In vitro activities of various piperacillin and sulbactam combinations against bacterial pathogens isolated from Intensive Care Units in Taiwan: SMART 2004 programme data

In Vitro Activity of Various Sulbactam Compounds and Piperacillin/Tazobactam against Clinical Isolates of Different Gram-Negative Bacteria

To provide direction for clinical application and pharmaceutical exploitation, the in vitro activity of sulbactam compounds and PIP/TAZ 8 : 1 against clinical isolates of Gram-negative bacteria (GNB, n = 976) was evaluated according to Clinical and Laboratory Standards Institute (CLSI) 2019. By minimal inhibitory concentrations (MICs), the resistance rate of all GNB to AMP/SBT 2 : 1 (56.9-100%) was significantly higher than other drugs, except the resistance rate of Acinetobacter baumannii (Aba, n = 204) to piperacillin/tazobactam (PIP/TAZ 8 : 1, 78.4%) which was close to it (76.5%). Additionally, the resistance rate of Aba to other compounds except AMP/SBT 2 : 1 differed greatly, but that of Klebsiella pneumonia (Kpn, n = 205) varied rarely. In addition, Escherichia coli (Eco, n = 204) and Kpn demonstrated low and high resistance rates, respectively. Compared with cefoperazone/sulbactam (CPZ/SBT 2 : 1), PIP/TAZ 8 : 1 had advantage in anti-Eco (RR = 0.5and OR = 2.17) and anti-Kpn activity (RR = 0.88and OR = 1.27), while its activity against Pseudomonas aeruginosa (Pae: n = 194, RR = 0.91, and OR = 1.12), Aba (RR = 1.31 and OR = 0.41), and other Enterobacteriaceae (other Ebc: n = 169, RR = 1.40, and OR = 0.62) was not better than CPZ/SBT 2 : 1. Although it had advantage against Eco (RR = 0.60 and OR = 1.78), Pae (RR = 0.67 and OR = 1.63), and Aba (RR = 0.70 and OR = 2.05), the inhibition effect of piperacillin/sulbactam (PIP/SBT 2 : 1) against Kpn (RR = 0.94 and OR = 1.12) and other Ebc was just similar with CPZ/SBT 2 : 1 (RR = 0.93 and OR = 1.10). Furthermore, the anti-Eco (RR = 0.70 and OR = 1.50), anti-Kpn (RR = 0.89 and OR = 1.24), and anti-Pae (RR = 0.74 and OR = 1.46) activities of ceftazidime/sulbactam (CAZ/SBT 1 : 1) had a weak advantage, while its activity against Aba (RR = 0.94 and OR = 1.15) and other Ebc (RR = 0.79 and OR = 1.36) was just close to CPZ/SBT 2 : 1. Moreover, the inhibitory effect of PIP/SBT 1 : 1 against all tested clinical species was more active than CPZ/SBT 2 : 1, while that of CAZ/SBT 2 : 1 against all species of bacteria analyzed was weaker than the controls.

Cefoperazone/sulbactam: New composites against multiresistant gram negative bacteria?

Sulbactam, a class A β-lactamase inhibitor, added to cefoperazone either at a fixed 8 mg/L level of sulbactam or at a level of fixed cefoperazone: sulbactam ratio (2:1) would constitute a combination form of cefoperazone/sulbactam, which has better activities against Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii than cefoperazone alone. Cefoperazone/sulbactam (1:1 or 1:2) has greater in-vitro activity against most multidrug-resistant organisms (ESBL- and AmpC-producing Enterobacteriaceae and carbapenem-resistant A. baumannii except for carbapenem-resistant P. aeruginosa) than a 2:1 ratio. However, increased sulbactam concentration may induce AmpC production. Besides, sulbactam concentration might not be readily achievable in serum if the susceptibility rates were defined by the breakpoints of higher sulbactam composites, such as ≤16/16 (1:1) or 16/32 (1:2) mg/L. Carbapenemases (KPC-, OXA-type enzymes and metallo-β-lactamases) can't be inhibited by sulbactam. Some in-vitro studies showed that increasing sulbactam composites of cefoperazone/sulbactam had no effect on carbapenem-resistant P. aeruginosa, suggesting the presence of carbapenemases or AmpC overproduction that could not be overcome by increasing sulbactam levels to recover cefoperazone activity. Sulbactam alone has good intrinsic activity against carbapenem-resistant Acinetobacter strains sometimes even in the presence of carbapenemase genes, suggesting unsteady levels of carbapenemases. In conclusion, appropriate composites of cefoperazone and β-lactamase inhibitor sulbactam may expand the clinical use if the pharmacokinetic optimization could be achieved in the human serum.

Susceptibility rates of clinically important bacteria collected from intensive care units against colistin, carbapenems, and other comparative agents: results from Surveillance of Multicenter Antimicrobial Resistance in Taiwan (SMART)

Objectives

This study aimed to determine the in vitro susceptibility of commonly encountered Gram-negative bacilli (GNB) recovered from patients admitted to intensive care units (ICUs) in Taiwan against colistin, carbapenems, and other comparative agents.

Methods

In total, 758 nonduplicate GNB isolates were obtained from clinical specimens of ICU patients at seven medical centers in 2016. Minimum inhibitory concentrations (MICs) were determined using the Vitek 2 susceptibility system. The reference broth-microdilution method was performed to determine MICs of colistin. Five main carbapenemase genes among carbapenem-non-susceptible GNB and mcr-1-mcr5 genes among colistin non-wild-type or -resistant isolates were determined.

Results

After exclusion 38 Proteus mirabilis and 13 Morganella morganii spp. among 361 Enterobacteriaceae isolates, 34 (9.4%) isolates were carbapenem-insusceptible, 91.1% (n=31) were colistin wild type, and three and one Klebsiella pneumoniae isolates carried bla _KPC and bla _OXA48-like, respectively. Carbapenem-insusceptible isolates were found in 23.4% (30 of 128) and 63.0% (87 of 138) of isolates of the Pseudomonas aeruginosa and Acinetobacter baumannii complex, respectively. mcr-1 was detected in two (1.8%) Enterobacter cloacae isolates. Very major errors between two methods of susceptibility to colistin were found in 1.5% of K. pneumoniae, 27.5% of E. cloacae, 4.7% of P. aeruginosa, and 10.1% of A. baumannii complex isolates.

Conclusion

In this study, 8.7% of Enterobacteriaceae isolates from ICUs were not susceptible to carbapenem, and bla _KPC and bla _OXA48-like were found among three and one carbapenem-insusceptible K. pneumoniae isolates, respectively. Colistin MICs determined by Vitek 2 were not reliable, especially for E. cloacae and A. baumannii complex isolates.

Appropriate composites of cefoperazone-sulbactam against multidrug-resistant organisms

Objectives

This study aims to assess the in vitro activity of different cefoperazone-sulbactam ratios against different multidrug-resistant organisms (MDROs).

Materials and methods

Minimum inhibitory concentrations (MICs) and susceptibility rates of cefoperazone, sulbactam and cefoperazone-sulbactam at fixed ratios of 2:1, 1:1 and 1:2 against 344 MDRO clinical isolates, including extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (n=58), ESBL-producing Klebsiella pneumoniae (n=58), carbapenem-resistant Enterobacteriaceae (n=57), carbapenem-resistant Pseudomonas aeruginosa (n=49) and carbapenem-resistant Acinetobacter baumannii (n=122), were measured.

Results

Combined treatment with sulbactam and cefoperazone resulted in decreased MIC₅₀ values across all MDROs, as well as decreases in most MIC₉₀ values, except for carbapenem-resistant Enterobacteriaceae and carbapenem-resistant P. aeruginosa (MIC₉₀ values remained >64 mg/L). Susceptibility rates of treatment with cefoperazone alone against all MDROs were much lower than that of cefoperazone-sulbactam combination (all P<0.05), except in carbapenem-resistant P. aeruginosa. Additionally, the susceptibility rate gradually increased as the ratio of cefoperazone-sulbactam was adjusted from 2:1 to 1:1 and to 1:2 for carbapenem-resistant Enterobacteriaceae, ESBL-producing K. pneumoniae and carbapenem-resistant A. baumannii. There were no significant ratio-dependent changes in susceptibility rates with cefoperazone-sulbactam in carbapenem-resistant P. aeruginosa.

Conclusion

Adding sulbactam enhances cefoperazone activity against most MDROs excluding carbapenem-resistant P. aeruginosa, and the activity of cefoperazone-sulbactam against these MDROs is greatest at a ratio of 1:2, followed by ratios of 1:1 and 2:1.

Simultaneous spectrophotometric determination of ceftazidime and sulbactam using multivariate calibration methods

The simultaneous spectrophotometric determination of ceftazidime (CTZ) and sulbactam (SBT) in the presence of the overlapping spectra were accomplished with the partial least squares (PLS) and genetic algorithm-partial least square (GA-PLS) approaches.

Pharmacist interventions on antibiotic use in inpatients with respiratory tract infections in a Chinese hospital

OBJECTIVE

To evaluate the impact of pharmacist interventions on antibiotic use in inpatients with respiratory tract infections in a tertiary hospital in China.

METHOD

Two independent respiratory wards were randomized into control and intervention group. Between July 2009 and April 2010, all inpatients diagnosed with respiratory tract infections were enrolled. Pharmacist interventions were performed on the physicians in the intervention group. The total cost of hospitalization, cost of antibiotics, length of hospital stay and the scores of 6 items of inappropriate antibiotic use (including indication, choice, dosage, dosing schedule, duration and conversion) were analyzed.

RESULTS

The total costs of hospitalization in the intervention group were significant lower compared to the control group ($1442.3 ± 684.9 vs. $1729.6 ± 773.7, P < 0.001), as well as the cost of antibiotics ($832.0 ± 373.0 vs. $943.9 ± 412.0, P = 0.01), and the patients required shorter length of hospital stay (14.2 ± 6.2 vs. 15.8 ± 6.0 days, P = 0.03). The scores with respect to the 6 items of inappropriate antibiotic use were all lower in the intervention group than in the control group.

CONCLUSIONS

Pharmacist interventions, interacted directly with the physicians at ward level, could play an important role in optimizing antibiotic use, thus lead to the reduction in patients' length of hospital stay and health care cost.