Antibiotics

2025

Jump to: 2024, 2023

37 pages, 1405 KiB

Open AccessReview

Staphylococcus aureus: A Review of the Pathogenesis and Virulence Mechanisms

by Rahima Touaitia, Assia Mairi, Nasir Adam Ibrahim, Nosiba S. Basher, Takfarinas Idres and Abdelaziz Touati

Antibiotics 2025, 14(5), 470; https://doi.org/10.3390/antibiotics14050470 - 6 May 2025

Viewed by 674

Abstract

Staphylococcus aureus is a formidable human pathogen responsible for infections ranging from superficial skin lesions to life-threatening systemic diseases. This review synthesizes current knowledge on its pathogenesis, emphasizing colonization dynamics, virulence mechanisms, biofilm formation, and antibiotic resistance. By analyzing studies from PubMed, Scopus, [...] Read more.

Staphylococcus aureus is a formidable human pathogen responsible for infections ranging from superficial skin lesions to life-threatening systemic diseases. This review synthesizes current knowledge on its pathogenesis, emphasizing colonization dynamics, virulence mechanisms, biofilm formation, and antibiotic resistance. By analyzing studies from PubMed, Scopus, and Web of Science, we highlight the pathogen’s adaptability, driven by surface adhesins (e.g., ClfB, SasG), secreted toxins (e.g., PVL, TSST-1), and metabolic flexibility in iron acquisition and amino acid utilization. Nasal, skin, and oropharyngeal colonization are reservoirs for invasive infections, with biofilm persistence and horizontal gene transfer exacerbating antimicrobial resistance, particularly in methicillin-resistant S. aureus (MRSA). The review underscores the clinical challenges of multidrug-resistant strains, including vancomycin resistance and decolonization strategies’ failure to target single anatomical sites. Key discussions address host–microbiome interactions, immune evasion tactics, and the limitations of current therapies. Future directions advocate for novel anti-virulence therapies, multi-epitope vaccines, and AI-driven diagnostics to combat evolving resistance. Strengthening global surveillance and interdisciplinary collaboration is critical to mitigating the public health burden of S. aureus. Full article

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16 pages, 1402 KiB

Open AccessArticle

Prevalence, Antimicrobial Resistance, and Virulence Potential of Staphylococcus aureus in Donkeys from Nigeria

by Onyinye Josephine Okorie-Kanu, Madubuike Umunna Anyanwu, Obichukwu Chisom Nwobi, Regina Yaya Tambe-Ebot, Nkechi Harriet Ikenna-Ezeh, Chukwuemeka Calistus Okolo, Lynda Onyinyechi Obodoechi, Patience Chinasa Ugwu, Ifeyinwa Riona Okosi, Ishmael Festus Jaja and James Wabwire Oguttu

Antibiotics 2025, 14(5), 453; https://doi.org/10.3390/antibiotics14050453 - 29 Apr 2025

Viewed by 319

Abstract

Background: Animal-associated antimicrobial-resistant staphylococci pose a One Health concern, as they can spread into the environment and cause serious infections. Yet, donkeys in Nigeria have been largely overlooked as potential reservoirs of these pathogens. Aim/Objectives: To isolate Staphylococcus aureus from donkeys in Obollo-Afor, [...] Read more.

Background: Animal-associated antimicrobial-resistant staphylococci pose a One Health concern, as they can spread into the environment and cause serious infections. Yet, donkeys in Nigeria have been largely overlooked as potential reservoirs of these pathogens. Aim/Objectives: To isolate Staphylococcus aureus from donkeys in Obollo-Afor, southeast Nigeria, assess their antimicrobial resistance profiles, and evaluate their virulence potential. Materials and Methods: Staphylococci were isolated from the nasal swabs of 250 donkeys, using mannitol salt agar, confirmed biochemically, with Staphylococcus aureus identified via a latex agglutination test and mass spectrometry. The resistance profiles of the isolates, including in regard to methicillin, inducible clindamycin, and β-lactamase production, were determined using disc diffusion, while vancomycin resistance was assessed through the use of agar dilution. The virulence factors were evaluated phenotypically. Results: Of the 250 samples, 11 (4.4%) contained S. aureus and 239 (95.6%) grew other Staphylococcus species. The resistance rates of the 11 S. aureus isolates to gentamicin, penicillin, tigecycline, cefoxitin, linezolid, and chloramphenicol were 45.5%, 66.7%, 54.5%, 27.3%, 36.4%, and 18.1%, respectively. The phenotypic methicillin-resistant S. aureus prevalence was 1.2%. Additionally, 23.5% of the S. aureus isolates were multidrug resistant, with a mean antibiotic resistance index of 0.25. All the S. aureus isolates exhibited virulence factors like clumping factor expression, catalase, caseinase, lecithinase, and gelatinase activity, while the occurrence of haemagglutinin, biofilm, pellicle, and hemolysin occurred in 27.3%, 54.5%, 36.4%, 72.2%, respectively. Conclusion: Although a small percentage of donkeys in Nigeria may harbor S. aureus, these animals are potentially spreading antimicrobial resistance, including multidrug and methicillin resistance, to humans and the environment. Full article

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14 pages, 4380 KiB

Open AccessArticle

Antimicrobial Activity of Pediococcus pentosaceus PMY2 Against Multidrug-Resistant Pathogens

by Gyeong-Seon Yi, Xiangji Jin, Qiwen Zheng, Trang Thi Minh Nguyen, Su-Jin Yang and Tae-Hoo Yi

Antibiotics 2025, 14(4), 389; https://doi.org/10.3390/antibiotics14040389 - 8 Apr 2025

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Abstract

Background/Objectives: Multidrug-resistant (MDR) pathogens pose a critical challenge in infection treatment. Pediococcus pentosaceus (P. pentosaceus) is known for its antimicrobial activity; however, studies on its effects against MDR pathogens remain limited. This study aimed to evaluate the antimicrobial and biological [...] Read more.

Background/Objectives: Multidrug-resistant (MDR) pathogens pose a critical challenge in infection treatment. Pediococcus pentosaceus (P. pentosaceus) is known for its antimicrobial activity; however, studies on its effects against MDR pathogens remain limited. This study aimed to evaluate the antimicrobial and biological activities of P. pentosaceus PMY2, isolated from fermented porcine colostrum yogurt, against MDR pathogens, including Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Escherichia coli (E. coli). Methods: The antimicrobial, anti-inflammatory, and cytotoxic effects of P. pentosaceus PMY2 were evaluated in vitro. In addition, IL-6 and TNF-α levels were analyzed using an ELISA kit. Results: The MIC value against S. aureus KCTC 3881 and MRSA (CCARM 3089) was 0.31 mg/mL, while the MBC values were 0.63 mg/mL and 2.5 mg/mL, respectively. At MIC, biofilm formation was inhibited by 62.2% in S. aureus KCTC 3881 and by 51.5% in MRSA. CFS exhibited low cytotoxicity in RAW 264.7 macrophages and significantly reduced NO production, IL-6, and TNF-α levels, indicating strong anti-inflammatory effects. Conclusions: These findings suggest that P. pentosaceus PMY2 exhibited excellent antimicrobial and anti-inflammatory activity against MDR pathogens, demonstrating its potential as a natural antimicrobial agent. These results indicate that PMY2 CFS could be a promising candidate for addressing antibiotic resistance issues. Full article

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30 pages, 4094 KiB

Open AccessReview

Lysyl-Phosphatidylglycerol: A Lipid Involved in the Resistance of Staphylococcus aureus to Antimicrobial Peptide Activity

by Andrea Vásquez, Chad Leidy and Marcela Manrique-Moreno

Antibiotics 2025, 14(4), 349; https://doi.org/10.3390/antibiotics14040349 - 28 Mar 2025

Viewed by 627

Abstract

Lysyl-phosphatidylglycerol (lysyl-PG) is one of the major lipids found in bacterial membranes; it is synthesized by attaching lysine to the headgroup of phosphatidylglycerol. First identified in Staphylococcus aureus in 1964, lysyl-PG is now recognized as a virulence factor that protects Staphylococcus aureus from [...] Read more.

Lysyl-phosphatidylglycerol (lysyl-PG) is one of the major lipids found in bacterial membranes; it is synthesized by attaching lysine to the headgroup of phosphatidylglycerol. First identified in Staphylococcus aureus in 1964, lysyl-PG is now recognized as a virulence factor that protects Staphylococcus aureus from antimicrobial agents, such as cationic antimicrobial peptides and phospholipase A2 type IIA. Under normal growth conditions, Staphylococcus aureus membranes are negatively charged due to a high proportion of anionic lipids, such as phosphatidylglycerol and cardiolipin. This intrinsic anionic charge helps attract positively charged antimicrobial agents to the membrane surface, increasing their disruptive activity. The presence of lysyl-PG reduces electrostatic interactions, making the membrane less susceptible to cationic agents. The biosynthesis of lysyl-PG is mediated by the multiple peptide resistance factor (MprF) enzyme, which catalyzes the modification of phosphatidylglycerol and translocation of lysyl-PG to the outer membrane in the presence of antimicrobial agents. However, several studies indicate that lysyl-PG not only responds to the presence of antimicrobial agents but can fluctuate based on environmental factors such as oxygen availability and nutrient composition. Acidic conditions and nutrient-rich media often result in increased lysyl-PG production, suggesting that bacterial membranes can be resistant to cationic antimicrobial agents even in their native state. Recent studies propose that targeting MprF to inhibit lysyl-PG biosynthesis could be a promising strategy to counter antimicrobial resistance. This review highlights the role of lysyl-PG in modulating membrane charge and its influence on antimicrobial agent efficacy and discusses a possible strategy for treatment by targeting lysyl-PG synthesis. Full article

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15 pages, 1998 KiB

Open AccessArticle

Efficacy of Three Kayviruses Against Staphylococcus aureus Strains Isolated from COVID-19 Patients

by Lidia Piechowicz, Katarzyna Kosznik-Kwaśnicka, Natalia Kaźmierczak, Milena Grzenkowicz, Małgorzata Stasiłojć, Agnieszka Necel, Olesia Werbowy and Anna Pałubicka

Antibiotics 2025, 14(3), 257; https://doi.org/10.3390/antibiotics14030257 - 3 Mar 2025

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Abstract

Background/Objectives: The viral pandemic caused by the SARS-CoV-2 virus has affected millions of people. However, it was noticed that high mortality was often a result of bacterial co-infections. One of the main pathogens responsible for secondary infections in patients with viral respiratory tract [...] Read more.

Background/Objectives: The viral pandemic caused by the SARS-CoV-2 virus has affected millions of people. However, it was noticed that high mortality was often a result of bacterial co-infections. One of the main pathogens responsible for secondary infections in patients with viral respiratory tract infections, including COVID-19, is Staphylococcus aureus. In recent years, the number of infections caused by drug-resistant strains of S. aureus has been growing rapidly, often exceeding the number of infections caused by antibiotic-sensitive strains. In addition, biofilm-related infections are more difficult to treat due to the lower sensitivity of biofilm structure to antibiotics. Bacteriophages are seen as alternative treatment of bacterial infections. Therefore, in our work, we have analyzed the efficacy of three Kayviruses against S. aureus strains isolated from COVID-19 patients. Methods: We analyzed the ability of tested phages to remove S. aureus biofilm both from polystyrene plates as well as from the surface of pulmonary epithelial cells. Results: We have observed that tested Kayviruses had a broad host range. Furthermore, phages were able to effectively reduce biofilm biomass and number of viable cells in pure culture. During our research, none of the tested phages was shown to have a negative effect on cell viability and were able to inhibit the negative effect S. aureus had on cell condition. Conclusions: Our results show tested phages were effective in reducing the biofilm of S. aureus strains isolated from COVID-19 patients, had no adverse effect on lung epithelial cell viability. Therefore, it should be recognized that the properties of three studied Kayviruses give them an advantage in the selection of phages for treatment of staphylococcal infections. Full article

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2024

Jump to: 2025, 2023

11 pages, 1687 KiB

Open AccessArticle

Comparative Analysis of Methicillin-Resistant Staphylococcus pseudintermedius Prevalence and Resistance Patterns in Canine and Feline Clinical Samples: Insights from a Three-Year Study in Germany

by Leonie Feuer, Stefanie Katharina Frenzer, Roswitha Merle, Wolfgang Bäumer, Antina Lübke-Becker, Babette Klein and Alexander Bartel

Antibiotics 2024, 13(7), 660; https://doi.org/10.3390/antibiotics13070660 - 17 Jul 2024

Cited by 4 | Viewed by 2560

Abstract

The emergence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) presents a significant public health concern globally, particularly within veterinary medicine. MRSP’s resistance to multiple antibiotics is limiting treatment options and potentially leading to severe infections in companion animals. This study aimed to understand antimicrobial resistance [...] Read more.

The emergence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) presents a significant public health concern globally, particularly within veterinary medicine. MRSP’s resistance to multiple antibiotics is limiting treatment options and potentially leading to severe infections in companion animals. This study aimed to understand antimicrobial resistance in dogs and cats, focusing on MRSP resistance patterns and its prevalence in Germany. We analyzed results of bacterial diagnostic samples from canines and felines, sourced from a German veterinary diagnostic microbiology laboratory between 2019 and 2021. This dataset included samples from 3491 veterinary practices, covering 33.1% of veterinary practices and clinics in Germany. MRSP rates were detailed by host species, sample types and co-resistance patterns. Analysis of 175,171 bacterial examination results revealed S. pseudintermedius in 44,880 samples, yielding a 25.6% isolation rate. S. pseudintermedius was more prevalent in dogs (35.0%) than cats (3.6%). Methicillin resistance was found in 7.5% of all S. pseudintermedius isolates. MRSP prevalence was higher in feline samples (16.1%, 95% CI 14.4–17.8) compared to canine samples (7.1%, 95% CI 6.8–7.0). S. pseudintermedius showed high resistance rates to ampicillin (cats: 48.6%, dogs: 67.6%) and clindamycin (cats: 37.2%, dogs: 32.7%), while MRSP exhibited high co-resistance to clindamycin (cats: 82.8%, dogs: 85.4%) and sulfamethoxazole + trimethoprim (cats: 66.4%, dogs: 66.2%). Our study revealed distinct resistance patterns of MRSP in cats compared to dogs, highlighting the need for tailored treatment approaches and the importance of antimicrobial resistance surveillance. Full article

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51 pages, 2147 KiB

Open AccessReview

Methicillin-Resistant Staphylococcus aureus (MRSA) in Dairy Products and Bulk-Tank Milk (BTM)

by Camino González-Machado, Rosa Capita and Carlos Alonso-Calleja

Antibiotics 2024, 13(7), 588; https://doi.org/10.3390/antibiotics13070588 - 25 Jun 2024

Cited by 3 | Viewed by 2804

Abstract

In order to contribute to an assessment of the role of food in the risks of transmission of methicillin-resistant Staphylococcus aureus (MRSA), a review was undertaken of research on this microorganism in milk and dairy products published from January 2001 to February 2024. [...] Read more.

In order to contribute to an assessment of the role of food in the risks of transmission of methicillin-resistant Staphylococcus aureus (MRSA), a review was undertaken of research on this microorganism in milk and dairy products published from January 2001 to February 2024. A total of 186 publications were selected, 125 for dairy products and 61 for bulk-tank milk (BTM). MRSA was detected in 68.8% of the research into dairy products and 73.8% of investigations relating to BTM, although in most studies the prevalence was less than 5%. Of the set of S. aureus strains isolated, approximately 30% corresponded to MRSA. The foods most extensively contaminated with this microorganism were raw milk and some types of soft cheese. Determination of the mecA gene on its own is known not to suffice for the detection of all MRSA strains. The great diversity of techniques used to study MRSA in milk and dairy products made it difficult to draw comparisons between studies. It would thus be advisable to develop a standardized protocol for the study of this microorganism in foods. Full article

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16 pages, 3595 KiB

Open AccessArticle

Characterisation of PVL-Positive Staphylococcus argenteus from the United Arab Emirates

by Stefan Monecke, Sindy Burgold-Voigt, Sascha D. Braun, Celia Diezel, Elisabeth M. Liebler-Tenorio, Elke Müller, Rania Nassar, Martin Reinicke, Annett Reissig, Abiola Senok and Ralf Ehricht

Antibiotics 2024, 13(5), 401; https://doi.org/10.3390/antibiotics13050401 - 27 Apr 2024

Cited by 3 | Viewed by 2332

Abstract

Staphylococcus argenteus is a recently described staphylococcal species that is related to Staphylococcus aureus but lacks the staphyloxanthin operon. It is able to acquire both resistance markers such as the SCCmec elements and mobile genetic elements carrying virulence-associated genes from S. aureus [...] Read more.

Staphylococcus argenteus is a recently described staphylococcal species that is related to Staphylococcus aureus but lacks the staphyloxanthin operon. It is able to acquire both resistance markers such as the SCCmec elements and mobile genetic elements carrying virulence-associated genes from S. aureus. This includes those encoding the Panton–Valentine leukocidin (PVL), which is associated mainly with severe and/or recurrent staphylococcal skin and soft tissue infections. Here, we describe the genome sequences of two PVL-positive, mecA-negative S. argenteus sequence type (ST) 2250 isolates from the United Arab Emirates in detail. The isolates were found in a dental clinic in the United Arab Emirates (UAE). Both were sequenced using Oxford Nanopore Technology (ONT). This demonstrated the presence of temperate bacteriophages in the staphylococcal genomes, including a PVL prophage. It was essentially identical to the published sequence of phiSa2wa_st78 (GenBank NC_055048), a PVL phage from an Australian S. aureus clonal complex (CC) 88 isolate. Besides the PVL prophage, one isolate carried another prophage and the second isolate carried two additional prophages, whereby the region between these two prophages was inverted. This “flipped” region comprised about 1,083,000 bp, or more than a third of the strain’s genome, and it included the PVL prophage. Prophages were induced by Mitomycin C treatment and subjected to transmission electron microscopy (TEM). This yielded, in accordance to the sequencing results, one or, respectively, two distinct populations of icosahedral phages. It also showed prolate phages which presumptively might be identified as the PVL phage. This observation highlights the significance bacteriophages have as agents of horizontal gene transfer as well as the need for monitoring emerging staphylococcal strains, especially in cosmopolitan settings such as the UAE. Full article

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22 pages, 2000 KiB

Open AccessArticle

Staphylococcus capitis Bloodstream Isolates: Investigation of Clonal Relationship, Resistance Profile, Virulence and Biofilm Formation

by Letícia Calixto Romero, Lucas Porangaba Silva, Nathalia Bibiana Teixeira, Karen Vilegas de Camargo, Milena Aparecida Del Masso Pereira, José Eduardo Corrente, Valéria Cataneli Pereira and Maria de Lourdes Ribeiro de Souza da Cunha

Antibiotics 2024, 13(2), 147; https://doi.org/10.3390/antibiotics13020147 - 1 Feb 2024

Cited by 2 | Viewed by 2632

Abstract

Staphylococcus capitis has been recognized as a relevant opportunistic pathogen, particularly its persistence in neonatal ICUs around the world. Therefore, the aim of this study was to describe the epidemiological profile of clinical isolates of S. capitis and to characterize the factors involved [...] Read more.

Staphylococcus capitis has been recognized as a relevant opportunistic pathogen, particularly its persistence in neonatal ICUs around the world. Therefore, the aim of this study was to describe the epidemiological profile of clinical isolates of S. capitis and to characterize the factors involved in the persistence and pathogenesis of these strains isolated from blood cultures collected in a hospital in the interior of the state of São Paulo, Brazil. A total of 141 S. capitis strains were submitted to detection of the mecA gene and SCCmec typing by multiplex PCR. Genes involved in biofilm production and genes encoding enterotoxins and hemolysins were detected by conventional PCR. Biofilm formation was evaluated by the polystyrene plate adherence test and phenotypic resistance was investigated by the disk diffusion method. Finally, pulsed-field gel electrophoresis (PFGE) was used to analyze the clonal relationship between isolates. The mecA gene was detected in 99 (70.2%) isolates, with this percentage reaching 100% in the neonatal ICU. SCCmec type III was the most prevalent type, detected in 31 (31.3%) isolates and co-occurrence of SCCmec was also observed. In vitro biofilm formation was detected in 46 (32.6%) isolates but was not correlated with the presence of the ica operon genes. Furthermore, biofilm production in ICU isolates was favored by hyperosmotic conditions, which are common in ICUs because of the frequent parenteral nutrition. Analysis of the clonal relationship between the isolates investigated in the present study confirms a homogeneous profile of S. capitis and the persistence of clones that are prevalent in the neonatal ICU and disseminated across the hospital. This study highlights the adaptation of isolates to specific hospital environments and their high clonality. Full article

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2023

Jump to: 2025, 2024

12 pages, 1547 KiB

Open AccessArticle

Longitudinal Study of Antibiotic Resistance of Staphylococci from Cases of Subclinical Mastitis in Sheep in Greece: Incidence and Risk Factors

by Charalambia K. Michael, Daphne T. Lianou, Katerina Tsilipounidaki, Zoe Florou, Natalia G. C. Vasileiou, Vasia S. Mavrogianni, Efthymia Petinaki and George C. Fthenakis

Antibiotics 2023, 12(12), 1703; https://doi.org/10.3390/antibiotics12121703 - 7 Dec 2023

Viewed by 1571

Abstract

The present paper extends a previous publication on a field study of subclinical mastitis in sheep and focuses on the following laboratory characteristics of the staphylococcal isolates: antibiotic resistance and association with biofilm formation. The specific objectives of the present study were (a) [...] Read more.

The present paper extends a previous publication on a field study of subclinical mastitis in sheep and focuses on the following laboratory characteristics of the staphylococcal isolates: antibiotic resistance and association with biofilm formation. The specific objectives of the present study were (a) to describe the incidence of isolation of antibiotic-resistant staphylococci from cases of mastitis throughout the milking period in dairy sheep flocks and (b) to identify relevant risk factors, which would contribute to the sustainable control of the infection. Staphylococcal isolates from subclinical mastitis were evaluated for antibiotic resistance to 18 antibiotics. Antibiotic resistance was detected in 57 of the 179 staphylococcal isolates from subclinical mastitis (31.8%). Resistance was recorded against 11 antibiotics, most often against ampicillin (63.2% of resistant isolates), penicillin (63.2%) and tetracycline (47.4%). Isolates resistant to ampicillin and penicillin were recovered in all 12 farms. Twenty-one multidrug-resistant isolates (11.7%) were also recovered. The incidence risk of isolation of staphylococci resistant to at least one (any) antibiotic throughout the study period was 23.8%. The incidence risk of isolation of staphylococci resistant to oxacillin was 5.0%; that of isolation of multidrug-resistant staphylococci was 8.8%. With regard to increased incidence risk of isolation of staphylococci resistant to at least one (any) antibiotic and increased incidence risk of isolation of staphylococci resistant to oxacillin, the omission of anti-staphylococcal mastitis vaccination of ewes emerged as a risk factor. With regard to increased incidence risk of isolation of multidrug-resistant staphylococci, the following variables emerged as risk factors: (a) higher number of antibiotics used on the farm for the treatment of mastitis and (b) younger age of lambs taken away from their dam. Most biofilm-forming antibiotic-resistant staphylococci were recovered from farms where anti-staphylococcal mastitis vaccination was not applied (55.9% versus 44.1% from farms where anti-staphylococcal mastitis vaccination was applied). Full article

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9 pages, 265 KiB

Open AccessArticle

Occurrence and Antimicrobial Resistance among Staphylococci Isolated from the Skin Microbiota of Healthy Goats and Sheep

by Maria Wesołowska and Ewa Szczuka

Antibiotics 2023, 12(11), 1594; https://doi.org/10.3390/antibiotics12111594 - 5 Nov 2023

Cited by 4 | Viewed by 1785

Abstract

Staphylococci colonize the skin and mucous membranes of different animals. The purpose of this study was to determine the staphylococcal composition of the skin microbiota of healthy, non-vet visiting, and antimicrobially non-treated sheep and goats. In total, 83 strains (44 from goats and [...] Read more.

Staphylococci colonize the skin and mucous membranes of different animals. The purpose of this study was to determine the staphylococcal composition of the skin microbiota of healthy, non-vet visiting, and antimicrobially non-treated sheep and goats. In total, 83 strains (44 from goats and 39 from sheep) were isolated and identified using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The diversity of the isolated Staphylococcus species was relatively high, and only coagulase-negative staphylococci (CoNS) were isolated. In sheep, S. vitulinus (9/39, 23.1%) was the most common species, followed by S. equorum (8/39, 20.5%), S. lentus (7/39, 17.9%), S. sciuri (6/39, 15.4%), S. xylosus (6/39, 15.4%), S. warneri (1/39, 2.6%), S. simulans (1/39, 2.6%), and S. nepalensis (1/39, 2.6%). In the goats, the most common species was S. sciuri, which was detected in 13 (29.5%) animals. The goat skin was also inhabited by S. equorum (7/44, 15.9%), S. vitulinus (6/44, 13.6%), S. cohnii (5/44, 11.4%), S. lentus (4/44, 9.1%), S. suscinus (3/44, 6.8%), S. caprae, (2/44, 4.5%), S. auricularis (2/44, 4.5%), S. warneri (1/44, 2.3%), and S. xylosus (1/44, 2.3%). Only one S. xylosus strain of goat origin carried the enterotoxin gene (sea). Antimicrobial resistance was not common among the isolated staphylococci. Only 31 (37.3%) strains were resistant to at least one antimicrobial agent, with the highest frequency of resistance to penicillin (16.8%), followed by clindamycin (9.6%), erythromycin (8.4%), moxifloxacin (8.4%), and tetracycline (7.2%). All isolates were susceptible to eight antibiotics (amikacin, gentamycin, ciprofloxacin, levofloxacin, rifampicin, chloramphenicol, trimethoprim-sulfamethoxazole, and tigecycline), representing six different classes. Three isolates displayed a multi-resistance phenotype (MDR): the goat isolates S. cohnii and S. sciuri, as well as the ewe isolate S. xylosus. The MDR S. cohnii isolate was found to be methicillin-resistant and carried the mecA gene. Moreover, the staphylococci isolated from the healthy animals carried genes conferring resistance to β-lactams (mecA, blaZ), tetracyclines (tetL, tetK), macrolides (ermB, ermC), lincosamides (lnu), and fluoroquinolones (grlA). However, the prevalence of these genes was low. Full article

13 pages, 2181 KiB

Open AccessArticle

Prevalence of the SigB-Deficient Phenotype among Clinical Staphylococcus aureus Isolates Linked to Bovine Mastitis

by Anna Walzl, Helene Marbach, Darya Belikova, Claus Vogl, Monika Ehling-Schulz, Simon Heilbronner and Tom Grunert

Antibiotics 2023, 12(4), 699; https://doi.org/10.3390/antibiotics12040699 - 3 Apr 2023

Viewed by 2026

Abstract

Phenotypic adaptation has been associated with persistent, therapy-resistant Staphylococcus aureus infections. Recently, we described within-host evolution towards a Sigma factor B (SigB)-deficient phenotype in a non-human host, a naturally infected dairy cow with chronic, persistent mastitis. However, to our knowledge, the prevalence of [...] Read more.

Phenotypic adaptation has been associated with persistent, therapy-resistant Staphylococcus aureus infections. Recently, we described within-host evolution towards a Sigma factor B (SigB)-deficient phenotype in a non-human host, a naturally infected dairy cow with chronic, persistent mastitis. However, to our knowledge, the prevalence of SigB deficiency among clinical S. aureus isolates remains unknown. In this study, we screened a collection of bovine mastitis isolates for phenotypic traits typical for SigB deficiency: decreased carotenoid pigmentation, increased proteolysis, secretion of α-hemolysin and exoproteins. Overall, 8 out of 77 (10.4%) isolates of our bovine mastitis collection exhibited the SigB-deficient phenotype. These isolates were assigned to various clonal complexes (CC8, CC9, CC97, CC151, CC3666). We further demonstrated a strong positive correlation between asp23-expression (a marker of SigB activity) and carotenoid pigmentation (r = 0.6359, p = 0.0008), underlining the role of pigmentation as a valuable predictor of the functional status of SigB. Sequencing of the sigB operon (mazEF-rsbUVW-sigB) indicated the phosphatase domain of the RsbU protein as a primary target of mutations leading to SigB deficiency. Indeed, by exchanging single nucleotides in rsbU, we could either induce SigB deficiency or restore the SigB phenotype, demonstrating the pivotal role of RsbU for SigB functionality. The data presented highlight the clinical relevance of SigB deficiency, and future studies are needed to exploit its role in staphylococcal infections. Full article

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16 pages, 1235 KiB

Open AccessArticle

Staphylococcus aureus in Horses in Nigeria: Occurrence, Antimicrobial, Methicillin and Heavy Metal Resistance and Virulence Potentials

by Obichukwu Chisom Nwobi, Madubuike Umunna Anyanwu, Ishmael Festus Jaja, Innocent Okwundu Nwankwo, Chukwuemeka Calistus Okolo, Chibundo Adaobi Nwobi, Ekene Vivienne Ezenduka and James Wabwire Oguttu

Antibiotics 2023, 12(2), 242; https://doi.org/10.3390/antibiotics12020242 - 24 Jan 2023

Cited by 7 | Viewed by 2521

Abstract

Staphylococcus aureus was isolated from a total of 360 nasal and groin skin swabs from 180 systematic randomly-selected horses slaughtered for meat at Obollo-Afor, Enugu State, Southeast Nigeria and antimicrobial, methicillin and heavy metal resistance profile and virulence potentials of the isolates established. Baird-Parker [...] Read more.

Staphylococcus aureus was isolated from a total of 360 nasal and groin skin swabs from 180 systematic randomly-selected horses slaughtered for meat at Obollo-Afor, Enugu State, Southeast Nigeria and antimicrobial, methicillin and heavy metal resistance profile and virulence potentials of the isolates established. Baird-Parker agar with egg yolk tellurite was used for S. aureus isolation. S. aureus isolates were confirmed biochemically and serologically using a specific S. aureus Staphytect Plus™ latex agglutination test kit. The antimicrobial resistance profile, methicillin, vancomycin and inducible clindamycin resistance, and β-lactamase production of the isolates were determined with disc diffusion. Tolerance to Copper, Cadmium, Lead and Zinc was assessed using the agar dilution method and virulence potentials were determined using phenotypic methods. Forty-three (23.9%) of the 180 horses harbored S. aureus. Some 71 S. aureus were recovered from the 360 samples. Two (2.8%) of the 71 S. aureus were methicillin-resistant S. aureus (MRSA) and 69 (97.2%) were methicillin-susceptible. MRSA was recovered from 2 (1.1%) of the 180 horses. Some 9.4% of the isolates were multiple drug-resistant (MDR). The mean multiple antibiotic resistance indices (MARI) for the isolates was 0.24. Heavy metal resistance rate of the isolates ranged between 35.4–70.4%. The isolates, including the MRSA strains, displayed virulence potentials as clumping factor and catalase, gelatinase, caseinase, heamolysin, and biofilm was at the rate of 100%, 53.5%, 43.7%, 18.3% and 23.9%, respectively. This study showed that a considerable percentage of horses slaughtered in Obollo-Afor Southeastern Nigeria are potential reservoirs of virulent multiple drug- and heavy metal-resistant S. aureus, including MRSA, that could spread to humans and the environment. Full article

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