Which organism is identified by branching rods in an oral infection?

The organism identified by branching rods in an oral infection is Actinomyces. This genus of bacteria is known for its characteristic filamentous, branched morphology which resembles that of fungi under the microscope. Actinomyces can be part of the normal flora of the mouth and throat, but it can also cause opportunistic infections, particularly in cases where there is disruption of mucosal barriers, such as following dental procedures or trauma.

The infections caused by Actinomyces, such as cervicofacial actinomycosis, typically present with abscesses and draining sinus tracts, which may discharge sulfur granules, a key diagnostic feature. This forms a distinct clinical picture that helps differentiate Actinomyces from other organisms.

In contrast, the other choices do not present with branching rods or are not typically associated with oral infections. Bacteroides fragilis, for example, is an anaerobic bacterium commonly found in the gut and associated with intra-abdominal infections but does not have the branching morphology seen in Actinomyces. Streptococcus pneumoniae is a spherical organism that typically appears as diplococci and is primarily associated with pneumonia and meningitis rather than oral infections characterized by branching rods. Clostridium tetani