Gut 1997; 40: 526-530

Influence of changes in pancreatic tissuemorphology and capillary blood flow on antibiotictissue concentrations in the pancreas during theprogression of acute pancreatitis

Th Foitzik, H G Hotz, M Kinzig, F Sorgel, H J Buhr

AbstractBackground-The ability of an antibioticto reach bactericidal concentrations intissue depends on numerous factors in-cluding tissue composition and regionalperfusion. Although necrotising pancrea-titis is characterised by progression ofpancreatic necrosis over at least 96 hoursand microcirculatory alterations, theimpact of these changes on the concen-tration of antibiotics in the pancreas hasnot yet been investigated.Aim-To determine and compare pan-creatic tissue concentrations ofimipenemand cefotaxime at different stages of acutenecrotising pancreatitis in an animalmodel that has been shown to mim cclosely the pathomorphological and bac-teriological features of severe humanpancreatitis.Method-Acute necrotising pancreatitiswas induced in rats by a standardisedintraductal infusion of glycodeoxycholicacid and intravenous cerulein. Six hours(n=16) and 48 hours (n=16) after inductionof pancreatitis, the animals were ran-domised for intravenous therapy witheither imipenem or cefotaxime. Fifteenminutes after injection of the antibiotic,the animals were killed. Blood and thehead of the pancreas were collected fordetermining imipenem or cefotaxime inserum and tissue; the splenic portion ofthe pancreas was prepared for histologicalexamination. In an additional set ofidentically treated aniimals, pancreaticcapillary blood flow (PCBF) was assessedby intravital microscopy before inductionofacute necrotising pancreatitis and at thetime of antibiotic therapy.Results-Imipenem accumulates in thepancreas in the initial phase of acutenecrotising pancreatitis characterised bypronounced oedema and decreasedPCBF, and tends to decrease with resol-ution ofthe oedema and the progression ofacinar cell necrosis in the later course ofthe disease. Concentrations of cefotaximeare low in oedematous pancreatic tissueearly after induction of acute necrotisingpancreatitis and increase with the resol-ution of oedema and normalisation ofPCBF.Conclusions-Concentrations of anti-biotics in the pancreas vary in acutenecrotising pancreatitis, depending on

changes in pancreatic tissue morphologyand capillary blood flow. This suggeststhat antibiotic tissue concentrations maynot be consistent from one agent toanother and that efficacy of antibiotics inacute pancreatitis cannot be estimatedsolely on the basis of their pharma-cological and microbiological properties.(Gut 1997; 40: 526-530)

Keywords: acute pancreatitis, necrosis, capillary bloodflow (microcirculation), antibiotic therapy, imipenem,cefotaxime.

Secondary infection of pancreatic necrosis ispresently the major cause of morbidity andmortality in acute necrotising pancreatitis.'-3Recent pharmacological and bacteriologicalstudies have identified antibiotics which, unlikepreviously used drugs, reach bactericidal con-centrations in the pancreas and cover thosebacteria which usually infect pancreaticnecrosis.4 5 Imipenem, one of these antibiotics,has been shown to reduce infectious compli-cations in acute necrotising pancreatitis whenstarted early after the onset of the disease.6Clinical experience has, however, questionedthe advantage of imipenem over other anti-biotics once the start of antibiotic treatment isdelayed - for example, in patients who areadmitted several days after the onset of thedisease. Furthermore, it has been shown thatimipenem concentrations remain inadequatein frank pancreatic necrosis whereas other anti-biotics seem to penetrate better into necrotictissue.7 Against this background, we speculatedthat antibiotic concentrations in pancreatictissue may vary depending on the evolution ofthe disease. To test this hypothesis, wemeasured pancreatic tissue concentrations ofimipenem at different stages of acute necro-tising pancreatitis (early v late) in an improvedanimal model which has been shown to mimicclosely the morphological and bacteriologicalfeatures of severe human pancreatitis.8 9 Toelucidate whether changes in tissue geometryand regional perfusion occurring in the courseof the disease may interfere with the pattern ofantibiotic tissue distribution, we determinedthe amount of necrosis and oedema in thepancreas as well as pancreatic capillary bloodflow at the time of antibiotic treatment. Finally,we compared the values obtained for imipenemwith those of cefotaxime, another antibioticwidely used in acute pancreatitis.

Department ofSurgery, FreieUniversitdit BerlinTh FoitzikH G HotzH J Buhr

Institute forBiomedical andPharmaceuticalResearch, Ntlrnberg,GermanyM KinzigF SorgelCorrespondence to:Dr Thomas Foitzik,Abt f Allgemein-, Gefai-undThoraxchirurgie, KlinikumBenjamin Franklin, FreieUniversitat Berlin,Hindenburgdamm 30,D- 12 200 Berlin.

Accepted for publication28 November 1996

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Antibiotics in acute pancreatitis

MethodsAll experiments were conducted in accordancewith the national guidelines for animal care.After an overnight fast, male Sprague-Dawleyrats (body weight 310-390 g) were anaesthe-tised with intraperitoneal pentobarbitone (20mg/kg) and ketamine (40 mg/kg). Polyethylenecatheters (inner diameter 0-5 mm) wereinserted into the right jugular vein and the leftcarotid artery, subcutaneously tunnelled to theneck, and advanced through a steel tetherwhich allowed for blood sampling and intra-venous access in the unrestrained animals. Aspreviously described,8 acute necrotising pan-creatitis was induced by a standardised retro-grade infusion of 0 5 ml 10 mM glycodeoxy-cholic acid (GDOC; Sigma, St Louis, MO,USA) into the biliopancreatic duct for 10minutes, followed by a continuous intravenousinfusion of 5 pug/kg/h cerulein (CAE; Farmi-talia, Freiburg, Germany) over six hours. At sixhours (n=16) and at 48 hours after inductionof pancreatitis (n= 16), the animals wererandomised for an intravenous injection ofeither 13 mg/kg imipenem or 33 mg/kg cefo-taxime. Animals without pancreatitis treatedwith the same doses of imipenem and cefo-taxime served as controls. Fifteen minutes afterinjection of the antibiotic, blood was drawn todetermine imipenem and cefotaxime in serum;then the animals were killed by an intra-arterialinjection of pentobarbitone (200 mg/kg). Atnecropsy, the head of the pancreas washarvested for determination of imipenem andcefotaxime in tissue. All samples were immedi-ately frozen in liquid nitrogen and stored at-80°C. The splenic portion of the pancreas wasused for histological examination and deter-mination of the wet:dry ratio.

HISTOLOGY

Pancreatic oedema and acinar cell necrosiswere evaluated and scored according to pre-viously described criteria.8 The pancreaticwater content was determined by calculatingthe ratio between the initial weight of thespecimens (wet weight) and their weight afterincubation at 2 10°C for 12 hours (dry weight).

ANTIBIOTIC CONCENTRATIONS IN SERUM AND

TISSUE

After completion of the experiments, blood andpancreatic tissue samples were thawed, vigor-ously mixed, and centrifuged for five minutesat 3600 rpm. To determine imipenem, de-proteinisation was carried out by ultrafiltration(Amicon, Micropartitionssystem MPS-1) afteradding the internal standard. An aliquot of thefiltrate (180 ,ul) was injected into a high per-formance liquid chromatography (HPLC)system. Quantification of imipenem was basedon chromatographic separation on a reversedphase column (Spherisorb ODS II) using amixture of 0-6 M NaH2PO4 and acetonitrile(98-5/1 -5; v/v) as the mobile phase. The pH wasadjusted to 6-55. Detection was achieved witha GAT-LCD 501 detector at 300 nm. Theretention times of imipenem and the internal

standard were 13 and 18 minutes respectively.Turbochrom software (version 3-2, 1991; PENelson, Cupertino, CA, USA) was used forevaluating the chromatograms. To determinecefotaxime, 100 R1 of the samples werestabilised with sodium acetate buffer (100 [LI)and deproteinised by addition of 400 pI ace-tonitrile containing an internal standard. Aftermixing and centrifugation at 3600 rpm, theacetonitrile was removed by extraction with 1ml dichloromethane. After centrifugation at3600 rpm for five minutes, 120 pI of theaqueous phase were injected into the HPLCsystem. The chromatographic separation wasperformed on a Spherisorb ODS II, 5 ,um(125X4 6 mm internal diameter) column usingan isocratic solvent system consisting of 0 05 Mpotassium dihydrogen phosphate buffer andacetonitrile containing 5 mM tetrahexyl ammo-nium chloride (83/17: v/v). The retention timesof cefotaxime and the internal standard wereeight and 7-5 minutes respectively. The eluentwas monitored by UV detection with a wave-length of 254 nm, and Turbochrom software(see above) was used for evaluating the chro-matograms. To evaluate regional pancreaticperfusion, the number of perfused capillariesand capillary pancreatic blood flow (PCBF) atthe time of antibiotic treatment were determinedin another set of identically treated animals byintravital microscopy using the equipment andtechnique previously described.'° 1' Six and 48hours after induction of acute necrotising pan-creatitis, animals were reanaesthetised, the pan-creas was exteriorised, placed in an immersionchamber with Ringer's lactate maintained at37°C, and positioned under a fluorescencemicroscope (Leitz, Wetzlar, Germany) with aheat protection and an excitation filter (450-490nm). At that point, the animals received anintravenous injection of 0 5 mi/kg erythrocyteslabelled with fluorescein isothiocyanate (FITC;Sigma, Deisenhofen, Germany). After astabilisation period of 15 minutes, threerandomly chosen regions in the head of thepancreas (325-400 ,um) were recorded for offline analysis. In each animal, blood flow wascalculated in 30-40 consecutively recordedcapillaries from the concentration of fluorescenterythrocytes per unit of arterial blood at the timeof the recording, the capillary packed cellvolume, and the number of FITC labellederythrocytes passing through the respectivevessel.'0 Capillary stasis was ascribed if therewere no labelled erythrocytes passing throughthe capillary within the recording time (three tofive minutes). Measurements in Ringer's lactate-pretreated animals without pancreatitis served asadditional controls. Cardiorespiratory moni-toring included continuous measurements of themean arterial pressure and heart rate as well asrepeated control of the arterial blood gases andcomparison ofthe packed cell volume before andafter intravital microscopic examination toensure stability of the preparation. Becausesystemic circulatory derangement may influencethe distribution and regional concentration ofthe antibiotic, animals with unstable bloodpressure (MAP <90 mm Hg) were excludedfrom analysis.

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Concentrations (mean (SEM)) of imipenem andcefotaxime in serum and pancreatic tissue before (O hrs)and after (six and 48 hrs) induction ofpancreatitis

Itnipenem Cefotaxine

Tinme Serumtz Tissue Seruml Tissue(hr) (Ag/itsl) (Ug/g) (Ag/nil) (,ug/g)

0 26 (2) 1 8 (04) 56 (3) 100 (1-6)6 29 (2) 13 2 (0-6)* 47 (5) 2 1 (0 4)*48 27 (2) 10-8 (0 9)* 50 (5) 6-8 (1-3)**

*p<0.05 z 0 hr; **p<0.05 z 6 hr.

STATISTICSAll results are expressed as mean (SEM).Variables were tested for group differences withStudent's t test. A p value <0 05 was con-sidered significant.

ResultsCompared with healthy control animals, pan-creatic tissue concentrations of imipenem weresignificantly increased six hours and 48 hoursafter induction of acute necrotising pancrea-titis. Six hour values tended to be higher than48 hour values (p=0054). Tissue concen-trations of cefotaxime measured in animals sixhours after induction of acute necrotising pan-creatitis were significantly lower than those ofhealthy control animals; 48 hours after pan-creatitis induction they had significantlyincreased and did not differ from baselinevalues. No significant differences were found inserum concentrations of imipenem or cefo-taxime at different time points (Table). Like-wise, the ratio between the tissue and serumconcentrations of imipenem was significantlyincreased in rats with six and 48 hours of acutenecrotising pancreatitis (compared with theratios determined in healthy control animals),whereas for cefotaxime it was decreased sixhours after induction of acute necrotising pan-creatitis, and significantly increased after 48hours, reaching values comparable with thoseobtained in rats without pancreatitis (Fig 1).Histology showed pronounced interstitialoedema and moderate acinar cell necrosis sixhours after induction of acute necrotising pan-creatitis; at 48 hours oedema had significantlydeclined and necrosis had significantly in-creased (Fig 2). In accordance with themacroscopic and histological findings, thewet:dry weight ratio of pancreatic tissue wasincreased almost threefold six hours afterinduction of acute necrotising pancreatitis.With resolution of the oedema, the water

WE OedemaNecrosis

* 3C:

0

C) 1-

0

0 hr 6 hr 48 hr

Figure 2: Pancreatic oedema and acinar cell necrosis before(O hr) and 6 hr and 48 hr after induction ofpancreatitls.

content significantly decreased until 48 hoursbut was still increased compared with normalpancreatic tissue (Fig 3). The PCBF wasreduced six hours after induction of acutenecrotising pancreatitis and had returnedalmost to baseline values by 48 hours (Fig 4).

Discussion

CLINICAL BACKGROUND

Recent pharmacological and microbiologicalstudies have suggested that cephalosporines,quinolones, imipenem, and metronidazole areadequate to prevent and treat pancreatic in-fections, whereas aminoglycosides and ampi-cillin used in earlier studies did not alwaysreach bactericidal concentrations in the pan-creas or cover the bacteria isolated from theinfected pancreatic tissue. 12 14 Subsequentclinical trials confirmed that prophylactictreatment with imipenem or cefuroxime

7

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O hr 6 hr 48 hr

Figure 3: Weight:dry weight ratio ofpancreatic tissue before(O hr) and 6 hr and 48 hr after induction ofpancreatitis.

2.5

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*4 0.5 - CEF04-

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0 hr

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Figure 1: Tissue:serum ratio of imipenemz (IMI) andcefotaxime (CEF) before (O hr) and 6 hr and 48 hr afterInductlon ofpancreatitis.

O hr 6 hr 48 hr

Figure 4: Capillary pancreatic bloodflow (CPBF) before(O hr) and 6 hr and 48 hr after induction ofpantcreatitis.

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Antibiotics in acute pancreatitis

significantly reduced pancreatic infections andseptic complications in patients with acutenecrotising pancreatitis compared with thosewho received antibiotics only when infectionwas clinically apparent.6 15 Thus it has beenrecommended that patients with acute necro-tising pancreatitis should be prophylacticallygiven antibiotics with appropriate pharma-cokinetic properties. The effects of antibioticsin acute necrotising pancreatitis are, however,poorly understood, and the data reported arebased on very few samples of patients withvarious forms of pancreatic diseases.5 7 There-fore, it was the aim of this study to elucidatefurther factors which may influence antibiotictissue concentrations in the course of acutepancreatitis - namely, the extent of acinarcell necrosis and pancreatic capillary bloodflow.

METHODOLOGICAL ASPECTSWe have recently developed and characterisedan improved model of acute necrotising pan-creatitis in the rat which closely mimics themorphological and bacteriological features ofsevere human pancreatitis.8 9 Having shown itssuitability for studying both the patho-physiology of bacterial infection of the pan-creas in acute necrotising pancreatitis andantimicrobial strategies for the prevention ofbacterial contamination ofpancreatic tissue,9 16

we now used this model to evaluate further theeffect ofmorphological alterations and changesin capillary pancreatic perfusion on antibiotictissue concentrations. Antibiotics were firstgiven six hours after the start of pancreatitisinduction, which represents the early stage ofthe disease, characterised by pronouncedpancreatic oedema, initial acinar cell necro-sis, and microcirculatory derangement. Thesecond time point for measurements waschosen at 48 hours after induction when pan-creatic necrosis was fully developed. Because ithas been shown that pharmacological charac-teristics of the antibiotic (for example, molecu-lar weight, structure, polarity, pK, ionisation,lipid solubility) affect their ability to penetrateand accumulate in tissue,17-20 we comparedtissue concentrations of two different drugs(imipenem and cefotaxime,) which are bothpharmacologically well characterised andwidely used for antibiotic treatment in acutenecrotising pancreatitis.517 21-27 Doses of anti-biotics used in the current experiments wereadopted from previous studies in small rodentsand this model of acute necrotising pancrea-titis,9 and additional pilot studies had beenperformed to assure that the 15 minute periodbetween the injection of the drug and tissuecollection was sufficient for the antibiotics topenetrate into the pancreas. Determination ofthe serum and tissue concentrations of theantibiotics were performed by establishedmethods - namely, chromatographic separ-ation. The concentrations in the pancreas weremeasured in tissue homogenates, which doesnot allow for conclusions on the distribution ofthe drug within the different tissue compart-ments. Because of the high vulnerability of the

pancreas, it was not possible to retrieve extra-cellular pancreatic tissue fluid - for examle, bya thread implanted into the pancreas at thetime of pancreatitis induction or by soakingfluid on to paper discs after removal of thecapsule at the time of necropsy - as can beperformed in healthy muscle.25 Therefore, wemeasured the antibiotic tissue concentration inone portion of the pancreatic specimen anddetermined the wet:dry weight ratio and thedegree and extent of oedema and acinar cellnecrosis in the other half. This seemed to bea reasonable approach as the model ischaracterised by uniform morphologicalchanges throughout the entire pancreas.8

INTERPRETATION OF RESULTSSerum concentrations of imipenem and cefo-taxime measured in healthy rats and animalswith acute necrotising pancreatitis six and 48hours after induction did not significantlydiffer. Imipenem concentrations in the in-flamed pancreas exceeded those in normalpancreatic tissue. This has also been found byother investigators.7 It may in part be due tothe nature of the pancreas as an excretoryorgan and the use of cerulein for pancreatitisinduction, which is highly stimulatory to theexocrine pancreas. After 48 hours, imipenemtissue concentrations were notably lower thanafter six hours (although not significant;p=0054) but still higher than the minimuminhibitory concentrations for the organismsusually isolated from infected pancreatic tissuein this model of acute necrotising pancreatitisin the rat as well as in severe human pancrea-titis.7 Antibiotic tissue concentrations seemedto correlate with the degree of oedema, whichmay suggest that imipenem accumulated in therelatively small volume of interstitial fluid. Thisis in accordance with data on the rat granulomapouch, which shows high concentrations ofimipenem in the inflammatory exudate and atthe site of local inflammation (principallyoedema).22 23 It also corresponds with themeasurements in resected pancreatic tissue inhuman acute necrotising pancreatitis, wherethere is an accumulation of imipenem,especially in perinecrotic (oedematous) tissue.7Decreasing concentrations of imipenem withresolution of oedema and manifestation ofnecrosis on the other hand parallel thesefindings and suggest that imipenem, which hasa good water solubility and moderate lipo-solubility, may not freely penetrate into theacinar cells. Again, this is in accordance withthe findings of Bassi et al7 that imipenem didnot always reach sufficient concentrations innecrotic pancreatic tissue. Accumulation in theinterstitial space early in acute necrotising pan-creatitis (when the pancreas is not yet infected)may, however, be an advantage rather than adisadvantage because the bacteria are thoughtto arrive in the pancreas through the sameroute, penetrating from the extracellular spaceinto the cells.17 18 Another advantage of imi-penem is that it reaches high pancreatic tissueconcentrations despite significantly decreasedpancreatic capillary blood flow. Experiments in

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which we increased PCBF by isovolaemichaemodilution with dextran failed to improvesignificantly the tissue concentration of imi-penem, suggesting the accumulation of thisspecific antibiotic in the pancreas does notdepend on an intact regional perfusion.28 Bycontrast, pancreatic tissue concentrations ofcefotaxime remained inadequately low early inacute necrotising pancreatitis and only reachedminimum inhibitory concentrations after 48hours when oedema had decreased and PCBFhad returned to almost normal values. Lowpancreatic tissue concentrations (in thepresence of high serum concentrations) wouldexplain our previous finding that cefotaximedid not prevent early pancreatic infection (butprotected the kidney).'6 Corresponding valuesof PCBF and cefotaxime tissue concentrationsfound in healthy rats and animals with acutenecrotising pancreatitis at 48 hours, despitesignificant morphological differences, suggestthat cefotaxime, unlike imipenem, demandssufficient regional perfusion to reach the pan-creas in adequate concentrations. This hy-pothesis was underlined by experimentsshowing that tissue concentrations of cefo-taxime could be improved by enhancement ofPCBF (data not published). The dissimilarimpact of pancreatic microcirculation on thetissue concentration of imipenem and cefo-taxime would also explain why those differ-ences were more striking in our experimentthan in the study of Buchler et al,5 in whichmeasurements were performed in a hetero-geneous group of patients with pancreaticneoplasm, chronic and acute pancreatitis (at alater stage) in which pancreatic perfusion is notcompromised as much as in early severe acutepancreatitis. Although the experimental designdid not permit firm conclusions on the pathwayby which the antibiotics reached the necroticfoci, our results clearly indicate (1) thatchanges in PCBF and morphology occurring inthe course of acute necrotising pancreatitisinfluence the antibiotic tissue concentrationsand (2) that tissue concentrations may not beconsistent at any given time point and from oneantibiotic to another. Therefore, efficacy ofantibiotic treatment in acute pancreatitiscannot be estimated solely on the basis of invitro pharmacological and microbiologicalstudies, but requires evaluation in vivo. Morework in this field is necessary to optimiseantibiotic therapy, which presently is the besttool for futher improving the outcome of thislife threatening disease. Preferably, thesestudies should be performed as controlledclinical trials. As setting up clinical studies is,however, limited in acute necrotising pancrea-titis due to the paucity of severe cases in anyone institution, the great variability in theclinical course of the disease, and the invasive-ness of procedures for obtaining pancreaticspecimens, further animal studies are required.The present study shows that data obtainedfrom these types of experiments can provideinformation of clinical relevance provided thatthe animal model and the study design closelymimic the features and the course of severehuman pancreatitis.

This work was presented in part at the Annual Meeting of theAmerican Pancreatic Association, Chicago, November 1995.

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3 Widdison AL, Karanja ND. Pancreatic infection compli-cating acute pancreatitis [review]. Br 7 Surg 1993; 80:148-54.

4 Beger HG, Bittner R, Block S, Buchler M. Bacterial con-tammation of pancreatic necrosis. Gastroenterology 1986;91: 433-8.

5 BuchlerM, Malfertheiner P, Friess H, Isenmann R, Vanek E,Grimm H, et al. Human pancreatic tissue concentrationof bactericidal antibiotics. Gastroenterology 1992; 103:1902-8.

6 Pederzoli P, Bassi C, Vesentini S, Campedelli A, Pederozoli P.A randomized multicenter clinical trial of antibioticprophylaxis of septic complications in acute necrotizingpancreatitis with imipenem. Surgical Gynecology andObstetrics 1993; 176: 480-3.

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9 FoitzikT, MithoferK, Ferraro MJ, Fernandez-del Castillo CLewandrowski KB, Rattner DW, Warshaw AL. The timecourse of bacterial infection of the pancreas and itsrelation to disease severity in a rodent model of acutenecrotizing pancreatitis. Ann Surg 1994; 229: 193-8.

10 Mithofer K, Schmidt J, GebhardMM, Buhr HJ, Herfarth C,Klar E. Measurement of blood flow in pancreaticexchange capillaries with FITC-labelled erythrocytes.Microvas Res 1995; 49: 33-48.

11 Hotz HG, Schmidt J, Ryschich EW, Foitzik T, Buhr HJ,Warshaw AL, et al. Isovolemic hemodilution with dextranprevents contrast medium induced impairment of pan-creatic microcirculation in necrotizing pancreatitis in therat. Am_J Surg 1995; 169: 161-6.

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16 FoitzikT,Femandez-del CastilloC, FerraroMJ, RattnerDW,Warshaw AL. Pathogenesis and prevention of early pan-creatic infection in experimental acute necrotizing pan-creatitis.Ann Surg 1995; 222: 179-85.

17 Bergan T. Pharmacokinetics of tissue penetration of anti-biotics. Rev Infect Dis 1981; 3: 45-66.

18 Barza M. Principles of tissue penetration of antibiotics. JfAntimicrob Chemother 1981; 8 (suppl C): 7-28.

19 Ryan DM, Cars 0, Hoffstedt B. The use of antibiotic serumlevels to predict concentrations in tissues. Scand J7 InfectDis 1986; 18: 381-8.

20 Adam D. Tissue concentrations of cephalosporine anti-biotics in man. In: Van der Waaij D, Verhoef J, eds. Newcriteria for antimicrobial therapy. Amsterdam: ExcerptaMedica, 1979: 174-83.

21 Papenburg R, Vallee F, LeBel M, Brown R, Fleiszer D.Tissue penetration of cefotaxime in normal pigs and pigswith hemorrhagic pancreatitis. J Antimicrob Chemother1990; 26 (suppl A): 11-4.

22 Hashizume T, Okumoto Y, Ogashiwa M, Shimano K.Penetration of imipenem and other antibiotics into in-flammatory exudate and their efficacy in pseudomonasinfection inthe rat granuloma pouch model. _AntimicrobChemother 1987; 20: 413-6.

23 Brauer E, Gorbach S, Davey P. Comparative study ofclindamycin, imipenem, oxacillin and vancomycin in theinfected granuloma pouch model. _Antimicrob Chemother1989;23: 891-8.

24 Lankisch PG, Klesel N, Seeger K, Siedel G, Wmckler K.Penetration of cefotaxime into the pancreas. Z Gastro-enterol 1983; 21: 601-3.

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27 Walstad RA, Hellum KB, Blika S, Dale LG, Fredriksen T,Myhre KI, Spencer GR. Pharmacokinteics and tissuepenetration of ceftazidime. JfAntimicrob Chemother 1983;12 (suppl A): 275-82.

28 FoitzikT,HotzHG,KinzigM,S6rgelF,KlarE,WarshawAL,Buhr HJ. Improvement of pancreatic capillary blood flowdoes not augment the pancreatic tissue concentration ofimipenem in acute experimental pancreatitis. Eur 3Surg1996; 28: 395-401.

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