Inhibition and Reduction of Biofilm Production along with Their Antibiogram Pattern among Gram-Negative Clinical Isolates.

Background: Bacterial biofilm is a significant virulence factor threatening patients, leading to chronic infections and economic burdens. Therefore, it is crucial to identify biofilm production, its inhibition, and reduction. In this study, we investigated biofilm production among Gram-negative isolates and assessed the inhibitory and reduction potential of ethylene diamine tetra acetic acid (EDTA) and dimethyl sulfoxide (DMSO) towards them. In addition, we studied the antimicrobial resistance pattern of the Gram-negative isolates. Methods: Bacterial isolation and identification was done using standard microbiological techniques, following the Clinical and Laboratory Standards Institute (CLSI) guideline, 28th edition. The Kirby-Bauer disk diffusion method was used to determine the antibiotic susceptibility pattern of the isolates, and ß-lactamase production was tested via the combination disk method. Biofilm formation was detected through the tissue culture plate (TCP) method. Different concentrations of EDTA and DMSO were used to determine their inhibitory and reduction properties against the biofilm. Both inhibition and reduction by the various concentrations of EDTA and DMSO were analyzed using paired t-tests. Results: Among the 110 clinical isolates, 61.8% (68) were found to be multidrug resistant (MDR). 30% (33/110) of the isolates were extended-spectrum ß-lactamase (ESBL) producers, 14.5% (16/110) were metallo-ß-lactamase (MBL), and 8% (9/110) were Klebsiella pneumoniae carbapenemase (KPC) producers. Biofilm formation was detected in 35.4% of the isolates. Biofilm-producing organisms showed the highest resistance to antibiotics such as cephalosporins, chloramphenicol, gentamicin, and carbapenem. The inhibition and reduction of biofilm were significantly lower (p < 0.05) for 1 mM of EDTA and 2% of DMSO. Conclusion: Isolates forming biofilm had a higher resistance rate and ß-lactamase production compared to biofilm nonproducers. EDTA and DMSO were found to be potential antibiofilm agents. Hence, EDTA and DMSO might be an effective antibiofilm agent to control biofilm-associated infections.

Phenotypic detection of methicillin resistance, biofilm production, and inducible clindamycin resistance in Staphylococcus aureus clinical isolates in Kathmandu, Nepal.

INTRODUCTION: Methicillin resistance, inducible clindamycin resistance (ICR), biofilm production, and increased minimum inhibitory concentration (MIC) of vancomycin in Staphylococcus aureus are major causes of antibiotic treatment failure and increased morbidity and mortality. The surveillance of such isolates and the study of their antimicrobial pattern are essential in managing the infections caused by these isolates. This study aimed to determine methicillin resistance, biofilm production, and ICR in S. aureus isolates from a tertiary care hospital in Kathmandu, Nepal. MATERIALS AND METHODS: A total of 217 S. aureus isolated from different samples were processed following standard laboratory procedures. Antibiotic susceptibility testing was performed by the Kirby-Bauer disk diffusion technique. Methicillin-resistant S. aureus (MRSA) were identified by the cefoxitin disk diffusion test, and biofilm producers were examined using the microtiter plate technique. D-test and E-test were performed to determine inducible clindamycin resistance and minimum inhibitory concentration of vancomycin, respectively. RESULTS: Among the 217 S. aureus isolates, 78.3% were multidrug-resistant (MDR), 47.0% were MRSA, 62.2% were biofilm producers, and 50.7% showed ICR. All MRSA isolates exhibited MIC levels of vancomycin within the susceptible range. Biofilm producers and MRSA isolates showed elevated antimicrobial resistance. MRSA was significantly associated with MDR. Biofilm-producing and multidrug-resistant MRSA isolates showed significantly higher MIC levels of vancomycin (p = 0.0013 and < 0.0001, respectively), while ICR was significantly higher in MDR (p = 0.0001) isolates. CONCLUSION: High multidrug resistance, MRSA, and ICR in this study call for routine evaluation of antibiotic susceptibility patterns of S. aureus. Vancomycin can be used to treat serious staphylococcal infections. Clindamycin should be prescribed only after performing the D-test. Drugs like teicoplanin, chloramphenicol, doxycycline, amikacin, and levofloxacin can treat MRSA infections.

Nasal Carriage of Methicillin-Resistant Staphylococcus aureus among Healthcare Workers in a Tertiary Care Hospital, Kathmandu, Nepal.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common causes of nosocomial infections. One of the potential risk factors for nosocomial staphylococcal infections is colonization of the anterior nares of healthcare workers (HCWs). Our study aimed to determine the rate of nasal carriage MRSA among HCWs at Manmohan Memorial Medical College and Teaching Hospital, Kathmandu. METHODS: Two hundred and thirty-two nasal swabs were collected from HCWs of Manmohan Memorial Medical College and Teaching Hospital, Kathmandu, Nepal, within six months (February 2018-July 2018). Nasal swabs were cultured, and S. aureus isolates were subjected to the antimicrobial susceptibility test by the modified Kirby-Bauer disc diffusion method. MRSA and iMLSB (inducible macrolide lincosamide streptogramin B) resistance was screened using the cefoxitin disc (30 µg) and D-test (clindamycin and erythromycin sensitivity pattern), respectively, following CLSI (Clinical and Laboratory Standard Institute) guidelines. Risk factors for MRSA colonization were determined using the chi-square test considering the p value ˂0.05 as significant. RESULTS: A total of 34/232 (14.7%) S. aureus were isolated, out of which 12 (35.3%) were MRSA. The overall rate of nasal carriage MRSA among HCWs was 5.2% (12/232). Colonization of MRSA was higher in males (8.7%) than in females (4.3%). MRSA colonization was found to be at peak among the doctors (11.4%). HCWs of the postoperative ward were colonized highest (18.2%). All MRSA isolates were sensitive to linezolid and tetracycline. iMLSB resistance was shown by 7(20.6%) of the isolates. MRSA strains showed higher iMLSB resistance accounting for 33.3% (4/12) in comparison to methicillin-susceptible strains with 13.6% (3/22). Smoking was found to be significantly associated with MRSA colonization (p=0.004). CONCLUSION: Rate of nasal carriage MRSA is high among HCWs and hence needs special attention to prevent HCW-associated infections that may result due to nasal colonization.