Streptococcus pneumoniae nasopharyngeal colonization in young healthy children: rate of carriage,serotype distribution,and antibiotic resistance

The nasopharyngeal colonization rate of Streptococcus pneumoniae and its antibiotic susceptibility was determined in a given population of 317 young children (ages 1-7 years) in the area of Bari, Italy. 18.29% of the cultures were positive for S. pneumoniae. 8.62% of the strains were intermediately resistant to penicillin. Erythromycin-(65.51%) and cotrimoxazole-(17.24%) resistance was also observed whereas all the strains resulted uniformely susceptible to cefotaxime and ceftriaxone. The high rate of nasopharyngeal carriage of Streptococcus pneumoniae along with the resistance to antibiotics widely used in the community suggests the importance of epidemiological surveillance as well as the application of new vaccine strategies.     

Etiology of pulmonary diseases in children in Khabarovsk Region

Microflora of upper respiratory tract in 658 children aged 1 month - 17 years hospitalized with acute pneumonia (AP), acute bronchitis (AB), recurrent obstructive bronchitis (ROB), malformation of lungs (ML) and broncho-alveolar dysplasia (BALD) were studied. Carriage rates of Streptococcus pneumoniae (up to 95%) and Haemophilus influenzae (up to 89%) in 240 children attending daycare centers and schools were determined. Etiology of infectious process was ascertained in 40% of cases. S. pneumoniae was isolated in 45% of acute cases (AP and AB) and in 25% of chronic cases (BALD). H. influenzae was isolated in 8 - 12% of acute cases and in 32% of chronic cases. In 23 - 29% of all cases of pulmonary pathology in children persistence of Enterococcus faecium was determined. There were 13 different serotypes among isolated pneumococci. In patients with pneumonia the rate of detection of S. pneumoniae and H. influenzae DNA fragments by PCR was significantly higher compared with rate of their isolation from sputum.     

儿童感染青霉素耐药肺炎链球菌的 多位点序列分型

目的对儿童感染的青霉素耐药肺炎链球菌进行多位点序列分型,了解厦门地区肺炎链球菌青霉素耐药菌株遗传背景。方法采用多位点序列分型法对2012年1月至2014年12月期间分离的60株青霉素耐药肺炎链球菌进行分子分型。结果 60株青霉素耐药肺炎链球菌MLST法共检出24个ST型,其中发现6个新的ST型,分别被命名为ST10004、ST10005、ST10006、ST10007、ST10008和ST10009。存在一个优势型别ST271,占31.7%(19/60),发现了4个克隆群和20种单一克隆,其中主要克隆群为国际流行耐药克隆群Taiwan19F-14,占41.7%(25/60)。结论本地区分离的儿童青霉素耐药肺炎链球菌主要以ST271型为主,属国际流行耐药克隆群Taiwan19F-14,是引起儿童呼吸道感染肺炎链球菌多重耐药的主要原因。     

Bacteriostatic or bactericidal effect of linezolid against multiresistant Streptococcus pneumoniae

The nasopharynx plays a critical role as the reservoir of Streptococcus pneumoniae, including drug-resistant strains particularly in children attending day care centers. A total 58 nasopharyngeal, multiresistant isolates of S. pneumoniae collected from healthy pre-school children were susceptible to linezolid (MIC = 0.25-1 mg/l), irrespective of serotype and drug resistance pattern. The majority of them (about 94%) were sensitive to the bactericidal effect of linezolid with MBCs = 0.5-4 mg/l. One isolate was killed at 8 mg/l of linezolid, while two at higher concentrations of this antibiotic with MBCs 16 or 32 mg/l, suggesting tolerance of linezolid. BOX-PCR fingerprinting data imply that two linezolid-tolerant strains belonged to distinct clones. Linezolid tolerance was confirmed by monitoring the viability of these isolates during exposure to 4 or 20 mg/l of this antibiotic. The linezolid-tolerant strains were sensitive to the bactericidal effect of vancomycin. Linezolid tolerance in clinical isolates of pneumococci may represent a potential therapeutic risk, especially in infections in which bactericidal activity of drug is critical for eradication of bacteria.     

Nasal carriage of methicillin resistant Staphylococcus aureus and their antibiotic susceptibility patterns in children attending day-care centers

Nasal colonization with community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is being increasingly reported, especially in places where people are in close contact and in reduced hygiene, such as day-care centers. In this study we investigated the frequency of MRSA colonization and their antibiotic susceptibility patterns in 1-6 years old children of day-care centers in Hamadan, West of Iran.Five hundred nasal swabs were collected from children of 27 day-care centers that had no risk factors for colonization by S. aureus. The specimens were cultured for isolation of S. aureus by standard methods. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. For evaluation of the frequency of erythromycin induced clindamycin resistance, disk approximation test (D-test) was applied.Totally, 148 (29.6%) children were colonized by S. aureus. Out of 260 male, 94 (36.2%) and of 240 female, 54 (22.5%) cases were nasal carriers of S. aureus (P value = 0.001). Six (4.1%) of the 148 S. aureus isolated from children were MRSA strains. None of MRSA and methicillin susceptible S. aureus (MSSA) was resistant to vancomycin and clindamycin. Three of the 6 strains of MRSA and 7 (4.9%) of the 142 MSSA strains were resistant to erythromycin, and D-test was positive in all of them.We conclude that the rate of colonization by S. aureus is high in children attending day-care centers but colonization with MRSA is not common in our areas. Clindamycin or trimethoprim-sulfamethoxazol could be used in mild to moderataly severe diseases caused by CA-MRSA. However, if the CA-MRSA isolates are erythromycin resistant, D-test should be carried out for detection of inducible clindamycin resistance.     

产ESBLs肺炎克雷伯菌的基因型和耐药性研究

超广谱β-内酰胺酶(extended spectrumβ-lactamase,ESBLs)与细菌耐药性密切相关,为了揭示产ESBLs肺炎克雷伯菌的基因型和耐药性,本研究在2017年1月至2018年9月期间,共检测了466例肺炎克雷伯菌感染的患者标本,并分析了产ESBLs肺炎克雷伯菌的基因型和耐药性。研究结果显示,466例患者中共检出562个肺炎克雷伯菌菌株。其中,呼吸内科的检出数最多(212株,37.72%),其次为重症监护科(106株,18.86%)。对于不同标本来源,痰液中检出菌数最多(331株),占总数的58.90%。562株肺炎克雷伯菌中共检测出237株产ESBLs(42.17%)。产ESBLs肺炎克雷伯菌对阿莫西林(89.03%)、替卡西林(87.34%)、氨苄西林(81.43%)的耐药率最高;而对替加环素(9.28%)、阿米卡星(6.75%)、亚胺培南(1.27%)和美罗培南(0.84%)的耐药率最低。237株产ESBLs的肺炎克雷伯菌菌株中,53.59%扩增出CTX-M型,48.95%扩增出TEM型,40.93%增出SHV型。另外,237株产ESBLs的肺炎克雷伯菌菌株中,产两个及以上的ESBLs的菌株共111株(46.84%)。     

Mathematical model comparisons of potential non-typeable Haemophilus influenzae vaccine effects

Vaccines to prevent acute otitis media (AOM) caused by non-typeable Haemophilus influenzae (NTHi) are under development. Because NTHi is highly variable and colonization rates are high, special vaccine characteristics and trial designs might be needed. We examined in mathematical models the equilibrium NTHi-caused AOM rate given hypothetical vaccines that generated immunity identical to corresponding maximal naturally acquired immunity. Vaccines were examined with single effects and combinations of immunity affecting (1) AOM rates given colonization (pathogenicity), (2) susceptibility to colonization, and (3) contagiousness given colonization. Percent reductions in AOM across all preschool children were (1) 34%, (2) 31%, (3) 9%, (1 and 2) 57%, (2 and 3) 50%, and (1, 2, and 3) 75%. Effects on children in daycare vs. not in daycare were (1) 18 vs. 48%, (2) -1 vs. 57%, (3) 13 vs. 5%, (1 and 2) 30 vs. 79%, (2 and 3) 33 vs. 60%, and (1, 2, and 3) 64 vs. 85%. Pure pathogenicity effects (1 alone) will need to be supplemented by transmission effects. The effects of susceptibility (2 alone) are diminished or negative because children protected against colonization have lower levels of immunity to (1) and (3) than unvaccinated children. For trials to predict population effects, both colonization and AOM outcomes must be studied and all three effects must be evaluated. This need arises because, unlike H. influenzae type B, high NTHi exposure diminishes cumulative vaccine effects and high colonization rates generate rapid accumulation of natural immunity that alters the indirect effects of vaccine immunity on transmission differently by age and daycare status.     

Pneumococcal meningitis in childhood: a longitudinal prospective study

After implementation of programmes for active immunization against Haemophilus influenzae b, Streptococcus pneumoniae and Neisseria meningitidis became the most common agents of bacterial meningitis in childhood. Over a 9-year period, children showing clinical and laboratory findings of meningitis on the basis of their positive cultures of blood or cerebro-spinal fluid (CSF) for S. pneumoniae were enrolled. Predisposing conditions, clinical and laboratory findings, and microbiological and imaging studies were considered. Meningitis-related death or neurological sequelae defined an unfavourable outcome. Sixty-four patients met the inclusion criteria. Thirty-one (48%) children had predisposing conditions to pneumococcal meningitis. Fever and neck stiffness were the main symptoms; 14 patients (22%) reported seizures before admission. Twenty-one patients required treatment in the intensive care unit (ICU). Streptococcus pneumoniae strains were penicillin susceptible in 54 cases (84%). Forty-eight children (75%) showed complete recovery. Two patients (3%) died, and 14 (22%) had sequelae. Patients with a low CSF cell count, low neutrophils, early admission to ICU or infection by penicillin-nonsusceptible strains of S. pneumoniae had an unfavourable outcome more frequently. Low blood neutrophils, low CSF cell count, early admission to ICU and infection by penicillin-nonsusceptible strains are the main factors predicting an unfavourable outcome in children with pneumococcal meningitis.     

肺炎链球菌溶血素黏膜免疫抗定植保护作用的研究

目的原核表达△A146Ply蛋白,评价△A146Ply黏膜免疫对肺炎链球菌（Streptococcuspneumon—ioe,5．Pn）在宿主鼻咽部定植的保护作用。方法IPTG诱导、Ni—NTA树脂纯化获得纯化的△A146Ply蛋白,经黏膜免疫BALB／C小鼠,制备其特异性抗血清;进行体内抗定植实验,观察小鼠鼻咽部灌洗液和肺部残存的细菌数量,检测△A146Ply黏膜免疫对19F型肺炎链球菌在鼻咽部定植的保护作用。为验证该保护作用是否具有广谱性,培养血清型14型、3型、6型和2型S．pn,经鼻腔感染免疫后小鼠,评价△A146Ply蛋白黏膜免疫对多株肺炎链球菌定植的保护作用。进行体外抗黏附实验,检测△A146Ply蛋白及其抗血清是否对无荚膜的肺炎链球菌R6黏附A549细胞具有抑制作用。结果获得了纯度〉90％的目的蛋白;体内实验结果显示,△A146Ply黏膜免疫可以显著降低肺炎链球菌19F在宿主鼻咽部和肺部残存的细菌数量（P〈0．01）;14型和3型肺炎链球菌在免疫后小鼠鼻咽部及肺部定植的数量均显著下降（P〈0．05）,2型肺炎链球菌在免疫后小鼠肺部定植的数量显著下降（P〈0．05）,6B型肺炎链球菌在免疫组与对照组小鼠鼻咽部及肺部均无显著差异（P〉0．05）;△A146Ply特异性抗血清△A146Ply蛋白对R6黏附A549细胞的抑制效应呈剂量依赖性。结论△A146Ply蛋白经黏膜免疫BALB／C小鼠可以对多种血清型的肺炎链球菌在宿主鼻咽部及肺部的定植提供显著保护作用,为Ply作为肺炎链球菌疫苗候选蛋白的应用提供了实验依据。     

Upper respiratory tract microbial communities, acute otitis media pathogens, and antibiotic use in healthy and sick children

The composition of the upper respiratory tract microbial community may influence the risk for colonization by the acute otitis media (AOM) pathogens Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. We used culture-independent methods to describe upper respiratory tract microbial communities in healthy children and children with upper respiratory tract infection with and without concurrent AOM. Nasal swabs and data were collected in a cross-sectional study of 240 children between 6 months and 3 years of age. Swabs were cultured for S. pneumoniae, and real-time PCR was used to identify S. pneumoniae, H. influenzae, and M. catarrhalis. The V1-V2 16S rRNA gene regions were sequenced using 454 pyrosequencing. Microbial communities were described using a taxon-based approach. Colonization by S. pneumoniae, H. influenzae, and M. catarrhalis was associated with lower levels of diversity in upper respiratory tract flora. We identified commensal taxa that were negatively associated with colonization by each AOM bacterial pathogen and with AOM. The balance of these relationships differed according to the colonizing AOM pathogen and history of antibiotic use. Children with antibiotic use in the past 6 months and a greater abundance of taxa, including Lactococcus and Propionibacterium, were less likely to have AOM than healthy children (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.25 to 0.85). Children with no antibiotic use in the past 6 months, a low abundance of Streptococcus and Haemophilus, and a high abundance of Corynebacterium and Dolosigranulum were less likely to have AOM (OR, 0.51; 95% CI, 0.31 to 0.83). An increased understanding of polymicrobial interactions will facilitate the development of effective AOM prevention strategies.     

Xylitol chewing gum in prevention of acute otitis media: double blind randomised trial.

OBJECTIVE: To examine whether xylitol, which reduces the growth of Streptococcus pneumoniae, might have clinical importance in the prevention of acute otitis media. DESIGN: A double blind randomised trial with xylitol administered in chewing gum. SETTING: Eleven day care nurseries in the city of Oulu. Most of the children had had problems with recurrent acute otitis media. SUBJECTS: 306 day care children: 149 children in the sucrose group (76 boys; mean (SD) age 4.9 (1.5) years) and 157 in the xylitol group (80 boys; 5.0 (1.4) years). INTERVENTION: Either xylitol (8.4 g a day) or sucrose (control) chewing gum for two months. MAIN OUTCOME MEASURES: The occurrence of acute otitis media and antimicrobial treatment received during the intervention and nasopharyngeal carriage of S pneumoniae. RESULTS: During the two month monitoring period at least one event of acute otitis media was experienced by 31/149 (20.8%) children who received sucrose compared with 19/157 (12.1%) of those receiving chewing gum containing xylitol (difference 8.7%; 95% confidence interval 0.4% to 17.0%; P = 0.04). Significantly fewer antimicrobials were prescribed among those receiving xylitol: 29/157 (18.5%) children had at least one period of treatment versus 43/149 (28.9%) (difference 10.4%; 0.9% to 19.9%; P = 0.032). The carriage rate of S pneumoniae varied from 17.4% to 28.2% with no difference between the groups. Two children in the xylitol group experienced diarrhoea, but no other adverse effects were noted among the xylitol users. CONCLUSION: Xylitol seems to have a preventive effect against acute otitis media.     

Respiratory syncytial virus infections during an epidemic period in Salvador, Brazil. Viral antigenic group analysis and description of clinical and epidemiological aspects

Acute respiratory infections (ARI) caused by respiratory syncytial virus (RSV) were studied in 482 children from Salvador, BA, Brazil, over a period of 12 months. The epidemic period of RSV infections in Salvador occurred from February (summer) to August (winter), with peaks in May, June, and July. The grouping characteristics of 84 RSV present in nasopharyngeal secretions of children seen at a reference university hospital were analyzed. RSV represented 17.4% of all cases and 54.5% of the positive samples. Sixty-four RSV strains were assigned to group A and 14 to group B. Both groups circulated in the five months of the epidemic period studied. Infections by both groups of RSV were more frequent in children up to one year of age. The incidence of RSV ARI was slightly more frequent in males, although group B had more infected females.     

Microbiological control of drug resistance of causative agents in suppurative-septic infections in newborn infants

Resistance of the main causative agents of purulent septic infections such as pneumonia, meningitis, sepsis, etc. to 11 chemotherapeutic drugs was studied. The pathogens were isolated from autopsies of 203 newborns who died within 1981 to 1987. Among 2978 isolates belonging to Enterobacteriaceae (2466 strains) and Pseudomonadaceae (512 strains) which constituted 88% of all the isolates, strains with multiple resistance predominated: 90% of the strains resistant to 4 or more antibiotics, 77% of the strains resistant to 6 or more antibiotics and 48% of the strains resistant to 8 or more antibiotics. The highest number of the isolates were resistant to 8 and 9 chemotherapeutics (19 and 20%, respectively). 84% of all the isolates belonged to 4 genera: Klebsiella (34%), Escherichia (21%), Serratia (14%) and Pseudomonas (15%). They were characterized by the highest resistance spectra. In all the cases massive colonization of the intestine by the strains with multiple resistance which caused purulent septic infections was observed. The most frequent variants of the drug resistance combination were determined. In the total frequency of the isolate with multiple resistance no significant differences were detected in 1981 and thereafter. In 1986-1987 the frequency of S. marcescens strains increased 3-5 times with simultaneous broadening of their drug resistance spectra. Strains of S. marcescens and K. pneumoniae with multiple drug resistance endemic for definite hospitals were detected.     

儿童副流感病毒、肺炎支原体感染情况研究

摘要 目的：通过检测及分析住院患儿血清中副流感病毒、肺炎支原体IgM抗体,探讨两种病原体感染的流行病学特征。方法：应用酶联免疫分析的方法定性检测患儿血清中的副流感病毒、肺炎支原体IgM抗体,采用卡方检验对不同年份、性别、年龄及季节的数据进行分析。结果：副流感病毒、肺炎支原体阳性率分别为3.6%、22.4%,混合感染的阳性率为1.3%。PIV每年女性患儿比男性患儿阳性率高,每一年中6-14岁感染阳性率最高;MP每年女性患儿比男性患儿阳性率高,随着年龄增长感染的阳性率也升高,6-14岁阳性率最高。PIV与MP在每年的四季中,感染的阳性率各不相同,并且没有相对的规律可循,但是在冬季阳性率还是较高,其次是春季、秋季,最低的是夏季。结论：掌握儿童副流感病毒和肺炎支原体感染流行病学特点,有助于了解疾病感染特点,从而在疾病的不同时期及时快速地采取相应措施。     

T(H)17-based vaccine design for prevention of Streptococcus pneumoniae colonization

Streptococcus pneumoniae is a leading cause of mortality in young children. While successful conjugate polysaccharide vaccines exist, a less expensive serotype-independent protein-based pneumococcal vaccine offers a major advancement for preventing life-threatening pneumococcal infections, particularly in developing nations. IL-17A-secreting CD4+ T cells (T(H)17) mediate resistance to mucosal colonization by multiple pathogens including S. pneumoniae. Screening an expression library containing >96% of predicted pneumococcal proteins, we identified antigens recognized by T(H)17 cells from mice immune to pneumococcal colonization. The identified antigens also elicited IL-17A secretion from colonized mouse splenocytes and human PBMCs suggesting that similar responses are primed during natural exposure. Immunization of two mouse strains with identified antigens provided protection from pneumococcal colonization that was significantly diminished in animals treated with blocking CD4 or IL-17A antibodies. This work demonstrates the potential of proteomic screening approaches to identify specific antigens for the design of subunit vaccines against mucosal pathogens via harnessing T(H)17-mediated immunity.     

Versatility of the capsular genes during biofilm formation by Streptococcus pneumoniae

Streptococcus pneumoniae forms part of the natural microbiota of the nasopharynx. For the pneumococcus to cause infection, colonization needs to occur and this process is mediated by adherence of bacteria to the respiratory epithelium. Although the capsular polysaccharide (CPS) of S. pneumoniae is known to be important for infection to occur, its role in colonization is controversial. Biofilm models are starting to emerge as a promising tool to investigate the role of CPS during nasopharyngeal carriage, which is the first step in the dissemination and initiation of a pneumococcal infection. Using a well-defined model system to analyse in vitro biofilm formation in pneumococcus, here we explore the molecular changes underlying the appearance of capsular mutants using type 3 S. pneumoniae cells. Spontaneous colony phase variants show promoter mutations, as well as duplications, deletions and point mutations in the cap3A gene, which codes for a UDP-glucose dehydrogenase (UDP-GlcDH). Increased biofilm-forming capacity could usually be correlated with a reduction both in colony size and in the relative amount of CPS present on the cell surface of each colony variant. However, a mutation in Cap3A Thr83Ile (a strictly conserved residue in bacterial UDP-GlcDHs) that resulted in very low CPS production also led to impaired biofilm formation. We propose that non-encapsulated mutants of pneumococcal type 3 strains are essentially involved in the initial stages (the attachment stage) of biofilm formation during colonization/pathogenesis.     

The frequency of staphylococcal colonization of the intestines in children with the manifestations of dysbacteriosis

In 2100 children of different age groups the microbiocenosis of the large intestine was studied. The study revealed that the colonization of the mucous membrane of the large intestine with staphylococci developed in 30% of children with intestinal dysbacteriosis. Young children were mainly affected (91%). The prevailing species among isolated staphylococci was S. aureus (86%), capable of persistence in the intestine (30.9%). In children non typing S. aureus strains mainly circulated (70%), and among phage-typing strains isolates of phage group III prevailed (70.2%). The colonization of the intestine with coagulase-negative staphylococci was possible (14%). Microecological intestinal disturbances in children of different age groups were characterized by different degrees of changes in normal microflora with the prevalence of opportunistic microorganisms in the microbial picture.     

Role of Staphylococcus aureus catalase in niche competition against Streptococcus pneumoniae

Nasal colonization by Staphylococcus aureus is a major predisposing factor for subsequent infection. Recent reports of increased S. aureus colonization among children receiving pneumococcal vaccine implicate Streptococcus pneumoniae as an important competitor for the same niche. Since S. pneumoniae uses H2O2 to kill competing bacteria, we hypothesized that oxidant defense could play a significant role in promoting S. aureus colonization of the nasal mucosa. Using targeted mutagenesis, we showed that S. aureus expression of catalase contributes significantly to the survival of this pathogen in the presence of S. pneumoniae both in vitro and in a murine model of nasal cocolonization.