Results from the Survey of Antibiotic Resistance (SOAR) 2015-17 in Turkey: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

OBJECTIVES

To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2015-17 from Turkey.

METHODS

MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

RESULTS

A total of 179 S. pneumoniae and 239 H. influenzae isolates were collected. Few (27.9%) pneumococci were penicillin susceptible by CLSI oral or EUCAST low-dose breakpoints, but by EUCAST high-dose or CLSI IV breakpoints 84.4% were susceptible. The most active antibiotics (excluding penicillin IV) by CLSI breakpoints were fluoroquinolones (98.9% of isolates susceptible), ceftriaxone (83.2%), amoxicillin (78.8%) and amoxicillin/clavulanic acid (78.8%). Pneumococcal susceptibility to amoxicillin and amoxicillin/clavulanic acid was lower using EUCAST low-dose breakpoints (49.7%), although susceptibility increased when using EUCAST high-dose (57.0%-58.1%) and PK/PD (78.8%-87.7%) breakpoints. Twenty-three H. influenzae isolates were β-lactamase positive, with 11 characterized as β-lactamase negative and ampicillin resistant following EUCAST criteria and 5 by CLSI criteria. Generally antibiotic susceptibility was high using CLSI breakpoints: ≥92.9% for all antibiotics except ampicillin (87% by CLSI and EUCAST breakpoints) and trimethoprim/sulfamethoxazole (67.4% and 72% by CLSI and EUCAST breakpoints, respectively). Susceptibility using EUCAST breakpoints (where these are published) was similar, except for cefuroxime (oral) with 3.8% of isolates susceptible. PK/PD breakpoints indicated low susceptibility to macrolides (5.9%-10%) and cefaclor (13%). The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.

CONCLUSIONS

Antibiotic susceptibility of S. pneumoniae was generally low, which is in keeping with evidence of inappropriate and high antibiotic use in Turkey. H. influenzae susceptibility was high. These data are important for empirical therapy of CA-RTIs.

Results from the Survey of Antibiotic Resistance (SOAR) 2002-09 in Turkey

OBJECTIVES

To investigate changes in antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae from the Survey of Antibiotic Resistance (SOAR) in community-acquired respiratory tract infections (CA-RTIs) between 2002 and 2009 in Turkey.

METHODS

Previously published SOAR data were used for this analysis. MICs were determined using Etest(®) gradient strips or disc diffusion. Susceptibility against a range of antimicrobial agents was assessed using CLSI breakpoints.

RESULTS

A total of 900 S. pneumoniae isolates were analysed: 2002-03 (n = 75), 2004-05 (n = 301) and 2007-09 (n = 524). Four antibiotics were tested consistently throughout and three showed a statistically significant decrease in susceptibility (P < 0.0001): penicillin (74.7% susceptible in 2002-03; 67.8% in 2004-05; and 47.2% in 2007-09); cefaclor (85.3% in 2002-03; 78.7% in 2004-05; and 53.5% in 2007-09) and clarithromycin (85.3% in 2002-03; 82.7% in 2004-05; and 61.9% in 2007-09). Susceptibility to amoxicillin/clavulanic acid did not significantly change (100% in 2002-03; 98.7% in 2004-05; and 97.7% in 2007-09). A total of 930 H. influenzae isolates were analysed: 2002-03 (n = 133), 2004-05 (n = 379) and 2007-09 (n = 418). Four antibiotics were also consistently tested: ampicillin, amoxicillin/clavulanic acid, clarithromycin and cefaclor. All showed >90% susceptibility, but only cefaclor susceptibility significantly reduced (P < 0.0001) over time (99.2% in 2002-03; 96.3% in 2004-05; and 90.4% in 2007-09).

CONCLUSIONS

In S. pneumoniae from Turkey, there has been a clear statistically significant reduction in susceptibility to key antibiotics since 2002, but not to amoxicillin/clavulanic acid (or amoxicillin). However, susceptibility in H. influenzae remained stable. Continued surveillance is required to monitor future changes in antibiotic susceptibility for CA-RTI bacteria.

Results from the Survey of Antibiotic Resistance (SOAR) 2011-13 in Turkey

OBJECTIVES

Data are presented from the Survey of Antibiotic Resistance (SOAR) for respiratory tract infection pathogens collected in 2011-13 from Turkey.

METHODS

MICs were determined using Etest(®). Susceptibility was assessed using CLSI, EUCAST and pharmacokinetic/pharmacodynamic (PK/PD) interpretive criteria.

RESULTS

Rates of antibiotic susceptibility were very low among 333 isolates of Streptococcus pneumoniae tested: penicillin 38% using CLSI (oral) and EUCAST breakpoints; erythromycin 51% using CLSI and EUCAST criteria; and cefuroxime 64.6% using CLSI and PK/PD and 46.9% using EUCAST. Of the isolates, >90% were susceptible to amoxicillin/clavulanic acid, ceftriaxone (except using EUCAST criteria: 76%), levofloxacin and high-dose intravenous penicillin. Among 339 Haemophilus influenzae isolates, 6.8% were β-lactamase positive while 9.1% were β-lactamase negative but ampicillin resistant (BLNAR) by CLSI (14.7% by EUCAST) criteria. Amoxicillin/clavulanic acid susceptibility was ∼90% by CLSI (with or without BLNAR adjustment, EUCAST and high-dose PK/PD) but lower, at 82.9%, by EUCAST with BLNAR adjustment. Levofloxacin susceptibility was 96% using all three breakpoints. Dramatic differences in rates of susceptibility, depending on the breakpoints used, were seen for cefaclor [94% by CLSI (86.4% BLNAR adjusted), 23% by PK/PD] and cefuroxime [97% by CLSI (89.1% BLNAR adjusted), 85% by PK/PD, 15% by EUCAST (13.0% BLNAR adjusted)]. Streptococcus pyogenes (n = 222) and Moraxella catarrhalis (n = 40) isolates remained highly susceptible to amoxicillin/clavulanic acid, cephalosporins and levofloxacin, with only erythromycin susceptibility dropping below 95% for S. pyogenes.

CONCLUSIONS

Overall, amoxicillin/clavulanic acid and levofloxacin were the most active antibiotics based on all three breakpoints against these pathogens. Although susceptibility was not universally low in Turkey, high resistance rates were found in S. pneumoniae and, when using PK/PD and EUCAST breakpoints, in other respiratory pathogens.

In vitro activity of daptomycin alone and in combination with various antimicrobials against Gram-positive cocci

The increasing prevalence of resistant Gram-positive cocci requires the need to search for more effective agents and synergistic combinations. Forty-two vancomycin-resistant Enterococcus faecium (VREF), 30 methicillin-resistant Staphylococcus aureus (MRSA) and 36 Staphylococcus epidermidis (MRSE) strains were studied. Minimum inhibitory concentrations (MICs) were determined and synergy testing was performed by using E test for daptomycin, ampicillin-sulbactam, piperacillin-tazobactam and ticarcillin-clavulanate against staphylococci; for daptomycin, ampicillin, rifampin, and gentamicin against enterococci. Daptomycin in combination with ampicillin, rifampin, and gentamicin was tested against enterococci; daptomycin in combination with ampicillin-sulbactam, piperacillin-tazobactam, and ticarcillin-clavulanate was tested against staphylococci. Interaction categories were defined by the fractional inhibitory concentration (FIC) index. All strains of staphylococci and enterococci were susceptible to daptomycin. All three combinations showed synergy against more than 70% of the MRSA strains. Daptomycin in combination with ampicillin, rifampin, and gentamicin against enterococci showed synergies of 64.2%, 57.1% and 21.4%, respectively. This study indicates that daptomycin alone and combined with beta-lactams seems to be effective against MRSA, but further in vitro and in vivo studies on the subject are required before clinical use can be recommended.

Does Pharmaconutrition with L-Arginine and/or α-Tocopherol Improve the Gut Barrier in Bile Duct Ligated Rats?

BACKGROUND/AIM

Nitric oxide supplementation and antioxidant therapy modulate gut barrier function, but the relationships between enhanced nitric oxide production, antioxidant administration, and biliary obstruction remain unclear. We evaluated the role of nitric oxide and alpha-tocopherol supplementation in bile duct ligated rats.

METHODS

Fifty male Wistar albino rats underwent sham operation (group I; control animals) or bile duct ligation (groups II, III, IV, and V). The ligation groups received the following regimens: standard pellet diet (group II), pellet diet plus intramuscularly administered alpha-tocopherol (group III), and L-arginine-enriched pellet diet without (group IV) or with (group V) alpha-tocopherol. Nitric oxide, malondialdehyde, and alpha-tocopherol concentrations were assessed at the end of 3 weeks. Liver and intestinal samples were scored histologically. Mesenteric lymph node and liver cultures were assessed for bacterial translocation.

RESULTS

The liver malondialdehyde concentration was highest in group III. The nitric oxide content in the liver was higher in groups III and V, as were the blood alpha-tocopherol levels. Bacterial translocation was evident following bile duct ligation, but did not differ among the treatment groups. Intestinal histology revealed that group III had the lowest villus height, that group V had the least villus count, and that group II had the highest mucous cell count. The fibrosis scores were higher in groups IV and V.

CONCLUSIONS

An obvious effect of alpha-tocopherol (with or without L-arginine) on the gut barrier could not be demonstrated. Moreover, the L-arginine-enriched diet promoted fibrosis in the liver. Thus, while biliary duct obstruction triggers bacterial translocation, nitric oxide and/or alpha-tocopherol supplementation did not seem to improve the gut barrier in our model.

In vitro activity of fluoroquinolones against common respiratory pathogens

The treatment of respiratory infections is often empiric, necessitating the use of agents with a broad range of antimicrobial activity. The fluoroquinolones, having activity against common respiratory pathogens, fit this description. New fluoroquinolones have been developed in an attempt to improve the in vitro activity against a wide variety of respiratory tract pathogens. The objective of the study is to compare in vitro activity of newest fluoroquinolones, gatifloxacin and moxifloxacin, with levofloxacin and ciprofloxacin using three major respiratory pathogens, Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. Minimum inhibitory concentrations (MICs) of four fluoroquinolones were tested against 93 S pneumoniae, 62 H influenzae and 60 M catarrhalis, ie 215 isolates by the E-test method. National Committee for Clinical Laboratory Standards (NCCLS)-approved interpretive criteria were used throughout. All isolates were susceptible to the tested fluoro-quinolones. Ninety per cent of S pneumoniae strains were inhibited by ciprofloxacin at concentrations of 2 mg/L. The gatifloxacin and moxifloxacin MICs were lower than the ciprofloxacin and levofloxacin MICs against S pneumoniae. In contrast to S pneumoniae, in vitro activities of gatifloxacin and moxifloxacin offered no apparent advantages over ciprofloxacin and levofloxacin for H influenzae and M catarrhalis.

Experience with teicoplanin in the treatment of neonatal staphylococcal sepsis

We aimed to evaluate retrospectively the clinical and bacteriological efficacy and potential side-effects of teicoplanin treatment in neonates with proven staphylococcal infection. There were 37 episodes of staphylococcal septicaemia in neonates with a mean gestational age of 34.2 +/- 2.3 weeks; 26 were caused by coagulase-negative staphylococcal (CoNS) sepsis and 11 by Staphylococcus aureus sepsis. All episodes were treated with teicoplanin (intravenous loading dose 16 mg/kg followed by a maintenance dose of 8 mg/kg daily). The methicillin resistance and antibiotic susceptibilities of both micro-organisms were evaluated. Bacterial eradication was achieved in 89.1% of cases and mortality was 16.2%. The mean duration of treatment of the survivors was 11.6 +/- 2.3 days. There were no drug-related adverse events and the biochemical and haematological tests showed no clinically significant changes in relation to teicoplanin therapy. Our results suggest that teicoplanin is highly effective in neonatal staphylococcal sepsis.