MICROBIOLOGICAL DIAGNOSIS OF THE SEVERE CHRONIC PERIODONTITIS

In total, 14 adult patients with severe chronic periodontitis were evaluated for the presence of associated anaerobic and aerobic bacteria. Subgingival plaque specimens from three pocket depths per patient were obtained. Microaerophilic and facultative anaerobic bacteria, probably involved in the periodontitis, were isolated in six (42.9%) patients. These were Gram negative species involving Aggregatibacter (Haemophilus) aphrophilus (14.3%), Haemophilus parainfluenzae (7.1%), Kingella denitrificans (7.1%) and Moraxella osloensis (7.1%) as well as Gram-positive species, including Arcanobacterium (Actinomyces) pyogenes (7.1%) and Rhodococcus equi (7.1%). Anaerobic microbiology was completed for 12 patients. Of them, suspected periodontopathogens were isolated in seven (58.3%) patients and comprised Prevotella intermedia (in 41.7% of the patients) and Porphyromonas gingivalis (25%) as well as Porphyromonas endodontalis (8.3%). Tannerella forsythia was detected by PCR in half of the 12 cases. In conclusion, the presence of periodontopathogens as well as other bacterial species of possible importance should be considered in the patients with severe chronic periodontitis.

Periodontal diseases are serious diseases in humans and, if untreated, can cause the tooth to loosen and then to be lost.Up to 30% of the adults have been reported to have periodontitis with presence of ≥3 teeth with pockets of ≥4 mm (Kumar et al., 2005).Chronic periodontitis have been considered to be chromic infections, involving anaerobic, microaerophilic and aerobic bacteria.Many putative periodontal pathogens have been extensively evaluated and involved Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Tannerella forsythia, Porphyromonas gingivalis, Porphyromonas endodontalis, Treponema denticola etc. (Kumar et al., 2003;Kumar et al., 2005).

AIM
The aim of this study was to assess the incidence and susceptibility patterns of the anaerobic and aerobic bacteria as periodontopathogens as well as other bacterial species of possible importance in the patients with severe chronic periodontitis.

MATERIAL AND METHODS
In total, 27 adult patients with severe chronic periodontitis were evaluated for the presence of associated anaerobic and aerobic bacteria.Of them, 22 patients were untreated and 5 were treated for the periodontitis.Anaerobic microbiology was performed to detect the growth of the suspected peiodondontopathogens such as P. intermedia, P. gingivalis and P. endodontalis, as well as the presence of T. forsythia by PCR.Additionally, the presence of nonintermedia pigmented Prevotella spp.(NIPPS), and Actinomyces odontolyticus (AO) spp.was evaluated.
Subgingival plaque specimens from three pocket depths per patient were obtained.The pocket depths were 3-5, 5-7 and >7 mm.For the first four patients, one subgingival pocket specimen per patient was taken for both aerobic and anaerobic microbiology.For the other patients, two subgingival pocket specimens per patient (one for aerobic and one for anaerobic microbiology) were taken with sterile paper-points (35Roeko).The specimens for anaerobic microbiology were placed in Stuart transport medium (BBL) or Portagerm (bio Merieux) and were sent to the laboratory within 1-2 h.
The pigmented anaerobes were subcultured and tested with DMACA indol dropper (BBL).
The isolated P. intermedia and P. gingivalis strains were tested for susceptibility to amoxicillin, metronidazole, clindamycin, azithromycin, tetracycline and ciprofloxacin with M.I.C.Evaluator (Oxoid, England) as well as with breakpoint susceptibility testing method (BST) as described previously (Boyanova et al., 2006).Actinomyces odontolyticus, Porphyromonas endodontalis and nonintermedia pigmented Prevotella strains (NIPPS) were additionally evaluated.The bacterial inoculum corresponded to 0.5 McFarland standard and the final inoculum was about 105 c.f.u. per spot (CLSI-NCCLS, 2004).When no growth was observed on the plate after 48 h of anaerobic incubation, the isolate was considered to be susceptible to the agent.Breakpoints for resistance were amoxicillin ≥2 mg/ L, metronidazole ≥32 mg/L, clindamycin ≥8 mg/L (CLSI-NCCLS, 2004), tetracycline >4, ciprofloxacin >1 mg/L, respectively, and azithromycin >2 mg/L.
All colonies from the non-selective anaerobic medium after 10-day-anaerobic-inculation were collected in PBS 1 mL to perform PCR for T. forsythia.T. forsythia-specific primers, which amplify a 641-bp amplicon from the 16 rRNA gene, were used (Sharma et al., 2005), (Table 1).
PCR products were analyzed by agarose (1%) gel electrophoresis and ethidium bromide staining.

Aerobic microbiology
The aerobic media used were: For the isolation of the pathogenic species Aggregatibacter actinomycetemcomitans and Aggregatibacter (Haemophilus) aphrophilus (commonly associated with periodontal disease), we used selective medium with vancomycin, nonselective chocolate agar (GC agar with 1% haemoglobin and 1% isovitalex) and blood agar, and the agar of McConkey served as a negative control.The selective medium contains brain heart infusion àãàð (BHIA), to 1 liter of which are added: 5 g yeast extract, 1.5 g sodium fumarate, 1g sodium formiate and 9 mg vancomycin.The medium favors the oral species of the genus Aggregatibacter.The specimens were then incubated for 48h in microaerophilic conditions.For identification of the isolates, we used BBL Crystal N/H and apiNH of bioMerieux, as well as ONP tests of PLIVA-Lachema.
The antimicrobial susceptibility testing was made by DDM (disk diffusion method) on Haemophilus test medium with antibiotic discs for the antimicrobials amoxicillin, trimetoprim/sulfamethoxazole, ceftriaxone, ciprofloxacin (Oxoid).The MIC determining was done for azithromycin and tetracycline by using Å-test strips (ÀB Biodisk, Solna, Sweden).

RESULTS
Anaerobic microbiology was completed for the 27 patients.Of them, Gram-negative pigmented anaerobic bacteria (P.intermedia, P. gingivalis, non-intermedia pigmented Prevotella spp.(NIPPS) and P. endodontalis, alone or in combinations) were isolated in 92.6% (25 of 27 patients), involving 90.9% (20 of 22 cases) of the untreated patients and all the five treated patients (Fig. 1).

Primers for T. forsythia Size
Tf -F 5'-GCGTATGTAACCTGCCCGCA-3', Tf -R 5'-TGCTTCAGTGTCAGTTATACCT-3' 641 bp P. intermedia was found in 37.0% (10 of 27 cases) of all patients, including 36.4% (8 of 22) untreated patients and two of five treated patients.P. gingivalis was detected in 25.9% (7 of 27) of all patients, including 31.8% (7 of 22) of the untreated subjects and in no specimen from treated patients.P. endodontalis was isolated from 11.1% (3 of 27 cases) of all patients, including 4.5% (1 of 22) of the specimens from untreated patients and two of the five specimens from treated patients.
Both P. intermedia and P. gingivalis/P.endodontalis were present in the specimens from five (four untreated and one treated) patients.
In the 22 untreated patients, P. intermedia and P.
gingivalis/P.endodontalis, alone or in combinations, were found in 31.8%(7 of 22 specimens) of the specimens from pocket depth 3-5 mm, 40.9% (9 of 22) of those from pocket depth 5-7 mm and in 50% (11 of 22) of those from pocket depth >7 mm (Table 4).In untreated patients, A. odontolyticus was detected in five specimens from pocket depth 3-5 mm, four specimens from pocket depth 5-7 mm and six specimens from pocket depth >7 mm.In treated patients, however, A. odontolyticus was found only in two specimens from pocket depth 3-5 mm.
In untreated patients, NIPPS were found in nine specimens from pocket depth 3-5 mm, four specimens from pocket depth 5-7 mm and five specimens from pocket depth >7 mm.
T. forsythia was detected by PCR in 44.4% (8 of 18 cases) of the patients evaluated, involving 50% (8 of 16) of the untreated patients and none of the two treated patients.Within the untreated patients, T. forsythia positive were 37.5% (6 of 16 cases) of the specimens from pocket depth 3-5 mm, 50% (8 of 16) of those from pocket depth 5-7 mm and in 37.5% (6 of 16 cases) of those from pocket depth >7 mm.
It is of note that two of the four strains of the pigmented anaerobic periodontopathogens (P.intermedia, P. gingivalis and P. endodontalis) from the three treated patients, were resistant to amoxicillin and were betalactamase positive.Both resistant strains belonged to the species P. intermedia.One P. intermedia strain from a treated patient acquired a secondary resistance to amoxicillin (the strain being susceptible to the agent before treatment and resistant after treatment).
The strains from the treated patients were susceptible to metronidazole (MICs, ≤8 mg/L), clindamycin (MICs, ≤2 mg/L), azithromycin (MICs, ≤2 mg/L) and ciprofloxacin (MICs, ≤1 mg/L).One patient' strain, which was tetracycline resistant (MIC, 8 mg/L), remained resistant after treatment with the same MIC concentration.Boutaga et al. (2007) have reported the real-time polymerase chain reaction (PCR) to be a very sensitive technique to detect bacterial periodontopathogens.Probably, the relatively low detection rate of Porphyromonas spp.(36.4%, 8 of 22 cases) in the untreated patients in the present study could be explained by the use of culture instead of PCR-based method as well as by the use of one specimen per patient for both aerobic and anaerobic microbiology laboratories for the first four patients (Table 3).

DISCUSSION
The incidence of P. intermedia in the present study was similar to those (10.5-55.5%)reported in the literature but was higher than that in the culture-based study of Salari & Kadkhoda (2004).In the present study, however, the detection of both P. gingivalis and P. endodontalis was lower than that by PCR-based methods but was higher than that performed with culture by Salari & Kadkhoda (2004).
Both P. intermedia and P. gingivalis/P.endodontalis per specimen were found only in one specimen from pocket depth 3-5 mm, one specimen from pocket depth 5-7 mm and in more (five) specimens from pocket depth >7 mm.The Gram-negative pigmented anaerobic periodontopathogens from untreated patients exhibited similar antibacterial susceptibility patterns to those in the study of Kulik et al. (2008), except for the higher resistance (40.0%) to tetracycline in the present study compared to 0-12.6% in the study of Kulik et al. (2008).
The acquisition of amoxicillin resistance in one P. intermedia strain, which was amoxicillin susceptible before treatment, is of clinical significance.
It is important that in untreated patients, more P. intermedia, P. gingivalis and P. endodontalis isolates were cultured from specimens of pocket depth >7 mm than in those with other depths (Table 4).

Table 4 . Distribution of anaerobic periodontopathogens according to the depth of the pocket.
* Only 16 untreated and two treated patients were evaluated for T. forsythia by PCR.