Spread of a multiresistant strain of Pseudomonas aeruginosa in an adult cystic fibrosis clinic

We initiated a prospective surveillance study to investigate possible Pseudomonas aeruginosa cross-infection in our cystic fibrosis centre. We characterised isolates by pyocin typing and pulsed-field gel electrophoresis. 22 (14%) of 154 patients with chronic P aeruginosa had isolates with similar and new pyocin and pulsed-field gel electrophoresis types. The shared isolates showed unusual phenotypic features: they were non-pigmented, non-motile, and resistant to a number of antipseudomonal antibiotics. Cross-infection by a multiresistant P aeruginosa strain has therefore occurred in patients attending our cystic fibrosis centre. We recommend microbiological surveillance in other cystic fibrosis centres.     

Isolation of Salmonella typhi from standard whole-blood culture vs blood-clot cultures

The use of 10% oxgall and bile broth medium, both supplemented with freshly prepared 100 u/ml streptokinase, for isolating Salmonella typhi by clot culture technique was evaluated and compared against whole blood culture systems (3 ml blood in 9 ml media and 8 ml blood in 72 ml media). These gave a 1:4 and 1:10 blood to medium ratio, respectively. Clot cultures in 10% oxgall (CLOX) gave a 57% positive isolation rate for S. typhi. A similar result was obtained from clot cultures in bile broth medium (CLBB). A total of 184 samples identified as positive for S. typhi were tested. There was no significant difference between the use of 10% oxgall or bile broth medium when used for clot culture. The whole blood culture systems still showed a significantly better rate of isolation than the clot culture methods.     

一株牛源约翰逊不动杆菌的分离鉴定

目的分离并鉴定1株致2018年7月四川省某肉牛场肉牛患呼吸道疾病并死亡的约翰逊不动杆菌。方法采集发病牛鼻腔拭子并从中分离得到一株优势菌株,对其进行形态学鉴定、生化鉴定、测定16s rRNA基因序列,用MEGA-X软件进行同源性分析、构建进化树,并进行药敏检测。结果分离菌为革兰染色阴性短杆菌,生化特性与约翰逊不动杆菌相符合,16S rRNA序列与GenBank中约翰逊不动杆菌株的同源性均达99%,因此将分离菌确定为约翰逊不动杆菌,并命名为ZZCNC-7B。8只SPF级昆明小鼠用1.4×10⁸ CFU/ml的ZZCNC-7B菌液腹腔注射(0.2 ml/只)后出现精神沉郁、腹式呼吸、眼部出现黏性分泌物、眼睑粘连、畏寒抱团等症状,有6只小鼠在16~36 h内死亡,另2只小鼠出现相同的症状但仍存活。剖检死亡小鼠,大体观察肺、肾充血肿大;肝、脾淤血肿大,肠道积气积液;组织学观察肺充血、出血,肝淤血,脾淤血、出血,肾小管坏死等病变。药敏试验显示,分离菌对四环素类药物四环素和磺胺类药物磺胺异恶唑耐药,对氨苄西林、亚胺培南、左氧氟沙星以及庆大霉素等药物均敏感。结论病牛分离菌为约翰逊不动杆菌,对小鼠具有较强的致病性和致死性,可引起肉牛呼吸道感染,甚至导致肉牛死亡,应引起高度重视。     

Isolation of a Plasmodium vivax refractory Anopheles culicifacies strain from India

Anopheles culicifaciessensu lato comprises five sibling species. We report the isolation of an An. culicifacies species B strain which is completely refractory to Plasmodium vivax sporogonic development and partially refractory to P. falciparum. Parasite development in this strain is arrested by a melanotic encapsulation mechanism in the mid-gut. We compare the infectivity of this refractory strain and four other species B strains from different epidemiological zones of India with P. vivax in the laboratory.     

Outbreak of a multiresistant Klebsiella pneumoniae strain in an intensive care unit: antibiotic use as risk factor for colonization and infection.

An observational study was undertaken to describe a nosocomial outbreak caused by multiresistant Klebsiella pneumoniae (MRKP). Ten patients in the pediatric intensive care unit (ICU) at a hospital in Madrid were colonized by or infected with MRKP from October 1997 to April 1998. Thirty-two patients with MRKP-negative surveillance cultures who were admitted to the ICU during the outbreak period were selected as control patients. Random amplified polymorphic DNA analysis of MRKP isolates revealed patterns that were indistinguishable from each other. After identification of colonized patients by surveillance cultures and implementation of standard and contact precautions, the outbreak was controlled. An age <12 weeks (odds ratio [OR], 13.1) and previous treatment with third-generation cephalosporins and aminoglycosides (OR, 31.2) were independently associated with MRKP colonization and/or infection. Individual exposure to antibiotics, irrespective of other clinical determinants, is a risk factor for MRKP acquisition. Screening high-risk patients during outbreaks and reducing the use of third-generation cephalosporins and aminoglycosides contribute to the control of these epidemics.     

HIV毒株分离及体外感染实验研究

目的 从艾滋病病毒(HIV)感染者(万某)分离获得HIV毒株，应用此毒株在体外攻击与HIV感染者长期无保护性行为未引发感染者(张某)及健康人的淋巴细胞，检测病毒感染细胞情况，研究抗感染保护的机制。方法 采用RT测定法和P24抗原检测法。将HIV感染者淋巴细胞与健康人淋巴细胞共培养，并将获得的HIV毒株体外攻击张某及健康人的淋巴细胞，分别观察细胞病变并检测P24抗原及逆转录酶的活性。结果 从万某血中分离获得了HIV—1毒株，连续8周显微镜观察，从第2周开始可见HIV特有的细胞病变，逆转录醇的活性检测和P24抗原检测结果从第2周为阳性，说明病毒分离成功。健康人淋巴细胞自HIV—l感染后2周开始，显微镜可观察到HIV—l持有的细胞病变，逆转录酶的活性检测和P24抗原检测结果均为阳性，表明HIV侵入。张某的淋巴细胞在HIV感染后显微镜下观察，始终未见特有的细胞病变，逆转录酶的活性检测和P24抗原检测结果均为阴性，表明HIV病毒未侵入细胞。结论 分离的毒株可以感染健康人淋巴细胞，说明病毒本身无变异；病毒不能侵入张某的淋巴细胞，可能是其淋巴细胞表面HIV—l受体或辅受体的基因或功能发生突变，导致病毒无法侵入机体。     

Lack of immune response to the Vi component of a Vi-positive variant of the Salmonella typhi live oral vaccine strain Ty21a in human studies

New typhoid vaccines have been sought to replace the reactogenic parenteral whole cell vaccines. Both Ty21a, a live oral attenuated Vi-negative Salmonella typhi vaccine strain, and parenteral Vi polysaccharide vaccine are safe and efficacious in field trials. To achieve potentially greater protective efficacy, a derivative of Ty21a that expresses Vi polysaccharide was prepared and its safety and immunogenicity assessed in 27 adult volunteers. The volunteers received either one dose of 5 x 10(5), 5 x 10(7), or 5 x 10(9) cfu or three doses of 5 x 10(9) cfu of lyophilized vaccine and were observed for adverse effects on a research isolation ward. The vaccine was well tolerated; however, at the highest dose, 13% of volunteers had mild diarrhea. Serial blood cultures were negative for the vaccine strain. Vaccine was shed in the stool of most volunteers at the higher doses for 1-4 days. No serum antibodies to Vi, circulating cells secreting antibody to Vi, or jejunal fluid antibodies to Vi were detected in any volunteer.     

G2 as an emerging rotavirus strain in pediatric gastroenteritis in southern Italy

Background  

Human rotaviruses (HRVs) represent a major cause of acute gastroenteritis in children worldwide. It is estimated that they are responsible for a large number of diarrhea-associated hospitalizations in childhood each year. In Italy, limited data are available on the patterns of distribution of HRV G and P types. We report here the results of 2 years of rotavirus strain surveillance among children with severe gastroenteritis diagnosed in the town of Portici, Campania, southern Italy.