Antibiotic resistance and capacity for biofilm formation of different bacteria isolated from endodontic infections associated with root-filled teeth.
BACKGROUND
To date, a variety of microbial species have been isolated from endodontic infections. However, endodontic clinical bacterial isolates have not been sufficiently characterized with regard to their capacity for antibiotic resistance and biofilm formation. In this study, antibiotic resistance and biofilm formation of 47 different aerobic and anaerobic bacterial isolates, belonging to 32 different species previously isolated from infected filled root canals, were studied.


METHODS
Antibiotic sensitivity to 11 antibiotics including penicillin G, amoxicillin, clindamycin, gentamicin, vancomycin, tetracycline, doxycycline, fosfomycin, rifampicin, ciprofloxacin, and moxifloxacin was tested using the standardized Etest method (Bio Merieux, Marcy-1'Etoile, France). The antibiotic sensitivity of 4 control strains was also estimated in parallel. Additionally, the capacity to form biofilms was quantified using the microtiter plate test.


RESULTS
Different aerobic and anaerobic bacterial species were either resistant against a number of antibiotics or showed high minimal inhibitory concentrations against clinically relevant antibiotics. Five aerobic and 2 anaerobic isolates, including Enterococcus faecalis, Streptococcus mutans, Lactobacillus fermentum, Actinomyces naeslundii, Actinomyces viscosus, Prevotella buccae, and Propionibacterium acidifaciens, were characterized as being high biofilm producers, whereas 8 aerobic and 3 anaerobic isolates were found to be moderate biofilm producers. Most isolates with resistance or markedly high minimal inhibitory concentration values were also either moderate biofilm producers or high biofilm producers.


CONCLUSIONS
These results suggest that the clinical significance of endodontic infections could include that they serve as a reservoir for antibiotic resistance. Furthermore, endodontic treatment should consider the adhesion and biofilm formation by a variety of bacteria.
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany. Electronic address: ali.al-ahmad@uniklinik-freiburg.de.
Ali
A
Al-Ahmad
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany.
Hawnaz
H
Ameen
Department of Hygiene and Microbiology, Albert-Ludwigs-University, Freiburg, Germany.
Klaus
K
Pelz
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany.
Lamprini
L
Karygianni
Department of Hygiene and Microbiology, Albert-Ludwigs-University, Freiburg, Germany.
Annette
A
Wittmer
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany.
Annette C
AC
Anderson
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany.
Bettina
B
Spitzmüller
Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Freiburg, Germany.
Elmar
E
Hellwig
D000190:Actinomyces / Q000187:drug effects / Q000502:physiology; D016924:Actinomyces viscosus / Q000187:drug effects / Q000502:physiology; D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms; D002939:Ciprofloxacin / Q000494:pharmacology; D002981:Clindamycin; D003788:Dental Pulp Diseases / Q000382:microbiology*; D004318:Doxycycline / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000502:physiology*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000502:physiology; D024841:Fluoroquinolones / Q000494:pharmacology; D005578:Fosfomycin / Q000494:pharmacology; D005839:Gentamicins / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000502:physiology*; D006094:Gram-Positive Bacteria / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D052197:Limosilactobacillus fermentum / Q000187:drug effects / Q000502:physiology; D000077266:Moxifloxacin; D010400:Penicillin G / Q000494:pharmacology; D010403:Penicillin Resistance; D018720:Prevotella / Q000187:drug effects / Q000502:physiology; D011424:Propionibacterium / Q000187:drug effects / Q000502:physiology; D012293:Rifampin / Q000494:pharmacology; D013295:Streptococcus mutans / Q000187:drug effects / Q000502:physiology; D013753:Tetracycline Resistance; D019553:Tooth, Nonvital / Q000382:microbiology*; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D005839:Gentamicins; D005578:Fosfomycin; D002981:Clindamycin; D002939:Ciprofloxacin; D000658:Amoxicillin; D004318:Doxycycline; D010400:Penicillin G; D000077266:Moxifloxacin; D012293:Rifampin
Antibiotic resistance; apical periodontitis; biofilm; endodontic infection