An epidemic of late-onset sepsis due to type Ib/c group B Streptococcus (Ib/c-GBS) occurred in a neonatal intensive care unit (NICU). During a seven-week period, five very low birth weight infants (index cases [ICs]) more than four weeks of age became bacteremia Bacteriologic surveillance of neonates revealed persistent colonization in three ICs and identified three asymptomatic carriers (ACs). All ICs and one AC acquired Ib/cGBS nosocomially, whereas the other two ACs were colonized at birth. Among nursery personnel, 39*70 carried GBS, but only two harbored Ib/c-GBS. Although phage typing of Ib/c-GBS isolates identified two patterns of susceptibility, we believe a single strain was involved in the epidemic, because the patterns overlapped and most isolates carried the same lysogenic phage. Analysis of events suggested infant-to-infant spread via the hands of personnel, but acquisition from the colonized staff was also possible. The control measures instituted prevented further spread of Ib/c-GBS in the NICU.

Unusual Occurrence of an Epidemic of Type Ib/c Group B Streptococcal Sepsis in a Neonatal Intensive Care Unit

Three pentachlorophenol (PCP) degrading bacterial strains were isolated from sediment core of pulp and paper mill effluent discharge site. The strains were continuously enriched in mineral salts medium supplemented with PCP as sole source of carbon and energy. One of the acclimated strains with relatively high PCP degradation capability was selected and characterized in this study. Based on morphology, biochemical tests, 16S rDNA sequence analysis and phylogenetic characteristics, the strains showed greatest similarity with Acinetobacter spp. The strain was identified as Acinetobacter sp. ISTPCP-3. The physiological characteristics and optimum growth conditions of the bacterial strain were investigated. The results of optimum growth temperature revealed that it was a mesophile. The optimum growth temperature for the strain was 30 degrees C. The preferential initial pH for the strain was ranging at 6.5-7.5, the optimum pH was 7. The bacterium was able to tolerate and degrade PCP up to a concentration of 200 mg/l. Increase in PCP concentration had a negative effect on biodegradation rate and PCP concentration above 250 mg/l was inhibitory to its growth. Acinetobacter sp. ISTPCP-3 was able to utilize PCP through an oxidative route with ortho ring-cleavage with the formation of 2,3,5,6-tetrachlorohydroquinone and 2-chloro-1,4-benzenediol, identified using gas chromatograph-mass spectrometric (GC-MS) analysis. The degradation pathway followed by isolated bacterium is different from previously characterized pathway.

Enrichment, isolation and characterization of pentachlorophenol degrading bacterium Acinetobacter sp. ISTPCP-3 from effluent discharge site

Polycyclic aromatic hydrocarbons (PAHs) are wide spread industrial pollutants that are released into the environment from burning of coal, distillation of wood, operation of gas works, oil refineries, vehicular emission, and combustion process. In this study a lipolytic bacterium was isolated from mixed stover compost of Saccharum munja and Brassica campestris. This strain was identified by both classical and 16S ribosomal DNA sequencing method and designated as Serratia marcesencs L-11. HPLC-based quantitation revealed 39- 100% degradation of PAH compounds within seven days. Further its ability to produce catechol 1, 2-dioxygenase (1.118 μM mL−1 h−1) and biosurfactants (0.88 g L−1) during growth in PAH containing medium may be responsible for its PAH-degradation potential. This novel bacterium with an ability to produce lipases, biosurfactant and ring cleavage enzyme can prove to be useful for in-situ degradation of PAH compounds.

Deciphering the traits associated with PAH degradation by a novel Serratia marcesencs L-11 strain.

The organism Acinetobacter sp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidative ortho dehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O(2) per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H(2)(18)O and (18)O(2) indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by the ortho ring cleavage catechol-1,2-dioxygenase to cis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA(-) derivative and a 2C4NBA(+) transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12.

https://aem.asm.org/content/aem/77/18/6606.full.pdf

Novel Pathway for the Degradation of 2-Chloro-4-Nitrobenzoic Acid by Acinetobacter sp. Strain RKJ12

A two-stage typing scheme in routine use in this laboratory is described. The strains of group B streptococci (GBS) are first serotyped and then, if necessary, phage-typing is performed. Serotyping lacks discrimination because almost 40% of strains handled carry either the Ia/c or III/R antigens. On the other hand, the typability rate with phages is less than 80%. The evidence from the combined scheme is consistent with the view that GBS infections occurring within the first five days of life are, with few exceptions, due to acquisition of the mother's flora. After this time the infecting strain may come from other sources. Human and bovine strains of GBS belong predominantly to two recognizably different populations that can be distinguished by antigenic and biochemical differences. There are no patterns of lysis by phages characteristic of either human or bovine strains.

Typing of Streptococcus agalactiae (Lancefield group B).

Publisher Summary This chapter discusses the development of a phage-typing system for Group B streptococci. The application of Lancefield's serological method to the haemolytic streptococci has led to the recognition of some major pathogenic groups for man, including Groups A, B, C, D, and G. Groups A, B, and C can be equated with species described on the basis of biochemical characteristics: Streptococcus pyogenes (Group A), S. agalactiae (Group B), and S. equisimilis (Group C). Group D streptococci can be subdivided into three main species: S. bovis , S. faecalis, and S. faecium , which all possess the same group antigen. To trace the spread of these organisms or relate strains to particular diseases, further identification of the organisms beyond the species is required. An ideal typing system should reproducibly identify related strains as being the same and unrelated strains as being different. However, factors such as genetic variation and experimental conditions influence the reproducibility of any typing method. Phage typing has been used in the construction of discriminatory systems for some common pathogens—notably, S. aureus —but streptococcal bacteriophages have been studied much less intensively than staphylococcal bacteriophages and Gram-negative bacilli. Phage sensitivity has been used as an additional means of subdividing certain types of Group A streptococci and lysotyping schemes have been proposed for Groups A, C, and D.

J. Stringer

Papers

1 Phage typing of Streptococcus agalactiae