Isolation and identification of enterococcal species

Characterization of enterococcal isolates.

Enterococci grew as small to medium gray colonies on sheep blood agar, with alpha or gamma hemolysis. They hydrolyzed esculin producing black colonies on Bile esculin agar (figure 4.3), produced small pink colonies on Slantez and Bartley agar. All strains grew at 45˚C, in 6.5% NaCl and are catalase negative, and showed Gram-positive cocci in pairs or short chains in gram stained films.

Fecal carriage of enterococci

Ninety four percent of the 100 hospitalized patients and 89% of 100 individuals living in the community carried enterococci in their gastrointestinal tracts.

 Species distribution

All enterococcal isolates were identified to species level using API 20 Strep (Figures 4.4 - 4.8). Among hospitalized patients, E. faecium was the predominant identified species) 37%) followed by E. faecalis (28%), E.  gallinarum (14%), E. durans (9%) and E. avium (6%). While among the non-hospitalized individuals, E. faecalis was the predominant species identified (34%) followed by E. faecium (27%), E. avium (14%), E.  gallinarum (11%) and E. durans (3%). There were no statistically significant differences in the species distribution among hospitalized patients and non-hospitalized individuals (P = 0.073).

VRE colonization

VRE were isolated from 65% of the hospitalized patients and 39% of the individuals living in the community. There is a statistically significant differences among hospitalized and non-hospitalized groups with regard to their carriage of VRE (P = <0.01).

Table: Comparison between VRE isolates based on source

 

Enterococcus source	Vancomycin Susceptibility n %
	Resistant	Sensitive	Intermediate	Total
Hospitalized	65 69.1%	22 23.4%	7 7.4%	94 100.0%
Non-hospitalized	39 43.8%	44 49.5%	6 6.7%	89 100.0%

P= < 0.01