幽门螺杆菌对克拉霉素耐药的分子机制研究

目的：研究幽门螺杆菌（Hp)对克拉霉素耐的分子机制。方法：用E－test进行克拉霉素药敏试验,选取治疗前敏感、治疗后耐药的配对菌株及原发耐药Hp菌株进行研究;应用随机扩增多态性DNA（RAPD）分析,确定治疗前后菌株的同一性;用PCR－限制性片段长度多态性（RFLP）分析探讨克拉霉素耐药机制。结果9株克拉霉素耐药菌23SrRNA基因功能区V PCR扩增片段,8株被BsaI酶切,9株均未被BbsI酶切,提示8株在2144位点有A→G突变。结论上海地区大多数克拉霉素耐药Hp菌株存在23SrRNA基因功能区V2144位点A→G突变。     

幽门螺杆菌对克拉霉素耐药机制的研究进展

幽门螺杆菌(Hp)感染是胃炎、消化性溃疡的主要致病因素,并与胃癌、胃黏膜相关淋巴样组织淋巴瘤的发生密切相关。Hp耐药现象日趋严重,以克拉霉素为主,Hp的23S rRNA V区发生点突变是耐克拉霉素的主要机制。此文就Hp对克拉霉素的耐药作一综述。     

淮南地区幽门螺杆菌对克拉霉素耐药性及其耐药分子机制的研究

目的探讨淮南地区幽门螺杆菌(Helimbacter pylori,Hp)对克拉霉素耐药情况及其耐药分子机制。方法用E-test和琼脂稀释法进行克拉霉素药敏试验,提取Hp基因组DNA,PCR扩增Hp 23S rRNA基因,并用PCR-限制性片段长度多态性(RFLP)分析克拉霉素耐药机制。结果淮南地区克拉霉素耐药率为9.15%(27/141),克拉霉素耐药与性别、年龄无关。PCR从Hp基因组DNA中扩增出425bp的Hp 23S rRNA基因,PCR-RFLP检测,27株耐药菌株均可被Bbsl酶切成332、93bp两个片段,未检测到被BsaⅠ酶切的耐药菌株。结论淮南地区克拉霉素耐药率较高,耐药菌株存在23S rRNA基因功能区V2143位点A-G突变。     

39株对克拉霉素耐药的结核分枝杆菌临床分离株23SrRNA检测结果分析

目的 分析对克拉霉素耐药的结核分枝杆菌临床分离株23S rRNA的A2058位点的变化。 方法 选择我院菌株库的结核分枝杆菌临床分离株64株,其中10株为对全部抗结核药物敏感的结核分枝杆菌临床分离株;14株为单耐克拉霉素的结核分枝杆菌临床分离株;15株为耐多药,同时耐克拉霉素的结核分枝杆菌临床分离株;15株为耐多药,同时对克拉霉素敏感的结核分枝杆菌临床分离株;10株为广泛耐药菌株,同时对克拉霉素耐药的结核分枝杆菌临床分离株;此外,还有结核分枝杆菌标准株H37Rv 1株。对结核分枝杆菌23S rRNA行PCR检测和测序。 结果 经检测,H37Rv标准株没有A2058突变,只有1株广泛耐药临床分离株检测有A2058A-G的突变,其他临床分离株均没有突变,在耐克拉霉素的结核分枝杆菌临床分离株中占2.56%（1/39）,在广泛耐药结核分枝杆菌临床分离株中占1/10。 结论 结核分枝杆菌临床分离株对克拉霉素耐药的机制中, A2058突变可能不是产生对克拉霉素耐药的主要机制。结核分枝杆菌产生对克拉霉素耐药的机制有待进一步研究。     

幽门螺杆菌克拉霉素耐药的研究现状

幽门螺杆菌(Hp)与消化系统多种疾病密切相关,根除Hp治疗可改善相关疾病的转归及预后.Hp对克拉霉素耐药严重影响根治疗效,而根除治疗失败后克拉霉素耐药率明显增加,Hp对克拉霉素耐药与23S rRNA V区点突变有关.根据耐药检测指导用药可明显提高根除率.     

结核分枝杆菌环丝氨酸药物敏感性及耐药机制研究

目的 检测耐多药结核病(MDR-TB)临床分离株的环丝氨酸最低抑菌浓度(MIC),并从基因水平进行环丝氨酸耐药机制的研究,为环丝氨酸的快速耐药测定提供理论依据。方法 采用Middlebrook 7H9液体培养基,在96孔板中对140株MDR-TB和37株敏感结核分枝杆菌(MTB)临床分离株进行环丝氨酸药敏试验,筛选出对环丝氨酸耐药及敏感的菌株,再对Ald、Alr、ddlA基因进行突变位点及基因表达量的分析。结果 MDR-TB对环丝氨酸的耐药率仅为4.28%,初步将MIC≥32 μg/mL的结核分枝杆菌菌株判定为对环丝氨酸耐药;Ald、Alr、ddlA基因位点突变与结核分枝杆菌对环丝氨酸耐药无明显相关性,环丝氨酸耐药菌株在Alr基因位点处基因表达量明显高于敏感菌株。结论 目前临床的MDR-TB患者对环丝氨酸的耐药率较低,使用环丝氨酸治疗MDR-TB是一种有效的选择。尚未发现明确的环丝氨酸耐药突变位点,但Alr基因的过表达与MTB环丝氨酸耐药高度相关,可能是其耐药的新机制。     

重视非结核分枝杆菌感染的实验诊断

由于艾滋病（AIDS）患者增加,肺部非结核分枝杆菌病（NTM）和非结核分枝杆菌（MOTF）感染已日益严重。我国MOTT感染常为速生长分枝杆菌（脓肿、龟分枝杆菌和偶然分枝杆菌）、鸟胞内分枝杆菌、堪萨斯分枝杆菌、戈登分枝杆菌和蟾分枝杆菌等所致。     

结核分枝杆菌耐药机制的研究进展

在人类的传染病中,结核病死亡率最高,每年约有200万人死于结核病;而且估计每年有920万的新发病例,更为严重的是全世界1/3的人口都感染过结核分枝杆菌.据WHO统计,目前全世界耐多药结核患者已占20%,而且这个数字在逐年递增.因此,明确结核分枝杆菌耐药机制不仅能够建立快速、灵敏、准确的检测方法,更重要的是能找到抗结核药物靶点,开发新的抗结核药物,控制结核病疫情,减轻患者的负担与痛苦.     

2016-2021年唐山地区非结核分枝杆菌流行及耐药情况分析

目的 分析唐山地区非结核分枝杆菌(non tuberculosis mycobacterium,NTM)流行及耐药情况,为NTM病的预防及治疗提供依据。方法 收集2016年1月至2021年12月唐山地区NTM人群分离率及药物敏感试验结果,通过趋势检验分析NTM分离率、分析相应菌种构成比及耐药性的趋势变化。结果 从2487例疑似结核病患者痰标本中分离到NTM菌株390株,分离率为15.68%,各年份NTM分离率依次为13.89%、14.12%、14.36%、17.44%、15.69%、18.37%,NTM中前3位的优势菌种为胞内分枝杆菌(62.31%)、堪萨斯分枝杆菌(18.72%)、脓肿分枝杆菌(9.49%)。单一抗NTM药物的耐药率顺位为亚胺西司(IC)(80.3%)>多西环素(DOX)(55.49%)>米诺环素(MNO)(43.35%)>磺胺甲唑(SMZ)(28.32%)>头孢西丁(FOX)(24.86%)>妥布霉素(TOB)(17.92%)>乙胺丁醇(EMB)(14.45%)>利福平(RFP)(10.98%)>阿奇霉素(AZM)(9...     

Pulmonary disease caused by rapidly growing mycobacteria

The rapidly growing mycobacteria (RGM) differ from slow-growing mycobacteria such as Mycobacterium tuberculosis by virtue of their more rapid growth in culture media and their in vitro resistance to standard antituberculosis drugs. The RGM can produce numerous infections including chronic lung disease. The most common causes of pulmonary disease are Mycobacterium abscessus and Mycobacterium fortuitum. This article reviews the management of patients with lung disease caused by RGM.     

Spectrum of disease due to rapidly growing mycobacteria

One hundred twenty-five cases of disease due to rapidly growing mycobacteria were observed over a four-year period. Cutaneous infections accounted for 74 cases (59%). Of these, 40 followed surgical procedures (especially augmentation mammaplasty or median sternotomy), and 34 were due to accidental penetrating trauma. Among the 24 patients with pulmonary disease, the mean age was approximately 60 years, the majority of patients (63%) were women, and most had unilateral noncavitary disease. Other infections included disseminated disease with multiple nodular skin lesions and positive blood cultures, cervical lymphadenitis, keratitis, and endocarditis associated with a prosthetic valve. Infected tissues showed mixed acute and granulomatous inflammation; acid-fast bacilli, when present, occurred in extracellular clumps within microabscesses. Mycobacterium fortuitum and Mycobacterium chelonei were encountered with approximately equal frequency; 80% of isolates of M. chelonei were subspecies abscessus, and 83% of isolates of M. fortuitum were biovariant fortuitum. The outcome in these infections was generally good, although 9% of the patients, including all those with endocarditis, died. Infections due to M. fortuitum and M. chelonei are probably markedly under-diagnosed, and these organisms are capable of causing a wide spectrum of clinical disease.     

Usefulness of picric acid-sauton agar medium for differentiating slowly growing mycobacteria from rapidly growing mycobacteria

A modified Sauton agar medium containing 0.2 % picric acid was useful for differentiating slowly growing mycobacteria from rapidly growing mycobacteria. Slowly growing mycobacteria, with the exception of Mycobacterium simiae, failed to grow on this medium. Rapidly growing mycobacteria, with the exception of Mycobacterium chelonei subsp. chelonei, grew on the medium. These 2 species may therefore be differentiated by the use of the picric acid medium.     

Spectrum of CNS disease caused by rapidly growing mycobacteria

We present a case of a patient with chronic meningoencephalitis caused by Mycobacterium abscessus. We also summarise the clinical features and outcomes of cases of CNS infection caused by rapidly growing mycobacteria that have been described in the literature. Rapidly growing mycobacteria are notorious for causing skin and soft-tissue infections after trauma or surgery, pulmonary disease in patients with cystic fibrosis, and disseminated disease in immunocompromised patients. CNS infection with this organism is extremely rare. Patients usually present with subacute to chronic meningitis, neutrophilic pleocytosis, and have a history of trauma or neurosurgery. The smears are often negative for acid-fast organisms, but may show Gram-positive rods. Treatment requires a long course of two or more antibiotics that have the ability to penetrate the blood-brain barrier, and possibly of steroids as immunomodulatory agents, such as those used in tuberculous meningitis.     

Patterns and distribution of aminoglycoside-acetylating enzymes in rapidly growing mycobacteria

Cell-free extracts from clinical, laboratory, and environmental isolates of Mycobacterium fortuitum, Mycobacterium smegmatis, Mycobacterium phlei, and Mycobacterium vaccae were tested for the presence of aminoglycoside-acetylating enzyme and compared with enzymes from gram-negative organisms. Acetylating activity was detected in all strains examined despite variable levels of aminoglycoside susceptibility. Substrate profiles revealed 2 different patterns of 3-N-acetyltransferase. One pattern exhibited broad substrate specificity including significant activity to fortimicin and was specific for Mycobacterium fortuitum strains, whereas the second pattern showed a much narrower substrate range and was observed for the other 3 environmental species. Both types of enzymes inactivated the antimicrobial activity of drug in vitro. The acetylation reaction of mycobacterial enzyme with radiolabeled acetyl coenzyme A was significantly inhibited by malonyl- (34.7%), propionyl- (21.3%), and butyryl- (12.5%) coenzyme A in the presence of adenosine-5'-triphosphate, whereas no inhibition could be observed for the type enzyme (3-N-acetyltransferase-III) from Pseudomonas aeruginosa suggesting the two enzymes are different. Thus all species of rapidly growing mycobacteria probably contain one of several different types of aminoglycoside acetyltransferases including some isolates and species without a resistance phenotype. The origin and specific function of these enzymes are not known.     

Diagnosis and treatment of infections caused by rapidly growing mycobacteria

Rapidly growing mycobacteria (RGM) are ubiquitous environmental organisms capable of causing a wide variety of infections in humans. The prevalence of RGM infections appears to be increasing, although exact incidence rates are unknown. Although some risk factors for pulmonary RGM infection have been determined, the specific host factors predisposing to disease in the majority of cases are not clear. Significant advances in molecular methods of mycobacterial identification have led to isolation of more varieties, changes in taxonomy, and more rapid and accurate diagnosis of RGM from clinical isolates. Despite significant advances in the field, diagnosing and treating RGM pulmonary infections remain complicated. Current guidelines are based on the most commonly encountered NTM. Their applicability to less frequent RGM isolates has not been definitively established. Treatment often requires multiple antimicrobial agents for prolonged periods of time, with varying degrees of success and significant associated morbidity.     

Infections with rapidly growing mycobacteria: report of 20 cases.

OBJECTIVES: A series of cases infected with rapidly growing mycobacteria was studied to determine the spectrum of disease, antimicrobial susceptibility, treatment, and outcome. METHODS: The cases identified as infections with rapidly growing mycobacteria in Ramathibodi Hospital from January 1993 to December 1999 were retrospectively studied. RESULTS: Most of the cases had no underlying disease. Only two cases were HIV-infected patients. The presenting clinical features were lymphadenitis (seven cases), skin and/or subcutaneous abscess (seven cases), localized eye infection (four cases), pulmonary infection (one case), and chronic otitis media (one case). Four of seven cases with lymphadenitis had Sweet's syndrome, and one had psoriasis as an associated skin manifestation. Anemia was present in five cases, and improved with treatment of the primary disease. The organisms were Mycobacterium chelonae/abscessus group (17 cases) and Mycobacterium fortuitum group (three cases). Susceptibility patterns of the organisms showed susceptibility to amikacin, netilmicin, and imipenem. M. fortuitum group was susceptible to more antibiotics than M. chelonae/abscessus group. The clinical responses corresponded to the antimicrobial susceptibility. Combinations of two or more drugs were used for the medical treatment. Surgical resection was performed where possible, to reduce the load of the organism, especially in cases with very resistant organisms. CONCLUSIONS: Infections with rapidly growing mycobacteria can occur in apparently normal hosts. The clinical syndrome is variable. The pathology is nonspecific. Clinical responses varied, but seemed to correlate with the in vitro susceptibility result. More studies are needed to enable us to deal with this infection effectively.     

Isoelectric focusing patterns of beta-lactamases in the rapidly growing mycobacteria.

beta-lactamases from 259 strains of rapidly growing mycobacteria that included the third biovariant complex of Mycobacterium fortuitum, M. peregrinum, M. abscessus, M. chelonae, the M. chelonae-like organisms (MCLO), and M. smegmatis were analyzed by isoelectric focusing (IEF). All isolates produced acidic beta-lactamases with major band isoelectric points (pIs) between 4.4 and 6.0. Each of the 6 taxonomic groups exhibited 1 or 2 characteristic beta-lactamase IEF patterns. Heterogeneity among IEF patterns was evident in 5 of the 6 groups, however, and was greatest among the third biovariant complex of M. fortuitum. beta-lactamase patterns correlated with previously identified taxonomic subgroups of M. smegmatis and the third biovariant complex of M. fortuitum. beta-lactamase IEF analysis of MCLO strains isolated from two outbreaks demonstrated its possible usefulness for epidemiologic evaluation.