Distribution of Genes Encoding Resistance to Macrolides Among Staphylococci Isolated From the Nasal Cavity of Hospital Employees in Khorramabad, Iran

Determination of the Prevalence and Antimicrobial Resistance of Enterococcus faecalis and Enterococcus faecium Associated with Poultry in Four Districts in Zambia

The presence of antimicrobial-resistant Enterococci in poultry is a growing public health concern worldwide due to its potential for transmission to humans. The aim of this study was to determine the prevalence and patterns of antimicrobial resistance and to detect drug-resistant genes in Enterococcus faecalis and E. faecium in poultry from four districts in Zambia. Identification of Enterococci was conducted using phenotypic methods. Antimicrobial resistance was determined using the disc diffusion method and antimicrobial resistance genes were detected using polymerase chain reaction and gene-specific primers. The overall prevalence of Enterococci was 31.1% (153/492, 95% CI: 27.1–35.4). Enterococcus faecalis had a significantly higher prevalence at 37.9% (58/153, 95% CI: 30.3–46.1) compared with E. faecium, which had a prevalence of 10.5% (16/153, 95% CI: 6.3–16.7). Most of the E. faecalis and E. faecium isolates were resistant to tetracycline (66/74, 89.2%) and ampicillin and erythromycin (51/74, 68.9%). The majority of isolates were susceptible to vancomycin (72/74, 97.3%). The results show that poultry are a potential source of multidrug-resistant E. faecalis and E. faecium strains, which can be transmitted to humans. Resistance genes in the Enterococcus species can also be transmitted to pathogenic bacteria if they colonize the same poultry, thus threatening the safety of poultry production, leading to significant public health concerns.

Detection of Resistant and Enterotoxigenic Strains of Staphylococcus warneri Isolated from Food of Animal Origin

The topic of this work is the detection of antimicrobial resistance to Staphylococcus warneri strains and the genes encoding staphylococcal enterotoxins. It is considered a potential pathogen that can cause various—mostly inflammatory—diseases in immunosuppressed patients. The experimental part of the paper deals with the isolation of individual isolates from meat samples of Oryctolagus cuniculus, Oncorhynchus mykiss, Scomber scombrus, chicken thigh, beef thigh muscle, pork thigh muscle, and bryndza cheese. In total, 45 isolates were obtained and subjected to phenotypic (plasma coagulase activity, nuclease, pigment, hemolysis, lecithinase, and lipase production) and genotypic analyses to confirm the presence of the S. warneri species. The presence of genes encoding staphylococcal enterotoxins A (three isolates) and D (six isolates) was determined by PCR. Using the Miditech system, the minimum inhibitory concentration for various antibiotics or antibiotics combinations was determined, namely for ampicillin; ampicillin + sulbactam; oxacillin; cefoxitin; piperacillin + tazobactam; erythromycin; clindamycin; linezolid; rifampicin; gentamicin; teicoplanin; vancomycin; trimethoprim; chloramphenicol; tigecycline; moxifloxacin; ciprofloxacin; tetracycline; trimethoprim + sulfonamide; and nitrofurantoin. Resistance to ciprofloxacin and tetracycline was most common (73%). At the same time, out of a total of 45 isolates, 22% of the isolates were confirmed as multi-resistant. Isolates that showed phenotypic resistance to β-lactam antibiotics were subjected to mecA gene detection by PCR.

Resistencia a antibióticos β-lactámicos y eritromicina en bacterias de la cavidad oral

Introducción. La microbiota humana como fuente de bacterias y genes de resistencia constituyen un problema de salud pública. En este estudio se investigó la prevalencia de bacilos entéricos Gram negativos resistentes a β-lactámicos y de los Streptococcus del grupo viridans (EGV) con resistencia a eritromicina en la cavidad oral. Métodos. Se realizó un estudio descriptivo de corte transversal con 193 aislamientos de la cavidad oral sana de 178 adultos que asistieron a una Clínica Odontológica de la ciudad de Cali durante el 2018. La evaluación de la sensibilidad antimicrobiana se realizó en 59 bacilos entéricos y 134 EGV y se identificó por PCR los genes que confieren resistencia a β-lactámicos y eritromicina. El análisis estadístico se realizó mediante el empleo del paquete SPSS vs 23. Resultados. El 84,7% de los bacilos entéricos fueron multirresistentes y presentaron genes bla, siendo blaTEM-1 (49,2%) y blaVIM-2 (30,5%,) los más prevalentes. Los EGV fueron resistentes a eritromicina (38,8%) y clindamicina (28,4%). El 18,7% presentaron el fenotipo cMLSβ, 4,5% el iMLSβ y el 14,9% fueron M.  El gen ermB se detectó en los cMLSβ, (13,4%) y el gen mef  en los M (9,7%). Conclusión. En este estudio se demostró la presencia de EGV y bacilos entéricos resistentes a los antibióticos y portadores de genes de resistencia a eritromicina y genes bla en la cavidad oral sana. La presencia de estas bacterias representa un riesgo para la salud de los individuos portadores y contribuyen a la creciente epidemia de resistencia bacteriana.

Distribution of genes encoding resistance to macrolides, lincosamides, and streptogramins among methicillin-resistant Staphylococcus aureus strains isolated from burn patients

The increasing resistance to macrolide, lincosamide, and streptogramin B agents among methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem for the health community. This study aimed to investigate the prevalence of ermA, ermB, ermC, and msrA in MRSA strains isolated from burn patients in Ahvaz, southwest of Iran. A total of 76 isolates of S. aureus were collected from January to May 2017 from Taleghani Burn Hospital in Ahvaz. Among 76 S. aureus strains collected, 60 (78.9%) isolates were MRSA. The antimicrobial susceptibility testing for MRSA showed extreme high resistance rate to clarithromycin (100%) and azithromycin (100%), followed by erythromycin (98.3%). The PCR assay revealed that the frequency rates of msrA, ermA, and ermC genes were 23 (38.3%), 28 (46.7%), and 22 (36.7%), respectively. In addition, none of the MRSA isolates had the ermB gene. Because of the high prevalence of macrolide and lincosamide resistance found in MRSA isolates from infections of burn patients in Ahvaz, southwest of Iran, it is recommended that local periodic survey be performed for controlling the dissemination of antimicrobial resistance.

Differences in distribution of MLS antibiotics resistance genes in clinical isolates of staphylococci belonging to species: S. epidermidis, S. hominis, S. haemolyticus, S. simulans and S. warneri

Background

Macrolides and lincosamides are two leading types of antibiotics commonly used in therapies. The study examines the differences in resistance to these antibiotics and their molecular bases in S. epidermidis as well as in rarely isolated species of coagulase-negative staphylococci such as S. hominis, S. haemolyticus, S. warneri and S. simulans. The isolates were tested for the presence of the erm(A), erm(B), erm(C), lnu(A), msr(A), msr(B), mph(C), ere(A) and ere(B) genes. Phenotypic resistance to methicillin and mecA presence were also determined.

Results

The MLS_B resistance mechanism was phenotypically found in isolates of species included in the study. The most prevalent MLS_B resistance mechanism was observed in S. hominis, S. haemolyticus and S. epidermidis isolates mainly of the MLS_B resistance constitutive type. Macrolide, lincosamide and streptogramin B resistance genes were rarely detected in isolates individually. The erm(B), ere(A) and ere(B) genes were not found in any of the strains. The erm(A) gene was determined only in four strains of S. epidermidis and S. hominis while lnu(A) was seen in eight strains (mainly in S. hominis). The erm(C) gene was present in most of S. epidermidis strains and predominant in S. hominis and S. simulans isolates. The examined species clearly differed between one another in the repertoire of accumulated genes.

Conclusions

The presence of genes encoding the MLS_B resistance among CoNS strains demonstrates these genes’ widespread prevalence and accumulation in opportunistic pathogens that might become gene reservoir for bacteria with superior pathogenic potential.

Molecular epidemiology of methicillin-susceptible Staphylococcus aureus (MSSA) isolated from milk of cows with subclinical mastitis

Bovine mastitis has been a concern for dairy herd for decades. The adaptation capacity of one of the main species responsible for this disease, Staphylococcus aureus (S. aureus), plays a pivotal role in this issue. The aim of this study was to establish a molecular and phenotypic profile of 285 S. aureus strains isolated from milk of subclinical mastitis cows from 18 different farms in São Paulo State using spa typing, multilocus sequence typing (MLST), pulsed field gel electrophoresis (PFGE), agr cluster (I, II, III and IV) typing, PCR for genes including enterotoxins (sea, seb, sec, sed, see, seg, seh, sei), toxic shock syndrome toxin (tsst-1), and Panton-Valentine leucocidin (pvl), as well as in vitro resistance assays for 12 antibiotics. The results showed a wide variety of strains with a high toxigenic potential; concomitantly, sec, seg and seh were prevalent. In addition, we observed a predominance of the spa types t605 (ST 126, CC126) and t127 (ST1, CC1) and the unusual presence of t321 causing bovine mastitis, which has been previously reported only in swine. The most frequent ST were ST126 (70.5%) and ST1 (10.5%). Regarding PFGE, we observed four major groups and six profile patterns. The highest resistance was observed for streptomycin (9.5%), followed by tetracycline (3.5%), clindamycin (9.3%), and erythromycin (2.8%). The tsst-1 gene was detected in 36.8% of isolates and pvl was not observed. One hundred and thirty-six (47.7%) isolates possessed agr type II, followed by types III (20%) and I (8.1%), with type IV not being detected. We observed that the same spa type could result in different PFGE profiles, so the exclusive use of spa type sequences can lead to incorrect interpretations regarding the spread of clones in an epidemiological context.

Phenotypic and genotypic characterization of macrolide resistance among Staphylococcus aureus isolates in Isfahan, Iran

BACKGROUND AND OBJECTIVES

Macrolide, lincosamide and streptogramin B (MLS _B) are noteworthy antibiotics for the treatment of Staphylococcus aureus infections. The purpose of this study, was to determine the phenotypic and genotypic characterization of macrolide resistance, among S. aureus, isolated from clinical samples and nasal swabs.

MATERIALS AND METHODS

Totally, 162 non-duplicate S. aureus isolates were collected from clinical samples and nasal swabs, from patients and healthcare workers (HCWs), between March 2016 and September 2016, at four teaching hospitals in Isfahan. The antibiotic resistance profile was determined using disk diffusion test and the presence of resistance genes was detected, using PCR.

RESULTS

Of 162 S. aureus isolates, 43.8% (71/162) and 34% (55/162) isolates were erythromycin-resistant and methicillin-resistant S. aureus (MRSA), respectively. The prevalence of constitutive MLS _B (cMLS _B), inducible MLS _B (iMLS _B), macrolide-streptogramin B-resistant (MS _B) and lincosamide-streptogramin-A resistance (LS _A) phenotype was 32%, 6%, 6% and 2%, respectively. The most common erythromycin resistance genes, in S. aureus isolates were ermC (35.2%), followed by ermA (20.4%) and msrA (17.3%). Meanwhile, msrA was detected in 43.6% of MRSA isolates. The frequency of coexistence of ermA+ermC+msrA, in S. aureus isolates was 7% and it was only detected in MRSA isolates.

CONCLUSION

In the current study, cMLS _B phenotype was the most common erythromycin resistance pattern and ermC was the most prevalent gene in erythromycin-resistant isolates. The results revealed that the various mechanisms of erythromycin resistance are expanding in Isfahan.

Prevalence of Genotypes That Determine Resistance of Staphylococci to Macrolides and Lincosamides in Serbia

Macrolides, lincosamides, and streptogramins (MLS) resistance genes are responsible for resistance to these antibiotics in Staphylococcus infections. The purpose of the study was to analyze the distribution of the MLS resistance genes in community- and hospital-acquired Staphylococcus isolates. The MLS resistance phenotypes [constitutive resistance to macrolide–lincosamide–streptogramin B (cMLSb), inducible resistance to macrolide–lincosamide–streptogramin B (iMLSb), resistance to macrolide/macrolide–streptogramin B (M/MSb), and resistance to lincosamide–streptogramin A/streptogramin B (LSa/b)] were determined by double-disc diffusion method. The presence of the MLS resistance genes (ermA, ermB, ermC, msrA/B, lnuA, lnuB, and lsaA) were determined by end-point polymerase chain reaction in 179 isolates of staphylococci collected during 1-year period at the Center for Microbiology of Public Health Institute in Vranje. The most frequent MLS phenotype among staphylococcal isolates, both community-acquired and hospital-acquired, was iMLSb (33.4%). The second most frequent was M/MSb (17.6%) with statistically significantly higher number of hospital-acquired staphylococcal isolates (p < 0.05). MLS resistance was mostly determined by the presence of msrA/B (35.0%) and ermC (20.8%) genes. Examined phenotypes were mostly determined by the presence of one gene, especially by msrA/B (26.3%) and ermC (14.5%), but 15.6% was determined by a combination of two or more genes. M/MSb phenotype was the most frequently encoded by msrA/B (95.6%) gene, LSa/b phenotype by lnuA (56.3%) gene, and iMLSb phenotype by ermC (29.4%) and ermA (25.5%) genes. Although cMLSb phenotype was mostly determined by the presence of ermC (28.9%), combinations of two or more genes have been present too. This pattern was particularly recorded in methicillin-resistant Staphylococcus aureus (MRSA) (58.3%) and methicillin-resistant coagulase-negative staphylococci (MRCNS) (90.9%) isolates with cMLSB phenotype. The msrA/B gene and M/MSb phenotype were statistically significantly higher in hospital-acquired than community-acquired staphylococci strains (p < 0.05). There are no statistically significant differences between staphylococci harboring the rest of MLS resistance genes acquired in community and hospital settings (p > 0.05). The prevalence of iMLSb phenotypes may change over time, so it is necessary to perform periodic survey of MLS resistance phenotypes, particularly where the D-test is not performed routinely.

A brief review on the application of nanoparticle enclosed herbal medicine for the treatment of infective endocarditis

Herbal medicines have been routinely employed all over the world dated back from the ancient time and have been identified by patients and physicians for their excellent therapeutic value as they have lower adverse effects when compared with the modern medicines. Phytotherapeutics requires a scientific technique to deliver the active herbal extract in a controlled manner to avoid repeated administration and increase patient compliance. This can be reached by fabricating a novel drug delivery systems (NDDS) for herbal components. NDDSs does not only decrease the repeated dose to overcome ineffectiveness, but also help to increase potency by decreasing toxicity and elevating drug bioavailability. Nano-sized DDS of herbal drugs have a potential application for improving the activity and countering the problems related to herbal medicines. Hence, application of nanocarriers as an NDDS in the traditional herbal medicine system is important to treat more chronic diseases like infectious endocarditis.