Public health is facing a new challenge due to the alarming increase in bacterial resistance to most of the conventional antibacterial agents. It has been found that only minor cell damage is caused when exposed to sub-lethal levels of antimicrobial. Biofilms can play an important role in producing resistance, which is developed to reservoirs of pathogens in the hospital and cannot be easily removed. The aim of this study was to test whether the sub-lethal dose of antibiotics can induce biofilm formation of P. aeruginosa following incubating in the presence and absence of chlorhexidine. Standard antibiotic-micro broth 96-flat well plates were used for determination of MIC and biofilm assay. The adherence degree of biofilm was determined by estimation of OD 630 nm values using ELISA reader. The mean 22 isolates of P. aeruginosa growing in culture with presence and absence of chlorhexidine, could exhibited the significant (p < 0.001) proportion of adherence followed incubation in sub minimal inhibitory concentrations (Sub-MIC) of cefotaxim, amoxicillin, and azithromycin in comparison with control (antibiotic-free broth), while the sub-MIC of ciprofloxacin revealed significant inhibition of biofilm. Conclusion: Incubating the isolates of P. aeruginosa to sub-MIC of antibiotics exhibited induction of biofilm in the presence of chlorhexidine.

Background Emerging worldwide in the past decade, there has been a significant increase in multidrug-resistant bacteria from serious nosocomial infections, especially carbapenemase-producing Gram-negative bacilli that have emerged worldwide. The objective of this study is to investigate carbapenem resistance in Gram-negative bacilli bacteria using phenotypic detection, antimicrobial resistance profiles and genotypic characterisation methods. Methods 200 Gram-negative bacilli isolates were collected from different clinical specimens. All clinical samples were exposed to isolation and identification of significant pathogens applying bacteriological examination and an automated Vitek-2 system. The isolates were subjected to susceptibility tests by the Vitek-2 automated system and those isolates that were resistant to beta-lactam drugs, including carbapenems, third-generation cephalosporines or cefoxitin, were selected for phenotyping using Carba plus disc system assay for detection of carbapenemase-producing isolates. These isolates were further confirmed by molecular detection. PCR was used for the detection carbapenem-resistant genes (OXA-48, IMP, NDM, VIM, and KPC). Results 110 (55%) of 200 Gram-negative bacilli were identified as beta-lactam-resistant isolates. The frequency of carbapenem-resistant isolates was calculated to be 30.9% (n = 34/110). A collection totalling 65/110 (59%) isolates were identified as carbapenemase producers by phenotypic method. Moreover, among the 65 carbapenemase-producing Gram-negative isolates with a positive phenotype-based result, 30 (46%), 20 (30%) and 18 (27%) isolates were positive for OXA-48, KPC and MBL enzymes, respectively, as well as the production of 27% of AmpC with porin loss. Tigecycline was the most effective antibiotic that affected 70% of MDR isolates, but high rates of resistance were detected to other tested antimicrobials. Of interest, a high incidence of MDR, XDR and PDR profiles were observed among all carbapenemase-producing isolates. 36% (24/65) of the tested isolates were MDR to 3 to 5 antimicrobial classes. 29% (17/65) of the recovered isolates were XDR to 6 to 7 antimicrobial classes. Alarmingly, 24% (16/65) of isolates displayed PDR to all the tested 8 antimicrobial classes. Genotype assay, including 53 phenotypically confirmed carbapenemase-producing isolates of Gram-negative bacilli, found 51(96%) isolates were harbouring one or more genes. The most common carbapenemase gene was bla NDM 83% (44/53) followed by bla OXA-48 75% (40/53), bla VIM 49% (26/53) and bla IMP 43% (23/53), while the gene bla KPC was least frequent 7% (4/53). 92% (46/51) of isolates were involved in the production of more than one carbapenemase gene. Conclusion This study demonstrated the emergence of carbapenemase-producing Gram-negative pathogens implicated in healthcare-related infections. Accurate identification of carbapenem-resistant bacterial pathogens is essential for patient treatment, as well as the development of appropriate contamination control measures to limit the rapid spread of pathogens. Tigecycline exhibited potent antimicrobial activity against MDR, XDR and PDR-producing strains that establish a threatening alert which indicates the complex therapy of infections caused by these pathogens.

Nanotechnology is being investigated for its potential to improve nanomedicine for human health. The purpose of this study was to isolate carbapenemase-producing Gram-negative bacilli (CPGB), investigate the presence of carbapenemase resistance genes, determine their antibiogram and ability to biosynthesise silver nanoparticles (Ag NPs), and estimate the antibacterial activity of Acinetobacter baumannii-biosynthesised Ag NPs on CPGB alone and in combination with antibiotics. A total of 51 CPGBs were isolated from various specimens in the study. The automated Vitek-2 system was used to identify and test these strains' antimicrobial susceptibilities. The carbapenemase resistance genes were identified using a polymerase chain reaction (PCR). Under the CPGB, A. baumannii could biosynthesise Ag NPs. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and field emission scanning electron were used to characterise Ag NPs. The antibacterial activity of Ag NP alone and in combination with antibiotics against CPGB was determined using the broth microdilution method, and their synergistic effect was determined using the checkerboard assay. blaNDM and blaOXA-48 were the most commonly reported, and 90% of the isolates produced multiple carbapenemase genes. Tigecycline proved to be the most effective anti-CPGB antibiotic. Isolates with more resistance genes were more resistant to antibiotics, and isolates with three genes (42%) had the most extensively drug-resistant patterns (38%). A significant relationship was discovered between genetic and antibiotic resistance patterns. Only A. baumannii produced Ag NPs out of all the isolates tested. Ag NPs with a size of 10 nm were confirmed by UV–visible spectroscopy, FT-IR, XRD, and TEM analysis. The Ag NPs were effective against CPGB, with minimum inhibitory concentrations ranging from 64 to 8 μg/ml on average. Surprisingly, the combination of Ag NPs and antibiotics demonstrated synergistic and partial synergistic activity (fractional inhibitory concentration between 0.13 and 0.56) against CPGB, as well as a significant reduction in antibiotic concentrations, particularly in the case of A. baumanii versus ceftriaxone (1024 to 4 μg/ml). The notable synergistic activity of Ag NPs with antibiotics represents a valuable nanomedicine that may find clinical application in the future as a combined remedy.

Objectives: Cathelicidin LL37 represents one of the chemical defence components of bladder epithelial cells that include antimicrobial peptides, which also shown to have an important role in the mucosal immunity of the urinary tract by preventing adhesion of bacteria. This study aimed to determine the killing efficacy of LL37 compared to anti-biofilm activity against Staphylococcus aureus and Escherichia coli. Methods:The 96-flat well microtiter plates were used for evaluation of killing rate by estimation of MIC-value to the clinical isolates of E. coli and S. aureus collected from patients with urinary tract infection. S. aureus ATCC 25923 and E.coli ATCC 25922 were investigated in this study. Biofilm formation on polystyrene surface was conducted by growing bacterial isolates on 96-flat well microtiter plates, stained with crystal violet. The bound bacteria were quantified by addition of ethanol 70% and measurement of the dissolved crystal violet absorbance at (OD 630 nm) using ELISA reader.Results: LL37 showed minimal inhibitory concentration (MIC) of 32 µg/ml against S. aureus and E. coli. The sub-MIC of LL37 was also able to eliminate about 31% and 34% of both S. aureus and E. coli, respectively. Anti-biofilm activity of LL37 showed biofilm inhibition at 1 µg/ml (1/32 MIC) to 16 µg/ml (1/2 MIC), which exhibited significant difference (p<0.001) against E. coli, whereas LL37 beyond 1 µg/ml showed significant inhibition (p<0.001) of biofilm against S. aureus. Conclusion:The cathelicidin LL37 can be used as a broad-spectrum anti-biofilm agent rather than killing agent. Bulgular: S. aureus ve E. coli'ye karşı LL37, minimum inhibitör konsantrasyonu (MİK) 32 µg/ml'de gösterildi. LL37'nin alt MİK değerleri ile sırasıyla S. aureus ve E. coli'nin % 31 ve % 34'nü ortadan kaldırmak mümkün oldu. LL37'nin anti-biyofilm aktivitesi 1 µg/ml (1/32 MİK)'dan 16 µg/ml (1/2 MİK)'da biyofilm inhibisyonu gösterdi ve E. coli'ye karşı da belirgin bir fark (p <0.001 ) ortaya koydu. LL37'nin ise 1 µg/ml'nin üzerinde S aureus'a karşı biyofilmi önemli ölçüde inhibe ettiği bulundu (p <0.001).Sonuç: Cathelicidin LL37 geniş spektrumlu anti-biyofilm ajan olarak öldürücü maddeler yerine kullanılabilir.

Introduction Extended spectrum beta lactamases (ESBL) enzymes were first described in Germany in 1983 from Klebsiella pneumonia. ESBL enzymes are usually plasmid mediated and gain broad resistance to cephalosporins: (cefotaxime, ceftazidime, ceftriaxone), and monobactams (aztreonam). 1 A new class of ESBL, called CTX-M enzymes, has emerged during late 1990 and early 2000s, which was widely detected among Escherichia coli (E. coli) isolates. These ESBL-producing E. coli are able to resist penicillins, cephalosporins and are found mostly in urinary tract infections (UTI). 2,3 ESBL-producing strains can also display multi-drug resistance (MDR), including resistance to aminoglycosides and fluoroquinolones. Therefore, therapeutic options for these strains are limited. 4-6 Continuous exposure of such bacterial strains to ß-lactams could induce mutation and production of new ß-lactamases, expand their activity even against the fourth generation cephalosporins. Thus, these new ß-lactamases are called extended spectrum ß-lactamases. 7 ESBL-producing Background and objective: Bacterial resistant to broad spectrum β-lactams, which is mediated by the extended spectrum beta lactamase enzyme, has emerged recently as increasing problem. Extended spectrum beta lactamase producing strains can also displaying multi-drug resistance. Thus, increased number of infections due to these strains is a public health issue associated with high morbidity, mortality, high health-care costs and prolonged hospitalization. Therefore, this study aimed to evaluate multi-drug resistance among extended spectrum beta lactamase producing E. coli causing urinary tract infections. Methods: A total of 400 mid-stream urine specimens were collected from patients with urinary tract infection. Disk diffusion agar method on Muller-Hinton agar plates was carried out. Double Disc Synergy Test was used for detection of extended spectrum beta lactamase producer. All the isolates that were screened out for extended spectrum beta lactamase production were also subjected to confirmation by using the Phenotypic Confirmatory Combination Disc Diffusion Test. Results: The urinary tract infection cases were mainly due to Gram negative bacteria (87%). E. coli was isolated from 195 (48%) specimens. Sixty isolates of E. coli (31%) were found to be extended spectrum beta lactamase producers. The resistance to antibiotics tested was significantly higher (P <0.001) among extended spectrum beta lactamase producing E. coli isolates compared with non-extended spectrum beta lactamase producing isolates. Conclusion: The prevalence of multi-drug resistance to the antibiotics among extended spectrum beta lactamase producing E. coli isolates was established. Imipenems are recommended for the treatment of serious infections caused by these organisms.