Main Metabolites of Pseudomonas aeruginosa: A Study of Electrochemical Properties.

Pseudomonas aeruginosa is a ubiquitously distributed soil and water bacterium and is considered an opportunistic pathogen in hospitals. In cystic fibrosis patients, for example, infections with P. aeruginosa can be severe and often lead to chronic or even fatal pneumonia. Therefore, rapid detection and further identification are of major importance in hospital hygiene and infection control. This work shows the electrochemical properties of five P. aeruginosa key metabolites considering their potential use as specific signaling agents in an electrochemical sensor system. The pure solutes of pyocyanin (PYO), Pseudomonas quinolone signal (PQS), pyochelin (PCH), 2-heptyl-4-hydroxyquinoline (HHQ), and 2-heptyl-4-hydroxyquinoline N-oxide (HQNO) were analyzed by different electrochemical techniques (cyclic and square wave voltammetry) and measured using a Gamry Reference 600+ potentiostat. Screen-printed electrodes (DropSens DRP110; carbon working and counter, silver reference electrode) were used to determine signal specificities, detection limits, as well as pH dependencies of the substances. All of the compounds were electrochemically inducible with well-separated oxidation and/or reduction peaks at specific peak potentials relative to the reference electrode. Additionally, all analytes exhibited linear concentration dependency in ranges classically reported in the literature. The demonstration of these properties is a promising step toward direct multiplexed detection of P. aeruginosa in environmental and clinical samples and thus, can make a significant contribution to public health and safety.

Gram-Positive Bacteria Increase Breast Implant-Related Complications: Prospective Analysis of 100 Revised Implants.

BACKGROUND: Breast implant-related complications can be reduced by strict antiseptic precautions during insertion, but bacteria can often be found on implant surfaces on the occasion of revision surgery. The authors prospectively analyzed the association of bacteria found on breast implant surfaces with implant-related complications in breast implant revision cases. METHODS: The authors analyzed a total of 100 breast implant revisions in 66 patients between August of 2018 and January of 2021. Capsular swabs and capsular samples were taken intraoperatively. Analyses on the occurrence of bacteria and the occurrence of implant-related complications were performed. In addition, correlations between bacteria-contaminated breast implant surfaces and implant-related complications were performed. RESULTS: Implant-related complications (perforation, rupture, capsular contraction) were observed in 42 implant sites: eight unilateral and 34 bilateral cases. In total, 16 swabs showed positive bacterial growth, 10 of which were associated with a breast implant-related complication (χ 2 = x, y, and z; P = 0.006). The most common implant-based complication at contaminated prosthetics was implant rupture. The association of contaminated breast implants and implant rupture was statistically significant. CONCLUSIONS: The authors identified a correlation between implant complications and Gram-positive bacteria found on breast implant surfaces. The most common implant-based complication seen at simultaneously positive samples was implant rupture in 50% of the authors' cases. No capsular contraction or other complications were seen. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

The bacterial pathogen and resistance spectrum in a dermatological inpatient ward: a six-year, retrospective, epidemiological study.

Aim: Treatment of bacterial soft tissue infections is an essential part of clinical dermatology, and the choice of antibiotic therapy is often empirical. The aim of this longitudinal retrospective study was to evaluate bacterial epidemiology, resistance patterns and antibiotic consumption in a dermatological inpatient ward. Method: Bacterial isolates and antimicrobial susceptibility testing from a dermatological inpatient ward were recorded retrospectively from 2011 to 2016. The antibiotic consumption was evaluated and given as the assumed defined daily dose [DDD] per 100 days of covering per year. Results: A total of 4,800 bacterial isolates were included (skin, mucous membrane and wounds 87%, urine 9.5%, blood 1.7%, tissue and tissue fluids 1.6%). The proportion of Gram-positive bacteria was 58% (Staphy loc occus aureus 37.8%, coagulase-negative staphylococci 21.5%, Enterococcus spp. 16.7%). Pseudomonas aeruginosa (27.2%), Escherichia coli (17.5%) and Proteus spp. (13.1%) were the most common Gram-negative bacteria. The proportion of multi-resistant pathogens was 5.8% for methicillin-resistant S. aureus, 0.9%, 0.8% and 1.8% for multi-resis tant P. aeruginosa, ESBL-producing E. coli and ESBL-producing Klebsiella pneumoniae of all isolates. Beta-lactam antibiotics were the most used drugs (14.4, 10.8, and 9.6 DDD/100 for aminopenicillins, cefalexin, and penicillin G), followed by clindamycin (9.0 DDD/100 patient days). Conclusion: In view of the frequency of bacterial soft tissue infections and their need for inpatient treatment with mostly empirically chosen antibiotics, systematic microbiological surveillance should be recommended for dermatological inpatient wards.

Human Pathogenic Candida Species Respond Distinctively to Lactic Acid Stress.

Several Candida species are opportunistic human fungal pathogens and thrive in various environmental niches in and on the human body. In this study we focus on the conditions of the vaginal tract, which is acidic, hypoxic, glucose-deprived, and contains lactic acid. We quantitatively analyze the lactic acid tolerance in glucose-rich and glucose-deprived environment of five Candida species: Candidaalbicans, Candida glabrata, Candida parapsilosis, Candida krusei and Candida tropicalis. To characterize the phenotypic space, we analyzed 40-100 clinical isolates of each species. Each Candida species had a very distinct response pattern to lactic acid stress and characteristic phenotypic variability. C. glabrata and C. parapsilosis were best to withstand high concentrations of lactic acid with glucose as carbon source. A glucose-deprived environment induced lactic acid stress tolerance in all species. With lactate as carbon source the growth rate of C. krusei is even higher compared to glucose, whereas the other species grow slower. C. krusei may use lactic acid as carbon source in the vaginal tract. Stress resistance variability was highest among C. parapsilosis strains. In conclusion, each Candida spp. is adapted differently to cope with lactic acid stress and resistant to physiological concentrations.

The role of Lactobacillus species in the control of Candida via biotrophic interactions.

Microbial communities have an important role in health and disease. Candida spp. are ubiquitous commensals and sometimes opportunistic fungal pathogens of humans, colonizing mucosal surfaces of the genital, urinary, respiratory and gastrointestinal tracts and the oral cavity. They mainly cause local mucosal infections in immune competent individuals. However, in the case of an ineffective immune defense, Candida infections may become a serious threat. Lactobacillus spp. are part of the human microbiome and are natural competitors of Candida in the vaginal environment. Lactic acid, low pH and other secreted metabolites are environmental signals sensed by fungal species present in the microbiome. This review briefly discusses the ternary interaction between host, Lactobacillus species and Candida with regard to fungal infections and the potential antifungal and fungistatic effect of Lactobacillus species. Our understanding of these interactions is incomplete due to the variability of the involved species and isolates and the complexity of the human host.

Characterization of Bacteria and Inducible Phages in an Intensive Care Unit.

Intensive care units (ICUs) are critical locations for the transmission of pathogenic and opportunistic microorganisms. Bacteria may develop a synergistic relationship with bacteriophages and more effectively resist various stresses, enabling them to persist despite disinfection and antimicrobial treatment. We collected 77 environmental samples from the surroundings of 12 patients with infection/colonizations by Escherichia coli, Staphylococcus aureus or Klebsiella spp in an ICU in Austria. Surface swabs were tested for lytic phages and bacterial isolates for mitomycin C-inducible prophages. No lytic bacteriophages were detected, but S. aureus was isolated from the surroundings of all patients. About 85% of the colonies isolated from surface samples were resistant to antimicrobials, with 94% of them multidrug resistant. Two inducible temperate bacteriophages-myovirus vB_EcoM_P5 and siphovirus vB_SauS_P9-were recovered from two clinical isolates. Staphylococci phage vB_SauS_P9 lysed S. aureus isolates from the surface swabs collected from the surroundings of three patients. No transductants were obtained on propagation in phage-sensitive antimicrobial-resistant isolates. The two phages were sensitive to 0.25% (v/v) of the disinfectant TPH Protect, which eliminated viable phages after 15 min. Coliphage vB_EcoM_P5 was inactivated at 70 °C and staphylococci phage vB_SauS_P9 at 60 °C after 60 min.

Natural Occurrence of Escherichia coli-Infecting Bacteriophages in Clinical Samples.

The interaction between bacteriophages, bacteria and the human host as a tripartite system has recently captured attention. The taxonomic diversity of bacteriophages, as a natural parasite of bacteria, still remains obscure in human body biomes, representing a so-called "viral dark matter." Here, we isolated and characterized coliphages from blood, urine and tracheal aspirates samples collected at a tertiary care hospital in Austria. Phages were more often isolated from blood, followed by urine and tracheal aspirates. Phylogenetic analysis and genome comparisons allowed the identification of phages belonging to the Tunavirinae subfamily, and to the Peduovirus and Tequintavirus genera. Tunavirinae phages cluster together and are found in samples from 14 patients, suggesting their prevalence across a variety of human samples. When compared with other phage genomes, the highest similarity level was at 87.69% average nucleotide identity (ANI), which suggests that these are in fact a newly isolated phage species. Tequintavirus phages share a 95.90% with phage 3_29, challenging the ANI threshold currently accepted to differentiate phage species. The isolated phages appear to be virulent, with the exception of the Peduovirus members, which are integrative and seem to reside as prophages in bacterial genomes.

Sensor-operated faucets: a possible source of nosocomial infection?

Recently, contamination of sensor-operated faucets (SOFs) with Pseudomonas aeruginosa was observed. To evaluate odds ratios, we conducted a case-control study in which handle-operated faucets served as controls. No statistically significant difference in P. aeruginosa counts was observed between SOFs and regular faucets in our study (odds ratio, 0.0; 95% confidence interval, 0.0 to 39.0; two-sided P exact = .99).

Nosocomial outbreak of Serratia marcescens in a neonatal intensive care unit.

OBJECTIVES: To investigate and describe an outbreak of Serratia marcescens in a neonatal intensive care unit (NICU) and to report the interventions leading to cessation of the outbreak. SETTING: A 2,168-bed, tertiary-care, university teaching hospital in Vienna, Austria, with an 8-bed NICU. DESIGN: We conducted a case-control study to identify risk factors for colonization and infection with S. marcescens. A case-patient was defined as any neonate in the NICU with a positive culture for S. marcescens between October 1, 2000, and February 28, 2001. Polymerase chain reaction was applied to type isolates. METHODS: During unannounced observations, the NICU was examined and existing policies were reviewed. Staff were reinstructed in hand antisepsis and gloving policies. Admissions were halted on December 27. During previously planned technical maintenance of the ward, the NICU was closed for 10 days and thorough aldehyde-based disinfection of the NICU was performed. RESULTS: Ten neonates met the case definition: 6 with infections (among them 3 with cerebral abscesses) and 4 with asymptomatic colonization. Previous antibiotic treatment of the mothers with cefuroxime was the single significant risk factor for colonization or infection (P = .028; odds ratio, 17; 95% confidence interval, 1.3 to 489.5). CONCLUSIONS: S. marcescens can cause rapidly spreading outbreaks associated with fatal infections in NICUs. With aggressive infection control measures, such outbreaks can be stopped at an early stage. Affected neonates themselves may well be the source of cross-infection to other patients on the ward. Antibiotic treatment of mothers should be reevaluated to avoid unnecessary exposure to antibiotics with the potential of over-growth of resistant organisms.

Prophylaxis of ophthalmia neonatorum--a nationwide survey of the current practice in Austria.

UNLABELLED: The aim of this study was to analyze the current practice of Ophthalmia neonatorum prophylaxis in Austria. Questionnaires were sent to 107 hospitals with obstetric units, as well as to 490 registered community midwives, together looking after a yearly total of approximately 70,000 births. The overall return of the hospitals and midwives was 91.6% and 7.6%, respectively. RESULTS: Ophthalmia neonatorum prophylaxis is being applied by 93.8% of all respondents (hospitals 96.9%, and community midwives 82.3%). The three most frequently applied substances were Erythromycin (41.8%), Gentamicin (21.3%) and Silver nitrate (19.7%). Other substances were Tetracycline, Povidone-Iodine, Neomycin and Chloramphenicol. The reported overall-observation of chemical conjunctivitis after application of a prophylactic agent was 42.3% (55/133), typically after the use of Silver nitrate, Erythromycin or Tetracycline. The agent was determined by pediatricians (29%), in accordance to governmental decree (15%), by hospital policy (12%), effectiveness against Chlamydia and Gonococci (9%), by pharmacists (3%) and ophthalmologists (3%). 18% did not give any reason for the choice of agent. CONCLUSION: The rationale for prophylaxis and the substances used in Austria show heterogeneity. Seven prophylactic agents are used, two antiseptics and five antibiotics. 25% of the routine applicants are using substances (Gentamicin, Neomycin or Chloramphenicol) for which no evidence based efficacy for prophylaxis of Ophthalmia neonatorum has been demonstrated through clinical trials. However, 83.5% of the maternity units do not want changes in their current routine, unless there is a nation-wide agreement for Ophthalmia neonatorum prophylaxis.