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.

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.

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.

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.

Prevalence of antimicrobial resistance of Streptococcus pneumoniae in Chinese children: four hospitals surveillance

Objective To investigate the nasal carriage of antibiotic-resistant pneumococci in children of < 5 years old in the following four cities, Beijing, Shanghai, Guangzhou and Xi' an.Methods A total of 647 pneumococci strains were isolated and detected. Minimal inhibition concentrations (MICs) of antibiotics were determined by E-test. Disk diffusion test was used for the measurement of antimicrobial susceptibility.Results Prevalence of penicillin non-susceptible Streptococcus pneumoniae in the four cities was 41%, with Guangzhou (60.8%) ranking first, followed by Xi' an (45%), Shanghai (37%) and Beijing (25. 9%). The majority of penicillin non-susceptibility isolates (23. 9% -53. 8%) had a low level of resistance (MIC 0. 64 -1. 5 μg/ml). The most sensitive antimicrobials in terms of percentage of susceptible organisms were amoxicillin-clavulanic acid ( 99.4%), followed by ceftriaxone (92. 1 %); cefurxime and cefaclor were slightly more sensitive than penicillin with susceptibility of 74. 8% and 77. 9%. Erythromycin, tetracycline and TMP-SMZ were highly resistant (83. 6% , 82. 1% and 76.2% respectively) . Among erythromycin resistant isolates, 100% were resistant to azithromycin, 98.6% to clarithromycin, 97.2% to roxithromycin and spiramycin, and 96.6% to clindamycin. 97.2% (141/145) were typical of the macrolides-lincosamides-streptogramons B (MLSB ) resistance phenotype, and 2. 8% (4/145) were M phenotype. The group of PRSP was with significantly higher rates of non-susceptibility for ceftriaxone (18. 4%), cefurxime (58. 6%), cefaclor (53. 4%), compared with the group of PEN-S (0. 5% , 1.8% and 0. 2% , respectively) and the rate of multi-drug resistance in the isolates of PRSP group (92. 9%) was significantly higher than that of PEN-S group (59.2%).Conclusion The rates of penicillin and multi-drug resistance among isolates of pneumococci carried nasally in are high children and the high prevalence of multi-drug resistance in the Chinese population may be becoming one of the most serious problems in this century.

PENTOXIFYLLINE AMELIORATES PULMONARY DAMAGE CAUSED BY STREPTOCOCCUS PNEUMONIAE INFECTION IN MOUSE

Streptococcus pneumoniae stimulated mouse peritoneal macrophagc to release tumor necrosis factor-α (TNFα) in vitro. When penicillin was added into the medium with bacteria, TNFα release was accelerated. Pentoxifylline (PTX), a phosphodiesterase inhibitor, significantly attenuated TNFα release caused either by Streptococcus pneumoniae or by its lysates. In this experiment, 150 Kunming mice were infected with Streptococcus peumoniae through inspiration. Dynamic changes of TNFα concentration in serum and bronchoalveolar lavage fluid were determined, and pulmonary pathological changes were also observed. It was found that PTX significantly attenuated TNFα activity in serum and bronchoalveolar lavage fluid, and inhibited white blood cell chemotaxis, emigration and infiltration. In conclusion, Streptococcus pneumoniae infection stimulates the release of TNFα which is probably the major mediater that causes tissue damage during Streptococcus pneumoniae infection. The mechanism is probably that Steptococcus pneumoniae and its lysates activate TNFα gene transcription. As penicillin accelerates TNFα release, treatment with penicillin alone may aggravate the tissue damage. Combined treatment with PTX may be more reasonable.

Hematocrit is associated with in-hospital mortality in sepsis with streptococcus pneumoniae infection based on MIMIC-Ⅳ database

Background Streptococcus pneumoniae,as a respiratory tract common pathogen,can cause invasive disease and sepsis.This study aimed to investigate the association of factors with clinical outcomes in sepsis with streptococcus pneumoniae infection based on MIMIC-IV database.Methods The sepsis patients with streptococcus pneumoniae infection were included.Different variables between the survivor group and the non-survivor group were analyzed.Multivariable logistic regression was applied to identify the factors which were associated with clinical outcomes.Results A total of 80 sepsis patients with streptococcus pneumoniae infection were included.The in-hospital mortality was 23.75%(n=19).Significant differences were found in heart rate,white blood cell,RDW,MCV and hematocrit between the survivor group and the non-survivor group.The area under the ROC curve of hematocrit was 0.758 with a sensitivity of 73.7%and a specificity of 72.1%.The cut-off value of hematocrit was 30.8%.Conclusions Hematocrit level was identified to be negatively associated with in-hospital mortality in sepsis with streptococcus pneumoniae infection.

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.

Characterization of erythromycin-resistant Streptococcus pneumoniae isolates causing invasive diseases in Chinese children

Background Erythromycin-resistant Streptococcus pneumoniae isolates that causing invasive pneumococcal diseases （IPD） in Chinese children remain uncharacterized. This study aims to identify the resistance genes associated with erythromycin resistance and to determine the genetic relationships of IPD isolates in Chinese children. Methods A total of 171 S. pneumoniae strains were isolated from 11 medical centers in China from 2006 to 2008. All the isolates were characterized via serotyping and antibiotic susceptibility determination. The erythromycin-resistant isolates were further characterized via ermB and mefA gene detection, multi-locus sequence typing analysis, and pulsed-field gel electrophoresis. Results A total of 164 （95.9%） isolates showed resistance to erythremycin, of which 162 strains with high high-level resistance （MIC 〉 256 pg/ml）. A total of 104 （63.4%） isolates carry the ermB gene alone, whereas 59 （36.0%） harbor both ermB and mefA genes. Of the 59 strains, 54 were of serotypes 19A and 19F and were identified as highly clonal and related to the TaiwanlgF-14 clone. Conclusions The erythromycin resistance rate in IPD isolates is significantly high and is predominantly mediated by the ermB aene. Isolates that carrv both ermB and mefA Qenes are oredominantlv of serotvoes 19A and 19E

STREPTOCOCCUS PNEUMONIAE KERATITIS FOLLOWING LASER IN SITU KERATOMILEUSIS

A 22-year-old man underwent bilateral laser in situ keratomileusis and developed Streptococcus pneumoniae keratitis after surgery.This complication occurred one day after the procedure in both eyes.Topical and systemic antibiotics were promptly administered.Bacterial culture was performed following corneal flap lift and scraping of the lesions.Afterwards,the therapeutic regimen was readjusted according to the culture results.Streptococcus pneumoniae was identified from the culture.Three months after the surgery,corrected distance visual acuity achieved 20/20 in both eyes.Streptococcus pneumoniae can affect the cornea following LASIK.As prompt treatment is crucial,we recommend,for acute and subacute cases,systemic and topical application of vancomycin or moxifloxacin before the culture results come out.

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.

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.