Coagulase-negative staphylococci (CoNS) as a significant etiological factor of laryngological infections: a review

Co-resistance to methicillin and clindamycin among coagulase-negative staphylococci isolates recovered from pet food in Brazil

Pet food have been considered as possible vehicles of bacterial pathogens. The sudden boom of the pet food industry due to the worldwide increase in companion animal ownership calls for pet food investigations. Herein, this study aimed to determine the frequency, antimicrobial susceptibility profile, and molecular characteristics of coagulase-negative staphylococci (CoNS) in different pet food brands in Brazil. Eighty-six pet food packages were screened for CoNS. All isolates were identified at species level by MALDI-TOF MS and species-specific PCR. Antimicrobial susceptibility testing was performed by disc diffusion and broth microdilution (vancomycin and teicoplanin only) methods. The D-test was used to screen for inducible clindamycin phenotype (MLS-B). SCCmec typing and detection of mecA, vanA, vanB, and virulence-encoding genes were done by PCR. A total of 16 (18.6 %) CoNS isolates were recovered from pet food samples. Isolates were generally multidrug-resistant (MDR). All isolates were completely resistant (100 %) to penicillin. Resistances (12.5 % - 75 %) were also observed for fluoroquinolones, sulfamethoxazole-trimethoprim, tetracycline, rifampicin, erythromycin, and tobramycin. Isolates were susceptible to vancomycin (MICs <0.25-1 μg/mL) and teicoplanin (MICs <0.25-4 μg/mL). Intriguingly, 3/8 (37.5 %) CoNS isolates with the ERYRCLIS antibiotype expressed MLS-B phenotype. All isolates harboured blaZ gene. Seven (43.8 %) isolates carried mecA; and among them, the SCCmec Type III was the most frequent (n = 5/7; 71.4 %). Isolates also harboured seb, see, seg, sej, sem, etb, tsst, pvl, and hla toxin virulence-encoding genes (6.3 % - 25 %). A total of 12/16 (75 %) isolates were biofilm producers, while the icaAB gene was detected in an S. pasteuri isolate. Herein, it is shown that pet food is a potential source of clinically important Gram-positive bacterial pathogens. To the best of our knowledge, this is the first report of MLS-B phenotype and MR-CoNS in pet food in Latin America.

Coagulase-negative staphylococci are the main causes of bacterial meningitis in duck

Since September 2018, serious meningitis has been found on some breeding-duck farms in Shandong Province, China. A large number of ducks exhibit severe neurological symptoms. The ducks were randomly selected for laboratory testing. Duck brain samples were collected using standard sterile techniques, and the staphylococci isolates were detected in 404 (70.14%) out of 576 brain samples. A total of 525 coagulase-negative staphylococci (CoNS) strains were isolated, including 6 species: Staphylococcus sciuri (S. sciuri) (67.24%, 353/525), Staphylococcus epidermidis (S. epidermidis) (9.71%, 51/525), Staphylococcus saprophyticus (S. saprophyticus) (8.38%, 44/525), Staphylococcus lentus (S. lentus) (7.62%, 40/525), Staphylococcus haemolyticus (S. haemolyticus) (2.48%, 13/525), and Staphylococcus xylosus (S. xylosus) (4.57%, 24/525). Mixed strain infections were detected in 121 (29.95%) infected presentations. The antimicrobial susceptibility testing indicated that 40.38% of the isolates exhibited multi-drug resistance, and 53.90% of the strains were methicillin-resistant strains by amplification of the methicillin resistance gene (mecA) gene. Through experimental reproduction of the disease, we determined that the CoNS strains were the leading pathogens causing bacterial meningitis in ducks. Although these CoNS strains does not directly cause the death of sick ducks, they still cause large economic losses due to the retarded growth and development of the sick ducks, lower feed returns, and lower grades of processed duck products. The results of this study will contribute to our understanding of the epidemiology and pathogenesis of CoNS and be helpful in the prevention and treatment of the infection.

A Retrospective Descriptive Study of Staphylococcus Species Isolated from Canine Specimens Submitted to a Diagnostic Laboratory in South Africa, 2012-2017

There is a scarcity of published studies on the occurrence of Staphylococcus spp. Among dogs in South Africa. The objective of the study was to characterise the Staphylococcus spp. Isolated from dog samples submitted to a veterinary diagnostic laboratory in South Africa in terms of time, place, and person. This study utilised a dataset of 1627 positive Staphylococcus isolates obtained from a veterinary diagnostic laboratory in South Africa from 2012 to 2017. Out of the 1627 confirmed isolates, 10 different species of Staphylococcus were identified. Among these, 92.0% were classified as coagulase-positive staphylococci (CoPS), 6.0% were coagulase-negative staphylococci (CoNS), and 3.0% were coagulase-variable. Male dogs contributed just over half (53.2%) of the Staphylococcus isolates, while female dogs contributed the remaining 46.8%. The largest proportion of isolates (23.2%) were obtained from dogs aged ≥ 9 years, with the highest number of isolates originating from KwaZulu-Natal Province (45.0%) and the least from Northern Cape Province (0.1%). Out of the total samples included in the records, the majority (46.0%) were skin specimens. The number of Staphylococcus isolates recorded showed limited variation between the seasons (24.3% in autumn, 26.3% in winter, 26.0% in spring, and 24.0% in summer). This study highlighted the diversity of Staphylococcus spp. isolated from dogs, and the burden of staphylococcal carriage among dogs in South Africa. Further research is required to examine the factors that contribute to the observed discrepancies in the proportions of Staphylococcus spp. between the provinces.

Characterization of virulence factors and antimicrobial resistance in Staphylococcus spp. isolated from clinical samples

The virulence factors, antibiotic resistance patterns, and the associated genetic elements have been investigated in Staphylococcus species. A total of 100 strains has been isolated from clinical samples in the Microbiology Laboratory of Hesperia Hospital, Modena, Italy, and identified as Staphylococcus aureus (65), Staphylococcus epidermidis (24), Staphylococcus hominis (3), Staphylococcus saprophyticus (3), and Staphylococcus warneri (5). All the strains were analyzed to determine phenotypic and genotypic characters, notably the virulence factors, the antibiotics susceptibility, and the genetic determinants. The highest percentage of resistance in Staphylococcus spp. was found for erythromycin and benzylpenicillin (87% and 85%, respectively). All S. aureus, two S. epidermidis (8.3%), and one S. saprophyticus (33.3%) strains were resistant to oxacillin. The methicillin resistance gene (mecA) was detected by polymerase chain reaction (PCR) amplification in 65 S. aureus strains and in 3 coagulase-negative staphylococci (CoNS) (8.6%). With regard to the virulence characteristics, all the S. aureus were positive to all virulence tests, except for slime test. Among the CoNS isolates, 19 (79.1%) S. epidermidis and one (33.3%) S. saprophyticus strains resulted positive for the slime test only. The results obtained are useful for a more in-depth understanding of the function and contribution of S. aureus and CoNS antibiotic resistance and virulence factors to staphylococcal infections. In particular, the production of slime is very important for CoNS, a virulence factor frequently found in infections caused by these strains. Further investigations on the genetic relatedness among strains of different sources will be useful for epidemiological and monitoring purposes and will enable us to develop new strategies to counteract the diffusion of methicillin-resistant S. aureus (MRSA) and CoNS strains not only in clinical field, but also in other related environments.

Bacterial contamination of cockroaches in different wards of hospital, restaurant and home

Cockroaches are very capable of mechanically transmitting harmful microorganisms, which is seen to be a severe hazard to the general public's health. The purpose of this study was the evaluation of cockroach bacterial contamination in various locations throughout Babylon. 300 cockroaches were caught from different wards of the hospital, restaurants, and houses. Using PBS buffer, the external surface of the cockroaches was washed to collect bacteria. Standard phenotypic methods were used to identify and classify bacteria. Afterward, the bacterial resistance to different antibiotics was investigated using the Kirby-Bauer disk diffusion susceptibility test. The 200 (66.6 %) American cockroaches including 56 (18.7 %) Blattella germanica and 44 (14.6 %) Blatta orientalis were identified. Noteworthy, 96.6 % of cockroaches were infected with different bacteria. Bacillus strains, coagulase-negative Staphylococci (CoNs), and Escherichia coli were the most frequent among the isolated bacteria. On average, the highest antibiotic resistance was detected to cefotaxime, ampicillin, cephalothin, and kanamycin. On the other hand, the isolated bacteria showed high sensitivity to gentamicin, nitrofurantoin, tetracycline, trimethoprim/sulfamethoxazole (SXT), and chloramphenicol. high antibiotic resistance in bacteria isolated from different wards of the hospital and the high potential of transmission of these bacteria by cockroaches is a serious warning for the health of society.

Current types of staphylococcal cassette chromosome mec (SCCmec) in clinically relevant coagulase-negative staphylococcal (CoNS) species

Coagulase-negative staphylococci (CoNS) colonize human skin and mucosal membranes, which is why they are considered harmless commensal bacteria. Two species, Staphylococcus epidermidis and Staphylococcus haemolyticus belong to the group of CoNS species and are most frequently isolated from nosocomial infections, including device-associated healthcare-associated infections (DA-HAIs) and local or systemic body-related infections (FBRIs). Methicillin resistance, initially described in Staphylococcus aureus, has also been reported in CoNS species. It is mediated by the mecA gene within the staphylococcal cassette chromosome (SCCmec). SCCmec typing, primarily using PCR-based methods, has been employed as a molecular epidemiological tool. However, the introduction of whole genome sequencing (WGS) and next-generation sequencing (NGS) has enabled the identification and verification of new SCCmec types. This review describes the current distribution of SCCmec types, subtypes, and variants among CoNS species, including S. epidermidis, S. haemolyticus, and S. capitis. The literature review focuses on recent research articles from the past decade that discuss new combinations of SCCmec in coagulase-negative Staphylococcus. The high genetic diversity and gaps in CoNS SCCmec annotation rules underscore the need for an efficient typing system. Typing SCCmec cassettes in CoNS strains is crucial to continuously updating databases and developing a unified classification system.

Within-Host Diversity of Coagulase-Negative Staphylococci Resistome from Healthy Pigs and Pig Farmers, with the Detection of cfr-Carrying Strains and MDR-S. borealis

The ecology and diversity of resistome in coagulase-negative staphylococci (CoNS) from healthy pigs and pig farmers are rarely available as most studies focused on the livestock-associated methicillin-resistant S. aureus. This study aims to characterize the antimicrobial resistance (AMR) mechanisms, intra-host species diversity (more than one species in a host), and intra-species AMR diversity (same species with more than one AMR profile) in CoNS recovered from the nasal cavities of healthy pigs and pig farmers. One-hundred-and-one CoNS strains previously recovered from 40 pigs and 10 pig farmers from four Spanish pig farms were tested to determine their AMR profiles. Non-repetitive strains were selected (n = 75) and their AMR genes, SCCmec types, and genetic lineages were analyzed by PCR/sequencing. Of the non-repetitive strains, 92% showed a multidrug resistance (MDR) phenotype, and 52% were mecA-positive, which were associated with SCCmec types V (46.2%), IVb (20.5%), and IVc (5.1%). A total of 28% of the pigs and pig farmers had intra-host species diversity, while 26% had intra-species AMR diversity. High repertoires of AMR genes were detected, including unusual ones such as tetO, ermT, erm43, and cfr. Most important was the detection of cfr (in S. saprophyticus and S. epidermidis-ST16) in pigs and pig farmers; whereas MDR-S. borealis strains were identified in pig farmers. Pig-to-pig transmission of CoNS with similar AMR genes and SCCmec types was detected in 42.5% of pigs. The high level of multidrug, within-host, and intra-species resistome diversity in the nasal CoNS highlights their ability to be AMR gene reservoirs in healthy pigs and pig farmers. The detection of MDR-S. borealis and linezolid-resistant strains underscore the need for comprehensive and continuous surveillance of MDR-CoNS at the pig farm level.

Analysis of Retrospective Laboratory Data on the Burden of Bacterial Pathogens Isolated at the National Veterinary Research Institute Nigeria, 2018-2021

Farm animals harbour bacterial pathogens, which are often viewed as important indicators of animal health and determinants of food safety. To better understand the prevalence and inform treatment, we audited laboratory data at the Bacteriology Laboratory of the NVRI from 2018-2021. Antibiotics were classified into seven basic classes: quinolones, tetracyclines, beta-lactams, aminoglycosides, macrolides, nitrofuran, and cephalosporins. Trends were analysed using a generalised linear model with a log link function for the Poisson distribution, comparing proportions between years with an offset to account for the variability in the total number of organisms per year. Avian (73.18%) samples were higher than any other sample. The major isolates identified were Escherichia. coli, Salmonella spp., Klebsiella spp., Staphylococcus spp., Proteus spp., and Pseudomonas spp. We found that antimicrobial resistance to baseline antibiotics increased over the years. Of particular concern was the increasing resistance of Klebsiella spp. to cephalosporins, an important second-generation antibiotic. This finding underscores the importance of farm animals as reservoirs of pathogens harbouring antimicrobial resistance. Effective biosecurity, surveillance, and frugal use of antibiotics in farms are needed because the health of humans and animals is intricately connected.

Oral and gut microbial biomarkers of susceptibility to respiratory tract infection in adults: A feasibility study

We conducted a feasibility cohort study which aimed to recruit and retain adults from the community to collect saliva (oral) and stool (gut) samples at three time points, at the start of the study (baseline), during a respiratory tract infection (RTI) and post-RTI. Community RTIs place a huge burden on health care services, and a non-invasive microbial diagnostic tool to predict the most vulnerable to respiratory infection would be ideal. To this aim, we analysed oral-gut baseline samples comparing those who reported RTI symptoms to those who remained healthy throughout the study for microbial biomarkers of respiratory susceptibility. Amplicon sequence variants (ASV) were identified by 16S sequence profiling to reveal oral-gut microbes. Reverse transcriptase-polymerase chain reaction (RT-PCR) was applied to target common respiratory microbes. Two general practices were recruited, and the participant recruitment rate was 1.3%. A total of 40 adult participants were retained, of which 19 acquired an RTI whereas 21 remained healthy. In healthy baseline oral and gut samples, ASVs from participants with RTI symptoms compared to those who remained healthy were similar with a high relative abundance of Streptococcus sp., and Blautia sp., respectively. Linear discriminant analysis effect size (LEfSe) revealed baseline oral microbes differed, indicating participants who suffered RTI symptoms had enhanced Streptococcus sobrinus and Megamonas sp., and depletion of Lactobacillus salivarius, Synergistetes, Verrucomicrobia and Dethiosulfovibrio. Furthermore, a random forest model ranked Streptococcus (4.13) as the highest mean decrease in accuracy (MDA) and RT-PCR showed a higher level of carriage of coagulase-negative Staphylococcus. Baseline core gut microbes were similar in both participant groups whereas LEfSe analysis revealed enhanced Veillonella, Rikenellaceae, Enhydobacteria, Eggerthella and Xanthomonsdales and depleted Desulfobulbus and Coprobacillus. Sutterella (4.73) had a high MDA value. Overall, we demonstrated the feasibility of recruiting and retaining adult participants from the community to provide multiple biological samples for microbial profiling. Our analyses identified potential oral-gut microbial biomarkers of respiratory infection susceptibility in otherwise healthy participants.

Prevalence of Culturable Bacteria and Yeasts in the Nasopharynx Microbiota during the Physiological Course of Pregnancy

The aim of the study was to compare the prevalence of the nasopharyngeal carriage of culturable microorganisms in the microbiota of asymptomatic women with a physiological pregnancy (PW) and nonpregnant women (NPW). Nasopharyngeal swabs were collected from 53 PW and 30 NPW to detect bacterial and fungal colonization. Isolates were identified using the culture method and the MALDI-TOF MS technique. The nasopharyngeal microbiota (NPM) partially differed between PW and NPW. These differences in the frequency of nasopharyngeal colonization between the PW and NPW groups were not statistically significant (p > 0.05); all cases were colonized by bacteria and only two cases in the PW group were colonized by yeasts, namely, Rhodotorula spp. High levels of staphylococcal colonization, including predominantly coagulase-negative staphylococci and S. aureus in the nasopharyngeal sample, were present in both groups. The reduced number of Gram-negative rods colonized in the cases studied was seen in samples from the NPW group, particularly with Enterobacterales, and anaerobic Cutibacterium spp. were isolated only in the PW group (p < 0.05). Moreover, a higher carriage rate of Enterobacter aerogenes colonization was statistically significant (p < 0.05) and correlated with the NPW group. Pregnancy may disturb the composition of the NPM represented by commensals and opportunistic bacteria and promote yeast colonization as compared to nonpregnant women.

Antimicrobial resistome of coagulase-negative staphylococci from nasotracheal cavities of nestlings of Ciconia ciconia in Southern Spain: Detection of mecC-SCCmec type-XI-carrying S. lentus

The antimicrobial resistance (AMR) genes of 268 non-duplicated coagulase-negative staphylococci (CoNS) previously obtained from nasotracheal cavities of nestling storks were characterized. They included S. sciuri isolates (n = 191), and non-sciuri-CoNS isolates (NSc-CoNS, n = 77). All S. sciuri carried the intrinsic salA gene (for clindamycin-resistance) and so, clindamycin was not considered for general analysis in this species. About 71.7%/41.6% of the S. sciuri/NSc-CoNS isolates were susceptible to all antibiotics tested; moreover, 14.1%/16.9% and 3.1%/20.8% of S. sciuri/NSc-CoNS showed single antibiotic resistance and multidrug resistance (MDR) phenotype, respectively. Of the ten mecA-positive CoNS isolates, six were associated with SCCmec types-III, -IV or -V elements. Remarkably was the detection of one MDR-S. lentus isolate carrying both mecA and mecC genes, as well as the SCCmec type-XI element. MDR-CoNS was relatively higher in nestlings of parent storks foraging in landfills (21.3%) than those in natural areas (9.7%) (χ² = 3.421, df=1, p = 0.064). AMR phenotypes (and genes detected) include penicillin (blaZ, bla_ARL), erythromycin-clindamycin-constitutive (ermA, ermC, ermT), clindamycin (lnuA, salA, vgaA), erythromycin (msrA, mphC), tetracycline (tetK, tetL, tetM), tobramycin (ant4'), tobramycin-gentamicin (aac6'-aph2″), sulfamethoxazole-trimethoprim (dfrA, dfrG, dfrK), chloramphenicol (fexA, fexB, catPC221), and mupirocin (mupA). Interestingly, one S. epidermidis isolate carried the ermT gene. About 29.9% of nestlings harboured more than one non-duplicated CoNS (with varied 2-5 AMR profiles). This study demonstrated that most of the CoNS isolates were susceptible to all the antibiotics tested (63.1%). However, AMR genes of public health importance were found, including the mecC-mediated methicillin resistance trait.

Antimicrobial Resistance: Two-Component Regulatory Systems and Multidrug Efflux Pumps

The number of multidrug-resistant bacteria is rapidly spreading worldwide. Among the various mechanisms determining resistance to antimicrobial agents, multidrug efflux pumps play a noteworthy role because they export extraneous and noxious substrates from the inside to the outside environment of the bacterial cell contributing to multidrug resistance (MDR) and, consequently, to the failure of anti-infective therapies. The expression of multidrug efflux pumps can be under the control of transcriptional regulators and two-component systems (TCS). TCS are a major mechanism by which microorganisms sense and reply to external and/or intramembrane stimuli by coordinating the expression of genes involved not only in pathogenic pathways but also in antibiotic resistance. In this review, we describe the influence of TCS on multidrug efflux pump expression and activity in some Gram-negative and Gram-positive bacteria. Taking into account the strict correlation between TCS and multidrug efflux pumps, the development of drugs targeting TCS, alone or together with already discovered efflux pump inhibitors, may represent a beneficial strategy to contribute to the fight against growing antibiotic resistance.

Leaky barriers to gene sharing between locally co-existing coagulase-negative Staphylococcus species

Coagulase-negative Staphylococcus (CoNS) are opportunistic pathogens implicated in many human and animal infections. The evolutionary history of CoNS remains obscure because of the historical lack of recognition for their clinical importance and poor taxonomic sampling. Here, we sequenced the genomes of 191 CoNS isolates representing 15 species sampled from diseased animals diagnosed in a veterinary diagnostic laboratory. We found that CoNS are important reservoirs of diverse phages, plasmids and mobilizable genes encoding antimicrobial resistance, heavy metal resistance, and virulence. Frequent exchange of DNA between certain donor-recipient partners suggests that specific lineages act as hubs of gene sharing. We also detected frequent recombination between CoNS regardless of their animal host species, indicating that ecological barriers to horizontal gene transfer can be surmounted in co-circulating lineages. Our findings reveal frequent but structured patterns of transfer that exist within and between CoNS species, which are driven by their overlapping ecology and geographical proximity.

Bacterial Contamination of Collected Cockroaches and Determination Their Antibiotic Susceptibility in Khorramabad City, Iran

Background

Cockroaches are one of the most important carriers of pathogenic microorganisms. Therefore, the presence of cockroaches in public places, especially in hospitals, homes, and restaurants, is dangerous, and threatens the health of society, people, and the environment. The aim of this study was evaluation of bacterial contamination of cockroaches and the sensitivity of these bacteria to various antibiotics, captured from Khorramabad City, Iran.

Methods

This descriptive cross-sectional study was performed on 150 cockroaches collected from hospital environments, homes, and restaurants in Khorramabad. The outer surface of the cockroaches was washed with physiological saline. The suspension was centrifuged for 5 minutes at 2000rpm. Isolation and identification of bacteria was performed using phenotypic methods. Antibiotic susceptibility testing was performed by disk diffusion method according to Clinical and Laboratory Standard Institute (CLSI) guideline.

Results

A total of 100 American cockroaches (66.66%), 28 B. germanica (18.66%) and 22 Blatta orientalis (14.66%) were identified. In total, 97.33% of the collected cockroaches were infected with bacteria. The most bacterial infection of the cockroaches was Escherichia coli, coagulase-negative Staphylococci and Bacillus respectively. The overall results of the antibiogram test showed that the identified bacteria were resistant to cephalothin, ampicillin, cefotaxime, and kanamycin antibiotics, semi-sensitive to ciprofloxacin and sensitive to tetracycline, gentamicin, nitrofurantoin, Trimethoprim/sulfamethoxazole, and Chloramphenicol.

Conclusion

Infection of cockroaches with pathogenic bacterial agents in hospital, residential, and restaurant environments, as well as the observation of bacterial resistance to some common antibiotics is worrying.

Prevalence and Potential Risk Factors for the Acquisition of Antibiotic-Resistant Staphylococcus spp. Bacteria Among Pastoralist Farmers in Kajiado Central Subcounty, Kenya

Antimicrobial resistance (AMR) is a growing health problem globally. To address this challenge, there is a need to generate baseline data on the prevalence and AMR profile of the main disease-causing bacteria. Here, we interrogated the prevalence of bacteria in the nasal cavity of healthy pastoralists in Kajiado Central Subcounty, Kenya, and the occurrence of AMR in Staphylococcus isolates among the study subjects. Nasal swabs from 176 pastoralists were cultured, and the bacteria isolates identified using standard phenotypic and biochemical bacteriological methods. Among the obtained 195 isolates, the most prevalent isolates were coagulase-negative Staphylococcus (CoNS) (44.9%), followed by Enterococci spp. (43.2%) while Staphylococcus aureus prevalence was 8%. Antimicrobial sensitivity of the Staphylococcus spp. isolates to 14 antibiotics representing six antibiotic groups was undertaken using the Kirby-Bauer disk diffusion method. Among the CoNS, the highest resistance was reported in amoxicillin (78.7%) and ceftazidime (76%), while the most resistance for S. aureus was reported in ceftazidime (100%), amoxicillin (71.4%), and streptomycin (71.4%). From an administered questionnaire looking at gender, animal contact frequency, history of hospital visitation and antibiotic usage, and habitual intake of raw milk, the study showed that male participants had a higher risk of carrying multiple drug resistant (MDR) bacteria than females (p = 0.02, OR = 1.3). Likewise, habitual intake of raw milk was significantly associated MDR acquisition (p = 0.02, OR = 1.82). This study reveals a high prevalence of AMR Staphylococcus isolates in the study area laying a foundation for further analysis of molecular characterization of the observed resistance as well as the development of interventions that can reduce the occurrence of AMR in the study area.

Comparative Genotypic Analysis of RAPD and RFLP Markers for Molecular Variation Detection of Methicillin-Resistant Staphylococcus aureus Clinical Isolates

Background and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) isolates are associated with various diseases ranged from mild superficial impairments to invasive infections. This study aimed to evaluate the ability of polymerase chain reaction (PCR) based methods namely, restriction fragment length polymorphism (RFLP) of the coa gene and random amplified polymorphic DNA (RAPD), to determine the genetic diversity of MRSA isolates. Materials and Methods: A total of 37 MRSA isolates were conventionally identified depending on their biochemical and microbiological culture characteristics. Genotypic confirmation was based on detection of the associated mecA gene. The genetic variation amongst MRSA isolates was evaluated following the coa gene-based RFLP and RAPD fingerprints. Results: Results illustrated that, the species specific coa gene was detected in all MRSA isolates. The irregular bands intensity, number, and molecular sizes of the PCR amplicons demonstrated the coa gene polymorphism. The incompatible AluI digestion patterns of these amplicons classified the tested MRSA isolates into 20 RFLP patterns which confirm the coa gene polymorphism. Additionally, the PCR-based RAPD analysis showed variable bands number with size range of approximately 130 bp to 4 kbp, which indicated the genetic variation of the tested MRSA isolates as it created 36 variable RAPD banding profiles. Conclusions: coa gene AluI enzymatic restriction sites, amongst the tested MRSA isolates, certify their genetic variation on the basis of the accurate but complicated and relatively expensive coa gene-based RFLP. Conversely, the results verified the excellent ability of the simple and cost-effective PCR-based RAPD analysis to discriminate between MRSA isolates without any preface data about the genome.

Across-Shift Changes in Viable Nasal Bacteria among Waste-Incineration Plant Workers-A Pilot Study

The aim of this pilot study was to assess the time-related changes in viable nasal bacteria concentrations among waste-incineration plant (WIP) workers compared to a group of office building (OB) workers outside the plant. In total, 20 volunteers participated in the study, including 14 WIP and 6 OB workers. WIP workers were divided into two sub-groups: supervisory staff (SVS) and maintenance and repair workers (MRW). Nasal swabs were collected before and after the morning work shift. Airborne bacteria were sampled with a six-stage impactor to assess the bioaerosol size distribution. The analysis showed that a significant, almost three-fold increase in nasal bacterial concentration was found only among WIP workers, and this referred mainly to anaerobic species. The load of anaerobic bacteria at the beginning of work was 12,988 CFU/mL, and after work shift 36,979 CFU/mL (p < 0.01). Significant increases in microbial concentrations was found only in the MRW subgroup, among non-smoking workers only. The results showed increased bacterial concentration in WIP nasal samples for as many as 12 bacterial species, including, e.g., Streptococcus constellatus, Peptostreptococcus spp., E. coli, and P. mirabilis. These preliminary data confirmed that the nasal swab method was helpful for assessment of the workers’ real-time exposure to airborne bacteria.

Whole-Genome Sequence of Multidrug-Resistant Methicillin-Resistant Staphylococcus epidermidis Carrying Biofilm-Associated Genes and a Unique Composite of SCCmec

Staphylococcus epidermidis is part of the normal human flora that has recently become an important opportunistic pathogen causing nosocomial infections and tends to be multidrug-resistant. In this investigation, we aimed to study the genomic characteristics of methicillin-resistant S. epidermidis isolated from clinical specimens. Three isolates were identified using biochemical tests and evaluated for drug susceptibility. Genomic DNA sequences were obtained using Illumina, and were processed for analysis using various bioinformatics tools. The isolates showed multidrug resistance to most of the antibiotics tested in this study, and were identified with three types (III(3A), IV(2B&5), and VI(4B)) of the mobile genetic element SCCmec that carries the methicillin resistance gene (mecA) and its regulators (mecI and mecR1). A total of 11 antimicrobial resistance genes (ARGs) was identified as chromosomally mediated or in plasmids; these genes encode for proteins causing decreased susceptibility to methicillin (mecA), penicillin (blaZ), fusidic acid (fusB), fosfomycin (fosB), tetracycline (tet(K)), aminoglycosides (aadD, aac(6′)-aph(2′’)), fluoroquinolone (MFS antibiotic efflux pump), trimethoprim (dfrG), macrolide (msr(A)), and chlorhexidine (qacA)). Additionally, the 9SE strain belongs to the globally disseminated ST2, and harbors biofilm-formation genes (icaA, icaB, icaC, icaD, and IS256) with phenotypic biofilm production capability. It also harbors the fusidic acid resistance gene (fusB), which could increase the risk of device-associated healthcare infections, and 9SE has been identified as having a unique extra SCC gene (ccrB4); this new composite element of the ccr type needs more focus to better understand its role in the drug resistance mechanism.

May Staphylococcus lugdunensis Be an Etiological Factor of Chronic Maxillary Sinuses Infection?

Staphylococcus lugdunensis is an opportunistic pathogen found in the healthy human skin microbiome bacterial community that is able to cause infections of diverse localization, manifestation, and course, including laryngological infections, such as necrotizing sinusitis. Chronic maxillary sinusitis is a disease present in up to one third of European and American populations, and its etiology is not fully described. Within this study, we aimed to characterize 18 S. lugdunensis strains recovered from maxillary sinuses and evaluate them as etiological agents of chronic disease. We performed MLST analysis, the complex analysis of both phenotypic and genetic virulence factors, antibiotic susceptibility profiles, and biofilm formation assay for the detection of biofilm-associated genes. Altogether, S. lugdunensis strains were clustered into eight different STs, and we demonstrated several virulence factors associated with the chronic disease. All tested strains were able to produce biofilm in vitro with numerous strains with a very strong ability, and overall, they were mostly susceptible to antibiotics, although we found resistance to fosfomycin, erythromycin, and clindamycin in several strains. We believe that further in-depth analysis of S. lugdunensis strains from different niches, including the nasal one, should be performed in the future in order to reduce infection rate and broaden the knowledge about this opportunistic pathogen that is gaining attention.

Multidrug-Resistant Methicillin-Resistant Coagulase-Negative Staphylococci in Healthy Poultry Slaughtered for Human Consumption

Coagulase-negative staphylococci are commensals that are known to be prevalent in most environments, and they are also an important reservoir of antimicrobial-resistant genes. Staphylococcal infections in animal husbandry are a high economic burden. Thus, we aimed to determine the prevalence and species diversity of methicillin-resistant coagulase-negative staphylococci (MRCoNS) in poultry slaughtered for human consumption and to study the antimicrobial resistance of the isolates. Swab samples were recovered from 220 commercial chickens, homebred chickens and quails. Species identification was performed using MALDI-TOF. Antimicrobial susceptibility testing was performed by the disc diffusion method against 14 antimicrobials. The presence of antimicrobial-resistant genes was investigated by polymerase chain reaction. Totals of 11 (19.6%), 13 (20.3%), and 51 (51%) MRCoNS were isolated from commercial chickens, homebred chickens and quails, respectively. S. lentus was isolated from all homebred chickens, whereas 11 S. lentus and 2 S. urealyticus were isolated from commercial chickens. As for quails, the most prevalent MRCoNS were S. urealyticus. Almost all isolates had a multidrug-resistant profile and carried the mecA gene. Most isolates showed resistance to erythromycin, clindamycin, penicillin, tetracycline, ciprofloxacin and fusidic acid and harbored the ermA, ermB, ermC, mphC tetK, tetL, tetM and tetO genes. This study showed a frequent occurrence of multidrug resistance in MRCoNS isolated from healthy poultry in Portugal.

Investigating Pathogenicity and Virulence of Staphylococcus pettenkoferi: An Emerging Pathogen

Staphylococcus pettenkoferi is a coagulase-negative Staphylococcus identified in 2002 that has been implicated in human diseases as an opportunistic pathogenic bacterium. Its multiresistant character is becoming a major health problem, yet the pathogenicity of S. pettenkoferi is poorly characterized. In this study, the pathogenicity of a S. pettenkoferi clinical isolate from diabetic foot osteomyelitis was compared with a Staphylococcus aureus strain in various in vitro and in vivo experiments. Growth kinetics were compared against S. aureus, and bacteria survival was assessed in the RAW 264.7 murine macrophage cell line, the THP-1 human leukemia monocytic cell line, and the HaCaT human keratinocyte cell line. Ex vivo analysis was performed in whole blood survival assays and in vivo assays via the infection model of zebrafish embryos. Moreover, whole-genome analysis was performed. Our results show that S. pettenkoferi was able to survive in human blood, human keratinocytes, murine macrophages, and human macrophages. S. pettenkoferi demonstrated its virulence by causing substantial embryo mortality in the zebrafish model. Genomic analysis revealed virulence factors such as biofilm-encoding genes (e.g., icaABCD; rsbUVW) and regulator-encoding genes (e.g., agr, mgrA, sarA, saeS) well characterized in S. aureus. This study thus advances the knowledge of this under-investigated pathogen and validates the zebrafish infection model for this bacterium.

Secretory Proteases of the Human Skin Microbiome

The human skin is our outermost layer and serves as a protective barrier against external insults. Advances in next generation sequencing have enabled the discoveries of a rich and diverse community of microbes - bacteria, fungi and viruses that are residents of this surface. The genomes of these microbes also revealed the presence of many secretory enzymes. In particular, proteases which are hydrolytic enzymes capable of protein cleavage and degradation are of special interest in the skin environment which is enriched in proteins and lipids. In this minireview, we will focus on the roles of these skin-relevant microbial secreted proteases, both in terms of their widely studied roles as pathogenic agents in tissue invasion and host immune inactivation, and their recently discovered roles in inter-microbial interactions and modulation of virulence factors. From these studies, it has become apparent that while microbial proteases are capable of a wide range of functions, their expression is tightly regulated and highly responsive to the environments the microbes are in. With the introduction of new biochemical and bioinformatics tools to study protease functions, it will be important to understand the roles played by skin microbial secretory proteases in cutaneous health, especially the less studied commensal microbes with an emphasis on contextual relevance.

Extensive Horizontal Gene Transfer within and between Species of Coagulase-Negative Staphylococcus

Members of the gram-positive bacterial genus Staphylococcus have historically been classified into coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS) based on the diagnostic presentation of the coagulase protein. Previous studies have noted the importance of horizontal gene transfer (HGT) and recombination in the more well-known CoPS species Staphylococcus aureus, yet little is known of the contributions of these processes in CoNS evolution. In this study, we aimed to elucidate the phylogenetic relationships, genomic characteristics, and frequencies of HGT in CoNS, which are now being recognized as major opportunistic pathogens of humans. We compiled a data set of 1,876 publicly available named CoNS genomes. These can be delineated into 55 species based on allele differences in 462 core genes and variation in accessory gene content. CoNS species are a reservoir of transferrable genes associated with resistance to diverse classes of antimicrobials. We also identified nine types of the mobile genetic element SCCmec, which carries the methicillin resistance determinant mecA. Other frequently transferred genes included those associated with resistance to heavy metals, surface-associated proteins related to virulence and biofilm formation, type VII secretion system, iron capture, recombination, and metabolic enzymes. The highest frequencies of receipt and donation of recombined DNA fragments were observed in Staphylococcus capitis, Staphylococcus caprae, Staphylococcus hominis, Staphylococcus haemolyticus, and members of the Saprophyticus species group. The variable rates of recombination and biases in transfer partners imply that certain CoNS species function as hubs of gene flow and major reservoir of genetic diversity for the entire genus.

Ecology and Genetic Lineages of Nasal Staphylococcus aureus and MRSA Carriage in Healthy Persons with or without Animal-Related Occupational Risks of Colonization: A Review of Global Reports

In this conceptual review, we thoroughly searched for appropriate English articles on nasal staphylococci carriage among healthy people with no reported risk of colonization (Group A), food handlers (Group B), veterinarians (Group C), and livestock farmers (Group D) published between 2000 and 2021. Random-effects analyses of proportions were performed to determine the pooled prevalence of S. aureus, MRSA, MRSA-CC398, and MSSA-CC398, as well as the prevalence of PVL-positive S. aureus from all eligible studies. A total of 166 eligible papers were evaluated for Groups A/B/C/D (n = 58/31/26/51). The pooled prevalence of S. aureus and MRSA in healthy humans of Groups A to D were 15.9, 7.8, 34.9, and 27.1%, and 0.8, 0.9, 8.6, and 13.5%, respectively. The pooled prevalence of MRSA-CC398 nasal carriage among healthy humans was as follows: Group A/B (<0.05%), Group C (1.4%), Group D (5.4%); and the following among Group D: pig farmers (8.4%) and dairy farmers (4.7%). The pooled prevalence of CC398 lineage among the MSSA and MRSA isolates from studies of the four groups were Group A (2.9 and 6.9%), B (1.5 and 0.0%), C (47.6% in MRSA), and D (11.5 and 58.8%). Moreover, MSSA-CC398 isolates of Groups A and B were mostly of spa-t571 (animal-independent clade), while those of Groups C and D were spa-t011 and t034. The MRSA-CC398 was predominately of t011 and t034 in all the groups (with few other spa-types, livestock-associated clades). The pooled prevalence of MSSA and MRSA isolates carrying the PVL encoding genes were 11.5 and 9.6% (ranges: 0.0-76.9 and 0.0-28.6%), respectively. Moreover, one PVL-positive MSSA-t011-CC398 isolate was detected in Group A. Contact with livestock and veterinary practice seems to increase the risk of carrying MRSA-CC398, but not in food handlers. Thus, this emphasizes the need for integrated molecular epidemiology of zoonotic staphylococci.

First Case of Staphylococci Carrying Linezolid Resistance Genes from Laryngological Infections in Poland

Linezolid is currently used to treat infections caused by multidrug-resistant Gram-positive cocci. Both linezolid-resistant S. aureus (LRSA) and coagulase-negative staphylococci (CoNS) strains have been collected worldwide. Two isolates carrying linezolid resistance genes were recovered from laryngological patients and characterized by determining their antimicrobial resistance patterns and using molecular methods such as spa typing, MLST, SCCmec typing, detection of virulence genes and ica operon expression, and analysis of antimicrobial resistance determinants. Both isolates were multidrug resistant, including resistance to methicillin. The S. aureus strain was identified as ST-398/t4474/SCCmec IVe, harboring adhesin, hemolysin genes, and the ica operon. The S. haemolyticus strain was identified as ST-42/mecA-positive and harbored hemolysin genes. Linezolid resistance in S. aureus strain was associated with the mutations in the ribosomal proteins L3 and L4, and in S. haemolyticus, resistance was associated with the presence of cfr gene. Moreover, S. aureus strain harbored optrA and poxtA genes. We identified the first case of staphylococci carrying linezolid resistance genes from patients with chronic sinusitis in Poland. Since both S. aureus and CoNS are the most common etiological factors in laryngological infections, monitoring of such infections combined with surveillance and infection prevention programs is important to decrease the number of linezolid-resistant staphylococcal strains.

Virulence Factors in Coagulase-Negative Staphylococci

Coagulase-negative staphylococci (CoNS) have emerged as major pathogens in healthcare-associated facilities, being S. epidermidis, S. haemolyticus and, more recently, S. lugdunensis, the most clinically relevant species. Despite being less virulent than the well-studied pathogen S. aureus, the number of CoNS strains sequenced is constantly increasing and, with that, the number of virulence factors identified in those strains. In this regard, biofilm formation is considered the most important. Besides virulence factors, the presence of several antibiotic-resistance genes identified in CoNS is worrisome and makes treatment very challenging. In this review, we analyzed the different aspects involved in CoNS virulence and their impact on health and food.