In vitro photoinactivation effectiveness of a portable LED device aimed for intranasal photodisinfection and a photosensitizer formulation comprising methylene blue and potassium iodide against bacterial, fungal, and viral respiratory pathogens.

Antimicrobial photodynamic therapy (aPDT) can be a viable option for management of intranasal infections. However, there are light delivery, fluence, and photosensitizer-related challenges. We report in vitro effectiveness of an easily fabricated, low-cost, portable, LED device and a formulation comprising methylene blue (MB) and potassium iodide (KI) for photoinactivation of pathogens of the nasal cavity, namely, methicillin-resistant Staphylococcus aureus, antibiotic-resistant Klebsiella pneumoniae, multi-antibiotic-resistant Pseudomonas aeruginosa, Candida spp., and SARS-CoV-2.In a 96-well plate, microbial suspensions incubated with 0.005% MB alone or MB and KI formulation were exposed to different red light (~ 660 ± 25 nm) fluence using the LED device fitted to each well. Survival loss in bacteria and fungi was quantified using colony-forming unit assay, and SARS-CoV-2 photodamage was assessed by RT-PCR.The results suggest that KI addition to MB leads to KI concentration-dependent potentiation (up to ~ 5 log10) of photoinactivation in bacteria and fungi. aPDT in the presence of 25 or 50 mM KI shows the following photoinactivation trend; Gm + ve bacteria > Gm - ve bacteria > fungi > virus. aPDT in the presence of 100 mM KI, using 3- or 5-min red light exposure, results in complete eradication of bacteria or fungi, respectively. For SARS-CoV-2, aPDT using MB-KI leads to a ~ 6.5 increase in cycle threshold value.The results demonstrate the photoinactivation effectiveness of the device and MB-KI formulation, which may be helpful in designing of an optimized protocol for future intranasal photoinactivation studies in clinical settings.

In vitro activity of daptomycin & linezolid against methicillin resistant Staphylococcus aureus & vancomycin resistant enterococci isolated from hospitalized cases in Central India.

BACKGROUND & OBJECTIVES: Growing incidence of methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enteroccoci (VRE) is posing a therapeutic problem due to limited drug options. Therefore, the present study was undertaken to check susceptibility of MRSA and VRE isolates against new antimicrobials such as daptomycin and linezolid. METHODS: A total of 586 Gram-positive isolates comprising 442 S. aureus and 144 enterococci isolated from hospitalized cases included in the study, were subjected to in vitro antimicrobial susceptibility testing by disc diffusion method. One hundred twenty four enterococci obtained from rectal swabs of neonates were also included. Minimum inhibitory concentration (MIC) was determined for daptomycin, linezolid, vancomycin and teicoplanin against 50 each isolates of MRSA and VRE by E strip. RESULTS: Among the staphylococci, 326 (73.85%) isolates were MRSA. MIC for vancomycin and teicoplanin among MRSA was ≤ 3 µg/ml. MIC for daptomycin among MRSA was found to be in the range of 0.064-1.5 µg/ml. Percentage of VRE among clinical samples was 14.29 per cent while it was 47.06 per cent among enterococci from rectal swabs of neonates. MIC was >256 µg/ml for vancomycin among VRE and was associated with van A genotype. MIC range for daptomycin among VRE was 0.38-3 µg/ml. MIC for linezolid among MRSA and VRE was in the range of 0.25 to 1 and 0.38 -1.5 µg/ml, respectively. INTERPRETATION & CONCLUSIONS: The present study showed a rise in MIC to vancomycin for sizable number of MRSA and growing percentage of VRE at our centre. Daptomycin and linezolid showed 100 per cent activity against MRSA and VRE.

Augmentation in zone of inhibition of cefoperazone/cefoperazone+ sulbactum compares well with the clinical laboratory standard institute standard extended spectrum beta-lactamase detection method as well as the polymerase chain reaction method.

BACKGROUND: With increased prevalence of extended spectrum beta-lactamase (ESBL) in hospital practice globally, reporting of extended spectrum beta-lactamase along with drug susceptibility test is expected from clinical microbiology laboratory. The aim was to evaluate cefoperazone and cefoperazone+sulbactum disc for phenotypic detection of extended spectrum beta-lactamase among E. coli and Klebsiella spp. isolates. METHODOLOGY: A total of 948 clinical specimens were analysed which included 496 E. coli and 392 Klebsiella pneumoniae. For confirmation of extended spectrum beta-lactamase ceftazidime/ceftazidime+clavulanidc acid and cefotaxime/ cefotaxime+clavulanic acid discs were used as recommended by Clinical Laboratory Standard Institute (CLSI). Simultaneously randomly selected 100 isolates, each of E. coli and Klebsiella spp. were identified for extended spectrum beta-lactamase genes coding for the TEM, SHV and CTX by polymerase chain reaction (PCR). The results were compared with cefoperazone/cefoperazone+sulbactum disc diffusion method. RESULT: Phenotypic characterization identified a high extended spectrum beta-lactamase rate. Four hundred out of 496 (80.64%) E. coli and 392 out of 452 Klebsiella spp.(86.7%) were positive for extended spectrum beta-lactamase by the Clinical Laboratory Standard Institute method. The increase in zone size of cefoprazone/cefoperazone+sulbactum (≥ 5 mm) was seen for all the isolates of E. coli and Klebsiella spp. which were confirmed as extended spectrum beta-lactamase by Clinical Laboratory Standard Institute as well as polymerase chain reaction (PCR) method. CONCLUSION: cefoperazone/cefoperazone+sulbactum disc diffusion showed 100% concordance with extended spectrum beta-lactamase detection by ceftazidime/ ceftazidime+clavulanidc cefotaxime/cefotaxime+clavulanic acid disc diffusion method and polymerase chain reaction.

Ciprofloxacin therapy for typhoid fever needs reconsideration.

Outbreaks of multidrug-resistant Salmonella enterica serotype Typhi in the Indian subcontinent in the late 1980s resulted in the failure of conventional drugs, and ciprofloxacin became the firstline drug to treat enteric fever. However, reduced susceptibility to ciprofloxacin, reported widely since 1994, has posed a therapeutic difficulty. The aim of the present work was to review the situation of drug resistance among S. enterica serotype Typhi in central India from 1988 to 2005. A minimum inhibitory concentration (MIC) study for ciprofloxacin was carried out by the agar dilution method on 314 stock cultures preserved since 1988. The MIC for ciprofloxacin was < or = 0.125 mg/l for the 50 isolates isolated during 1989-1994, but during 1998-1999, 60% of the 50 isolates showed MIC > 0.125 mg/l, while in 2002-2003, 82.5 % of the 97 isolates had MIC > 0.125 mg/l and 35% had MIC > 1 mg/l (high-level resistance). In 2004-2005, 88.2% of the 77 isolates had MIC > 0.125 mg/l and 15% had MIC > 1 mg/l (high-level resistance). Sixty-four isolates showing MIC > 1 mg/l with the agar dilution method were also checked by Epsilometer test (E-test, AB Biodisk, Solna, Sweden). Based on the data, it is suggested to withdraw ciprofloxacin as a therapeutic agent for enteric fever. Fortunately, multiple drug resistance, with concurrent resistance to chloramphenicol, cotrimoxazole, and ampicillin, which had reached more than 90% in 1990-1991, started declining over the years and was as low as 5.6% in 2004-2005. According to these observations, older drugs such as chloramphenicol, cotrimoxazole, and ampicillin could be recalled to treat enteric fever.

Practical limitations of disinfection of body fluid spills with 10,000 ppm sodium hypochlorite (NaOCl).

The purpose of this study was to monitor disinfection with 10,000 ppm sodium hypochlorite for decontamination of common hospital spills. Simulated spills deliberately contaminated with 10(8) bacterial challenges were used for the study. Results showed greater than 5 log reduction in the challenge bacteria for all spills (serum, pus, sputum, csf, ascitic fluid, urine, and stool) except blood. Disinfection was satisfactory for blood contaminated with gram-negative bacteria, but not for staphylococci. As a practical procedure, surfaces contaminated from gross spillage of human body fluids should first be contained with absorbent materials, then disinfected with hypochlorite.