Oral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci in irradiated, dentate, xerostomic individuals

Oral Microbiol Immunol. 2001 Feb;16(1):1-9. doi: 10.1034/j.1399-302x.2001.160101.x.

Abstract

This study aimed at investigating the oral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci in head- and neck-irradiated, dentate, xerostomic individuals. Subjects were recruited from a nasopharyngeal carcinoma clinic and were segregated into group A: <60 years (n=25, 48+/-6 years, 5+/-5 years post-irradiation) and group B: >or=60 years (n=8, 67+/-4 years, 2+/-2 years post-irradiation) and were compared with age- and sex-matched normal individuals, group C: <60 years (n=20, 44+/-12 years) and group D: >or=60 years (n=10, 70+/-3 years). Selective culture of the oral rinse samples was carried out to isolate, quantify and speciate (using API 20E kit) aerobic and facultatively anaerobic gram-negative rods and cocci recovery. All test subjects were put under comprehensive oral and preventive care for 3 months, and 12 group A and 5 group B subjects were recalled for reassessment of aerobic and facultatively anaerobic gram-negative rods and cocci colonization. All identical isolates, pre- and post-hygienic care, were phenotypically (Vitek, Hazelwood, MA and antibiogram profile) and genotypically (pulsed-field gel electrophoresis) evaluated. The aerobic and facultatively anaerobic gram-negative rods and cocci isolated from the first round oral rinse samples included: Acinetobacter, Neisseria, Chryseomonas, Flavimonas, Pseudomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, Flavobacterium and Weeksella species. The aerobic and facultatively anaerobic gram-negative rods and cocci isolation rate was high for irradiated individuals, and they were 64/25% and 100/80% for groups A/C and B/D, respectively. Recovery of aerobic and facultatively anaerobic gram-negative rods and cocci and Klebsiella pneumoniae subsp. pneumoniae in oral rinse samples were found to be significantly more prevalent in the irradiated subjects (groups A and B). Enterobacteriaceae were more frequently isolated from oral rinse samples of aged irradiated subjects (group B vs D, P<0.05), where the quantity of Citrobacter freundii (colony-forming units/ml oral rinse) was also significantly elevated. The isolation rate of aerobic and facultatively anaerobic gram-negative rods and cocci after hygienic care remained unchanged; 3 of 12 and 3 of 5 of the recalled subjects from groups A and B, respectively, harbored same aerobic and facultatively anaerobic gram-negative rods and cocci species. However, only two pairs of K. pneumoniae subsp. pneumoniae, sequentially isolated from same patients in group B, were found to be identical by pulsed-field gel electrophoresis. This may be due to reinfection of the microbes from the same source or permanent colonization. In conclusion, irradiation-induced xerostomia seems to favor frequent, repeated, transient intraoral colonization of aerobic and facultatively anaerobic gram-negative rods and cocci.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acinetobacter / classification
  • Adult
  • Age Factors
  • Aged
  • Bacterial Typing Techniques
  • Carcinoma / radiotherapy*
  • Case-Control Studies
  • Citrobacter / classification
  • Cohort Studies
  • DNA, Bacterial / analysis
  • Drug Resistance, Bacterial
  • Electrophoresis, Gel, Pulsed-Field
  • Enterobacter / classification
  • Escherichia / classification
  • Flavobacterium / classification
  • Follow-Up Studies
  • Genotype
  • Gram-Negative Aerobic Rods and Cocci / classification*
  • Gram-Negative Facultatively Anaerobic Rods / classification*
  • Humans
  • Klebsiella / classification
  • Klebsiella pneumoniae / classification
  • Middle Aged
  • Mouth / microbiology*
  • Mouth / radiation effects
  • Nasopharyngeal Neoplasms / radiotherapy*
  • Neisseria / classification
  • Oral Hygiene
  • Phenotype
  • Pseudomonas / classification
  • Statistics as Topic
  • Statistics, Nonparametric
  • Xerostomia / etiology
  • Xerostomia / microbiology*

Substances

  • DNA, Bacterial