Antimicrobial resistance patterns of respiratory pathogens: a local report from Turkey

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.

Antibiotic Resistance in PathogenicStreptococcus pneumoniaeIsolates in Turkey

Streptococcus pneumoniae causes various human infections such as meningitis, septicemia, otitis media, sinusitis, and pneumonia. Antibiotic resistance has already been reported with increasing frequency worldwide and is spreading. The earliest studies on pneumococcal antibiotic resistance go back to the late 1980s in Turkey. The resistance patterns have elevated with stepwise increments since then. By the beginning of 2005, approximately 40% of pneumococci were resistant to penicillin and nearly one-fifth of resistant isolates present high-level penicillin resistance. This proves that penicillin is still a good alternative for nonmeningeal infections. In addition, no ceftriaxone resistance have been reported in local Turkish studies, but cefuroxime, a second-generation cephalosporin, was recorded to have (10.8-20%) resistance rates. The most frequently assessed antibiotics other than penicillin in Turkish studies include erythromycin (4-19.4%), chloramphenicol (2-10%), clindamycin (2.5-13%) and tetracycline (13-28.6%) and all have various resistance profiles. On the other hand, nearly all or almost all of the isolates evaluated in Turkish studies are susceptible to rifampicin, quinolones, linezolid, quinupristin-dalfopristin and telithromycin. All these non-beta-lactam antibiotics except the tetracyclines are within acceptable limits of empirical approaches. Tetracycline must be used cautiously. In addition, trimethoprim sulfamethoxazole cannot be prescribed in probable pneumococcal infections since more than half of the isolates are nonsusceptible.

A survey of antibiotic resistance in Streptococcus pneumoniae and Haemophilus influenzae in Turkey, 2004–2005

OBJECTIVES

To determine the prevalence of antimicrobial resistance among Streptococcus pneumoniae and Haemophilus influenzae isolated in Turkey as part of Survey Of Antibiotic Resistance, a surveillance programme in the Africa and Middle East region examining the antimicrobial susceptibility of key bacterial pathogens involved in community-acquired respiratory tract infections (CARTIs).

METHODS

Susceptibility was evaluated against a range of antimicrobial agents using disc diffusion and Etest methods.

RESULTS

Six centres in five cities collected 301 S. pneumoniae and 379 H. influenzae isolates between October 2004 and November 2005. Among S. pneumoniae, the prevalence of isolates with intermediate susceptibility (MICs 0.12-1 mg/L) and resistance to penicillin (MICs >or=2 mg/L) was 24.6% and 7.6%, respectively; there was a wide variation between cities (2.4% to 36.9% intermediate and 0% to 23.8% resistant phenotypes). Macrolide-azalide resistance rates exceeded those of penicillin resistance in all cities. Overall, 5.0% of isolates were co-resistant to penicillin and erythromycin and 10.0% were multidrug-resistant (joint resistance to erythromycin, co-trimoxazole and tetracycline). Agents tested to which over 90% of countrywide S. pneumoniae isolates remained susceptible were amoxicillin/clavulanate (98.7%), chloramphenicol (94.7%) and cefprozil (90.6%). Overall, the percentage of H. influenzae isolates producing beta-lactamase was 5.5%, differing widely across the country with the highest prevalence of beta-lactamase production detected in Trabzon (14.0%) and no beta-lactamase-positive isolates found in Izmir. H. influenzae had the highest per cent susceptibility to amoxicillin/clavulanate (99.5%) and ofloxacin (99.2%) while >20% were resistant to co-trimoxazole.

CONCLUSIONS

Prevalence of penicillin and macrolide-azalide resistance among S. pneumoniae appears to be on the increase in Turkey while overall beta-lactamase production in H. influenzae remains relatively low. To adequately monitor the spread of drug-resistant phenotypes among these two important CARTI pathogens, ongoing collection of resistance surveillance data is required-where possible locally as resistance patterns can vary substantially between cities and institutions.

Therapeutic options for pneumococcal pneumonia in Turkey

BACKGROUND

Community-acquired pneumonia (CAP) is a leading cause of morbidity and mortality worldwide. Streptococcus pneumoniae continues to be the most important causative agent in CAP.

OBJECTIVE

This article reviews options for the empiric treatment of pneumococcal pneumonia in Turkey based on local epidemiologic data.

METHODS

This was a retrospective review of studies evaluating antimicrobial susceptibility patterns among clinical isolates of S pneumoniae in Turkey from 2000 onward. Relevant studies were identified through literature searches of both Turkish (Ulakbim and Pleksus) and international (MEDLINE) databases using the search terms S pneumoniae and Turkey. Only antibiotics likely to be used in pneumococcal pneumonia were evaluated. The minimum concentration required to inhibit 90% of isolates (MIC(90)) for each antibiotic was obtained by averaging all reported values to arrive at a single value for the entire country.

RESULTS

The MIC(90) for penicillin was 1 g/mL; among all isolates of S pneumoniae, 6.4% were penicillin resistant and 30.9% showed intermediate susceptibility. The MIC(90)s and overall rates of resistance (combined intermediate susceptibility and resistance) for the other antibiotics studied were as follows: cefaclor, 4 microg/mL (26.3%); cefuroxime, 2 microg/mL (15.4%); ceftriaxone, 0.25 microg/mL (0.75%); imipenem, 0.06 microg/mL (0%); erythromycin, 2 microg/mL (13.9%); clarithromycin, 2 microg/mL (13.7%); azithromycin, 2 microg/mL (13.8%); telithromycin, 0.06 microg/mL (no published breakpoints); trimethoprim-sulfamethoxazole, 4 microg/mL (63.8%); tetracycline, 16 microg/mL (24.6%); ciprofloxacin, 2 microg/mL (no published breakpoints); ofloxacin, 2 microg/mL (4%); levofloxacin, 1 microg/mL (0%); gemifloxacin, 0.06 microg/mL (no published breakpoints); and moxifloxacin, 0.06 microg/mL (0%). Penicillin G, at standard parenteral doses, has been shown to achieve concentrations above the MIC for >40% to 100% of the dosing interval, depending on the MIC of the isolate. Based on pharmacodynamic studies, the MIC(90) for penicillin in Turkey should easily be exceeded with the use of penicillin G 3 mU QID. In vitro, susceptibility is generally greater to amoxicillin than to penicillin, with average amoxicillin MIC values approximately 1 dilution lower than those for penicillin. Amoxicillin's better pharmacodynamic/pharmacokinetic properties relative to penicillin make it a reasonable option for the treatment of CAP. In pharmacodynamic studies, amoxicillin 1 g TID achieved and maintained serum concentrations of 2 to 4 microg/mL for at least 40% of the dosing interval. A new formulation of amoxicillin/clavulanate given 2000/125 mg BID is expected to eradicate isolates of S pneumoniae at an amoxicillin MIC < or = 4 microg/mL.

CONCLUSIONS

Based on data from Turkish surveillance studies performed from 2000 onward, high-dose parenteral penicillin G and parenteral/oral amoxicillin may be initial choices for the empiric treatment of uncomplicated pneumococcal pneumonia in Turkey. If these agents cannot be used for any reason, other options include parenteral cefuroxime, ceftriaxone, cefotaxime, newer quinolones, macrolides, and telithromycin. Due to elevated rates of resistance in Turkey, trimethoprim-sulfamethoxazole and tetracyclines are not recommended for empiric use in these infections.