NAME: Peptococcus niger
SYNONYM OR CROSS REFERENCE: N/A
CHARACTERISTICS: Peptococcus niger is a gram-positive, non-motile, obligatory anaerobic cocci that is a constituent of the normal human intestinal mucous membranes and umbilicus flora Footnote 1-5. The bacterial cells are 0.3 – 1.3 μm in diameter, and can exist singly, in pairs, tetrads, or in irregular clusters Footnote 6. It can be cultured on enriched blood agar, where it forms smooth, black, irregular colonies (turns grey when exposed to air) that are 1 mm in diameter after 5 days of incubation Footnote 4Footnote 6Footnote 7. The bacterium produces H2S, NH3, and H2, but cannot liquefy gelatine, serum, digest milk, nor ferment carbohydrates Footnote 6. Based on the similarities and relatedness of the G+C content of the Peptococcus and Peptostreptococcus DNA, all species previously classified under the Peptococcus genus has been transferred to the Peptostreptococcus genus, with the exception of Peptococcus niger Footnote 2Footnote 7.
PATHOGENICITY/TOXICITY: The bacteria have been associated with ovine foot rot, and rarely retrieved from animal infections Footnote 8. The very slow growth rate exhibited by P. niger and its lack of distinctive biochemical features may be responsible for its low pathogenicity Footnote 4, as it is seldom isolated from clinical specimens and not commonly cultured from human pathological specimens Footnote 1Footnote 2. A study reported that cultured strains from a rectal abscess, a pilonidal cyst, and a vaginal area swab found only one strain of P. niger amongst 278 other gram-positive cocci examined Footnote 4.
EPIDEMIOLOGY: Worldwide – P. niger is part of the normal human umbilical and intestinal flora Footnote 4.
HOST RANGE: Although uncommon, P. niger has been isolated from the normal flora of the human umbilicus Footnote 4, and in rare cases have been isolated from ovine foot rot disease of hooved animals Footnote 8.
INFECTIOUS DOSE: It is unknown for humans and other animals. However, the infectious dose is likely to be extremely high as P. niger is rarely isolated from human pathogenic specimens Footnote 4.
MODE OF TRANSMISSION: No disease has been specifically linked to P. niger, and thus the route of transmission of the bacteria is not currently known.
INCUBATION PERIOD: Unknown
COMMUNICABILITY: Not known to be communicable between humans.
DRUG SUSCEPTIBILITY: Studies have shown that strains are susceptible to penicillin, ampicillin, azlocillin, piperacillin, mexlocillin, metronidazole, cefuroxime, cefoperazone, cefotaxime, imipenem, erythromycin, clindamycin, chloramphenicol, and tetracycline Footnote 4Footnote 9.
DRUG RESISTANCE: Resistance to metronidazole and lincomycin have been reported Footnote 4.
SUSCEPTIBILITY TO DISINFECTANTS: Most bacteria are susceptible to 1% sodium hypochlorite, 2% glutaraldehyde, formaldehyde, and 70% ethyl or isopropyl alcohol 10.
PHYSICAL INACTIVATION: Inactivated by moist heat (121°C for 15 – 30mins) and dry heat (160 - 170°C for 1-2 hours) Footnote 11.
SURVIVAL OUTSIDE HOST: Unknown, but because of its slow rate of growth on enriched blood agar Footnote 1Footnote 4, it is unlikely that the bacteria can survive under harsh conditions outside the host or in laboratory effluent.
SURVEILLANCE: Monitor for symptoms.
FIRST AID/TREATMENT: Administer proper drug treatment.
IMMUNIZATION: None available.
PROPHYLAXIS: None available.
LABORATORY-ACQUIRED INFECTIONS: None reported to date.
SOURCES/SPECIMENS: Human intestinal or umbilical tissue, and mucous membranes. P. niger H4 strain can be isolated from the human gastrointestinal tract, as well as from the hooves of animals afflicted with ovine foot rot Footnote 2Footnote 3Footnote 8Footnote 12.
PRIMARY HAZARDS: Handling of infected human intestinal or umbilical tissue, coming into contact with mucous membranes or infected animals hooves that carry the bacteria may be a hazard Footnote 2Footnote 3Footnote 8.
SPECIAL HAZARDS: None
RISK GROUP CLASSIFICATION: Risk Group 1
CONTAINMENT REQUIREMENTS: Containment Level 1 facilities, equipment, and operational practices for work involving infectious or potentially infectious material Footnote 13.
PROTECTIVE CLOTHING: Properly fastened protective laboratory clothing. Gloves when direct skin contact with infected materials or animals is unavoidable Footnote 14.
OTHER PRECAUTIONS: None
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incineration Footnote 13.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelled.
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: November 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada
Although the information, opinions and recommendations contained in this Pathogen Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Copyright © Public Health Agency of Canada, 2011 Canada