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Background: Antimicrobial resistance poses a huge risk to human health worldwide, while Bangladesh is confronting the most severe challenge between the food supply and the huge consumption of antibiotics annually. More importantly, probiotics containing Bacillus spp. are claimed to be an alternative to antimicrobial stewardship programs. However, their antibiotic resistance remains elusive. Thus, we employed the antimicrobial susceptibility test and PCR to assess the prevalence of resistance, including multidrug resistance (MDR) and resito-genotyping of isolated Bacillus spp. Results: The phenotypic profile showed that Bacillus spp. were 100% sensitive to gentamicin (2 µg/mL), whereas lowered sensitivity to levofloxacin (67.8%, 0.5–1 µg/mL), ciprofloxacin (62.3%, 0.5–1 µg/mL), clindamycin (52.2%, 0.25–0.5 µg/mL), amoxicillin-clavulanic acid (37.6%, 0.06 µg/mL), azithromycin (33.4%, 1–2 µg/mL), tetracycline (25.6%, 2–4 µg/mL), nitrofurantoin (21.1%, 16–32 µg/mL), co-trimoxazole (19.2%, 2 µg/mL), and erythromycin (18.8%, 0.25–0.5 µg/mL). The strains were completely resistant to penicillin, amoxicillin-clavulanic acid, cefixime, ceftriaxone, vancomycin, and co-trimoxazole, and a species-specific trend was seen in both phenotypic and genotypic resistance patterns. Genotypic resistance indicated prevalence of the bla1 (71.5%), tetA (33%), erm1 (27%), blaTEM (13.1%), blaCTX-M-1/blaCTX-M-2 /sul1 (10.1%), blaSHV (9.6%), and qnrS (4.1%) genes. The β-lactamase resistance gene bla1 was found in all penicillin-resistant (MIC ≥ 32 µg/mL) Bacillus spp. One hundred ninety-one isolates (89.6%) were MDR, with 100% from diarrhea, 90.3% from food, and 88.7% from animal feed. Conclusion: Based on the MIC value and profile analysis of antibiotic resistance genes, this is the first study that Bacillus spp. antimicrobial susceptibilities have been identified in Bangladesh, and our study will shed light on the adverse effects of feed-borne Bacillus spp. emerging from animal feed to the food chain. A comprehensive investigation is urgently needed by policymakers on tolerance limits and harmful effects in the animal industry. [ABSTRACT FROM AUTHOR]

Background: Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, Streptococcus pneumoniae and Staphylococcus aureus are major bacterial causes of lower respiratory tract infections (LRTIs) globally, leading to substantial morbidity and mortality. The rapid increase of antimicrobial resistance (AMR) in these pathogens poses significant challenges for their effective antibiotic therapy. In low-resourced settings, patients with LRTIs are prescribed antibiotics empirically while awaiting several days for culture results. Rapid pathogen and AMR gene detection could prompt optimal antibiotic use and improve outcomes. Methods: Here, we developed multiplex quantitative real-time PCR using EvaGreen dye and melting curve analysis to rapidly identify six major pathogens and fourteen AMR genes directly from respiratory samples. The reproducibility, linearity, limit of detection (LOD) of real-time PCR assays for pathogen detection were evaluated using DNA control mixes and spiked tracheal aspirate. The performance of RT-PCR assays was subsequently compared with the gold standard, conventional culture on 50 tracheal aspirate and sputum specimens of ICU patients. Results: The sensitivity of RT-PCR assays was 100% for K. pneumoniae, A. baumannii, P. aeruginosa, E. coli and 63.6% for S. aureus and the specificity ranged from 87.5% to 97.6%. The kappa correlation values of all pathogens between the two methods varied from 0.63 to 0.95. The limit of detection of target bacteria was 1600 CFU/ml. The quantitative results from the PCR assays demonstrated 100% concordance with quantitative culture of tracheal aspirates. Compared to culture, PCR assays exhibited higher sensitivity in detecting mixed infections and S. pneumoniae. There was a high level of concordance between the detection of AMR gene and AMR phenotype in single infections. Conclusions: Our multiplex quantitative RT-PCR assays are fast and simple, but sensitive and specific in detecting six bacterial pathogens of LRTIs and their antimicrobial resistance genes and should be further evaluated for clinical utility. [ABSTRACT FROM AUTHOR]

Background: Macrolide antibiotics have been extensively used for the treatment of Staphylococcus aureus infections. However, the emergence of macrolide-resistant strains of S. aureus has become a major concern for public health. The molecular mechanisms underlying macrolide resistance in S. aureus are complex and diverse, involving both target site modification and efflux pump systems. In this study, we aim to overcome the molecular diversity of macrolide resistance mechanisms in S. aureus by identifying common molecular targets that could be exploited for the development of novel therapeutics. Methods: About 300 Staphylococcus aureus different isolates were recovered and purified from 921 clinical specimen including urine (88), blood (156), sputum (264), nasal swabs (168), pus (181) and bone (39) collected from different departments in Tanta University Hospital. Macrolide resistant isolates were detected and tested for Multi Drug Resistant (MDR). Gel electrophoresis was performed after the D test and PCR reaction for erm(A), (B), (C), msr(A), and mph(C) genes. Finally, we tried different combinations of Erythromycin or Azithromycin antibiotics with either vitamin K3 or vitamin C. Results: Macrolide resistance S. aureus isolates exhibited 7 major resistance patterns according to number of resistance markers and each pattern included sub patterns or subgroups. The PCR amplified products of different erm genes; analysis recorded different phenotypes of the Staphylococcus aureus isolates according to their different genotypes. In addition, our new tested combinations of Erythromycin and vitamin C, Erythromycin, and vitamin K3, Azithromycin and vitamin C and Azithromycin and vitamin K3 showed significant antibacterial effect when using every antibiotic alone. Our findings provide new insights into the molecular mechanisms of macrolide resistance in S. aureus and offer potential strategies for the development of novel protocols to overcome this emerging public health threat. [ABSTRACT FROM AUTHOR]

Background: Streptococcus pneumoniae remains a leading cause of morbidity and mortality worldwide. In this study, we sought to analyze serotype distributions, antibiotic resistance, and genetic relationships of 106 clinical invasive pneumococcal isolates recovered in Tunisia between 2012 and 2018, prior to the routine use of pneumococcal conjugate vaccines (PCV). Methods: We used multiplex PCR, the disk diffusion method and/or E-test, and multi-locus sequence typing (MLST). Results: The most frequent serotypes were 14 (17%), 19F (14.2%), and 3 (11.3%). Of the 106 S. pneumoniae isolates, 67.9% were penicillin non-susceptible (29.4% were resistant), 45.3% were amoxicillin non-susceptible (17% were resistant), and 16% were cefotaxime non-susceptible. For antibiotics other than β-lactams, resistance rates to erythromycin, tetracycline, cotrimoxazole, and chloramphenicol were 62.3, 33, 22.6, and 4.7%, respectively. Two isolates were non-susceptible to levofloxacin. Among 66 erythromycin-resistant pneumococci, 77.3% exhibited the cMLSB phenotype, and 87.9% carried ermB gene. All tetracycline-resistant strains harbored the tetM gene. The potential coverage by 7-, 10-, and 13-valent pneumococcal conjugate vaccines were 55.7, 57.5, and 81.1%, respectively. A multilocus sequence typing analysis revealed great diversity. Fifty different sequence types (STs) were identified. These STs were assigned to 10 clonal complexes and 32 singletons. The most common STs were 179, 2918, 386, and 3772 – related mainly to 19F, 14, 6B/C, and 19A serotypes, respectively. Conclusions: This study demonstrated that the majority of the serotypes of invasive pneumococci in the Tunisian population were 14, 19F, and 3. Moreover, we noted a high degree of genetic diversity among invasive S. pneumoniae isolates. The highest proportions of antibiotic non-susceptible isolates were for penicillin, erythromycin, and tetracycline. Further molecular characteristics are required to monitor the genetic variations and to follow the emergence of resistant pneumococci for the post-vaccination era in Tunisia. [ABSTRACT FROM AUTHOR]

Background: The information on antibiotic resistance and molecular features of Group B Streptococcus (GBS) are essential for epidemiological purposes as well as vaccine development. Therefore, we aimed to assess the antimicrobial resistance profiles and molecular characteristics of GBS isolates in Isfahan, Iran. A total number of 72 colonizing and invasive GBS were collected from pregnant and non-pregnant women. The GBS isolates were analyzed for resistance profiles, capsular genotyping, and detection of PI-1, PI-2a, PI-2b, hvgA, ermB, ermTR, lnuB and, mefA genes. Besides, erythromycin-resistant strains were subjected to multilocus sequence typing (MLST). Results: The prevalence of colonizing and invasive GBS were 11 and 0.05%, respectively. The frequency of capsular serotypes was as follows: III (26.3%), Ia (20.83%), Ib and V (each 15.2%), IV (9.7%), II (8.3%), VII (2.7%), and VI (1.3%). Overall frequencies of PIs were as follows: PI-1, 37.5%, PI-1 + PI-2a, 30.5%, PI-1 + PI-2b, 29.1% and PI-2b, 2.7%. Two maternal colonizing GBS (2.6%) were hvgA positive and were belonged to ST-17/CPS-III/PI-1 + PI-2b lineage. Among 30(41.6%) erythromycin resistant GBS, 21 isolates (70%) harbored ermB gene, followed by ermTR (23.3%) and mefA (10%). One clindamycin-resistant isolate harbored the lnuB gene. MLST analysis revealed the following five clonal complexes (CCs) and nine STs: (CC-19/ST-335, ST-19, and ST-197), (CC-12/ST-43, ST-12), (CC-23/ST-163, ST-23), (CC-17/ST-17) and (CC-4/ST-16). Conclusion: The study shows an alarmingly high prevalence of erythromycin-resistant GBS in Iran. In addition, we report dissemination of ST-335/CPS-III clone associated with tetracycline and erythromycin resistance in our region. The distribution of capsular and pilus genotypes varies between invasive and colonizing GBS that could be helpful for vaccine development. [ABSTRACT FROM AUTHOR]

Background: Despite the employment of sanitary regimes, contact transmission of the aetiological agents of hospital infections is still exceedingly common. The issue of microbe transmission becomes particularly important when facing multidrug-resistant microorganisms such as methicillin-resistant staphylococci. In the case of deficiencies in cleaning and disinfection procedures, hospital equipment made of copper alloys can play an important role, complementing traditional hospital hygiene procedures. The objective of this study was to characterize staphylococcal strains isolated from touch surfaces in Polish hospital wards in terms of their drug resistance, ability to form biofilm and susceptibility to antimicrobial activity of copper alloys. Methods: The materials for the study were 95 staphylococcal strains isolated from touch surfaces in 13 different hospital wards from Małopolska province (the south of Poland). Phenotypic and genotypic antibiotic resistance were checked for erythromycin, clindamycin, gentamycin, ciprofloxacin, trimethoprim/sulfamethoxazole and mupirocin. Biofilm formation ability for the tested strains was checked with the use of culture on Congo red agar. Susceptibility to copper, tin bronze, brass and new silver was tested using a modification of the Japanese standard. Results: Over 67% of the analysed staphylococcal strains were methicillin-resistant (MR). Four strains were resistant to all of the tested antibiotics, and 14 were resistant to all except mupirocin. Strains classified as MR had significantly increased resistance to the remaining antibiotic groups. About one-third of the analysed strains revealed biofilm-forming ability. Among the majority of species, biofilm-forming and non-biofilm-forming strains were distributed evenly; in the case of S. haemolyticus only, negative strains accounted for 92.8%. Susceptibility to copper alloys was different between strains and rather lower than in the case of the SA strain selected for comparison. Conclusions: Coagulase-negative staphylococci, the most commonly isolated in Polish hospital wards, should not be neglected as an infection risk factor due their high antibiotic resistance. Our experiments confirmed that touch surfaces made of copper alloys may play an important role in eliminating bacteria from the hospital environment. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the safety and probiotic potential characteristics of ten Lactobacillus spp. strains ( Lactobacillus fermentum SJRP30, Lactobacillus casei SJRP37, SJRP66, SJRP141, SJRP145, SJRP146, and SJRP169, and Lactobacillus delbrueckii subsp. bulgaricus SJRP50, SJRP76, and SJRP149) that had previously been isolated from water buffalo mozzarella cheese. The safety of the strains was analyzed based on mucin degradation, hemolytic activity, resistance to antibiotics and the presence of genes encoding virulence factors. The in vitro tests concerning probiotic potential included survival under simulated gastrointestinal (GI) tract conditions, intestinal epithelial cell adhesion, the presence of genes encoding adhesion, aggregation and colonization factors, antimicrobial activity, and the production of the β-galactosidase enzyme. Although all strains presented resistance to several antibiotics, the resistance was limited to antibiotics to which the strains had intrinsic resistance. Furthermore, the strains presented a limited spread of genes encoding virulence factors and resistance to antibiotics, and none of the strains presented hemolytic or mucin degradation activity. The L. delbrueckii subsp. bulgaricus strains showed the lowest survival rate after exposure to simulated GI tract conditions, whereas all of the L. casei and L. fermentum strains showed good survivability. None of the tested lactobacilli strains presented bile salt hydrolase (BSH) activity, and only L. casei SJRP145 did not produce the β-galactosidase enzyme. The strains showed varied levels of adhesion to Caco-2 cells. None of the cell-free supernatants inhibited the growth of pathogenic target microorganisms. Overall, L. fermentum SJRP30 and L. casei SJRP145 and SJRP146 were revealed to be safe and to possess similar or superior probiotic characteristics compared to the reference strain L. rhamnosus GG (ATCC 53103). [ABSTRACT FROM AUTHOR]

Background: Quinupristin/dalfopristin (Q/D) is a valuable alternative antibiotic to vancomycin for the treatment of multi-drug resistant Enterococcus faecium infections. However, resistance to Q/D in E. faecium clinical isolates and nosocomial dissemination of Q/D-resistant E. faecium have been reported in several countries and should be of concern. Results: From January 2012 to December 2015, 911 E. faecium clinical isolates were isolated from various specimens of inpatients at the first Affiliated Hospital of Wenzhou Medical University located in Wenzhou, east China. Of 911 E. faecium clinical isolates, 9 (1.0 %, 9/911) were resistant to Q/D, with the Q/D MIC values of 64 mg/L(1), 32 mg/L(1), 16 mg/L(3), 8 mg/L(1) and 4 mg/L(3) determined by broth microdilution. All Q/D-resistant isolates were susceptible to vancomycin, tigecycline and teicoplanin but resistant to penicillin, ampicillin and erythromycin. vatE was only found in one Q/D-resistant E. faecium isolate while vatD was not detected in any of the isolates tested. 8 of 9 Q/D-resistant E. faecium isolates were found be positive for both ermB and msrC. The combinations of Q/D resistance determinants were ermB-msrC (7 isolates) and ermB-msrC-vatE (one isolate). ST78, ST761, ST94, ST21 and ST323 accounted for 4, 2, 1, 1 and 1 isolate, respectively, among which ST78 was the prevalent ST. Conclusion: Q/D-resistant E. faecium clinical isolates were first described in China. Carriage of vatE, ermB and msrC was responsible for Q/D resistance. [ABSTRACT FROM AUTHOR]

In this study the occurrence of antibiotic resistance (AR) traits was evaluated in 184 lactic acid bacteria (LAB) strains belonging to the species Lactobacillus casei/ paracasei/ rhamnosus and isolated from various sources. The strains were tested for resistance at the cut-off values fixed by the European Food Safety Authority (EFSA) for the antibiotics ampicillin, chloramphenicol, clindamycin, gentamicin, erythromycin, kanamycin, streptomycin and tetracycline, in order to distinguish resistant from susceptible strains. The strains that were not inhibited at the cut-off concentrations for one or more antibiotics, namely 27 L. paracasei and 50 L. rhamnosus strains, were further examined for minimum inhibitory concentration (MIC) and presence of acquired genes encoding resistance to the specific antibiotics by PCR assays. A minority of these strains exhibited MIC values that indicated a potentially acquired AR for ampicillin (one L. paracasei strain), clindamycin (two L. paracasei and one L. rhamnosus strains), gentamicin (two L. rhamnosus strains) and tetracycline (two L. paracasei strains and one L. rhamnosus strain); however, the genetic determinants responsible for resistance could not be identified. This study highlighted a low frequency of AR phenotypes and the absence of the most frequently acquired AR genes in the L. casei/ paracasei/ rhamnosus strains examined, thus evidencing a low risk related to AR dissemination by these bacteria. [ABSTRACT FROM AUTHOR]

Background: This study was undertaken to determine the susceptibility profile and the mechanism of antibiotic resistance in Group B streptococcus (GBS) isolates detected in vaginal and rectal swabs from pregnant women attending Dr George Mukhari Academic Hospital, a University Teaching Hospital in Pretoria, South Africa. Methods: The samples were collected over an 11-month period, cultured on selective media (colistin and nalidixic acid agar and Todd-Hewitt broth), and GBS positively identified by using different morphological and biochemical tests. The susceptibility testing was done using the Kirby-Bauer and E test methods according to CLSI guidelines 2012. The D test method was used for the detection of inducible clindamycin resistance. Multiplex PCR with specific primers was used to detect different genes coding for resistance. Results: Out of 413 samples collected, 128 (30.9 %) were positive with GBS. The susceptibility testing revealed that 100 % of isolates were sensitive to penicillin, ampicillin, vancomycin and high level gentamicin. Erythromycin and clindamycin resistance was 21.1 and 17.2 %, respectively, in which 69 % had harboured constitutive macrolide, lincosamide and streptogramin B (MLSB), 17.4 % had inducible MLSB. The M and L phenotypes were present in 6.8 % each. The methylation of target encoded by ermB genes was the commonest mechanism of resistance observed in 55 % of isolates, 38 % of isolates had both ermB and linB genes and efflux pump mediated by mefA genes was also distributed among the isolates. Conclusions: The study reaffirmed the appropriateness of penicillin as the antibiotic of choice for treating GBS infection. However it identified the challenges of resistance to macrolides and lincosamides used as alternative drugs for individuals allergic to penicillin. More GBS treatment options for penicillin allergic patients need to be researched on. [ABSTRACT FROM AUTHOR]

Background: There are limited data available on macrolide-lincosamide-streptogramin (MLS) resistance of Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CoNS) from bovine milk in China. To address this knowledge gap, MLS resistance was determined in 121 S. aureus and 97 CoNS isolates. Minimum inhibitory concentrations (MICs) of MLS antibiotics were determined by an agar dilution method, while differentiation of MLS phenotypes was performed by a double-disc diffusion test. MLS resistance genotypes were determined by PCR for corresponding resistance genes. Results: Forty (33.1 %) S. aureus and 65 (67.0 %) CoNS were resistant to erythromycin, whereas all 218 isolates were susceptible to quinupristin/dalfopristin. Among 40 erythromycin-resistant (ER-R) S. aureus and 65 ER-R CoNS isolates, 38 S. aureus and 40 CoNS isolates exhibited the inducible MLS (iMLS) resistance phenotype and 2 S. aureus and 20 CoNS isolates expressed the constitutive MLS resistance (cMLS) phenotype. At the same time, 5 CoNS isolates exhibited resistance to erythromycin but susceptibility to clindamycin (the MS phenotype). An inactivating enzyme gene lnu(A), methylase genes erm(C) and erm(B), efflux genes msr(A)/msr(B), a phosphotransferase gene mph(C), an esterase gene ere(A) and the streptogramin resistance determinant vga(A) were detected individually or in combinations. Among them, genes lnu(A), erm(C) and mph(C) predominated. The ereA gene was detected for the first time in staphylococci of bovine milk origin. Resistance genes also existed in erythromycin-susceptible isolates. Conclusions: Our study demonstrated a high level of resistance to MLS antibiotics in staphylococci from bovine mastitic milk, especially with a high rate of the iMLS phenotype in S. aureus isolates. These data suggest that MLS antibiotics should be used judiciously to treat or prevent bovine mastitis caused by staphylococci. [ABSTRACT FROM AUTHOR]

Background: In the last decade, the Streptococcus pneumoniae population has changed, mainly due to the abuse of antibiotics. The aim of this study was to determine the genetic structure of 144 S. pneumonia serotype 14 isolates collected from children with acute respiratory infections during 1997-2012 in China. Methods: All isolated pneumococci were tested for their sensitivity to 11 kinds of antibiotics with the E-test method or disc diffusion. The macrolides resistance genes ermB and mefA, as well as the sulfamethoxazole-trimethoprim resistance gene dihydrofolate reductase (DHFR) were detected by polymerase chain reaction (PCR). The sequence types (STs) were analyzed with multilocus sequence typing (MLST). Results: From 1997 to 2012, the percentage of serotype 14 S. pneumonia isolates in the whole isolates increased. All of the 144 serotype 14 S. pneumonia isolates were susceptible to amoxicillin-clavulanic acid, vancomycin and levofloxacin. No penicillin resistant isolate was found, and the intermediate rate was as low as 0.7 %. Erythromycin resistance was confirmed among 143 isolates. The ermB gene was determined in all erythromycin resistant isolates, and the mefA gene was positive additionally in 13 of them. The non-susceptibility rate to the tested cephalosporins increased from 1997-2012. All trimethoprim-resistant isolates contained the Ile100-Leu mutation. Overall, 30 STs were identified, among which ST876 was the most prevalent, followed by ST875. During the study period, the percentage of CC876 increased from 0 % in 1997-2000 to 96.4 % in 2010-2012, whereas CC875 decreased from 84.2 to 0 %. CC876 showed higher non-susceptibility rates to β-lactam antibiotics than CC875. Conclusion: The percentage of serotype 14 S. pneumonia isolates increased over time in China. The increase of resistance to β-lactam antibiotics in this serotype isolates was associated with the spread of CC876. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to investigate the prevalence and characterization of Listeria species and Listeria monocytogenes isolated from raw fish and open-air fish market environments. Eight hundred and sixty two samples including raw fish and fish market environments (samples from workers' hands, workers' knives, containers and work surface) were collected from the open-air fish markets in the Northern region of Iran. Results: Listeria spp. was isolated from 104/488 (21.3 %) raw fish and 29/374 (7.8 %) of samples from open-air fish market environment. The isolates of Listeria spp. included L. innocua (35.3 %), L. monocytogenes (32.3 %), L. seeligeri (18 %), and L. ivanovii (14.3 %). Of the 43 L. monocytogenes isolates, 31 (72.1 %), 10 (23.3 %) and 2 (4.7 %) belonged to serovars 1/2a, 4b, and 1/2b, respectively. The inlA, inlB, inlC, inlJ, actA, hlyA, iap, plcA, and prfA virulence-associated genes were detected in almost all of the L. monocytogenes isolates. The Listeria spp. isolates showed high resistance against tetracycline (23.3 %), penicillin G, and cephalothin (each 16.5 %). Besides, we observed significant resistance level to tetracycline (27.9 %), ampicillin (20.9 %), cephalothin, penicillin G, and streptomycin (each 16.3 %) in the L. monocytogenes isolates. All of the isolates were susceptible to cefotaxime, gentamicin, kanamycin, and pefloxacin. We found that tetM (25.6 %), tetA (23.3 %), ampC (14 %), and penA (11.6 %) were the most prevalent antibiotic resistance genes in the L. monocytogenes isolates. Conclusions: Recovery of potentially pathogenic L. monocytogenes from raw fish and environment of open-air fish market samples in this study is a convincing evidence for the zoonotic potential of listeriosis. [ABSTRACT FROM AUTHOR]

Antimicrobial agents exert a selection pressure not only on pathogenic, but also on commensal bacteria of the intestinal tract of humans and animals. The aim of this work was to determine the occurrence of different enterococcal species and to analyse the prevalence of antimicrobial resistance and the mechanisms implicated, as well as the genetic diversity in enterococci recovered from faecal samples of food-producing animals (poultry, beef and sheep) in Tunisia. Antimicrobial resistance and the mechanisms implicated were studied in 87 enterococci recovered from 96 faecal samples from animals of Tunisian farms. Enterococcus faecium was the most prevalent species detected (46 %), followed by E. hirae (33.5 %). High percentages of resistance to erythromycin and tetracycline were found among our isolates, and lower percentages to aminoglycosides and ciprofloxacin were identified. Most of the tetracycline-resistant isolates carried the tet(M) and/or tet(L) genes. The erm(B) gene was detected in all erythromycin-resistant isolates. The ant(6)-Ia, aph(3′)-Ia and aac(6′)- aph(2″) genes were detected in nine aminoglycoside-resistant isolates. Of our isolates, 11.5 % carried the gelE gene and exhibited gelatinase acitivity. The esp gene was detected in 10 % of our isolates and the hyl gene was not present in any isolate. The predominant species ( E. faecium and E. hirae) showed a high genetic diversity by repetitive extragenic palindromic (REP)-PCR. Food animals might play a role in the spread through the food chain of enterococci with virulence and resistance traits to humans. [ABSTRACT FROM AUTHOR]

Background: Our aim was to determine and characterize S. aureus (SA) isolated from infections in newborns for antibiotic resistance, virulence factors, genotypes, epidemiology and antibiotic consumption. Methods: Prospective surveillance of infections was conducted. Data about antibiotic treatment were analyzed. Antimicrobial susceptibility was assessed. PCR amplification was used to detect resistance and virulence genes. Typing methods such as PFGE, spa-typing and SCCmec were used. Results: SA was found to be associated with 6.5% of infections. Methicillin-Resistant Staphylococcus aureus accounted for 32.8% of SA-infections. An incidence of MRSA-infections was 1.1/1000 newborns. MRSA-infections were diagnosed significantly earlier than MSSA-infections in these newborns (14th day vs. 23rd day (p = 0.0194)). MRSA-infections increased the risk of newborn's death. Antibiotic consumption in both group was similar, but a high level of glycopeptides-usage for MSSA infections was observed. In the MRSA group, more strains were resistant to erythromycin, clindamycin, gentamicin and amikacin than in the MSSA group. Hla gene was present in 93.9% of strains, and seg and sei in 65.3% of strains, respectively. One dominant clone was found among the 14 MRSA isolates. Fifteen strains belonging to SCCmec type IV were spa-t015 and one strain belonging to SCCmec type V was spa-t011. Conclusions: Results obtained in the study point at specific epidemiological situation in Polish NICU (more detailed studies are recommended). High usage of glycopeptides in the MSSA infections treatment indicates the necessity of antimicrobial stewardship improvement and introducing molecular screening for early identification of infections. [ABSTRACT FROM AUTHOR]

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important nosocomial pathogens and is also emerging in Turkish hospitals. The aim of this study was to determine the antimicrobial susceptibility profiles of MRSA isolated from Turkish hospitals. Materials and methods A total of 397 MRSA strains isolated from 12 hospitals in Turkey were included to present study. Antimicrobial susceptibilities were tested using agar dilution. Presence of ermA, ermB, ermC, msrA, tetM, tetK, linA and aac-aph genes were studied by PCR. Results All strains were susceptible to vancomycin and linezolid. The susceptibility rates for fusidic acid, lincomycin, erythromycin, tetracyclin, gentamycin, kanamycin, and, ciprofloxacin were 91.9%, 41.1%, 27.2%, 11.8%, 8.5%, 8.3% and 6.8%, respectively. Lincomycin inactivation was positive for 3 isolates. Of 225 erythromycin resistant isolates 48 had ermA, 20 had ermC, and 128 had ermA-C. PCR was negative for 15 strains. Of 3 isolates with lincomycin inactivation one had linA and msrA. Of 358 gentamycin resistant isolates 334 had aac-aph and 24 were negatives. Among 350 tetracyclin resistant isolates 314 had tetM. Of 36 tetM negative isolates 10 had tetK. Conclusion MRSA isolates from Turkish hospitals were multiresistant to antimicrobials. Quinolone and gentamycin resistance levels were high and macrolide and lincosamide resistance were relatively low. Susceptibility rates for fusidic asid were high. Linezolide and vancomycin resistance are not emerged. The most common resistance genes were ermA, tetM and aacaph. Evolution of antimicrobial susceptibilities and resistance genes profiles of MRSA isolates should be surveyed at regional and national level for accurate treatment of patients and to control dissemination of resistance genes. [ABSTRACT FROM AUTHOR]

Background Group B Streptococcus (GBS) remains a major cause of neonatal sepsis and is also associated with invasive and noninvasive infections in pregnant women and non-pregnant adults, elderly and patients with underlying medical conditions. Ten capsular serotypes have been recognized, and determination of their distribution within a specific population or geographical region is important as they are major targets for the development of vaccine strategies. We have evaluated the characteristics of GBS isolates recovered from individuals with infections or colonization by this microorganism, living in different geographic regions of Brazil. Methods A total of 434 isolates were identified and serotyped by conventional phenotypic tests. The determination of antimicrobial susceptibility was performed by the disk diffusion method. Genes associated with resistance to erythromycin (ermA, ermB, mefA) and tetracycline (tetK, tetL, tetM, tetO) as well as virulence-associated genes (bac, bca, lmb, scpB) were investigated using PCR. Pulsed-field gel electrophoresis (PFGE) was used to examine the genetic diversity of macrolide-resistant and of a number of selected macrolide-susceptible isolates. Results Overall, serotypes Ia (27.6%), II (19.1%), Ib (18.7%) and V (13.6%) were the most predominant, followed by serotypes IV (8.1%) and III (6.7%). All the isolates were susceptible to the beta-lactam antimicrobials tested and 97% were resistant to tetracycline. Resistance to erythromycin and clindamycin were found in 4.1% and 3% of the isolates, respectively. Among the resistance genes investigated, tetM (99.3%) and tetO (1.8%) were detected among tetracycline-resistant isolates and ermA (39%) and ermB (27.6%) were found among macrolide-resistant isolates. The lmb and scpB virulence genes were detected in all isolates, while bac and bca were detected in 57 (13.1%) and 237 (54.6%) isolates, respectively. Molecular typing by PFGE showed that resistance to erythromycin was associated with a variety of clones. Conclusion These findings indicate that GBS isolates circulating in Brazil have a variety of phenotypic and genotypic characteristics, and suggest that macrolide-resistant isolates may arise by both clonal spread and independent acquisition of resistance genes. [ABSTRACT FROM AUTHOR]

Background The World Health Organization reported in 2007 that inclusion of PCV7 in national immunization programs should be seen as a priority, also encouraging countries to conduct appropriate surveillances for monitoring the impact of vaccination. These analyses should be conducted in specific geographical areas and should be aimed to evolution of invasive pneumococcal disease (IPD), by age groups, clinical presentation, and vaccine serotypes (and non-vaccine serotypes to detect possible replacement). This study aimed to monitor the evolution of IPD incidence in children <15 years requiring hospitalization in the Island of Majorca. Methods A prospective clinical surveillance of all culture and/or PCR-confirmed IPD in children <15 years was performed in all hospitals in the Island of Majorca (approximately 900,000 inhabitants) from January 2008 to December 2010. Incidence rate (IR) was calculated as cases/100000 inhabitants using children population data. Results 66 IPDs were identified: 39 (59.1%) parapneumonic pneumococcal empyema (PPE), 16 (24.2%) bacteremic pneumonia (BP), 7 (10.6%) primary bacteremia, 3 (4.5%) meningitis, and 1 (1.5%) osteomyelitis. IRs in the three-year study period were: 64.22 for children 12- < 24 months, 37.21 for those 24-59 months, 22.62 for those <12 months, and 3.98 for children >59 months. By study year, IRs were 21.25 in 2008, 19.89 in 2009 and 9.80 in 2010. The reduction found in 2010 was significant and due to significant reductions in IRs of IPDs caused by serotypes included in PCV10 and PCV13. Overall, estimated serotype coverage by conjugate vaccines was 12.1% for PCV7, 37.9% for PCV10 and 65.2% for PCV13. Of the 66 hospitalized children with IPD, 20 had received at least one dose of PCV7 (13 cases with identified serotype). None of these 13 cases was caused by PCV7 serotypes, all were caused by PCV13 serotypes and only 53.8% by PCV10 serotypes. Conclusions The results of the present study evidence the importance of expanding the number of serotypes covered by PCV, and the added value of PCV13 with respect to PCV10 and PCV7, even in an area of low prevalence of 19A as the Island of Majorca. [ABSTRACT FROM AUTHOR]

Background: Antimicrobial resistance among pneumococci has greatly increased over the past two to three decades. Resistance to tetracycline (tet(M)), chloramphenicol (cat) and macrolides (erm(B) and/or mef(A/E)) is generally conferred by acquisition of specific genes that are associated with mobile genetic elements, including those of the Tn916 and Tn5252 families. The first tetracycline-, chloramphenicol- and macrolide-resistant pneumococci were detected between 1962 and 1970; however, until now the oldest pneumococcus shown to harbour Tn916 and/or Tn5252 was isolated in 1974. In this study the genomes of 38 pneumococci isolated prior to 1974 were probed for the presence of tet(M), cat, erm(B), mef(A/E) and int (integrase) to indicate the presence of Tn916/Tn5252-like elements. Results: Two Tn916-like, tet(M)-containing, elements were identified among pneumococci dated 1967 and 1968. The former element was highly similar to that of the PMEN1 multidrug-resistant, globally-distributed pneumococcal reference strain, which was isolated in 1984. The latter element was associated with a streptococcal phage. A third, novel genetic element, designated ICESpPN1, was identified in the genome of an isolate dated 1972. ICESpPN1 contained a region of similarity to Tn5252, a region of similarity to a pneumococcal pathogenicity island and novel lantibiotic synthesis/export-associated genes. Conclusions: These data confirm the existence of pneumococcal Tn916 elements in the first decade within which pneumococcal tetracycline resistance was described. Furthermore, the discovery of ICESpPN1 demonstrates the dynamic variability of pneumococcal genetic elements and is contrasted with the evidence for Tn916 stability. [ABSTRACT FROM AUTHOR]

Background: Pneumococcal and Haemophilus influenzae type b (Hib) vaccines were introduced in our national immunisation program in April 2010. The aims of this retrospective, laboratory-based study were to determine the serotypes and antibiotic resistance of Streptococcus pneumoniae and H. influenzae isolates from middle ear fluid (MEF) collected before the introduction of immunization. Methods: S. pneumoniae (n = 128) and H. influenzae (n = 40) strains isolated from MEF of children with AOM between 1994 and 2011 were studied. MICs were determined by a microdilution assay. Serotyping of S. pneumoniae was done by Quellung method and PCR capsular typing was used for H. influenzae. Macrolide resistance genes were detected by PCR for erythromycin resistant S. pneumoniae (ERSP). DNA sequencing of ftsI gene was performed for ampicillin nonsusceptible H. influenzae. Results: The most common serotypes found among children with pneumococcal AOM were 19 F (20.3%), 6B (15.6%), and 19A (10.9%). The potential coverage rates by the PCV7, PCV10 and PCV13 of children aged < 5 years were 63.6%, 66.4% and 85.5%, respectively. Reduced susceptibility to oral penicillin was seen in 68.1%; resistance to erythromycin was 46.9%. We found erm(B) gene in 56.7% of the ERSP, mef(E) gene in 25%; 15% harbored both genes erm(B) + mef(E) and 3.3% had mutations of L4 ribosomal protein. Of the 40 H. influenzae isolates 97.5% were nontypeable. Nonsusceptibility to ampicillin occurred in 25%. Ampicillin resistance groups were: β-lactamase -positive ampicillin resistant (BLPAR) strains (10%), β-lactamase-negative ampicillin resistant (BLNAR) strains (12.5%) and β-lactamase-positive amoxicillin-clavulanate resistant (BLPACR) strains (2.5%). Among BLNAR and BLPACR most of the isolates (5/6) belonged to group II, defined by the Asn526Lys substitution. Conclusions: The levels of antibiotic resistance among S. pneumoniae and H. influenzae causing severe AOM in children are high in our settings. The existence of multidrug-resistant S. pneumoniae serotype 19A is of particular concern. The rate of BLNAR and BLPACR strains among H. influenzae isolates was 15%. [ABSTRACT FROM AUTHOR]

A total of 194 enterococcal isolates were recovered from 198 fecal samples of pigs, cattle, and sheep obtained in a Portuguese slaughterhouse. The enterococcal species most prevalent were Enterococcus faecium and E. hirae. High percentages of resistance were detected for tetracycline in pig isolates (95.7%), sheep isolates (76.7%), and cattle isolates (49%); erythromycin resistance was higher in pig isolates than in cattle or sheep isolates. Intermediate level of resistance was obtained to quinupristin/dalfopristin in all animal isolates (15.1-23.5%). High-level resistance to aminoglycosides was detected, HLR-S and -K was higher in pig isolates (44.3 and 32.9%, respectively) compared with cattle or sheep isolates, and modest percentages of HLR-G were obtained in pig and cattle isolates (7.1 and 3.9%, respectively). The aac(6`)- aph(2'), aph(3`)-IIIa, ant(6)-Ia, cat(A), erm(B), and tet(M) genes were demonstrated in most of the gentamycin-, kanamycin-, streptomycin-, chloramphenicol-, erythromycin- and tetracycline-resistant isolates, respectively. The association between the tet(M) gene and Tn 916/Tn 1545-like or Tn 5397-like transposons was detected in 30.8 and 11.2% of the isolates, respectively. Food animals could be a reservoir for antibiotic resistance genes, and slaughterhouse cross-contamination of animals carcasses may be a food safety risk. [ABSTRACT FROM AUTHOR]

The consequence of excessive use of macrolides is a high occurrence of mechanisms responsible for resistance to these drugs. Of 97 erythromycin-resistant bacterial strains gathered in the Wrocław area in Poland, 60% exhibited very high resistance, and those with the inducible MLS (macrolide-lincosamide-streptogramin B) resistance phenotype predominated. Direct genetic investigation revealed that the erm genes coding for ribosomal methylases are the most frequently occurring erythromycin resistance-determining genes. No genetic resistance determinant was detected in 13% of the erythromycin-resistant strains. The efflux mechanism occurs in strains isolated from the nasopharyngeal cavity twice as often as in those isolated from other material, where the mechanism connected with target site modification predominates. Measurements of radiolabelled antibiotic accumulation inside bacterial cells revealed that in highly resistant strains (MIC > 1024 μg/ml), an important factor responsible for the resistance is the permeability barrier at the cell wall level. This would be a hitherto unknown mechanism of resistance to erythromycin in Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Background: We sought to characterize the temporal trends in nasopharyngeal carriage of macrolide-resistant pneumococci during a period with increased heptavalent pneumococcal conjugate vaccine (PCV7) coverage in Central Greece.Methods: Streptococcus pneumoniae isolates were recovered from 2649 nasopharyngeal samples obtained from day-care center attendees in Central Greece during 2005-2009. A phenotypic and genotypic analysis of the isolates was performed, including the identification of macrolide resistance genes mef(A), subclasses mef(A) and mef(E),as well as erm(B).Results: Of the 1105 typeable S. pneumoniae isolates, 265 (24%) were macrolide-resistant; 22% in 2005, 33.3% in2006, 23.7% in 2007, and 20.5% in 2009 (P=0.398). Among these macrolide-resistant pneumococci, 28.5% possessed erm(B), 24.3% erm(B)+mef(E), 41.8% mef(E), and 5.3% mef(A). A mef gene as the sole resistance determinant was carried by 31% of macrolide-resistant isolates belonging to PCV7 serotypes and 75.8% of the non-PCV7 serotypes.Across the 4 annual surveillances, pneumococci carrying mef(A) gradually disappeared, whereas serotype 19F isolates carrying both erm(B) and mef(E) persisted without significant yearly fluctuations. Among isolates belonging to non-PCV7 serotypes, macrolide-resistance was observed in those of serotypes 6A, 19A, 10A, 15A, 15B/C, 35F, 35A,and 24F. In 2009, ie 5 years after the introduction of PCV7 in our country, 59% of macrolide-resistant pneumococci belonged to non-PCV7 serotypes.Conclusions: Across the study period, the annual frequency of macrolide-resistant isolates did not change significantly, but in 2009 a marked shift to non-PCV7 serotypes occurred. Overall, more than half of the macrolide-resistant isolates possessed erm(B) either alone or in combination with mef(E). erm(B) dominated among isolates belonging to PCV7 serotypes, but not among those of non-PCV7 serotypes. [ABSTRACT FROM AUTHOR]

The article focuses on a study which determines macrolide resistance genotypes in clinical isolates of Streptococcus pneumoniae in Lebanon. It reports that several Streptococcus pneumoniae were tested in the medical centers for antimicrobial susceptibility and underwent molecular characterization. It concludes that S. pneumoniae is through target site modification and is also mediated through efflux pumps, invasive and most pervalent.

Background: Streptococcus pneumoniae is the main pathogen that causes respiratory infections in children younger than five years. The increasing incidence of macrolide- and tetracycline-resistant pneumococci among children has been a serious problem in China for many years. The molecular characteristics of erythromycin-resistant pneumococcal isolates that were collected from pediatric patients younger than five years in Beijing in 2010 were analyzed in this study. Results: A total of 140 pneumococcal isolates were collected. The resistance rates of all isolates to erythromycin and tetracycline were 96.4% and 79.3%, respectively. Of the 135 erythromycin-resistant pneumococci, 91.1% were non-susceptible to tetracycline. In addition, 30.4% of the erythromycin-resistant isolates expressed both the ermB and mef genes, whereas 69.6% expressed the ermB gene but not the mef gene. Up to 98.5% of the resistant isolates exhibited the cMLSB phenotype, and Tn6002 was the most common transposon present in approximately 56.3% of the resistant isolates, followed by Tn2010, with a proportion of 28.9%. The dominant sequence types (STs) in all erythromycin-resistant S. pneumoniae were ST271 (11.9%), ST81 (8.9%), ST876 (8.9%), and ST320 (6.7%), whereas the prevailing serotypes were 19F (19.3%), 23F (9.6%), 14 (9.6%), 15 (8.9%), and 6A (7.4%). The 7-valent pneumococcal conjugate vaccine (PCV7) and 13-valent pneumococcal conjugate vaccine (PCV13) coverage of the erythromycin-resistant pneumococci among the children younger than five years were 45.2% and 62.2%, respectively. ST320 and serotype 19A pneumococci were common in children aged 0 to 2 years. CC271 was the most frequent clonal complex (CC), which accounts for 24.4% of all erythromycin-resistant isolates. Conclusions: The non-invasive S. pneumoniae in children younger than five years in Beijing presented high and significant resistance rates to erythromycin and tetracycline. The expressions of ermB and tetM genes were the main factors that influence pneumococcal resistance to erythromycin and tetracycline, respectively. Majority of the erythromycin-resistant non-invasive isolates exhibited the cMLSB phenotype and carried the ermB, tetM, xis, and int genes, suggesting the spread of the transposons of the Tn916 family. PCV13 provided higher serotype coverage in the childhood pneumococcal diseases caused by the erythromycin-resistant isolates better than PCV7. Further long-term surveys are required to monitor the molecular characteristics of the erythromycin-resistant S. pneumoniae in children. [ABSTRACT FROM AUTHOR]

Background: Extensive use of antibiotics as growth promoters in the livestock industry constitutes strong selection pressure for evolution and selection of antibiotic resistant bacterial strains. Unfortunately, the microbial ecology and spread of these bacteria in the agricultural, urban, and suburban environments are poorly understood. Insects such as house flies (Musca domestica) and German cockroaches (Blattella germanica) can move freely between animal waste and food and may play a significant role in the dissemination of antibiotic resistant bacteria within and between animal production farms and from farms to residential settings. Results: Enterococci from the digestive tract of house flies (n = 162), and feces of German cockroaches (n = 83) and pigs (n = 119), collected from two commercial swine farms were isolated, quantified, identified, and screened for antibiotic resistance and virulence. The majority of samples (93.7%) were positive for enterococci with concentrations 4.2 ± 0.7 × 104 CFU/house fly, 5.5 ± 1.1 × 106 CFU/g of cockroach feces, and 3.2 ± 0.8 × 105 CFU/g of pig feces. Among all the identified isolates (n = 639) Enterococcus faecalis was the most common (55.5%), followed by E. hirae (24.9%), E. faecium (12.8%), and E. casseliflavus (6.7%). E. faecalis was most prevalent in house flies and cockroaches, and E. hirae was most common in pig feces. Our data showed that multi-drug (mainly tetracycline and erythromycin) resistant enterococci were common from all three sources and frequently carried antibiotic resistance genes including tet(M) and erm(B) and Tn916/1545 transposon family. E. faecalis frequently harbored virulence factors gelE, esp, and asa1. PFGE analysis of selected E. faecalis and E. faecium isolates demonstrated that cockroaches and house flies shared some of the same enterococcal clones that were detected in the swine manure indicating that insects acquired enterococci from swine manure. Conclusions: This study shows that house flies and German cockroaches in the confined swine production environment likely serve as vectors and/or reservoirs of antibiotic resistant and potentially virulent enterococci and consequently may play an important role in animal and public health. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Tree shrew is a novel laboratory animal with specific characters for human disease researches in recent years. However, little is known about its characteristics of gut microbial community and intestinal commensal bacteria. In this study, 16S rRNA sequencing method was used to illustrate the gut microbiota structure and commensal Enterobacteriaceae bacteria were isolated to demonstrate their features. Results: The results showed Epsilonbacteraeota (30%), Proteobacteria (25%), Firmicutes (19%), Fusobacteria (13%), and Bacteroidetes (8%) were the most abundant phyla in the gut of tree shrew. Campylobacteria, Campylobacterales, Helicobacteraceae and Helicobacter were the predominant abundance for class, order, family and genus levels respectively. The alpha diversity analysis showed statistical significance (P < 0.05) for operational taxonomic units (OTUs), the richness estimates, and diversity indices for age groups of tree shrew. Beta diversity revealed the significant difference (P < 0.05) between age groups, which showed high abundance of Epsilonbacteraeota and Spirochaetes in infant group, Proteobacteria in young group, Fusobacteria in middle group, and Firmicutes in senile group. The diversity of microbial community was increased followed by the aging process of this animal. 16S rRNA gene functional prediction indicated that highly hot spots for infectious diseases, and neurodegenerative diseases in low age group of tree shrew (infant and young). The most isolated commensal Enterobacteriaceae bacteria from tree shrew were Proteus spp. (67%) and Escherichia coli (25%). Among these strains, the antibiotic resistant isolates were commonly found, and pulsed-field gel electrophoresis (PFGE) results of Proteus spp. indicated a high degree of similarity between isolates in the same age group, which was not observed for other bacteria. Conclusions: In general, this study made understandings of the gut community structure and diversity of tree shrew. [ABSTRACT FROM AUTHOR]

Background: Group B Streptococcus (GBS) is a leading cause of early-onset disease (EOD) and late-onset disease (LOD) in infants. We sought to investigate the antibiotic susceptibility profiles, resistance genes, virulence-related genes, serotype distribution and genotypic characteristics of GBS recovered from infected or colonized neonates and pregnant women in a tertiary teaching hospital in Shenzhen, China, from 2008 to 2015. Results: High resistance rates of erythromycin (66.7–100%) were detected among early-onset GBS (EOGBS), late-onset GBS (LOGBS), neonatal colonizing GBS (NCGBS) and maternal colonizing GBS (MCGBS). 89.5–100% of four groups of GBS isolates showed resistance to tetracycline. More than 90 % of erythromycin resistant isolates of EOGBS (8/8, 100%), LOGBS (16/17, 94.1%) and NCGBS (10/11, 90.9%) harbored ermB, while only 9.1–17.6% harbored mefA/E. By contrast, 55.8% (24/43) and 62.8% (27/43) of erythromycin resistant MCGBS isolates carried ermB and mefA/E genes, respectively. The tetO gene was more common in tetracycline resistant EOGBS (10/11, 90.9%), LOGBS (17/17, 100%) and NCGBS (10/11, 90.9%), compared to tetracycline resistant MCGBS (12/51, 23.5%). Additionally, the tetM gene accounted for 90.9% (10/11), 76.5% (13/17), 45.5% (5/11) and 80.4% (41/51) of four groups of isolates, respectively. Serotype III was the most predominant in EOGBS (8/12, 66.7%) and LOGBS (15/17, 88.2%), while serotype Ib accounted for 50.0% (6/12) of NCGBS, and serotype Ia and III accounted for 45.6% (26/57) and 33.3% (19/57) of MCGBS, respectively. Sequence type 17 (ST17) was the most common in EOGBS (6/12, 50%) and LOGBS (12/17, 70.6%), while ST12 was predominant in NCGBS (5/12, 41.7%), and five STs (ST19, ST23, ST12, ST103 and ST485) accounted for 66.7% (38/57) of the MCGBS. All serotype III-ST17 isolates recovered from neonates were associated with invasive infections. Conclusions: This study shows the meaningful differences in molecular mechanisms of resistance to erythromycin and tetracycline, and the prevalence of serotypes and STs among GBS recovered from neonates and pregnant women. ST17 is predominant in neonatal invasive GBS, but rare in NCGBS and MCGBS. [ABSTRACT FROM AUTHOR]

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 MLSB resistance mechanism was phenotypically found in isolates of species included in the study. The most prevalent MLSB resistance mechanism was observed in S. hominis, S. haemolyticus and S. epidermidis isolates mainly of the MLSB 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 MLSB 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. [ABSTRACT FROM AUTHOR]

Background: Solithromycin, the fourth generation of ketolides, has been demonstrated potent antibacterial effect against commonly-isolated gram-positive strains. However, Staphylococcus aureus (S. aureus) strains with a higher solithromycin MIC have already been emerged, the mechanism of which is unknown.Methods: Antimicrobial susceptibility test was performed on 266 strains of S. aureus. The antibiotic resistance phenotype of erm-positive strain was determined by D-zone test. Spontaneous mutation frequency analysis was performed to compare the risk levels for solithromycin resistance among different strains. Efflux pumps and mutational analysis of ribosomal fragments as well as erm(B) gene domains were detected. Quantitative reverse transcription polymerase chain reaction was conducted to compare the transcriptional expression of the erm gene between the constitutive macrolide-lincosamide-streptogramin B (cMLSB)- and inducible MLSB (iMLSB)-phenotypes.Results: In the erm-positive S. aureus strains, the minimum inhibitory concentration (MIC)50/90 of solithromycin (2/> 16 mg/L) was significantly higher than that in the erm-negative strains (0.125/0.25 mg/L). Of note, the MIC50 value of the strains with iMLSB (0.25 mg/L) was significantly lower than that of the strains with cMLSB (4 mg/L). A comparison among strains demonstrated that the median mutational frequency in isolates with cMLSB (> 1.2 × 10- 4) was approximately > 57-fold and > 3333-fold higher than that in iMLSB strains (2.1 × 10- 6) and in erythromycin-sensitive strains (3.6 × 10- 8), respectively. The differential antibiotic in vitro activity against strains between cMLSB and iMLSB could not be explained by efflux pump carriers or genetic mutations in the test genes. The expression of the erm genes in strains with cMLSB did not differ from that in strains with iMLSB.Conclusions: The reduced susceptibility to solithromycin by S. aureus was associated with the cMLSB resistance phenotype mediated by erm. [ABSTRACT FROM AUTHOR]

Background: Emerging antimicrobial resistance is a significant threat to human health. However, methods for rapidly diagnosing antimicrobial resistance generally require multi-day culture-based assays. Macrolide efflux gene A, mef(A), provides resistance against erythromycin and azithromycin and is known to be laterally transferred among a wide range of bacterial species.Methods: We use Recombinase Polymerase Assay (RPA) to detect the antimicrobial resistance gene mef(A) from raw lysates without nucleic acid purification. To validate these results we performed broth dilution assays to assess antimicrobial resistance to erythromycin and ampicillin (a negative control).Results: We validate the detection of mef(A) in raw lysates of Streptococcus pyogenes, S. pneumoniae, S. salivarius, and Enterococcus faecium bacterial lysates within 7-10 min of assay time. We show that detection of mef(A) accurately predicts real antimicrobial resistance assessed by traditional culture methods, and that the assay is robust to high levels of spiked-in non-specific nucleic acid contaminant. The assay was unaffected by single-nucleotide polymorphisms within divergent mef(A) gene sequences, strengthening its utility as a robust diagnostic tool.Conclusions: This finding opens the door to implementation of rapid genomic diagnostics in a clinical setting, while providing researchers a rapid, cost-effective tool to track antibiotic resistance in both pathogens and commensal strains. [ABSTRACT FROM AUTHOR]

Background: Vancomycin is still one of the most commonly used drug for treatment of severe methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin-resistant S. aureus (VRSA) strains are a serious danger for public health. This study aimed to characterize healthcare-associated MRSA (HA-MRSA) strains, resistant to at least one of glycopeptide antibiotics: vancomycin (VRSA) and/or teicoplanin (TRSA), isolated at three Warsaw hospitals over a period of 17-years (1991–2007). Methods: Among 600 HA-MRSA strains, isolated from patients with symptomatic infections, 47 were subjected to detailed analysis. In the study, mechanisms behind VRSA phenotypes were determined (E-tests, GRD-test, agar-dilution method and vanA/B detection). Characteristics of selected isolates on molecular level: i) by detection of resistance genes ermA/ermB/ermC, msrA/msrB, linA/linA’, aacA-aphD, aadD, aph(3”)-IIIa; ii) SCCmec-typing and iii) MLST-typing was done. Results: In general population of studied strains, 11/47 (23.4%) were VRSA and 36/47 (76.6%) were resistant only to teicoplanin. All isolates exhibited van-independent mechanisms of resistance. Over 80% of isolates belonged to clonal complex CC8, with the following predominant sequence types (STs)/clones: ST247-IA/Iberian, ST241-III/Finland-UK, and ST239-III/Brazilian. Most of the isolated strains harboured ermA and aacA-aphD genes, encoding additional resistance to macrolides, lincosamides, streptogramin B, and majority of aminoglycosides. They occurred also in Polish VRSA/TRSA population over the period, which was subjected for analysis: an increase in MIC values for glycopeptides, evolution in terms of the level and extent of resistance, and genetic re-assortment in epidemic clones. Conclusions: VRSA strains isolated from patients hospitalized at three Warsaw teaching hospitals in Poland, over a period of 17-years do not pose a threat as potential donors of van genes in horizontal-gene transfer processes, but are constantly evolving and represent international epidemic clones. [ABSTRACT FROM AUTHOR]