Catalase Test as an Aid to the Identification of Enterobacteriaceae

Although the catalase test has been used for many years for rapid differentiation of the genera of gram-positive organisms, little has been said about its use in the family Enterobacteriaceae. It was further noted that a wide variety of methods exist for the execution of the catalase test, that there is no universally accepted strength specified for the hydrogen peroxide, and that no gradations for the vigor and speed of the reaction have been mentioned. Under the conditions of the clinical laboratory, we have developed a simple, rapid, and accurate method for the catalase test that has been of great value as an aid in the identification of the Enterobacteriaceae. With 3% H(2)O(2), it was observed that Serratia, Proteus, and Providencia were vigorous catalase reactors. Only Salmonella and rare Escherichia, Enterobacter, and Klebsiella isolates were moderate catalase reactors. Escherichia and Shigella strains were mostly nonreactive, with less than one-third weekly (+) reactive, whereas most Enterobacter strains tended to be weakly reactive. Klebsiella strains were divided equally between nonreactive and weakly reactive. In practice, this test was also of great value in discerning nonpigmented Serratia cultured from the hospital environment and in detecting mixed flora containing nonspreading Proteus.     

Isolation of Salmonellae from Foods Samples: V. Determination of the Method of Choice for Enumeration of Salmonella

Comparison of three methods by which salmonellae may be isolated and enumerated from dried albumen, direct inoculation of enrichment media, centrifugation of samples, and pre-enrichment in noninhibitory media, reveals pre-enrichment to be the method of choice.

The superiority of pre-enrichment manifests itself in replicate aliquots of the same sample by producing a statistically significant increase in numbers of isolations of salmonellae and in empirical use with various albumen samples by consistently higher values of most probable numbers (MPN).

The primary factor involved in this superiority appears to be the greater ability of small numbers of salmonellae to initiate growth in the nonselective mannitol purple sugar broth than in the inhibitory enrichment media.

The method of analysis recommended entails inoculation of mannitol broth pre-enrichment medium, transfer of 24-hr culture aliquots to tetrathionate broth, and streaking on brilliant green agar for isolation of salmonellae.

     

Pulmonary responses to phospholipase A2 in the perfused guinea pig lung

We examined the effect of phospholipase A2 (PLA2; Naja naja) challenge on pulmonary hemodynamics, airway constriction, and fluid filtration in isolated Ringer-perfused guinea pig lungs. Intratracheal PLA2 (10-100 U) produced dose-dependent increases in pulmonary arterial pressure, intratracheal pressure, and lung weight, although intravenous PLA2 administration had no effect on monitored variables. Morphological features indicative of airway constriction and pulmonary edema were observed by light microscopy. PLA2-induced increases in intratracheal pressure and/or lung weight were attenuated to varying degrees by pretreatment with indomethacin (1 microM, a cyclooxygenase inhibitor), ICI-198,615 (1 microM, a leukotriene D4 receptor antagonist), and WEB 2086 (1 microM, a platelet-activating factor antagonist). PLA2-induced increases in pulmonary arterial pressure and intratracheal pressure were also reduced in lungs removed from animals pretreated with dexamethasone (50 mg/kg ip for 2 days; a steroidal antiinflammatory agent). Pyrilamine (1 microM, a histamine1-receptor antagonist) and Takeda AA861 (1 microM, a delta 5-lipoxygenase inhibitor) did not produce significant inhibitory effects on PLA2-induced pathophysiological changes. Intratracheal instillation of high-dose platelet-activating factor (50 micrograms) or lysophosphatidylcholine (100 micrograms) produced gradual increases in intratracheal pressure and lung weight, but these changes were not as large as those induced by PLA2. Thus these studies suggest that resident cell populations associated with airways may play an important role in PLA2-induced pathophysiological changes in the perfused guinea pig lung. These PLA2-induced effects are most likely partially mediated by generation of eicosanoids and platelet-activating factor.     

First report of metazoan parasites from the cichlid Pseudocrenilabrus philander and the cyprinid Enteromius paludinosus in a South African Ramsar wetland

Parasites of two small fish species from a Ramsar wetland in South Africa were studied in 2014–2015. The cichlid Pseudocrenilabrus philander (Weber, 1897) was parasitised by the copepod Lernaea cyprinacea Linnaeus, 1758, the monogenean Gyrodactylus thlapi Christison, Shinn & van As, 2005 and four gryporhynchid metacestode (Cyclophyllidea) species: Paradilepis scolecina (Rudolph, 1819), Paradilepis maleki Khalil, 1961, Neogryporhynchus lasiopeius Baer & Bona, 1960 and Valipora campylancristrota (Wedl, 1855). The cyprinid Enteromius paludinosus (syn. Barbus paludinosus) (Peters, 1852) was infected with the monogenean parasites Dogielius intorquens Crafford, Luus-Powell & Avenant-Oldewage, 2012, Dactylogyrus teresae Mashego, 1983, and three Dactylogyrus spp. These results represent several new locality as well as host records and further contribute information on the parasitic diversity in the Barberspan Ramsar wetland.     

A spectacular new Philippine monitor lizard reveals a hidden biogeographic boundary and a novel flagship species for conservation

As humans continue to explore the last uncharted regions of the planet, discoveries of previously unknown species of large vertebrates have become infrequent. Here, we report on the discovery of a spectacular new species of giant, secretive, frugivorous, forest monitor lizard (Genus: Varanus) from the forests of the northern Philippines. Using data from morphology and mitochondrial and nuclear DNA sequences, we demonstrate the taxonomic distinctiveness of this new 2 m long species and provide insight into its historical biogeography and systematic affinities. Our molecular phylogenetic analyses indicate that the new species is closely related to Varanus olivaceus (from southern Luzon and nearby islands), but it differs from this and other varanids with respect to characteristics of scalation, colour pattern, body size, anatomy of the reproductive organs and genetic divergence. The new species appears to be restricted to forests of the central and northern Sierra Madre mountain range; it is separated from the range of V. olivaceus by a more than 150 km stretch that includes at least three low-elevation river valley barriers to dispersal. This discovery identifies a seldom-perceived biogeographic boundary and emphasizes the need for continued biodiversity research in the megadiverse conservation hotspot of the Philippines. It is anticipated that the new species will serve as an important flagship species for conservation efforts aimed at preserving the remaining forests of northern Luzon.     

The distribution and species characteristics of the Culicoides biting midge fauna of South Africa

Abstract.  1. Monthly light trap collections over 2 years at 39 sites across South Africa captured over 3 000 000 Culicoides of 86 species, some of them known vectors of African horse sickness and bluetongue viruses.
2. To aid disease control and risk evaluation, cluster analysis and association measurements were carried out on species present at each site. Six species occurred at almost all sites. From the remaining 80 species, eight clusters were identified at > 48% similarity.
3.  Culicoides citroneus and C. krameri were characteristic of cluster 8, C. loxodontis of cluster 4, and two numbered, but un-named, species, C. #119 and C. #89 , of cluster 5.
4. Multiple anova and multiple discriminant analysis on the climatic and geographic parameters of sites in each cluster gave two significant discriminant functions that explained 91.5% of the variance between clusters. Function 1 contrasted sites with high cold cloud duration and high vegetation index with sites with high wind speeds. Function 2 contrasted upland clusters that also had high cold cloud duration with hotter, lower altitude sites.
5. Species associations were explained in terms of biotic provinces, based on ecogeographic factors that have previously been useful to describe communities of birds.
6. None of the clusters was ideal for siting an African horse sickness-vector free quarantine station as C. imicola and C. bolitinos , the main vectors, were found in all clusters but in very low abundance in cluster 5. The analysis provides a firm basis for studying the changing patterns of species distribution under varying climatic influences.