Coagulase-negative staphylococci: pathogenesis, occurrence of antibiotic resistance genes and in vitro effects of antimicrobial agents on biofilm-growing bacteria

Staphylococcus capitis: insights into epidemiology, virulence, and antimicrobial resistance of a clinically relevant bacterial species

SUMMARYStaphylococcus capitis is divided into two subspecies, S. capitis subsp. ureolyticus (renamed urealyticus in 1992; ATCC 49326) and S. capitis subsp. capitis (ATCC 27840), and fits with the archetype of clinically relevant coagulase-negative staphylococci (CoNS). S. capitis is a commensal bacterium of the skin in humans, which must be considered an opportunistic pathogen of interest particularly as soon as it is identified in a clinically relevant specimen from an immunocompromised patient. Several studies have highlighted the potential determinants underlying S. capitis pathogenicity, resistance profiles, and virulence factors. In addition, mobile genetic element acquisitions and mutations contribute to S. capitis genome adaptation to its environment. Over the past decades, antibiotic resistance has been identified for S. capitis in almost all the families of the currently available antibiotics and is related to the emergence of multidrug-resistant clones of high clinical significance. The present review summarizes the current knowledge concerning the taxonomic position of S. capitis among staphylococci, the involvement of this species in human colonization and diseases, the virulence factors supporting its pathogenicity, and the phenotypic and genomic antimicrobial resistance profiles of this species.

Pathogenic Potential of Turicella otitidis and Staphylococcus auricularis: A Case Report

Objective: Turicella otitidis and Staphylococcus auricularis have been considered normal aural flora. Their significance in active infection is controversial. We examined a series of patients presenting with acute and chronic otitis media whose ear canal culture isolated T. otitidis and S. auricularis and explored possible pathogenicity, associated factors, and outcomes. Methods: This is a retrospective chart review of patients who presented to a tertiary center outpatient clinic between 2017 and 2022 with otologic microscopic examination of active infection and ear canal culture isolating T. otitidis or S. auricularis only. Clinical course was collected including history, microscopic otoscopy findings, interventions given, outcomes, and sensitivity results. Results: A total of 13 patients (10 with T. otitidis and 3 with S. auricularis) were included. Majority of the patients had a history of otologic surgery (92%) and tympanic membrane perforation (62%). All were treated with combinations of antibiotic otic drops (ie, fluoroquinolone, sulfa, or aminoglycoside based) ± oral antibiotics (ie, penicillin or trimethoprim/sulfamethoxazole). Otorrhea resolved among majority of patients. Otorrhea and mucosalization returned or continued among 4 patients. Sensitivity results demonstrated that 2 of 3 strains of T. otitidis were resistant to clindamycin. There was no resistance against S. auricularis for tested antibiotics. Conclusions: Our findings suggest the potential pathogenicity of T. otitidis and S. auricularis, especially among patients with prior ear surgery and tympanic membrane perforation. Violation of the epithelial barrier from surgery or trauma may contribute to their pathogenicity. Future study is warranted to elucidate pathogenicity of normal aural flora and its mechanisms.

Dynamics of antimicrobial resistance and virulence of staphylococcal species isolated from foods traded in the Cape Coast metropolitan and Elmina municipality of Ghana

The impact of staphylococci on food poisoning and infections could be higher than previously reported. In this study, we characterised the occurrence and coexistence of antimicrobial resistance and virulence genes of staphylococci isolates in foods. Staphylococci were isolated from 236 samples of selected street-vended foods and identified. The pattern of antimicrobial resistance and virulence genes in the staphylococci were assessed using disc diffusion, PCR and analysis of next-generation sequencing data. The food samples (70.76 %) showed a high prevalence of staphylococci and differed among the food categories. Forty-five Staphylococcus species were identified and comprised coagulase-negative and positive species. Staphylococcus sciuri (now Mammaliicoccus sciuri), S. aureus, S. kloosii, S. xylosus, S. saprophyticus, S. haemolyticus and S. succinus were the most abundant species. The staphylococcal isolates exhibited resistance to tetracycline, levofloxacin, ciprofloxacin, norfloxacin, gentamicin and amikacin and susceptibility to nitrofurantoin. Antimicrobial susceptibilities were also reported for cefoperazone, ceftriaxone, cefotaxime, nalidixic acid and piperacillin-tazobactam. The antimicrobial resistance and virulence genes commonly detected consisted of tet, arl, macB, van, gyr, nor, optrA, bcrA, blaZ, taeA and S. aureus lmrS. The isolates frequently exhibited multiple resistance (30.42 %) of up to eight antimicrobial drug classes. The isolates predominantly harboured genes that express efflux pump proteins (50.53 %) for antibiotic resistance compared with inactivation (10.05 %), target alteration (26.72 %), protection (7.67 %) and replacement (3.17 %). The virulence determinants comprised genes of pyrogenic toxin superantigens (eta, etb, tst), adhesions (clf, fnbA, fnbB, cna, map, ebp, spA, vWbp, coa) and genes that express exoproteins (nuclease, metalloprotease, γ-hemolysin, hyaluronate lyase). There was a statistically significant difference in the prevalence of staphylococci isolates and their antimicrobial resistance and virulence profile as revealed by the phenotypic, PCR and next-generation sequencing techniques. The findings suggest a higher health risk for consumers. We recommend a critical need for awareness and antimicrobial susceptibility and anti-virulence strategies to ensure food safety and counteract the spread of this clinically relevant genus.

Scalp microbiome of healthy women wearing hijab compared to those not wearing hijab: a cross-sectional study

Use of hijab can influence the scalp's condition, including its microbiome. To date there has been no study comparing scalp microbiome in women wearing hijab to that in women not wearing hijab. This was a cross-sectional study conducted from August 2019 to April 2021. Healthy women aged 18 years old or older who had not undergone menopause were recruited. Those in the hijab group should wear hijab minimum 8 h a day for at least 5 years. After wash-out period, the sample was collected from the subject's scalp. Next Generation Sequencing (NGS) was performed with primer V3-V4 region of 16S rRNA and ITS1 DNA for bacteria and fungi, respectively. Alpha diversity and beta diversity were identified, along with functional analysis. Actinobacteria and Ascomycota were the most dominant phyla on the scalp. S. capitis was more prominent in the hijab group while S. cohnii was more prominent in non-hijab group. Additionally, M. restricta was more common in hijab group while M. globosa was more common in non-hijab group. This study emphasizes the difference of scalp microbiome in women wearing hijab compared to women not wearing hijab, which indicated that women wearing hijab are more prone to seborrheic dermatitis.

Staphylococcus capitis: Review of Its Role in Infections and Outbreaks

In June 2021, a national incident team was formed due to an increased detection of Staphylococcus capitis in samples from hospitalised infants. Staphylococcus capitis has been known to cause outbreaks in neonatal units across the globe, but the extent of the UK spread was unclear. A literature review was undertaken to support case identification, clinical management and environmental infection control. A literature search was undertaken on multiple databases from inception to 24 May 2021, using keywords such as “Staphylococcus capitis”, “NRCS-A”, “S. capitis”, “neonate”, “newborn” and “neonatal intensive care unit” (NICU). After screening, 223 articles of relevance were included. Results show incidences of S. capitis outbreaks have frequently been associated with the outbreak clone (NRCS-A) and environmental sources. The NRCS-A harbours a multidrug resistance profile that includes resistance to beta-lactam antibiotics and aminoglycosides, with several papers noting resistance or heteroresistance to vancomycin. The NRCS-A clone also harbours a novel SCCmec-SCCcad/ars/cop composite island and increased vancomycin resistance. The S. capitis NRCS-A clone has been detected for decades, but the reasons for the potentially increased frequency are unclear, as are the most effective interventions to manage outbreaks associated with this clone. This supports the need for improvements in environmental control and decontamination strategies to prevent transmission.

Monitoring the effect of environmental conditions on safety of fresh produce sold in Qatar's wholesale market

Fresh produce imported by Qatar are mostly sold at the wholesale produce market (WPM) located in open-air and near major animal markets and slaughterhouses. This study was the first in Qatar to monitor the effect of environmental conditions on the microbial quality and safety of fresh produce sold at the WPM over 1 year. The monitoring involved the collection of 540 produce samples along with samples of air, soil, and surface swabs. Samples were analyzed for total aerobic bacteria (TAB); generic Listeria spp., Staphylococcus spp., Salmonella spp.; total coliforms and total fungi. Bacterial and fungal isolates were identified using 16S rRNA/ITS rRNA markers. Environmental/sanitary factors significantly impacted the prevalence of microorganisms in all samples tested. Produce quality was rated 'poor' during the months of November-February or May-August, with TAB and coliform counts exceeding 6 and 4 log₁₀ CFU/g, respectively. Bacillus subtilus, Enterobacter cloacae, E. faecium, P. expansium, P. aurantiocandidum, and A. niger were the most abundant species with prevalence rate of 11-30%. The high microbial load of environmental samples indicates that the location of the WPM near livestock markets is likely impacting the microbial quality of fresh produce. Therefore, effective control measures need to be implemented at WPM to improve produce safety yearlong.

Characterization of a Lytic Bacteriophage vB_SurP-PSU3 Infecting Staphylococcus ureilyticus and Its Efficacy Against Biofilm

In response to the increasing nosocomial infections caused by antimicrobial-resistant coagulase-negative staphylococci (CoNS), bacteriophages (phages) have emerged as an alternative to antibiotics. Staphylococcus ureilyticus, one of the representative species of the CoNS, is now considered a notable pathogen that causes nosocomial bloodstream infections, and its biofilm-forming ability increases pathogenicity and resistance to antimicrobial agents. In this study, a lytic phage infecting S. ureilyticus was newly isolated from wastewater collected from a sewage treatment plant and its biological and antimicrobial characteristics are described. The isolated phage, named vB_SurP-PSU3, was morphologically similar to Podoviridae and could simultaneously lyse some S. warneri strains used in this study. The sequenced genome of the phage consisted of linear dsDNA with 18,146 bp and genome-based phylogeny revealed that vB_SurP-PSU3 belonged to the genus Andhravirus. Although its overall genomic arrangement and contents were similar to those of other members of the Andhravirus, the predicted endolysin of vB_SurP-PSU3 distinctly differed from the other members of the genus. The bacteriolytic activity of vB_SurP-PSU3 was evaluated using S. ureilyticus ATCC 49330, and the phage could efficiently inhibit the planktonic growth of the bacteria. Moreover, the anti-biofilm analysis showed that vB_SurP-PSU3 could prevent the formation of bacterial biofilm and degrade the mature biofilm in vitro. In an additional cytotoxicity assay of vB_SurP-PSU3, no significant adverse effects were observed on the tested cell. Based on these findings, the newly isolated phage vB_SurP-PSU3 could be classified as a new member of Andhravirus and could be considered an alternative potential biocontrol agent against S. ureilyticus infections and its biofilm.

Emerging vancomycin-non susceptible coagulase negative Staphylococci associated with skin and soft tissue infections

Backgrounds

Observable emergence of Vancomycin-Non susceptible Coagulase-negative Staphylococci (VNS-CoNS) associated with skin and soft tissue infections spreading among the urban and rural populace is gradually intensifying severe complications. The isolated VNS-CoNS were evaluated with Matrix-assisted Laser Desorption/ionization Time of Flight Mass Spectrometry (MALDI ToF MS) for species characterization and pan-antimicrobial resistance pattern.

Methods

Out of 256 clinical samples collected including pus, abscess, ear swabs, eye swabs, and aspirates, 91 CoNS isolates were biotyped and further characterized with MALDI-TOF MS. Staphylococci marker genes, Vancomycin susceptibility, and biofilm assays were performed.

Results

Of 91 CoNS isolates, S.cohnii (2.3%), S.condimentii (3.4%), S. saprophyticus (6.7%), and S.scuri (21.1%) were characterized with MALDI-TOF with significant detection rate (99.4%; CI 95, 0.775–0.997, positive predictive values, 90.2%) compared to lower biotyping detection rate (p = 0.001). Hemolytic VNS-CoNS lacked nuc, pvl and spa genes from wound, ear, and aspirates of more 0.83 MARI clustered into a separate phylo-diverse group and were widely distributed in urban and peri-urban locations. MALDI TOF–MS yielded a high discriminatory potential of AUC-ROC score of 0.963 with true-positivity prediction. VNS-CoNS of MIC ≥ 16 µg/mL were observed among all the ages with significant resistance at 25th and 75th quartiles. More than 10.5% of CoNS expressed multi-antibiotic resistance with more than 8 µg/mL vancomycin cut-off values (p < 0.05).

Conclusion

Antibiotic resistant CoNS should be considered significant pathogens rather than contaminant. Biofilm producing VNS-S. sciuri and S. condimentii are potential strains with high pathological tropism for skin, soft tissues and wound infections, and these strains require urgent surveillance in peri-urban and rural communities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-022-00516-4.

Immunoinformatics and Biophysics Approaches to Design a Novel Multi-Epitopes Vaccine Design against Staphylococcus auricularis

Due to the misuse of antibiotics in our daily lives, antimicrobial resistance (AMR) has become a major health problem. Penicillin, the first antibiotic, was used in the 1930s and led to the emergence of AMR. Due to alterations in the microbe’s genome and the evolution of new resistance mechanisms, antibiotics are losing efficacy against microbes. There are high rates of mortality and morbidity due to antibiotic resistance, so addressing this major health issue requires new approaches. Staphylococcus auricularis is a Gram-positive cocci and is capable of causing opportunistic infections and sepsis. S. auricularis is resistant to several antibiotics and does not currently have a licensed vaccine. In this study, we used bacterial pan-genome analysis (BPGA) to study S. auricularis pan-genome and applied a reverse immunology approach to prioritize vaccine targets against S. auricularis. A total of 15,444 core proteins were identified by BPGA analysis, which were then used to identify good vaccine candidates considering potential vaccine filters. Two vaccine candidates were evaluated for epitope prediction including the superoxide dismutase and gamma-glutamyl transferase protein. The epitope prediction phase involved the prediction of a variety of B-Cell and T-cell epitopes, and the epitopes that met certain criteria, such as antigenicity, immunogenicity, non-allergenicity, and non-toxicity were chosen. A multi-epitopes vaccine construct was then constructed from all the predicted epitopes, and a cholera toxin B-subunit adjuvant was also added to increase vaccine antigenicity. Three-dimensional models of the vaccine were used for downward analyses. Using the best-modeled structure, binding potency was tested with MHC-I, MHC-II and TLR-4 immune cells receptors, proving that the vaccine binds strongly with the receptors. Further, molecular dynamics simulations interpreted strong intermolecular binding between the vaccine and receptors and confirmed the vaccine epitopes exposed to the host immune system. The results support that the vaccine candidate may be capable of eliciting a protective immune response against S. auricularis and may be a promising candidate for experimental in vitro and in vivo studies.

Predictive Factors, Treatment, and Outcomes of Coagulase-Negative Staphylococcal Peritonitis in Malaysian Peritoneal Dialysis Patients: A Single-Center Study

Aims

Coagulase-negative Staphylococci (CoNS) are frequently isolated in peritoneal dialysis (PD)-related peritonitis with a high rate of relapse and repeat peritonitis after initial response to antimicrobials. The optimal treatment regimen for CoNS peritonitis remains debatable. Hence, this study aimed to describe the clinical and microbiologic characteristics of CoNS peritonitis in a PD center and determine predictive factors influencing the outcomes.

Methods

All cases of CoNS peritonitis in Selayang Hospital between 2011 and 2019 were reviewed retrospectively.

Results

A total of 906 episodes of peritonitis were recorded; 140 episodes (15%) in 98 patients were caused by CoNS. The oxacillin and gentamicin resistance rates were 47% and 46%, respectively. The overall primary response rate was 90%, and the complete cure rate was 79%. Patients with concomitant exit-site infection (odds ratio (OR) 0.06, 95% confidence interval (CI) 0.01 to 0.40, P < 0.01) and history of recent systemic antibiotic use (OR 0.04, 95% CI 0.01 to 0.82, P=0.04) were less likely to achieve primary response. CoNS episodes that were treated with beta-lactam-based or vancomycin-based therapy had a similar primary response rate and complete cure rate. The rates of relapse and repeat were 12% and 16%, respectively. Relapsed episodes (OR 0.35, 95% CI 0.13 to 0.97, P=0.04) had a significantly lower complete cure rate than the first episodes.

Conclusion

Relapsed CoNS peritonitis was common and was associated with worse outcomes than the first episode of CoNS peritonitis. Oxacillin resistance was common, but the treatment outcome remained favourable when a beta-lactam-based regimen was used as empirical therapy.

Distribution and antibiotic-resistance of different Staphylococcus species identified by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) isolated from the oral cavity

Background: The use of antibiotics in dentistry is associated with the emergence and spread of antibiotic-resistant microorganisms, including commensal staphylococci.

Methods: A total of 367 oral samples were collected, from which staphylococci were isolated and identified by using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF). The antibiotic susceptibility of the isolates was determined and molecular characteristics for methicillin-resistant staphylococci was performed.

Results: A total of 103 coagulase-negative staphylococci (CoNS), among them S. warneri, S. haemolyticus, S. saprophyticus, S. pasteuri, S. epidermidis, S. hominis, S. xylosus, S. equorum, S. kloosii, S. succinus, S. cohnii, and S. simulans, were confirmed by MALDI-TOF. Resistance to most tested antibiotics was statistically higher in CoNS than in S. aureus isolates (P-value < 0.05). CoNS isolates showed high resistance to penicillin (S. saprophyticus 88.9%), erythromycin (S. haemolyticus 84.6%), fusidic acid (S. saprophyticus 77.8%), co-trimoxazole (S. epidermidis 71.4%), gentamicin (S. warneri 63.8%), and tetracycline (S. saprophyticus 55.6%). Multidrug resistance was largely observed, especially among S. haemolyticus and S. saprophyticus species. Methicillin-resistance in S. haemolyticus (38.5%), S. saprophyticus (22.2%) and S. aureus (13.5%) was associated with the presence of the mecA gene and SCCmec type IV or V.

Conclusion: Coagulase-negative staphylococci, especially S. haemolyticus and S. saprophyticus, seem to be a reservoir of methicillin resistance and multidrug resistance in the oral cavity.

Comparative Genomics Suggests a Taxonomic Revision of the Staphylococcus cohnii Species Complex

Staphylococcus cohnii (SC), a coagulase-negative bacterium, was first isolated in 1975 from human skin. Early phenotypic analyses led to the delineation of two subspecies (subsp.), Staphylococcus cohnii subsp. cohnii (SCC) and Staphylococcus cohnii subsp. urealyticus (SCU). SCC was considered to be specific to humans, whereas SCU apparently demonstrated a wider host range, from lower primates to humans. The type strains ATCC 29974 and ATCC 49330 have been designated for SCC and SCU, respectively. Comparative analysis of 66 complete genome sequences-including a novel SC isolate-revealed unexpected patterns within the SC complex, both in terms of genomic sequence identity and gene content, highlighting the presence of 3 phylogenetically distinct groups. Based on our observations, and on the current guidelines for taxonomic classification for bacterial species, we propose a revision of the SC species complex. We suggest that SCC and SCU should be regarded as two distinct species: SC and SU (Staphylococcus urealyticus), and that two distinct subspecies, SCC and SCB (SC subsp. barensis, represented by the novel strain isolated in Bari) should be recognized within SC. Furthermore, since large-scale comparative genomics studies recurrently suggest inconsistencies or conflicts in taxonomic assignments of bacterial species, we believe that the approach proposed here might be considered for more general application.

Short communication: Effects of moringa extract on adhesion and invasion of Escherichia coli O55 in bovine mammary epithelial cells

The objective of this study was to evaluate the antibacterial activities of extract derived from moringa leaves. In particular, the effect of moringa extract (Mor) on adhesion and invasion of Escherichia coli O55, Enterococcus faecalis, Staphylococcus simulans, and Serratia liquefaciens was evaluated in bovine mammary epithelial cells (MAC-T). Broth microdilution method, minimum inhibitory concentration and minimum bactericidal concentration assays, adhesion and invasion assays, and real-time PCR were performed. The minimum inhibitory concentration and minimum bactericidal concentration of Mor ranged from 12.5 to 50 mg/mL on 18 out of 27 tested isolates. Treatment of E. coli O55 with Mor (100 and 200 μg/mL) inhibited the adhesion and invasion on MAC-T cells via downregulation of adhesion factors (i.e., papC, f17c-A, and eaeA). Also, when MAC-T cells were pretreated with Mor (200 μg/mL, 12 h) and incubated with E. coli O55, Enterococcus faecalis, Staphylococcus simulans, or Serratia liquefaciens, both E. coli O55 and Enterococcus faecalis showed a significant decrease in adhesion and invasion. Staphylococcus simulans exhibited decreased adhesion and increased invasion. Serratia liquefaciens showed increased adhesion and decreased invasion. In addition, Mor increased mRNA expression of antioxidant enzymes (e.g., heme oxygenase-1, NAD(P)H:quinone oxidoreductase-1, and thioredoxin reductase 1) in MAC-T cells. In conclusion, 12.5 to 50 mg/mL of Mor exhibited antibacterial activity against 18 out of 27 tested isolates. Also, pretreatment of 200 μg/mL of Mor to MAC-T cells modulated adhesion and invasion of E. coli O55 and other mastitis-associated pathogens. Furthermore, Mor increased antioxidant capacities in MAC-T cells, but further in vivo studies are needed.

Antimicrobial Resistance Profiling of Coagulase-Negative Staphylococci in a Referral Center in South Italy: A Surveillance Study

Background:

CoNS are part of the normal flora of the skin, upper respiratory tract and human intestine. CoNS are able to colonize host tissues or inert materials such as prosthetics, heart valves, pacemakers, and urinary and venous catheters. They can also internalize in host cells, thus eluding immune defenses and attack by antibiotics.

Objective:

In this study, we collected the epidemiological data and determined the antibiotic susceptibility of 828 CoNS, collected in Garibaldi Hospital (Catania, Italy) between January 2016 and October 2018.

Methods:

Strains were evaluated by determining the Minimum Inhibitory Concentration (MIC) using the broth microdilution method, according to the guidelines of the Clinical and Laboratory Standards Institute. The antibiotic sensitivity pattern of CoNS against eighteen antibiotics was determined.

Results:

For all the 828 clinical isolates, varying resistance rates were observed: ampicillin (87%), penicillin (86%), amoxicillin-clavulanate (71%), oxacillin (70%), erythromycin (69%), azithromycin (68%), levofloxacin (55%), ciprofloxacin (54%), gentamycin (47%), moxifloxacin (42%), trimethoprim-sulfamethoxazole (30%), clindamycin (28%), tetracycline (24%), rifampicin (20%), quinupristin-dalfopristin (synercid) (4%). No strains investigated demonstrated resistance to teicoplanin, vancomycin and linezolid.

Conclusion:

Our results highlight the importance of monitoring the evolution of CoNS resistance in order to implement control measures and reduce the risk of spread in the population.

Virulence Characteristics of mecA-Positive Multidrug-Resistant Clinical Coagulase-Negative Staphylococci

Coagulase-negative staphylococci (CoNS) are an important group of opportunistic pathogenic microorganisms that cause infections in hospital settings and are generally resistant to many antimicrobial agents. We report on phenotypic and genotypic virulence characteristics of a select group of clinical, mecA-positive (encoding penicillin-binding protein 2a) CoNS isolates. All CoNS were resistant to two or more antimicrobials with S. epidermidis strain 214EP, showing resistance to fifteen of the sixteen antimicrobial agents tested. Aminoglycoside-resistance genes were the ones most commonly detected. The presence of megaplasmids containing both horizontal gene transfer and antimicrobial resistance genetic determinants indicates that CoNS may disseminate antibiotic resistance to other bacteria. Staphylococcus sciuri species produced six virulence enzymes, including a DNase, gelatinase, lipase, phosphatase, and protease that are suspected to degrade tissues into nutrients for bacterial growth and contribute to the pathogenicity of CoNS. The PCR assay for the detection of biofilm-associated genes found the eno (encoding laminin-binding protein) gene in all isolates. Measurement of their biofilm-forming ability and Spearman’s rank correlation coefficient analyses revealed that the results of crystal violet (CV) and extracellular polymeric substances (EPS) assays were significantly correlated (ρ = 0.9153, P = 3.612e-12). The presence of virulence factors, biofilm-formation capability, extracellular enzymes, multidrug resistance, and gene transfer markers in mecA-positive CoNS clinical strains used in this study makes them powerful opportunistic pathogens. The study also warrants a careful evaluation of nosocomial infections caused by CoNS and may be useful in studying the mechanism of virulence and factors associated with their pathogenicity in vivo and developing effective strategies for mitigation.

Distribution and antimicrobial resistance profile of coagulase-negative staphylococci from cattle, equipment, and personnel on dairy farm and abattoir settings

BACKGROUND

Safe food is central to social wellbeing. Coagulase-negative staphylococci (CNS) are a threat to food safety because they may harbor multiple enterotoxins and antimicrobial resistance (AMR) genes. CNS bacteria are an emerging nosocomial pathogen in public health. CNS also cause bovine mastitis with a significant economic loss in the dairy industry and may introduce toxins to the food supply chain resulting in foodborne illnesses. However, information on CNS and their AMR status are scarce in food animal production and processing lines in Ethiopia.

METHODOLOGY

This cross-sectional study evaluated the prevalence and AMR patterns of CNS in dairy farms and abattoirs using samples (n = 1001) from udder milk, beef carcass, personnel, and different abattoir and dairy equipment across five locations of central Oromia. The CNS isolates were identified via standard microbiological protocols and evaluated using disc diffusion test against 14 antimicrobials belonging to nine different broad classes. Uni-and-multivariable logistic regressions were used to analyze the association between potential risk factors (location, sample source, and sample type) and positivity to CNS.

RESULTS

The overall prevalence of CNS in the five different geographic locations studied was 9.6% (range: 6.7-12.4%) and varied between abattoirs (11.3%) and dairy farms (8.0%). CNS were prevalent on the carcass, milk, equipment, personnel hands, and nasal samples. Of all CNS isolates, 7.1, 10.7, 7.1, 12.5, 17.9, 10.7, 12.5, 7.1, 1.8, 5.4, 1.8, and 5.4% exhibited AMR simultaneously to single, double, 3, 4, 5, 6, 7, 7, 8, 9, 10, 11, and 13 antimicrobials, respectively. Overall, the isolates displayed 51 different AMR phenotypic patterns in which 50% of the isolates exhibited quadruple-resistance simultaneously based on the nine broad antimicrobial classes tested using 14 representative antimicrobials. The prevalence of multidrug-resistant (MDR) CNS (i.e. ≥ 3 classes of antimicrobials) was significantly (p = 0.037) different between locations with 100, 57.1, 50, 86.7, and 76.9% in Addis Ababa, Adama, Assela, Bishoftu, and Holeta, respectively. However, the prevalence of MDR CNS was not significantly (p = 0.20) different between dairy farms (87.5%) and abattoirs (71.9%). We evaluated the effect of acquiring cefoxitin-resistance of the isolates on the efficacy (i.e. inhibition zone) of the rest antimicrobials using General Linear Model after adjusting geographical locations as a random effect. Isolates with cefoxitin-resistance significantly displayed resistance to eight antimicrobials of 14 tested including amoxicillin, penicillin, cloxacillin, chloramphenicol, nalidixic acid, nitrofurantoin, and tetracycline (p = 0.000), and erythromycin (p = 0.02). On the other hand, cefoxitin-resistant isolates were susceptible to gentamicin, ciprofloxacin, kanamycin, streptomycin, and sulphamethoxazone trimethoprim (p = 0.000). Thus, antimicrobials such as gentamicin and ciprofloxacin may be an alternative therapy to treat cefoxitin-resistant CNS, as 96.4% of CNS isolates were susceptible to these antimicrobials. Overall, 94.1 and 54.5% of the CNS isolates among cefoxitin-resistant and cefoxitin-susceptible, respectively, harbored resistance to 3 or more classes of antimicrobials i.e. MDR.

CONCLUSION

The overall prevalence of CNS in milk, meat, equipment, and food handlers in central Oromia was 9.6% but varied by location and sample source. Some specific niches such as equipment, hands, and nasal cavities of personnel are significant sites for the source of CNS. Most, but not all, MDR CNS isolates were cefoxitin-resistant. Overall, 78.6% of the CNS tested were MDR and 50% had resistance to four or more broad classes of antimicrobials. CNS in food animals (raw milk and meat), equipment, and food handlers can be the source of MDR to the public. Personnel safety and hygienic food handling practices are needed. In addition, further investigation into the risk factors for the transmission and mechanisms of resistance of the CNS is required for intervention.

Oxytropis glabra DC. Inhibits Biofilm Formation of Staphylococcus epidermidis by Down-Regulating ica Operon Expression

Staphylococcus epidermidis is one of the main causes of medical device-related infections and bovine mastitis owing to its biofilm-forming abilities. Oxytropis glabra DC. is one of the most widespread Fabaceae species and used as a Chinese herbal formulation in Western China. Our research investigated the effects of O. glabra on the biofilm formation of S. epidermidis and the possible inhibiting mechanism. The biofilm-forming reference strain, S. epidermidis SE-1 (ATCC 35,984), was employed as a model and semi-quantitative biofilm assay was performed to evaluate the antibiofilm activity of O. glabra. The exopolysaccharides (EPS) production and expression of ica operon were studied to explore the possible antibiofilm mechanism using thin-layer chromatography and quantitative real-time PCR assay, respectively. The results obtained indicated that O. glabra decoction at 7.5 mg mL^-1 significantly inhibited biofilm formation by about 95% without affecting cell growth of S. epidermidis. Two hydrolysis productions of EPS were significantly decreased by 64% and 54% with the addition of 7.5 mg mL^-1O. glabra and the expression of icaR was significantly up-regulated 2.2-times, whereas icaB was significantly down-regulated more than 50% by 7.5 mg mL^-1O. glabra. These findings suggest a potential application for O. glabra as a promising candidate for the exploration of new drugs against S. epidermidis biofilm-associated infections.

In vitro activity and In vivo efficacy of Isoliquiritigenin against Staphylococcus xylosus ATCC 700404 by IGPD target

Staphylococcus xylosus (S. xylosus) is a type of coagulase-negative Staphylococcus, which was previously considered as non-pathogenic. However, recent studies have linked it with cases of mastitis in cows. Isoliquiritigenin (ISL) is a bioactive compound with pharmacological functions including antibacterial activity. In this study, we evaluated the effect of ISL on S. xylosus in vitro and in vivo. The MIC of ISL against S. xylosus was 80 μg/mL. It was observed that sub-MICs of ISL (1/2MIC, 1/4MIC, 1/8MIC) significantly inhibited the formation of S. xylosus biofilm in vitro. Previous studies have observed that inhibiting imidazole glycerol phosphate dehydratase (IGPD) concomitantly inhibited biofilm formation in S. xylosus. So, we designed experiments to target the formation of IGPD or inhibits its activities in S. xylosus ATCC 700404. The results indicated that the activity of IGPD and its histidine content decreased significantly under 1/2 MIC (40 μg/mL) ISL, and the expression of IGPD gene (hisB) and IGPD protein was significantly down-regulated. Furthermore, Bio-layer interferometry experiments showed that ISL directly interacted with IGPD protein (with strong affinity; KD = 234 μM). In addition, molecular docking was used to predict the binding mode of ISL and IGPD. In vivo tests revealed that, ISL significantly reduced TNF-α and IL-6 levels, mitigated the destruction of the mammary glands and reversed the production of inflammatory cells in mice. The results of the study suggest that, ISL may inhibit S. xylosus growth by acting on IGPD, which can be used as a target protein to treat infections caused by S. xylosus.

Pathogenic microbes contaminating mobile phones in hospital environment in Northeast India: incidence and antibiotic resistance

BACKGROUND

The present study attempts to identify and determine the pattern of drug susceptibility of the microorganisms present in mobile phones of health care workers (HCWs) and non-HCWs in a hospital environment. Mobile phones of 100 participants including both genders were randomly swabbed from nine different wards/units and the bacterial cultures were characterized using VITEK 2 system.

RESULTS

Forty-seven mobile phones were culture positive and a total of 57 isolates were obtained which consisted of 28 Gram-positive organisms and 29 Gram-negative organisms. The predominating organisms were Acinetobacter baumannii and Staphylococcus hominis. Among all the isolates from the mobile phones of HCW and non-HCWs, five isolates had ESBL and three isolates had colistin resistance. Incidentally, MRSA was not found on the mobile phones tested. The isolated organisms showed 100% susceptibility to linezolid, daptomycin, vancomycin, imipenem, meropenem, gentamicin, amikacin, ciprofloxacin and tigecycline, while high resistance was shown against benzylpenicillin (75.0%), cefuroxime and cefuroxime axetil (56.5%). Non-HCWs' mobile phones were more contaminated as compared to HCWs (P = 0.001) and irrespective of individuals' gender or toilet habits, both Gram-positive and Gram-negative organisms were present on the mobile phones.

CONCLUSION

This study reports for the first time that the mobile phones of non-health care workers harbour more bacterial diversity and are more prone to cause transmission of pathogens. This study can serve to educate the public on personal hand hygiene practices and on maintaining clean mobile phones through antiseptic measures.

Suppressing Antibacterial Resistance: Chemical Binding of Monolayer Quaternary Ammonium Salts to Polymethyl Methacrylate in an Aqueous Solution and its Clinical Efficacy

Antibacterial resistance (ABR) poses an enormous threat to human health. ABR mainly develops due to bacteria being constantly exposed to diluted levels of disinfectants. Here, we propose a method for suppressing ABR through the chemical binding of disinfectants to polymethyl methacrylate (PMMA) device surfaces in solutions of 5%, 10%, and 20% disinfectant concentrations. PMMA discs were fabricated from a commercial orthodontic acrylic resin system (Ortho-Jet) and quaternary ammonium salts (QAS), 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride (42% in methanol), were used as the disinfectant. The PMMA surfaces were activated in 3 M sulfuric acid at 80 °C for 5 h for the esterification of hydrolyzed QAS to PMMA. Fourier transform infrared difference spectra confirmed that the carboxy-terminated PMMA was chemically bound to the QAS. In vitro cell viability tests using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assays revealed that 5%QAS-c-PMMA was more biocompatible than 10%QAS-c-PMMA and 20%QAS-c-PMMA. The results of antibacterial tests and clinical trials demonstrated the excellent antibacterial power of 5%QAS-c-PMMA. This method is the first solution-based approach to successfully avoid disinfectant leakage and subsequent ABR, as revealed by mass spectrometry studies of the solution obtained by agitating the disinfectant-bound PMMA for 28 days.

Frequency of icaA and icaD determinants and biofilm formation among coagulase-negative staphylococci associated with nasal carriage in neonatal intensive care units

Introduction

Nasal colonization with coagulase-negative staphylococci (CoNS) may be a preliminary risk factor for systemic infection. The aim of this study was to assess the frequency of ica A and D genes and biofilm formation among hospital-acquired nasal colonizing CoNS strains isolated from neonates in the neonatal intensive care units (NICUs). Antibiotic sensitivity patterns and some relevant risk factors were estimated.

Methods

This study assessed nasal colonization with CoNS among neonates at days one and three of admission to NICUs of Beni-Suef University Hospital and Beni-Suef General Hospital from November 2015 to May 2016. The isolates were screened and identified; susceptibility testing was performed. Biofilm formation was examined using the Congo red agar method. Isolates identified as CoNS were tested by polymerase chain reaction (PCR) for the presence of mecA and icaA and icaD genes.

Results

A total of 340 nasal swabs were collected from 170 neonates. The incidence of nasal colonization with CoNS was 50%. The species most frequently isolated were S. haemolyticus and S. epidermidis. Multidrug resistance (MDR) was detected in 86% of isolates. It was found that there was a strong association between the presence of mecA gene and phenotypic resistance to methicillin and also the presence of the icaA gene and biofilm formation.

Conclusions

Neonates admitted to NICUs can become reservoirs for CoNS strains, leading to potential dissemination of MDR strains into the community.

Clonally Diverse Methicillin and Multidrug Resistant Coagulase Negative Staphylococci Are Ubiquitous and Pose Transfer Ability Between Pets and Their Owners

Sixty-eight owners and 66 pets, from 43 unrelated pet-owning households were screened for methicillin-resistant coagulase negative staphylococci (MRCoNS), potential cases of MRCoNS interspecies transmission (IT), and persistence. MRCoNS isolates were identified by microbiological and molecular tests. MLST-based phylogenetic analysis was performed in Staphylococcus epidermidis isolates. Antimicrobial susceptibility was evaluated using phenotypic and molecular methods. SCCmec type and the presence of biofilm-related ica locus was PCR-tested. Isolates suspected for MRCoNS IT cases were subjected to SmaI-PFGE analysis and individuals from positive households were followed-up for 1 year for carriage dynamics (every 3 months, T0-T4). Nineteen MRCoNS isolates from owners (27.9%) and 12 from pets (16.7%) were detected, coming from 20 households (46.5%). S. epidermidis was predominant (90 and 67% of human and animal strains, respectively), showing high phylogenetic diversity (16 STs among 24 strains). Methicillin-resistant S. epidermidis (MRSE) strains belonged to CC5 (75%), CC11 (12.5%), singleton S556 (8.3%), and S560 (4.17%). Significant host-associated differences were observed for resistance to aminoglycosides, co-trimoxazole, chloramphenicol (higher in animal isolates) and tetracycline (higher among human strains). Multidrug resistance (MDR) was common (68.4%) and associated with human strains. Great diversity of ccr and mec complexes were detected, most strains being non-typeable, followed by SCCmecIV and V. Over one third of isolates (most from owners), carried the ica locus, all MRSE CC5. Two sporadic IT cases (T0) were identified in owners and dogs from two households (4.7%), with diverse interspecies-exchanged clones detected along the sampling year, especially in dogs. A comparative analysis of all MRCoNS, with all nasal coagulase positive staphylococci (CoPS) recovered from the same individuals at T0, revealed that CoPS alone was predominant in owners and pets, followed by co-carriage of CoPS and MRCoNS in owners but single MRCoNS in pets. Statistical analyses revealed that owners are more prone to co-carriage and that co-existence of IT cases and co-carriage are positively interrelated. MRCoNS from healthy owners and their pets are genetically heterogeneous MDR strains that are spread in the community. Therefore, pets also contribute to the dissemination of successful human clones. Owner-pet inhabitancy increases the risk for staphylococcal temporal concomitance with its subsequent risk for bacterial infection and genetic exchange.

Biofilm formation by staphylococci in health-related environments and recent reports on their control using natural compounds

Staphylococci are Gram-positive bacteria that are ubiquitous in the environment and able to form biofilms on a range of surfaces. They have been associated with a range of human health issues such as medical device-related infection, localized skin infection, or direct infection caused by toxin production. The extracellular material produced by these bacteria resists antibiotics and host defence mechanism which complicates the treatment process. The commonly reported Staphylococcus species are Staphylococcus aureus and S. epidermidis as they inhabit human bodies. However, the emergence of other staphylococci, such as S. haemolyticus, S. lugdunensis, S. saprophyticus, S. capitis, S. saccharolyticus, S. warneri, S. cohnii, and S. hominis, is also of concern and they have been associated with biofilm formation. This review critically assesses recent cases on the biofilm formation by S. aureus, S. epidermidis, and other staphylococci reported in health-related environments. The control of biofilm formation by staphylococci using natural compounds is specifically discussed as they represent potential anti-biofilm agents which may reduce the burden of antibiotic resistance.

Staphylococcus caprae: A Skin Commensal with Pathogenic Potential

Staphylococcus caprae (S. caprae) is a catalase-positive, coagulase-negative organism that was first isolated from goat milk, and was later found to colonize healthy human skin, nails, and nasal mucosa. Rarely, this commensal organism can become pathogenic in humans. S. caprae has been implicated in a variety of human infections, with the highest incidence being in bone and joint infections. We describe a man who, after receiving facet joint injections for back pain, developed native vertebral discitis, vertebral osteomyelitis with phlegmon, and bilateral psoas abscesses, from which S. caprae was isolated.

Prevalence and antimicrobial resistance of coagulase negative staphylococci clinical isolates from Ethiopia: a meta-analysis

Background

Antimicrobial resistant Coagulase-negative Staphylococci (CoNS) have limited treatment options, rendered diseases untreatable and made hospitals to be reservoirs of the resistant strains. The aim of this study was to estimate the pooled prevalence and antimicrobial resistance of clinical isolates of CoNS from Ethiopia.

Results

The electronic database search yielded 6511 articles of which 21 met predefined inclusion criteria. The pooled prevalence of CoNS from Ethiopia was 12% (95% confidence interval (CI): 8, 16%). The analyses revealed high level of CoNS resistance to methicilin (37%[95% CI: 21, 55%]), vancomycin (911%[95% CI: 0, 35%]), penicillin (58%[95% CI: 42, 74%]), amoxicillin (42%[95% CI: 23, 61%]), amoxicillin-clavulanate (27%[95% CI: 2, 27%]), ampicillin (64%[95% CI: 46, 80%]), tetracycline (60% [95% CI: 49, 70%]), doxycycline (36%[95% CI:19,55%]), Sulfamethoxazole-trimethoprim (50%[95% CI: 36, 64%]), ceftriaxone (27% [95% CI: 18, 38%]), cephalothin (32% [95% CI: 7, 62%]), norfloxacin (39%[95% CI: 24, 56%]), chloramphenicol (40%[95% CI: 23, 58%]), clindamycin (11% [95% CI: 2, 27%]), ciprofloxacin (14%[95% CI: 6, 22%]), gentamicin (27%[95% CI:19,36%]) and erythromycin (30%[95% CI:20%,42%]). High heterogeneity, I² ranging from 69.04 to 96.88%; p-values ≤0.01, was observed. Eggers’ test did not detect publication bias for the meta-analyses and low risk of bias was observed in included studies.

Conclusions

CoNS has gotten resistant to commonly used antimicrobials from Ethiopia. There is a need of launching national antimicrobial treatment, development and implementation of policy guidelines to contain the threat. Further research focusing on factors promoting resistance and the effect of resistance on treatment outcome studies are warranted.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1188-6) contains supplementary material, which is available to authorized users.

Antibiotic sensitivities of coagulase-negative staphylococci and Staphylococcus aureus in hip and knee periprosthetic joint infections: does this differ if patients meet the International Consensus Meeting Criteria?

Introduction

Coagulase-negative staphylococci (CoNS) are the main pathogens responsible for prosthetic joint infections (PJIs). As normal inhabitants of human skin, it is often difficult to define if they are contaminants, or if they have an active role in initiating infection. This study aims to evaluate differences in CoNS organisms (Staphylococcus hominis, Staphylococcus capitis, Staphylococcus haemolyticus, Staphylococcus warneri) and Staphylococcus aureus in terms of isolation rate and antimicrobial susceptibility from patients who met the International Consensus Meeting (ICM) criteria for PJIs and those who did not.

Methods

Staphylococci isolates from January 2014 to December 2015 retrieved from patients undergoing revision joint arthroplasty were classified in accordance with criteria established by the ICM of Philadelphia.

Results

As per the consensus classification, 50 CoNS and 39 S. aureus infections were recognized as pathogens, while 16 CoNS and four S. aureus were considered as contaminants. Frequency of isolation of S. aureus was significantly higher in infected patients than in those without infection, while no significant differences were observed among CoNS. Resistance to levofloxacin, erythromycin, gentamicin trimethoprim/sulfamethoxazole, and rifampicin was significantly more frequent in S. haemolyticus than in the other species, as well as resistance to erythromycin and gentamicin in S. hominis. In comparison to S. aureus, CoNS were significantly more resistant to daptomycin and gentamicin and more susceptible to rifampicin.

Conclusion

CoNS, other than Staphylococcus epidermidis, are frequently isolated from PJIs, and their infective role and antimicrobial susceptibility need to be assessed on an individual patient basis. S. haemolyticus seems to emerge as responsible for PJI in a large volume of patients, and its role needs to be further investigated, also considering its pattern of resistance.

Routine cultures for seemingly aseptic revision shoulder arthroplasty: are they necessary?

Propionibacterium acnes has recently gained attention as the leading cause of periprosthetic joint infections (PJIs) after shoulder arthroplasty. Unlike PJIs in the lower extremity, PJIs after shoulder arthroplasty usually have an indolent course and are notoriously difficult to diagnose. Most of the time, the diagnosis is made after positive intraoperative cultures are taken at the time of revision surgery. Adding even more complexity to the diagnosis is the high rate of P acnes-positive cultures taken at the time of primary shoulder surgery. In many cases the preoperative workup yields no suspicion for infection; however, intraoperative cultures are taken to completely eliminate the potential of an ongoing indolent infection. Concerns over how to interpret positive P acnes culture results and the high rate of culture positivity in primary shoulder arthroplasty, as well as the potentially high rate of contamination, have led surgeons to wonder about the utility of obtaining intraoperative cultures at the time of revision shoulder arthroplasty. We present evidence for and against the practice of obtaining routine intraoperative cultures at the time of seemingly aseptic revision shoulder arthroplasty.

Antibiotic resistance, ability to form biofilm and susceptibility to copper alloys of selected staphylococcal strains isolated from touch surfaces in Polish hospital wards

BACKGROUND

Despite the employment of sanitary regimes, contact transmission of the aetiological agents of hospital infections is still exceedingly common. The issue of microbe transmission becomes particularly important when facing multidrug-resistant microorganisms such as methicillin-resistant staphylococci. In the case of deficiencies in cleaning and disinfection procedures, hospital equipment made of copper alloys can play an important role, complementing traditional hospital hygiene procedures. The objective of this study was to characterize staphylococcal strains isolated from touch surfaces in Polish hospital wards in terms of their drug resistance, ability to form biofilm and susceptibility to antimicrobial activity of copper alloys.

METHODS

The materials for the study were 95 staphylococcal strains isolated from touch surfaces in 13 different hospital wards from Małopolska province (the south of Poland). Phenotypic and genotypic antibiotic resistance were checked for erythromycin, clindamycin, gentamycin, ciprofloxacin, trimethoprim/sulfamethoxazole and mupirocin. Biofilm formation ability for the tested strains was checked with the use of culture on Congo red agar. Susceptibility to copper, tin bronze, brass and new silver was tested using a modification of the Japanese standard.

RESULTS

Over 67% of the analysed staphylococcal strains were methicillin-resistant (MR). Four strains were resistant to all of the tested antibiotics, and 14 were resistant to all except mupirocin. Strains classified as MR had significantly increased resistance to the remaining antibiotic groups. About one-third of the analysed strains revealed biofilm-forming ability. Among the majority of species, biofilm-forming and non-biofilm-forming strains were distributed evenly; in the case of S. haemolyticus only, negative strains accounted for 92.8%. Susceptibility to copper alloys was different between strains and rather lower than in the case of the SA strain selected for comparison.

CONCLUSIONS

Coagulase-negative staphylococci, the most commonly isolated in Polish hospital wards, should not be neglected as an infection risk factor due their high antibiotic resistance. Our experiments confirmed that touch surfaces made of copper alloys may play an important role in eliminating bacteria from the hospital environment.