Resistance Rates For Tetracycline Research Articles

Antimicrobial resistance, virulence factors and genetic lineages of hospital-onset methicillin-resistant Staphylococcus aureus isolates detected in a hospital in Zaragoza

IntroductionMRSA population dynamics is undergoing significant changes, and for this reason it is important to know which clones are circulating in our nosocomial environment. Materials and methodsA total of 118 MRSA isolates were collected from clinical samples from patients with previous hospital or healthcare contact (named as hospital-onset MRSA (HO-MRSA)) during a one year period. Susceptibility testing was performed by disk diffusion and microdilution. The presence of resistance genes and virulence factors were tested by PCR. All isolates were typed by SCCmec, spa and agr typing. PFGE and MLST were applied to a selection of them. ResultsEighty-three HO-MRSA isolates (70.3%) were resistant to any antibiotic included in the macrolide–lincosamide–streptogramin B group. Among these isolates, the M phenotype was the most frequent (73.5%). One hundred and seven of HO-MRSA isolates (90.7%) showed aminoglycoside resistance. The combination aac(6′)-Ie-aph(2″)-Ia+ant(4′)-Ia genes was the most frequent (22.4%). Tetracycline resistance rates in HO-MRSA isolates were low (3.4%), although a high level of mupirocin resistance was observed (25.4%). Most of the HO-MRSA isolates (approximately 90%) showed SCCmec type IVc and agr type II. Fifteen unrelated pulsotypes were identified. CC5 was the most prevalent (88.1%), followed by CC8 (5.9%), CC22 (2.5%), CC398 (2.5%) and CC1 (0.8%). ConclusionCC5/ST125/t067 lineage was the most frequent. This lineage was related to aminoglycoside resistance, and to a lesser extent, with macrolide resistance. The presence of international clones as EMRSA-15 (CC22/ST22), European clones as CC5/ST228, community clones related to CC1 or CC8 and livestock associated clones, as CC398, were observed in a low percentage.

Molecular epidemiology of Staphylococcus aureus in post-earthquake northern Haiti

Knowledge of nasal carriage is important in predicting staphylococcal infection, and no information exists regarding the endemicity of Staphylococcus aureus in Haiti. We performed a cross-sectional analysis of S. aureus nasal screening in an acute care, a subacute rehabilitation, and a community setting, with a brief medical and epidemiological history. PCR-positive S. aureus screening nasal cultures underwent molecular analysis for spa type, SCCmec type, and virulence genes (Panton-Valentine leukocidin (PVL), toxic shock syndrome toxin (TSST), and arginine catabolic mobile element (ACME)), and were evaluated for antibiotic susceptibility using commercial tests. Overall carriage rates of 8.4% methicillin-susceptible S. aureus (MSSA) and 2.8% methicillin-resistant S. aureus (MRSA) were identified, with a high rate of tetracycline resistance. TSST and PVL genes were identified in MSSA. MRSA isolates contained no virulence markers. Unique MSSA phenotypes (i.e., linezolid-resistant, vancomycin-sensitive/daptomycin non-susceptible) were identified, as were two PVL-positive ST152 MSSA colonization isolates, previously geographically limited to Africa. We found a low S. aureus carriage rate with complete vancomycin susceptibility and high tetracycline resistance, which has important public health implications with regard to treatment. Additionally, the finding of PVL-positive MSSA isolates, including the expansion of a previously described limited 'divergent' clone, ST152, warrants further evaluation.

Clone wars: Let's pick out the superbugs

Antibiotic Resistance Since the 1960s, group B streptococci (GBS) have lost genetic diversity, yet they cause more virulent neonatal infections and show high rates of tetracycline resistance. The puzzle is that tetracycline is not used to treat GBS. Nevertheless, since the 1950s, most GBS clones were wiped out by the collateral effects of the widespread use of tetracycline and other antibiotics, even though they were not the treatment target. Da Cunha et al. show that a few GBS clones survived by virtue of their persistence or virulence, and these clones also acquired mobile genetic elements carrying a mixture of antibiotic resistance genes, including those for tetracycline resistance. Nat. Comm. 10.1038/ncomms5544 (2014).

Estado actual de la resistencia de Helicobacter pylori a tetraciclina: revisión sistemática de la literatura

<strong>Objective</strong>. To determine the prevalence of Helicobacter pylori resistance to and the possible mutations that generate this worldwide resistance. <strong>Materials and methods</strong>. A systematic search for literature was performed in the databases Medline, Science Direct (Elsevier), Ovid, PubMed, Lilacs<br />and MedicLatina using relevant key words. Data extraction was independent and checklists were prepared to assess the methodological<br />quality of the studies. Analysis of information was done with RevMan 5®. <strong>Results</strong>. We found Helicobacter pylori resistance prevalence rates of 1% for North America, 8% for Central and South America, 5% for Asia, and 2% for Europe. The mutation associated to this resistance is in the 16S rDNA gene at nucleotide position 967TTC to AGA965 responsible of high resistance to tetracycline. <strong>Conclusions</strong>. Antibiotic resistance is one of the causes most associated to treatment failure in the eradication of Helicobacter pylori, as well as poor adherence to treatment and indiscriminate use of antibiotics. We also evidenced that the rate of tetracycline resistance is higher when<br />it is used in a second treatment scheme. The distribution of resistance is variable in different areas and it is important to know these resistances to avoid treatment failures.<br /><strong>Key words</strong>: Helicobacter pylori, tetracycline, resistance, mutation, treatment, epidemiology, 16S rRNA.

Molecular Mechanisms of Tetracycline and Macrolide Resistance andemmCharacterization ofStreptococcus pyogenesIsolates in Tunisia

Streptococcus pyogenes or group A Streptococcus, a major human pathogen, remains susceptible to beta-lactams, but resistance to other antibiotics is becoming more common. The purpose of this study was to characterize both phenotypic and genotypic epidemiological markers of group A Streptococcus and to identify the mechanisms of resistance to macrolides and tetracyclines. A total of 103 strains, isolated at Charles Nicolle University Hospital of Tunis, were investigated. The rate of resistance to erythromycin was low (5%), whereas a high rate of tetracycline resistance was found (70%). All the macrolide-resistant isolates expressed the constitutive macrolide, lincosamide, and streptograminB phenotype and harbored the erm(B) gene. Resistance to tetracycline was mainly due to the tet(M) gene, which is commonly associated with the conjugative transposon Tn916. No significant association was found between erm(B) and tet(M) genes. The tetracycline-resistant strains belonged to 28 distinct emm types. Among them, emm118 was the most prevalent type, followed by emm42, std432, emm76, and emm18. However, emm1, emm4, emm6, emm28, and emm3 were the most frequent types among tetracycline susceptible isolates. Only emm118 and emm42 types (p ≤ 0.05) were significantly associated with resistance to tetracycline.

English

Dental caries is the most common chronic disease. Tetracycline is commonly used in dental practice as a prophylactic agent and for treatment of oral infections. The wide use of tetracycline had resulted in a major increase in the rate of tetracycline resistance among bacteria. Substantial epidemiologic evidence links Streptococcus mutans to caries; the pathobiology of caries may involve more complex communities of bacterial species. Molecular methods for bacterial identification and enumeration now make it possible to more precisely study the micro biota associated with dental caries. The purpose of this study was to characterize the tetracycline resistant microorganism associated with the dental caries using cultural & molecular method. The first step involved 20 samples from patients with different level of dental caries. From which 33 different isolates were obtained, out of which 12 showed resistances to tetracycline and 5 were having maximum MIC indicating that they are highly resistant. These resistant microorganisms were identified to the species level by growing them on a suitable medium using the antibiotic tetracycline and were analyzed with the help of FAME analysis, which indicated that different strains of the Pseudomonas aeruginosa and Bacillus subtilis were present.The second step involved identifying the tet k gene in the cultures. Tet k was amplified under standard conditions by using specific primers results. Interestingly, the results showed that tet k gene was present in all the sample. Tet k gene is involved in imparting the resistant to the tetracycline by acting as a efflux pump. RFLP analyses were used in order to identify the polymorphic forms of the tet k. The HindIII digest suggest that high resistance to tetracycline was acquired due to some mutations in the genome.

Molecular characterization of invasive and non-invasive Streptococcus pyogenes isolates from Romania

In 2002, the Romanian National Reference Laboratory was invited to join the Strep-EURO project to study invasive Streptococcus pyogenes infections. During 2003 and 2004, a total of 33 isolates recovered from invasive disease were received from eight Romanian counties. For comparison, 102 isolates from non-invasive disease, as well as a collection of 12 old invasive strains (isolated between 1967 and 1980) were included. All isolates were characterized by several methods: T and emm typing, presence of the fibronectin-binding protein F1 gene (prtF1), serum opacity factor (sof), and superantigen (SAg) genes (speA, speB, speC, speF, speG, speH, ssa and smeZ). The recent invasive isolates exhibited 19 emm-types, of which emm1, emm81, emm76, emm49 and emm78 covered 57 % of the strains. Furthermore, multilocus sequence typing analysis revealed nine new sequence types, corresponding to emm types 1, 12, 49, 81, 92, 100, 106 and 119. The non-invasive isolates comprised 24 different emm types with a predominance of emm1 and 12; the old invasive strains were of eight emm types, of which four were unique for this group. All isolates harboured speB and speF; smeZ was detected in all invasive strains, except for the emm49 and emm81 isolates. The majority of isolates from carriers, and patients with pharyngitis were prtF1 positive, most of these (14 strains) being emm12. High tetracycline resistance rates were noted among both invasive and control isolates (54 % and 35 %, respectively), whereas macrolide resistance rates were low (3 % and 5 %, respectively). Active and continuing surveillance is required to provide an accurate assessment of the disease burden and to provide epidemiological data on the character of isolates in Romania.

Changes in antibiotic resistance rates of invasive Haemophilus influenzae isolates in England and Wales over the last 20 years

The aim of this study was to determine trends in antibiotic resistance profiles of invasive clinical Haemophilus influenzae isolates over the last 20 years. Microbiology laboratories throughout England and Wales regularly submit invasive H. influenzae isolates to the Health Protection Agency for serotyping and antimicrobial susceptibility testing. Antimicrobial resistance was defined using the British Society for Antimicrobial Chemotherapy criteria (http://bsac.org.uk). All H. influenzae isolates from blood and cerebrospinal fluid (CSF) cultures between January 1985 and December 2004 were included. Over the 20 year study period, 6805 H. influenzae isolates from blood (n = 4932, 72.5%) and CSF (n = 1873, 27.5%) were obtained. Over half the isolates (3736/6805, 54.9%) were identified as Hib, 38.9% (n = 2644) as non-capsulated and 6.2% (n = 425) as other capsulated serotypes. Resistance to ampicillin was highest at 16.2%, followed by trimethoprim (7.7%), tetracycline (1.8%) and chloramphenicol (1.2%). All isolates were susceptible to cefotaxime and only four (0.06%) were resistant to rifampicin. When analysing trends, chloramphenicol and tetracycline resistance rates have remained low since the late 1980s. Ampicillin resistance increased slowly until the mid-1990s and then gradually declined to its lowest rate of 11.6% in 2004. Resistance to trimethoprim initially fell from 10% in 1985 to 1.8% in 1989, but has continued to rise since then to 11.9% in 2004. In a logistic regression model, year of isolate (P < 0.001), non-capsulated H. influenzae (P < 0.001) and younger age (P = 0.004) remained independently associated with trimethoprim resistance. Rifampicin and cefotaxime remain highly effective against all invasive H. influenzae isolates. Resistance to ampicillin, chloramphenicol and tetracycline has declined over the past 10 years, but trimethoprim resistance continues to increase rapidly. This finding requires further study but may reflect increased use of trimethoprim in the childhood population.

Tigecycline (GAR-936) activity against Streptococcus gallolyticus (bovis) and viridans group streptococci

Viridans group streptococci including Streptococcus gallolyticus (formerly S. bovis) represent serious invasive pathogens often associated with endocarditis or sepsis among immunocompromised or cancer patients. Tigecycline (GAR-936), the first clinically studied glycylcycline, has a potent Gram-positive activity with a potential treatment option for these streptococcal infections. The studied collection (848 strains) included 100 isolates each of Streptococcus anginosus, Streptococcus constellatus, Streptococcus intermedius, Streptococcus mitis, Streptococcus oralis, Streptococcus salivarius, Streptococcus sanguis, and fewer strains of S. gallolyticus (98 strains) and Streptococcus mutans (50 strains). These strains were isolated from patients on 3 continents in the SENTRY Antimicrobial Surveillance Program and tested for susceptibility and interpreted by Clinical and Laboratory Standards Institute broth microdilution methods and criteria (≤0.25 μg/mL for tigecycline per US Food and Drug Administration). Penicillin susceptibility rates for the entire collection varied from 61% ( S. sanguis) to 98% ( S. constellatus), and macrolide susceptibility was also compromised (49–88%; average, 69%). Tigecycline was active against all isolates tested, in contrast to tetracycline resistance rates of 8–66%, and highest for S. gallolyticus. In conclusion tigecycline was quite active against bacteremic isolates of viridans group streptococci species and S. gallolyticus with an overall MIC 90 at ≤0.06 μg/mL; the highest MIC was only 0.25 μg/mL.

Methicillin-resistant Staphylococcus aureus prevalence: current susceptibility patterns in Trinidad.

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) has become one of the most widespread causes of nosocomial infections worldwide. Recently, reports have emerged that S. aureus strains recovered from community-acquired infections are also methicillin-resistant. This study was undertaken to analyze the prevalence of methicillin resistance among isolates at a regional hospital in Trinidad, and document the current resistance profile of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) to the commonly used anti-staphylococcal agents.MethodsOver a 6-year period we analyzed 2430 isolates of S. aureus strains recovered from various clinical sources, from hospital and community practices. Antimicrobial susceptibility testing was done according to guideline recommendations of the National Committee for Clinical Laboratory Standards.ResultsThe prevalence of MRSA from surgical/burn wounds, urine and pus/abscess were 60.1%, 15.5% and 6.6%, respectively. The major sources of MSSA were surgical/burn wounds, pus/abscess and upper respiratory tract specimens with rates of 32.9%, 17.1% and 14.3%, respectively. The greatest prevalence of resistance of MRSA was seen for erythromycin (86.7%), and clindamycin (75.3%). Resistance rates among MSSA were highest for ampicillin (70%). Resistance rates for tetracycline were similar among both MRSA (78.7%) and MSSA (73.5%). The MRSA recovery rates from nosocomial sources (20.8%) was significantly higher than that of previous years (12.5%) (p < 0.001), whereas rates among community isolates were relatively similar for the same period (4.1% versus 8.1%).ConclusionThe prevalence of MRSA in the hospital increased from 12.5% in 1999 to 20.8% in 2004. Most isolates were associated with infected surgical/burn wounds which may have become infected via the hands of HCPs during dressing exercises. Infection control measures aimed at the proper hand hygiene procedures may interrupt the spread of MRSA. HCPs may also be carriers of MRSA in their anterior nares. Surveillance cultures of both patients and HCPs may help to identify carriers who would be offered antibiotics to eradicate the organisms. Most MRSA are resistant to several non-β-lactam antibiotics. Frequent monitoring of susceptibility patterns of MRSA and the formulation of a definite antibiotic policy maybe helpful in decreasing the incidence of MRSA infection.

Investigation of erythromycin and tetracycline resistance genes in methicillin-resistant staphylococci

In this study, erythromycin [ erm(A) and erm(C)] and tetracycline [ tet(K) and tet(M)] resistance genes were investigated by multiplex polymerase chain reaction (PCR) in a total of 56 methicillin-resistant ( mecA+) staphylococcal hospital isolates, 28 of which were determined to be Staphylococcus aureus (MRSA) and the other 28 were coagulase-negative staphylococci (MRCNS). Internal control primers amplifying a specific fragment of 16S rDNA of staphylococci were included in the multiplex PCR protocol to ensure the efficacy of amplification and to determine any PCR inhibition. No resistance genes were detected in 5 of 56 (8.9%) isolates in the study. In the study, tet(K) genes were detected widely (42.9%) in MRCNS, whilst tet(M) genes were detected in MRSA (50.0%). Regarding the erythromycin resistance genes, whilst erm(A) genes were detected in most (71.4%) MRSA isolates, detection rates of erm(C) genes were the same (64.3%) both in MRCNS and MRSA. The resistance rates for tetracycline and erythromycin were 57.1% and 78.6%, respectively, in MRSA isolates. In conclusion, in this study, the multiplex PCR technique including an internal control is shown to be a fast, sensitive, reliable, practical, reproducible and economic technique for the detection of erythromycin and tetracycline resistance in staphylococcal isolates.

Antimicrobial susceptibility and serotype distribution of Streptococcus pneumoniae causing meningitis in Egypt, 1998–2003

To determine the antimicrobial susceptibility and serotype distribution of 205 isolates of Streptococcus pneumoniae, collected from the CSF of meningitis patients identified between 1998-2003, during sentinel meningitis surveillance in Egypt. Antimicrobial susceptibility was evaluated against six antibiotics using disc diffusion and Etest methods. Serotyping was performed by latex agglutination and the Quellung test. Forty-nine percent of all isolates were found to be non-susceptible to penicillin (46% intermediate, MIC range 0.12-1.0 mg/L; 3% resistant, MIC = 2.0 mg/L), and 6% of the isolates were non-susceptible to ceftriaxone (5% intermediate, MIC = 1.0 mg/L; 1.3% resistant, MIC >/= 2 mg/L). Resistance rates for tetracycline and trimethoprim/sulfamethoxazole were high (52 and 59.7%, respectively), but those for erythromycin and chloramphenicol were lower (11 and 9%, respectively). Five serotypes (6B, 1, 19A, 23F and 6A) accounted for 37% of the total isolates. Ten isolates (5%) were non-typeable. Overall, 29 and 42% of serotypes were represented in the 7- and 11-valent conjugate vaccines, respectively. However, vaccine coverage for children <2 years was 38 and 56% for the 7- and 11-valent, respectively. Resistance to penicillin may be increasing among S. pneumoniae strains causing meningitis in Egypt, and a moderate proportion of these strains are not covered by current pneumococcal conjugate vaccines. In addition to intensifying education efforts about judicious use of antibiotics, laboratory-based surveillance for other forms of invasive pneumococcal disease, especially pneumonia, is needed before decisions can be made regarding the most effective vaccines for control of this disease in Egypt.

Association of Ureaplasma urealyticum biovars with clinical outcome for neonates, obstetric patients, and gynecological patients with pelvic inflammatory disease.

In this prospective study, the prevalence of the two Ureaplasma urealyticum biovars, parvo and T960, was determined in pregnant women and in gynecological patients colonized by ureaplasmas. Furthermore, we investigated the association of these biovars with gynecological complications and adverse pregnancy outcome. Isolates of U. urealyticum from 254 women were biotyped by a PCR method recently developed. The parvo biovar was found in 81% (206 of 254) of the patients, and the T960 biovar was found in 30% (76 of 254) of the patients; 6% (14 of 254) of the women were coinfected. Identical biovars were detected in mothers and their infants. Serial isolations or cultures from different sampling sites of the same individual revealed the same biovar. T960 was dominant in patients with pelvic inflammatory disease (57%) and patients who had had a miscarriage (42%), showed a higher rate of tetracycline resistance than did parvo isolates (55 versus 18%), and seemed to have more adverse effects on pregnancy outcome with regard to birth weight (2,500 versus 1,720 g), gestational age (35 versus 30 weeks), and preterm delivery (35 versus 77%).

Occurrence of plasmids and tetracycline resistance among Campylobacter jejuni and Campylobacter coli isolated from whole market chickens and clinical samples

Twenty whole market chickens, purchased from 10 different stores in the Taipei Metropolitan area, were examined for the presence of Campylobacter jejuni and Campylobacter coli. The microorganisms were recovered from 95% of the chickens. A survey of different sites on — breast, thigh and tail — showed that contamination was equally common on all these sites. One hundred and sixty-seven chicken isolates and the 41 clinical isolates of Campylobacter jejuni were examine for the occurrence of plasmid DNA in association with tetracycline resistance. A high plasmid occurrence rate of 91% and 44% was observed for C. jejuni from chickens and clinical isolates, respectively. Plasmids ranged in size from 16 to 208 Kb. A 61 Kb plasmid and a 50 Kb plasmid were common to the chicken isolates and clinical isolates, respectively. All chicken isolates and 78% of clinical isolates were tetracycline-resistant. The high rate of tetracycline resistance in chicken isolates probably related to use of tetracycline as a growth promoter for poultry. A tetO DNA Probe, highly specific for the detection of tetracycline resistance in C. jejuni and C. coli, was used to find the location of tetracycline resistance. Of 157 chicken isolates, 98% of isolates were positive with the tetO probe, 87% ( 137 157 ) on plasmids and 11% ( 17 157 ) on the chromosome; only three isolates did not hybridize with the tetO probe. Of 32 clinical isolates, 88% isolates hybridized with the tetO probe, 47% ( 15 32 ) on plasmids and 41% ( 13 32 ) on the chromosome; four isolates did not hybridize with the tetO probe.