Isolation of obligate anaerobic bacteria from clinical specimens.

This research paper studied the presence of obligate anaerobic bacteria in samples from various animals and evaluated their resistance to different antimicrobial drugs. The findings highlight the predominance of Bacteroides species and suggest a need for multi-effective antimicrobial treatments in anaerobic infections.

Research Context and Methodology

• The researchers examined 467 samples gathered from dogs, cows, horses, and cats over a span of 5 years at the Atlantic Veterinary College’s diagnostic laboratory, and this investigation was aimed at identifying anaerobic bacteria.
• Anaerobic bacteria, which do not require oxygen for growth, are implicated in various infectious conditions in animals. Some infections caused by these bacteria necessitate specific antimicrobial drugs for effective treatment.
• The isolation and identification of bacterial isolates were performed using traditional methods and commercial anaerobe identification systems,thus ensuring accuracy in results.

Findings and Analysis

• Out of 467 specimens, 108 (23.1%) tested positive for one or more types of anaerobic bacteria. This rate was in line with previous similar studies, corroborating the methodology used.
• The researchers found that Gram-negative anaerobes were the most common. Of these, Bacteroides made up 51.5%, meaning they were the most prevalent. The most common single species was Bacteroides fragilis representing about 26% of gram-negative anaerobes.
• Also isolated from positive specimens were 83 gram-positive anaerobes, which included a significant representation of clostridia and gram-positive, non-sporulating anaerobes. The most common among these was the genus Peptostreptococcus, with P. anaerobius being most prominent.

Implications and Recommendations

• Most of the samples with anaerobe-positive findings yielded more than one species of anaerobic bacterium. This correlated with the most common isolation of Bacteroides.
• This observation underscores the polymicrobial nature of anaerobic infections, meaning a single infection is caused by multiple species of bacteria.
• As such, the researchers recommended that antimicrobial agents effective against multiple species of anaerobes should be chosen for successful treatment.
• They also found Metronidazole, clindamycin, and chloramphenicol to be active against multiple anaerobes, rendering them potentially effective treatment options for these infections.