Neisseria meningitidis with decreased susceptibility to penicillin in Istanbul, Turkey

This study was conducted to estimate the rate of decreased susceptibility to penicillin (MIC > 0.06-1 microg/ml) in Neisseria meningitidis isolates in Istanbul, Turkey. A total of 30 isolates collected during a 1-y period from patients with meningitis and from nasopharyngeal carriers were tested for penicillin and cefotaxime susceptibility using the E-test. Two out of 12 (17%) clinical isolates and 11/18 (61%) nasopharyngeal isolates showed decreased susceptibility to penicillin with MICs in the range 0.094-1.0 microg/ml, giving an overall resistance of 43% (n = 13). These data show that continued surveillance of trends in antimicrobial susceptibility of N. meningitidis is important for detecting the emergence of N. meningitidis strains with MICs > 1 microg/ml which may pose serious therapeutic problems.     

Recruitment of a penicillin-binding protein gene from Neisseria flavescens during the emergence of penicillin resistance in Neisseria meningitidis.

Non-beta-lactamase-producing, penicillin-resistant strains of Neisseria meningitidis produce altered forms of penicillin-binding protein 2 that have decreased affinity for penicillin. The sequence of the penicillin-binding protein 2 gene (penA) from a penicillin-resistant strain of N. meningitidis was compared to the sequence of the same gene from penicillin-sensitive strains and from penicillin-sensitive and penicillin-resistant strains of Neisseria gonorrhoeae. The penA genes from penicillin-sensitive strains of N. gonorrhoeae and N. meningitidis were 98% identical. The gene from the penicillin-resistant strain of N. meningitidis consisted of regions that were almost identical to the corresponding regions in the penicillin-sensitive strains (less than 0.2% divergence) and two regions that were very different from them (approximately 22% divergence). The two blocks of altered sequence have arisen by the replacement of meningococcal sequences with the corresponding regions from the penA gene of Neisseria flavescens and result in an altered form of penicillin-binding protein 2 that contains 44 amino acid substitutions and 1 amino acid insertion compared to penicillin-binding protein 2 of penicillin-sensitive strains of N. meningitidis. A similar introduction of part of the penA gene of N. flavescens, or a very similar commensal Neisseria species, appears to have occurred independently during the development of altered penA genes in non-beta-lactamase-producing penicillin-resistant strains of N. gonorrhoeae.     

Genetic diversity of penicillin-resistant Neisseria meningitidis.

The genetic relatedness of 42 penicillin-resistant Neisseria meningitidis isolates obtained during a 2-year period from a single hospital was studied by multilocus enzyme electrophoresis and by restriction fragment length polymorphism (RFLP) analysis of penicillin-binding protein (PBP) 2 genes. The PBP 2 genes of 7 susceptible strains gave identical RFLP profiles. Sixteen different PBP 2 RFLP profiles were found among the 42 resistant strains, but 4 were found in greater than 1 resistant isolate. Multilocus enzyme electrophoresis revealed a high level of genetic diversity. Four clusters of resistant strains could be distinguished at a genetic distance of 0.75. Resistant strains with the most common PBP 2 RFLP profile were restricted to one of these clusters and may be derived from a common ancestral strain. However, resistant strains with the 3 other common RFLP profiles were distributed in two or more of the clusters.     

Penicillin-resistant viridans streptococci have obtained altered penicillin-binding protein genes from penicillin-resistant strains of Streptococcus pneumoniae

Penicillin-resistant strains of Streptococcus pneumoniae possess altered forms of penicillin-binding proteins (PBPs) with decreased affinity for penicillin. The PBP2B genes of these strains have a mosaic structure, consisting of regions that are very similar to those in penicillin-sensitive strains, alternating with regions that are highly diverged. Penicillin-resistant strains of viridans groups streptococci (e.g., S. sanguis and S. oralis) that produce altered PBPs have also been reported. The PBP2B genes of two penicillin-resistant clinical isolates of S. sanguis were identical in sequence to the mosaic class B PBP2B genes found in penicillin-resistant serotype 23 strains of S. pneumoniae. Emergence of penicillin resistance appears to have occurred by the horizontal transfer of an altered PBP2B gene from penicillin-resistant S. pneumoniae into S. sanguis. The PBP2B genes of three penicillin-resistant S. oralis strains were similar to the mosaic class B PBP2B gene of penicillin-resistant strains of S. pneumoniae but possessed an additional block of diverged sequence. Penicillin resistance in S. oralis has also probably arisen by horizontal transfer of this variant form of the class B mosaic PBP2B gene from a penicillin-resistant strain of S. pneumoniae.     

Whole-genome comparison of disease and carriage strains provides insights into virulence evolution in Neisseria meningitidis

Neisseria meningitidis is a leading cause of infectious childhood mortality worldwide. Most research efforts have hitherto focused on disease isolates belonging to only a few hypervirulent clonal lineages. However, up to 10% of the healthy human population is temporarily colonized by genetically diverse strains mostly with little or no pathogenic potential. Currently, little is known about the biology of carriage strains and their evolutionary relationship with disease isolates. The expression of a polysaccharide capsule is the only trait that has been convincingly linked to the pathogenic potential of N. meningitidis. To gain insight into the evolution of virulence traits in this species, whole-genome sequences of three meningococcal carriage isolates were obtained. Gene content comparisons with the available genome sequences from three disease isolates indicate that there is no core pathogenome in N. meningitidis. A comparison of the chromosome structure suggests that a filamentous prophage has mediated large chromosomal rearrangements and the translocation of some candidate virulence genes. Interspecific comparison of the available Neisseria genome sequences and dot blot hybridizations further indicate that the insertion sequence IS1655 is restricted only to N. meningitidis; its low sequence diversity is an indicator of an evolutionarily recent population bottleneck. A genome-based phylogenetic reconstruction provides evidence that N. meningitidis has emerged as an unencapsulated human commensal from a common ancestor with Neisseria gonorrhoeae and Neisseria lactamica and consecutively acquired the genes responsible for capsule synthesis via horizontal gene transfer.     

Antibiotic resistance of Neisseria species in Iran: A systematic review and meta-analysis

Objective: To estimate the prevalence of antibiotic resistance of Neisseria species in Iran. Methods: A systematic and electronic search using relevant keywords in major national and international databases was performed until 6th July, 2018 in order to find studies reporting the prevalence of antibiotic resistance of Neisseria species in Iran. Results: A total of nine studies were found to be eligible based on predefined inclusion and exclusion criteria. Our analysis indicated that the prevalence of Neisseria gonorrhoeae resistance to different antibiotics was as follows: 66.9% to penicillin, 59.1% to ciprofloxacin, 11.1% to ceftriaxone, 21.6% to spectinomycin, 13.8% to cefixime, 82.4% to co-trimoxazole, 52.7% to tetracycline, 29.9% to gentamicin, 87.5% to ampicillin, 11.1% to azithromycin, 2.2% to chloramphenicol, 50.1% to cefepime and 50.0% to vancomycin. Antimicrobial resistance rates of Neisseria meningitidis was as follows: 30.0% to penicillin, 33.3% to amoxicillin, 33.3% to cephalexin, 55.6% to ampicillin and 0.0% to ciprofloxacin, ceftriaxone, cefotaxime, amikacin, co-trimoxazole, gentamicin, kanamycin, chloramphenicol and ceftizoxime. Conclusion: Neisseria gonorrhoeae and Neisseria meningitidis isolates of Iran show resistance to different types of antibiotics. Therefore, care should be exercised for the use of penicillin, ciprofloxacin, co-trimoxazole, tetracycline, gentamicin, ampicillin, cefepime and vancomycin for gonococcal infections, and also with respect to the use of penicillin, amoxicillin, ampicillin and cephalexin for meningococcal infections in Iran.     

Neisseria lactamica meningitis following skull trauma

A woman developed meningitis due to Neisseria lactamica in association with a cribriform plate fracture. Cerebrospinal fluid antigen tests for Neisseria meningitidis were negative. The patient recovered with intravenous penicillin therapy. N. lactamica can be rapidly distinguished from N. meningitidis by the hydrolysis of ONPG (o-nitrophenyl-beta-D-galactopyranoside). In contrast to N. meningitidis and Neisseria gonorrhoeae, N. lactamica lacks virulence properties. As 100% of N. lactamica strains are susceptible to penicillin and all three previously described patients with N. lactamica meningitis have recovered with penicillin treatment, the reason for distinguishing the organisms in this context is primarily to prevent unnecessary anxiety and prophylaxis among contacts.     

An unusual Neisseria isolated from conjunctival cultures in rural Egypt

Seven isolates of an unusual Neisseria sp. were obtained from eye cultures of children in two rural Egyptian villages. These Neisseria utilized only glucose, they exhibited a positive reaction when tested with antisera to crude antigen from Neisseria meningitidis and N. gonorrhoeae, and they did not react with the fluorescent antibody tests for N. gonorrhoeae or with the monoclonal antibodies used to serotype gonococci. The Egyptian isolates had colony morphology more typical of meningococci than gonococci and showed opaque and transparent colony variants. On SDS-PAGE, the major outer-membrane proteins had different patterns than those noted for comparable proteins of meningococci and gonococci; heat-modifiable outer-membrane proteins were present. Four of the six isolates examined had cryptic plasmids of 2.8 megadaltons, which were slightly larger than the cryptic plasmid of N. gonorrhoeae. These plasmids were homologous to the gonococcal cryptic plasmid, but had different restriction enzyme fragment patterns. The DNA from the Egyptian isolates, like DNA from N. meningitidis but unlike DNA from N. gonorrhoeae, could be cut with the restriction enzyme HaeIII. The frequency of transformation into a temperature-sensitive mutant of N. gonorrhoeae was 0.2 for the Egyptian isolates and 0.1 for N. meningitidis, a frequency that was 5-10-fold lower than that for the N. gonorrhoeae control isolates. Whole-cell DNA from the Egyptian isolates showed 68%-73% homology with N. gonorrhoeae and 57%-63% with N. meningitidis. On the basis of our observations, the Egyptian isolates are distinct from N. meningitidis and may represent a variant of N. gonorrhoeae. We suggest that the isolates be called Neisseria gonorrhoeae ssp. kochii.     

Conjugation of plasmids of Neisseria gonorrhoeae to other Neisseria species: potential reservoirs for the beta-lactamase plasmid

The discovery that penicillinase production in Neisseria gonorrhoeae was plasmid mediated and the spread of the beta-lactamase encoding plasmids in gonococcal isolates since 1976, raise the possibility that a nonpathogenic indigenous bacterium could serve as a reservoir for these plasmids. We initiated studies to define the ability of commensal Neisseria species and Branhamella catarrhalis strains, as well as strains of the pathogen Neisseria meningitidis, to serve as recipients in conjugation with Neisseria gonorrhoeae. We found that with N. gonorrhoeae as the donor, 3 of 5 Neisseria cinerea, 2 of 5 Neisseria flava, 0 of 1 Neisseria flavescens, 1 of 3 Neisseria subflava, 0 of 6 B. catarrhalis, 0 of 7 Neisseria lactamica, 1 of 5 Neisseria mucosa, 1 of 7 Neisseria perflava/sicca, and 0 of 13 N. meningitidis strains gave detectable conjugation frequencies (greater than 10(-8). N. cinerea was the only species found to maintain the gonococcal conjugal plasmid (pLE2451). A N. cinerea transconjugant containing pLE2451 was observed to transfer both the beta-lactamase plasmid and pLE2451 to N. gonorrhoeae at high frequency.     

Mechanisms of resistance to growth inhibition and killing by beta-lactam antibiotics in enterococci.

Enterococci are characterized by an intrinsic resistance to growth inhibition by beta-lactam antibiotics. The low susceptibility of enterococci to beta-lactam antibiotics is associated with the synthesis of a particular penicillin-binding protein (PBP) that has a low affinity for beta-lactam agents. This protein appears to be capable of taking over the function of the other PBPs when they are saturated with beta-lactam molecules or inactivated by mutations. A quantitative correlation can be established between the binding of several beta-lactam molecules to the low-affinity PBP and the minimal inhibitory concentration for enterococcal strains. In contrast, the mechanism of enterococcal resistance to the bactericidal activity of beta-lactam agents that inhibit growth at relatively low concentrations appears to be associated with an alteration in the pattern of autolytic enzyme activity. In particular, lack of or poor activity of an autolytic enzyme appears to be responsible for the paradoxical bactericidal response often exhibited by clinical isolates of Enterococcus faecalis in the presence of penicillin.     

Genomic analysis of penicillin-resistant Streptococcus pneumoniae in Southeastern Michigan

OBJECTIVE: The emergence of multidrug resistance within Streptococcus pneumoniae population was analysed, correlating penicillin resistance Pen(R) with secondary antibiotic resistance, capsular serotype, and genetic diversity among isolates. METHODS: DNA fingerprinting, following macro-restriction enzyme digestion and pulse field gel electrophoresis (PFGE), and restriction fragment analysis of the PBP 2b gene, following PCR amplification, were performed on the Pen(R) S. pneumoniae, among 377 clinical isolates obtained from the clinical microbiology laboratory (University of Michigan Medical Center). RESULTS: Overall 35% of the isolates were Pen(R) of which 45% demonstrated high-level penicillin (Pen(R)-R, MIC>1). Respiratory isolates were more likely to be Pen(R) (p <0.001) than non-respiratory isolates and the rate of Pen(R)-R was significantly increased in children <10 years of age (59.6%, p <0.02). Secondary antibiotic resistance was more frequently associated with Pen(R)-R. Genomic DNA fingerprinting analysis and restriction fragment analysis of the PBP 2b gene demonstrated genomic divergence with discrete conserved pattern in the PBP 2b gene among the resistant isolates. CONCLUSION: The emergence of multidrug resistance in the S. pneumoniae population in SE Michigan is not due to expansion of a single or limited number of resistant clones, is occurring most frequently in the paediatric population and is associated with a decreased susceptibility to penicillin.     

Meta-analysis of antibiotic susceptibility and the genotype of penicillin-binding proteins in Streptococcus pneumoniae

To further understanding of the mechanisms of development of resistance to penicillin in Streptococcus pneumoniae, and the role of penicillin-binding proteins (PBPs) mutations to antibiotics resistance a meta-analysis was performed. Major databases, Pubmed, Current Contents, Biosis previews, Web of Science, were searched for studies that published within 1997 through to 2007, and reported the penicillin MIC and the alteration of PBP 1a, 2b and 2x (genes or proteins) of clinical S. pneumoniae isolates. Papers were reviewed by 2 persons and used standard criteria to enroll them. Meta-analysis was performed using a random-effects model. Overall, 20 studies were included in the meta-analysis. For the included 1771 clinical S. pneumoniae isolates, the susceptibility to penicillin decreased in inverse proportion to the presence of mutated pbp genes. The mutations of the conserved amino acid motifs STMK and SRNVP of PBP 1A, STMK and LKSG of PBP2X, and SSNT of PBP2B are critical for the penicillin resistance. Those motifs can be used as markers for the penicillin susceptibility of S. pneumoniae. These results are useful in helping define the mechanism of penicillin resistance in S. pneumoniae.     

细菌性脑膜炎病原菌分布和耐药性变迁

目的了解细菌性脑膜炎致病菌的分布特点以及耐药谱的变化。方法对1996—2004年川北医学院附属医院收治的细菌性脑膜炎病例进行脑脊液和血培养，并对致病菌进行药敏试验。结果从316例患者的276份脑脊液和269份血标本中共分离出62株致病菌。葡萄球菌最多占30．6％（19／62），其次为大肠埃希菌占14．5％（9／62）、脑膜炎奈瑟菌占11．3％（7／62）和B组链球菌占9．7％（6／62）。葡萄球菌对青霉素的耐药率高于83．3％，对苯唑西林、头孢唑啉的耐药也逐渐升高。肠杆菌科细菌对氨苄西林的耐药率高达87．5％以上，且对第三代头孢菌素、左氧氟沙星的耐药呈逐年增高趋势。结论葡萄球菌、肠杆菌科细菌、脑膜炎奈瑟菌是主要致病菌。细菌耐药性普遍增加。     

2006～2010年湖北省流行性脑脊髓膜炎病原学和血清学监测分析

目的分析湖北省2006～2010年流行性脑脊髓膜炎(流脑)病原学和血清学监测结果,掌握湖北省流脑的变迁规律。方法对2006～2010年分离的脑膜炎奈瑟菌(Nm)菌株进行生化鉴定、血清学分型和药物敏感性检测,并采用多位点序列分型(MLST)和脉冲场凝胶电泳(PFGE)方法进行分子分型;对所有的脑脊液和血液标本进行Nm种属特异性荧光PCR检测;对健康人群血清,运用血清杀菌试验(SBA)进行C群杀菌力抗体水平测定。结果 2007年湖北省Nm以B群为主,2008～2010年以来C群为优势菌群;对青霉素等6种抗生素均敏感,但对环丙沙星、米诺环素、萘啶酸、复方新诺明4种抗生素出现多重耐药;分子分型结果显示,湖北省B群Nm菌株具有高度的遗传多样性,未发现明显优势的克隆群,C群优势病原株为ST-4821型。RT-PCR检测(988份脑脊液)确诊29例流脑病例,其中C群22例,A群2例、B群5例。C群杀菌力总保护率(抗体滴度≥1︰8)为38.10%。结论湖北省流脑菌株发生了从B群散发到C群流行的变迁,人群对C群Nm的免疫力不足。     

Recent outbreak of meningococcal meningitis--a microbiological study with brief review of literature

Meningococcal disease presents in various clinical forms, most common being meningitis and meningococcemia. A spurt of meningococcal cases was seen in medicine and pediatric wards of Dr. Ram Manohar Lohia Hospital during the recent outbreak from Dec 2005 - June 2006. These had presented either with the classical features of acute purulent meningitis or as fever with rash. The patients were investigated microbiologically for the causative organism which was identified as Neisseria meningitidis in 257 out of 531 cases (48.39%). The classic finding of gram negative diplococci on gram stain remained the mainstay of diagnosis. N. meningitidis isolates from culture were sensitive to all commonly used antibiotics.     

青霉素不敏感的肺炎链球菌pbp2b基因新的变异

目的 调查本地区青霉素不敏感肺炎链球菌(PNSP)的pbp2b基因和氨基酸序列的变异特点.方法 2006年1-12月收集肺炎链球菌临床分离株24株,检测其对青霉素的敏感性,对青霉素不敏感肺炎链球菌的青霉素结合蛋白pbp2b基因进行PCR扩增和测序以及序列比对与生物信息学分析.结果 在13株青霉素不敏感肺炎链球菌[最低抑菌浓度(MIC)≥0.1 mg/L]中,均发生紧邻SSN的Thr445→,Ala替换以及Glu475→Gly、Thr488→Ala/ser的替换;而Glu332→Gly的替换也较常见,存在于12株PNSP(MIC≥0.25 mg/L);另外,在7株青霉素耐药的肺炎链球菌(MIC≥3 mg/L)中,均发生了紧邻KTG之后Ala618→Gly的替换,且这7株菌属于Back's Ⅱ群,与韩国菌株J77的核苷酸及氨基酸序列一致,而菌株14,15,8,11及24的氨基酸序列出现了新的变异,已向GenBank提交序列,获得序列号:EU035970,EU056919,EU056920,EU056921,EUl06886.结论 本地区大多数的青霉素耐药肺炎链球菌pbp2b基因的变异序列高度相似,而青霉素中度敏感肺炎链球菌的基因序列产生新的变异.     

Emergence of W135 meningococcal meningitis in Ghana

Neisseria meningitidis serogroup W135, well known for a long time as a cause of isolated cases of meningococcal meningitis, has recently increasingly been associated with disease outbreaks of considerable magnitude. Burkina Faso was hit by W135 epidemics in the dry seasons of 2002-2004, but only four W135 meningitis cases were recorded between February 2003 and March 2004 in adjoining Ghana. This reconfirms previous findings that bottlenecks exist in the spreading of new epidemic N. meningitidis clones within the meningitis belt of sub-Saharan Africa. Of the four Ghanaian W135 meningitis patients one died and three survived, of whom one had profound neurosensory hearing loss and speech impairment. All four disease isolates were sensitive to penicillin G, chloramphenicol, ciprofloxacin and cefotaxime and had the multi-locus sequence type (ST) 11, which is the major ST of the ET-37 clonal complex. Pulsed-field gel electrophoresis (PFGE) profiles of the Ghanaian disease isolates and recent epidemic isolates from Burkina Faso were largely identical. We conducted meningococcal colonization surveys in the home communities of three of the patients and in the Kassena Nankana District located at the border to Burkina Faso. W135 carriage rates ranged between 0% and 17.5%. When three consecutive surveys were conducted in the patient community with the highest carrier rate, persistence of W135 colonization over a period of 1 year was observed. Differences in PFGE profiles of carrier isolates taken at different times in the same patient community were indicative of rapid microevolution of the W135 bacteria, emphasizing the need for innovative fine typing methods to reveal the relationship between W135 isolates.     

Association of virulence of Neisseria meningitidis with transparent colony type and low-molecular-weight outer membrane proteins

To assess the factors that might be associated with the virulence of Neisseria meningitidis, isolates from the blood or cerebrospinal fluid of patients with meningococcal disease and meningococcal isolates from the nasopharynx of asymptomatic carriers were compared with regard to opacity or transparency of colonies. Neisseria meningitidis isolated from patients with meningitis and septicemia grew in predominantly transparent colonies, whereas meningococci isolated from asymptomatic carriers generally formed opaque or a mixture of opaque and transparent colonies. Piliated meningococci from opaque colonies attached to human mucosal cells in significantly greater numbers than did piliated meningococci from transparent colonies of the same isolate. Meningococci from transparent colonies were more resistant to killing by normal human serum than were meningococci from isogenic opaque colonies. Disease-associated isolates that formed transparent colonies contained one or more heat-modifiable outer membrane proteins of molecular weight 26,000-32,000 which were not found in some isogenic clones that formed opaque colonies. Transparency of meningococcal colonies may be an important marker for factors that mediate meningococcal virulence.     

Primary meningococcal pneumonia.

Three cases of pneumonia caused by Neisseria meningitidis group Y are reported. From the results of these cases, the following conclusions were made. N. meningitidis probably can cause serious infection without preceding blood stream invasion. Primary meningococcal pneumonia is not rare; it has no distinctive clinical presentation; and it may not be recognized by routine expectorated sputum cultures. In addition, it may be associated with recent influenzal and adenoviral infections. Lastly, meningococci of the serogroup Y are capable of causing serious disease. Antimicrobial susceptibility studies showed that all three group Y isolates were sensitive to sulfadiazine and rifampin as well as to penicillin, ampicillin, erythromycin, and chloramphenicol.     

Intercontinental spread of a multiresistant clone of serotype 23F Streptococcus pneumoniae.

Isolates of serotype 23F Streptococcus pneumoniae with high levels of resistance of penicillin have been commonly recovered in Spain for more than a decade. Recently penicillin-resistant serotype 23F S. pneumoniae strains were also isolated from children attending a day-care center in Cleveland. A number of Spanish and Cleveland isolates were compared by electrophoretic analysis of penicillin-binding protein (PBP) profiles and DNA restriction endonuclease cleavage profiles of the PBP 2X and 2B genes amplified with the polymerase chain reaction and by multilocus enzyme electrophoresis. All strains were identical by these criteria. The findings demonstrate that the Spanish and Cleveland isolates are clonally related and suggest that this antibiotic resistant clone of serotype 23F S. pneumoniae has spread intercontinentally from Spain to the United States.