Esiobu, Nwadiuto

This study evaluated the stability of oral bacteria in healthy subjects and documented
community shifts in smokers and oral/periodontal disease by employing PCR-RFLP,
DGGE and sequence analysis of the 16S rDNA gene from metagenomes and plate-wash
(cultured) bacteria of oral wash from 15 participants,. A stable core of bacterial DNA
fingerprint was detected within and between subjects and did not change over time when
analyzed in smokers and healthy non-smokers. Signature bands in smokers, non-smokers
and periodontal disease subjects were evident suggesting the presence of potential
indicators of health and poor oral health. Taxon diversity was higher in smokers
including members of the genera Rothia, Synechococcus, Neisseria, Thiomargarita and
Pyrobaculum but highest in periodontal disease. The two techniques successfully aligned
the subjects within appropriate categories (based on their oral microbial genetic
patterns)confirming their diagnostic suitability.

Antibiotic resistant bacteria infiltrate drinking water, increase human exposure, and spread into clinical settings. Regulatory agencies need simple test for ARI to monitor environmental quality. This study is first to measure resistance in a consortium of bacteria, not pure cultures. Our rapid method – “In-the-zone” (ITZ) employs a) the size of zones of inhibition b) identity of bacteria in the zone c) number of resistant clones within zones of inhibition and d) type of antibiotic to compute ARI. Results can be obtained within 24 - 48 hrs with very little effort. This semester, we repeated the test and validated the weighting of various parameters. The ITZ assay yield consistent and reproducible data on zones of inhibition of bacteria community. The diameter of inhibition zones was the most important parameter distinguishing resistomes of varying ARI. Landfill, manured garden, and waste plant samples scored highest in antibiotic resistance index compared to beach sand.

Effective decontamination of infectious agents on critical and other hospital surfaces will drastically reduce nosocomial infections and impacts of any biological attack. This research determined the distribution of multiple species of bacteria on 16 different surfaces in two hospitals over a period of time to identify potential reservoirs of infection. The relative efficacy of current hospital disinfectants on endospores were also evaluated to inform policy. Using simulations of endospore-laden surfaces under laboratory conditions, the effects of exposure time, disinfectant concentration and possible synergies with endospore germination stimulant were evaluated. Keyboards, phones, door handles and bed rails were identified as risky hospital surfaces. The location and use of the surfaces were significant determinants of bacterial load. None of the disinfectants tested was sporicidal (<50% reduction). The results of this unique study provide healthcare personnel with a practical guide to control the spread of infection during peace and bio-warfare times.

A novel, 'near-real' time technique; peptide nucleic acid chemilumiscent in situ hybridization (PNA CISH), was developed and validated for detecting, enumerating and identifying potential indicators (Staphyloccus aureus and Pseudomonas aeruginosa) of beach quality. To understand the dynamics of bacterial indicators a plethora of physical, chemical and biological parameters were tested under field and lab conditions. Escherichia coli tagged with green fluorescence protein (GFP) was used to assess the impact of wave energy and rainfall on seawater counts. PNA CISH and plate counts correlated strongly (r = 0.94 to r = 0.86). Temperature, salinity, nutrient availability and predation significantly influenced the survival of indicators. Rainfall and wave energy affected the re-suspension of bacteria from sand onto overlying water. Overall PNA CISH provides a reliable rapid method for beach monitoring. The implications of beach topography and sampling time on the numbers of Clostridium perfringens and other potential indicators are discussed. Data suggest a revision of policy for tropical sandy beaches.

A recent surge in the consumption of shrimps has compelled the aquaculture industry to expand greatly. Bacteriosis poses a major challenge to shrimp cultivation. Probiotic control of disease in larvicultures has been on the rise for the past decade; however, there has been little research to provide required frameworks for this promising technology. In this study, the normal gut flora of the commercially important shrimp, Penaeus vannamei, and its relative, P. duorarum was extensively analyzed to provide a basis for selection of putative probiotic strains. Heterotorphic members of the gut and ambient water were isolated and characterized by culture techniques, microscopy, Biolog biochemical fingerprinting, whole cell crude protein fingerprinting, and 16S rDNA sequence analysis. Non-pathogenic Vibrio harveyi-like strains were prevalent in the gut of both penaied shrimps, regardless of age and source. Community level physiological profiling by principal component analysis showed the gut community was fairly stable throughout shrimp life stages.