Enterobacteriaceae
The MIC90, susceptibility rate and resistance rate of levofloxacin and other antibiotics against Escherichia coli are shown in Table 1.
Table 1
Antimicrobial activity of antimicrobial agents against E.coli by year
Antibiotic | 2009–2010(n = 1156) | 2011–2012(n = 694) | 2013–2014(n = 806) | 2015–2016(n = 721) | 2017–2018(n = 738) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 32 | 31.3 | 66.4 | 32 | 32.0 | 67.3 | 32 | 32.3 | 64.0 | 32 | 37.3 | 59.8 | 32 | 34.6 | 59.5 |
ciprofloxacin | 128 | 27.3 | 69.0 | 128 | 30.1 | 68.0 | 128 | 31.1 | 66.4 | 128 | 34.1 | 61.9 | 128 | 33.5 | 61.9 |
P/T | 8 | 93.5 | 4.4 | 8 | 90.6 | 6.9 | 32 | 89.8 | 5.5 | 16 | 92.1 | 5.0 | 16 | 90.7 | 6.2 |
Cefazolin | > 256 | 21.3 | 75.3 | > 256 | 22.2 | 74.6 | > 256 | 16.0 | 76.7 | > 256 | 22.5 | 71.2 | > 256 | 27.0 | 65.7 |
Cefoxitin | NT | NT | NT | NT | NT | NT | 64 | 73.6 | 17.9 | 32 | 74.1 | 14.3 | 32 | 73.8 | 16.1 |
Cefotaxime | > 256 | 27.6 | 71.9 | 256 | 28.0 | 71.6 | > 256 | 29.4 | 70.2 | > 256 | 35.0 | 64.3 | > 256 | 40.0 | 59.5 |
Cefatriaxone | > 256 | 27.4 | 72.2 | 256 | 27.5 | 72.3 | > 256 | 29.7 | 70.1 | > 256 | 35.4 | 64.3 | > 256 | 40.1 | 59.6 |
Ceftazidime | 64 | 62.4 | 33.4 | 64 | 57.3 | 35.0 | 128 | 55.7 | 38.5 | 128 | 61.9 | 31.5 | 64 | 59.5 | 33.1 |
CSL | 64 | 68.4 | 13.5 | 32 | 80.4 | 9.1 | 64 | 71.2 | 11.4 | 64 | 73.5 | 11.0 | 64 | 79.0 | 10.3 |
Cefepime | 64 | 39.6 | 34.9 | 32 | 42.9 | 26.5 | 128 | 41.2 | 38.6 | 64 | 45.8 | 33.8 | 64 | 52.3 | 28.3 |
Imipenem | 0.12 | 99.6 | 0.3 | 0.12 | 99.3 | 0.4 | 0.25 | 98.6 | 1.2 | 0.25 | 97.5 | 2.4 | 0.12 | 98.1 | 1.8 |
Meropenem | 0.03 | 99.4 | 0.4 | 0.03 | 99.1 | 0.4 | 0.06 | 98.4 | 1.5 | 0.03 | 98.1 | 1.8 | 0.03 | 98.1 | 1.6 |
gentamicin | 128 | 40.7 | 58.5 | 128 | 40.8 | 57.6 | 128 | 48.8 | 50.7 | 128 | 53.1 | 46.6 | 256 | 53.1 | 46.3 |
Amikacin | 8 | 92.7 | 6.4 | 4 | 93.9 | 5.8 | 4 | 96.9 | 2.9 | 8 | 96.8 | 2.8 | 8 | 95.9 | 2.8 |
S, Susceptible rate (%); R, Resistant rate (%); P / T, piperacillin / tazobactam; CSL, Cefoperazone / sulbactam; Cefoperazone / sulbactam were determined according to the standard of cefoperazone (susceptibility: ≤ 16 mg / L; resistance ≥ 64 mg / L); NT, not detected. |
The MIC90 of levofloxacin to Escherichia coli was unchanged in the past decade, and the resistance rate appeared stable with slightly decrease, ranged from 67.3–59.5%. The resistance rate, trend of levofloxacin and the cumulative inhibitory percentage of MIC were similar to those of the third generation cephalosporins such as cefotaxime and ceftriaxone (Table 1) (Fig. 1). To investigate the effect of ESBLs on the resistance of E.coli, we compared the resistance rate of levofloxacin of ESBLs producing and no-producing strains. The ESBL-positive strains showed resistance rates to levofloxacin over 70%, about 30 percentage points higher than that of ESBL-negative strains, while the resistance rate of strains isolated from ICU to levofloxacin is not significantly higher than that of non-ICU strains(by 13 percentage points in 2017–2018 than that of last period). The results of strains isolated from the different sources show that the drug resistance rate of strains from urine source is slightly higher than that of strains from blood and sputum source. The high resistance rate of strains from sputum source in 2017–2018 may be related to the small number of strains (19 strains). Comparison of different age group shows no difference in the levofloxacin resistance rates by age group (18–64, 65–74, ≥ 75 year old age groups) (Fig. 2).
In recent ten years, there was an increase in the MIC90 for levofloxacin against Klebsiella pneumoniae. Resistance rate of levofloxacin against Klebsiella pneumoniae has increased from 24.9% in 2009–2010 to 36.5% in 2017–2018 and the resistance rate of ciprofloxacin increased from 29.3% in 2009–2010 to 45.0% in 2017–2018, with the most significant increase in 2017–2018 both, which are about 8% higher than the previous period. The piperacillin / tazobactam resistance rate increased from 10.7% in 2009–2010 to 25.6% in 2017–2018 whereas aminoglycosides resistance rate was stable; the resistance rate of carbapenems increased significantly from about 1.0% in 2009–2010 to about 19.0% in 2017–2018, and different from fluoroquinolones, it increased at a constant rate (Table 2). Figure 3 shows that the bacteriostasis cumulative percentage curve of levofloxacin in 2017–2018 slightly deviates to the right which means high MIC. From 2009 to 2016, the resistance rate of ESBL-producing Klebsiella pneumoniae to levofloxacin increased, while that of non-ESBL-producing Klebsiella pneumoniae was significantly lower, stable at 15.7% − 17.9%; the resistance rate of ESBL-producing Klebsiella pneumoniae to levofloxacin in 2017–2018 fell to the level of 2013–2014, while the resistance rate of non-ESBL-producing Klebsiella pneumoniae increased to 30.9%; the resistance rate of carbapenems also showed the same trend (the results were not shown). Compared with non-ICU, the resistance rate of strains isolated from ICU was higher and increased faster. There was no significant difference in levofloxacin resistance between the strains isolated from blood and sputum. The resistance rate to levofloxacin increased with the increase of age in 2009–2012, but no difference in the levofloxacin resistance rates between close age groups was observed (Table 4).
Table 2
Antimicrobial activity of antimicrobial agents against Klebsiella pneumoniae by year
Antibiotic | 2009–2010(n = 845) | 2011–2012(n = 510) | 2013–2014(n = 584) | 2015–2016(n = 563) | 2017–2018(n = 602) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 16 | 68.6 | 24.9 | 32 | 64.1 | 29.2 | 16 | 61.3 | 29.8 | 32 | 63.4 | 29.0 | 64 | 52.7 | 36.5 |
ciprofloxacin | 32 | 59.2 | 29.3 | 64 | 55.5 | 34.1 | 64 | 51.4 | 38.7 | 64 | 56.1 | 36.6 | 128 | 47.8 | 45.0 |
P/T | 128 | 86.0 | 10.7 | 128 | 86.5 | 11.2 | > 256 | 83.9 | 13.5 | > 256 | 76.2 | 21.0 | > 256 | 71.9 | 25.6 |
Cefazolin | > 256 | 41.4 | 57.0 | > 256 | 42.5 | 55.7 | > 256 | 40.4 | 53.1 | > 256 | 45.8 | 47.4 | > 256 | 40.2 | 53.0 |
Cefoxitin | NT | NT | NT | NT | NT | NT | 256 | 74.3 | 22.3 | 256 | 73.4 | 22.4 | > 256 | 66.8 | 29.4 |
Cefotaxime | 256 | 47.1 | 51.5 | 256 | 47.8 | 50.4 | > 256 | 50.5 | 49.0 | > 256 | 56.3 | 43.2 | > 256 | 51.5 | 48.2 |
Cefatriaxone | 256 | 47.5 | 51.5 | 256 | 48.2 | 50.8 | > 256 | 50.7 | 48.6 | > 256 | 56.5 | 43.0 | > 256 | 52.0 | 48.0 |
Ceftazidime | 128 | 67.6 | 26.6 | 128 | 65.5 | 28.8 | 256 | 64.7 | 32.2 | > 256 | 66.1 | 29.8 | > 256 | 61.8 | 34.7 |
CSL | 64 | 75.3 | 13.1 | 64 | 74.3 | 12.5 | 128 | 69.3 | 20.2 | > 256 | 70.5 | 22.6 | > 256 | 65.0 | 28.7 |
Cefepime | 32 | 64.4 | 22.2 | 32 | 62.4 | 23.5 | 128 | 59.6 | 30.5 | 128 | 63.1 | 27.0 | 256 | 57.1 | 35.0 |
Imipenem | 0.12 | 98.7 | 1.2 | 0.25 | 96.1 | 3.5 | 2 | 89.6 | 9.1 | 32 | 84.9 | 14.6 | 64 | 80.1 | 19.1 |
Meropenem | 0.03 | 98.6 | 0.8 | 0.06 | 95.7 | 4.1 | 4 | 89.4 | 10.1 | 16 | 84.9 | 14.4 | 128 | 79.9 | 19.6 |
gentamicin | > 256 | 60.9 | 38.1 | 256 | 62.7 | 36.3 | 128 | 68.2 | 31.2 | 256 | 68.9 | 30.2 | > 256 | 69.8 | 29.4 |
Amikacin | > 256 | 88.3 | 11.2 | 8 | 90.4 | 9.4 | 8 | 91.8 | 8.2 | > 256 | 87.2 | 11.7 | > 256 | 86.7 | 13.1 |
S, Susceptible rate (%); R, Resistant rate (%); P / T, piperacillin / tazobactam; CSL, Cefoperazone / sulbactam; Cefoperazone / sulbactam were determined according to the standard of cefoperazone (susceptibility: ≤ 16 mg / L; resistance ≥ 64 mg / L); NT, not detected. |
Table 4
Antimicrobial activity of antimicrobial agents against Acinetobacter baumannii by year
Antibiotic | 2009–2010(n = 794) | 2011–2012(n = 600) | 2013–2014(n = 647) | 2015–2016(n = 626) | 2017–2018(n = 671) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 16 | 34.3 | 40.9 | 16 | 25.8 | 54.3 | 16 | 25.8 | 63.5 | 32 | 25.1 | 62.9 | 32 | 29.1 | 65.1 |
ciprofloxacin | 128 | 28.1 | 71.2 | 128 | 23.8 | 76.0 | 128 | 24.7 | 75.3 | 128 | 24.6 | 75.1 | 256 | 28.8 | 71.2 |
P/T | > 256 | 27.3 | 63.0 | > 256 | 24.2 | 71.5 | > 256 | 24.3 | 74.7 | > 256 | 12.8 | 76.0 | > 256 | 26.1 | 72.6 |
Cefotaxime | > 256 | 21.2 | 71.5 | > 256 | 12.8 | 74.5 | > 256 | 12.7 | 75.0 | > 256 | 10.1 | 74.8 | > 256 | 13.9 | 71.4 |
Cefatriaxone | > 256 | 14.6 | 71.9 | > 256 | 9.7 | 74.8 | > 256 | 4.9 | 74.3 | > 256 | 6.2 | 75.4 | > 256 | 8.5 | 71.5 |
Ceftazidime | > 256 | 28.6 | 70.8 | > 256 | 25.7 | 73.7 | > 256 | 25.5 | 73.9 | > 256 | 25.6 | 73.2 | > 256 | 26.7 | 71.5 |
CSL | 64 | — | — | 128 | — | — | 128 | — | — | 256 | — | — | 128 | — | — |
Cefepime | 128 | 28.2 | 56.2 | 256 | 26.0 | 62.3 | 256 | 24.0 | 72.5 | 256 | 24.1 | 71.9 | 256 | 26.8 | 70.6 |
Imipenem | 64 | 42.2 | 55.8 | 64 | 33.2 | 65.3 | 64 | 28.6 | 70.5 | 64 | 29.1 | 69.8 | 64 | 27.9 | 71.4 |
Meropenem | 64 | 40.8 | 57.1 | 128 | 31.5 | 67.3 | 128 | 28.3 | 70.6 | 64 | 27.3 | 71.4 | 64 | 27.7 | 71.7 |
gentamicin | > 256 | 25.3 | 73.7 | > 256 | 24.7 | 75.0 | > 256 | 26.7 | 72.6 | > 256 | 26.4 | 72.0 | > 256 | 30.3 | 65.4 |
Amikacin | > 256 | 32.0 | 67.1 | > 256 | 33.2 | 66.2 | > 256 | 33.7 | 66.0 | > 256 | 34.0 | 65.5 | > 256 | 40.5 | 58.9 |
S, Susceptible rate (%); R, Resistant rate (%); P / T, piperacillin / tazobactam; CSL, Cefoperazone / sulbactam; —, no criteria. |
The resistance rate of Enterobacter cloacae to levofloxacin has declined over the past decade, from 2009–2010(29.5%) to 2017–2018(18.3%). In addition to carbapenem resistance rate increased, other test drug resistance rate also showed a downward trend (Table 3).
Table 3
Antimicrobial activity of antimicrobial agents against Enterobacter cloacae by year
Antibiotic | 2009–2010(n = 241) | 2011–2012(n = 183) | 2013–2014(n = 207) | 2015–2016(n = 202) | 2017–2018(n = 186) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 16 | 67.2 | 29.5 | 16 | 66.1 | 24.6 | 16 | 70.5 | 21.7 | 32 | 71.3 | 20.3 | 8 | 72.0 | 18.3 |
ciprofloxacin | 32 | 63.1 | 33.2 | 16 | 62.8 | 31.1 | 32 | 65.7 | 25.6 | 32 | 69.3 | 22.3 | 16 | 69.4 | 21.5 |
P/T | > 256 | 72.6 | 19.9 | 128 | 77.0 | 14.2 | 128 | 78.7 | 13.0 | > 256 | 69.3 | 22.8 | 128 | 78.0 | 14.0 |
Cefotaxime | > 256 | 44.0 | 53.9 | > 256 | 43.7 | 55.7 | > 256 | 54.6 | 42.5 | > 256 | 50.5 | 46.5 | 256 | 52.7 | 44.6 |
Cefatriaxone | > 256 | 44.0 | 54.4 | 256 | 43.2 | 55.7 | > 256 | 54.1 | 43.5 | > 256 | 51.5 | 45.0 | > 256 | 54.8 | 43.0 |
Ceftazidime | 256 | 53.9 | 43.6 | 256 | 49.2 | 44.8 | 128 | 61.8 | 34.3 | 256 | 58.9 | 40.1 | 256 | 63.4 | 33.3 |
CSL | 128 | 58.5 | 37.3 | 64 | 53.0 | 37.7 | 128 | 61.8 | 31.9 | 128 | 59.9 | 37.1 | 64 | 78.5 | 13.4 |
Cefepime | 64 | 67.2 | 20.7 | 64 | 66.7 | 19.1 | 32 | 78.3 | 16.4 | 32 | 71.3 | 16.3 | 32 | 77.4 | 14.5 |
Imipenem | 0.25 | 98.3 | 0.8 | 0.25 | 95.6 | 3.3 | 1 | 92.8 | 4.8 | 4 | 88.6 | 10.4 | 1 | 90.9 | 7.5 |
Meropenem | 0.12 | 97.9 | 1.2 | 0.12 | 95.6 | 3.3 | 0.12 | 94.2 | 3.9 | 1 | 90.6 | 9.4 | 2 | 89.8 | 8.1 |
gentamicin | 256 | 60.6 | 36.9 | 128 | 71.0 | 28.4 | 128 | 78.3 | 18.4 | 128 | 81.7 | 15.8 | 128 | 87.1 | 12.4 |
Amikacin | 16 | 90.9 | 9.1 | 16 | 90.2 | 9.8 | 8 | 96.6 | 2.9 | > 256 | 8.0 | 91.0 | 8 | 96.2 | 3.2 |
S, Susceptible rate (%); R, Resistant rate (%); P / T, piperacillin / tazobactam; CSL, Cefoperazone / sulbactam; Cefoperazone / sulbactam were determined according to the standard of cefoperazone (susceptibility: ≤ 16 mg / L; resistance ≥ 64 mg / L). |
Other Gram‑negative Organisms
From 2009 to 2014, the resistance rate of Acinetobacter baumannii to levofloxacin increased from 40.9–63.5%, and then remained stable at about 65%. The same trend was observed in other test drugs, carbapenems increased from about 55% to about 70% (Table 4), and Fig. 5 also showed the bacteriostasis cumulative percentage curve shift to the right. The levofloxacin resistance rate of imipenem sensitive strains is less than 20%, significantly lower than that of imipenem insensitive strains. The resistance rate of strains isolated from ICU is consistently about 20 percentage points higher than that of non-ICU strains. There was no significant difference in resistance rate between the strains from blood and sputum and among age groups (Fig. 6).
In recent ten years, there is almost no change in the MIC90 value and resistance rate of Pseudomonas aeruginosa against levofloxacin, and the resistance rate remained stable at about 30% (Table 5). Figure 7 shows that the proportion of strains with MIC value lower than 0.25 mg/l of levofloxacin decreased. The levofloxacin resistance rate of imipenem sensitive strains was significantly lower than that of non-sensitive strains. The resistance rate of strains isolated from ICU was most > 10 percentage points higher than that of non-ICU strains. The resistance rate of strains isolated from sputum was higher than that of strains isolated from blood, but the difference changes with the year, and there was no significant difference in resistance rate among age groups (Fig. 8).
Table 5
Antimicrobial activity of antimicrobial agents against Pseudomonas aeruginosa by year
Antibiotic | 2009–2010(n = 665) | 2011–2012(n = 620) | 2013–2014(n = 644) | 2015–2016(n = 658) | 2017–2018(n = 680) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 32 | 59.8 | 30.7 | 16 | 57.6 | 34.6 | 16 | 61.5 | 28.3 | 16 | 59.0 | 30.2 | 16 | 62.8 | 29.0 |
ciprofloxacin | 16 | 64.5 | 28.1 | 16 | 66.5 | 28.4 | 8 | 71.4 | 21.7 | 4 | 69.1 | 23.1 | 8 | 71.0 | 21.6 |
P/T | 128 | 71.1 | 17.3 | 128 | 69.0 | 15.0 | 256 | 69.1 | 19.6 | 256 | 70.1 | 18.5 | 256 | 76.6 | 15.9 |
Ceftazidime | 128 | 75.5 | 19.8 | 64 | 75.8 | 18.7 | 64 | 77.0 | 17.1 | 64 | 76.7 | 18.5 | 64 | 80.9 | 15.0 |
CSL | 128 | — | — | 128 | — | — | 128 | — | — | 128 | — | — | 128 | — | — |
Cefepime | 64 | 74.1 | 14.7 | 32 | 76.5 | 12.1 | 32 | 76.6 | 13.2 | 32 | 77.2 | 12.8 | 32 | 81.3 | 10.9 |
Imipenem | 16 | 63.2 | 33.7 | 16 | 65.2 | 29.0 | 32 | 67.1 | 28.0 | 32 | 64.6 | 29.5 | 32 | 67.5 | 29.7 |
Meropenem | 16 | 64.8 | 28.0 | 16 | 66.1 | 24.8 | 16 | 67.7 | 24.1 | 16 | 67.6 | 26.6 | 16 | 68.5 | 23.2 |
Gentamicin | > 256 | 65.3 | 33.1 | > 256 | 71.8 | 25.3 | > 256 | 78.9 | 18.3 | 256 | 83.0 | 13.5 | 16 | 85.7 | 10.6 |
Amikacin | > 256 | 78.9 | 20.0 | > 256 | 84.4 | 14.5 | 32 | 89.4 | 9.3 | 16 | 92.6 | 6.8 | 8 | 94.7 | 4.3 |
S, Susceptible rate (%); R, Resistant rate (%); P / T, piperacillin / tazobactam; CSL, Cefoperazone / sulbactam; —, no criteria. |
The levofloxacin resistance rate of Stenotrophomonas maltophilia was below 10% from 2009 to 2016, and increased slightly from 2017 to 2018. The resistance rates of levofloxacin, ticarcillin / clavulanate and minocycline were lower than 20%, while the intermediate rate of ticarcillin / clavulanate was nearly 50% (Table 6). Levofloxacin has a good antibacterial effect on Haemophilus influenzae, and the insensitivity rate is basically below 1% (Table 7).
Table 6
Antimicrobial activity of antimicrobial agents against Stenotrophomonas maltophilia by year
Antibiotic | 2009–2010(n = 245) | 2011–2012(n = 148) | 2013–2014(n = 176) | 2015–2016(n = 166) | 2017–2018(n = 167) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 4 | 89.8 | 9.4 | 4 | 85.1 | 8.8 | 4 | 86.9 | 9.7 | 8 | 86.7 | 10.2 | 8 | 82.6 | 15.0 |
Ticarcillin / clavulanic acid | 64 | 69.4 | 9.4 | 64 | 50.7 | 9.5 | 128 | 47.2 | 17.6 | 128 | 48.8 | 14.5 | 128 | 38.9 | 14.4 |
Ceftazidime | 128 | 47.7 | 44.5 | 256 | 30.4 | 62.2 | 256 | 40.9 | 51.1 | 256 | 34.3 | 54.2 | 256 | 33.5 | 58.1 |
minocycline | 1 | 98.4 | 0.0 | 4 | 95.3 | 2.7 | 2 | 94.9 | 2.8 | 2 | 98.8 | 1.2 | 4 | 95.2 | 3.0 |
SMZ-TMP | 0.5 | 91.4 | 8.6 | 64 | 83.1 | 16.9 | 1 | 93.8 | 6.2 | 4 | 88.0 | 12.0 | 8 | 59.9 | 40.1 |
chloramphenicol | 32 | 75.6 | 12.2 | 64 | 43.2 | 31.8 | 32 | 48.3 | 23.3 | 32 | 61.4 | 15.7 | 64 | 36.5 | 28.1 |
S, Susceptible rate (%); R, Resistant rate (%); SMZ-TMP: compound sulfamethoxazole |
Table 7
Antimicrobial activity of antimicrobial agents against Haemophilus influenzae by year
Antibiotic | 2009–2010(n = 88) | 2011–2012(n = 184) | 2013–2014(n = 142) | 2015–2016(n = 210) | 2017–2018(n = 252) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 0.5 | 100.0 | — | 0.25 | 98.9 | 1.1* | 0.12 | 100.0 | — | 0.5 | 99.5 | 0.5* | 0.5 | 99.6 | 0.4* |
ciprofloxacin | 0.5 | 97.7 | 2.3* | 0.25 | 98.4 | 1.6* | 0.25 | 98.6 | 1.4* | 0.5 | 98.1 | 1.9* | 1 | 96.8 | 3.2* |
Moxifloxacin | 0.5 | 96.6 | 3.4* | 0.25 | 97.8 | 2.1* | 0.5 | 96.5 | 3.5* | 0.5 | 96.2 | 3.8* | 1 | 94.8 | 5.2* |
ampicillin | 64 | 65.9 | 21.6 | 256 | 48.9 | 33.7 | 32 | 59.2 | 28.9 | 256 | 40.5 | 43.3 | > 256 | 27.4 | 63.1 |
P/T | 0.12 | 100.0 | 0.0 | 0.25 | 99.5 | 0.5 | 0.12 | 100.0 | 0.0 | 0.12 | 100.0 | 0.0 | 0.25 | 100.0 | 0.0 |
Cefotaxime | 0.06 | 100.0 | — | 0.06 | 98.4 | 1.6* | 0.12 | 100.0 | — | 1 | 97.6 | 2.4* | 1 | 96.4 | 3.6* |
Cefatriaxone | 0.016 | 100.0 | — | 0.016 | 100.0 | — | 0.03 | 100.0 | — | 0.25 | 100.0 | — | 0.25 | 100.0 | — |
Ceftazidime | 0.25 | 100.0 | — | 0.25 | 100.0 | — | 0.25 | 100.0 | — | 0.5 | 98.6 | 1.4* | 1 | 98.8 | 1.2* |
Cefepime | 0.25 | 98.9 | 1.1* | 0.5 | 98.4 | 1.6* | 1 | 97.9 | 2.1* | 2 | 94.8 | 5.2* | 2 | 90.9 | 9.1* |
Imipenem | 8 | 80.7 | 19.3* | 16 | 60.9 | 39.1* | 16 | 76.8 | 23.2* | 32 | 50.0 | 50.0* | 16 | 61.9 | 38.1* |
Meropenem | 0.5 | 100.0 | — | 0.5 | 96.7 | 3.3* | 0.5 | 90.8 | 9.2* | 0.5 | 92.9 | 7.1* | 0.5 | 94.8 | 5.2* |
Azithromycin | 2 | 93.2 | 6.8* | 4 | 92.9 | 7.1* | 4 | 90.8 | 9.2* | 128 | 76.7 | 23.3* | 64 | 74.2 | 25.8* |
S, Susceptible rate (%); R, Resistant rate (%); *insensitivity rate; —, no criteria. |
Gram‑positive Organisms
In the past ten years, the resistance rate of Staphylococcus aureus to levofloxacin and other fluoroquinolones has decreased continually (Table 8, Fig. 9). This trend also existed in β - lactams and aminoglycosides, while the resistance rate of macrolides changed little. The resistance rate of MRSA was significantly higher than that of MSSA, and the resistance rate of strains isolated from ICU was 10–20 percentage points higher than that of non-ICU strains. The resistance rate of strains from sputum was higher than that of strains from blood from 2009 to 2016, but that of strains from blood was slightly higher in 2017–2018. The resistance rate of strains isolated from the elderly aged 75 and over have the highest resistance rate to levofloxacin, and there is no significant difference between adults and young elderly group (Fig. 10).
Table 8
Antimicrobial activity of antimicrobial agents against Staphylococcus aureus by year
Antibiotic | 2009–2010(n = 630) | 2011–2012(n = 687) | 2013–2014(n = 751) | 2015–2016(n = 717) | 2017–2018(n = 756) |
MIC90 | S | I | R | MIC90 | S | I | R | MIC90 | S | I | R | MIC90 | S | I | R | MIC90 | S | I | R |
Levofloxacin | 32 | 50.8 | 0.8 | 48.4 | 32 | 56.9 | 0.6 | 42.5 | 64 | 70.0 | 0.7 | 29.3 | 32 | 73.2 | 0.3 | 26.5 | 32 | 76.1 | 1.2 | 22.8 |
ciprofloxacin | 64 | 45.9 | 4.4 | 49.7 | 128 | 52.1 | 4.8 | 43.1 | 128 | 62.3 | 5.3 | 32.4 | 64 | 64.4 | 7.8 | 27.8 | 64 | 66.4 | 8.7 | 24.9 |
Moxifloxacin | 8 | 51.1 | 2.5 | 46.3 | 8 | 57.8 | 3.6 | 38.6 | 8 | 70.3 | 0.5 | 29.3 | 8 | 73.5 | 0.3 | 26.2 | 8 | 77.1 | 1.7 | 21.2 |
Cefoxitin | 256 | 48.4 | — | 51.6 | 256 | 55.5 | — | 44.5 | > 256 | 56.5 | — | 43.5 | 256 | 60.7 | — | 39.3 | 256 | 67.6 | — | 32.4 |
Gentamicin | 128 | 47.9 | 1.9 | 50.2 | 64 | 56.5 | 4.4 | 39.2 | 128 | 63.8 | 2.3 | 34.0 | 64 | 69.9 | 2.5 | 27.6 | 64 | 75.4 | 0.9 | 23.8 |
Azithromycin | > 256 | 31.1 | 1.9 | 67.0 | > 256 | 23.6 | 1.7 | 74.7 | > 256 | 29.2 | 0.8 | 70.0 | > 256 | 34.3 | 0.4 | 65.3 | > 256 | 33.5 | 0.5 | 66.0 |
S, Susceptible rate (%); R, Resistant rate (%); I, intermediation rate (%); —, no criteria. |
Levofloxacin had some antibacterial action to Enterococcus faecalis, and the resistance rate had declined slightly in the past decade (Table 9). The resistance rate of Enterococcus faecium kept in about 85%, and that of other fluoroquinolones, ampicillin and erythromycin were also above 85% (Table 10).
Table 9
Antimicrobial activity of antimicrobial agents against Enterococcus faecalis by year
Antibiotic | 2009–2010(n = 111) | 2011–2012(n = 276) | 2013–2014(n = 311) | 2015–2016(n = 332) | 2017–2018(n = 342) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 128 | 62.2 | 36.9 | 64 | 69.2 | 29.0 | 64 | 65.3 | 31.2 | 64 | 66.6 | 31.6 | 64 | 73.1 | 25.7 |
Ciprofloxacin | NT | NT | NT | 64 | 63.8 | 29.7 | 64 | 60.1 | 31.5 | 64 | 58.4 | 32.2 | 64 | 57.9 | 26.0 |
Moxifloxacin | 32 | 63.1 | 32.4 | 16 | 72.5 | 26.1 | 16 | 70.1 | 28.9 | 16 | 69.0 | 29.5 | 16 | 74.9 | 24.0 |
Ampicillin | 128 | 82.9 | 17.1 | 4 | 92.8 | 7.2 | 4 | 94.2 | 5.8 | 2 | 95.5 | 4.5 | 2 | 96.8 | 3.2 |
Erythromycin | > 256 | 4.5 | 77.5 | > 256 | 2.5 | 76.4 | > 256 | 10.3 | 72.0 | > 256 | 7.2 | 67.5 | > 256 | 5.6 | 67.3 |
HLGM | — | 76.6 | 23.4 | — | 75.0 | 25.0 | — | 74.9 | 25.1 | — | 80.4 | 19.6 | — | 72.5 | 27.5 |
S, Susceptible rate (%); R, Resistant rate (%); HLGM, high concentration gentamicin; NT, not detected. |
Table 10
Antimicrobial activity of antimicrobial agents against Enterococcus faecium by year
Antibiotic | 2009–2010(n = 193) | 2011–2012(n = 299) | 2013–2014(n = 343) | 2015–2016(n = 348) | 2017–2018(n = 357) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 128 | 14.5 | 84.5 | 128 | 11.0 | 86.0 | 128 | 9.9 | 86.6 | 128 | 10.6 | 85.1 | 128 | 10.6 | 84.3 |
Ciprofloxacin | NT | NT | NT | 256 | 7.7 | 91.3 | > 256 | 6.7 | 90.7 | > 256 | 8.6 | 88.2 | > 256 | 8.1 | 90.8 |
Moxifloxacin | 32 | 14.0 | 83.4 | 32 | 8.4 | 87.0 | 32 | 7.9 | 88.9 | 64 | 10.6 | 86.2 | 64 | 9.2 | 88.2 |
Ampicillin | 128 | 15.0 | 85.0 | > 256 | 12.4 | 87.6 | 256 | 9.9 | 90.1 | > 256 | 14.9 | 85.1 | > 256 | 11.8 | 88.2 |
Erythromycin | > 256 | 3.6 | 88.6 | > 256 | 1.7 | 91.3 | > 256 | 3.8 | 87.8 | > 256 | 3.4 | 83.9 | > 256 | 4.8 | 84.3 |
HLGM | — | 30.9 | 69.1 | — | 42.8 | 57.2 | — | 44.0 | 56.0 | — | 51.1 | 48.9 | — | 58.8 | 41.2 |
S, Susceptible rate (%); R, Resistant rate (%); HLGM, high concentration gentamicin; NT, not detected. |
Levofloxacin had a good antibacterial effect on Streptococcus pneumoniae, and the resistance rate was always lower than 3% (Table 11).
Table 11
Antimicrobial activity of antimicrobial agents against Streptococcus pneumoniae by year
Antibiotic | 2009–2010(n = 352) | 2011–2012(n = 369) | 2013–2014(n = 340) | 2015–2016(n = 290) | 2017–2018(n = 300) |
MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R | MIC90 | S | R |
Levofloxacin | 1 | 98.6 | 0.9 | 2 | 97.6 | 1.1 | 2 | 91.8 | 2.4 | 1 | 97.9 | 2.1 | 2 | 97.7 | 2.0 |
ciprofloxacin | NT | NT | NT | 2 | — | — | 8 | — | — | 2 | — | — | 2 | — | — |
Moxifloxacin | 0.25 | 99.1 | 0.9 | 0.5 | 98.1 | 1.9 | 0.5 | 98.2 | 1.2 | 0.25 | 97.9 | 1.4 | 0.25 | 98.3 | 1.3 |
Cefatriaxone | 2 | 81.5 | 1.1 | 2 | 76.2 | 6.2 | 2 | 77.9 | 7.1 | 2 | 82.1 | 6.6 | 2 | 80.0 | 5.3 |
Cefepime | 2 | 76.1 | 1.4 | 4 | 46.6 | 14.1 | 4 | 62.6 | 19.7 | 2 | 72.4 | 6.6 | 2 | 66.0 | 10.0 |
Imipenem | 0.25 | 52.3 | 0.3 | 0.25 | 64.0 | 0.3 | 0.5 | 57.9 | 2.6 | 0.5 | 59.7 | 2.4 | 0.25 | 65.0 | 1.0 |
Meropenem | 0.5 | 42.6 | 4.3 | 1 | 48.8 | 11.1 | 1 | 57.4 | 24.1 | 1 | 63.1 | 13.4 | 1 | 48.7 | 12.0 |
Azithromycin | > 256 | 1.7 | 97.4 | > 256 | 0.3 | 98.1 | > 256 | 2.1 | 97.4 | > 256 | 2.8 | 96.2 | > 256 | 1.7 | 97.0 |
S, Susceptible rate (%); R, Resistant rate (%); ceftriaxone and cefepime were determined by non meningitis standard (susceptibility: ≤1 mg / L; resistance: ≥4 mg / L); NT, not detected; —, no criteria. |