BackgroundChlorhexidine (CHX) is used in oral care products to help control dental plaque. In this study dental plaque bacteria were grown on media containing 2 μg/ml chlorhexidine gluconate to screen for bacteria with reduced CHX susceptibility. The isolates were characterized by 16S rRNA gene sequencing and antibiotic resistance profiles were determined using the disc diffusion method.ResultsThe isolates were variably resistant to multiple drugs including ampicillin, kanamycin, gentamicin and tetracycline. Two species, Chryseobacterium culicis and Chryseobacterium indologenes were able to grow planktonically and form biofilms in the presence of 32 μg/ml CHX. In the CHX and multidrug resistant C. indologenes we demonstrated a 19-fold up-regulation of expression of the HlyD-like periplasmic adaptor protein of a tripartite efflux pump upon exposure to 16 μg/ml CHX suggesting that multidrug resistance may be mediated by this system. Exposure of biofilms of these resistant species to undiluted commercial CHX mouthwash for intervals from 5 to 60 s indicated that the mouthwash was unlikely to eliminate them from dental plaque in vivo.ConclusionsThe study highlights the requirement for increased vigilance of the presence of multidrug resistant bacteria in dental plaque and raises a potential risk of long-term use of oral care products containing antimicrobial agents for the control of dental plaque.

Background:Urinary tract infection (UTI) is deemed the most prevalent infectious disease in that it has now touched the overall incidence of 18/1000 persons per year in the general population.Objectives:This study sought to determine the characteristics of isolates from patients with UTI and their susceptibility to commonly used antibiotics in Punjab, Pakistan.Patients and Methods:Totally, 1429 urine samples were analyzed from UTI patients for the isolation of uropathogens at Chughtai’s Lahore Lab, Lahore, Pakistan, during a period of 14 months. The antimicrobial susceptibility test was performed via the disc diffusion method for the isolates obtained from 392 (26%) positive cultures.Results:The highest percentage (67%) of isolates was from females in comparison to males (33%). The frequency of Escherichia coli was the highest (62%) in culture-positive urine samples, followed by E. faecalis (15%), Candida (14%), Pseudomonas (6%), Klebsiella spp. (1%), Proteus (1%), and Staphylococcus aureus (1%). E. coli was highly resistant to antimicrobial drugs, viz. cephalexin (95%), cephradine (95%), pipemidic acid (92%), amikacin (91%), and nalidixic acid (91%). Most of the routine β-lactam antibiotics like amoxicillin/clavulanic acid, ampicillin, and aztreonam were also ineffective against E. coli, with resistance rates of 84%, 84%, and 72%, correspondingly. This pathogen showed maximum susceptibility (97%) against three drugs, namely imipenem, meropenem, and cefoperazone. Piperacillin and fosfomycin also provided significant results against E. coli with respective susceptibility rates of 96% and 90%.Conclusions:Our results showed that broad-spectrum antibiotics such as imipenem, meropenem, fosfomycin, cefoperazone/sulbactam, and vancomycin would be the first line and the most effective drugs for the empirical treatment of urinary tract pathogens due to their higher resistance rates against other drugs like cephalexin, cephradine, ciprofloxacin, levofloxacin, and norfloxacin.

Actinomycetes are well known group of gram positive bacteria for their potential to produce antibiotics. This study sought to assess the ability of the selected actinomycetes to control biofilm forming bacteria isolated from different dental plaque samples. On the basis of morphological differences three out of ten different dental plaque bacterial isolates were selected for further study. These isolates were biochemically and genetically characterized and were identified as Acinetobacter schinndleri, Moraxella aci, and Bacillus cereus. Antibiotic resistant profile was measured through disc diffusion method and found that all three isolates were moderately sensitive to ofloxacin and erythromycin and resistant to trimethoprim. Antibacterial activity of ten different Streptomyces strains was assessed through an agar plug and well diffusion method against three dental biofilm forming bacteria. Two Streptomyces strains named as S. erythrogriseus and S. labedae showed good antibacterial activity against Moraxella and Acinetobacter strains. Ability of the four active antibiotic producing strains to inhibit biofilm formation was assessed using microtiter biofilm detection assay. It was found that biofilm forming ability of Acinetobacter and Moraxella was inhibited by S. labedae an antibiotic producing strain, while S. macrosporeus can only inhibit biofilm formation by B. cereus.

Mercury (Hg) pollution is a worldwide problem and increasing day by day due to natural and anthropogenic sources. In this study, mercury-resistant (HgR) bacterial isolates were isolated from industrial wastewater of Ittehad Chemicals Ltd., Kala Shah Kaku, Lahore, Pakistan. Out of 65 bacterial isolates, five isolates were screened out based on showing resistance at 30–40 μg/ml against HgCl2. Selected Hg-resistant bacterial isolates were characterized as Bacillus subtilis AA-16 (OK562835), Bacillus cereus AA-18 (OK562834), Bacillus sp. AA-20 (OK562833), Bacillus paramycoides AA-30 (OK562836), and Bacillus thuringiensis AA-35 (OK562837). B. cereus AA-18 showed promising results in the resistance of HgCl2 (40 μg/ml) due to the presence of merA gene. Scanning electron microscopy (SEM) analysis of immobilized B. cereus AA-18 showed the accumulation Hg on the cell surface. The inoculation of immobilized B. cereus AA-18 remediated 86% Hg of industrial wastewater up to 72 h at large scale (p < 0.05). In silico analysis showed structural determination of MerA protein encoded by merA gene of B. cereus AA-18 (OK562598) using ProtParam, Pfam, ConSurf Server, InterPro, STRING, Jpred4, PSIPRED, I-TASSER, COACH server, TrRosetta, ERRAT, VERIFY3D, Ramachandran plot, and AutoDock Vina (PyRx 8.0). These bioinformatics tools predicted the structural-based functional homology of MerA protein (mercuric reductase) associated with mer operon harboring bacteria involved in Hg-bioremediation system.