Molecular characterization of a multidrug-resistant/pandrug-resistant nosocomial polymicrobial infection with Klebsiella pneumoniae, Providencia rettgeri, and Acinetobacter baumannii from Rural Maharashtra, India.

The emergence of resistance against commonly used antibiotics has become a serious global concern. The rapid development of antibiotic resistance exhibited by Enterobacteriaceae has caused an increasing concern regarding untreatable bacterial infections. Here, we isolated four pathogens from a geriatric female patient who was hospitalized for a month with ventilator-associated pneumonia (VAP) and fever. The organisms isolated from the tracheal aspirates and urine included Klebsiella pneumoniae, pandrug-resistant Providencia rettgeri, and Acinetobacter baumannii. Resistome analysis indicated that the bacterial isolates from the polymicrobial infection were multiple-drug resitnat and pandrug resistant clones. Molecular characterization revealed presence of blaTEM-1 in K. pneumonaie, P. rettgeri and A. baumannii. The blaTEM-1 and blaNDM-1 genes were present in P. rettgeri and A. baumannii, whereas the blaTEM-1, blaNDM-1 and blaOXA-23 traits were present in A. baumannii isolates. The patient has died due to the unavailability of effective antimicrobial treatment for this drug-resistant polymicrobial infection.

Immunomodulatory Effect of Doxycycline Ameliorates Systemic and Pulmonary Inflammation in a Murine Polymicrobial Sepsis Model.

Acute lung injury is an inflammatory condition developed after severe sepsis in response to excessive secretion of pro-inflammatory cytokines. Doxycycline is widely reported to possess immunomodulatory activity through inhibition of various inflammatory pathways. Considering the broad spectrum of anti-inflammatory activity, protective effect of doxycycline was evaluated in clinically relevant murine polymicrobial sepsis model induced by caecal ligation and puncture (CLP). In this model, sepsis is accompanied with infection and therefore ceftriaxone at sub-protective dose was combined to retard the bacterial growth. Three hours after CLP challenge, mice were administered vehicle, ceftriaxone (100 mg/kg subcutaneously) alone and in combination with immunomodulatory dose of doxycycline (50 mg/kg, intraperitoneal) and survival were monitored for 5 days. Bacterial count in blood and peritoneal fluid along with cytokines [interleukin (IL)-6, IL-1ß, tumour necrosis factor (TNF)-α] and myeloperoxidase (MPO) in plasma and lung homogenate were measured at 18 h post-CLP. Plasma glutathione (GSH) was also determined. Doxycycline in presence of ceftriaxone improved survival of septic mice by significantly reducing the plasma and lung pro-inflammatory cytokines and MPO levels. It also increased plasma GSH levels. Doxycycline did not improve antibacterial effect of ceftriaxone in combination, suggesting that the protective effect of doxycycline was due to its immunomodulatory activity. Doxycycline in the presence of ceftriaxone demonstrated improved survival of septic mice by modulating the immune response.

In vitro activity of a novel antibacterial agent, levonadifloxacin, against clinical isolates collected in a prospective, multicentre surveillance study in India during 2016-18.

BACKGROUND: Levonadifloxacin is a novel antibiotic belonging to the benzoquinolizine subclass of fluoroquinolones with potent activity against MRSA and quinolone-resistant Staphylococcus aureus. IV levonadifloxacin and its oral prodrug alalevonadifloxacin have recently been approved in India for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) including diabetic foot infections. OBJECTIVES: To investigate the in vitro activity of levonadifloxacin against contemporary clinical isolates collected from multiple tertiary care hospitals across India in the Antimicrobial Susceptibility Profiling of Indian Resistotypes (ASPIRE) surveillance study. METHODS: A total of 1376 clinical isolates, consisting of staphylococci (n = 677), streptococci (n = 178), Enterobacterales (n = 320), Pseudomonas aeruginosa (n = 140) and Acinetobacter baumannii (n = 61), collected (2016-18) from 16 tertiary hospitals located across 12 states in India, were included in the study. The MICs of levonadifloxacin and comparator antibiotics were determined using the reference agar dilution method and broth microdilution method. RESULTS: Levonadifloxacin exhibited potent activity against MSSA (MIC50/90: 0.5/1 mg/L), MRSA (MIC50/90: 0.5/1 mg/L) and levofloxacin-resistant S. aureus (MIC50/90: 1/1 mg/L) isolates. Similarly, potent activity of levonadifloxacin was also observed against CoNS including MDR isolates (MIC50/90: 1/2 mg/L). Against Streptococcus pneumoniae, levonadifloxacin (MIC50/90: 0.5/0.5 mg/L) showed superior activity compared with levofloxacin (MIC50/90: 1/2 mg/L). Among levofloxacin-susceptible Enterobacterales, 80.6% of isolates were inhibited at ≤2 mg/L levonadifloxacin. CONCLUSIONS: Levonadifloxacin displayed potent activity against contemporary MRSA and fluoroquinolone-resistant staphylococcal isolates, thus offering a valuable IV as well as an oral therapeutic option for the treatment of ABSSSIs. Furthermore, levonadifloxacin exhibited a broad-spectrum activity profile as evident from its activity against streptococci and levofloxacin-susceptible Gram-negative isolates.

In vitro bactericidal activity of levonadifloxacin (WCK 771) against methicillin- and quinolone-resistant Staphylococcus aureus biofilms.

PURPOSE: Staphylococcus aureus causes a wide range of infections, such as endocarditis, pneumonia, osteomyelitis, skin and soft tissue infections, and implant/in-dwelling device-related infections. S. aureus poses a significant challenge to clinicians because of its ability to rapidly acquire multi-drug resistance and quickly progress into a recurrent, chronic infection by biofilm formation. Levonadifloxacin (WCK 771) is a novel broad-spectrum antibacterial agent (it recently completed a phase 3 trial in India) with a differentiated mechanism of action involving high affinity to staphylococcal DNA gyrase, and is active against multi-drug-resistant (MDR) S. aureus, including those that are resistant to quinolones. The present study investigated the bactericidal activity of levonadifloxacin against biofilm-embedded S. aureus clinical isolates in comparison with other anti-S. aureus drugs. METHODOLOGY: The bactericidal activity of levonadifloxacin and comparator drugs such as vancomycin, linezolid and daptomycin was evaluated against planktonic and biofilm-encapsulated recent methicillin- and quinolone-resistant S. aureus clinical isolates using time-kill, biofilm eradication and scanning electron microscopy analysis. RESULTS: Levonadifloxacin displayed a consistent ≥90 % bacterial kill rate against biofilm-embedded organisms, while vancomycin and linezolid displayed variable activity and daptomycin did not show any activity. Scanning electron microscopy images further confirmed the efficacy of levonadifloxacin against biofilm, showing the disruption of biofilm structure and a corresponding reduction in the viable bacterial count. CONCLUSION: These results show that levonadifloxacin has an improved bactericidal effect on biofilm-embedded quinolone-resistant S. aureus and meticillin-resistant S. aureus, and that it can be a promising treatment option for such infections.