Nosocomial infections and antimicrobial resistance in critical care medicine

Objective: To review the human and companion animal veterinary literature on nosocomial infections and antimicrobial drug resistance as they pertain to the critically ill patient. Data sources: Data from human and veterinary sources were reviewed using PubMed and CAB. Human data synthesis: There is a large amount of published data on nosocomially‐acquired bloodstream infections, pneumonia, urinary tract infections and surgical site infections, and strategies to minimize the frequency of these infections, in human medicine. Nosocomial infections caused by multi‐drug‐resistant (MDR) pathogens are a leading cause of increased patient morbidity and mortality, medical treatment costs, and prolonged hospital stay. Epidemiology and risk factor analyses have shown that the major risk factor for the development of antimicrobial resistance in critically ill human patients is heavy antibiotic usage. Veterinary data synthesis: There is a paucity of information on the development of antimicrobial drug resistance and nosocomially‐acquired infections in critically ill small animal veterinary patients. Mechanisms of antimicrobial drug resistance are universal, although the selection effects created by antibiotic usage may be less significant in veterinary patients. Future studies on the development of antimicrobial drug resistance in critically ill animals may benefit from research that has been conducted in humans. Conclusions: Antimicrobial use in critically ill patients selects for antimicrobial drug resistance and MDR nosocomial pathogens. The choice of antimicrobials should be prudent and based on regular surveillance studies and accurate microbiological diagnostics. Antimicrobial drug resistance is becoming an increasing problem in veterinary medicine, particularly in the critical care setting, and institution‐specific strategies should be developed to prevent the emergence of MDR infections. The collation of data from tertiary‐care veterinary hospitals may identify trends in antimicrobial drug resistance patterns in nosocomial pathogens and aid in formulating guidelines for antimicrobial use.     

Applying the One Health Concept to Mycobacterial Research – Overcoming Parochialism

Mycobacterial infections remain a public health problem. Historically important, globally ubiquitous and with a wide host range, we are still struggling to control mycobacterial infections in humans and animals. While previous reviews have focused on individual mycobacterial infections in either humans or animals, a comprehensive review of the zoonotic aspect of mycobacteria in the context of the One Health initiative is lacking. With the purpose of providing a concise and comprehensive resource, we have collated literature to address the zoonotic potential of different mycobacterial species and elaborate on the necessity for an inter‐sectorial approach to attain a new vision to combat mycobacterial infections.     

BRS virus, PI3 virus and BHV1 infections of young stock on self-contained dairy farms: epidemiological and clinical findings

The role of bovine respiratory syncytial virus, parainfluenza type 3 virus and bovine herpesvirus 1 as disease agents in 28 groups of young cattle on 19 dairy farms which raised their own replacements was investigated. Bovine respiratory syncytial virus infections occurred in 27, parainfluenza type 3 virus infections in all and bovine herpesvirus 1 infections in three of the 28 groups. Some infections were accompanied by clinical signs while others were entirely subclinical. Clinical respiratory disease was observed on 25 occasions in 20 of the groups. Respiratory disease was associated with a bovine respiratory syncytial virus infection on 15 occasions with parainfluenza type 3 virus infection in four cases and with bovine herpesvirus 1 infection in two cases. In four cases there was no association between the respiratory disease and any of the four virus infections. Bovine respiratory syncytial virus infections caused more serious respiratory problems than parainfluenza type 3 virus infections.     

The cox regression model applied to risk factor analysis of infections in the breeding and multiplying herds in the Danish SPF system

The Cox regression model is discussed with emphasis on model examination and selection. The model is applied in a multivariate risk factor analysis of Mycoplasma hyopneumoniae (MH) infections in the breeding and multiplying herds in the Danish specific pathogen-free (SPF) pig production system. The analysis showed that the pattern of infections was in agreement with the theory that both airborne transmission and spread through trade in subclinically infected animals are major causes of MH infections.     

Borrelia burgdorferi infections with special reference to horses. A review

Summary This review discusses the literature on B. burgdorferi infections in view of the rising incidence of this infection in general and the increasing concerns of horse owners and equine practitioners. Lyme disease, the clinical expression of Borrelia infections in man is an important health problem. The geographic distribution of B. burgdorferi infections in equidae should resemble that of human cases because the vector tick involved, Ixodes ricinus, feeds on both species and, indeed, the infection has been established many times in horses. However, a definite diagnosis of the disease "Lyme borreliosis" in human beings as well as in horses and other animals is often difficult to accomplish. Although a broad spectrum of clinical signs has been attributed to B. burgdorferi infections in horses, indisputable cases of equine Lyme borreliosis are extremely rare so far, if they exist at all.     

Borrelia burgdorferi infections with special reference to horses. A review

This review discusses the literature on B. burgdorferi infections in view of the rising incidence of this infection in general and the increasing concerns of horse owners and equine practitioners. Lyme disease, the clinical expression of Borrelia infections in man is an important health problem. The geographic distribution of B. burgdorferi infections in equidae should resemble that of human cases because the vector tick involved, Ixodes ricinus, feeds on both species and, indeed, the infection has been established many times in horses. However, a definite diagnosis of the disease "Lyme borreliosis" in human beings as well as in horses and other animals is often difficult to accomplish. Although a broad spectrum of clinical signs has been attributed to B. burgdorferi infections in horses, indisputable cases of equine Lyme borreliosis are extremely rare so far, if they exist at all.     

Methicillin-resistant Staphylococcus aureus: an emerging pathogen in small animals

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial pathogen in humans and is increasingly implicated in community-associated infections in people. In household pets, MRSA infections are uncommon but are on the rise, possibly because of the increased prevalence of human MRSA in the community. Clinical MRSA infections in some animals can be life threatening and difficult to treat; however, other animals may develop mild disease or only become colonized. Veterinarians should be aware of the concerns regarding MRSA and should develop an understanding of appropriate disease surveillance, diagnostic testing, and infection control in order to lessen the impact of MRSA on small animals.     

Multilocus-sequence typing analysis reveals similar populations of Streptococcus uberis are responsible for bovine intramammary infections of short and long duration

Multilocus-sequence typing (MLST) was used to analyse Streptococcus uberis isolates from a single herd associated with long duration (50-260 days) and rapidly cleared (less than 1 month) bovine intramammary infections to determine whether the bacterial type had any impact on the duration of infection. Most chronic infections (24 of 33) were due to continuous infection of the mammary quarter with the same sequence type, and infections were found to persist for many months. The remaining quarters were re-infected with a different sequence type within a single lactation. No particular sequence type or clonal complex (lineage) was associated with persisting infections, indicating that the outcome of intramammary infections with S. uberis is more likely to be dependent on host factors than on inter-strain differences. Analysis of these strains alongside others obtained from the same herd at a later date revealed the shift in the predominant genotypes with time.     

鸽I型副粘病毒病的研究进展

本文就鸽Ⅰ型副粘病毒病的国内外发生历史、流行特点、病原特性、临床症状、病理变化以及免疫防治等方面的研究进展进行了综合整理，以期对该病的深入研究和防制工作起推动作用。     

Modelling the dynamics of intramammary E. coli infections in dairy cows: understanding mechanisms that distinguish transient from persistent infections

The majority of intramammary infections with Escherichia coli in dairy cows result in transient infections with duration of about 10 days or less, although more persistent infections (2 months or longer) have been identified. We apply a mathematical model to explore the role of an intracellular mammary epithelial cell reservoir in the dynamics of infection. We included biological knowledge of the bovine immune response and known characteristics of the bacterial population in both transient and persistent infections. The results indicate that varying the survival duration of the intracellular reservoir reproduces the data for both transient and persistent infections. Survival in an intracellular reservoir is the most likely mechanism that ensures persistence of E. coli infections in mammary glands. Knowledge of the pathogenesis of persistent infections is essential to develop preventive and treatment programmes for these important infections in dairy cows.     

Small mammal virology.

Most viral infections in small mammals are transient and rarely produce clinical signs. When clinical signs do appear, they are often of a multifactorial etiology such as respiratory infection with Sendai virus and the bacteria M. pulmonis in rodents. Diagnosis is generally made based on clinical signs, while therapy involves treatment for concurrent bacterial infections and supportive care. Small mammals may carry zoonotic viruses such as LCMV, but natural infections are uncommon. Viral diseases are rare (or largely unknown) for hedgehogs, chinchillas, and prairie dogs, while no known naturally occurring, clinically relevant viral diseases exist for gerbils and sugar gliders. This article is intended to aid the clinician in identifying viral infections in small mammals and to help determine the significance each virus has during clinical disease.     

ParaCalc®--a novel tool to evaluate the economic importance of worm infections on the dairy farm

Subclinical infections with gastrointestinal nematodes and liver fluke are important causes of production losses in grazing cattle. Although there is an extensive compilation of literature describing the effect of these infections on animal performance, only a few attempts have been made to convert these production losses to an economic cost. Here, we propose a novel tool (ParaCalc(?)), available as a web-application, to provide herd-specific estimates of the costs of these infections on dairy farms. ParaCalc(?) is a deterministic spread-sheet model where results from diagnostic methods to monitor the helminth infection status on a herd and anthelmintic usage are used as input parameters. Default values are provided to describe the effects of the infections on production and the cost of these production losses, but the latter can be adapted to improve the herd-specificity of the cost estimate. After development, ParaCalc(?) was applied on input parameters that were available for 93 Belgian dairy herds. In addition, the tool was provided to 6 veterinarians and their user experiences were evaluated. The estimated median [25th-75th percentile] cost per year per cow was € 46 [29-58] and € 6 [0-19] for gastrointestinal nematode and liver fluke infection, respectively. For both infections, the major components in the total costs were those associated with milk production losses in the adult cows. The veterinarians evaluated ParaCalc(?) as a useful tool to raise the farmers' awareness on the costs of worm infections, providing added value for their services. However, the score given for user-friendliness was diverse among users. Although the model behind ParaCalc(?) is a strong simplification of the real herd processes inducing economic losses, the tool may be used in the future to support economic decisions on helminth control.     

Eye infections due to Listeria monocytogenes in three cows and one horse.

A retrospective study was conducted to determine case histories, microbiological characteristics, and molecular subtypes associated with Listeria monocytogenes infections of the eye in large animals. For selected cases, environmental L. monocytogenes contamination patterns on case farms were also evaluated to probe for potential sources and spread of listerial eye infections. Records of 170 L. monocytogenes isolates from animal infections were reviewed to determine the fraction of isolates associated with eye infections (conjunctivitis, keratitis, and uveitis) of animals and to gather information on the clinical history of these cases. Overall, 4 of 170 Listeria monocytogenes isolates were associated with eye infections; 3 of these had occurred in cows and 1 in a horse. Molecular subtyping (by EcoRI ribotying) showed that 4 different L. monocytogenes subtypes were isolated from these 4 cases; the same ribotypes had previously been found among invasive animal listeriosis infections. Although a variety of L. monocytogenes subtypes were isolated from environmental sources, on 1 farm, the same ribotype associated with the eye infection was also isolated from a fecal sample of a healthy animal and from a soil sample. The data reported in this study further suggest that L. monocytogenes can be a cause of eye infections in several animal species. Listerial eye infections do not seem to require specific pathogen-related virulence characteristics but rather seem to be a function of environmental or host factors, such as direct exposure of the eyes of susceptible animals to high numbers of the pathogen. Although listerial eye infections are rarely diagnosed because of its ubiquitous nature, L. monocytogenes may have to be considered more commonly as a causative agent of eye infections in ruminants and horses.     

BSAVA EDUCATION COMMITTEE COMMISSIONED ARTICLE: Anaerobic bacteria: a cause of infection?

This review article considers the evidence available for a significant role of obligate anaerobes in infections of small animals. The presence of anaerobes in the normal flora and the meaning of the terms aerobe and anaerobe both in relation to the bacterial metabolism and laboratory culture is discussed. The reported findings of anaerobes in clinical veterinary conditions are reviewed. The particular importance of the non-sporing (non-clostridial) anaerobes in traumatic and endogenous infections and the mixed nature, both in terms of different anaerobes and mixed aerobes and anaerobes of such infection are considered. Some experimental evidence for the pathogenicity of obligate anaerobes and their complex role in mixed infections is given. Observations on the use of antibiotics for treatment of suspected anaerobic infections are discussed and the possible implications to laboratory procedures for antibiotic sensitivity testing.     

Nosocomial infections.

Nosocomial infections and antimicrobial resistance are topics that have been intensely studied in human medicine because of their significant impact on human health. In recent years, concerns have been raised that the use of antibiotics in veterinary medicine, animal husbandry, and agriculture may be contributing to the development of resistance in common bacterial species affecting human beings. Although there is inadequate proof at this time that the resistance is transmitted from animals to people, if antibiotics continue to be used indiscriminately in veterinary medicine, veterinarians may find themselves facing regulations restricting the use of some antibiotics. Nosocomial infections have been reported in veterinary medicine and are likely to increase in prevalence with the increase in intensive care practices in many hospitals. Prolonged hospitalization and the use of invasive devices and procedures increase the risk of nosocomial disease. As in human medicine, organisms isolated in the nosocomial infections reported in veterinary patients have an increasingly broad spectrum of antimicrobial resistance. Despite these findings, the use of empiric and prophylactic antibiotic therapy is still widespread in veterinary medicine. Nosocomial infections and antimicrobial resistance may have a serious impact on the future of [table: see text] veterinary medicine, because the cost and ability to treat our patients may be affected by the loss of access to or effectiveness of antimicrobial drugs. Despite the millions of dollars spent on research to reduce the incidence of nosocomial infections in human patients, the strategies that have consistently proven successful are simple and inexpensive to implement. The most important factor in preventing nosocomial infections is improving the hygiene practices of health care providers. Hand-washing or the use of disposable gloves can dramatically reduce the transmission of bacteria between patients. Aseptic technique should be used in the placement and management of all invasive devices. All staff members should be educated on the risks and symptoms associated with nosocomial infections so that cases can be detected early and treated appropriately. We in the veterinary profession have the opportunity to learn from the experiences of the human medical profession and can take steps to prevent the escalation of nosocomial infections and their impact on our profession.     

Public health risk from avian influenza viruses

Since 1997, avian influenza (AI) virus infections in poultry have taken on new significance, with increasing numbers of cases involving bird-to-human transmission and the resulting production of clinically severe and fatal human infections. Such human infections have been sporadic and are caused by H7N7 and H5N1 high-pathogenicity (HP) and H9N2 low-pathogenicity (LP) AI viruses in Europe and Asia. These infections have raised the level of concern by human health agencies for the potential reassortment of influenza virus genes and generation of the next human pandemic influenza A virus. The presence of endemic infections by H5N1 HPAI viruses in poultry in several Asian countries indicates that these viruses will continue to contaminate the environment and be an exposure risk with human transmission and infection. Furthermore, the reports of mammalian infections with H5N1 AI viruses and, in particular, mammal-to-mammal transmission in humans and tigers are unprecedented. However, the subsequent risk for generating a pandemic human strain is unknown. More international funding from both human and animal health agencies for diagnosis or detection and control of AI in Asia is needed. Additional funding for research is needed to understand why and how these AI viruses infect humans and what pandemic risks they pose.     

A review of the interaction of Bacillus anthracis with cells of the innate immune response

Bacillus anthracis spores cause natural infections and can be used as biological weapons.The innate immune response is the first line of defence against invading pathogens and is likely to play a central role in this acute infection.To date the immune evasion mechanisms of B. anthracis are not well understood. Infection by inhalation with B. anthracis, the etiological agent of anthrax, is almost always lethal, yet cutaneous infections usually remain localized and resolve spontaneously in the majority of cases. Neutrophils are typically recruited to cutaneous but seldom to other forms of anthrax infections, raising the possibility that neutrophils kill B. anthracis. This is an overview of the interaction of B. anthracis with innate immune cells which also focuses on recent data on the role neutrophils play in anthrax pathogenesis. These data suggest that the timely recruitment of neutrophils can control the cutaneous and possibly other forms of B. anthracis infections and that the neutrophil granule proteins, a-defensins, play an important role in the potent anti-B. anthracis activity of neutrophils.     

Localized cowpox infection in a 5‐month‐old Rottweiler

Cowpox virus (CPXV) infections are a sporadic cause of localized or disseminated skin disease in domestic animals and humans in Europe. Rodents are considered the primary reservoir host for CPXV. Cats can become infected by close contact with rodents and are the most important source of human infections. Recently, public awareness has also been drawn to CPXV infections by an outbreak of rat to human infections in central Europe. In dogs, CPXV infections are rare. Here we report a case of a 5‐month‐old Rottweiler with a focal nodule on the muzzle. The lesion was fully excised, and recovery was uneventful. The preliminary diagnosis of a CPXV infection was established by the characteristic inclusion bodies on histopathological examination. The diagnosis was confirmed by electron microscopy and polymerase chain reaction (PCR). Sequencing of the PCR product led to a 231 bp sequence of the orthopoxvirus HA gene that was identical to a CPXV strain previously isolated from a cat. This is the third documented case of a canine CPXV infection.     

Changing climate and changing vector-borne disease distribution: the example of Dirofilaria in Europe

Climatic changes, together with an increase in the movement of dogs across Europe, have caused an increase in the geographical range of Dirofilaria infections. The present paper is focuses on northeastern European countries, where survey data have shown an increase of Dirofilaria repens infections both in animals and humans. A growing degree day-based forecast model has been developed to predict the occurrence. The model is based on evidence that there is a threshold of 14 °C below which Dirofilaria development will not proceed in mosquitoes, there is a requirement of 130 growing degree-days (GDDs) for larvae to reach infectivity, and there is a maximum life expectancy of 30 days for a mosquito vector. The output of this model predicted that the summer temperatures (with peaks in August) are sufficient to facilitate extrinsic incubation of Dirofilaria even at latitudes of 56 °N and longitudes of 39 °E. Despite the fact that both Dirofilaria immitis and D. repens have the same temperature requirement for extrinsic incubation in mosquitoes, empirical data has shown that D. repens is the main cause of dirofilarial infections in both humans and animals. Clinical signs are absent in most canine infections with D. repens. Furthermore, diagnosis is problematic and in-clinic serological tests, such as those for D. immitis, do not exist. Therefore, most infections go undiagnosed, allowing the infection to spread undetected.