Nasal Carriage of Staphylococcus aureus among Children in the Ashanti Region of Ghana

Methicillin-Resistant Staphylococcus aureus among Students: Nasal Carriage Rate, Contributing Factors, and Antimicrobial Susceptibility

Background and Objectives: Staphylococcus aureus is a prominent component of the human flora; however, it can cause various pathological conditions. The emergence of methicillin-resistant S. aureus (MR-SA) has been significantly influenced by the overuse and inappropriate administration of antibiotics. The frequency of MR-SA nasal colonization among healthcare workers (HCWs) is increasing, and MR-SA is not restricted to hospital settings, with a notable rise in infections among individuals unrelated to HCWs. This study aimed to assess the prevalence of S. aureus nasal carriage among students at Government College University Faisalabad (GCUF), University of Agriculture Faisalabad (UAF), a Government School (GS), and a Private School (PS) to characterize the phenotypic traits of isolates and evaluate antimicrobial resistance profiles. Materials and Methods: A total of 1200 nasal swabs were inoculated on blood and mannitol salt agar, followed by phenotypic identification of S. aureus and MR-SA using biochemical tests. Antimicrobial susceptibility testing was conducted via the Kirby-Bauer disk diffusion method, and minimum inhibitory concentration (MIC) determination was performed using the broth dilution method. Additionally, nuc and mecA gene amplification through PCR aided in isolate identification. Results: The results revealed that 14% (168) of students harbored S. aureus in their nasal cavities, with 8.5% (102) carrying methicillin-sensitive S. aureus (MSSA) and 5.5% (66) carrying MR-SA. Male students exhibited higher S. aureus (57.7%) and MR-SA (21.4%) prevalence compared to females (42.3% and 17.9%, respectively). Urban students showed a higher S. aureus prevalence (54.2%), while rural students exhibited a higher MR-SA rate (22%). Overall, 80.3% of S. aureus isolates displayed resistance to erythromycin followed by fluoroquinolones (47.6%) and clindamycin (42.2%). All the S. aureus isolates, including MR-SA, remained susceptible to vancomycin and linezolid. PCR results revealed that 95.5% (63) of MR-SA isolates carried the mecA gene. Conclusions: The high prevalence of multi-drug-resistant (MDR) S. aureus raises significant public health concerns, with educational institutions potentially serving as reservoirs for bacterial transmission. The improper use of antibiotics contributes to bacterial resistance and increased infection rates. It is crucial to implement measures to prevent antibiotic misuse and develop comprehensive strategies within educational settings to effectively combat S. aureus and MR-SA prevalence.

Nasal Carriage, Antimicrobial Susceptibility Profile, and Enterotoxin Genes of Staphylococcus aureus Isolated from Children with Asthma

Asthma is a chronic respiratory disease that affects children worldwide. Increasing evidence suggests that Staphylococcus aureus contributes to the pathology of asthma. The aim of this study was to evaluate the nasal carriage, antimicrobial susceptibility profile, and presence of enterotoxin genes from S. aureus isolated from children with asthma. Nasal swab samples were collected from 158 children, including 98 children with asthma and 60 healthy controls. S. aureus isolates were identified using phenotypic methods and the presence of the nuc gene. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Polymerase chain reaction (PCR) confirmed the presence of the mecA gene and enterotoxin genes. The nuc gene was confirmed in 83 isolates, resulting in a nasal carriage of 52.5% (83/158). The nasal carriage of S. aureus was higher among asthma cases (72.4%), with a significant association of S. aureus nasal carriage observed among asthma cases (OR 0.201, 95% CI 0.063-0.645, p = 0.007). Methicillin-resistant S. aureus (MRSA) nasal carriage was 11.4%. The S. aureus isolates showed high resistance to cefoxitin (99%) and penicillin (92%) but were sensitive to gentamicin (25%). Furthermore, 67.5% of the isolates were multi-drug resistant. The staphylococcal enterotoxin c gene (sec) was the most prevalent enterotoxin (19.7%) among cases and controls. These findings highlight the need for improved antibiotic stewardship in paediatric medicine and implementation of infection control policies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01272-z.

Proven anti-virulence therapies in combating methicillin- and vancomycin-resistant Staphylococcus aureus infections

Introduction

Despite years of efforts to develop new antibiotics for eradicating multidrug-resistant (MDR) and multi-virulent Methicillin-Resistant Staphylococcus aureus (MRSA) and Vancomycin-Resistant Staphylococcus aureus (VRSA) infections, treatment failures and poor prognoses in most cases have been common. Therefore, there is an urgent need for new therapeutic approaches targeting virulence arrays. Our aim is to discover new anti-virulence therapies targeting MRSA and VRSA virulence arrays.

Methodology

We employed phenotypic, molecular docking, and genetic studies to screen for anti-virulence activities among selected promising compounds: Coumarin, Simvastatin, and Ibuprofen.

Results

We found that nearly all detected MRSA and VRSA strains exhibited MDR and multi-virulent profiles. The molecular docking results aligned with the phenotypic and genetic assessments of virulence production. Biofilm and hemolysin productions were inhibited, and all virulence genes were downregulated upon treatment with sub-minimum inhibitory concentration (sub-MIC) of these promising compounds. Ibuprofen was the most active compound, exhibiting the highest inhibition and downregulation of virulence gene products. Moreover, in vivo and histopathological studies confirmed these results. Interestingly, we observed a significant decrease in wound area and improvements in re-epithelialization and tissue organization in the Ibuprofen and antimicrobial treated group compared with the group treated with antimicrobial alone. These findings support the idea that a combination of Ibuprofen and antimicrobial drugs may offer a promising new therapy for MRSA and VRSA infections.

Conclusion

We hope that our findings can be implemented in clinical practice to assist physicians in making the most suitable treatment decisions.

Nasal carriage of Staphylococcus aureus in healthy dairy cows in Algeria: antibiotic resistance, enterotoxin genes and biofilm formation

BACKGROUND

Staphylococcus aureus can colonize and infect a variety of animal species. In dairy herds, it is one of the leading causes of mastitis cases. The objective of this study was to characterize the S. aureus isolates recovered from nasal swabs of 249 healthy cows and 21 breeders of 21 dairy farms located in two provinces of Algeria (Tizi Ouzou and Bouira).

METHODS

The detection of enterotoxin genes was investigated by multiplex PCRs. Resistance of recovered isolates to 8 antimicrobial agents was determined by disc-diffusion method. The slime production and biofilm formation of S. aureus isolates were assessed using congo-red agar (CRA) and microtiter-plate assay. Molecular characterization of selected isolates was carried out by spa-typing and Multi-Locus-Sequence-Typing (MLST).

RESULTS

S. aureus was detected in 30/249 (12%) and 6/13 (28.6%) of nasal swabs in cows and breeders, respectively, and a total of 72 isolates were recovered from positive samples (59 isolates from cows and 13 from breeders). Twenty-six of these isolates (36.1%) harbored genes encoding for staphylococcal enterotoxins, including 17/59 (28.8%) isolates from cows and 9/13 (69.2%) from breeders. Moreover, 49.1% and 92.3% of isolates from cows and breeders, respectively, showed penicillin resistance. All isolates were considered as methicillin-susceptible (MSSA). Forty-five (76.3%) of the isolates from cows were slime producers and 52 (88.1%) of them had the ability to form biofilm in microtiter plates. Evidence of a possible zoonotic transmission was observed in two farms, since S. aureus isolates recovered in these farms from cows and breeders belonged to the same clonal lineage (CC15-ST15-t084 or CC30-ST34-t2228).

CONCLUSIONS

Although healthy cows in this study did not harbor methicillin-resistant S. aureus isolates, the nares of healthy cows could be a reservoir of enterotoxigenic and biofilm producing isolates which could have implications in human and animal health.

Multilocus-sequence typing reveals clonality of Staphylococcus aureus in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is exacerbated by Staphylococcus aureus, which is capable of displacing not only the physiological microbiota, but also other strains of its own species. Analyses of the molecular characteristics and relationships of S. aureus strains present in different microniches are lacking.

OBJECTIVES

To determine, using multilocus sequence typing (MLST), the relationship of S. aureus isolates from the lesional and nonlesional skin and anterior nares of patients with AD, and to review the characteristics of the dominant clones.

METHODS

Sixty-three individuals with active AD were enrolled. Ten patients with moderate-to-severe AD (SCoring of Atopic Dermatitis score ≥ 25) colonized by S. aureus in all analysed locations were included in the MLST analysis.

RESULTS

The most prevalent sequence types were 7 (10/30 strains; 33.3%), 15 and 97 (both 5/30 strains; 16.7%) all of which were associated with the expression of adhesins and toxins promoting chronic microbial dysbiosis, skin barrier damage and inflammation. Six patients (60%) were carriers of clonal S. aureus strains at all analysed locations, three (30%) carriers in lesional and nonlesional skin, and one (10%) was a carrier in nonlesional skin and the anterior nares.

CONCLUSIONS

The results imply that the identified S. aureus lineages are better adapted to dominate the microbiota in AD. Decontaminating the identified reservoirs of S. aureus (i.e. anterior nares and nonlesional skin) could reduce the severity of AD.

Occurrence, Antibiotic Susceptibility, Biofilm Formation and Molecular Characterization of Staphylococcus aureus Isolated from Raw Shrimp in China

The aim of this study was to determine the prevalence and characterization of Staphylococcus aureus isolated from 145 shrimp samples from 39 cities in China. The results show that 41 samples (28%) from 24 cities were positive, and most of the positive samples (39/41, 95.1%) were less than 110 MPN/g. Antimicrobial susceptibility testing showed that only seven isolates were susceptible to all 24 antibiotics, whereas 65.1% were multidrug-resistant. Antibiotic resistance genes that confer resistance to β-lactams, aminoglycosides, tetracycline, macrolides, lincosamides and streptogramin B (MLSB), trimethoprim, fosfomycin and streptothricin antibiotics were detected. All S. aureus isolates had the ability to produce biofilm and harbored most of the biofilm-related genes. Genes encoding one or more of the important virulence factors staphylococcal enterotoxins (sea, seb and sec), toxic shock syndrome toxin 1 (tsst-1) and Panton-Valentine leukocidin (PVL) were detected in 47.6% (30/63) of the S. aureus isolates. Molecular typing showed that ST15-t085 (27.0%, 17/63), ST1-t127 (14.3%, 9/63) and ST188-t189 (11.1%, 7/63) were the dominant genetic types. The finding of this study provides the first comprehensive surveillance on the incidence of S. aureus in raw shrimp in China. Some retained genotypes found in this food have been linked to human infections around the world.

Co-carriage of Staphylococcus aureus and Streptococcus pneumoniae among children younger than 2 years of age in a rural population in Pakistan

Objectives

Staphylococcus aureus and Streptococcus pneumoniae are common colonizers of the human nasopharynx. In this study, we describe S. aureus nasopharyngeal carriage and evaluate its association with S. pneumoniae carriage post-10-valent pneumococcal conjugate vaccine (PCV10) introduction in Pakistan.

Methods

A serial cross-sectional study was undertaken from 2014 to 2018, children <2 years were randomly selected, and nasopharyngeal swabs were collected using standard WHO guidelines. S. aureus and S. pneumoniae isolates were identified using standard methods and tested for antimicrobial susceptibility by the standard Kirby-Bauer disk-diffusion method as per Clinical & Laboratory Standards Institute (CLSI) recommendations. Regression analysis was used to determine predictors associated with S. aureus carriage.

Results

We enrolled 3140 children. S. aureus carriage prevalence was 5.6% (176/3140), and 50.1% (81/176) of the isolates were methicillin-resistant S. aureus (MRSA). S. aureus carriage was higher in the absence of pneumococcus compared to isolates in which pneumococcus was present (7.5% vs 5.0%). S. aureus carriage was negatively associated with pneumococcal carriage, being in 3rd and 4th year of enrollment, and vaccination with two and three PCV10 doses, in addition, fast breathing, ≥2 outpatients visits, and rainy season were positively associated. The following resistance rates were observed: 98.9% for penicillin, 74.4% for fusidic acid, and 23.3% for gentamicin, 10.2% for erythromycin, and 8.5% for cotrimoxazole. All isolates were susceptible to amikacin.

Conclusions

Overall S. aureus carriage prevalence was low, PCV10 vaccine was protective against the carriage. The proportion of MRSA carriage and antimicrobial resistance was high in this community warranting continuous monitoring for invasive infections.

Staphylococcus aureus sequence type (ST) 45, ST30, and ST15 in the gut microbiota of healthy infants - persistence and population counts in relation to ST and virulence gene carriage

Staphylococcus aureus colonizes the anterior nares, and also the gut, particularly in infants. S. aureus is divided into lineages, termed clonal complexes (CCs), which comprise closely related sequence types (STs). While CC30 and CC45 predominate among nasal commensals, their prevalence among gut-colonizing S. aureus is unknown. Here, 67 gut commensal S. aureus strains from 49 healthy Swedish infants (aged 3 days to 12 months) were subjected to multi-locus sequence typing. The STs of these strains were related to their virulence gene profiles, time of persistence in the microbiota, and fecal population counts. Three STs predominated: ST45 (22% of the strains); ST15 (21%); and ST30 (18%). In a logistic regression, ST45 strains showed higher fecal population counts than the others, independent of virulence gene carriage. The lower fecal counts of ST15 were linked to the carriage of fib genes (encoding fibrinogen-binding proteins), while those of ST30 were linked to fib and sea (enterotoxin A) carriage. While only 11% of the ST15 and ST30 strains were acquired after 2 months of age, this was true of 53% of the ST45 strains (p = 0.008), indicating that the former may be less fit for establishment in a more mature microbiota. None of the ST45 strains was transient (persisting < 3 weeks), and persistent ST45 strains colonized for significantly longer periods than persistent strains of other STs (mean, 34 vs 22 weeks, p = 0.04). Our results suggest that ST45 strains are well-adapted for commensal gut colonization in infants, reflecting yet-unidentified traits of these strains.

Genetic Diversity and Virulence Profile of Methicillin and Inducible Clindamycin-Resistant Staphylococcus aureus Isolates in Western Algeria

Staphylococcusaureus causes a wide range of life-threatening infections. In this study, we determined its prevalence in the hospital environment and investigated nasal carriage among healthcare workers and patients admitted to a hospital in western Algeria. A total of 550 specimens were collected. An antibiogram was performed and the genes encoding resistance to methicillin, inducible clindamycin and toxins were sought among the 92 S. aureus isolates. The spread of clones with a methicillin- and/or clindamycin-resistance phenotype between these ecosystems was studied using genomic analysis. A prevalence of 27%, 30% and 13% of S. aureus (including 2.7%, 5% and 1.25% of MRSA) in patients, healthcare workers and the hospital environment were observed, respectively. The presence of the mecA, erm, pvl and tsst-1 genes was detected in 10.9%, 17.4%, 7.6% and 18.5% of samples, respectively. Sequencing allowed us to identify seven sequence types, including three MRSA-IV-ST6, two MRSA-IV-ST80-PVL+, two MRSA-IV-ST22-TSST-1, two MRSA-V-ST5, and one MRSA-IV-ST398, as well as many virulence genes. Here, we reported that both the hospital environment and nasal carriage may be reservoirs contributing to the spread of the same pathogenic clone persisting over time. The circulation of different pathogenic clones of MRSA, MSSA, and iMLSB, as well as the emergence of at-risk ST398 clones should be monitored.

A 6-Year Update on the Diversity of Methicillin-Resistant Staphylococcus aureus Clones in Africa: A Systematic Review

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of hospital-associated (HA) and community-associated (CA) infections globally. The multi-drug resistant nature of this pathogen and its capacity to cause outbreaks in hospital and community settings highlight the need for effective interventions, including its surveillance for prevention and control. This study provides an update on the clonal distribution of MRSA in Africa.

Methods

A systematic review was conducted by screening for eligible English, French, and Arabic articles from November 2014 to December 2020, using six electronic databases (PubMed, EBSCOhost, Web of Science, Scopus, African Journals Online, and Google Scholar). Data were retrieved and analyzed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines (registered at PROSPERO: CRD42021277238). Genotyping data was based primarily on multilocus sequence types (STs) and Staphylococcal Cassette Chromosome mec (SCCmec) types. We utilized the Phyloviz algorithm in the cluster analysis and categorization of the MRSA STs into various clonal complexes (CCs).

Results

We identified 65 studies and 26 publications from 16 of 54 (30%) African countries that provided sufficient genotyping data. MRSA with diverse staphylococcal protein A (spa) and SCCmec types in CC5 and CC8 were reported across the continent. The ST5-IV [2B] and ST8-IV [2B] were dominant clones in Angola and the Democratic Republic of Congo (DRC), respectively. Also, ST88-IV [2B] was widely distributed across the continent, particularly in three Portuguese-speaking countries (Angola, Cape Verde, and São Tomé and Príncipe). The ST80-IV [2B] was described in Algeria and Egypt, while the HA-ST239/ST241-III [3A] was only identified in Egypt, Ghana, Kenya, and South Africa. ST152-MRSA was documented in the DRC, Kenya, Nigeria, and South Africa. Panton-Valentine leukocidin (PVL)-positive MRSA was observed in several CCs across the continent. The median prevalence of PVL-positive MRSA was 33% (ranged from 0 to 77%; n = 15).

Conclusion

We observed an increase in the distribution of ST1, ST22, and ST152, but a decline of ST239/241 in Africa. Data on MRSA clones in Africa is still limited. There is a need to strengthen genomic surveillance capacity based on a "One-Health" strategy to prevent and control MRSA in Africa.

Investigation of Virulence Genes of Staphylococcus aureus Isolated from Sterile Body Fluid Samples and Their Correlation with Clinical Symptoms and Outcomes

Staphylococcus aureus is the major pathogen causing nosocomial human infections and produces a variety of virulence factors that contribute to its ability to colonize and cause diseases. This study was conducted to investigate the virulence genes in S. aureus isolated from sterile body fluid samples and their correlation with clinical symptoms and outcomes. The VITEK 2® Compact system was used to perform biochemical identification and antimicrobial susceptibility tests on 33 S. aureus isolates. Virulence genes were amplified using multiplex PCR. The virulence gene patterns were analyzed by systematic cluster analysis. The frequency of methicillin-resistant S. aureus was 45.45%, and 17 virulence genes were identified. Genes encoding hemolysins showed high frequencies. The frequencies of hla, hlb, hld, and hlgB were 93.94% and that of the luk-F/S-PV was 21.21%. Except for the frequency of splB (51.52%), the remaining genes encoding invasive proteases showed frequencies greater than 81.82%. Among the patients, 100.00% had undergone invasive medical procedures and 24.00% had been treated with more than three types of antibiotic drugs. Invasive medical procedures are the main causes of infection. Resistance to antibiotic drugs and the status of carrying virulence genes were highly related to clinical symptoms and outcomes.

Nasopharyngeal colonisation dynamics of bacterial pathogens in patients with fever in rural Burkina Faso: an observational study

Background

Nasopharyngeal colonisation with clinically relevant bacterial pathogens is a risk factor for severe infections, such as pneumonia and bacteraemia. In this study, we investigated the determinants of nasopharyngeal carriage in febrile patients in rural Burkina Faso.

Methods

From March 2016 to June 2017, we recruited 924 paediatric and adult patients presenting with fever, hypothermia or suspicion of severe infection to the Centre Medical avec Antenne Chirurgicale Saint Camille de Nanoro, Burkina Faso. We recorded a broad range of clinical data, collected nasopharyngeal swabs and tested them for the presence of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and Klebsiella pneumoniae by quantitative polymerase chain reaction. Using logistic regression, we investigated the determinants of carriage and aimed to find correlations with clinical outcome.

Results

Nasopharyngeal colonisation with S. pneumoniae, H. influenzae and M. catarrhalis was highly prevalent and strongly dependent on age and season. Females were less likely to be colonised with S. pneumoniae (OR 0.71, p = 0.022, 95% CI 0.53–0.95) and M. catarrhalis (OR 0.73, p = 0.044, 95% CI 0.54–0.99) than males. Colonisation rates were highest in the age groups < 1 year and 1–2 years of age and declined with increasing age. Colonisation also declined towards the end of the rainy season and rose again during the beginning of the dry season. K. pneumoniae prevalence was low and not significantly correlated with age or season. For S. pneumoniae and H. influenzae, we found a positive association between nasopharyngeal carriage and clinical pneumonia [OR 1.75, p = 0.008, 95% CI 1.16–2.63 (S. pneumoniae) and OR 1.90, p = 0.004, 95% CI 1.23–2.92 (H. influenzae)]. S. aureus carriage was correlated with mortality (OR 4.01, p < 0.001, 95% CI 2.06–7.83), independent of bacteraemia caused by this bacterium.

Conclusions

Age, sex and season are important determinants of nasopharyngeal colonisation with S. pneumoniae, H. influenzae and M. catarrhalis in patients with fever in Burkina Faso. S. pneumoniae and H. influenzae carriage is associated with clinical pneumonia and S. aureus carriage is associated with mortality in patients with fever. These findings may help to understand the dynamics of colonisation and the associated transmission of these pathogens. Furthermore, understanding the determinants of nasopharyngeal colonisation and the association with disease could potentially improve the diagnosis of febrile patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06996-7.

Genetic Characterization of Staphylococcus aureus From Subclinical Mastitis Cases in Dairy Cows in Rwanda

Whole-genome sequencing was carried out on 30 Staphylococcus (S.) aureus isolates from dairy cows with subclinical mastitis from all five provinces of Rwanda. Twenty-five of the isolates produced enough sequence to be analyzed using core genome multilocus sequence typing (cg-MLST). The isolates group into three main clusters. The largest cluster contain isolates of sequence type (ST) 152 (n = 6) and the closely related ST1633 (n = 2). These sequence types have previously mainly been encountered in humans. The isolates of the second-largest cluster belong to ST5477 (n = 5),so far exclusively isolated from cows in Rwanda. The third cluster consists of isolates of ST97 (n = 4), which is a well-known bovine-adapted sequence type. These three clusters were all widespread over the country. Isolates of the usually human-adapted sequence types 1 (n = 2) and 5 (n= 1) were found and a single isolate of ST2430, previously found among humans in Africa. Finally, four isolates of novel sequence types were found: ST7108 (n = 2), ST7109 (n = 1), and ST7110 (n = 1). The blaZ penicillin resistance gene was found in 84% of the isolates and was in all cases corroborated by phenotypic resistance determination. Five (20%) of the isolates carried a tetracycline resistance gene, tet(K) or tetM, and three of these five also displayed phenotypic resistance while two isolates carried a tetM-gene but were yet tetracycline susceptible. Seven (28%) isolates carried the dfrG gene conferring resistance to trimethoprim. Four of these isolates indeed were resistant to trimethoprim while three isolates were sensitive. The str gene conferring resistance to aminoglycosides was found in three isolates; however, none of these displayed resistance to gentamycin. Our data revealed a high diversity of the sequence types of S. aureus isolates from cows with subclinical mastitis in Rwanda. Two major clusters of ST97 and ST5477 are likely to be bovine adapted and cause mastitis while the third cluster of ST152 usually have been found in humans and may signify a recent transmission of these types from human to cows, for example from hand milking. The high prevalence of this sequence type among dairy cows may pose zoonotic threat. The sequence types were widely distributed without any geographic correlation. Penicillin resistance, the most common type of resistance with a prevalence over 80%, but also tetracycline and trimethoprim resistance were displayed by several isolates.

Impact of mass administration of azithromycin as a preventive treatment on the prevalence and resistance of nasopharyngeal carriage of Staphylococcus aureus

Staphylococcus aureus is a major cause of serious illness and death in children, indicating the need to monitor prevalent strains, particularly in the vulnerable pediatric population. Nasal carriage of S. aureus is important as carriers have an increased risk of serious illness due to systemic invasion by this pathogen and can transmit the infection. Recent studies have demonstrated the effectiveness of azithromycin in reducing the prevalence of nasopharyngeal carrying of pneumococci, which are often implicated in respiratory infections in children. However, very few studies of the impact of azithromycin on staphylococci have been undertaken. During a clinical trial under taken in 2016, nasal swabs were collected from 778 children aged 3 to 59 months including 385 children who were swabbed before administration of azithromycin or placebo and 393 after administration of azithromycin or placebo. Azithromycin was given in a dose of 100 mg for three days, together with the antimalarials sulfadoxine-pyrimethamine and amodiaquine, on four occasions at monthly intervals during the malaria transmission season. These samples were cultured for S. aureus as well as for the pneumococcus. The S. aureus isolates were tested for their susceptibility to azithromycin (15 g), penicillin (10 IU), and cefoxitine (30 g) (Oxoid Ltd). S. aureus was isolated from 13.77% (53/385) swabs before administration of azithromycin and from 20.10% (79/393) six months after administration (PR = 1.46 [1.06; 2.01], p = 0.020). Azithromycin resistance found in isolates of S. aureus did not differ significantly before and after intervention (26.42% [14/53] vs 16.46% [13/79], (PR = 0.62 [0.32; 1.23], p = 0.172). Penicillin resistance was very pronounced, 88.68% and 96.20% in pre-intervention and in post-intervention isolates respectively, but very little Methicillin Resistance (MRSA) was detected (2 cases before and 2 cases after intervention). Monitoring antibiotic resistance in S. aureus and other bacteria is especially important in Burkina Faso due to unregulated consumption of antibiotics putting children and others at risk.

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.

Nasal Carriage and Methicillin Resistance of Staphylococcus aureus among Schoolchildren in Sana'a City, Yemen

Background

Staphylococcus aureus (S. aureus) is a frequent cause of serious health problems with high morbidity and mortality. The risk of S. aureus infections is increased with the emergence of methicillin-resistant S. aureus (MRSA). This study aims to determine the nasal carriage rate of both S. aureus and MRSA among schoolchildren in Sana'a city.

Methods

This is a cross-sectional study conducted from January 2018 to May 2020. Five hundred and thirty-six students were enrolled. Their age ranged from 5 to 19 years with the mean age and standard deviation equal to 13.3 ± 3.5 years. Nasal swabs were collected from each student for culturing and methicillin susceptibility testing.

Results

Students with positive culture were 271 (51%) males and 265 (49%) females. S. aureus was isolated from 129 (24%) students whereas the overall prevalence of MRSA was 8 (1.5%). S. aureus was significantly recovered from students at the age group of 10–14 years (χ² = 7.02; p=0.03), females than males (OR = 1.96; χ² = 10.75; p=0.001), and students who were admitted into hospitals (OR = 1.6; χ² = 4.89; p=0.03). Nevertheless, there were no significant differences between MRSA carriage and students' age (χ² = 2.3; p=0.32), gender (OR = 1.02; χ² = 0.001; p=0.63), and hospital admission (OR = 1.4; χ² = 0.25; p=0.62).

Conclusions

The prevalence of MRSA is low among schoolchildren in Sana'a city. Age, gender, and previous hospital admission were statistically associated with nasal carriage of S. aureus but not MRSA nasal carriage.

Nasopharyngeal Carriage of Methicillin-Resistant Staphylococcus aureus (MRSA) among Sickle Cell Disease (SCD) Children in the Pneumococcal Conjugate Vaccine Era

The aim of this cross-sectional study was to investigate Staphylococcus aureus nasopharyngeal carriage epidemiology in relation to other nasopharyngeal bacterial colonizers among sickle cell disease (SCD) children about five years into pneumococcal conjugate vaccine 13 (PCV-13) introduction in Ghana. The study involved bacteriological culture of nasopharyngeal swabs obtained from 202 SCD children recruited from the Princess Marie Louise Children's Hospital. S. aureus isolates were identified using standard methods and subjected to antimicrobial susceptibility testing using the Kirby-Bauer disc diffusion method. Cefoxitin-resistant S. aureus isolates were screened for carriage of the mecA, pvl, and tsst-1 genes using multiplex polymerase chain reaction. The carriage prevalence of S. aureus was 57.9% (n = 117), and that of methicillin-resistant S. aureus (MRSA) was 3.5% (n = 7). Carriage of the mecA, pvl, and tsst-1 genes were respectively demonstrated in 20.0% (n = 7), 85.7% (n = 30), and 11.4% (n = 4) of the cefoxitin-resistant S. aureus isolates. PCV-13 vaccination (OR = 0.356, p = 0.004) and colonization with coagulase-negative staphylococci (CoNS) (OR = 0.044, p < 0.0001) each protected against S. aureus carriage. However, none of these and other features of the participants emerged as a determinant of MRSA carriage. The following antimicrobial resistance rates were observed in MRSA compared to methicillin-sensitive S. aureus: clindamycin (28.6% vs. 4.3%), erythromycin (42.9% vs. 19.1%), tetracycline (100% vs. 42.6%), teicoplanin (14.3% vs. 2.6%), penicillin (100% vs. 99.1%), amoxiclav (28.6% vs. 3.5%), linezolid (14.3% vs. 0.0%), ciprofloxacin (42.9% vs. 13.9%), and gentamicin (42.9% vs. 13.0%). The proportion of S. aureus isolates that were multidrug resistant was 37.7% (n = 46). We conclude that S. aureus was the predominant colonizer of the nasopharynx of the SCD children, warranting the continuous monitoring of this risk group for invasive S. aureus infections.

Nasopharyngeal Carriage and Antimicrobial Susceptibility Profile of Staphylococcus aureus among Children under Five Years in Accra

This cross-sectional study investigated the Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) nasopharyngeal carriage epidemiology in Accra approximately five years post-pneumococcal conjugate vaccines introduction in the country. Archived nasopharyngeal swabs collected from 410 children aged under five years old were bacteriologically cultured. The resultant S. aureus isolates were subjected to antimicrobial susceptibility testing and screening for carriage of the mecA and LukF-PV (pvl) genes, following standard procedures. The data obtained were analyzed with Statistical Products and Services Solutions (SPSS) using descriptive statistics and Chi square tests of associations. The isolated bacteria decreased across coagulase-negative Staphylococci (47.3%, n = 194), S. aureus (23.2%, n = 95), Diphtheroids (5.4%, n = 22), Micrococcus species (3.7%, n = 15), Klebsiella pneumoniae (3.2%, n = 13), Moraxella species and Citrobacter species (1.5% each, n = 6), Escherichia coli, Enterobacter species, and Pseudomonas species (0.9% each, n = 2). The MRSA carriage prevalence was 0.49% (n = 2). Individuals aged 37-48 months recorded the highest proportion of S. aureus carriage (32.6%, 31/95). Resistance of S. aureus to the antibiotics tested were penicillin G (97.9%, n = 93), amoxiclav (20%, n = 19), tetracycline (18.9%, n = 18), erythromycin (5.3%, n = 5), ciprofloxacin (2.1%, n = 2), gentamicin (1.1%, n = 1), cotrimoxazole, clindamycin, linezolid, and teicoplanin (0% each). No inducible clindamycin resistance was observed for the erythromycin-resistant isolates. Three (3.2%) of the isolates were multidrug resistant, of which 66.7% (2/3) were MRSA. The pvl gene was associated with 59.14% (55/93) of the methicillin-sensitive S. aureus (MSSA) isolates, but was not detected among any of the MRSA isolates.

Phenotypic and Molecular Characteristics of Community-Associated Staphylococcus aureus Infection in Neonates

Background

Staphylococcus aureus is an important human pathogen causing a wide variety of diseases ranging from mild skin infections to life-threatening bacteremia. This study aimed to provide insight into the phenotype-genotype characteristics of S. aureus isolated from neonates.

Methods

A hospital-based retrospective study was conducted to recruit neonatal patients with community-associated S. aureus infection. All 92 S. aureus clinical isolates were tested for antimicrobial susceptibility, resistance genes, virulence genes, and multilocus sequence typing.

Results

A total of 92 S. aureus isolates were included in this study, including 29 (31.5%) MRSA isolates. Most S. aureus isolates were susceptible to gentamicin, and most methicillin-resistant S. aureus (MRSA) isolates were susceptible to vancomycin and linezolid. The predominant S. aureus genotypes were CC188 (ST188), CC59 (ST338), CC5 (ST5), CC88 (ST8), and CC6 (ST6), with CC59 (ST338) as the most prevalent MRSA. We observed a significantly corresponding relationship between clonal complexes and resistance patterns (such as CC45/CC59/CC121/CC630 associated with multidrug resistance) or the number of virulence genes (such as CC1/CC5/CC45/CC59/CC88 associated with harboring 5-7 virulence genes, and CC22/CC25/CC121 associated with carrying 8-13 genes). Moreover, both univariate and multivariate analyses indicated that invasive S. aureus isolates were significantly associated with resistance to several classes of antibiotics and carrying specific virulence factors.

Conclusion

Our findings provide insight into phenotype-genotype characteristics for S. aureus isolates so as to provide new ideas for differentiating potential genetic backgrounds and monitoring new epidemiologic trends.

Molecular Characterization of Staphylococcus aureus Isolated from Chronic Infected Wounds in Rural Ghana

BACKGROUND

Globally, Staphylococcus aureus is an important bacterial pathogen causing a wide range of community and hospital acquired infections. In Ghana, resistance of S. aureus to locally available antibiotics is increasing but the molecular basis of resistance and the population structure of S. aureus in particular in chronic wounds are poorly described. However, this information is essential to understand the underlying mechanisms of resistance and spread of resistant clones. We therefore subjected 28 S. aureus isolates from chronic infected wounds in a rural area of Ghana to whole genome sequencing.

RESULTS

Overall, resistance of S. aureus to locally available antibiotics was high and 29% were Methicillin resistant Staphylococcus aureus (MRSA). The most abundant sequence type was ST88 (29%, 8/28) followed by ST152 (18%, 5/28). All ST88 carried the mecA gene, which was associated with this sequence type only. Chloramphenicol resistance gene fexB was exclusively associated with the methicillin-resistant ST88 strains. Panton-Valentine leukocidin (PVL) carriage was associated with ST121 and ST152. Other detected mechanisms of resistance included dfrG, conferring resistance to trimethoprim.

CONCLUSIONS

This study provides valuable information for understanding the population structure and resistance mechanisms of S. aureus isolated from chronic wound infections in rural Ghana.

NASAL CARRIAGE OF MULTI-DRUG RESISTANT PANTON VALENTINE LEUKOCIDIN POSITIVE STAPHYLOCOCCUS AUREUS IN HEALTHY INDIVIDUALS OF TUDUN-WADA, GOMBE STATE, NIGERIA

Background:

Panton-Valentine Leucocidin (PVL)-producing Staphylococcus aureus strains have been implicated in serious community-associated invasive infections and their increasing multidrug resistance is a major global health concern. Thus, we investigated the prevalence of the PVL gene and the antimicrobial resistance profile of nasal S. aureus isolates from healthy adults in Tundu-Wada, Gombe State of Nigeria.

Methods and Materials:

A total of 262 nasal samples from healthy adults were obtained and cultured. The isolates were identified as S. aureus by standard morphological and biochemical methods alongside with the Polymerase Chain Reaction (PCR) amplification of their 16S rRNA gene. Antimicrobial susceptibility testing was performed by the disc diffusion technique and the presence of mecA and PVL genes was determined by PCR analysis.

Results:

The overall nasal colonization of S. aureus was 17.6%. The prevalence of haemolysin and biofilm production among the isolates was 25(54.3%) and 42(91.3%), respectively. Only 2(4.3%) and 5(10.9%) possessed mecA and PVL genes respectively but none of the isolates harboured these two genes. All the isolates were resistant to amoxicillin but were highly susceptible (93.7%) to gentamicin. The prevalence of multi-drug resistance (MDR) among the isolates was M 45.7% and all PVL-producing isolates were MDR while one of the isolates with mecA gene exhibited extensive-drug resistance (XDR).

Conclusion:

This is the first report of nasal colonization of MDR PVL-producing S. aureus in healthy adults in Gombe, Northeastern Nigeria. This study highlights the importance of routine surveillance of healthy populations to provide useful strategies for controlling the spread of virulent multidrug-resistant organisms within the community.

Regional Variation of Extended-Spectrum Beta-Lactamase (ESBL)-Producing Enterobacterales, Fluoroquinolone-Resistant Salmonella enterica and Methicillin-Resistant Staphylococcus aureus Among Febrile Patients in Sub-Saharan Africa

Background

Antimicrobial resistance (AMR) thwarts the curative power of drugs and is a present-time global problem. We present data on antimicrobial susceptibility and resistance determinants of bacteria the WHO has highlighted as being key antimicrobial resistance concerns in Africa, to strengthen knowledge of AMR patterns in the region.

Methods

Blood, stool, and urine specimens of febrile patients, aged between ≥ 30 days and ≤ 15 years and hospitalized in Burkina Faso, Gabon, Ghana, and Tanzania were cultured from November 2013 to March 2017 (Patients > 15 years were included in Tanzania). Antimicrobial susceptibility testing was performed for all Enterobacterales and Staphylococcus aureus isolates using disk diffusion method. Extended-spectrum beta-lactamase (ESBL) production was confirmed by double-disk diffusion test and the detection of bla_CTX–M, bla_TEM and bla_SHV. Multilocus sequence typing was conducted for ESBL-producing Escherichia coli and Klebsiella pneumoniae, ciprofloxacin-resistant Salmonella enterica and S. aureus. Ciprofloxacin-resistant Salmonella enterica were screened for plasmid-mediated resistance genes and mutations in gyrA, gyrB, parC, and parE. S. aureus isolates were tested for the presence of mecA and Panton-Valentine Leukocidin (PVL) and further genotyped by spa typing.

Results

Among 4,052 specimens from 3,012 patients, 219 cultures were positive of which 88.1% (n = 193) were Enterobacterales and 7.3% (n = 16) S. aureus. The prevalence of ESBL-producing Enterobacterales (all CTX-M15 genotype) was 45.2% (14/31; 95% CI: 27.3, 64.0) in Burkina Faso, 25.8% (8/31; 95% CI: 11.9, 44.6) in Gabon, 15.1% (18/119; 95% CI: 9.2, 22.8) in Ghana and 0.0% (0/12; 95% CI: 0.0, 26.5) in Tanzania. ESBL positive non-typhoid Salmonella (n = 3) were detected in Burkina Faso only and methicillin-resistant S. aureus (n = 2) were detected in Ghana only. While sequence type (ST)131 predominated among ESBL E. coli (39.1%;9/23), STs among ESBL K. pneumoniae were highly heterogenous. Ciprofloxacin resistant nt Salmonella were commonest in Burkina Faso (50.0%; 6/12) and all harbored qnrB genes. PVL were found in 81.3% S. aureus.

Conclusion

Our findings reveal a distinct susceptibility pattern across the various study regions in Africa, with notably high rates of ESBL-producing Enterobacterales and ciprofloxacin-resistant nt Salmonella in Burkina Faso. This highlights the need for local AMR surveillance and reporting of resistances to support appropriate action.

Molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus among children with respiratory tract infections in southwest China

BACKGROUND

The molecular characteristics and antimicrobial susceptibility of Staphylococcus aureus (S. aureus) in general pediatric wards and county-level hospitals were rarely reported in China.

METHODS

Staphylococcus aureus was isolated from children hospitalized with respiratory tract infection (RTI) in Zhongjiang and Youyang counties in 2015. All isolates were typed by multilocus sequence, staphylococcal protein A, accessory gene regulator (agr), and staphylococcal cassette chromosome mec [SCCmec, for methicillin-resistant S. aureus (MRSA) only]. Polymerase chain reaction was used to screen 21 super-antigen (SAg) genes and panton-valentine leukocidin (pvl). Antimicrobial susceptibility testing was performed by E test.

RESULTS

A total of 2136 children were enrolled. Overall, 125 (5.9%) children carried S. aureus, among which MRSA accounted for 42.4%. ST59-SCCmec type IV-t437-agr group I (58.5%) was the most prevalent genotype in MRSA, and ST188-t189-agr group I (22.2%) was the top genotype in methicillin-sensitive S. aureus (MSSA). The pvl carriage rate in MRSA and MSSA was 15.1% and 9.7%, respectively (P = 0.4112). About 96.8% of S. aureus isolates were positive for at least one SAg gene. The most common SAg gene profile in the dominant ST59 clone was seb-sek-seq (42.8%). All S. aureus isolates were resistant to penicillin and erythromycin (minimum inhibitory concentration 90 was > 32 and 256 mg/L to penicillin and erythromycin, respectively), but usually susceptible to other tested non-β-lactam antimicrobials.

CONCLUSIONS

Staphylococcus aureus and MRSA were detected with a high frequency in children with RTI in county-level hospitals of China. ST59-SCCmec type IV-t437-agr group I was the dominant MRSA clone. The S. aureus isolates exhibited high resistance to penicillin and erythromycin.

Staphylococcus aureus Nasal Colonization among Children with Sickle Cell Disease at the Children's Hospital, Accra: Prevalence, Risk Factors, and Antibiotic Resistance

The aim of this study was to investigate S. aureus carriage among children with sickle cell disease (SCD), including the prevalence, risk factors, and antibiotic resistance. The study was cross-sectional, and involved 120 children with SCD recruited at the Princess Marie Louise Children’s Hospital (PML) in Accra and 100 apparently healthy children from environs of the hospital. Nasal swab samples were collected from the study participants and cultured for bacteria. Confirmation of S. aureus and methicillin-resistant Staphylococcus aureus (MRSA) isolates were done using the tube coagulase test and mecA polymerase chain reaction, respectively. All the S. aureus isolates were tested against standard antimicrobial agents using the Kirby-Bauer method. A structured questionnaire was used to obtain the socio-demographic and clinical data of the study participants. Binary logistic regression was used to identify determinants of S. aureus and MRSA carriage among the study participants. The nasal carriage prevalence of S. aureus was 33.3% (n = 40) and 10% (n = 10) among the participants of the SCD and control groups, respectively. As regards MRSA nasal carriage prevalence, the respective values were 3.33% (n = 4) and 0.00% (n = 0). SCD was significantly associated with S. aureus colonization (p < 0.0001, OR = 4.045), but not MRSA colonization (p = 0.128). In the SCD group, the significant predictors of S. aureus carriage were increasing age (p = 0.003; OR = 1.275) and living in self-contained apartments (p = 0.033; OR = 3.632), whereas male gender (p = 0.018; OR = 0.344) and the practice of self-medication (p = 0.039; OR = 0.233) were protective of S. aureus carriage. In the control group, a history of hospitalization in the past year was a risk factor for the carriage of S. aureus (p = 0.048; OR = 14.333). Among the participants of the SCD and control groups, respectively, the resistance prevalence recorded by S. aureus against the various antibiotics investigated were penicillin (100% each), cotrimoxazole (27.5% vs. 20%), tetracycline (25% vs. 50%), rifampicin (82.5% vs. 50%), erythromycin (30% vs. 20%), clindamycin (32.5% vs. 50%), gentamicin (7.5% vs. 20%), cefoxitin (27.5% vs. 20%), linezolid (30% vs. 40%), and fusidic acid (95% vs. 80%). The proportion of S. aureus isolates that were multidrug resistant (MDR) was 92.5% (37/40) in the SCD group and 100% (10/10) in the control group.

Nasopharyngeal carriage, spa types and antibiotic susceptibility profiles of Staphylococcus aureus from healthy children less than 5 years in Eastern Uganda

Background

Staphylococcus aureus carriage is a known risk factor for staphylococcal disease. However, the carriage rates vary by country, demographic group and profession. This study aimed to determine the S. aureus carriage rate in children in Eastern Uganda, and identify S. aureus lineages that cause infection in Uganda.

Methods

Nasopharyngeal samples from 742 healthy children less than 5 years residing in the Iganga/Mayuge Health and Demographic Surveillance Site in Eastern Uganda were processed for isolation of S. aureus. Antibiotic susceptibility testing based on minimum inhibitory concentrations (MICs) was determined by the BD Phoenix™ system. Genotyping was performed by spa and SCCmec typing.

Results

The processed samples yielded 144 S. aureus isolates (one per child) therefore, the S. aureus carriage rate in children was 19.4% (144/742). Thirty one percent (45/144) of the isolates were methicillin resistant (MRSA) yielding a carriage rate of 6.1% (45/742). All isolates were susceptible to rifampicin, vancomycin and linezolid. Moreover, all MRSA were susceptible to vancomycin, linezolid and clindamycin. Compared to methicillin susceptible S. aureus (MSSA) isolates (68.8%, 99/144), MRSA isolates were more resistant to non-beta-lactam antimicrobials –trimethoprim/sulfamethoxazole 73.3% (33/45) vs. 27.3% (27/99) [p < 0.0001]; erythromycin 75.6% (34/45) vs. 24.2% (24/99) [p < 0.0001]; chloramphenicol 60% (27/45) vs. 19.2% (19/99) [p < 0.0001]; gentamicin 55.6% (25/45) vs. 25.3% (25/99) [p = 0.0004]; and ciprofloxacin 35.6% (16/45) vs. 2% (2/99) [p < 0.0001]. Furthermore, 42 MRSA (93.3%) were multidrug resistant (MDR) and one exhibited high-level resistance to mupirocin. Overall, 61 MSSA (61.6%) were MDR, including three mupirocin and clindamycin resistant isolates. Seven spa types were detected among MRSA, of which t037 and t064 were predominant and associated with SCCmec types I and IV, respectively. Fourteen spa types were detected in MSSA which consisted mainly of t645 and t4353.

Conclusions

S. aureus carriage rate in healthy children in Eastern Uganda is high and comparable to rates for hospitalized patients in Kampala. The detection of mupirocin resistance is worrying as it could rapidly increase if mupirocin is administered in a low-income setting. S. aureus strains of spa types t064, t037 (MRSA) and t645, t4353 (MSSA) are prevalent and could be responsible for majority of staphylococcal infections in Uganda.

Genetic characterisation of staphylococci of food-producing animals in Senegal. PVL detection among MSSA

Background

Food-producing animals can be a vehicle for staphylococcal species as well as their virulence and antimicrobial resistance genes. This work aimed to analyse the diversity of staphylococcal species in food-producing animals in Dakar/Senegal, and to determine the antimicrobial resistance phenotype/genotype and virulence factors of recovered isolates. Nasal samples of 149 cows and 199 chickens (348 animals) were collected from one slaughterhouse and a local market respectively, and were inoculated on selective media for staphylococci recovery. For S. aureus isolates, molecular typing (spa-type, MLST) was performed by PCR/sequencing, and the presence of 27 virulence genes (exfoliative and toxic shock toxins, PVL, haemolysins and enterotoxins) as well as the gene scn were analysed by PCR. Susceptibility to twelve antibiotics was studied by disc-diffusion method for all staphylococci; the resistance genes involved were screened by PCR.

Results

Staphylococcus spp. was present in 3 and 26.8% of chicken and cow nasal samples, respectively. Seven S. aureus isolates and forty isolates of other staphylococcal species were identified. S. aureus isolates were recovered from cow (n = 6) and chicken (n = 1) samples, belonging to four genetic lineages: t084/ST15 (n = 1); t10579/ST291 (n = 3); t355, t4690/ST152 (n = 2); and t6618/ST6 (n = 1). All S. aureus were methicillin-susceptible, penicillin-resistant (blaZ), and two of them were also tetracycline-resistant [tet(K)]. All the isolates carried at least one of the virulence genes tested. The PVL genes were detected in three ST15 and ST152 isolates. They all harboured haemolysins encoding genes and lacked the scn gene. The other staphylococci recovered were S. sciuri (n = 16), S. simulans (n = 11), S. hyicus (n = 5), S. haemolyticus (n = 4), S. chromogenes (n = 3), and S. hominis (n = 1); they were all methicillin-susceptible and 27.5% tetracycline-resistant [tet(K) and tet(L)].

Conclusions

A low prevalence of S. aureus was detected among food-producing animals, all susceptible to methicillin. However, the presence of virulence genes (lukF/lukS-PV, eta, tst, sea and see) is worrisome to the extent that they could be transferred to derived food and therefore, to humans.

Revisiting Bacterial Interference in the Age of Methicillin-resistant Staphylococcus aureus: Insights Into Staphylococcus aureus Carriage, Pathogenicity and Potential Control

Bacteria compete with each other for local supremacy in biologic and environmental niches. In humans, who host an array of commensal bacteria, the presence of one species or strain can sometimes prevent colonization by another, a phenomenon known as "bacterial interference." We describe how, in the 1960s, infants (and later adults) were actively inoculated with a relatively benign strain of Staphylococcus aureus, 502A, to prevent colonization with an epidemic S. aureus strain, 80/81. This introduced bacterial interference as a clinical approach to disease prevention, but little was known about the mechanisms of interference at that time. Since then, much has been learned about how bacteria interact with each other and the host to establish carriage, compete for niches and shift from harmless commensal to invasive pathogen. We provide an overview of these findings and summarize recent studies in which the genome and function of 502A were compared with those of the current epidemic strain, USA300, providing insight into differences in their invasiveness and immunogenicity. Although staphylococcal vaccines have been developed, none has yet been approved for clinical use. Further studies of staphylococcal strains and the molecular characteristics that lead to exclusion of specific bacteria from some niches may provide an alternative path to disease prevention.

Prevalence of Staphylococcus aureus methicillin-sensitive and methicillin-resistant nasal carriage in food handlers in Lebanon: a potential source of transmission of virulent strains in the community

Purpose

To determine the prevalence and virulence determinant genes of nasal colonization by Staphylococcus aureus among food handlers in Tripoli, Lebanon.

Methodology

Within a cross-sectional study design, nasal swab specimens were collected. Epidemiological and microbiological investigations were performed through conventional culture and MALDI-TOF-MS. Antibiotic susceptibility patterns and genetic virulence determinants including enterotoxin genes were also investigated for all isolates.

Results

The data herein show that S. aureus nasal carriage is highly prevalent (23.8 %), and that the rate of methicillin-resistant S. aureus (MRSA) carriage was twice as high as in our last report in 2008. Several enterotoxin genes were detected in five isolates including one MRSA and four methicillin-sensitive S. aureus.

Conclusion

To our knowledge, this is the first investigation in the last decade to examine the carriage prevalence of S. aureus among food handlers in Lebanon. This work reports a concerning level of MRSA, and enterotoxin-producing S. aureus nasal carriage, which could potentially act as a contamination reservoir and lead to food poisoning.

Antibiotic susceptibility patterns of Staphylococcus aureus strains isolated at the Yaounde Central Hospital, Cameroon: a retro prospective study

Introduction

Staphylococcus aureus is an important pathogen responsible for hospital and community acquired infection(s). Emerging resistance to methicillin in this organism has left physicians with few therapeutic alternatives to treat infections caused by it. This study was aimed at determining the antibiotic susceptibility patterns of Staphylococcus aureus strains isolated at the Yaounde Central Hospital, Cameroon.

Methods

from January 2014 to November 2016, a total of 250 non repeated strains were isolated from various clinical specimens. Isolates and antibiotic susceptibility profiles were identified through standard microbiological techniques.

Results

methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) accounted respectively for 80% (201/205) and 20% (49/205) of the total strains isolated. MRSA strains displayed high resistance to cefoxitin (100%), cotrimoxazole (89%), vancomycin (79.7%), lincomycin (70.3%), tobramycin (72.5%), doxycycline (68.0%), kanamycin (69.7%) and erythromycin (55.7%). In contrast, a high susceptibility was observed with rifampicin (82.6%). KTG (42.3%) and constitutive MLSB (17.4%) were the most frequent phenotypes recorded.

Conclusion

our results show that the carriage of acquired MRSA infections predominates in this population. Despite the noticeable multiresistance of MRSA strains to antibiotics, rifampicin remains the drugs of choice for the therapy of acquired MRSA infections in this setting. In order to slow down antimicrobial resistance, surveillance studies for antimicrobial susceptibility remains essential to identify resistance and inform policy on resistance.

Psoitis and multiple venous thromboses caused by Panton Valentine Leukocidin-positive methicillin-sensitive Staphylococcus aureus in a 12-year-old girl: A case report

Panton Valentine Leukocidin (PVL) is one of the many toxins produced by Staphylococcus aureus. In Japan, PVL-positive S. aureus strains are mainly methicillin-resistant S. aureus (MRSA). Data regarding PVL-positive methicillin-sensitive S. aureus (MSSA) are scarce. In this report, we describe a case of severe infection by PVL-positive MSSA. A 12-year-old healthy girl was admitted with high fever and pain in the lower back. Computed tomography revealed a diagnosis of psoitis and multiple venous thromboses. Blood cultures obtained after admission revealed infection with MSSA. Her fever continued despite adequate antibiotic therapy. On the fifth hospitalization day, she developed bladder dysfunction, and an abscess was noted near the third lumbar vertebra. She underwent an emergency operation and recovered. Bacterial analyses revealed that the causative MSSA was a PVL-producing single variant of ST8 (related to USA300clone), of sequence type 2149. PVL is known to cause platelet activation. This case demonstrates the need for detailed analyses of the causative strain of bacteria in cases of S. aureus infection with deep vein thrombosis, even in cases of known MSSA infection.

Colonization of HIV-Infected Children with Methicillin-Resistant Staphylococcus aureus

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) poses a public health threat owing to its extensive resistance to antibiotics, association with persistent outbreaks, and markedly increased healthcare costs. Moreover, HIV-infected individuals are at a greater risk for colonization with MRSA, and may act as reservoirs for subsequent transmission to other individuals. In Ghana, little is known about MRSA in relation to at-risk populations, such as HIV-infected children. The aim of this study was to investigate nasal carriage of S. aureus and MRSA among HIV-infected children in Accra, including the prevalence, risk factors and antibiotic resistance.

METHODOLOGY

The study was cross-sectional, and involved 107 children with HIV infection and an equal number of sex- and age group- matched apparently healthy controls recruited from the Princess Marie Louis Children's Hospital in Accra. Nasal swab specimens were collected from the study participants and cultured for bacteria. S. aureus isolates were confirmed by the coagulase test while MRSA was confirmed by PCR of the mecA gene. Antimicrobial susceptibility testing of S. aureus isolates was done by the Kirby Bauer method. A structured questionnaire was used to collect data on demographic, household and clinical features of the study participants. A logistic regression analysis was performed to identify determinants of S. aureus and MRSA carriage among participants of both study groups.

RESULTS

The carriage prevalence of S. aureus and MRSA were 44.9% (48) and 5.6% (6), respectively, among the HIV-infected individuals, and the corresponding values within the control group were 23.4% (25) and 0.9% (1). There was a significant association between HIV infection and S. aureus colonization (p < 0.001), but not MRSA colonization (p = 0.055). The main predictor of S. aureus colonization in both study groups was absence of colonization with coagulase negative staphylococcus (p < 0.001). Furthermore, the main predictor of MRSA colonization was regular hand washing with soap (p = 0.043); this was observed among HIV-infected individuals but not the control group. The proportion of S. aureus isolates that were multidrug resistant was 62.3% (33/53) in the HIV-infected group and 80% (20/25) in the control group (p = 0.192).

CONCLUSIONS

HIV infection is a risk factor for nasal colonization of S. aureus among children in Accra but may not be for MRSA. Both the HIV-infected and uninfected children are reservoirs of multidrug resistant S. aureus. Demographic, household and clinical features appear to have little or no relationship with S. aureus and MRSA colonization in the study children.

Complement 5a Receptor Polymorphisms Are Associated With Panton-Valentine Leukocidin-positive Staphylococcus aureus Colonization in African Pygmies

Panton-Valentine leukocidin (PVL) is common in African Staphylococcus aureus and can be associated with skin and soft tissue infection. PVL-positive S. aureus colonization is associated with a variant of complement receptor 5a, the cellular target of the lukS PVL subunit.

Nasal Carriage Rate, Antimicrobial Susceptibility Pattern, and Associated Factors of Staphylococcus aureus with Special Emphasis on MRSA among Urban and Rural Elementary School Children in Gondar, Northwest Ethiopia: A Comparative Cross-Sectional Study

INTRODUCTION

Staphylococcus aureus is a Gram-positive, catalase-positive, and coagulase-positive bacterial species commonly found on the skin and in the nose of most healthy individuals. The anterior nares of nose are the most frequent carriage sites for S. aureus in both adults and children. Methicillin resistance among S. aureus isolates has steadily increased worldwide.

OBJECTIVE

The main objective of this study was to determine nasal carriage rate, antimicrobial susceptibility pattern, and associated risk factors of Staphylococcus aureus with special emphasis on MRSA among urban and rural elementary school children in Gondar, Northwest Ethiopia.

METHOD

A community based comparative cross-sectional study was conducted on 622 urban and rural elementary school children in Gondar from January 1st to March 30th, 2018. Data was collected using a questionnaire and nasal swab samples were collected by sterile cotton tip swab moistened with sterile normal saline. Collected samples were inoculated on mannitol salt agar and incubated aerobically at 37°C for 24 hrs. S. aureus was confirmed by observing colony characteristics and biochemical tests. MRSA was detected using cefoxitin disc by Modified Kirby-Bauer disk diffusion technique. Finally data was entered, cleared, and checked using Epi-info version 7 and exported to SPSS version 20 for analysis. Odds ratio and logistic regression were used for statistical association. P-value ≤ 0.05 at 95% CI was considered for statistical association.

RESULT

Of the 622 school children, the overall prevalence of S. aureus was 143/622 (23%). Of them, 14/143 (9.79%) were MRSA. The carriage rate in urban schools was 83/622 (13.3%) whereas it was 60/622 (9.6%) in rural schools. The prevalence of MRSA among urban schools, 9.1%, was higher than their urban counterparts, 0.7%. Gentamycin, clindamycin, and ciprofloxacin were the most effective whereas penicillin and tetracycline were resistant. Children's fathers' educational status and number of children in class room were significantly associated with S. aureus but only living in urban of children significantly associated with MRSA.

CONCLUSION

This study showed high prevalence of S. aureus and MRSA, 143/622 (23%) and 14/143 (9.79%), respectively. So, decolonization of nasal carriers of MRSA and reducing the number of students per classroom should be addressed. Moreover, regular large scale survey should be conducted to assess the burden and intervene accordingly.

Survey of Staphylococcus aureus in a general pediatric population and focus on isolates with three clinically relevant toxin-encoding genes

BACKGROUND

In children, surveys on Staphylococcus aureus have focused on specific infections, situations or strains but no study has so far given an overview on S. aureus isolation without any selection. Here, we describe the overall bacteriological and clinical characteristics of S. aureus isolation in children, with a special focus on isolates harbouring tst, sea, and/or luk-PV genes, respectively, encoding the three clinically relevant toxins: toxic shock syndrome toxin-1, enterotoxin A and Panton-Valentine leukocidin.

METHODS

Data associated with S. aureus isolation were reviewed: isolation site, infection status, tst, sea and luk-PV genes, antimicrobial susceptibility pattern, agr typing.

RESULTS

Three hundred and seventy-seven isolates retrieved from 328 children during S. aureus infection (55.2%) or colonisation (44.8%) were included. tst, sea and luk-PV genes were amplified in 14.3, 9.5 and 5.8% of the isolates, respectively. These isolates were significantly more frequently retrieved during infection (69.1%) than colonisation but differences were observed according to isolation site. Methicillin-resistance was found in 7.2% of the isolates, 78% of which harboured ≥ 1 of the targeted toxin-encoding genes.

CONCLUSIONS

This first comprehensive study of S. aureus in children showed S. aureus to be mainly retrieved during infection and a high rate of colonisation, not limited to the nasopharynx. Predominant infections were skin and soft tissue infections where tst was most frequently detected. luk-PV was most commonly detected during bone and joint infections. Isolates harbouring targeted toxin-encoding genes were significantly associated with infections but a quarter of children were asymptomatic carriers representing a reservoir for dissemination of isolates with virulence potency.

Methicillin Resistant Staphylococcus aureus Transmission in a Ghanaian Burn Unit: The Importance of Active Surveillance in Resource-Limited Settings

Objectives:Staphylococcus aureus infections in burn patients can lead to serious complications and death. The frequency of S. aureus infection is high in low- and middle-income countries presumably due to limited resources, misuse of antibiotics and poor infection control. The objective of the present study was to apply population genomics to precisely define, for the first time, the transmission of antibiotic resistant S. aureus in a resource-limited setting in sub-Saharan Africa.

Methods:Staphylococcus aureus surveillance was performed amongst burn patients and healthcare workers during a 7-months survey within the burn unit of the Korle Bu Teaching Hospital in Ghana.

Results: Sixty-six S. aureus isolates (59 colonizing and 7 clinical) were obtained from 31 patients and 10 healthcare workers. Twenty-one of these isolates were ST250-IV methicillin-resistant S. aureus (MRSA). Notably, 25 (81%) of the 31 patients carried or were infected with S. aureus within 24 h of admission. Genome comparisons revealed six distinct S. aureus clones circulating in the burn unit, and demonstrated multiple transmission events between patients and healthcare workers. Further, the collected S. aureus isolates exhibited a wide range of genotypic resistances to antibiotics, including trimethoprim (21%), aminoglycosides (33%), oxacillin (33%), chloramphenicol (50%), tetracycline (59%) and fluoroquinolones (100%).

Conclusion: Population genomics uncovered multiple transmission events of S. aureus, especially MRSA, within the investigated burn unit. Our findings highlight lapses in infection control and prevention, and underscore the great importance of active surveillance to protect burn victims against multi-drug resistant pathogens in resource-limited settings.

Nasal methicillin-resistant Staphylococcus aureus colonization among otherwise healthy children aged between 2 months and 5 years in northern Taiwan, 2005-2010

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections have been increasingly reported worldwide and are associated with nasal colonization. In Taiwan, available data disclosed a similar trend. We conducted a study for the updated childhood nasal MRSA carriage.

METHODS

From July 2005 to December 2010, children aged between 2 months and 5 years who presented for a well-child health care visit to a medical center or from kindergarten/daycare center were invited and a nasal swab specimen was obtained for the detection of MRSA. All MRSA isolates were characterized.

RESULTS

A total of 3226 children were included and the rate of nasal MRSA carriage was 10.2%. Children aged 2-6 months and >3 years were significantly associated with MRSA carriage, while pneumococcus colonization (p = 0.033) and breastfeeding (p = 0.025) were negatively associated with MRSA carriage. Of the 330 MRSA isolates, a total of 13 pulsotypes with two major patterns (type C, 47.0% and D, 29%) were identified. Most MRSA isolates belonged to two major clones, characterized as sequence type 59 (ST59)/pulsotype C/staphylococcal cassette chromosome (SCCmec) IV/Panton-Valentine leukocidin (PVL)-negative (45.8%) and ST59/pulsotype D/SCCmec V_T/PVL-positive (22.7%). Two new clones as ST 508/SCCmec IV (9.7%) and ST573/SCCmec IV (7.3%) emerged and increased markedly since 2007.

CONCLUSION

Between 2005 and 2010, 10.2% of healthy children in northern Taiwan carried MRSA in anterior nares, with the highest carriage rate for infants aged 2-6 months. Two emerging clones, ST 508 and ST 573, were identified and the clinical significance needs further surveillance.