Antimicrobial defense mechanisms in the horseshoe crab, Limulus polyphemus: preliminary observations with heat-derived extracts of Limulus amoebocyte lysate.

Heat-derived (60°C) extracts of Limulus amoebocyte lysate (LAL) were found to contain potent “broad-spectrum” antimicrobial activity. Additional heating of the LAL extracts to 100°C for 30 min completely inactivated the antimicrobial activity and served as a control. Antimicrobial activity was observed over a temperature range of 0° to 37°C (higher temperatures not tested) with greatest activity at 37°C. Antimicrobial activity of LAL extracts was variable when tested against Gram-negative bacteria of the family Enterobacteriaceae. A twofold concentration of the extracts resulted in a significant decrease in antimicrobial effectiveness. Dialysis of single- and double-strength LAL extracts against deionized water produced a marked and significant enhancement of antimicrobial activity against both resistant and sensitive species, confirming the presence of a dialyzable inhibitor(s). Dialyzed LAL extracts were active against 13 of 14 species of Enterobacteriaceae tested. Two strains of Pseudomonas aeruginosa were susceptible as were two of three Gram-positive cocci tested. Highly sensitive bacterial species were rapidly killed with a greater than 90% reduction in viable counts occurring within the first 30 min of reaction time. Dialyzed LAL extracts also possessed considerable antifungal activity. The role of the Limulus polyphemus amoebocyte in defense against microbial invasion and dissemination is discussed.     

不同抗凝人血浆凝固酶检测的探讨

目的 了解3种不同抗凝人血浆检测血浆凝固酶的可行性及观察时间对结果的影响.方法 用3种不同抗凝人血浆及以不同菌液浓度作试管法凝固酶试验.结果 EDTA-K2抗凝血浆出现阳性慢,凝块大多较小,24 h内稳定性较好;枸橼酸钠抗凝血浆出现结果介于EDTA-K2、肝素抗凝血浆之间,结果最不稳定;肝素抗凝血浆出现阳性最快,但不够稳定;菌液浓度对出现阳性的早晚无影响.结论 3种抗凝人血浆在试管法凝固酶测定中使用时,出现阳性快慢不受菌液浓度影响,随时间延长溶解现象可能会增加,应掌握结果观察时间,以降低假阴性.     

Wall-associated processing of extracellular enzymes of Staphylococcus simulans biovar staphylolyticus

Staphylococcus simulans biovar staphylolyticus produces a staphylolytic glycylglycine endopeptidase (lysostaphin) and a micrococcolytic endo-β-N-acetylglucosaminidase (hexosaminidase) as proenzymes that are proteolytically processed through multiple intermediates to their mature forms by an extracellular sulfhydryl protease. Analysis of protease production by immunoblots using antiserum prepared against purified protease and by renaturing activity gels using gelatin as the substrate has revealed that the lysostaphin-processing protease also is produced as a proenzyme, which appears to be autocatalytically processed. Very little proprotease could be detected in supernatants from cultures of S. simulans biovar staphylolyticus, which suggested that the protein was being processed before it was released to the culture medium. Analysis of wall-associated proteins revealed that processing of proprotease occurred primarily in the cell wall. Furthermore, processing of prolysostaphin and prohexosaminidase also occurred in the cell wall matrix.     

Drug‐Resistant Human Staphylococcus Aureus in Sanctuary Apes Pose a Threat to Endangered Wild Ape Populations

Reintroduction of sanctuary apes to natural habitat is considered an important tool for conservation; however, reintroduction has the potential to endanger resident wild apes through the introduction of human pathogens. We found a high prevalence of drug‐resistant, human‐associated lineages of Staphylococcus aureus in sanctuary chimpanzees (Pan troglodytes) from Zambia and Uganda. This pathogen is associated with skin and soft tissue diseases and severe invasive infections (i.e. pneumonia and septicemia). Colonization by this bacterium is difficult to clear due to frequent recolonization. In addition to its pathogenic potential, human‐related S. aureus can serve as an indicator organism for the transmission of other potential pathogens like pneumococci or mycobacteria. Plans to reintroduce sanctuary apes should be reevaluated in light of the high risk of introducing human‐adapted S. aureus into wild ape populations where treatment is impossible. Am. J. Primatol. 74:1071‐1075, 2012. © 2012 Wiley Periodicals, Inc.     

Tracing the transition of methicillin resistance in sub-populations of Staphylococcus aureus, using SELDI-TOF Mass Spectrometry and Artificial Neural Network Analysis

Strains (n = 99) of Staphylococcus aureus isolated from a large number of clinical sources and tested for methicillin sensitivity were analysed by MALDI-TOF-MS using the Weak Cation Exchange (CM10) ProteinChip Array (designated SELDI-TOF-MS). The profile data generated was analysed using Artificial Neural Network (ANN) Analysis modelling techniques. Seven key ions identified by the ANNs that were predictive of MRSA and MSSA were validated by incorporation into a model. This model exhibited an area under the ROC curve value of 0.9147 indicating the potential application of this approach for rapidly characterising MRSA and MSSA isolates. Nearly all strains (n = 97) were correctly assigned to the correct group, with only two aberrant MSSA strains being misclassified. However, approximately 21% of the strains appeared to be in a process of transition as resistance to methicillin was being acquired.     

The role of infectious agents in sudden infant death syndrome

Abstract Epidemiological factors associated with susceptibility to respiratory infections are similar to those associated with Sudden Infant Death Syndrome. Here we review the evidence that respiratory pathogens might be involved in some cases of Sudden Infact Death Syndrome in the context of factors identified in epidemiological studies of cot deaths: the age range affected; mother's smoking; respiratory viral infections; immunisation status. Both laboratory and epidimiological evidence suggests that vulnerability of infants to infectious agents depends on interactions between genetic, developmental and environmental factors that contribute to colonisation by microorganisms, the inflammatory and specific immune responses and the infants' physiological responses to inflammatory mediators. A model is proposed to explain how microorganisms might trigger a series of events resulting in some of these unexpected deaths and discusses how the present recommendations regarding child care practices might help reduce the numbers of Sudden Infant Death Syndrome cases associated with infectious agents.     

Relationship between antibody productivity by activated human lymph node lymphocytes from lung cancer patients and lymphocyte subsets

Regional lymph node lymphocytes from five patients with primary lung cancer were analyzed for subset composition, and exposed in vitro to the polyclonal human B cell mitogen Staphylococcus aureus Cowan I (SACI) or the murine B cell mitogen lipopolysaccharide (LPS) and then fused with mouse myeloma cells for investigation at the clonal level of their antibody (Ab) production and its statistical relation to the original subset composition. No correlation was found between the proportion of CD19+, CD23+, or CD3+ cells in the lymphocyte sample prior to its exposure to either SACI or LPS, and the Ab production efficiency, defined as the ratio of the number of Ab producing wells to the total number of proliferating wells. For lymphocytes exposed to LPS, however, a strong correlation (r = 0.931, p = 0.02) was observed between the Ab production efficiency and the ratio of CD8+ to CD3+ cells (CD8/CD3) in the original sample at least within the ranges studied (CD8/CD3 = 0.216–0.288). For those exposed to SACI, no correlation was found between the Ab production efficiency and the CD8/CD3 ratio (r = 0.881, p = 0.12) or the proportion of CD8+ cells (r = 0.808, p = 0.19) in the original sample. These results suggest that the repertoire of B cells responsive to LPS is different at least in part from the repertoire responsive to SACI and that the ratio CD8/CD3 could serve as a practical predictor for Ab production by human lymphocytes stimulated with LPS. This revised version was published online in July 2006 with corrections to the Cover Date.     

Expression of the Cellulase (FI-CMCase) Gene of Aspergillus aculeatus in Escherichia coli

FI-CMCase cDNA of Aspergillus aculeatus was expressed in Escherichia coli by using the tac promoter of E. coli. Transformants of E. coli harboring a plasmid pHEM06 containing mature form FI-CMCase cDNA produced FI-CMCase in the cytoplasm of the cells. The enzyme from E. coli cells was purified to yield 56% and it was immunological identical to that of FI-CMCase purified from A. aculeatus.     

深圳市金黄色葡萄球菌耐药性分析及分子分型

目的 了解深圳市金黄色葡萄球菌的耐药性特点及分子分型特征。方法 收集2012年来自深圳市7所医院的428株金黄色葡萄球菌,以琼脂稀释法测定其对12种抗菌药物的最低抑菌浓度（MIC）,采用聚合酶链式反应（PCR）检测杀白细胞毒素（PVL）,并对携带PVL基因的菌株进行多位点基因序列分型（MLST）。结果 428株金黄色葡萄球菌中耐甲氧西林金黄色葡萄球菌（MRSA）116株（26.2%）,甲氧西林敏感金黄色葡萄球菌（MSSA）312株（73.8%）。12种抗菌药物中,该菌对青霉素和红霉素的耐药率最高,分别为88.8%和44.2%;未发现替考拉宁、利奈唑胺和万古霉素的耐药株。MRSA对青霉素和环丙沙星的耐药率显著高于MSSA。428株金黄色葡萄球菌中,60株（14.02%）携带PVL基因。MLST分型结果显示共有14种已知序列型和4种新的序列型,其中ST59和ST338最多,分别为16株和12株。结论 深圳地区金黄色葡萄球菌MRSA检出率以及对多种抗菌药物的耐药率均低于全国平均水平,PVL基因阳性率处于中等水平;存在多种ST分型,以ST59和ST338多见,具有遗传多样性和独特的遗传背景。