Cloxacillin

Antibiotic usage was calculated by means of the treatment frequency TF per half year, which relates the number of used daily doses to the farm size, i.e.
$\text{TF}=\frac{\text{nUDD}}{\text{farm size }}.$
[12 (link), 13 (link)]. The information needed to calculate the number of used daily doses (nUDD = number of days treated × number of active substances applied × number of animals treated) is included in the ADFs directly, so the number of used daily dose does not need to be estimated with an average animal weight or other surrogates. The population size is defined as the average number of housed animals per age class documented by the farmer in the entire QS system. To evaluate the treatment frequency in sucklers, the population size is linked to the average number of sows housed.
The definition of TF follows the concept of the (cumulative) incidence in epidemiology by relating events (here nUDD) to a (fixed) population size (here the farm size). As nUDD may be re-arranged
$\begin{array}{ll}\text{nUDD}\hfill & =\frac{\text{amount\hspace{0.17em}used}}{\text{animal \hspace{0.17em}weight}\times \text{UDD }}=\frac{\text{amount\hspace{0.17em}used}}{\text{animal\hspace{0.17em}weight}\times \frac{\text{amount\hspace{0.17em}used}}{\text{animals\hspace{0.17em}treated}\times \text{animal\hspace{0.17em}weight}\times \text{days\hspace{0.17em}treated}}}\hfill \\ \hfill & =\text{\hspace{0.17em}animals\hspace{0.17em}treated}\times \text{days\hspace{0.17em}treated}\hfill \end{array}$
TF describes the number of days all animals within the stock are treated in average. This is the same as Timmermanns et al. [20 (link)], Persoons et al. [21 (link)] and others are calculating by introducing average body weights to the stock treated.
This is in a slight contrast to other definitions, which follow the concept of an incidence density, where nUDD is divided by a farm-individual time-at-risk.
Pharmaceuticals or treatments containing two or more different active substances are entered into the calculation with a value of two, or more. The combination of sulfonamides with trimethoprim, ampicillin and cloxacillin, benzylpenicillin-benzathin and benzylpenicillin-procain, as well as benzylpenicillin-kalium and benzylpenicillin-procain are interpreted as one active substance.
The treatment frequency is calculated for every age group per national Farm-ID and half year as its whole as well as for every active substance separately. To illustrate the distribution of treatment frequencies, an empirical density function was approximated (restricted to treatment frequencies smaller than or equal to 100) by means of a negative binomial model.
The percentage of the treatment frequency of an active substance per total treatment is calculated using a unilateral alpha trimmed data set (1%) for a more robust statistical inference [22 ]. To this end, the total treatment frequency and the treatment frequency per active substance are summed up. From the total treatment frequency, the percentage of each active substance is calculated [23 (link)]. This calculation is performed separately for each age class and half year.
All ADF information and basic farm data were linked by national Farm-ID and evaluated with SAS^®, version 9.3 TS level 1M2 (SAS Institute Inc., Cary, NC, United States).

The EUCAST database lacks information on the MIC distribution of flucloxacillin for MSSA [Eucast]. Therefore, PK/PD target attainment simulations were performed using the epidemiological cut-off (ECOFF) value of cloxacillin for MSSA (0.5 mg/L) [30 ]. It has been reported that MIC distributions of cloxacillin and flucloxacillin for MSSA are similar [31 (link)]. Monte Carlo dosing simulations were performed to predict target attainment at steady state in 1000 virtual patients. Continuous and intermittent dosing regimens were applied for daily doses ranging from 4 to 24 g [32 (link), 33 (link)], using MicLab 2.70 (Medimatics, Maastricht, The Netherlands) [34 (link), 35 (link)]. PK/PD targets were set at ƒT_>MIC ≥ 50%, ƒT_>MIC = 100%, ƒT_>4xMIC ≥ 50%, and ƒT_>4xMIC = 100%. Population PK parameters were assumed to be log-normally distributed (mean ± standard deviation [SD]). Intermittent flucloxacillin infusion duration was set at 0.5 h. MIC range was 0–4 mg/L, with MIC bins set to 0.0625 mg/L. The confidence interval for the distribution analysis was set at 95%. Covariance between model parameters was assumed to be absent.

Obtained isolates were tested for antimicrobial resistance with the disk diffusion method, as described by CLSI [29 ]. Briefly, a suspension equivalent to 0.5 McFarland turbidity was prepared in sterile saline water for each isolate, and it was inoculated onto Mueller–Hinton agar (MH) (Thermo Fisher Diagnostics, Milan, Italy) plates with a sterile cotton swab. A maxim of 6 antimicrobial disks were placed in each plate and, subsequently, MH plates were incubated at 35 °C for 16–20 h. The antimicrobials disks (Thermo Fisher Diagnostics, Milan, Italy) tested were as follows: ampicillin (10 µg), amoxicillin-clavulanate (20/10 μg), cefoxitin (30 μg), cefotaxime (30 μg), ceftiofur (30 μg), Imipenem (10 μg), ertapenem (10 μg), aztreonam (30 μg), chloramphenicol (30 μg), tetracycline (30 μg), enrofloxacin (5 μg), ciprofloxacin (5 μg), gentamicin (10 μg), amikacin (30 μg), and trimethoprim-sulfamethoxazole (1.25/23.75 μg). Results were interpreted in accordance to CLSI guidelines [30 ,31 ].
Enterobacteriaceae isolates, including Salmonella, which were resistant or intermediate to Imipenem or ertapenem in the disk diffusion test, were evaluated for Carbapenemase production with the Modified Carbapenem Inactivation Methods (mCIM) and EDTA-modified Carbapenem Inactivation Methods (eCIM) [31 ]. The same isolates were tested for bla_NDM, bla_KPC, bla_OXA-48, bla_IMP, and bla_VIM gene presence too. Primers and PCR protocols, previously described by other authors, were adopted [32 (link)].
Enterobacteriaceae, including Salmonella, showing, in the disk diffusion test, an inhibition zone diameter lower than 27 mm for cefotaxime and/or aztreonam, were tested for ESBL production, as reported by CLSI [31 ]. Furthermore, the occurrence of genes bla_TEM, bla_SHV, and bla_CTX-M were evaluated with primers and PCR protocols, as described in the literature [33 (link),34 (link)].
Enterobacteriaceae, including Salmonella, which were resistant or intermediate to cefoxitin, were tested for AmpC β-lactamases using a combination disk test with cefotaxime (30 μg), ceftazidime(30 μg), and cloxacillin (500 μg) [35 (link)]. These isolates were further tested by PCR for bla_CMY-1 and bla_CMY-2 gene presence, as previously reported [34 (link)].
Positive PCR products were sequenced (BMR Genomics, Padova, Italy); obtained sequences were analyzed using BioEdit and compared with gene banks database using Basic Local Alignment Search Tool (BLAST) and FASTA (https://www.ebi.ac.uk/Tools/sss/fasta/) (accession date 7 October 2022).

As part of the prophylaxis based on the hospital formulary, recipients received meropenem (3 × 1 g), amikacin (15 mg/kg), and cloxacillin (4 × 1 g). Fluconazole (intravenous in 1st–3rd postoperative days), itraconazole (orally or through a probe), and voriconazole (orally and intravenous in CF patients or with history of Aspergillus fumigatus infection) were used as antifungal agents. Valganciclovir or ganciclovir were used as drugs active against cytomegalovirus. Topically, three agents were applied: amphotericin B (inhalation, 2 × 15 mg), nystatin (oral mucosa 4 × 1 mL suspension), and mupirocin (nasal vestibule twice a day). The basic set was used for a minimum of three days. It was modified depending on the recipient’s historical culture results or after obtaining the results of current microbiological tests. The first doses of antibiotics were administered intravenously in the operating theater before the beginning of the procedure. Antifungal drugs were introduced on the first postoperative day while antiviral agents were introduced within 10 days after the procedure.