Medical Face Masks Do Not Affect Acid-Base Balance Yet Might Facilitate the Transmission of Staphylococcus aureus in Hospital Settings during the COVID-19 Pandemic.

INTRODUCTION: Due to the SARS-CoV-2 coronavirus pandemic, the wearing of masks has become a common phenomenon. Most of the undesirable effects of using a protective face covering are usually related to the prolonged time of its wearing, and the adverse consequences of face coverings should be considered two-fold. The aim of the study was to evaluate the rate of contamination of the three types of face coverings (surgical, N95, and FFP2 masks) with the microorganism-aerobic bacteria, yeasts, and molds-after the 3 h exposure time. The study aimed to investigate the effects of wearing FFP2 masks (KN95) on respiratory function and the acid-base balance of the human body. RESULTS: The presence of S. aureus was confirmed in both nasal carriers and non-carriers which may demonstrate the cross-contamination and spread of this bacterium via hands. S. aureus was found on external and internal surfaces of face masks of each type, and therefore could also be transmitted via hands from external sources. The 3 h exposure time is not sufficient for Gram-negative rods and mold contamination. Moreover, there were no significant differences in most of the parameters studied between the first and second examinations, both in spirometry and capillary blood gas analysis (p > 0.05).

Analysis of the prevalence of colistin resistance among clinical strains of Klebsiella pneumoniae.

INTRODUCTION AND OBJECTIVE: Klebsiella pneumoniae is an essential component of the human gut microflora. However, it can pose a threat by causing opportunistic infections, especially in hospitalised or immunocompromised patients. It is a serious problem for health medicine, primarily because of increasing resistance to previously used antibiotics. Infections with multidrug-resistant strains are difficult to treat, creating a challenge for clinicians. Also of growing concern is the increasing resistance to the drug of last resort - colistin (CL). The aim of the study is to determine the prevalence of resistance to CL among clinical K. pneumoniae strains. MATERIAL AND METHODS: The study was conducted on 200 clinical strains of K. pneumoniae. Drug susceptibility, production of resistance mechanisms, and determination of the minimum inhibitory concentration of CL were evaluated. RESULTS: Of all isolates, 73.0% produced carbapenemases, while the remainder produced an extended substrate spectrum - ß-lactamases (ESBLs). All strains showed a diverse antibiotic resistance profile. Resistance to CL was noted among 14.5% of carbapenemase-producing strains, particularly MBL and OXA-48. ESBL-positive strains showed full susceptibility to CL. CONCLUSIONS: Although a low rate of CL resistance was observed, this was true for strains simultaneously producing carbapenemases. Such strains should be under special epidemiological surveillance due to their potential to cause epidemic outbreaks. Monitoring the prevalence of clinical CL-resistant strains would allow for more effective counteraction against pathogens in various fields, including medicine, agriculture, veterinary medicine and industry.

Determination of nasal carriage and skin colonization, antimicrobial susceptibility and genetic relatedness of Staphylococcus aureus isolated from patients with atopic dermatitis in Szczecin, Poland.

BACKGROUND: Atopic dermatitis (AD) is one of the most frequent chronic and inflammatory skin condition. AD is characterized by damaged epidermal barrier, xerosis and pruritus of eczematous skin lesions which tend to flare. The duration and frequency of exacerbation of AD symptoms markedly affects the quality of patient life. AD results from the interplay between host genetics, immunity, and environmental factors, however the detailed pathogenesis of this disease is still not entirely cleared. Furthermore, disturbances of the skin microbiota and skin functional impairment predispose to secondary skin infections. Staphylococcus aureus colonizes skin and mucous membranes of 20 to 80% of healthy individuals and of 90% of patients with AD in whom this bacterium is accounted as an important AD exacerbating factor. It is also proven, that S. aureus nasal carriage significantly increases the risk for self-transmission and endogenous infection. In the current study the presence of S. aureus either in nasal vestibule and on lesioned skin of 64 patients with AD enrolled in 10-year autovaccination program was determined. The genetic relatedness of 86 S. aureus isolated from patients nose and skin using Pulsed Field Gel Electrophoresis (PFGE) and antimicrobial susceptibility of all strains to methicillin, erythromycin, clindamycin, mupirocin, gentamicin, amikacin, tetracycline, chloramphenicol and cotrimoxazole was also evaluated. RESULTS: In total 23 PFGE genotypes and 24 unique patterns were distinguished. 34 patients were S. aureus nasal carriers. Simultaneous presence of S. aureus in nose and on affected skin was found in 16 carriers colonized by indistinguishable or potentially related S. aureus vs 2 carriers colonized with non-related S. aureus in nasal vestibule and on skin. 4 isolates were methicillin resistant (MRSA) among which 3 showed constitutive MLSB resistance phenotype and remaining one was resistant to tetracycline and chloramphenicol. In 4 isolates inducible MLSB resistance phenotype was found, one of them was additionally resistant to tetracycline. 7 S. aureus were mupirocin resistant among them 3 - isolated from one patient, were resistant simultaneously to tetracyclines and chloramphenicol. 7 strains demonstrated resistance to chloramphenicol and susceptibility to all tested antimicrobial agents. The susceptibility to gentamicin, amikacin and cotrimoxazole among all examined S. aureus was confirmed. CONCLUSION: The obtained results indicated non-clonal structure of S. aureus circulating in AD patients. PFGE results showed the clonal-structure of vast majority of S. aureus isolated from nose and skin from nasal carriers what may prove the autoinfection in these patients. All examined patients the moderate or strong severity of AD was reported. Susceptibility to most antibiotics among isolated strains was also observed.

Environmental Phage-Based Cocktail and Antibiotic Combination Effects on Acinetobacter baumannii Biofilm in a Human Urine Model.

The emergence of multidrug-resistant (MDR) bacterial infections poses a catastrophic threat to medicine. The development of phage-based therapy combined with antibiotics might be an advantageous weapon in the arms race between human and MDR bacteria. A cocktail composed of the MDR Acinetobacter baumannii infecting bacteriophages with high lytic activity was used in combination with antibiotics to destroy a bacterial biofilm in human urine. A. baumannii exhibited varying susceptibility to the host range of bacteriophages used in this study, ranging from 56% to 84%. This study demonstrated that bacteriophages could reduce biofilm biomass in a human urine model, and some of the antibiotics commonly used in the treatment of urinary tract infection (UTI) act synergistically with phage cocktails. Additionally, the combined treatment showed a significantly greater reduction of biofilm biomass and clearance of persister cells.

Genotypic characterisation and antimicrobial resistance of Pseudomonas aeruginosa strains isolated from patients of different hospitals and medical centres in Poland.

BACKGROUND: Pseudomonas aeruginosa is a Gram-negative bacteria responsible for infections in immunocompromised patients and is one of the most common causes of nosocomial infections particularly in intensive care and burn units. We aimed to investigate the population structure of P. aeruginosa strains isolated from patients at different hospital wards. METHODS: We analysed the possible presence of P. aeruginosa epidemic or endemic strains in hospitals of the selected region. A genotyping analysis was performed for P. aeruginosa isolates (n = 202) collected from patients of eleven hospitals in north-western Poland. Collections of P. aeruginosa were genotyped using pulsed-field gel electrophoresis (PFGE). Phenotypic screening for antibiotic susceptibility was performed for the common antimicrobial agents. RESULTS: Pseudomonas aeruginosa isolates were distributed among 116 different pulsotype groups. We identified 30 groups of clonally related strains, each containing from 2 to 17 isolates and typed the obtained 13 unique patterns, designated as A, D, E, J, K, M, N, Ó, P, T, X, AC, AD, and AH. The two largest clusters, D and E, contained 17 and 13 isolates, respectively. Strains of these groups were continuously isolated from patients at intensive care units and burn units, indicating transmission of these strains. CONCLUSIONS: In this study, we demonstrate the clonal relatedness of P. aeruginosa strains and their constant exchange in hospitals over a period of 15 months. The obtained results indicate a predominantly non-clonal structure of P. aeruginosa.

Ultrasound irradiation effect on morphological and adsorptive properties of a nanoscale 3D Zn-coordination polymer and derived oxide.

In this work, Zn-based coordination polymer [Zn2(1,3-bdc)bzim2]n was successfully synthesized by the sonochemical method using a 13 mm probe-type ultrasound operating at 20 kHz and amplitudes of 30, 40 and 50% corresponding to an acoustic power of 5.5, 8.6, and 10.3 W, respectively. Additionally, a sample was prepared by the slow-diffusion method for comparison. The samples were characterized by FTIR, PXRD, SEM, and BET techniques. The influence of the time and sonication amplitude on the yield of the reaction, crystallite size, and morphology were also studied. It was found that the sonochemical method provided the desired product in 83.9% within 20 min of sonication using the highest level of sonication amplitude. Moreover, this approach resulted in regular, controlled morphology, smaller particles, and higher surface area of the Zn-sample and derived oxide, than the slow diffusion method. The samples prepared by different methodologies were tested for the adsorption of BTEX (benzene, toluene, ethylbenzene, and xylenes) components in six different systems, and the uptakes were quantified by 13C NMR spectroscopy. Both samples showed excellent adsorption of benzene, 119.8 mmol/g, and 88.1 mmol/g, for the coordination polymers prepared via the sonochemical and slow-diffusion methods, respectively, corresponding to 63.9%, and 46.9%. These results are in agreement with the non-polar surface of these samples.

Antibiotics Act with vB_AbaP_AGC01 Phage against Acinetobacter baumannii in Human Heat-Inactivated Plasma Blood and Galleria mellonella Models.

Increasing multidrug resistance has led to renewed interest in phage-based therapy. A combination of the bacteriophages and antibiotics presents a promising approach enhancing the phage therapy effectiveness. First, phage candidates for therapy should be deeply characterized. Here we characterize the bacteriophage vB_AbaP_AGC01 that poses antibacterial activity against clinical Acinetobacter baumannii strains. Moreover, besides genomic and phenotypic analysis our study aims to analyze phage-antibiotic combination effectiveness with the use of ex vivo and in vivo models. The phage AGC01 efficiently adsorbs to A. baumannii cells and possesses a bacteriolytic lifecycle resulting in high production of progeny phages (317 ± 20 PFU × cell-1). The broad host range (50.27%, 93 out of 185 strains) against A. baumannii isolates and the inability of AGC01 to infect other bacterial species show its high specificity. Genomic analysis revealed a high similarity of the AGC01 genome sequence with that of the Friunavirus genus from a subfamily of Autographivirinae. The AGC01 is able to significantly reduce the A. baumannii cell count in a human heat-inactivated plasma blood model (HIP-B), both alone and in combination with antibiotics (gentamicin (GEN), ciprofloxacin (CIP), and meropenem (MER)). The synergistic action was observed when a combination of phage treatment with CIP or MER was used. The antimicrobial activity of AGC01 and phage-antibiotic combinations was confirmed using an in vivo larva model. This study shows the greatest increase in survival of G. mellonella larvae when the combination of phage (MOI = 1) and MER was used, which increased larval survival from 35% to 77%. Hence, AGC01 represents a novel candidate for phage therapy. Additionally, our study suggests that phages and antibiotics can act synergistically for greater antimicrobial effect when used as combination therapy.

Enterobacteriaceae infections of very low birth weight infants in Polish neonatal intensive care units: resistance and cross-transmission.

BACKGROUND: The aims of our study were analysis of the occurrence of infections by members of the Enterobacteriaceae family in 6 Polish neonatal intensive care units in 2009, their drug resistance, the epidemiology of extended-spectrum ß-lactamase (ESBL)-producing strains and the possibility of using modern tools of microbiology diagnosis in infection control, especially for the reduction of antimicrobial resistance. METHODS: A prospective surveillance covered 910 newborns. Case patients were defined as neonates with very low birth weight who had clinical signs of septicemia, pneumonia or necrotizing enterocolitis. Early-onset infection was defined as infection diagnosed within 3 days after delivery. RESULTS: The incidence of Enterobacteriaceae infections was 2.6/1000 patient-days. The risk of Enterobacteriaceae pneumonia increased with the length of hospitalization (P = 0.0356). The most common pathogen was Escherichia coli (12.4% of all strains, in early-onset infection 18.5%) and Klebsiella spp. (9.1% of all). The ESBL phenotype was found in 37% of isolates, of which 89.3% were producing CTX-M-type, 70.2% TEM-type and 8.5% SHV-type. Epidemic clones were detected in the 2 studied neonatal intensive care units: 6 of the 9 ESBL-positive Enterobacter cloacae and 16 of the 18 ESBL-positive Klebsiella pneumoniae strains were classified into 1 epidemic clone, which showed resistance to penicillin without inhibitors, amoxycillin/clavulanic acid, cephalosporins, aztreoname, aminoglycosides and trimethoprim/sulfamethoxazole. CONCLUSIONS: Enterobacteriaceae bacilli are a significant problem in neonatal intensive care units, especially in early-onset infection and for long hospitalized very low birth weight infants. The observed high drug resistance was in large part related to the dominance of epidemic strains as a result of horizontal transmission. The best way to reduce drug resistance would be adequate procedures of isolation and hand hygiene.

Does prenatal antibiotic therapy compromise the diagnosis of early-onset infection and management of the neonate?

AIM: To assess the impact of prenatal antibiotic treatment on procalcitonin (PCT) and C-reactive protein (CRP) concentrations in cord blood, and on the rate of positive neonatal blood cultures. METHODS: Neonates with early-onset infection (Group A; n=46) were compared with healthy controls (Group B; n=240). We evaluated the relationship between prenatal antibiotic therapy and early-onset infection, and for interactions with antibiotic therapy in the neonate immediately after birth. RESULTS: In the Group A antibiotics were administered significantly more often prenatally and more often to neonates just after birth. The percentage of negative blood cultures in infected neonates was higher when antibiotic treatment was instituted prenatally. Differences in cord blood PCT and CRP concentrations were significant between both groups and were independent of prenatal antibiotic treatment. Streptococcus agalactiae was the most frequent species. CONCLUSIONS: Almost one-third of neonates present with early-onset infection in spite of prenatal antibiotic therapy. Cord blood PCT and CRP measurements may be helpful in the diagnosis of infection also in cases when antibiotic therapy was started prenatally. Prenatal antibiotic administration reduced the number of positive blood cultures in neonates with early-onset infection and was associated with a greater rate of antibiotic treatment after birth in neonates without infection.

Association of recurrent furunculosis with Panton-Valentine leukocidin and the genetic background of Staphylococcus aureus.

Staphylococcus aureus is a major cause of skin and soft tissue infections, such as furuncles, carbuncles, and abscesses, but it also frequently colonizes the human skin and mucosa without causing clinical symptoms. Panton-Valentine leukocidin (PVL) is a pore-forming toxin that has been associated with soft tissue infections and necrotizing pneumonia. We have compared the genotypes, virulence gene repertoires, and phage patterns of 74 furunculosis isolates with those of 108 control strains from healthy nasal carriers. The large majority of furunculosis strains were methicillin sensitive. Clonal cluster (CC) 121 (CC121) and CC22 accounted for 70% of the furunculosis strains but for only 8% of the nasal isolates. The PVL-encoding genes luk-PV were detected in 85% of furunculosis strains, while their prevalence among colonizing S. aureus strains was below 1%. luk-PV genes were distributed over several lineages (CCs 5, 8, 22, 30, and 121 and sequence type 59). Even within the same lineages, luk-PV-positive phages characterized furunculosis strains, while their luk-PV-negative variants were frequent among nasal strains. The very tight epidemiological linkage between luk-PV and furunculosis, which could be separated from the genetic background of the S. aureus strain as well as from the gene makeup of the luk-PV-transducing phage, lends support to the notion of an important role for PVL in human furunculosis. These results make a case for the determination of luk-PV in recurrent soft tissue infections with methicillin-sensitive as well as methicillin-resistant S. aureus.

Molecular studies of an impetigo bullosa epidemic in full-term infants.

BACKGROUND: Carriers of Staphylococcus aureus strains can be the source of epidemic infection for patients. OBJECTIVES: A molecular epidemiological analysis of an impetigo bullosa outbreak in a neonatal ward was performed in order to determine a potential source of the infection and possible routes of subsequent spreading of the epidemic strain. METHODS: The genetic relatedness of S. aureus strains isolated from 6 neonates with epidermal lesions and from 21 staff members was verified by the pulsed field gel electrophoresis (PFGE) method. Additionally, detection of eta and etb genes of S. aureus strains using PCR was performed. RESULTS: None of the infected newborns' mothers was a carrier. Seven strains, 6 isolated from the newborns and 1 taken from a midwife, showed the same restriction pattern, i.e. type A. In the other 20 health care workers colonized with S. aureus, 3 genetic types could be distinguished, i.e. B (2), C (7) and D (2), as well as 9 strains with unique PFGE patterns. The eta gene detected in 7 strains belonged to the genetic type A; there was no etb gene in any of the 27 S. aureus isolates. CONCLUSIONS: The presence of the same genetic type A of S. aureus in the infected newborns is a factor which indicates that the impetigo bullosa was a hospital infection. A probable source of the infection was a midwife who was colonized with the same S. aureus type. She was present at the birth of the first infected newborn. Today, molecular methods are essential for prompt recognition of an epidemic and implementation of appropriate infection control strategies.

NK cell depletion and recovery in SCID mice treated with anti-NK1.1 antibody.

The anti-NK1.1 antibody produced by PK136 hybridoma cell line administered subcutaneously to SCID mice effectively decreased the level of peripheral blood NK cells and weight of the spleen for 3-4 days. The antibody treatment did not harm the general state of the animal, and may be practically applied in xenograft experiments.