumococci followed standard procedures. Minimum inhibitory concentration (MIC) for penicillin was determined by the E-test method. Prevalence of nasopharyngeal colonization by pneumococci in children with SCD was 17%, and 11% in the control group. The risk factors for increased colonization in children with SCD were the presence of more than five people at home, daycare/school attendance and low prophylaxis compliance. The prevalence of strains with penicillin resistance was 57.5% in patients with SCD and 25% in the control group. Conclusions: Prevalence of pneumococci nasopharyngeal colonization was similar among the study groups. Prophylactic use of penicillin may have increased the prevalence of resistant strains. The vaccine did not decrease the colonization with penicillin resistant strains.

Development of protective antibodies to Streptococcus pneumoniae in healthy children

Aim: To study how immunity to Streptococcus pneumoniae normally develops in healthy children. Methods: Ninety two healthy children at 3 - 5, 7 - 9 and 13 - 15 years of age were recruited. No one of the children had previously been given pneumococcal vaccine. Serum was analysed for pooled antigens of the 23 most common pneumococcal polysaccharides with ELISA technique, and results are given in opitical density (OD). A three-level semi-quantitative system was used to assess degree of immunity to Streptococcus pneumoniae . Cut-off levels were OD ≤ 0.7 and OD ≥ 1.3, separating low, intermediate and high degree of immunity. Results: Median values for OD differed significantly between the groups, with OD 0.91, 1.18 and 1.10 respectively (p = 0.004). Levels were lower in the youngest age group, but from age 7-9 years, levels were similar trough out childhood. Twenty six percent of the children in the youngest age-group had a low degree of protection (OD ≤ 0.7) to Streptococcus pneumoniae . Such low levels were uncommon from 7 - 9 years of age, found in only 13% of the children. Conclusion: Protective antibodies to Streptococcus pneumoniae develops mainly during the preschool period. Thereafter, levels are stable throughout childhood up to the age of 15 years.

Streptococcal pneumonia-associated hemolytic uremic syndrome treated by T-antibody-negative plasma exchange in children: Two case reports

BACKGROUND The occurrence of Streptococcus pneumoniae-associated hemolytic uremic syndrome(SP-HUS)is increasing.Thomsen-Friedenreich antigen activation is highly involved in the pathogenesis of SP-HUS,and T-antibody-negative plasma exchange(PE)may be effective in the treatment of severe cases of SP-HUS.CASE SUMMARY We retrospectively reviewed two pediatric patients with SP-HUS.Both clinical features and laboratory examination results of the children were described.Tantibody-negative PE was performed in both cases.Both children made a full recovery after repeated PE and remained well at a 2 year follow-up.CONCLUSION Streptococcal pneumonia continues to be an uncommon but important cause of HUS.The successful treatment of the presented cases suggests that T-antibodynegative PE may benefit patients with SP-HUS.

Establishment and Modification of Ninety-seven Pneumococcal Serotyping Assays Based on Quantitative Real-time Polymerase Chain Reaction

Objective To establish and modify quantitative real-time polymerase chain reaction(qPCR)-based serotyping assays to distinguish 97 pneumococcal serotypes.Methods A database of capsular polysaccharide(cps)loci sequences was generated,covering 97 pneumococcal serotypes.Bioinformatics analyses were performed to identify the cps loci structure and target genes related to different pneumococcal serotypes with specific SNPs.A total of 27 novel qPCR serotyping assay primers and probes were established based on qPCR,while 27 recombinant plasmids containing serotype-specific DNA sequence fragments were constructed as reference target sequences to examine the specificity and sensitivity of the qPCR assay.A panel of pneumococcal reference strains was employed to evaluate the capability of pneumococcal serotyping.Results A total of 97 pneumococcal serotyping assays based on qPCR were established and modified,which included 64 serotypes previously reported as well as an additional 33 serotypes.Twenty-seven novel qPCR serotyping target sequences were implemented in the pneumococcal qPCR serotyping system.A total of 97 pneumococcal serotypes,which included 52 individual serotypes and 45 serotypes belonging to 20 serogroups,could not be identified as individual serotypes.The sensitivity of qPCR assays based on 27 target sequences was 1–100 copies/μL.The specificity of the qPCR assays was 100%,which were tested by a panel of 90 serotypes of the pneumococcal reference strains.Conclusion A total of 27 novel qPCR assays were established and modified to analyze 97pneumococcal serotypes.

Development of subdural empyema from subdural effusion after suppurative encephalitis:A case report

BACKGROUND Chronic subdural effusion is very common in the cranial imaging of middle-aged and older people.Herein,we report a patient misdiagnosed with subdural effusion,who was eventually diagnosed with chronic subdural empyema(SDE)caused by Streptococcus pneumoniae.CASE SUMMARY A 63-year-old man was brought to our emergency room with a headache,vomiting,and disturbed consciousness.Computed tomography(CT)revealed a bilateral subdural effusion at the top left side of the frontal lobe.Cerebrospinal fluid examination after lumbar puncture indicated suppurative meningitis,which improved after anti-infective therapy.However,the patient then presented with acute cognitive dysfunction and right limb paralysis.Repeat CT showed an increase in left frontoparietal subdural effusion,disappearance of the left lateral ventricle,and a shift of the midline to the right.Urgent burr hole drainage showed SDE that was culture-positive for Streptococcus pneumoniae.His condition improved after adequate drainage and antibiotic treatment.CONCLUSION Patients with unexplained subdural effusion,especially asymmetric subdural effusion with intracranial infection,should be assessed for chronic SDE.Early surgical treatment may be beneficial.

Nasal carriage of Streptococcus pneumoniae among children in Beijing

Objective To investigate the antimicrobial susceptibility of Streptococcus pneumoniae carried in the nose among children in Beijing and the distribution of serotypes,and to analyze the risk factors for nasal carriage of penicillin non-susceptible S.pneumoniae.Methods A disk diffusion test was applied to detect the antimicrobial susceptibilities of S.pneumoniae to erythromycin,trimethoprim-sulfamethoxazole,chloramphenicol and tetracycline.The E test was applied to determine the minimal inhibitory concentrations of penicillin,cefuroxime,cefotaxime,augmentin and imipenem.S.pneumoniae isolates were serotyped by the Quellung reaction.Results S.pneumoniae that was resistant to penicillin or cefuroxime was not found,but S.pneumoniae intermediate resistant to penicillin and cefuroxime accounted for 8.2% and 2.1%,respectively.All of the isolates were susceptible to cefotaxime,augmentin and imipenem.S.pneumonia that was resistant to erythromycin,trimethoprim-sulfamethoxazole and tetracycline were extremely numerous,accounting for 72%,70% and 79%,respectively.Five serotypes(19,6,14,23,17)accounted for 54.7%,and nontypables accounted for 20.6% of all the S.pneumoniae.Previous history of otitis media was a risk factor we found for nasal carriage of penicillin non-susceptible S.pneumoniae.Conclusions Continued surveillance of the antimicrobial susceptibilities of S.pneumoniae is necessary.A larger scale investigation is needed to identify if the 7 or 9-valent conjugate pneumococcal vaccine is appropriate for Chinese children.

Serological and molecular capsular typing, antibiotic susceptibility and multilocus sequence typing of Streptococcuspneumoniae isolates from invasive and non-invasive infections

Background Streptococcus pneumoniae （S.pneumoniae） is a major causative agent of severe infections,including sepsis,pneumonia,meningitis,and otitis media,and has become a major public health concern.We report the pneumococcal serotype and sequence type （ST） distribution,and antimicrobial resistance of 39 S.pneumoniae strains from seven hospitals in China.Methods Blood/cerebrospinal fluid （CSF） and sputum isolates from patients were analyzed to determine S.pneumoniae serotypes by polymerase chain reaction （PCR） and the Neufeld Quellung reaction,the multilocus sequence types （MLST） by PCR and sequencing,and susceptibility to antimicrobial agents by the VITEK Gram Positive Susceptibility Card.Results A total of 39 isolates were collected including 21 blood/CSF and 18 sputum isolates.Conventional serotyping by the Quellung reaction required 749 reactions.In contrast,PCR based typing needed only 106 PCR reactions.The most frequent serotypes from the blood/CSF isolates were 14 （38.1%）,19A （14.3%）,23F （9.5%）,and 18C （9.5%）.In the sputum isolates the most frequent serotypes were 19F （33.3%）,23F （16.7%）,19A （11.1%）,and 3 （11.1%）.The incidence of penicillin resistance in the blood/CSF and sputum isolates was 66.7% and 55.6%,respectively.Statistical analysis showed that patients ≤5 years old had a higher resistance to penicillin when they compared with the patients ≥65 years old （P=0.011）.Serotypes 14,19A and 19F were significantly associated with penicillin resistance （P 〈0.001）.ST320,ST271,and ST876 isolates showed high resistant rates to several antibiotics including penicillin （P=0.006）.All of the isolates of serotype 19A were resistant to both penicillin and erythromycin,and they were all multi-drug resistant （MDR） isolates.Conclusions The specificity and sensitivity of multiplexPCR are good,and this method represents a substantial savings of time and money,and can be widely used in the laboratory and clinical practice.Data from this research showed an extremely high prevalence of penicillin resistance and an increasing prevalence of multi-drug resistant （MDR） rate in S.pneumoniae.A distinctive emergence of serotype 19A was observed which was also associated with the increasing prevalence of antimicrobial resistance.Therefore,nationwide surveillance of pneumococcal resistance and serotypes is strongly warranted.

Molecular epidemiology of serotype 19A Streptococcus pneumoniae isolated from children in Beijing, 1997-2006

Background Despite the prevalence of Streptococcus pneumoniae serotype 19A, the molecular characteristics of this serotype are yet to be fully elucidated. The aim of this study was therefore to determine the homology of the serotype 19A in China. Methods Pulsed-field gel electrophoresis and multilocus sequence typing were done to these forty-nine serotype 19A isolates to investigate the relationship between the strains prevalent in Beijing and other regions. Results From 1997 to 2006, the percentage of serotype 19A isolates increased. The susceptibility rate to penicillin and amoxicillin decreased and the resistance rate to cefuroxime increased. ST320 was the most prevalent ST, followed by ST3546. There were six new STs identified in our study. The serotype 19A strains were classified into six different pulsed-field gel electrophoresis （PFGE） patterns. ST320, which was associated with two different PFGE patterns （A and D）, accounted for 32 isolates, and ST3546, which was associated with two PFGE patterns （B and E）, accounted for eight isolates. Conclusions From 2003 onwards, ST320 was the most common ST and the rate of resistance to cefuroxime increased significantly. Further long-term surveys of Streptococcus pneumoniae serotype 19A are required to monitor ST prevalence and antimicrobial resistance, in this important human pathogen.