Novel Genes Required for Surface-Associated Motility in Acinetobacter baumannii

Acinetobacter baumannii is an opportunistic and increasingly multi-drug resistant human pathogen rated as a critical priority one pathogen for the development of new antibiotics by the WHO in 2017. Despite the lack of flagella, A. baumannii can move along wet surfaces in two different ways: via twitching motility and surface-associated motility. While twitching motility is known to depend on type IV pili, the mechanism of surface-associated motility is poorly understood. In this study, we established a library of 30 A. baumannii ATCC® 17978™ mutants that displayed deficiency in surface-associated motility. By making use of natural competence, we also introduced these mutations into strain 29D2 to differentiate strain-specific versus species-specific effects of mutations. Mutated genes were associated with purine/pyrimidine/folate biosynthesis (e.g. purH, purF, purM, purE), alarmone/stress metabolism (e.g. Ap4A hydrolase), RNA modification/regulation (e.g. methionyl-tRNA synthetase), outer membrane proteins (e.g. ompA), and genes involved in natural competence (comEC). All tested mutants originally identified as motility-deficient in strain ATCC® 17978™ also displayed a motility-deficient phenotype in 29D2. By contrast, further comparative characterization of the mutant sets of both strains regarding pellicle biofilm formation, antibiotic resistance, and virulence in the Galleria mellonella infection model revealed numerous strain-specific mutant phenotypes. Our studies highlight the need for comparative analyses to characterize gene functions in A. baumannii and for further studies on the mechanisms underlying surface-associated motility.

Induction of Cyclooxygenase 2 by Streptococcus pyogenes Is Mediated by Cytolysins

Prostaglandin E2 (PGE2), an arachidonic acid metabolite regulating a broad range of physiological activities, is an important modulator of the severity of infection caused by Streptococcus pyogenes. Here, we investigated the role of streptococcal cytolysin S (SLS) and streptococcal cytolysin O (SLO) in the induction of cyclooxygenase-2 (COX-2), the rate-limiting enzyme in the synthesis of prostaglandins, in in vitro cultured macrophages and during in vivo infection. Macrophages were infected with S. pyogenes wild type or with the isogenic mutant strains deficient in SLS (ΔSLS), SLO (ΔSLO), or both (ΔSLS/ΔSLO), and the expression of COX-2 was determined at the transcriptional and the protein level. The results indicated that S. pyogenes induced expression of COX-2 and concomitant synthesis of PGE2 in macrophages mediated by the synergistic activity of both SLS and SLO, and involved calcium and the PKC/JNK signaling pathway. These results were validated using recombinant cytolysins. In a murine skin infection model, COX-2-positive cells were found more abundant at the site of S. pyogenes wild-type infection than at the site of infection with ΔSLS/ΔSLO mutant strain. These findings suggest that inhibitory targeting of SLS and SLO could ameliorate the adverse effects of high levels of prostaglandins during S. pyogenes infection.

Acute and chronic toxicity toward the bacteria Vibrio fischeri of organic narcotics and epoxides: structural alerts for epoxide excess toxicity

The acute and chronic bacterial toxicity of 34 organic compounds comprising 19 baseline narcotics and 15 epoxides has been determined with regard to 30-min bioluminescence and 24-h growth inhibition in terms of EC50 (effective concentration 50%) values employing Vibrio fischeri. For the narcotics, linear regression of log EC50 on log Kow (octanol/water partition coefficient) yields r2 (squared correlation coefficient) and rms (root-mean-square error) values of 0.95 and 0.44 (30-min), and 0.94 and 0.34 (24-h), respectively. Employing the resultant baseline narcosis models, toxicity enhancement (Te) values were derived as a ratio of narcosis-predicted over experimental EC50 for the epoxides. For seven aliphatic epoxides, log Te was below 1 in both assays, indicating narcosis-range toxicity with regard to 30-min bioluminescence and 24-h growth inhibition. Concerning eight nonaliphatic epoxides, log Te values up to 2.4 were observed, reflecting excess toxicity through an enhanced electrophilic reactivity of the compounds. Here, however, the intercorrelation between both assays was very low (r2 = 0.09). The results are discussed in terms of electronic substituent effects activating an SN2-type epoxide reaction with nucleophilic protein sites and side-chain activation offering alternative electrophile-nucleophile reaction routes at side-chain sites, leading to respective structural alerts as indicators of excess toxicity. Surprisingly, 30-min bioluminescence appears to be slightly more sensitive to chemical stress than 24-h growth, which holds both for baseline narcotics and for most of the epoxides. This is also reflected by effective narcosis doses 50%, ED50, of 7.1 mmol/kg (30-min) and 7.7 mmol/kg (24-h) estimated from narcosis theory. Keeping in mind the different end points (bioluminescence vs growth) involved, this finding demonstrates that chronic toxicity is not always more sensitive than acute toxicity, calling for analyses with regard to further respective cases and associated mechanistic causes.

Foreign body in upper airway. Unsuspected cause of obstruction

Airway obstruction from a foreign body is usually an acute life-threatening event. In this case, a complete upper dental plate was the unsuspected cause of intermittent respiratory distress. The authors discuss the clinical and laboratory findings and suggest ways to prevent unnecessary delays in diagnosis and treatment.

[Status of computerized tomography for the diagnosis of diseases of the gallbladder and bile ducts]

After a short introduction to the computed tomographic examination technique and the demonstrability of the anatomic structures in the section picture the findings in cholelithiasis, cholecystitis and cholangitis, in the malignoma of the biliary system as well as of the traumatic lesion of the bile ducts are described. In the diseases mentioned the reliability of the computed tomography is high and it does not fall behind the sonography. Nevertheless, the sonography is primarily to be used on account of missing radiation exposure, smaller costs and broader spread of appliances. Then the computed tomography is performed in selected cases which remain unclear such as in complicated lithiases and in the suspicion of malignoma.

Botulinum ADP-ribosyltransferase C3. Purification of the enzyme and characterization of the ADP-ribosylation reaction in platelet membranes

A novel ADP-ribosyltransferase C3 was purified to homogeneity from filtrates of certain strains of Clostridium botulinum type C by ammonium sulfate precipitation, gel filtration, ion-exchange chromatography and heat treatment. The molecular mass of botulinum ADP-ribosyltransferase C3 was found to be 25 kDa. In the presence of [32P]NAD but not with [carbonyl-14C]NAD, C3 labelled 21-24-kDa protein(s) in membranes of human platelets and other tissues. The Km value of the ADP-ribosylation reaction for NAD was about 2 microM. Labelling of the 21-24-kDa protein(s) by C3 was largely reduced by addition of nicotinamide. Snake venom phosphodiesterase cleaved the ADP-ribose attached to the 21-24-kDa protein(s) by C3 and released 5'AMP. C3 catalyzed hydrolysis of [carbonyl-14C]NAD and released [carbonyl-14C]nicotinamide. ADP-ribosylation of 21-24-kDa platelet membrane protein(s) was biphasically regulated by Mg2+, Mn2+ and Ca2+. In the absence of free divalent cations GTP, GTP[gamma S] and GDP but not GDP[beta S], GMP, ATP or ATP[gamma S] increased labelling by C3. In the presence of Mg2+, GTP[gamma S] was inhibitory. Guanine nucleotides prevented heat inactivation of the substrate protein(s) with the rank order GTP[gamma S] = GTP = GDP greater than GDP[beta S] greater than GMP much greater than ATP = GMP = ATP[gamma S]. The data support the view that the novel ADP-ribosyltransferase C3 modifies eukaryotic 21-24-kDa GTP-binding protein(s).

[Complaints following cholecystectomy]

A subdivision of the most frequent complaints after cholecystectomy is given. For the clarification of the manifold causes of these inhomogeneous pictures of complaints a considerable diagnostic expenditure is necessary, in which case the importance of ERCP is particularly emphasized. In concrements of the choledochus as well as in short-distance papillary stenoses nowadays above all the endoscopic papillotomy is therapeutically taken into consideration. Recommendations are given for the medicamentous treatment of functional complaints.

[Relation of radiographic and clinical findings to the pathomorphological changes in Wegener's granulomatosis]

On the basis of two own observations the clinical and radiological routine methods undergo a critical judgment concerning their valency for the diagnosis of Wegener's granulomatosis. The two patients showed the picture of a severe septical disease with high fever and expressed inflammatory changes of the biological reactions. In the first observation a pulmonary round focus and terminally the renal failure, in the second case severe inflammatory changes of the lungs without response to antibiotic therapy were in the foreground. The appearance of this disease as generalized vasculitis is conditioned by the manifold clinical symptomatology and thus renders the diagnostics extraordinarily difficult. The simultaneous affection of the nasopharyngeal space, of the lung and the kidneys may be a guide for the diagnosis. The X-ray findings of the lung are not able to found sufficiently the diagnosis.

[Intramural diverticulosis and adenomyomatosis of the gallbladder]

Issuing from an own observation the clinical picture of the adenomyomatosis and the intramural diverticulosis of the gall bladder is considered from the clinical, radiological and pathologo-anatomical point of view. The opinions which are not homogeneous are explained and discussed. Also abortive forms may radiologically be proved with probability.

[Pulmonary metastasizing of prostatic carcinoma--source of errors in the ambulatory x-ray examination of lungs]

It is reported on eight patients with a primary carcinoma of the prostatic gland who were admitted to the hospital for clinical clarification of conspicuous pulmonary findings. The radiological findings of a general radiograph of the thorax are multiform and for themselves alone they do not permit an etiological coordination. For this reason the demand can be derived in patients of the adequate age group with tumour symptomatology can also be thought of a carcinoma of the prostatic gland and already during the examination in the outpatient department to carry out a palpatory examination and, if possible, to make a general radiograph of spinal column and pelvis, since in these cases the diagnosis can be made already before admission.