An Interesting Case Series of Actinomyces odontolyticus and Lactobacillusplantarum Infection in A Tertiary Care Hospital in New Delhi

Case Presentation

Case 1

A 50-year-old female presented with discharging sinuses on the left foot one month prior to the surgery outpatient department (OPD). Local examination revealed painless swelling with edema on the left foot with multiple sinuses and discharge with white granules. X-ray of the foot showed multiple osteolytic lesions.

The female patient was a farmer and has been noted to be noncompliant with her Diabetes Mellitus treatment.

Case 2

A 60-year-old male presented with sloughing and discharge from a chest and upper abdomen lesion to the emergency casualty. On local examination, there was a painful swelling with discharge from the lesions. The patient is a known case of pemphigus vulgaris, a history of alcohol intake, and a family history of diabetes mellitus.

Case 3

A 16-year-old male, who sustained thermal burns covering 20% of his total body surface area one and a half months ago, presented to the Burns and Plastic OPD with sloughing and putrid discharge from the burn wounds. On examination, he was conscious, oriented, and hemodynamically stable. Local examination revealed a post-burn raw area over the left thigh, lower third of the left leg, medial aspect of the right thigh, and lower abdomen. Additionally, Grade IV burns were noted on the left sole and sacrum. Pus discharge and tissue sloughing were present over the affected areas. Two samples were collected at a 7-days interval for anaerobic culture and sensitivity testing. The patient had received multiple courses of antibiotics for an extended period, with a delayed initiation of antimicrobial therapy covering anaerobes. He also administered a probiotic combination of Lactobacillus rhamnosus GG and L. plantarum. Additionally, multiple carious teeth were noted.

Treatment

All patients participating in the study signed an informed consent. Samples were received in anaerobic conditions in Robertsons’s cooked meat media (RCM). RCM was incubated for 24 hours and was inoculated in a triplicate manner on neomycin anaerobic sheep blood agar (NSBA) for anaerobic incubation and sheep blood agar (SBA) for aerobic incubation agar. One NSBA (sealed with parafilm) plate was incubated anaerobically in a Gas Pack Jar for 72 hours at 37˚C, one SBA plate under a CO₂ incubator for 48 hours at 37˚C in an atmosphere containing 5-10% CO₂, and one aerobically SBA at 37˚C for 48 hours. NSBA plates were examined for growth after 72 hours, and Gram's stain was performed. No growth was detected in aerobic and CO₂-incubated plates. Pure isolated colonies from a Gas pack jar were subjected to manual biochemical tests like Gram’s stain, motility, 15% catalase test, Spot Indole test, modified Ziehl Neelsen test, three-disc potency test, aerotolerant test, nitrate reduction test followed by automation technique confirmation by VITEK-2. The sensitivity testing was done by using the pour plate method using Epsilometer strips (E-strips).^10,11 From case 1 and case 3 (first sample), A. odontolyticus was isolated after 7 days of anaerobic incubation while from case 2 and case 3 (second sample), L. plantarum was isolated. The sensitivity profile of all 4 organisms is depicted in Table 1. Case 1 was treated with surgical excision followed by oral ampicillin for 10 days. Case 2 left against medical advice 10 days after admission. Case 3 died due to septicemia and septic shock after 7 days of admission. Figures 1, 2 and 3 depict the colony on NBA and A. odontolyticus and L. plantarum, and Grams's stains of A. odontolyticus, respectively.

Discussion

Actinomyces species are Gram-positive filamentous non-acid fast anaerobic bacteria that typically colonize the human oral cavity, urogenital tract, and gastrointestinal tract. A. odontolyticus infection is a bacterial infection ranging from a chronic deep-seated abscess and intracranial infections to bacteremia and is almost exclusively associated with immunosuppression, which is also reflected in this study.^2-5

L. plantarum is Gram’s positive long anaerobic non-spore-forming bacilli. It is a regular human respiratory, gut, and genitourinary tract commensal that has beneficial immunomodulatory properties and, hence, is widely used as a probiotic agent. Recently, L. plantarum has been applied for the treatment of various chronic and cardiovascular diseases such as Alzheimer’s, Parkinson’s, and diabetes mellitus. These agents, however, can cause bacteremia and septicemia in critically ill patients. Hence, blood culture and molecular typing are necessary. Several studies have recognised L. plantarum as a causative agent of infection, as also depicted in this study.^6-9

An increase in the metronidazole drug's minimum inhibitory concentration (MIC) value has been encountered in anaerobes. It is a major concern as it is the drug of choice for most anaerobes. Sensitivity testing for anaerobes is not performed routinely, which results in under-reported metronidazole drug resistance. Metronidazole resistance detection is higher with improvements in molecular detection and antimicrobial stewardship programs. Sensitivity to metronidazole drug in Actinomyces spp. ranges from 17% in A. odontolyticus (6% in all Actinomyces spp.), <5% as shown by Wolf LJ to almost uniformly resistant as depicted in Case 1 and Case 3 of this study.¹² There are no established treatment guidelines for Lactobacillus species infections because of a lack of adequate antimicrobial suscep-tibility data. In multiple studies, good susceptibility was noted to erythromycin, clindamycin, and gentamicin, as also depicted in Case 2 of this study. Few studies have shown high resistance to cefoxitin, metronidazole, glycopeptides, and aminoglycosides similar to Case 3 (second sample) of this study.^12-15

In conclusion, the injudicious use of metronidazole drug should be avoided. Patients with such clinical conditions should kept under vigilance for anaerobic infections which requires regular training of clinical and paramedical staff, and antimicrobial stewardship should be strictly implemented for anaerobic organisms to avoid resistance and increased MIC to drugs. Few studies having probiotics have been reported to cause bacteremia, hence molecular typing of the strain is necessary.

Funding

Nil

Conflict of Interest

Nil