A review of the toxicity in fish exposed to antibiotics.

Antibiotics are widely used in the treatment of human and veterinary diseases and are being used worldwide in the agriculture industry to promote livestock growth. However, a variety of antibiotics that are found in aquatic environments are toxic to aquatic organisms. Antibiotics are not completely removed by wastewater treatment plants and are therefore released into aquatic environments, which raises concern about the destruction of the ecosystem owing to their non-target effects. Since antibiotics are designed to be persistent and work steadily in the body, their chronic toxicity effects have been studied in aquatic microorganisms. However, research on the toxicity of antibiotics in fish at the top of the aquatic food chain is relatively poor. This paper summarizes the current understanding of the reported toxicity studies with antibiotics in fish, including zebrafish, to date. Four antibiotic types; quinolones, sulfonamides, tetracyclines, and macrolides, which are thought to be genetically toxic to fish have been reported to bioaccumulate in fish tissues, as well as in aquatic environments such as rivers and surface water. The adverse effects of these antibiotics are known to cause damage to developmental, cardiovascular, and metabolic systems, as well as in altering anti-oxidant and immune responses, in fish. Therefore, there are serious concerns about the toxicity of antibiotics in fish and further research and strategies are needed to prevent them in different regions of the world.

Semi-mechanistic PK/PD modelling of combined polymyxin B and minocycline against a polymyxin-resistant strain of Acinetobacter baumannii.

OBJECTIVES: To expand on previous reports of synergy between polymyxin B (PMB) and minocycline (MIN) against Acinetobacter baumannii; and to gain insight into the qualitative and quantitative determinants of their synergy. METHODS: A semi-mechanistic pharmacokinetic/pharmacodynamic (PK/PD) model was developed on the basis of data from in vitro time-kill experiments with determination of resistant bacterial count to describe the effects of PMB and MIN alone and in combination. The model was enriched by complementary experiments providing information on the characteristics of the resistant subpopulation. RESULTS: The model successfully described the data and made possible quantification of the strength of interaction between the two drugs and formulation of hypotheses about the mechanisms of the observed interaction. The effect of the combination was driven by MIN, with PMB acting as an helper drug; simulations at clinically achievable concentrations showed that 1.5 mg/L MIN +0.2 mg/L PMB is expected to produce sustained killing over 30 hours, while 0.3 mg/L MIN +1 mg/L PMB is met by bacterial regrowth. Interaction equations showed that maximal synergy is reached for PMB concentrations ≥0.1 mg/L and MIN concentrations ≥1 mg/L. CONCLUSIONS: Semi-mechanistic PK/PD modelling was used to investigate the quantitative determinants of synergy between PMB and MIN on a PMB-resistant A. baumannii strain. The developed model, improving on usual study techniques, showed asymmetry in the drug interaction, as PMB acted mostly as a helper to MIN, and provided simulations as a tool for future studies.

Occupational inhalation poisoning with the veterinary antibiotic tiamulin.

Introduction: Tiamulin is a semisynthetic pleuromutilin diterpene veterinary antibiotic, widely used in farms. We present a case of prolonged QT-interval and ventricular tachyarrhythmia after tiamulin inhalation.Case presentation: A 43-year-old veterinarian without previous medical history was dividing granulated powder of antibiotic gravimetrically without wearing personal protective equipment. Half an hour after exposure, nausea occurred; four hours later he started to vomit and soon after that he experienced syncope. He was unconscious three minutes; afterwards he became somnolent, dizzy and nauseated with sweating and salivation. On admission to hospital five hours after exposure, he was conscious and had heart rate 70 beats/min and blood pressure 140/80 mmHg. Initial laboratory results were normal. Electrocardiography showed a prolonged QTc-interval of 730 ms with numerous polymorphic ventricular extrasystoles and episodes of non-sustained polymorphic ventricular tachycardia that resolved after treatment with lidocaine and magnesium. Subsequent electrocardiography revealed gradual shortening of QTc-interval with QTc-interval normalization (430 ms) between 24 and 32 hours after tiamulin exposure. Laboratory tests, morphologic heart diagnostics and genetic testing excluded other potential causes of QTc-interval prolongation. Subsequent toxicology analysis by LC-MS/MS confirmed tiamulin in his serum samples on admittance (500 ng/mL).Conclusion: Tiamulin inhalation can be associated with prolonged QT-interval and ventricular tachyarrhythmia. QT-interval prolongation could be expected in overdoses of emerging human pleuromutilins.

Synergistic Efficacy of ß-Lactam Combinations against Mycobacterium abscessus Pulmonary Infection in Mice.

Mycobacterium abscessus is an emerging pathogen capable of causing invasive pulmonary infections in patients with chronic lung diseases. These infections are difficult to treat, necessitating prolonged multidrug therapy, which is further complicated by extensive intrinsic and acquired resistance exhibited by clinical M. abscessus isolates. Therefore, development of novel treatment regimens effective against drug-resistant strains is crucial. Prior studies have demonstrated synergistic efficacy of several ß-lactams against M. abscessusin vitro; however, these combinations have never been tested in an animal model of M. abscessus pulmonary disease. We utilized a recently developed murine system of sustained M. abscessus lung infection delivered via an aerosol route to test the bactericidal efficacy of four novel dual ß-lactam combinations and one ß-lactam/ß-lactamase inhibitor combination. All five of the novel combinations exhibited synergy and resulted in at least 6-log10 reductions in bacterial burden in the lungs of mice at 4 weeks compared to untreated controls (P = 0.038).

[Vancomycin poisoning successfully treated with intermittent hemodialysis: A case report]. / Un cas d'intoxication à la vancomycine traité avec succès par hémodialyse intermittente.

We report a case of a 43 years old man who was intoxicated by a 25g vancomycin overload. An anuric acute renal failure rapidly occured. The vancomycinemia was measured as high as 360mg/L (normal range: 15-35mg/L). We started an intermittent hemodialysis program to clear out the vancomycin. The vancomycinemia decreased below the treshold of our laboratory after the eighth session. Three supplementary sessions were needed because of a persistant oliguria. The kidney function slowly improved and was back to normal (seric creatinin: 80micromol/L) 3 weeks after the patient had gone home. To our knowledge, it is the first success of this technic concerning vancomycin poisoning in adults with anuric kidney failure.

Survival After Severe Rhabdomyolysis Following Monensin Ingestion.

INTRODUCTION: Monensin is a veterinary antibiotic with a narrow therapeutic window that has led to lethal intoxication in many animal species. Only two prior cases of human toxicity have been reported, both fatal. We present the first case of survival from severe toxicity following monensin ingestion. CASE: A 58-year-old man presented with 8 days of vomiting and abdominal pain. Due to delusions of central nervous system toxoplasmosis, he ingested 300 mg of monensin. His laboratory studies revealed severe rhabdomyolysis without renal dysfunction. Total creatine kinase (CK) peaked above 100,000 U/L. His CK decreased to 5192 U/L after 15 days of aggressive hydration and sodium bicarbonate therapy. His ejection fraction on echocardiogram decreased from 69 to 56%. DISCUSSION: Reports on acute clinical effects after human exposure to monensin are limited. Ingestion is known to cause skeletal and cardiac muscle rhabdomyolysis and necrosis. Animal studies demonstrate that monensin's toxicity is due to increases in intracellular sodium concentrations and Ca2+ release. To date, no effective antidotal treatment has been described. CONCLUSIONS: Monensin is a veterinary medication not approved for human use by the US Food and Drug Administration. Though poorly studied in humans, this case demonstrates the severe harm that may occur following ingestion.

Use, fate and ecological risks of antibiotics applied in tilapia cage farming in Thailand.

The use, environmental fate and ecological risks of antibiotics applied in tilapia cage farming were investigated in the Tha Chin and Mun rivers in Thailand. Information on antibiotic use was collected through interviewing 29 farmers, and the concentrations of the most commonly used antibiotics, oxytetracycline (OTC) and enrofloxacin (ENR), were monitored in river water and sediment samples. Moreover, we assessed the toxicity of OTC and ENR on tropical freshwater invertebrates and performed a risk assessment for aquatic ecosystems. All interviewed tilapia farmers reported to routinely use antibiotics. Peak water concentrations for OTC and ENR were 49 and 1.6 µg/L, respectively. Antibiotics were most frequently detected in sediments with concentrations up to 6908 µg/kg d.w. for OTC, and 2339 µg/kg d.w. for ENR. The results of this study indicate insignificant short-term risks for primary producers and invertebrates, but suggest that the studied aquaculture farms constitute an important source of antibiotic pollution.

[Early macular edema after phacoemulsification and suspected overdose of cefuroxime: report of six cases]. / Œdème maculaire après phacoémulsification et suspicion de surdosage en céfuroxime : à propos de 6 cas.

Antibiotic prophylaxis by intracameral cefuroxime injection, 1mg/0.1 mL after cataract surgery is increasing in popularity. Several cases of early postoperative macular edema have recently been reported after cefuroxime injection, most of them due to accidental cefuroxime overdose. We report six additional cases of macular involvement after cataract surgery, with intracameral cefuroxime injection imputed to cause retinal toxicity. Formal proof of cefuroxime overdose has never been possible, due to rapid wash-out in a few hours and the diagnosis of the macular edema the day after surgery or within a few days. Thus, this strong suspicion is based on clinical, pharmacokinetic, tomographic and retinographic criteria. In our series of six cases, the first four patients involved the same surgeon in the same hospital, and two of them on the same day. For the sixth case, the diagnosis was made retrospectively and based on history and medium-term tomographic characteristics. All the patients underwent optical coherence tomography (OCT) relatively early. As early as day one after surgery, there is macular edema predominantly in the outer retinal layers associated with serous retinal detachment, similar to the cases described in the literature. In the late stage, three patients had functional impairment related to photoreceptor damage on OCT. Three cases are described with additional retinal imaging (angiography, autofluorescence) to better characterize this macular toxicity associated with cefuroxime.

Cefepime neurotoxicity in the intensive care unit: a cause of severe, underappreciated encephalopathy.

INTRODUCTION: Cefepime, a broad spectrum antibiotic, is commonly prescribed in intensive care units (ICU) and may be an overlooked cause of neurologic symptoms such as encephalopathy, myoclonus, seizures, and coma. We aimed to characterize cefepime neurotoxicity in the ICU. METHODS: We performed a retrospective study of adult ICU patients treated with intravenous cefepime for at least 3 days between January 1, 2009 and December 31, 2011. The primary outcome was the development of cefepime neurotoxicity, with the likelihood of causality ascribed via a modified Delphi method. RESULTS: This study included 100 patients. The mean age was 65.8 years (± 12.7 years). The median daily average dose of cefepime was 2.5 (IQR 2.0 to 3.5) grams. The median treatment duration was 6 (IQR 4 to 10) days. Renal failure in any form was present in 84 patients. Chronic kidney disease affected 40 patients, and 77 had acute kidney injury. Cefepime neurotoxicity occurred in 15 patients. Of these, seven were considered definite cases, three probable, and five possible. Neurotoxic symptoms included impaired consciousness (n = 13), myoclonus (n = 11), disorientation (n = 6), and nonconvulsive status epilepticus (n = 1). The dose of cefepime was appropriately adjusted for renal clearance in 64 patients (75.3%) without cefepime neurotoxicity and four patients (28.6%) with neurotoxicity (P = 0.001). Chronic kidney disease was present in 30 patients (35.3%) without neurotoxicity and in 10 (66.7%) of those with neurotoxicity (P = 0.04). CONCLUSIONS: Critically ill patients with chronic kidney disease are particularly susceptible to cefepime neurotoxicity. Myoclonus and impaired consciousness are the predominant clinical manifestations. Neurotoxic symptoms occur more often when the cefepime dose is not adjusted for renal function, but can still occur despite those modifications.

Fluoroquinolone (FQ) contamination does not correlate with occurrence of FQ-resistant bacteria in aquatic environments of Vietnam and Thailand.

Fluoroquinolone antibiotics (FQs) have been used worldwide for chemotherapy, animal husbandry, and aquaculture, and the occurrence of FQ-resistant (FQs(r)) bacteria in natural environments has been reported. Plasmid-mediated transferable quinolone resistance (PMQR) genes are suspected to originate from the chromosomes of water-dwelling bacteria. However, the occurrence of and the potential reservoir of FQs(r) bacteria and PMQR genes in aquatic environments have not been elucidated. In this study, we detected FQs(r) bacteria and PMQR genes in aquatic environments in Thailand and Vietnam, and measured FQ contamination. Levels of contamination were greater Thailand (avg. 5130, max 46100 ng L(-1)) than in Vietnam (avg. 235, max 1130 ng L(-1)); however, the occurrence of FQs(r) bacteria was higher in Vietnam (~15%) than in Thailand (~7.0%), suggesting that contamination by FQs is not directly linked to the development of FQs(r) bacteria. Diverse taxonomic groups of FQs(r)-bacteria were identified, and one of the PMQR genes, qnrB, was detected from bacteria of environmental origin, not enteric bacteria. This suggests that the environmental bacteria are a potential reservoir of antibiotic resistance determinants even at un-contaminated sites.

[Gentamicin intoxication in a preterm infant]. / Gentamicin Intoxikation bei einem Frühgeborenen.

Gentamicin is an aminoglycoside that is widely used in neonatology in spite of its known nephrotoxicity and ototoxicity. Because there are only few cases reported in the literature experience with gentamicin overdosage is limited. We report the case of a preterm (gestational age 32+2 weeks) infant with an accidental administration of a ten-fold dose of gentamicin. The baby was treated with a slight increase of fluid intake and monitoring of renal function and gentamicin levels, respectively. A rapid decrease of the gentamicin level (peak level 44.5 mg/L, extrapolated peak level 65 mg/L) was observed. Nephrotoxicity or ototoxicity did not occur. Because of the small number of described cases, a general recommendation for the management of gentamicin intoxication is not possible. The intensity of treatment depends on renal function and gentamicin level. Only isolated patients will need dialysis or exchange transfusion. The case also demonstrates the need for the continuous discussion about hospital-associated damage and error management systems.

American association of poison control centers database characterization of human tilmicosin exposures, 2001-2005.

BACKGROUND: Tilmicosin is a veterinary antibiotic with significant human toxicity at doses commonly used in animals, but the parenteral dose-response relationship has not been well characterized. METHODS: Human exposures to tilmicosin in the database of the American Association of Poison Control Centers (AAPCC) from 2001 to 2005 were analyzed for demographic associations, exposure dose, clinical effects and outcomes. RESULTS: Over the 5-year period, there were 1,291 single-substance human exposures to tilmicosin. The mean age was 39.1 years, and 80% were male. By route there were 768 (54%) parenteral exposures. Patients with parenteral exposures had a significantly increased likelihood of being seen at a healthcare facility, admission, and admission to an ICU. With nonparenteral exposure, most had no clinical effects or minor effects, and there were no major effects or deaths. With parenteral exposure, moderate effects occurred in 46 (6%), major effects in 2 (0.3%) and there were 4 (0.5%) deaths, two of which were suicides. A dose-response relationship could be demonstrated. Clinical effect durations of up to a week occurred at even the lowest dose range. CONCLUSIONS: Over 250 cases of human tilmicosin exposure are reported to poison centers per year and over 150 of those are parenteral. Most exposures produce no or minor effects, but fatalities have occurred with parenteral exposure. The case fatality rate in parenteral exposures is 10 times the case fatality rate for all human exposures in the AAPCC database. Significant adverse and prolonged effects are reported at parenteral doses > 0.5 mL, suggesting that all parenteral exposures should be referred for healthcare facility evaluation.

Effect of eucalyptus essential oil on respiratory bacteria and viruses.

The activity of Eucalyptus globulus essential oil was determined for 120 isolates of Streptococcus pyogenes, 20 isolates of S. pneumoniae, 40 isolates of S. agalactiae, 20 isolates of Staphylococcus aureus, 40 isolates of Haemophilus influenzae, 30 isolates of H. parainfluenzae, 10 isolates of Klebsiella pneumoniae, 10 isolates of Stenotrophomonas maltophilia and two viruses, a strain of adenovirus and a strain of mumps virus, all obtained from clinical specimens of patients with respiratory tract infections. The cytotoxicity was evaluated on VERO cells by the MTT test. The antibacterial activity was evaluated by the Kirby Bauer paper method, minimum inhibitory concentration, and minimum bactericidal concentration. H. influenzae, parainfluenzae, and S. maltophilia were the most susceptible, followed by S. pneumoniae. The antiviral activity, assessed by means of virus yield experiments titered by the end-point dilution method for adenovirus, and by plaque reduction assay for mumps virus, disclosed only a mild activity on mumps virus.

Surveillance of prescription drug-related mortality using death certificate data.

BACKGROUND: The prescription drugs or drug classes that are most frequently associated with death in the US might be identifiable from death certificate data. OBJECTIVE: To identify the drugs/drug classes associated with the greatest numbers of deaths in the US that might be considered as possible targets for prevention. STUDY DESIGN: US vital statistics data were accessed in order to identify International Classification of Diseases (10th Revision) [ICD-10] codes indicating that prescription drugs had caused or contributed to death and diseases with significant drug-related mortality. MAIN OUTCOME MEASURE: ICD-10 codes for primarily prescription drugs that were listed as the underlying cause or as 'total mentions' on death certificates and were implicated in >or=1000 deaths in any one year were selected. The annual number of deaths by ICD-10 code was obtained from the Division of Vital Statistics, National Center for Health Statistics. Codes for diseases with significant drug-related aetiologies and involvement in >or=1000 deaths in any one year were also identified and analysed separately. RESULTS: For the selected ICD-10 codes, a total of 25 031 deaths were listed as having a prescription drug as the underlying cause in 2003, compared with 16 135 in 1999, a 55% increase. Total mentions of these codes increased from 46 523 in 1999 to 72 080 in 2003, also a 55% increase. Most codes involved 'poisonings' (overdose or the wrong substance given or taken in error that is accidental, intentional or with undetermined intent). Drugs associated with poisoning deaths had central nervous system effects. Among the codes associated with specified drug classes, poisonings and accidental poisonings involving narcotics, hallucinogens, psychoactive substances and opioids (other than opium and heroin) were associated with the largest numbers of deaths. Drug-related codes associated with the largest percentage increases in deaths between 1999 and 2003 included poisoning due to methadone (275%); poisoning by other and unspecified antidepressants (primarily selective serotonin reuptake inhibitors) [130%]; and poisoning by psychostimulants with potential for abuse (amfetamines and drugs for attention deficit hyperactivity disorder) [117%]. Anticoagulants were associated with the largest numbers of deaths with codes involving "adverse effects in therapeutic use". Among diseases with significant drug-related aetiologies, Clostridium difficile enterocolitis (associated primarily with antibacterials) had the largest percentage increase in total mentions, with a 203% rise between 1999 and 2003. CONCLUSIONS: Deaths due to overdoses are the most prominent cause of drug-related mortality in death certificate data. Certain drugs and drug classes, especially the opioids (e.g. narcotics, methadone), psychoactive drugs (e.g. antidepressants, amfetamines), anticoagulants and antibacterials (which cause or contribute to C. difficile enterocolitis) are associated with large and increasing numbers of deaths and preventive strategies should be considered.

Analysis of reports of human exposure to Micotil 300 (tilmicosin injection).

OBJECTIVE: To identify clinical signs associated with and outcome of human exposure to Micotil 300 (tilmicosin injection). DESIGN: Retrospective case series. STUDY POPULATION: Reports of 3,168 human exposures to Micotil 300. PROCEDURES: Reports of human exposure to Micotil 300 submitted to the Elanco Animal Health Pharmacovigilance Unit between March 1992 and March 2005 were reviewed. RESULTS: At least 1 clinical sign was described in 1,404 (44%) reports, whereas the remaining 1,764 (56%) exposures were presumably asymptomatic. Eighty percent of exposures involved males; mean age was 38 years. Sixty-one percent of exposures were a result of accidental injection, with injection site pain, bleeding, swelling, or inflammation being the most common signs, followed by nausea, tachycardia, dizziness, anxiety, an abnormal taste, headache, lightheadedness, limb pain, paresthesia, chest pain, and soreness. Only 156 (5%) reports involved serious adverse effects (ie, tachycardia, bradycardia, hypertension, hypotension, heart disorder, chest pain, tachypnea, or death). There were reports of 13 deaths following tilmicosin exposure, but only 2 of those deaths were related to accidental exposure. Time to onset of clinical signs was < or = 60 minutes in 63 of the 156 (40%) reports involving serious adverse effects. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the overall risk of accidental human exposure to tilmicosin resulting in serious adverse effects is low (approx 2 people for every 1 million doses administered). Nevertheless, safe handling and proper use should be emphasized.