单克隆抗体对变链球菌粘附的影响

分别用抗ＯＭＺ１７６菌（ｄ血清型）和抗ＭＴ６Ｒ菌（ｃ血清型）表面蛋白抗原２２０ＫＤ和１８５ＫＯ分子量的单克隆抗体（ＭｃＡｂ）对血清型变链球菌ｃ、ｄ作用后，通后３Ｈ核素标记测试细菌的粘附性。结果显示：抗２２０ＫＤ、抗１８５ＫＤ表面蛋白抗原的ＭｃＡｂｓ对相应血清型的变链球菌的粘附均呈现明显的抑制作用，两种ＭｃＡｂｓ对不相应血清型变链球茵的粘附也有一定的抑制作用。因而认为ＭｃＡｂ通过局部被动免疫抗粘附原理对变链球菌粘附具有抑制作用。     

变形链球菌在父子间传播的研究

目的　本实验应用随机引物聚合酶链反应法 (AP PCR)对父子间变链的传播进行研究 ,以期为龋病预防提供新思路和理论依据。方法　随机选取中国沈阳一个幼儿园 10名 3～ 5岁的儿童及其父亲作为研究对象 ,取父亲非刺激性全唾液并刮取儿童牙菌斑 ,进行细菌培养 ,用酚 -氯仿法抽提细菌DNA ,进行PCR反应 ,电泳。结果　儿童共分离出 16个基因型 ,3个与父亲的一致 ,占 18.8%。结论　在中国家庭父子间存在变链传播     

孕早期血糖水平与孕晚期B族链球菌带菌状况相关性分析

目的研究孕妇孕早期(孕8~12周)血糖水平与孕晚期(35~37周)B族链球菌(group B Streptococcus,GBS)检出率的相关性。方法收集2014年1月~2017年6月在本院产科就诊并建立产前保健档案的孕妇资料,收取在孕8~12周进行空腹血糖检测及在孕35~37周进行实时荧光定量-聚合酶链反应(polymerase chain reaction,PCR)GBS DNA检测的孕妇1240例,对其血糖水平与GBS阳性检出率进行统计分析。结果 GBS检测阳性孕妇307例,血糖均值为(4.55±0.40)mmol/L;阴性孕妇933例,血糖均值为(4.69±0.57)mmol/L,两组血糖水平差异有统计学意义(t=3.990,P=0.000)。按孕妇空腹血糖范围分为≤4.50 mmol/L、(4.51~5.10)mmol/L和≥5.11 mmol/L三组,其GBS检出阳性率分别为29.17%、23.37%和15.58%,差异有统计学意义(P0.05)。结论孕早期血糖水平与孕晚期GBS检出率呈明显负相关性,孕早期血糖水平较低的孕妇应警惕孕后期GBS感染。     

Genetic diversity and exotoxin A production of group A streptococci causing sepsis

The M protein and streptococcus pyrogenic exotoxin (SPE A) are important virulence factors in group A streptococci (GAS) infections. The emm types of GAS strains isolated from patients with sepsis were determined by sequencing the 5' N-terminus of the emm gene, encoding the M protein, and clonality analysis using pulsed-field gel electrophoresis. The presence of speA and production of SPE A were also examined. There were no predominant GAS clones. The emm genotypes were variable, and the most common genotype was emm13 (17.9%). The production prevalence of SPE A was 21.4%. The low mortality rate (7.1%) of GAS sepsis might be attributable to the low incidence of virulent strains such as emm1 (10.7%) and emm3 (7.1%), as well as to low production rate of SPE A.     

Microbiological diagnosis of streptococcal pharyngitis: lacunae and their implications

Post-streptococcal sequelae, especially acute rheumatic fever/rheumatic heart disease continue to occur in significant proportions in many parts of the world. Despite several attempts with various intervention strategies, little success has been achieved in the control of acute rheumatic fever/rheumatic heart disease in India. The success of the control programmes depends upon timely primary prophylaxis with benzathine penicillin for which a microbiological confirmation of group A streptococcal pharyngitis is essential. Isolation of beta hemolytic streptococci from throat cultures and their identification as GAS in the laboratory, clinches the microbiological diagnosis while demonstration of a 'significant rise' in antibody titers such as Anti-streptolysin O and Anti-deoxyribonuclease B differentiates it from a group A streptococcal carrier state or pharyngitis of a viral etiology. Despite the easiness with which these can be achieved, many laboratories in India are not equipped to do so. Enhancing bacteriological and serological facilities in laboratories across the country will drastically improve the clinician's ability to diagnose bona fide GAS pharyngitis and help to institute penicillin prophylaxis at the appropriate time. This will go a long way in enhancing the compliance to penicillin prophylaxis which is the cornerstone of any RF/RHD control program.     

Peritonsillar abscess — Do we need anaerobic cover?

Objective

To find out the usability and advantage with regard to the advent of new and more costly antibiotics. In the treatment of Peritonsillar abscess the demonstration of, both aerobic and anaerobic organisms has raised the question of possible need to treat with antibiotics effective against anaerobes. It was in this very context that this study was planned to find out if we still have an economically and easily available antibiotic to treat Peritonsillar abscess.

Conclusions

Injectable penicillin is the drug of choice in PTA as GABHS and staphylococcus aureus coagulase positive are the most common organism associated with this condition. Even where penicillin resistant organism is present, effective management of the abscess is possible if it is drained well and weak hydrogen peroxide gargles are used along with injectable penicillin.     

Rapid identification of beta-hemolytic streptococci by fluorescence in situ hybridization (FISH)

Rapid identification of pathogenic, beta-hemolytic streptococci is important for treatment decisions. We evaluated fluorescence in situ hybridization (FISH) for this purpose using 23 reference strains, 157 clinical isolates, and 80 blood cultures showing streptococci in the Gram stain. With a sensitivity and specificity in excess of 99%, FISH proved to be suitable for rapid identification of beta-hemolytic streptococci in a diagnostic laboratory.     

Immunization with C5a peptidase from either group A or B streptococci enhances clearance of group A streptococci from intranasally infected mice

Group A streptococci (S. pyogenes) are responsible for pharyngitis, impetigo and several more serious diseases. Emergence of toxic shock, and necrotizing fasciitis, associated with this pathogen over the past 10 years, has generated interest in development of a vaccine, which would prevent infections and potential serious complications. The highly conserved C5a peptidase that is expressed on the surface of group A streptococcus and other streptococcal species, associated with human infections, is a prime vaccine candidate. Here, we report construction of an inactive form of the peptidase and test its potential to induce protection in mice from intranasal challenge with either serotype M1 and M49 strains of streptococci. Mice were immunized by subcutaneous administration of recombinant proteins, mixed with Alum and monophosphoryl lipid A (MPL) adjuvants. Control mice were vaccinated with tetanus toxoid in the same adjuvants. Preparations of SCPA protein were highly immunogenic in mice. Antibody directed against protein from either group A (SCPAw) or group B (SCPBw) streptococci neutralized activity associated with both enzymes. Streptococci were cleared from the oral-nasal mucosa of mice immunized with vaccine protein more rapidly than those immunized with tetanus toxoid. Moreover, immunization with either protein enhanced clearance of group A streptococci from the lung. These results suggest that parenteral vaccination with SCPBw protein will provide protection against infection by either group A or B streptococci.     

Validation of use of a traditional remedy from Bridelia grandis (Pierre ex Hutch) stem bark against oral Streptococci

Aim of the study

Bridelia grandis (Pierre ex Hutch) (Euphorbiaceae) is a medicinal plant traditionally used in Cameroon by pygmies Baka as a remedy for oral cavity affection. Bioassay-guided stem bark extracts were investigated for their in vitro antimicrobial properties as well as their phytochemical constituents.

Materials and methods

The first extraction was carried out according to the traditional use. Further extractions were carried out with solvents of different polarity such as methanol (MeOH), ethyl acetate (EtOAc) and mixtures of MeOH–H₂O. The antimicrobial activity of the extracts against oral Streptococci was evaluated on the basis of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by the macrodilution method; the bacterial surface hydrophobicity was also evaluated.

Results

Water, methanol and mixtures methanol–water extracts, exhibited antibacterial activity with MIC between 0.5 and 2 mg/ml justifying the traditional use of Bridelia grandis stem bark for oral cavity affection. Preliminary phytochemical analysis was performed on the most active extract (methanol) using appropriate tests and well established analytical screening methods, such as TLC and RP-HPLC/DAD.

Conclusions

The data obtained indicate that tannins constitute the chemical family responsible for the biological activity.     

A study of risk factors of vaginal colonization with group B streptococci in pregnancy

Two hundred pregnant women were screened for vaginal Group B Streptococci carriage just before delivery. Fifty non-pregnant women were also examined. Vaginal colonization rate of pregnant women and of non-pregnant women was identical (12% in both groups). None of the personal and social characteristics investigated (age, profession, residence, marital status and education) were associated with higher or lower colonization rates. However the influence of the number of previous pregnancies proved to be significant, as pregnant women with 2 or more previous pregnancies tended to be more frequently colonized than primigravidae or secundigravidae women. These findings are discussed in relation to the possible reservoir of the microorganisms and the route of infection.