Resistance profile and minimum inhibitory concentration versus minimum biofilm inhibitory concentration of biofilm positive Staphylococci
Notice bibliographique
Résumé
Background: Staphylococcal spp. are recognized as one of the most frequent causes of biofilm associated infections. In routine microbiology laboratories, standard method for testing antibiotic susceptibility is Kirby-Bauer disc diffusion method and minimum inhibitory concentration (MIC) which determine the antibiotic susceptibilities in planktonic phase. However, isolates capable of producing biofilm exist in biofilm state. Thus,antibiotics prescribed based on routine methods fail to eradicate biofilms thereby causing persistent infection and possible treatment failure. Thus, this work was designed to study prevalence of biofilm producing staphylococci, its resistance profile and to perform MIC versus MBIC (Minimum biofilm inhibitory concentration) in representative biofilm positive isolates. Methods and materials: 335 clinical isolates of staphylococci included in the study were screened for biofilm formation phenotypically by Congo red agar (CRA) and Tissue culture plate method (TCPM) followed by detection of biofilm genes (icaAD,aap,atlE) by PCR. Antibiotic susceptibility testing was done for biofilm positive isolates. MIC versus MBIC testing was performed for representative biofilm positive isolates for cefoxitin and vancomycin. MIC was done by broth microdilution and MBIC testing was performed using Calgary Biofilm Device. Results were interpreted according to CLSI guidelines,2015. Results: 77/335 (30%) staphylococcal isolates were biofilm positive of which S.haemolyticus (n = 35, 45.5%) was predominant followed by S. aureus (n = 27, 35.1%) and S.epidermidis (n = 15, 19.5%). By CRA, 22 (28.6%) isolates produced black colonies after 24 hours. By TCPM, 4 (5.2%), 1 (1.3%) & 49 (63.6%) isolates showed strong, moderate and weak biofilm production respectively. Overall, 77 isolates harboured biofilm genes (47aap,15atlE,15aap+atlE,5icaAD+aap+atlE).43/77 (55.8%)isolates were methicillin resistant. Highest resistance was found towards ciprofloxacin (74%) followed by erythromycin (70.1%),cotrimoxazole (65%) and pristinamycin (65%) respectively. MIC and MBIC were compared for 25 representative biofilm positive isolates. Cefoxitin MIC and MBIC ranged between 2–1024 μg/mL and 8–2048 μg/mL respectively. Vancomycin MIC and MBIC ranged between 0.5–8 μg/mL and 2–512 μg/mL respectively. Both cefoxitin and vancomycin MBIC values were 2–64 folds higher than their respective MIC. Conclusion: The present study documents biofilm producing capability in 30% of isolates. The antibiotic sensitivities of organisms in planktonic phase tested by MIC were significantly higher than for the same organism in their biofilm state as tested by MBIC. The results of the study questions the use of vancomycin as last resort antibiotic for biofilm-associated staphylococcal infections.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».