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1.
A study was undertaken to evaluate the therapy of streptococcal pharyngitis. The compliance of 118 patients with beta-hemolytic streptococcal pharyngitis to follow-up was 72%. Of 74 patients checked by means of urine tests 66 took their oral medication. No differences were detected in the clinical and bacteriological results (>98% streptococcal eradication) after the 7th or 10th day of therapy after taking either cephalexin or penicillin.It was concluded that: (a) for effective surveillance and follow-up special attention should be given to the uncooperative segment of the patient population; (b) a seven-day course of penicillin may be satisfactory in the eradication of BHS from the throat; and (c) cephalexin appears to be an effective alternative to penicillin for the treatment of streptococcal pharyngitis.  相似文献   

2.
OBJECTIVE--To evaluate treatment of group A beta haemolytic streptococcal pharyngitis with amoxycillin once daily compared with phenoxymethylpenicillin three or four times a day. DESIGN--Randomised controlled study of consecutive patients presenting with symptoms suggestive of group A beta haemolytic streptococcal pharyngitis in whom culture of a throat swab yielded positive results. SETTING--Five family medicine practices. SUBJECTS--157 patients aged over 3 years who required treatment with antibiotics. MAIN OUTCOME MEASURES--Clinical response, bacteriological response, days at work and school lost, and compliance. RESULTS--During the period of the study 393 patients presented with symptoms suggesting streptococcal pharyngitis; 157 of them had throat swabs that yielded positive results on culture. Eighty two were treated with phenoxymethylpenicillin and 75 with amoxycillin. No difference was observed in the clinical response, days at work and school lost (139 days for 64 patients taking phenoxymethylpenicillin v 100 days for 57 patients taking amoxycillin; p > 0.2), or residual positive cultures after two days (6 (7.3%) v 3 (4%); p > 0.5). A significant difference in the bacteriological response was found after 14 days (5 (6.1%) v 0; p < 0.04) with no positive cultures observed in the amoxycillin group. CONCLUSIONS--These findings support the hypothesis that amoxycillin once daily is as effective as phenoxymethylpenicillin in the treatment of group A beta haemolytic streptococcal pharyngitis.  相似文献   

3.
Acute rheumatic fever is a serious autoimmune sequela of pharyngitis caused by certain group A streptococci. One mechanism applied by streptococcal strains capable of causing acute rheumatic fever is formation of an autoantigenic complex with human collagen IV. In some geographic regions with a high incidence of acute rheumatic fever pharyngeal carriage of group C and group G streptococci prevails. Examination of such strains revealed the presence of M-like surface proteins that bind human collagen. Using a peptide array and recombinant proteins with targeted amino acid substitutions, we could demonstrate that formation of collagen complexes during streptococcal infections depends on an octapeptide motif, which is present in collagen binding M and M-like proteins of different beta-hemolytic streptococcal species. Mice immunized with streptococcal proteins that contain the collagen binding octapeptide motif developed high serum titers of anti-collagen antibodies. In sera of rheumatic fever patients such a collagen autoimmune response was accompanied by specific reactivity against the collagen-binding proteins, linking the observed effect to clinical cases. Taken together, the data demonstrate that the identified octapeptide motif through its action on collagen plays a crucial role in the pathogenesis of rheumatic fever. Eradication of streptococci that express proteins with the collagen binding motif appears advisable for controlling rheumatic fever.  相似文献   

4.
Capture enzyme-linked immunosorbent assays (ELISAs) were developed to detect immunoglobulin G and M antibodies to group A streptococcal (GAS) antigens, streptolysin O, streptokinase, and group A carbohydrate. The sensitivities and the specificities of the IgM capture ELISAs to each GAS antigen were high enough to distinguish the patients with GAS infections (diagnosed as GAS pharyngitis or scarlet fever) from the control groups (healthy people and patients with pharyngitis from whom GAS could not be isolated). On the other hand, the specificities of the IgG capture ELISAs were not very effective in diagnosis of GAS infections. When the capture ELISA and an indirect ELISA detecting IgM antibodies to group A carbohydrate were compared, false-positive reactions due to rheumatoid factor occurred in the indirect ELISA, but did not occur in the capture ELISA. These results indicate that the capture ELISA works better than the indirect ELISA in detecting the IgM antibody, and that the IgM capture ELISA to GAS antigen provides a rapid and highly reliable serodiagnosis for GAS infections employing only a single serum.  相似文献   

5.
Hepatitis A virus (HAV) has emerged as an important public health problem in many countries of the Middle East region and Jordan is no exception. From January 1991 to December 2001, a total of 1015 patients were diagnosed at Al-Battikhi Medical Laboratories. Samples were collected at seventeen private laboratories distributed throughout areas of the Governorate of Amman (capital of Jordan). A significant variation (P=0.03) was obtained between number of HAV cases and year. Seasonal variation in HAV cases was seen throughout the study period with maximal rates in the spring and summer months (P<0.001). The highest incidence rate (9.6/100,000 population) was detected in the year 1993 and the lowest incidence rate (1.1/100,000 population) was found in the year 2001. There was a significant difference (P<0.0001) between number of HAV cases and age group. The highest number of cases 166 (16.4%) was reported for age group 5-14 years and the lowest number of cases 18 (0.02%). Male to female ratio was 1.25: 1. There was no significant sex variation (P=0.28). A significant variation (P=0.006) was observed between number of HAV cases and districts. The present results suggested a link between the age groups, year, month and occurrence of HAV infection. Male to female ratio indicates no significant sex variation.  相似文献   

6.
目的:研究16层螺旋电子计算机断层扫描(CT)三维重建与数字化摄影(DR)平片检查对外伤性肋骨骨折的诊断价值,为临床诊治提供参考。方法:将2017年6月至2018年6月期间于本院接受诊治的82例外伤性肋骨骨折患者作为研究对象,所有患者均接受16层螺旋CT三维重建与DR平片检查,观察并记录患者的骨折发生部位,并比较两种诊断方法对外伤性肋骨骨折诊断的准确率、灵敏度、特异性、阳性预测值、阴性预测值以及漏诊情况。结果:82例外伤性肋骨骨折患者经影像学与临床诊断明确发生骨折179处,多发性骨折发生率为62.20%,单发性骨折发生率为37.80%,骨折肋骨段位中4-10段骨折发生率最高为69.83%,骨折肋骨水平阶段中腋肋骨折发生率最高为59.78%。相较于DR平片,16层螺旋CT三维重建诊断外伤性肋骨骨折的准确率、灵敏度、特异性、阳性预测值、阴性预测值更高,漏诊率更低,差异有统计学意义(P0.05)。结论:相较于DR平片检查,应用16层螺旋CT三维重建检查外伤性肋骨骨折能明显提高临床诊断的准确率、灵敏度和特异性,减少漏诊,可为临床诊治提供更可靠的信息,值得临床推广。  相似文献   

7.
目的探讨儿科肺炎支原体(MP)感染特点,辅助临床医师早期诊断,合理用药。方法测定我院一年来2013例儿科呼吸道疾病患儿的肺炎支原体抗体(IgM)。结果2013例呼吸道感染患儿,检出肺炎支原体抗体(IgM)阳性者769例,占38.2%,769例阳性分别表现为肺炎369例(48%),支气管炎238例(31%),咽炎92例(12%),哮喘70例(9%)。其中,肺炎组与各组相比较,具有统计学意义。MP IgM感染的检出率明显高于其他各组(P〈0.01)。结论MP感染是患儿不可忽视的病原体,检测患儿血清MP抗体能够及早诊断,指导治疗。  相似文献   

8.
Background:Several clinical prediction rules for diagnosing group A streptococcal infection in children with pharyngitis are available. We aimed to compare the diagnostic accuracy of rules-based selective testing strategies in a prospective cohort of children with pharyngitis.Methods:We identified clinical prediction rules through a systematic search of MEDLINE and Embase (1975–2014), which we then validated in a prospective cohort involving French children who presented with pharyngitis during a 1-year period (2010–2011). We diagnosed infection with group A streptococcus using two throat swabs: one obtained for a rapid antigen detection test (StreptAtest, Dectrapharm) and one obtained for culture (reference standard). We validated rules-based selective testing strategies as follows: low risk of group A streptococcal infection, no further testing or antibiotic therapy needed; intermediate risk of infection, rapid antigen detection for all patients and antibiotic therapy for those with a positive test result; and high risk of infection, empiric antibiotic treatment.Results:We identified 8 clinical prediction rules, 6 of which could be prospectively validated. Sensitivity and specificity of rules-based selective testing strategies ranged from 66% (95% confidence interval [CI] 61–72) to 94% (95% CI 92–97) and from 40% (95% CI 35–45) to 88% (95% CI 85–91), respectively. Use of rapid antigen detection testing following the clinical prediction rule ranged from 24% (95% CI 21–27) to 86% (95% CI 84–89). None of the rules-based selective testing strategies achieved our diagnostic accuracy target (sensitivity and specificity > 85%).Interpretation:Rules-based selective testing strategies did not show sufficient diagnostic accuracy in this study population. The relevance of clinical prediction rules for determining which children with pharyngitis should undergo a rapid antigen detection test remains questionable.Pharyngitis accounts for about 6% of visits by children to primary care physicians each year in high-income nations.1 Group A streptococcus is found in 30%–40% of cases of childhood pharyngitis; the remaining cases are considered viral.2 Antibiotic treatment is indicated for group A streptococcal infection to prevent suppurative (e.g., retropharyngeal abscess and quinsy) and nonsuppurative complications (e.g., acute rheumatic fever and rheumatic heart disease) and to reduce the duration of symptoms and the spread of the condition.3 In settings where poststreptococcal diseases have become uncommon, such as Western Europe and North America,4 the public health goal is shifting from preventing complications to minimizing the inappropriate use of antibiotic agents to contain antimicrobial resistance.5 However, 60%–70% of the visits by children with pharyngitis to American primary care physicians result in antibiotic agents being prescribed.68Because signs and symptoms of streptococcal and viral pharyngitis overlap, most experts recommend that the diagnosis of group A streptococcal infection be confirmed by a throat culture or rapid antigen detection test.913 Whereas European guidelines suggest all children with pharyngitis undergo such testing,14 North American guidelines recommend that clinicians select patients on the basis of clinical and epidemiologic grounds.1113 Currently, there is no guidance from the Canadian Medical Association or Canadian Paediatric Society for the management of pharyngitis.Various clinical prediction rules that combine signs and symptoms have been proposed to help clinicians define groups of patients according to the clinical likelihood of group A streptococcal infection.1518 These rules aim to identify patients at low risk in whom the disease can be managed without further testing and without antibiotic treatment, and patients at high risk who could receive empiric antibiotic treatment without testing.16 Clinical prediction rules for pharyngitis have not been sufficiently validated for clinical practice and have never been compared head-to-head in a single pediatric population from a high-income country.18The purpose of our study was to externally validate and directly compare the diagnostic accuracy of relevant rules-based selective testing strategies with original data from a French prospective multicentre cohort of children with pharyngitis. To optimize this validation study, we first conducted a systematic review of existing clinical prediction rules.  相似文献   

9.
The role of host genetic factors in conferring predisposition or protection in infectious diseases has become evident. Infection with group A streptococci causes a wide spectrum of disease ranging from pharyngitis to streptococcal toxic shock syndrome. The release of inflammatory cytokines triggered by streptococcal superantigens has a pivotal role in invasive streptococcal disease. However, individuals infected with the same strain can develop very different manifestations. We report here that the immunogenetics of the host influence the outcome of invasive streptococcal infection, and demonstrate the underlying mechanism for these genetic associations. Specific human leukocyte antigen class II haplotypes conferred strong protection from severe systemic disease, whereas others increased the risk of severe disease. Patients with the DRB1*1501/DQB1*0602 haplotype mounted significantly reduced responses and were less likely to develop severe systemic disease (P < 0.0001). We propose that human leukocyte antigen class II allelic variation contributes to differences in severity of invasive streptococcal infections through their ability to regulate cytokine responses triggered by streptococcal superantigens.  相似文献   

10.
The last comprehensive publication on tuberculosis in Croatia and the earliest impact of war, besides the yearly routine reports, was done in 1996 in Croatian. We were, therefore, interested to explore incidence trends and to highlight the early post-war tuberculosis epidemiological patterns in the next ten years period (1996-2005). A retrospective analysis of epidemiological data on all registered tuberculosis cases in Croatia searching the databases of 21 Croatian Public Health Institutes and the National Tuberculosis Registry was made. During the study period, the total tuberculosis incidence rates in Croatia dropped from 45 to 25.8/100 000 inhabitants. The average highest age-specific rates were recorded in the age group > or = 65 years being in decrease in all age groups. Paediatric cases (0-14 years) represented 4.5% of all cases. Tuberculosis cases among males were recorded in 64% cases, and 83.6% were indigenous population. Tuberculosis was bacteriologically confirmed in 67.7% cases. A low proportion of drug resistance (3.3%) was recorded. During 1985-2005, 56 tuberculosis cases among 242 AIDS cases were reported. Tuberculosis mortality showed a decreasing trend (p < 0.001). However, tuberculosis has still had the highest mortality rates among infectious diseases in Croatia. Despite the War chain of events and tuberculosis programmatic changes, tuberculosis incidence rates in Croatia have been decreasing but they are still far away from national target, incidence rate of 10/100 000 declared in 1998 and much higher than in European Union and Western Europe. Tuberculosis among children, resistance to tuberculosis drugs and HIV prevalence, significant problems in many European countries, have not caused problems in tuberculosis control in Croatia. This favourable epidemiological situation must be kept and improved through strengthened tuberculosis control measures.  相似文献   

11.
BackgroundThe adolescent and young adult (AYA) age group is a bridge between pediatric and adult age groups. The present study describes the epidemiology of cancers in the AYA age group in India.MethodsThe data of primary site cancers in the age group of 15–39 years from the 28 Population Based Cancer Registries (PBCRs') and 58 Hospital Based Cancer Registries under the National Cancer Registry Programme for the reporting year 2012–2016 was analysed.ResultsThe median age adjusted incidence rate (AAR) was 22.2 per 100,000 among males and 29.2 per 100,000 among females. The age-specific incidence rate increased with increasing age in both genders with the highest recorded numbers in the 35–39 age group. The proportion of myeloid leukaemia and non-Hodgkin's lymphoma was highest in the 15–24 age group. Cancers of the breast, thyroid, mouth and tongue constituted the leading sites between 30 and 39 years. There was a significant increase in the incidence among AYA males (APC=0.9) between 1985 and 2015, while a decline in incidence was observed for females, which was not significant (APC=−0.2). The majority of patients had locoregional spread of cancer at the time of diagnosis. The projected number of cancer cases in both genders are expected to increase to 178,617 in 2025.ConclusionCancers in the AYA population are a concern in India. Since AYA oncology appears to be evolving in India, a robust health care system and suitable AYA cancer care policies and programmes are strongly needed to improve disease outcomes and survival.  相似文献   

12.
Abstract

Streptococcus pyogenes is a Gram-positive human bacterial pathogen that causes pharyngitis, tonsillitis, skin infections (impetigo, erysipelis, and other forms of pyoderma), acute rheumatic fever (ARF), scarlet fever (SF), poststreptococcal glomerulonephritis (PSGN), a streptococcal toxic shock syndrome (STSS), and necrotizing fasciitis. These infections are some of the most economically and medically important conditions that affect humans. For example, globally, ARF is the most common cause of pediatric heart disease. It is estimated that in India more than six million school-aged children suffer from rheumatic heart disease (1). In the United States, “sore throat” is the third most common reason for physician office visits and S. pyogenes is recovered from about 30% of children with this complaint (2). It has been estimated that there are 25–35 million cases of streptococcal pharyngitis per year in the United States, and these infections cause 1–2 billion dollars per year in direct health care costs (3,4). Although the continued great morbidity and mortality caused by S. pyogenes in developing nations, the significant health care financial burden attributable to group A streptococci in the United States, and increasing levels of antibiotic resistance (5), have highlighted the need for a fuller understanding of the molecular pathogenesis of streptococcal infection, it has been the relatively recent intercontinental increase in streptococcal disease frequency and severity (6,7) that has resulted in renewed interest in S. pyogenes virulence factors and host-parasite interactions.  相似文献   

13.
目的:探讨单用阴道超声(TVS)、子宫输卵管造影(HSG)、超声子宫水造影(SIS)以及三种方法联合诊断不孕症患者子宫内膜息肉(EP)的临床价值。方法:以206例行宫腔镜联合诊刮或病检的不孕症患者为研究对象,回顾性分析各种检查方法对EP的筛查结果,评价各种检查方法的真实性、可靠性以及预测值。结果:206例不孕症中,共确诊EP患者60例,阳性率29.1%。三种检查方法中,TVS的灵敏度最高(70.0%),特异度最低(73.3%),漏诊率最低(30.0%),误诊率最高(26.7%),正确诊断指数最高(43.3%),阴性似然比最小(0.409),阴性预测值最高(85.6%);SIS检查的灵敏度最低(38.7%),漏诊率最高(61.3%),但是特异性最高(93.3%),误诊率最低(6.7%),阳性似然比最大(4.284),阳性预测值最大(66.6%),正确诊断指数最低(32.0%);HSG检查的上述各项评价指标均介于TVS和SIS之间。TVS和SIS与金标准的符合率低,Kappa值均小于0.4;HSG符合率最高(86.2%),Kappa值0.647。三种检查联合诊断的灵敏度89.3%,漏诊率10.7%,特异度91.4%,误诊率8.6%,正确诊断指数80.7%,阳性似然比10.384,阴性似然比0.117,符合率89.3%,Kappa值0.792,阳性预测值83.3%,阳性预测值94.6%。结论:对于宫腔可能存在内膜息肉的不孕症患者,单一采用阴道超声检查、子宫输卵管造影或超声子宫水造影方法的灵敏度均较低,漏诊率高,与金标准的一致性较差,而三种方法联合用于诊断不孕症患者EP的真实性、可靠性及预测值均较好。  相似文献   

14.
目的 分析与探讨待孕夫妇乙肝表面抗原及乙肝表面抗体检测结果,并研究其对临床孕前检查的影响及评价。方法 随机选取2015‒2017年度在我院进行孕前检查的夫妇2440对(4 880例)为研究对象,按照年度将待孕夫妇分为两组,每组2 440例,两组均加强孕前检查中的乙肝表面抗原(HBsAg)及乙肝表面抗体(HBsAb)的检测。A组为2015年3月‒2016年2月在我院进行乙肝表面抗原及乙肝表面抗体检查的待孕夫妇;B组为2016年3月‒2017年2月在我院进行乙肝表面抗原及乙肝表面抗体检查的待孕夫妇。比较两组待孕夫妇乙肝表面抗原及乙肝表面抗体检测的阳性结果。结果 B组HBsAg阳性率、HBsAb阳性率明显高于A组(6.43% vs 4.63%;62.99% vs 58.44%),差异有统计学意义(P<0.05)。B组、A组男性HBsAg阳性率明显高于同组女性(59.87% vs 40.13%;60.18% vs 39.82%),HBsAb阳性率低于同组女性(46.52% vs 53.48%;47.41% vs 52.59%),差异均有统计学意义(P<0.05)。B组、A组高中及以上学历HBsAg阳性率明显低于同组高中以下学历(38.85% vs 61.95%;38.05% vs 61.15%),高中及以上学历HBsAb阳性率高于同组高中以下学历(53.15% vs 46.84%;51.75% vs 48.25%),差异均有统计学意义(P<0.05)结论 目前夫妇乙肝感染仍处于增高趋势,对于进行孕前检查的待孕夫妇加强乙肝表面抗原及乙肝表面抗体的检测,有助于疾病的早期诊断、干预及治疗,能够减少乙肝传播,可有效降低新生儿乙肝发病率,促进优生优育,提高出生人口整体素质。  相似文献   

15.
OBJECTIVE--To determine the incidence of insulin dependent diabetes mellitus up to the age of 21 in a geographically defined population in England with independent validation of completeness of case ascertainment. DESIGN--Prospective registration of newly diagnosed cases supplemented by centralised hospital discharge records and death certificates. Validation of ascertainment from general practitioners. SETTING--Oxford Regional Health Authority area (population 2.4 million). PATIENTS--All patients with insulin dependent diabetes diagnosed below age 21 during 1985-6 and resident in the region at the time of diagnosis. INTERVENTIONS--None. END POINT--Validation of a method of case ascertainment for assessing temporal variation in incidence of insulin dependent diabetes. MEASUREMENTS AND MAIN RESULTS--The overall yearly incidence of newly diagnosed insulin dependent diabetes mellitus in people under 21 was 15.6 cases/100,000 (95% confidence interval 13.6 to 17.6). Among males the incidence was 16.8 cases (14.0 to 19.7)/100,000 and among females 14.3 cases (11.6 to 17.1)/100,000. The highest incidence, in the 10-14 year age group, was 26.4 (20.9 to 31.8) new cases/100,000 population yearly. Case ascertainment was greater than 95%. CONCLUSIONS--The incidence of insulin dependent diabetes in England is considerably higher than reported from large scale studies. It is consistent with described patterns of geographical variation. The figures provide a baseline for assessing temporal change.  相似文献   

16.
17.
目的:探讨不同浓度丙泊酚联合瑞芬太尼靶控输注喉罩麻醉在小儿短小手术中的临床效果。方法:127例采用小儿短小手术治疗的患儿按丙泊酚给药目标浓度分为A组(2 ng/mL)、B组(3 ng/mL)和C组(4 ng/mL),分别与瑞芬太尼2 ng/mL联合应用靶控输注,行喉罩置入,失败则逐次增加瑞芬太尼剂量0.5 ng/mL直至成功置入。将各组成功率最高时浓度下的患儿分为A1、B1和C1,比较三个亚组不良反应发生情况、以及各时段HR、BIS值和MAP。结果:A组、B组和C组患儿中分别在3 ng/mL、2.5 ng/mL和2 ng/mL时置入成功率最高,满意/可接受比也最高,与其它浓度比较差异有统计学意义(P0.05)。B1组满意/可接受比值高于A1组和C1组,差异有统计学意义(x2=5.189,x2=7.031,P0.05)。不良反应发生率A1组最高,其次是C1组,与B1组比较差异均有统计学意义(P0.05)。组内行方差分析发现,A1组和C1组有较大波动,差异有统计学意义(P0.05),而B1组总体平稳,差异无统计学意义(P0.05)。结论:2.5 ng/mL瑞芬太尼与3 ng/mL丙泊酚靶控输注时喉罩麻醉在小儿短小手术中的应用效果最好,各临床指标较为平稳,不良反应发生率低。  相似文献   

18.
A sample consisting of 2,252 persons among 20,199 Los Angeles civil service employees was observed for the occurrence of heart disease. The first examination measured the prevalence. Based upon the diagnosis of 165 cases of heart disease, the prevalence was 73 per 1,000 persons examined. Two reexaminations, at intervals of 12 to 18 months, of persons with normal heart on the first examination were carried out and 52 additional cases were diagnosed. There were also 13 deaths of heart disease in persons first diagnosed as having normal heart, making a total of 65 "new" cases (36.6 per 1,000) during the 30-month period of observation. An annual estimated heart disease incidence of 15 per 1,000 appears reasonable. Based on 89 deaths, the cardiovascular disease death rate was 11 per 1,000 among persons entering the study with normal heart, and 133 per 1,000 persons diagnosed as having heart disease at entry. The ratio of newly diagnosed cases to deaths of heart disease was 4 to 1.Among men diagnosed as having normal heart there was little difference in death rates whether their jobs were physically strenuous or sedentary. Among the men with heart disease, however, the highest death rates are observed among those employed at sedentary jobs and at light exertion. This may, of course, be an indication of the employee's selection of the job rather than the effect of inactivity. The relative usefulness of minifilm x-ray, electrocardiograms and questioning as to history were considered.  相似文献   

19.
We surveyed Utah general internists (N = 134) regarding their attitudes toward and practices associated with telephone management of upper respiratory tract infections. The questionnaire contained 3 case vignettes--viral upper respiratory tract infection, streptococcal pharyngitis, and acute infectious epiglottitis--and a series of questions were asked about telephone diagnosis, management preferences (clinic versus telephone), and telephone management practices. The 53 respondents (40%) were able to make important diagnostic distinctions about upper respiratory tract infections from a written vignette. As the likelihood of a complicated or serious condition increased, patients would be appropriately triaged for clinical evaluation. Most internists would make a written record of the telephone conversation. Only 1 internist of the 53 would charge for telephone management.  相似文献   

20.
The frequency and severity of streptococcal infections and their sequelae have declined dramatically in the past century, yet the prevalence of streptococcal infections is still high. The reasons for this decline must be intimately related to host resistance, virulence of the agent, and environmental factors, especially crowding. Close examination of these fundamental influences does not reveal any evidence that humans have become less resistant to streptococcal infections, but they react less violently. There is some evidence that the agent may have lost a degree of its virulence. The decline in morbidity and mortality due to streptococcal infections began long before antibiotics, especially penicillin, were available. However, penicillin has proved to be an important factor in prevention of streptococcal infections, especially in rheumatic fever prophylaxis. There are certain indications that repeated streptococcal infections due to similar M types, occurring in young children over the past several decades, have resulted in some degree of immunity as well as the possible evolution of less virulent, but not less infectious, strains of group A streptococci. Also, a decrease in crowding would be expected to result in fewer streptococcal infections. Although there are more people in the world than at any other time in the history of man, urban population density in the western world, at least, is less than in the late 1800s and early 1900s.  相似文献   

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