Platelet-mediated bleeding caused by broad-spectrum penicillins

Platelet Dysfunction and Intracerebral Hemorrhage in a Patient Treated with Empiric Piperacillin-Tazobactam in the Neurocritical Care Unit

BACKGROUND

Piperacillin-tazobactam is common empiric antibiotic therapy. Hematologic laboratory test abnormalities were documented but rare in premarketing studies, and whether these alterations are of clinical significance has been studied little. Very few cases of piperacillin-induced bleeding, thrombocytopenia, or both have been reported; aberrations in platelet function have not been implicated.

CASE DESCRIPTION

A 55-year old Vietnamese man with hypertension presented for treatment of an Intracranial hemorrhage. Platelet function assays (PFAs) at the time of external ventricular drain and quad-lumen bolt placement were normal, and imaging showed no hemorrhage after placement. The patient was later started on empiric piperacillin-tazobactam due to high suspicion for aspiration pneumonia. After removal of the quad-lumen bolt and external ventricular drain on separate days, both follow-up computed tomography scans showed new hematomas in the devices' tracts, with significant intraventricular hemorrhage. Repeat PFAs were abnormally prolonged, representing a distinct change from baseline. A trend toward normalization of PFAs was observed 6 hours after discontinuation of piperacillin-tazobactam with progression toward baseline thereafter.

CONCLUSIONS

This is unique in that the significant bleeding that occurred was attributable to platelet dysfunction rather than thrombocytopenia. This is the first reported case of intracranial (periprocedural) hemorrhage potentially related to piperacillin-tazobactam; further research into this drug's impact upon qualitative platelet function is needed.

Haemostasis in chronic kidney disease

The coagulation system has gained much interest again as new anticoagulatory substances have been introduced into clinical practice. Especially patients with renal failure are likely candidates for such a therapy as they often experience significant comorbidity including cardiovascular diseases that require anticoagulation. Patients with renal failure on new anticoagulants have experienced excessive bleeding which can be related to a changed pharmacokinetic profile of the compounds. However, the coagulation system itself, even without any interference with coagulation modifying drugs, is already profoundly changed during renal failure. Coagulation disorders with either episodes of severe bleeding or thrombosis represent an important cause for the morbidity and mortality of such patients. The underlying reasons for these coagulation disorders involve the changed interaction of different components of the coagulation system such as the coagulation cascade, the platelets and the vessel wall in the metabolic conditions of renal failure. Recent work provides evidence that new factors such as microparticles (MPs) can influence the coagulation system in patients with renal insufficiency through their potent procoagulatory effects. Interestingly, MPs may also contain microRNAs thus inhibiting the function of platelets, resulting in bleeding episodes. This review comprises the findings on the complex pathophysiology of coagulation disorders including new factors such as MPs and microRNAs in patients with renal insufficiency.

Effect of ampicillin on the bleeding time of neonatal intensive care unit patients

OBJECTIVE

Studies in adults indicate that ampicillin, in a dose-dependent manner, impairs platelet function and moderately prolongs the bleeding time (generally by 60 to 90 s). Unlike aspirin, the inhibition induced by ampicillin involves both reversible and irreversible mechanisms and is not observed immediately after initial dosing (generally requiring approximately 24 h). Ampicillin is administered commonly to neonatal intensive care unit (NICU) patients, but its effect on bleeding time in this population has not been reported earlier.

STUDY DESIGN

We performed neonatal template bleeding times and platelet function analyzer (PFA)-100 tests on 15 NICU patients before and at various intervals after intravenous ampicillin dosing.

RESULT

Neonates were only studied if no beta-lactam antibiotics were administered to their mother during labor, and if they had ampicillin ordered by the clinician at a dose of 50 to 100 mg kg(-1) every 12 h. Subjects ranged from 33 to 41 weeks gestation and weighed 1760 to 3835 g. Bleeding times before the first ampicillin dose (n=15) averaged 134 s (95% confidence interval (CI), 120 to 148 s) and PFA-100 times averaged 123 s (95% CI, 96 to 149 s). After the first dose of ampicillin (n=5), bleeding times and PFA-100 times did not increase, but after the third (n=5) and fourth doses (n=4) bleeding times lengthened by an average of 60 s (95% CI, 37 to 83 s, P<0.001) and PFA-100 times lengthened by an average of 20 s (95% CI, -20 to 60 s, P=0.15).

CONCLUSION

Ampicillin administered intravenously to NICU patients prolongs the bleeding time, with a magnitude-of-effect and time-to-effect similar to that shown earlier in adults.

Drug-induced thrombocytopenia in critically ill patients

Thrombocytopenia occurs in 15% to 58% of intensive care unit patients. The incidence varies based upon patient population, timing and frequency of platelet monitoring, and definition of thrombocytopenia. Up to 25% of acutely ill patients develop drug-induced thrombocytopenia. When drug-induced thrombocytopenia is suspected, nondrug related causes must be evaluated and excluded. Establishing the diagnosis of drug-induced thrombocytopenia is challenging, as hundreds of medications have been implicated. Medications commonly associated with drug-induced thrombocytopenia include glycoprotein IIb/IIIa inhibitors, cinchona alkaloids, antibiotics, anticonvulsants, and heparin. Once the diagnosis is suspected, clinicians should identify the start date of medications to assess the timeline of development. The likelihood of each medication causing thrombocytopenia must be evaluated. The risk vs. benefit of discontinuing the suspected medication and availability of alternative medications must be assessed. The role of corticosteroids, immune globulin, and plasmapheresis is uncertain. Once the offending agent has been discontinued, the overall prognosis is excellent. In the case of suspected or confirmed heparin-induced thrombocytopenia, an alternative anticoagulant should be initiated. Drug-induced thrombocytopenia should be documented in the medical record and reported according to institutional and national standards. This review focuses on immune-mediated drug-induced thrombocytopenia from medications commonly utilized in the critically ill patient.

Ibuprofen lysine administration to neonates with a patent ductus arteriosus: effect on platelet plug formation assessed by in vivo and in vitro measurements

OBJECTIVE

Ibuprofen might have advantages over indomethacin, when used to effectuate closure of a neonate's patent ductus arteriosus (PDA). Several previous studies indicate that platelet plug formation is impaired after administration of indomethacin, but it is not clear whether a similar impairment occurs following ibuprofen dosing.

STUDY DESIGN

We performed template bleeding times and PFA-100 tests (platelet function analyzer) on 20 neonates who had a PDA, before and again at various preset intervals following ibuprofen dosing.

RESULT

Patients ranged from 23 to 40 weeks gestation and weighed 511 to 2566 g. Their first dose of ibuprofen was administered at 72 h (18 to 363 h) after birth (median, range). None of the subjects had clinical bleeding problems noted during the days they received ibuprofen dosing. The template bleeding times before dosing ranged from 135 to 450 s. Repeat tests were performed in groups of four, at 2 h, 4 to 6 h, 12 to 18 h, 24 h after the first dose, and at 2 h after the third dose of ibuprofen. No changes in bleeding times were detected. (P=0.299) A PFA-100 time was performed on all 20 patients before and again after the ibuprofen administration. However, 3 of the 40 tests were unsuccessful, because of microclots in the blood sample (n=1) or failure of the analyzer for an unspecified reason (n=2). Before the dosing the PFA-100 time ranged from 52 to 300 s. A paired t-test showed a slight but statistically significant lengthening in PFA-100 time after the ibuprofen administration (P=0.019). The correlation between the bleeding time and the PFA-100 was poor (R(2)=0.212, P=0.576).

CONCLUSION

On the basis of our present studies, we speculate that ibuprofen lysine administration to neonates with a PDA, when used according to the manufacturer's recommendations, has little adverse effect on platelet plug formation. This information might be a factor to consider when deciding whether to select indomethacin or ibuprofen for PDA closure.

Antibiotic adverse reactions and drug interactions

When contemplating antibiotic use, intensivists must consider possible beneficial and harmful drug interactions. After antibiotics are instituted, adverse reactions must be anticipated. Acute illness, comorbidities, and concurrent medications affect the presentation and management of antibiotic-related adverse events. Intensivists should use the fewest possible antibiotics, carefully choosing agents that maximize antimicrobial activity and minimize potential drug interactions and adverse reactions.

Template bleeding times of 240 neonates born at 24 to 41 weeks gestation

OBJECTIVE

The template bleeding time is a test used to assess the hemostatic effectiveness of platelet/endothelial interactions. A modified template bleeding time, described over 15 years ago by Andrew et al., has been used to test this aspect of hemostasis in term and preterm infants, but questions remain regarding the effect of gestational age and postnatal age on results. The effect of the platelet count (platelets per microliter blood) and the circulating platelet mass (nl platelets per microliter blood) on the bleeding time of neonatal intensive care unit (NICU) patients also require better definition.

STUDY DESIGN

We measured template bleeding times on 240 neonates at Ospedale A Perrino, in Brindisi, Italy; studying groups of n=60 at the following gestational ages; <28 weeks, 29 to 32 weeks, 33 to 37 weeks and > or =38 weeks. In each group of 60 neonates, 20 were studied on the first day after birth, 20 were studied on day 10 and 20 were studied on day 30. A multivariate analysis was performed to examine various associations with bleeding time.

RESULT

Bleeding times, on the first day of life, were shorter as gestational age increased. Those born <33 weeks gestation had bleeding times about twice that of those > or =38 weeks (P<0.001). Bleeding times tended to shorten between days 1 and 10. Little or no further shortening occurred between days 10 and 30, and by day 30 they were not statistically different between the various gestational age groups. No independent effect on bleeding time could be ascribed to gender, platelet count or circulating platelet mass, but independent effects were found for hematocrit (P<0.02) and gestational age (P<0.001).

CONCLUSION

On the first day of life, preterm neonates have a longer bleeding time than do term neonates. By day of life 10, the bleeding times at all gestational ages are shorter and are indistinguishable on the basis of gestational age at birth. Additionally, since platelet counts as low as 110 000 per microliter did not prolong the bleeding time, we see no benefit of administering a platelet transfusion to a stable, nonbleeding, NICU patient with mild thrombocytopenia (platelet count 100 000 to 150 000 per microliter).

Advances and controversies in neonatal ICU platelet transfusion practice

Some of the platelet transfusions currently given to NICU patients are unnecessary and convey no benefits. Although ordered with good intentions, unnecessary platelet transfusions carry known and unknown risks. Identifying and eliminating any unnecessary platelet transfusions in NICUs would be a step toward better care, lower costs, and more careful preservation of blood component resources. A renewed interest in platelet transfusion studies is needed, if essential data is to be gathered to improve NICU platelet transfusion practice. Retrospective studies can be of value: for instance, seeking associations between bleeding events and platelet counts can suggest the possibility of cause and effect relationships. Such studies might identify approximate platelet count levels that convey high hemorrhagic risk and might help focus future prospective trials. Prospective indirect studies also can be of value, for instance, measuring the template bleeding time and the PFA-100 closure time as a function of platelet count and perhaps as a function of circulating platelet mass, and would provide new information with relevance to platelet transfusion benefits. Such studies might give a better awareness of how low the platelet count can fall before platelet plug formation is impaired. It seems inescapable, however, that new, multicentered, randomized, prospective studies are needed, where NICU patients are assigned different platelet transfusion triggers and then carefully tracked for bleeding events and long-term neurodevelopmental outcomes. Only that type of study is likely to generate the evidence base needed for widespread implementation of improvements in NICU platelet transfusion practice.

Platelet dysfunction and end-stage renal disease

Patients with end-stage renal disease (ESRD) develop hemostatic disorders mainly in the form of bleeding diatheses. Hemorrhage can occur at cutaneous, mucosal, or serosal sites. Retroperitoneal or intracranial hemorrhages also occur. Platelet dysfunction is the main factor responsible for hemorrhagic tendencies in advanced kidney disease. Anemia, dialysis, the accumulation of medications due to poor clearance, and anticoagulation used during dialysis have some role in causing impaired hemostasis in ESRD patients. Platelet dysfunction occurs both as a result of intrinsic platelet abnormalities and impaired platelet-vessel wall interaction. The normal platelet response to vessel wall injury with platelet activation, recruitment, adhesion, and aggregation is defective in advanced renal failure. Dialysis may partially correct these defects, but cannot totally eliminate them. The hemodialysis process itself may in fact contribute to bleeding. Hemodialysis is also associated with thrombosis as a result of chronic platelet activation due to contact with artificial surfaces during dialysis. Desmopressin acetate and conjugated estrogen are treatment modalities that can be used for uremic bleeding. Achieving a hematocrit of 30% improves bleeding time in ESRD patients.

The use of piperacillin/tazobactam (in association with amikacin) in neonatal sepsis: efficacy and safety data

Piperacillin/tazobactam (P/T) has been used in NICU since 1999 as part of the empirical treatment for presumed sepsis. We studied the microbiological and clinical efficacy and safety of P/T use in newborns with sepsis, using a retrospective analysis of medical records of all newborns treated with P/T (in association with amikacin) during 1999-2003. P/T plus amikacin was used for 353 episodes of presumed sepsis occurring in 252 newborns: 105 episodes occurred in 100 newborns treated for 5-14 d while in 248 (70%) episodes the treatment was discontinued after 2-3 d. 123 pathogens were isolated from the blood cultures (40 in the 5-14 d group and 83 in those treated for 2-3 d only). There were 56 Gram-negative, 55 Gram-positive and 12 Candida spp. isolates. Klebsiella spp. (40%) and E. coli (30%) were the most commonly isolated Gram-negative pathogens; coagulase-negative Staphylococcus (CONS) represented 95% of the Gram-positive pathogens isolated. Pathogen eradication was achieved within 48-72 h of therapy in 93% Gram-negative organisms. There were no clinical, laboratory or cranial ultrasound adverse effects associated with P/T use. We conclude that P/T in association with amikacin is microbiologically and clinically efficacious and safe in the treatment of sepsis in newborns.

Piperacillin induced bone marrow suppression: a case report

BACKGROUND

Piperacillin (and piperacillin/tazobactam) is a commonly prescribed antibiotic and is generally considered safe. We report a case of piperacillin induced bone marrow suppression.

CASE PRESENTATION

A 19-year-old boy was being treated with piperacillin followed by piperacillin/tazobactam for infected pancreatic pseudocyst. After 21 days of treatment, he developed neutropenia and thrombocytopenia. These reversed promptly after stopping piperacillin/tazobactam. The time course of events suggested that piperacillin was the cause of bone marrow suppression in this patient.

CONCLUSION

Bone marrow suppression is a serious adverse effect of piperacillin, which should be kept in mind while treating patients with this drug.

Worldwide assessment of linezolid's clinical safety and tolerability: comparator-controlled phase III studies

Linezolid, an oxazolidinone antibiotic, has 100% oral bioavailability and favorable activities against gram-positive pathogens including multidrug-resistant staphylococci, enterococci, and pneumococci. Safety assessments were conducted for 2,046 linezolid-treated patients and 2,001 comparator drug-treated patients from seven controlled clinical trials comparing the activities of linezolid and comparator drugs against nosocomial and community-acquired pneumonia, skin and skin structure infections, and methicillin-resistant staphylococcal infections. Drug-related adverse events were primarily transient. The most frequent (> or = 2%) adverse events caused by linezolid and the comparator drugs were diarrhea (4.3 and 3.2%, respectively; P = 0.074), nausea (3.4 and 2.3%, respectively; P = 0.036), and headache (2.2 and 1.3%, respectively; P = 0.047). Treatment discontinuations due to drug-related events (2.4 and 1.9%, respectively), serious adverse events (11.4 and 10.6%, respectively), and deaths (4.8 and 4.9%, respectively) were similar. No clinically significant drug-related hematologic events were reported, and laboratory safety data were comparable. In the first 6 months of postmarketing surveillance, hematologic abnormalities were reported in 0.1% of linezolid-treated patients, but no irreversible blood dyscrasias were documented. The risk for transient, reversible hematologic effects from treatment with linezolid should be considered together with the clinical benefits associated with its use.

Hematologic effects of linezolid: summary of clinical experience

Linezolid has been associated with reversible myelosuppression. Clinical trial data were evaluated for anemia, thrombocytopenia, and neutropenia. Thrombocytopenia and a slight increased risk for anemia were evident at > or =2 weeks of linezolid treatment. Hematologic abnormalities were consistent with mild, reversible, duration-dependent myelosuppression. Appropriate monitoring is warranted with linezolid use.

Platelet aggregation during abdominal surgery in an experimental pig model: the effects of presurgical antibiotic protocols and volume replacement with hydroxyethyl starch

The effect of presurgical antibiotic protocols in combination with hemodilution on platelet aggregation was studied. Thirty pigs were randomly assigned to three groups. Group 1 received amoxicillin/clavulanic acid, group 2 metronidazole+cefuroxime, and group 3, as a control, sodium chloride. They underwent laparotomy, massive blood loss, and volume replacement with hydroxyethyl starch 200, followed by an anaphylactoid reaction. Platelet aggregation was measured by the turbidometric method. Neither antibiotic protocols had any effect on platelet aggregation as compared with the control group. In all three groups, aggregation to ADP and collagen was significantly reduced after volume replacement with hydroxyethyl starch. In contrast, the sensitivity to the aggregating effects of collagen was increased as assessed by a higher frequency of responses to low concentrations of collagen and a shortened latency of the aggregation response after collagen addition. Further in vitro studies revealed that dilution of plasma with hydroxyethyl starch specifically induced the changes seen after in vivo volume replacement. The results suggest that the plasma substitute hydroxyethyl starch 200 increases the sensitivity to low doses of collagen, an effect never described before and considered of clinical relevance.

Principles of antibiotic prescribing in the elderly

Clinicians providing care to elderly patients must appreciate the subtle clinical manifestations that herald the onset of life-threatening infectious disease. Aged patients with an infection may have neither fever nor leucocytosis, making diagnosis challenging. Often, the early features of infectious disease are nonspecific and may resemble inflammatory or neoplastic processes, or there may be insufficient time to await definitive laboratory confirmation, and empirical antimicrobial treatment must be initiated. Aging involves inevitable deleterious alterations in biological processes and, in many elderly patients, this is most strongly characterised by diminished renal functional capacity. This has a major influence on antimicrobial prescribing in the elderly, because therapeutic efficacy must be achieved while minimising the risk of drug-related toxicity. Before prescribing an antibiotic to an aged patient with an infection, the clinician must be cognisant of the patient's drug allergy history and the other drugs that the patient is taking. Ignorance of potential drug-drug interactions can result in ineffective treatment or enhanced toxicity. The therapy of elderly patients with infections is being expanded. To reduce costs and enhance the efficiency of care, systems have been developed to provide antimicrobial care in the home and in long term care facilities. Home healthcare has burgeoned, and drugs that are well tolerated, have a broad spectrum of activity and are simple to administer (e.g. ceftriaxone and fluoroquinolones) appear to be eminently suitable for this therapeutic role. Physicians must also be informed of the factors responsible for the emergence of resistant bacteria that are contributing to infections in institutional and community settings. Clinicians should strive to curb inappropriate antibiotic use to stem the tide of infections that are caused by multidrug-resistant bacteria.

Antibiotic selection in obstetric patients

Penicillin and ampicillin are valuable antibiotics in obstetrics because of their excellent activity against group A and group B streptococci. In addition, ampicillin is the treatment of choice for enterococcal infections, particularly urinary tract infections. Limited spectrum cephalosporins are of primary value as prophylactic agents. Ceftriaxone, an intermediate spectrum agent, is an excellent drug for treatment of infections caused by N. gonorrhoeae. Extended spectrum cephalosporins, penicillins, and carbapenems provide sufficient coverage against pathogenic organisms to be used as single agents for treatment of polymicrobial infections such as chorioamnionitis and puerperal endometritis. Alternatively, combination regimens such as clindamycin or metronidazole plus an aminoglycoside or aztreonam are also highly effective in this clinical situation. Erythromycin and azithromycin have value primarily for treatment of endocervical chlamydial infections and mycoplasma pneumonia in obstetric patients and for intrapartum prophylaxis against group B streptococcal infection in patients who are allergic to beta-lactam antibiotics.

Coagulation disorders in cancer

Coagulation disorders are common in cancer patients. This article reviews the coagulation laboratory findings in these patients and the thromboembolic and hemorrhagic manifestations of malignancy. Among the many topics addressed are Trousseau's syndrome, disseminated intravascular coagulation, and acquired von Willebrand disease. Pathogenesis of the coagulation disorders and recommendations for treatment of various syndromes are discussed.

Antipseudomonal penicillins

Antipseudomonal penicillins retain most of the antibacterial activity of penicillin and aminopenicillins. This group of penicillins has added activities against many gram-negative rods, including P. aeruginosa. Similar to the earlier penicillins, this group continues to be susceptible to hydrolysis by many beta-lactamases and are, therefore, not consistently active against Staphylococcus, some gram-negative rods, and certain beta-lactamase-producing gram-negative anaerobes. The ureidopenicillins, especially piperacillin, appear to have better activity against Enterococcus, Klebsiella, and P. aeruginosa than ticarcillin. The advantages over the newer cephalosporins are (1) better activity against Enterococcus, (2) more consistent activity against Clostridium, and (3) more consistent synergy with aminoglycosides. The ureidopenicillins have certain advantages over carboxypenicillins, including lower sodium load, less frequent hypokalemia, reduced platelet dysfunction, minimal dosage adjustment in patients with renal failure, and a wider spectrum of antibacterial activity, especially against Enterococcus, Pseudomonas, and Klebsiella. The utility of the antipseudomonal penicillins by themselves is limited as agents for monotherapy when the infecting organism is not known. In addition, monotherapy is not recommended in certain infections to avoid the development of resistance. When combined with a beta-lactamase inhibitor or with an aminoglycoside, however, some of the weaknesses can be overcome.

Hemostasis in renal disease: pathophysiology and management

The hemostatic abnormalities commonly encountered in patients with renal disease can significantly threaten the well-being of the patient and pose difficult management issues for the clinician. In this review, we explore the pathophysiology underlying the bleeding diathesis and hypercoagulability that can occur. Current therapeutic interventions are also discussed.

In vitro and ex vivo effects of aspirin in patients on a low-dose aspirin therapy

In 19 patients on a low-dose aspirin therapy with 100 mg/d, an insufficient effect of aspirin was observed in five patients (aggregations induced by arachidonic acid and collagen, thromboxane B2-formation in serum and after collagen). Aspirin added in vitro increased the inhibition to a degree comparable to that seen in the other 14 patients, i.e. the insufficient effect could be due to a lack of compliance or to a reduced availability of the drug. In another 20 patients there was a good inhibitory effect of aspirin; additional aspirin did not increase the inhibition of arachidonic acid-induced aggregation and serum-thromboxane B2, but slightly increased collagen-induced aggregation and thromboxane B2 formation. The effect was the same, whether the aspirin was given in vivo or added in vitro.

Isolated severe thrombocytopenia and bleeding caused by piperacillin

Bleeding and severe thrombocytopenia developed in a 71-year-old man who had been receiving piperacillin 5 g intravenously every 8 h for 9 days for the treatment of Pseudomonas aeruginosa septicemia. After piperacillin was discontinued, the platelet counts became normal. Rechallenge was made with 2 g of piperacillin intravenously resulting in thrombocytopenia within 6 h of piperacillin administration. The platelet count normalized after 3 days when no further piperacillin was given.

Antimicrobial therapy for pediatric patients

New antimicrobial agents are being introduced for clinical use at an increasingly rapid rate. This has required physicians continually to review relevant data and determine unique properties that might guide selection among any new antibiotics as well as older ones. Efficacy, potential toxicity, and comparative cost (in that order) generally guide selection. The present comprehensive review examines currently available antibiotics along with some under investigation, emphasizing these three basic areas of consideration.