A single succinic semialdehyde dehydrogenase is involved in 4-hydroxyphenylacetate and 4-aminobutyrate catabolism in Klebsiella pneumoniae M5a1

Abstract Klebsiella pneumoniae M5a1 grows readily on two compounds, 4-hydroxyphenylacetate and 4-aminobutyrate, whose catabolism produces succinic semialdehyde. A single succinic semialdehyde dehydrogenase was detected, native molecular weight 52000, that has NAD as the preferred cofactor and is induced by succinic semialdehyde functions in the oxidation of succinic semialdehyde during growth on both 4-hydroxyphenyl-acetate and 4-aminobutyrate. This contrasts with the situation for Escherichia coli and Pseudomonas putida where two distinct forms of succinic semialdehyde dehydrogenase have been observed.     

Rapid Increase of Pneumococcal Resistance to β-Lactam and Other Antibiotics in Isolates from the Respiratory Tract (Nagasaki,Japan: 1975–1994)

The susceptibility of 101 pneumococcal isolates from the respiratory tract during 1991–1994 was examined and compared with the susceptibility of isolates over the period of 1975–1990. A rapid increase of resistance was seen not only to penicillin but also other antimicrobial agents. During 1991–1994, 38% of all the isolates were resistant to penicillin. The rates of resistance during this period were 16–23% for three newer cephalosporins, 18% for imipenem, 69% for tetracycline, 31% for erythromycin, 20% for chloramphenicol and 9% for clindamycin. The use of antibiotics within one month prior to pneumococcal isolation was correlated with penicillin resistance (P < 0.05). Serotyping of the isolates by antiserum revealed differences in predominant types between penicillin-resistant (19F, 23F, 4) and -susceptible isolates (15, 4, 11A). Our data suggests that anti-pneumococcal antibiotics should be carefully chosen on the basis of susceptibility tests.     

Characterization of a Chlamydia pneumoniae Strain Isolated from a 57-Year-Old Man

The isolation of Chlamydia pneumoniae, especially from elderly persons, is generally not easy. Recently, we succeeded in isolating a chlamydial strain, which was designated KKpn-15, from a 57-year-old man suffering from acute bronchitis. It was compared with well established strains of C. pneumoniae, C. trachomatis and C. psittaci, and its biological properties, such as the morphology of elementary bodies (EBs) and inclusions, and the immunochemistry of EB proteins, were investigated. Based on the results obtained in the present study, it was confirmed that the new chlamydial strain, KKpn-15, is a member of the C. pneumoniae strain and that the organisms of KKpn-15 are useful as an antigen for the serodiagnosis and epidemiology of C. pneumoniae infection.     

Deletion analysis of the essentiality of penicillin-binding proteins 1A, 2B and 2X of Streptococcus pneumoniae

Abstract An internal fragment from each of the penicillinebinding protein (PBP) 1A, 2B and 2X genes of Streptococcus pneumoniae , which included the region encoding the active-site serine residue, was replaced by a fragment encoding spectinomycin resistance. The resulting constructs were tested for their ability to transform S. pneumoniae strain R6 to spectinomycin resistance. Spectinomycin-resistant transformants could not be obtained using either the inactivated PBP 2X or 2B genes, suggesting that deletion of either of these genes was a lethal event, but they were readily obtained using the inactivated PBP 1A gene. Analysis using the polymerase chain reaction confirmed that the latter transformants had replaced their chromosomal copy of the PBP 1A gene with the inactivated copy of the gene. Deletion of the PBP 1A gene was therefore tolerated under laboratory conditions and appeared to have little effect on growth or susceptibility to benzylpenicillin.     

血清SAA、YKL-40及SP-A的联合检测对小儿难治性肺炎支原体肺炎的预测价值分析

摘要 目的：探究血清淀粉样蛋白A（SAA）、几丁质酶样蛋白YKL-40和肺表面活性物质相关蛋白-A（SP-A）表达水平对的联合检测对小儿难治性肺炎支原体肺炎（RMPP）的预测价值。方法：纳入2019年11月至2021年12月期间我院收治的60例MPP患儿作为研究对象,依据病情最终转归将其分为RMPP组和普通肺炎支原体肺炎（GMPP）组,另纳入同期于我院行体格检查的60例健康儿童作为对照组。收集所有受试儿童的临床资料、实验室指标及影像学结果,采用酶联免疫吸附法（ELISA）检测血清SAA、YKL-40和SP-A的表达水平,应用受试者工作特征曲线（ROC）判定各指标单项检测和联合检测的预测效能。结果：MPP组患儿和对照组儿童一般资料相比无统计学差异（P＞0.05）。依据病情最终转归,60例MPP患儿中共有23例（38.33 %）进展为RMPP,RMPP组与GMPP组患儿在白介素-6（IL-6）、C-反应蛋白（CRP）、降钙素原（PCT）、D-二聚体（D-D）等实验室指标以及肺不张、胸腔积液等影像学特征方面相比有统计学差异（P＜0.05）。RMPP组和GMPP组血清SAA、YKL-40和SP-A的表达水平显著高于对照组（P＜0.05）,同时RMPP组血清SAA、YKL-40和SP-A的表达水平显著高于GMPP组（P＜0.05）。血清SAA的最佳截断值为39.75 mg/L,预测RMPP发生的ROC曲线下面积为0.894（95%CI：0.861-0.925）,敏感度为78.26 %,特异度为86.67 %;血清YKL-40的最佳截断值为31.85 ng/mL,预测RMPP发生的ROC曲线下面积为0.754（95%CI：0.634-0.873）,敏感度为73.91 %,特异度为67.21 %;血清SP-A的最佳截断值为35.59 ng/mL,预测RMPP发生的ROC曲线下面积为0.761（95%CI：0.640-0.891）,敏感度为73.91 %,特异度为75.00 %;SAA+YKL-40-1+SP-A三者联合检测预测RMPP的AUC为0.914（95%CI：0.871-0.957）,敏感度为91.30 %,特异度为91.66 %。结论：血清SAA、YKL-40和SP-A表达水平的检测可作为预测RMPP发生的重要生物学指标,且三者联合检测的预测效能较高,可为临床尽早诊断RMPP、尽早干预、改善患儿预后提供一定的帮助。     

Genetics of high level penicillin resistance in clinical isolates of Streptococcus pneumoniae

Abstract Mosaic penicillin-binding proteins (PBP) 1A, 2X and 2B genes were cloned from four clinical isolates of Streptococcus pneumoniae with levels of susceptibility to penicillin ranging from 1.5 to 16 μg benzylpenicillin ml⁻¹. In each instance it was possible to transform either the penicillin-sensitive laboratory strain R6 or a sensitive clinical isolate 110K/70 to the full level of penicillin resistance with these three penicillin-binding proteins alone. Until now it has not been possible to clearly determine whether alterations to PBP1A, 2X and 2B alone were sufficient to attain high level penicillin resistance.     

A study of pathogenic factors of Streptococcus pneumoniae strains causing meningitis

Abstract Pneumococcal meningitis in St. Petersburg in the period 1985–1991 occurred in 1.7–2.3 children per 100 000 annually. The most common serotypes among pneumococcal strains isolated from patients with meningitis were 19, 1, 6, 15, and 2, whereas, among the capsulated strains isolated from carriers, type 3 predominated. Only one third of strains from cases of meningitis were highly virulent for mice (types 1, 2, 3). Hyaluronidase was produced by all the 39 studied strains, 22 (84.6±7.1%) out of 26 strains from patients with otitis media, and only by 15 (11.5±2.8%) out of 130 strains isolated from carriers. Non-capsulated strains lacked this enzyme. Results of intranasal inoculation of pneumococcal strains with different hyaluronidase activity and addition of exogenous hyaluronidase to strains which did not produce the enzyme confirm the hypothesis that this enzyme plays an important role in bacterial dissemination and breaching of the blood brain barrier by pneumococci. It was concluded that high hyaluronidase activity, presence of capsule, and pneumolysin or serotype (1, 2, and 19) despite hyaluronidase titer, are the most important factors contributing to the development of pneumococcal meningitis. The role of the mouse toxic factor is unclear.     

Streptococcus pneumoniae type 3 encodes a protein highly similar to the human glutamate decarboxylase (GAD65)

Abstract A 2.5-kb Sca I fragment of the type 3 pneumococcal strain 406 DNA containing a 1425-nucleotide open reading frame ( gadA ) and encoding a 475-amino acid protein ( M _rmr 54427) was characterised. The gene gadA was expressed in Salmonella typhimurium . Pulsed-field gel electrophoresis and Southern blotting analysis of DNAs prepared from several pneumococcal serotypes showed that only those clinical isolates belonging to serotype 3 harbour the gadA gene. Sequence comparison of GadA with proteins included in the data banks revealed the highest similarity with human glutamate decarboxylase (GAD₆₅) (59% similarity, 28% identity). Auto-antibodies to GAD₆₅ have been associated with the onset of insulin-dependent diabetes mellitus. Interestingly, several epitopes of GAD₆₅ that have been identified as immunodominant are particularly well conserved in the pneumococcal GadA.     

Autolysins are direct involved in the bactericidal effect caused by penicillin in wild type and in tolerant pneumococci

The two pneumococcal autolytic enzymes (an N-acetylmuramoyl-L-alanine amidase and an endo-beta-1,4-N-acetylglucosaminidase) are directly involved in the penicillin-induced killing of Streptococcus pneumoniae. The activity of these lytic enzymes was efficiently controlled in tolerant mutants under physiological conditions.