Bacterial Sensitivity To Chlorhexidine and Povidone-Iodine Antiseptics Over Time: A Systematic Review and Meta-Analysis of Human-Derived Data

Background Surgical site infection (SSI) is the most common complication of surgery, increasing healthcare costs and hospital stay. Chlorhexidine (CHX) and povidone-iodine (PVI) are used for skin antisepsis, minimising SSIs. There is increasing concern of developing resistance to topical biocides, though clinical implications remain unclear. Outcomes: Determining whether the Minimum Bactericidal Concentration (MBC) for topical preparations of CHX or PVI have changed over time, in microbes relevant to SSI. Methods We included studies reporting the mean bactericidal concentration (MBC) of laboratory and clinical isolates of common microbes to CHX and PVI. Excluding non-human samples and studies using antimicrobial solvents or mixtures with other active substances. MBC was pooled in random effects meta-analyses. Change in MBC over time was explored using meta-regression. Results 79 studies were including, analysing 6218 microbes over 45 years. Most used CHX (93%), with insufficient data for meta-analysis of PVI. There was no change in MBC of CHX to Staphylococci (β 0.12 [-1.13, 1.37]; I2 99%) or Streptococci (β 0.13 [-0.35, 0.62]; I2 97%). Conclusions There is no evidence of reduced susceptibility of common SSI-causing microbes to CHX over time. Providing reassurance that the worldwide guidance that CHX should remain the first-choice agent for surgical skin antisepsis.

Bacterial Sensitivity to Chlorhexidine and Povidone-Iodine Antiseptics Over Time: A Systematic Review and Meta-Analysis of Human-Derived Data

Background: Surgical site infection (SSI) is the most common complication of surgery, increasing healthcare costs and hospital stay. Topical biocides such as chlorhexidine (CHX) and povidone-iodine (PVI) are used for skin antisepsis to minimise SSIs. There is an increasing concern of developing resistance to topical biocides, however the clinical implications of this remains unclear. Outcomes: The objective of this review was to determine whether the Minimum Bactericidal Concentration (MBC) for topical preparations of CHX or PVI have changed over time, in microbes relevant to SSI. Methods: We searched for studies which reported the mean bactericidal concentration (MBC) of laboratory and clinical isolates of common SSI causing microbes to CHX and PVI. We excluded samples derived from non-humans and studies using antimicrobial solvents or mixtures of biocides with other active substances. MBC was pooled in random effects meta-analyses and change in MBC over time was explored using meta-regression. Results: 79 studies were including, analysing 6218 microbes between 1976 and 2021. Most studies used CHX (93%) and there was insufficient data for meta-analysis of PVI. Enterobacteriales had the highest MBC for CHX (20 mg/L [95% CI 14, 25]; I 2 95%) whilst MRSA had the lowest (3 mg/L [95% CI 1, 2]; I 2 93%). There was no change in MBC of CHX to Staphylococci (β 0.12 [-1.13, 1.37]; I 2 99%) or Streptococci (β 0.13 [-0.35, 0.62]; I 2 97%). Conclusions: There is no evidence of change in susceptibility of common SSI-causing microbes to CHX over time. This study provides reassurance that the worldwide guidance that CHX should remain the first-choice agent for skin asepsis prior to surgery.

Phase separation in the outer membrane of Escherichia coli

Gram-negative bacteria are surrounded by a protective outer membrane (OM) with phospholipids in its inner leaflet and lipopolysaccharides (LPS) in its outer leaflet. The OM is also populated with many β-barrel outer-membrane proteins (OMPs), some of which have been shown to cluster into supramolecular assemblies. However, it remains unknown how abundant OMPs are organized across the entire bacterial surface and how this relates to the lipids in the membrane. Here, we reveal how the OM is organized from molecular to cellular length scales, using atomic force microscopy to visualize the OM of live bacteria, including engineered Escherichia coli strains and complemented by specific labeling of abundant OMPs. We find that a predominant OMP in the E. coli OM, the porin OmpF, forms a near-static network across the surface, which is interspersed with barren patches of LPS that grow and merge with other patches during cell elongation. Embedded within the porin network is OmpA, which forms noncovalent interactions to the underlying cell wall. When the OM is destabilized by mislocalization of phospholipids to the outer leaflet, a new phase appears, correlating with bacterial sensitivity to harsh environments. We conclude that the OM is a mosaic of phase-separated LPS-rich and OMP-rich regions, the maintenance of which is essential to the integrity of the membrane and hence to the lifestyle of a gram-negative bacterium.

Overview of Pathogens causing Nosocomial Infections in Various Wards of a Tertiary Health Care Hospital and their Antimicrobial Susceptibility Pattern - A Prospective Surveillance Study

The major problem encountered in recent days due to the advent of emerging antimicrobial resistance strains is Hospital Acquired Infections (HAIs). The spread of HAI is mainly through the hospital staff and the hospital settings’ inanimate surfaces. The study includes the surveillance of hospital surfaces, including wards and ICUs, by taking swabs dipped in normal saline. Pseudomonas aeruginosa (53.8%) was found to be the most common pathogen isolated, followed by Klebsiella species (18%), Methicillin-Sensitive Staphylococcus aureus (16%), Coagulase-Negative Staphylococci (6%), Methicillin-Resistant Staphylococcus aureus (3%). The widespread presence of bacterial sensitivity to antimicrobials and the modifications insensitivity forms the basis for designing antibacterial therapy’s practical recommendations and rational use of antimicrobials. Proper display of all Information, Education, and Communication (IEC) materials at appropriate places play a significant role in preventing nosocomial infections. Audiovisual aids and training to the staff play utmost importance in preventing the spread of HAIs. All these can reduce the occurrence and outbreak of nosocomial conditions. Overall, these minimize health care costs.

Antibacterial Residue Excretion via Urine as an Indicator for Therapeutical Treatment Choice and Farm Waste Treatment

Many of the infectious diseases that affect livestock have bacteria as etiological agents. Thus, therapy is based on antimicrobials that leave the animal’s tissues mainly via urine, reaching the environment through slurry and waste water. Once there, antimicrobial residues may lead to antibacterial resistance as well as toxicity for plants, animals, or humans. Hence, the objective was to describe the rate of antimicrobial excretion in urine in order to select the most appropriate molecule while reducing harmful effects. Thus, 62 pigs were treated with sulfamethoxypyridazine, oxytetracycline, and enrofloxacin. Urine was collected through the withdrawal period and analysed via LC-MS/MS. Oxytetracycline had the slowest rate of degradation (a half-life time of 4.18 days) and the most extended elimination period in urine (over 2 months), followed by enrofloxacin (a half-life time of 1.48 days, total urine elimination in ca. 3 weeks) and sulfamethoxypyridazine (a half-life time of 0.49 days, total urine elimination in ca. 1 week). Bacterial sensitivity and recommendations for responsible use are limiting when selecting the treatment. Nevertheless, with similar effectiveness, sulfamethoxypyridazine would be the choice, as waste treatment would only need to be implemented for 1 week after treatment. Thus, more in-depth knowledge regarding antibacterial elimination would improve resource management, while protecting animals and consumers’ health.

The Shift of Bacterial Sensitivity with Antibiotics in Acute Tonsillitis

Background: The infection of tonsil may occur primarily or secondarily as a result of upper respiratory tract infection, usually preceded by a viral infection. Bacterial tonsillitis is most commonly caused by Streptococcus pyogenes. Penicillin remains the treatment of choice for S. pyogenes tonsillitis. The present study aimed to identify the bacterial pathogen in acute tonsillitis and their sensitivity to antibiotics. Material and Methods: This prospective study was conducted in the Department of Otolaryngology and Head & Neck Surgery and Department of Microbiology, Gandaki Medical College, Pokhara Nepal from January 2018 to January 2019. Ninety-six patients who presented with acute tonsillitis and admitted in the hospital were included in the study. Results: The commonest age group of acute tonsillitis was found to be between 21-30 years. S. pyogenes was the commonest isolate 32(33.3%) followed by S. aureus 19(19.8%). Streptococcus pyogenes was sensitive to Ampicillin (65.6%) and Cloxacillin (68.7%) while the isolates were more sensitive to levofloxacin and doxycycline. Carbapenem were found to be most effective drugs for intravenous treatment. Conclusion: The most common bacterial isolates were Streptococcus pyogenes. The sensitivity of organism shift from ampicillin group to fluroquinolones and tetracycline. Identification of bacterial isolates and their antibiotics sensitivity patterns could prevent resistance of bacteria to drugs and help in the proper management of acute tonsillitis.

Osmotic stress and vesiculation as key mechanisms controlling bacterial sensitivity and resistance to TiO2 nanoparticles

Toxicity mechanisms of metal oxide nanoparticles towards bacteria and underlying roles of membrane composition are still debated. Herein, the response of lipopolysaccharide-truncated Escherichia coli K12 mutants to TiO2 nanoparticles (TiO2NPs, exposure in dark) is addressed at the molecular, single cell, and population levels by transcriptomics, fluorescence assays, cell nanomechanics and electrohydrodynamics. We show that outer core-free lipopolysaccharides featuring intact inner core increase cell sensitivity to TiO2NPs. TiO2NPs operate as membrane strippers, which induce osmotic stress, inactivate cell osmoregulation and initiate lipid peroxidation, which ultimately leads to genesis of membrane vesicles. In itself, truncation of lipopolysaccharide inner core triggers membrane permeabilization/depolarization, lipid peroxidation and hypervesiculation. In turn, it favors the regulation of TiO2NP-mediated changes in cell Turgor stress and leads to efficient vesicle-facilitated release of damaged membrane components. Remarkably, vesicles further act as electrostatic baits for TiO2NPs, thereby mitigating TiO2NPs toxicity. Altogether, we highlight antagonistic lipopolysaccharide-dependent bacterial responses to nanoparticles and we show that the destabilized membrane can generate unexpected resistance phenotype.

Cadmium transport activity of four mercury transporters (MerC, MerE, MerF and MerT) and effects of the periplasmic mercury-binding protein MerP on Mer-dependent cadmium uptake

ABSTRACT Mercury superfamily proteins, i.e. inner membrane-spanning proteins (MerC, MerE, MerF and MerT) and a periplasmic mercury-binding protein (MerP), transport mercury into the cytoplasm. A previous study demonstrated that a Mer transporter homolog exhibits cadmium transport activity; based on this, the present study aimed to evaluate the cadmium transport activity of MerC, MerE, MerF and MerT and the effects of MerP co-expression in Escherichia coli. Bacteria expressing MerC, MerE, MerF or MerT without MerP were more sensitive to cadmium and significantly absorbed more cadmium than did the control strain. Expression of MerP in combination with MerC, MerE, MerF or MerT increased the bacterial sensitivity to cadmium and cadmium accumulation compared to a single expression of MerC, MerE, MerF or MerT. Cadmium uptake mediated by MerC, MerE, MerF or MerT was inhibited under cold or acidic conditions. These findings suggest that MerC, MerE, MerF and MerT are broad-spectrum heavy metal transporters that mediate both mercury and cadmium transport into cells and that MerP accelerates the cadmium transport ability of MerC, MerE, MerF and MerT.