Staphylococcal Strains Research Articles

Epidemiology of purulent-septic infections caused by methicillin-resistant Staphylococcus in the Republic of Moldova

Staphylococcus infections are a major global concern, caused by the annual growth of methicillin-resistant Staphylococcus strains and the emergence of strains resistant to reserve anti-staphylococcal antibiotics. Aim: The aim of the study was to determine the risk factors, the degree of spread of methicillin-resistant Staphylococcus (MRS) strains in health care facilities in the Republic of Moldova, as well as their resistance to antibacterial drugs. Material and methods: The research of the real incidence, epidemiological peculiarities and the degree of sensitivity/resistance of MRS infections to antibiotics was performed based on the descriptive cross-sectional observational epidemiological study, overall being analyzed 10,055 staphylococcal strains. The risk factors and socio-economic impact were determined based on a retrospective case-control study. The research group included 269 patients with bacteriological investigations positive for methicillin-resistant Staphylococcus (MRS), the control group - 159 patients with bacteriological investigations positive for methicillin-sensitive Staphylococcus (MSS). Results: The share of MRS strains among Staphylococcus strains in the Republic of Moldova is on average 35.97%. A higher level of spread of MRS strains is recorded in maternity hospitals - 61.81%, followed by multi-profile health care facilities - 36.32%, slightly lower in rural health care facilities - 22.36%. The prevalence of MRS strains varied depending on the profile of departments and pathological products. Most often, MRS strains were isolated from patients in the departments of surgery, traumatology, orthopedics, resuscitation and intensive care. A high level of MRS was found in blood cultures - 76.11%, and 96.3% of MRS strains isolated from blood proved to be polyresistant.

Antimicrobial Resistance Profiles and Genes of Staphylococci Isolated from Mastitic Cow's Milk in Kenya.

Increasing numbers of potentially zoonotic multidrug-resistant (MDR) staphylococci strains, associated with mastitis in dairy cows, are being reported globally and threaten disease management in both animal and human health. However, the prevalence and antimicrobial resistance profiles of these strains, including methicillin-resistant staphylococci (MRS), in Kenya is not well known. This study investigated the drug resistance profiles and genes carried by 183 staphylococci isolates from 142 dairy cows representing 93 farms recovered from mastitis milk of dairy cows in two selected counties in Kenya. Staphylococci isolates were characterized by phenotypic characteristics, polymerase chain reaction (PCR) amplification, partial sequencing and susceptibility testing for 10 antimicrobial drugs. Detection of seven resistance genes to the various antimicrobial drugs was conducted using PCR. Overall, phenotypic resistance among the staphylococci ranged between 66.1% for ampicillin and 3.5% for fluoroquinolones. Twenty-five percent (25%) of S. aureus and 10.8% of the coagulase-negative staphylococci (CoNS) isolates, were methicillin-resistant staphylococci phenotypically (defined as resistance to cefoxitin disk diffusion). The most common genes found in S. aureus and CoNS were blaZ and strB at 44.3% and 26%, and 78% and 50%, respectively. MDR was observed in 29.67% and 16.3% of S. aureus and CoNS, respectively. These findings pose a threat to bovine mastitis treatment and management as well as human health.

Pharmacokinetic/Pharmacodynamic Analysis of Tedizolid Phosphate Compared to Linezolid for the Treatment of Infections Caused by Gram-Positive Bacteria.

Tedizolid and linezolid have antibacterial activity against the most important acute bacterial skin and skin-structure infection (ABSSSIs) pathogens. The objective of this work was to apply PK/PD analysis to evaluate the probability of attaining the pharmacodynamic target of these antimicrobials based on the susceptibility patterns of different clinical isolates causing ABSSSI. Pharmacokinetic and microbiological data were obtained from the literature. PK/PD breakpoints, the probability of target attainment (PTA) and the cumulative fraction of response (CFR) were calculated by Monte Carlo simulation. PTA and CFR are indicative of treatment success. PK/PD breakpoints of tedizolid and linezolid were 0.5 and 1 mg/L, respectively. Probability of treatment success of tedizolid was very high (>90%) for most staphylococci strains, including MRSA and coagulase-negative staphylococci (CoNS). Only for methicillin- and linezolid-resistant S. aureus (MLRSA) and linezolid resistant (LR) CoNS strains was the CFR of tedizolid very low. Except for LR, daptomycin-non-susceptible (DNS), and vancomycin-resistant (VRE) E. faecium isolates, tedizolid also provided a high probability of treatment success for enterococci. The probability of treatment success of both antimicrobials for streptococci was always higher than 90%. In conclusion, for empiric treatment, PK/PD analysis has shown that tedizolid would be adequate for most staphylococci, enterococci, and streptococci, even those LR whose linezolid resistance is mediated by the cfr gene.

English

BACKGROUND Orthopaedic implant site infection is one of the major problems of surgical site infection associated with high morbidity and mortality. As implants are commonly used in orthopaedic procedures and especially when preceded by trauma, orthopaedic procedures are more prone for surgical site infections. We wanted to study the aerobic bacterial aetiology of infected orthopaedic implants. METHODS This was a cross sectional study carried out over a period of one and half years. The study group comprised of 100 patients who had undergone orthopaedic prosthetic implant surgeries and presented with signs and symptoms of infections. The demographic data were recorded, type of surgery, the time of infection during postoperative period and risk factors were noted. Serous / purulent discharge adjacent to infected implants were processed in the laboratory as per the standard protocol. RESULTS Among the 100 samples studied, 79 % were culture positive and 21 % culture sterile. 55.7 % were Gram-positive cocci isolated in pure, 29.1 % were Gramnegative bacilli (GNB) isolated in pure and 15.2 % were a mixture of Gram-positive cocci and Gram-negative bacilli. Staphylococcus aureus 45 (80.4 %) was the predominant isolate followed by Coagulase Negative staphylococci 11(19.6 %). Among the GNB (35), the predominant isolate was Pseudomonas aeruginosa 10 (28.6 %) followed by Klebsiella pneumoniae 8 (22.9 %). Infections occurred during the early post-operative period in 63 % cases. Methicillin resistant Staphylococcus aureus were 53.4 % and 35 % were extended spectrum beta lactamases (ESBL) among Enterobacteriaceae strains. CONCLUSIONS Orthopaedic implant site infections are common during early post-operative period. Methicillin resistant staphylococcus and ESBL strains were high. This study of aerobic bacterial analysis and their current antibiogram of orthopaedic implant infections would greatly help the orthopaedic surgeons in selecting appropriate antibiotics for prophylaxis as well as better management of patients. KEYWORDS Orthopaedic Implants, MRSA, ESBL, Orthopaedic Implant Infections, Biofilm

Infections du tractus urinaire en milieu pédiatrique : écologie bactérienne et sensibilité aux antibiotiques au Centre hospitalier universitaire pédiatrique Charles-de-Gaulle de Ouagadougou (Burkina Faso)

IntroductionUrinary tract infection is the second most common bacterial infection in children, after respiratory tract infection. The objective of this work was to study the bacterial ecology and antibiotic susceptibility of germs isolated during childhood urinary tract infections at the Paediatric University Hospital Charles-de-Gaulle in Ouagadougou. Patients and methodThis was a descriptive retrospective study covering the period from July 1st, 2010 to June 30, 2015, including 141 children from 0 to 15 years old hospitalized in the medical paediatrics department for a urinary tract infection. ResultsThe hospital frequency of urinary tract infection was 0.7%. The mean age of the patients was 43.1 months. Female patients accounted for 57.4%, a sex-ratio of 0.7. Gram-negative bacilli were often involved (67.4%) with Escherichia Coli and Klebsiella in 35.5% and 22% of cases respectively. The main Gram-positive bacteria were staphylococci (15.5%), enterococci (11.3%) and streptococci (5.6%).Enterobacteriaceae isolated were sensitive to netilmicin (80%), chloramphenicol (76.4%), and furan (82.6%). All strains of staphylococcus were susceptible to furan, gentamicin, chloramphenicol and cefixime. In 66.7% of cases, the isolated strains of staphylococcus were resistant to amoxicillin. ConclusionUrinary tract infection is a common problem in pediatrics. Its management must be early and adequate based on knowledge of the bacterial ecology in order to reduce the risk of long-term renal complications.

Nasal Carriage of Staphylococci among Health Care Workers and Impact of Conventional Decolonisation Methods

Introduction Staphylococci are one of the most common causes of nosocomial infections. The principal route of transmission of Staphylococci is the contaminated hands of health care workers (HCWs). Staphylococci can also be found as part of the nasal microbiota without causing overt disease. So we undertake the present study to estimate the prevalence of asymptomatic nasal carriage of Staphylococci among HCWs and impact of conventional decolonisation methods in a tertiary care hospital in West Bengal. Materials and Methods Nasal swabs were collected from anterior nares of HCWs for culture and antibiotic sensitivity test on day one. HCWs who were found to be carriers of Staphylococci were advised to apply mupirocin ointment to anterior nares twice daily along with chlorhexidinegluconate bath once daily for five days. All HCWs were also advised to practice standard hygiene protocol. All of them were re-tested for nasal swab culture and antibiotic sensitivity on day seven and day twenty eight. Results Nasal carriage of Staphylococci in the first, second and third culture report was found to be 64.28%, 7.14% and 24.49% respectively. Cefotaxime, cotrimoxazole and erythromycin were least effective against Staphylococci. There was variable sensitivity to clindamycin, gentamycin and ciprofloxacin. All strains of Staphylococci were highly sensitive to linezolid. All strains of Staphylococci except MRSA were highly sensitive to vancomycin. Conclusion The present study re-establishes the fact that HCWs carry Staphylococci in their nose in significantly high proportion. So different measures should be undertaken to minimise Staphylococci related nosocomial infections.

Sensitivity of Staphylococcus aureus cultures of different biological origin to commercial bacteriophages and phages of Staphylococcus aureus var. bovis.

Background and Aim:Mastitis, an inflammation of the mammary gland, is an ongoing problem in dairy herds. In this study, we determined the sensitivity of Staphylococcus aureus cultures of different biological origins to commercial bacteriophages and phages of S. aureus var. bovis which were isolated on dairy farms, to create a drug for the treatment of mastitis in cows.Materials and Methods:We used cultures of S. aureus isolated from different habitats, and other types of staphylococci isolated on dairy farms. As antibacterial agents, the commercially available bacteriophages staphylococcal bacteriophage and Intestifag and field strains of phages Phage SAvB07, Phage SAvB08, Phage SAvB12, and Phage SAvB14 were used. Evaluation of their lytic properties was performed using the drip method.Results:The drug Intestifag lysed cultures isolated from human habitats and archival strains of S. aureus No.209-P and S. aureus (ATCC 25923) in 91.8%–100% of cases. Staphylococcal bacteriophage killed 3.6 times fewer cultures of S. aureus isolated from humans than Intestifag and did not affect the growth of archival strains. Neither drug lysed cultures isolated from cows or cultures isolated from dairy products sold in agri-food markets. Phage SAvB14 lysed 92.7±8.3% of S. aureus isolated from the mammary glands of cows and 69.2±6.4% of cultures isolated from dairy products sold in agri-food markets. Phage SAvB12, Phage SAvB08, and Phage SAvB07 lysed 1.2-1.7 times fewer cultures isolated from the mammary glands of cows and 6-18 times fewer cultures isolated from dairy products, compared with Phage SAvB14. Phages of S. aureus var. bovis can infect staphylococcal species such as Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus, and Staphylococcus xylosus. The widest range of hosts was found for Phage SAvB14, which indicates its polyvalence.Conclusion:The biological origin of staphylococcal strains must be considered when developing effective phage therapy. Phage SAvB14 appears to be a good candidate for the development of a drug for the treatment of mastitis in cows.

In vitro antioxidant and antibacterial activities of phenolic and alkaloid extracts of Laurus nobilis

Laurus nobilis one of medicinal and aromatic plant endemic to the Mediter-ranean region. It is highly appreciated for the condiment benefits of its leaves. Due to its richness in bioactive compounds, the leaves are also used in traditional therapy to treat several infectious diseases. Phenolic com-pounds and alkaloids are particularly important because they are used in many pharmaceutical, food supplement, and cosmetic fields. The presence of phenolic compounds and alkaloids in L. nobilis leaves attracted our atten-tion due to their various functions such as antioxidant capacity and antibac-terial properties. The main objective of this study was to determine antioxi-dant and antibacterial activities of phenolic and alkaloid extracts of L. nobilis. The quantification of antioxidant substances allowed obtaining phenolic compounds content of 86.46 EAG mg/g and a total alkaloids yield of 700 μg/g. The results of antioxidant activity show that, although the alkaloid concen-trations are low, their antioxidant power is higher than phenolic compounds. The results of antibacterial activity of L. nobilis extracts revealed that the highest inhibition was recorded for alkaloid extract against staphylococcal strains responsible for food poisoning. However, L. nobilis phenolic com-pounds showed better activity against phytopathogenic strains associated particularly with potato rot.

Antimicrobial Susceptibility Patterns and Resistance Trends of Staphylococcus aureus and Coagulase-Negative Staphylococci Strains Isolated from Ocular Infections.

Ocular bacterial infections represent a serious problem that affecting people of all age and genders. These infections can lead to visual impairment and blindness if not properly treated. The current study evaluates the antimicrobial resistance profiles and the resistance trend of both Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CoNS), the main pathogens involved in eye infections. A total of 322 isolates of S. aureus and CoNS, were collected from patients with bacterial conjunctivitis and keratitis at the “Luigi Vanvitelli” University Hospital of Campania in Naples, Italy, between 2017 and 2020. The isolated bacteria showed a high percentage of resistance to methicillin and other antibiotics commonly used for the treatment of ocular infections. Trends in antibiotic resistance were not encouraging, recording—especially among CoNS strains—an increase of more than 20% in resistance to methicillin and aminoglycosides during the study period. Instead, the resistance rates to tetracycline had a significant decrease in CoNS isolates while no changes in their susceptibility to fluoroquinolones and macrolides were observed. However, all isolates showed no resistance to trimethoprim/sulfamethoxazole and chloramphenicol. In this scenario, preventive identification of the infection causative agents and the evaluation of the antimicrobial susceptibility patterns are essential to set up an ocular infection effective drug treatment and also prevent antibiotic resistance.

Characterization of biofilms and antimicrobial resistance of coagulase-negative Staphylococcus species involved with subclinical mastitis.

Biofilm formation is a central feature to guarantee staphylococcal persistence in hosts and is associated with several diseases that are difficult to treat. In this research paper, biofilm formation and antimicrobial susceptibility were investigated in staphylococcal strains belonging to several species. These strains were isolated from the milk of cows with subclinical mastitis and most of them were coagulase-negative, with the prevalence of Staphylococcus chromogenes. High genetic diversity was observed among the strains by pulsed field gel electrophoresis. Antimicrobial resistance was assessed by disk diffusion and more than 50% of the strains were resistant to ampicillin and penicillin G, with multi-resistance profiles (13.6%) also being observed. Most strains (65.9%) formed biofilms when cultivated in BHI supplemented with 1% glucose. Most strains (72.7%) carried the intercellular adhesion gene (icaA), while less than half (36.3%) carried the biofilm-associated protein gene (bap). Concentrations of up to 10xMIC of erythromycin and tetracycline were not sufficient to suppress cell viability in preformed biofilms. Our results revealed that a genetically diverse group of biofilm-forming Staphylococcus species can be involved in subclinical mastitis. Since high antimicrobial concentrations cannot eradicate biofilm cells in vitro, their use in dairy animals may be ineffective in controlling infections, while supporting selection of resistant microorganisms. These data reinforce the need for alternative therapies aiming at disrupting biofilms for effective disease control.

Phenotypic characterization of antimicrobial drug resistance of Staphylococcus aureus and S. epidermidis strains isolated from various community infections in Oum El Bouaghi city, Algeria

Abstract. Rahmani A, Meradi L, Malawi K, Khanfouf F. 2021. Phenotypic characterization of antimicrobial drug resistance of Staphylococcus aureus and S. epidermidis strains isolated from various community infections in Oum El Bouaghi city, Algeria. Biodiversitas 22: 2665-2671. In Algeria most community infections caused by Staphylococcus epidermidis and Staphylococcus aureus present resistance to several antibiotics and induce therapeutic failures. The aim of this study is the characterization and the comparison of antimicrobial resistance of Staphylococcus strains isolated from community infection in Oum El Bouaghi city, Algeria. Species identification was realized by conventional biochemical tests and the determination of antibiotics susceptibility pattern was realized by using the agar disk diffusion method, according to the recommendations of the French Society for Microbiology (FSM, 2019). A total of 102 Staphylococci strains were obtained from clinical samples, with a frequency of isolation of 57,8% for S. epidermidis and 42,2% for S. aureus, both strains present a resistance for most used antibiotics, the higher resistance was found for oxacillin in both strains with 25,6% for S. aureus and 42,4% for S. epidermidis. Multidrug-Resistance (MDR) phenotype was detected in 37,3% of S. epidermidis and 14% in S. aureus strains. In Algeria, new control policies should be adopted to prevent the further spread of antimicrobial-resistant strains, especially in the community

Intracellular persistence of Staphylococcus aureus in endothelial cells is promoted by the absence of phenol-soluble modulins

ABSTRACT A large proportion of clinical S. aureus isolates that carry an inactive Agr system are associated with persistent infection that is difficult to treat. Once S. aureus is inside the bloodstream, it can cross the endothelial barrier and invade almost every organ in the human body. Endothelial cells can either be lysed by this pathogen or they serve as a niche for its intracellular long-term survival. Following phagocytosis, several vesicles such as phagosomes and autophagosomes, target intracellular S. aureus for elimination. S. aureus can escape from these vesicles into the host cytoplasm through the activation of phenol-soluble modulins (PSMs) αβ. Thereafter, it replicates and lyses the host cell to disseminate to adjacent tissues. Herein we demonstrate that staphylococcal strains which lack the expression of PSMs employ an alternative pathway to better persist within endothelial cells. The intracellular survival of S. aureus is associated with the co-localization of the autophagy marker LC3. In cell culture infection models, we found that the absence of psmαβ decreased the host cell lysis and increased staphylococcal long-term survival. This study explains the positive selection of agr-negative strains that lack the expression of psmαβ in chronic infection due to their advantage in surviving and evading the clearance system of the host.

Multisubstituted pyrimidines effectively inhibit bacterial growth and biofilm formation of Staphylococcus aureus

Biofilms are multicellular communities of microorganisms that generally attach to surfaces in a self-produced matrix. Unlike planktonic cells, biofilms can withstand conventional antibiotics, causing significant challenges in the healthcare system. Currently, new chemical entities are urgently needed to develop novel anti-biofilm agents. In this study, we designed and synthesized a set of 2,4,5,6-tetrasubstituted pyrimidines and assessed their antibacterial activity against planktonic cells and biofilms formed by Staphylococcus aureus. Compounds 9e, 10d, and 10e displayed potent activity for inhibiting the onset of biofilm formation as well as for killing pre-formed biofilms of S. aureus ATCC 25923 and Newman strains, with half-maximal inhibitory concentration (IC50) values ranging from 11.6 to 62.0 µM. These pyrimidines, at 100 µM, not only decreased the number of viable bacteria within the pre-formed biofilm by 2–3 log10 but also reduced the amount of total biomass by 30–50%. Furthermore, these compounds were effective against planktonic cells with minimum inhibitory concentration (MIC) values lower than 60 µM for both staphylococcal strains. Compound 10d inhibited the growth of S. aureus ATCC 25923 in a concentration-dependent manner and displayed a bactericidal anti-staphylococcal activity. Taken together, our study highlights the value of multisubstituted pyrimidines to develop novel anti-biofilm agents.

SEARCH FOR BIOLOGICALLY ACTUVE SUBSTANCES WITH ANTIMICROBIAL AND ANTIBIOTIC POTENTIATING PROPERTIES AMOUNG MEMBERS OF THE GENUS ARTEMISIA AGAINTS THE MAIN PATHOGENS OF INFECTIOUS SKIN LESIONS

Abstract. Active components of the genus Artemisia show a wide range of antimicrobial effect against most bacterial pathogens. In addition, artemisin isolated from wormwood is used to treat chloroquine-resistant malaria. Antimicrobial and antibiotic-potentiating effects of eight aqueous ethanolic extracts (40 %, 70 % and 90 %) aerial part of the genus Artemisia aqueous against S. aureus and S. epidermidis strains with various types of resistance to macrolides, lincosamides, tetracyclines and fluoroquinolones isolated from outpatients with different forms of pyoderma have been researched with agar diffusion micromethod. Determination of effective antimicrobial concentrations of antimicrobials and test extracts against staphylococci have been performed with serial dilutions micromethod. The statistical program "Statistica", computer programs UTHSCSA Image Tool 3.0 and Microsoft Office Excel 2016 have been used for statistical processing of microbiological research results. The pronounced antimicrobial effect of the wormwood extract Artemisia dracunculus L. (MIC 125.0 - 250.0 μg/ml) against all S. aureus and S. epidermidis test strains has been established. Other studied extracts showed much weaker antimicrobial effect (MIC 1000.0 - 1500.0 μg/ml). It was found that the species of staphylococci and the phenotype of resistance of test strains do not affect antimicrobial activity of the studied extracts. We have found that there is no clear сorrelation between antimicrobial properties of the studied extracts and the phenotype of resistance of staphylococci test-strains. Extracts were equally effective against staphylococcal strains with low level of resistance by efflux of antimicrobial drug and skin isolates with chromosomal resistance. The greatest resistance to BAC of the studied extracts was showed by test strains with a high level of resistance to antibiotics of MLS-group and tetracycline, exhibiting sensitivity only to tarragon wormwood.
 Active components of 70, 90 % common mugwort extract Artemisia vulgaris L. (increase of the inhibition zone up to 117 – 142 %, p<0.05) and southern wormwood extract (increase of the inhibition zone up to 50 – 59 % and 74 – 122 %, respectively, p<0.05) showed dose-dependent synergistic interaction with erythromycin. Common mugwort extract (70 %) showed synergistic interaction with ¼ MIC of tetracycline (increase of the inhibition zone up to 100 %) against strains with combined resistance to all studied antimicrobials. For the study we used crude total extracts of medicinal plants (40 %, 70 % and 90 % ethanol), so we expect their significantly higher antimicrobial effect against staphylococcal strains while optimizing the extraction process and subsequent purification. It should be noted that 90 % aqueous ethanol extracts showed significantly better antimicrobial properties compared to 40 % and 70 % extracts. Active compounds of tarragon wormwood Artemisia dracunculus L. extract show pronounced antimicrobial effect against S. aureus and S. epidermidis strains, the main causative agents of infectious skin lesions, with different types of resistance to macrolides, lincosamides, tetracyclines and fluoroquinolones. Dose-dependent synergistic interaction with macrolides of common mugwort Artemisia vulgaris L. extracts and southern wormwood Artemisia abrotanum L. extract with macrolides (erythromycin) and tetracycline has been revealed.

Profiles of coagulase-positive and -negative staphylococci in retail pork: prevalence, antimicrobial resistance, enterotoxigenicity, and virulence factors.

The present study aimed to investigate the occurrence and species of coagulase-positive staphylococci (CoPS) and coagulase-negative staphylococci (CoNS) in retail pork meat samples collected during nationwide monitoring. The staphylococcal isolates were characterized for antimicrobial and zinc chloride resistance and enterotoxigenic potential. A total of 260 pre-packaged pork meat samples were collected from 35 retail markets in 8 provinces in Korea for isolation of staphylococci. Antimicrobial and zinc chloride resistance phenotypes, and genes associated with the resistance phenotypes were determined on the isolates. Furthermore, the presence and distribution of 19 staphylococcal enterotoxin (SE) genes and enterotoxin-like genes among the pork-associated staphylococci were determined by multiplex PCR-based assays using the specific primer sets. A total of 29 staphylococcal strains (29/260, 11.1%) were isolated from samples of retail pork meat, 24 (83%) of which were CoNS. The four CoNS species identified were S. saprophyticus (n = 16, 55%), S. sciuri (n = 3, 10%), S. warneri (n = 3, 10%), and S. epidermidis (n = 2, 7%). Among the 29 isolates, four methicillin-resistant CoNS (MR-CoNS; three S. sciuri and one S. epidermidis) and one methicillin-resistant CoPS (MR-CoPS; one S. aureus) were identified. In addition, a relatively high level of tetracycline (TET) resistance (52%) was confirmed in CoNS, along with a predominant distribution of tet(K). The most prevalent SEs were sep (45%) and sen (28%), which were carried by 81% of S. saprophyticus. These findings suggest that CoNS, especially S. saprophyticus strains, in raw pork meat could be a potential risk factor for staphylococcal food poisoning (SFP), and therefore, requires further investigation to elucidate the role of SEls in SFP and virulence of the pathogen. Our results also suggest that CoNS from raw pork meat may act as a source for transmission of antimicrobial resistance genes such as SCCmec and tet(K).

The Study of Persistence of S. epidermidis and S. haemolyticus in a Children’s Hospital

Introduction: Staphylococcal infections rank high among healthcare-associated infections. Coagulase-negative staphylococci, especially S. epidermidis and S. haemolyticus, often induce inflammatory processes in newborns. In this regard, it is important to study the persistence of these microorganisms in pediatric hospitals using intraspecific differentiation based on the comparison of spectra of their extracellular proteins. Our objective was to study circulation of S. epidermidis and S. haemolyticus strains in a children’s hospital by electrophoretyping of their extracellular proteins. Materials and methods: We studied 277 strains of S. haemolyticus and 267 strains of S. epidermidis isolated from patients and various objects of the hospital environment by obtaining extracellular proteins of the isolates, analyzing them using polyacrylamide gel electrophoresis, and determining their antibiotic resistance and ability to form biofilms. Results: The analysis of electrophoregrams of extracellular proteins of staphylococci revealed groups of identical strains. Isolates from different patients were combined into 21 S. haemolyticus groups comprising of 69 strains and 13 groups of S. epidermidis comprising of 38 strains. All the cultures were methicillin-resistant, with the exception of one group of two S. haemolyticus strains. More than half of the cultures grouped by spectra of extracellular proteins were multidrug resistant. The absolute majority of S. haemolyticus strains (97.2 %) and three quarters of S. epidermidis strains (76.0 %) were able to form biofilms. The average values of the degree of film formation in S. haemolyticus strains were significantly higher than those in S. epidermidis. Conclusions: Of all the studied cultures of staphylococci, 25 % of strains and 14 % of S. epidermidis strains persisted and were endemic in the children’s hospital, including 88.4 % of hemolytic and 42.1 % of epidermal staphylococcus strains for more than a month, and 21.7 % of S. haemolyticus and 21.1 % of S. epidermidis strains for almost a year. The strains were resistant to methicillin, and the isolates of S. haemolyticus had a high ability to form biofilms.

Study of Antibiotic Resistance Pattern of Staphylococcus epidermidis strains isolated from the Laboratory

ABSTRACT: Staphylococcus epidermidis (S. epidermidis) is the Gram-positive strain which is one of the major causes of laboratory acquired infections. Infections caused by staphylococcus strains are becoming more demanding to treat because many of the strains are resistant to the antibiotics and chemotherapeutic agents. The aim of this study was to determine the antibiotic susceptibility of isolates of S. epidermidis which had been isolated from the microbiology laboratory of Lahore Garrison University, Lahore. Antibiotic Sensitivity against many antibiotics such as TPZ (tazobactum), ME (methicillin), CX (cefoxitin), P (penicillin), CTX (Cefotaxime), CEP (Cefepime) was determined for the identification of the most effective antibiotics against the infectious strains of S. epidermidis and zone of inhibition was measured. The results showed that out of 10 isolates, all the isolates were resistant against ME, while 9 of them were susceptible against TPZ. A remarkable difference was observed in the susceptibility pattern of S. epidermidis against TPZ rather than that of ME. Therefore, TPZ was the most effective antibiotic against the S. epidermidis infections which can be used to treat the infections. According to the present situation, the rampant use of antibiotics shouldbe prevented; otherwise it would become an uncontrollable problem to tackle these super bugs in near future.

Isolation and characterization of bacteriophages from the human skin microbiome that infect Staphylococcus epidermidis.

Phage therapy might be a useful approach for the treatment of nosocomial infections; however, only few lytic phages suitable for this application are available for the opportunistic pathogen, Staphylococcus epidermidis. In the current study, we developed an efficient method to isolate bacteriophages present within the human skin microbiome, by using niche-specific S. epidermidis as the host for phage propagation. Staphylococcus epidermidis was identified on the forehead of 92% of human subjects tested. These isolates were then used to propagate phages present in the same skin sample. Plaques were observable on bacterial lawns in 46% of the cases where S. epidermidis was isolated. A total of eight phage genomes were genetically characterized, including the previously described phage 456. A total of six phage sequences were unique, and spanned each of the major staphylococcal phage families; Siphoviridae (n = 3), Podoviridae (n = 1) and Myoviridae (n = 2). One of the myoviruses (vB_SepM_BE06) was identified on the skin of three different humans. Comparative analysis identified novel genes including a putative N-acetylmuramoyl-L-alanine amidase gene. The host-range of each unique phage was characterized using a panel of diverse staphylococcal strains (n = 78). None of the newly isolated phages infected more than 52% of the S. epidermidis strains tested (n = 44), and non-S. epidermidis strains where rarely infected, highlighting the narrow host-range of the phages. One of the phages (vB_SepM_BE04) was capable of killing staphylococcal cells within biofilms formed on polyurethane catheters. Uncovering a richer diversity of available phages will likely improve our understanding of S. epidermidis-phage interactions, which will be important for future therapy.

Inhibitory properties of Chinese Herbal Formula SanHuang decoction on biofilm formation by antibiotic-resistant Staphylococcal strains

The aim of this study was to explore the effect of Chinese herbal SanHuang decoction (SH) on biofilm formation of antibiotic-resistant Staphylococci on titanium surface, and to explore its mechanism. Biofilm-forming ATCC 35984, ATCC 43300 and MRSE 287 were used in this study. The MICs of SH and vancomycin against Staphylococci were determined by the broth microdilution method. Six groups were designed, namely control group (bacteria cultured with medium), 1/8MIC SH group (1MIC SH was diluted by 1/8 using TSB or saline), 1/4MIC SH group, 1/2MIC SH group, 1MIC SH group and vancomycin group (bacteria cultured with 1MIC vancomycin). The inhibitory effect on bacterial adhesion and biofilm formation were observed by the spread plate method, CV staining, SEM, and CLSM. Real-time PCR was performed to determine the effect of SH on the expression levels of ica AD and ica R gene in ATCC 35984 during the biofilm formation. The strains were found to be susceptible to SH and vancomycin with MIC of 38.75 mg/ml and 2.5 μg/ml, respectively. SH with 1 MIC and 1/2 MIC could inhibit the bacteria adhesion, showing only scattered adhesion from SEM. CLSM showed that SH with 1 MIC and 1/2 MIC inhibited the biofilm formation. The quantitative results of the spread plate method and CV staining showed that there was significant differences between the SH groups (P < 0.05). Further, with an increase in SH concentration, the inhibitory effect became more obvious when compared with control group. Among the groups, vancomycin had the strongest inhibitory effect on bacterial adhesion and biofilm formation (P < 0.01). With an increase in SH concentration, the expression levels of ica AD decreased, and the expression of ica R increased correspondingly (P < 0.05). In conclusions, SH can inhibit the biofilm formation of antibiotic-resistant Staphylococci. Its probable mechanistic activity may be through the inhibition of polysaccharide intercellular adhesin synthesis by down-regulating the expression of ica AD gene.

#82: Osteomyelitis with Panton-Valentine Leukocidin Producing Staphylococcus aureus Strains, Experience in a Tertiary Pediatric Hospital in Mexico City

Abstract Background S. aureus is the most common cause of osteomyelitis in children. Panton-Valentine leucocidin (PVL) is an exotoxin produced by certain S. aureus strains, which can be detected in both methicillin-sensitive and -resistant strains of staphylococci. Pediatric osteomyelitis by PVL producing S. aureus constitute a rare, but highly critical event. They are characterized by a rapid course of marked inflammation, worsening under conservative therapy, and a high rate of recurrence. No information is available on osteomyelitis and Panton-Valentine leukocidin producing S. aureus in Mexico. Objective The aim of this study was to determine the molecular characterization of S. aureus strains isolated in pediatric patients with osteomyelitis and their clinical features in a tertiary hospital in Mexico City. Methods We conducted a prospective study of children admitted for osteomyelitis, between December 2018 and November 2019, at Instituto Nacional de Pediatría. We obtained an informed consent in children under 12 years of age and an informed assent in children over 12. The confirmation of the S. aureus isolates was performed by amplification and analysis of 16S rRNA and nuc genes. The mecA and pvl genes were detected by PCR, the clinical features were obtained at the admission. Results Fifty patients were included and 26 cases of osteomyelitis were diagnosed, 13 were due to staphylococcus aureus genus and 6 due to S. aureus; all of them were methicillin susceptible and two were PVL producers. Both patients had a severe initial presentation, with extensive local abscesses, and one required three surgical procedures and developed septic pulmonary embolism. The two patients received double antimicrobial treatment and required a long therapy interval. Conclusions Osteomyelitis with Panton-Valentine Leukocidin producing S. aureus seems to be more severe. In patients with severe osteomyelitis, it is essential to detect the PVL toxin because they require early surgical intervention and prolonged intravenous therapy. Our findings suggest that the severity of the osteomyelitis is linked with PVL production more than with methicillin resistance due to that all our isolates were methicillin susceptible.