Porcine Proliferative Enteropathy Research Articles

Seroprevalence of Lawsonia intracellularis, Mycoplasma hyopneumoniae and PCV2 in commercial pig farms in Russia

Porcine circovirus type 2 (PCV2), Mycoplasma hyopneumoniae and Lawsonia intracellularis are economically important pathogens in modern pig breeding and rearing, worldwide. PCV2 infection can be associated with a wide range...

Fermented liquid feed—Microbial and nutritional aspects and impact on enteric diseases in pigs

The use of liquid feed in pig nutrition has recently gained interest due to several reasons: (1) the political wish of decreasing the use of antibiotics in pig production; (2) the current fluctuations in feed prices what makes liquid feed, with the possibility of using cheap liquid ingredients, an interesting feeding strategy; (3) the policies aiming at increasing production of renewable biofuel with a corresponding increase in liquid co-products from the bioethanol industry, suitable for liquid feeding; (4) environmental policies aiming at decreasing disposal of waste, for example, liquid co-products from the food/pharmaceutical/biofuel industry, that can be included in liquid feeding. In order to obtain fermented liquid feed (FLF) of good microbial quality, that is, biosafe, fresh feed and water are mixed with material from a previous successful fermentation, which acts as inoculum for the new mixture. Several factors affect the microbial and nutritional characteristics of the final product and therefore knowledge on the impact of these factors on the characteristics of the mixture is crucial. The initial hours of incubation are characterized by high pH, low numbers of lactic acid bacteria and yeasts, high numbers of Enterobacteriaceae, and low concentration of lactic acid, whereas at later hours of incubation, the pH decreases, the number of lactic acid bacteria and yeasts, and the concentration of organic acids and ethanol increase, whereas the Enterobacteriaceae counts decrease. A reported undesirable consequence of fermentation is the observed degradation of free lysine and concomitant cadaverine production during fermentation of liquid feed. However, the extent of this degradation is affected by various factors, including feed processing and temperature of incubation. Coliform bacteria are related to free lysine degradation. The possible contribution of other microorganisms present in the FLF to this degradation is uncertain, though. Liquid fermentation has the potential of improving the nutritional value of feed ingredients. Data show that fermentation can improve digestibility of various nutrients, e.g., organic matter, nitrogen, amino acids, fibre, and calcium. The conditions of fermentation and the ingredients used are crucial factors in order to benefit from this, though. Further, there are some strategies that can help improving the microbial and nutritional characteristics of FLF, such as addition of starter cultures, organic acids, or enzymes. Other strategies can help avoiding degradation of the amino acids, like adding the free amino acids immediately prior to feeding. The effect of FLF on gastrointestinal health of pigs is one of the subjects being investigated in the last years. Feeding FLF of good quality results in reduction of the number of enteric pathogens like coliforms and Salmonella, and the few published studies on its effect on important pig diseases like porcine proliferative enteropathy and swine dysentery also indicate reduction of the incidence of these diseases in pigs fed FLF.

Proliferative enteropathy (PE)-induced changes in the calbindin-immunoreactive (CB-IR) neurons of inferior mesenteric ganglion supplying the descending colon in the pig.

A subpopulation of the pig inferior mesenteric ganglia (IMG) neurons projecting to the colon exhibit calbindin-like immunoreactivity. It is not known if there are any changes in the chemical coding patterns of these neurons during porcine proliferative enteropathy (PE). To answer this question, juvenile Large White Polish pigs with clinically diagnosed Lawsonia intracellularis infection (PE; n = 3) and a group of uninfected controls (C; n = 3) were compared. The retrograde tracer fast blue (FB) was injected into the descending colons of all animals and then tissue comprising IMGs from both groups was processed for double-labeling immunofluorescence with calbindin-D28k (CB) in combination with either tyrosine hydroxylase (TH), neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP), nitric oxide synthase, Leu-enkephalin, substance P, vesicular acetylcholine transporter, galanin, or pituitary adenylate cyclase-activating polypeptide. Immunohistochemistry revealed changes in the chemical coding pattern of calbindin-immunoreactive neurons in the inferior mesenteric ganglia of the pig. In control animals, FB/CB-positive neurons were immunoreactive to TH, NPY, SOM, and VIP. In the experimental group, TH-expressing neurons were unaffected, NPY-expressing neurons were increased, whereas the number of neurons immunoreactive to SOM or VIP was reduced. Changes in chemical coding of CB neurons during PE may play an important role in adaptation of these IMG cells under pathological conditions.

Characterization of the interferon gamma response to Lawsonia intracellularis using an equine proliferative enteropathy challenge (EPE) model

Lawsonia intracellularis is the etiological agent of infectious intestinal hyperplasia for which several clinical diseases have been described including proliferative enteropathy (PE), intestinal adenomatosis, and ileitis. While initially recognized as the causative agent of PE in pigs, L. intracellularis is now viewed as an emerging cause of intestinal hyperplasia in a wide range of mammalian species, including horses. Equine proliferative enteropathy (EPE) has been reported worldwide though definitive diagnosis is difficult and the epidemiology of the disease remains poorly understood. Weanlings, in particular, appear to be most at risk for infection, though the reasons for their particular susceptibility is unknown. Using an infectious challenge model for EPE, we demonstrate that EPE, like porcine proliferative enteropathy, can exhibit three clinical forms: classical, subclinical and acute. Out of six pony weanlings, one developed signs of classic EPE, one developed acute EPE, and two developed subclinical EPE. Attempts to induce pharmacological stress through the use of dexamethasone failed to have any effect on outcome. Peripheral blood cells collected from those weanlings that developed clinical EPE exhibited decreased expression of interferon-gamma (IFN-γ) following in vitro stimulation with L. intracellularis. By contrast, those weanlings that did not develop clinical disease generated a robust IFN-γ response. These results indicate IFN-γ likely plays a significant role in protection from disease caused by L. intracellularis in the equid.

Immunohistochemical detection of Lawsonia intracellularis in tissue sections from pigs

The aim of the present study was to develop an immunohistochemical method (IHC) for detection of Lawsonia intracellularis (L. intracellularis) in formalin-fixed, paraffin embedded sections of intestines from pigs and to implement this method in differential diagnosis of swine diseases with diarrhea in postweaning pigs. The study was conducted on 165 sections of intestines (ileum, caecum and colon) collected from 76 pigs, representing 42 Polish pig farms. The animals included in the analysis suffered from diarrhea, with bloody or grey to brown feces, and were suspected of porcine proliferative enteropathy (PPE). Sections of intestines were analyzed for the presence of L. intracellularis by polymerase chain reaction (PCR) and IHC. Among 165 intestinal samples from pigs with diarrhea, L. intracellularis DNA was detected by PCR in 33 (20.0%) samples. In this group, 30 samples (18.2% of all the samples tested) were also found positive in IHC, while only 3 (1.8%) were IHC-negative. One hundred thirty-two (80.0%) samples were negative in both tests. The PCR- and IHC-positive samples originated from 11 pigs, 4- to 20-week old, from 8 farms. L. intracellularis antigen was visualized by IHC mostly in intestinal crypts and/or in mononuclear cells of the lamina propria). The positive signal in epithelial cells was observed close to the luminal borders, creating typical specifically stained rims around the crypt lumina. The results of the present study further confirm the usefulness of IHC in the detection of L. intracellularis antigen in the intestinal tissues.

Current infection patterns of porcine proliferative enteropathy in Great Britain and the Republic of Ireland

Veterinary RecordVolume 167, Issue 9 p. 343-344 Paper Current infection patterns of porcine proliferative enteropathy in Great Britain and the Republic of Ireland I. Hands BVSc, MRCVS, Corresponding Author I....

Essential oils and aromatic plants in animal feeding – a European perspective. A review.

AbstractThe last two decades have seen a substantial increase in the use of aromatic herbs and essential oils as feed additives in animal nutrition. One of the main reasons for this trend is to substitute antibiotic growth promoters, which have been completely banned as feed additives in the European Union since 2006 because they are suspected of contributing substantially to increasing resistance among human pathogens. Recent investigations have shown significant antimicrobial effects of several essential oils and essential oil compounds against enteropathogenic organisms in farm animals. Porcine proliferative enteropathy caused by specific Escherichia coli strains could be controlled by in‐feed application of carvacrol‐rich essential oils, and the effect of some essential oil components against Clostridium perfringens and necrotic enteritis was confirmed in poultry. In ruminants, an improvement of the digestion was observed, resulting in reduced methanogenesis and nitrogen excretion. In addition, the antioxidative activity of aromatic plants and essential oil compounds contributes to the stability and palatability of animal feed and has, moreover, resulted in an improved shelf‐life and quality of animal products, due to reduced oxidation. The ‘growth‐promoting effect’ of essential oils (feed conversion rate, daily weight gain, etc.) is not as evident, since a large number of publications are (commercial) product‐driven, lacking data on the starting material. Nonetheless, the overall efficacy of essential oils and aromatic herbs, especially their non‐nutritive value with impact on the health status and benefit of animals and humans (via the food chain), is encouraging further research and development in this field. Copyright © 2009 John Wiley & Sons, Ltd.

In-feed macrolide Leucomycin (Leucomag 30% PR) for prevention of proliferative enteropathy in experimentally infected pigs

The aim of this study was to evaluate the efficacy of orally administered leucomycin at 90 and 180ppm for the prevention of porcine proliferative enteropathy (PPE) in experimentally infected pigs. A total of 90 commercial five-week-old pigs were randomly assigned to receive leucomycin in feeding at 90 (T2), 180ppm (T3), or untreated (T1). All animals in the treated groups received medicated feed for 14 days starting one day before inoculation. Each pig was inoculated intragastrically with approximately 4.5x10(9) Lawsonia intracellularis in the form of porcine intestinal mucosal homogenate. Body weight, feed consumption and clinic signs were evaluated throughout the study. Necropsies and gross evaluation of intestines were performed in all animals on day 23 post-inoculation (pi) or at death, and ileum samples were collected for immunohistochemistry (IHC) for L. intracellularis. Clinical presentation of the disease was more evident in the non-medicated group (T1) than in the medicated ones (T2, T3) between days 16 and 21pi. Average daily gain, average daily feed consumption and feed conversion efficiency were better in groups treated with either dose of leucomycin. The total intestine lesion length per group (T1, T2 and T3) was 869, 473 and 331cm, respectively. The majority of the animals (84.4%) were positive for L. intracellularis antigen in ileum sections stained by IHC. Under the conditions of this study, leucomycin administered in feed at 90 and 180ppm for 14 days was effective in improving performance of pigs inoculated with intestinal homogenate containing L. intracellularis.

A Quantitative Polymerase Chain Reaction Assay for Detection and Quantification of Lawsonia Intracellularis

Lawsonia intracellularis, a causative agent of porcine proliferative enteropathy, is an obligate intracellular bacterium that is difficult to culture, propagate, and quantify. The intestinal epithelial cell line (IEC-18, derived from rat small intestine crypt cells) has been used to isolate and propagate this pathogen. However, the lack of rapid and simple quantification methods has led to mixed results when using the rat cell line, complicating Lawsonia studies. To overcome these limitations, a SYBR green quantitative polymerase chain reaction (qPCR) assay targeting a unique hypothetical protein was developed for detecting and quantifying L. intracellularis in IEC-18 rat epithelial cells, porcine fecal samples collected from different farms, and experimentally infected pigs. The method was optimized to detect as few as 3 copies per qPCR reaction of the bacterium growing in IEC-18 cells, providing a new and necessary approach to assess the growth of L. intracellularis in these cell lines. Furthermore, the qPCR assay was successful in detecting L. intracellularis in fecal samples collected from pigs with and without a history of Lawsonia infections, as well as in experimentally infected pigs, which further confirmed the suitability of the qPCR assay for studying the epidemiology of this pathogen.

Early Pathogenesis in Porcine Proliferative Enteropathy caused by Lawsonia intracellularis

The intestinal bacterium Lawsonia intracellularis, the cause of proliferative enteropathy (PE) in pigs, is believed to infect mitotically active epithelial cells of the intestinal crypts and then multiply and spread in these cells as they divide. Further spread of infection is thought to occur by shedding of bacteria from infected crypts followed by infection of new crypts. The early stages of the pathogenesis of PE, from 0 to 48 hours post-infection (hpi), have not been studied in vivo. In the present study pigs were inoculated with L. intracellularis and killed from 12 hpi to 5 days post-infection (dpi). The localization of L. intracellularis was determined immunohistochemically and by fluorescence in-situ hybridization. At 12 hpi L. intracellularis was found within epithelial cells at the tips of villi, indicating infection of a range of epithelial cells including mature differentiated enterocytes. Furthermore, early invasion of the intestinal connective tissue was observed; with the presence of single bacteria in the lamina propria 12 hpi, and with a further spread of bacteria in the lamina propria observed at 5 dpi, suggesting an active role for the lamina propria in the course of infection.

An Atypical Porcine Proliferative Enteropathy of Malgrowth Piglets

Two 60-day-old pigs showing clinical signs of malgrowth and diarrhea were diagnosed as atypical porcine proliferative enteropathy (PPE). The intestinal mucosal lesions in the piglets were characterized by the adenomatous proliferation of the crypt epithelium together with growth of small curved bacteria within the enterocytes. The lesions could be seen in the ileum and other portions of the intestine histologically, although no significant thickening of the gut wall could be observed grossly in the present case. The macroscopic findings are extremely important for the diagnosis of PPE, however, this paper shows that the histopathological and/or immunohistochemical findings were also critical to identify the disease.

Porcine proliferative enteropathy: An important disease with questions remaining to be solved

Proliferative enteropathy caused by the intracellular bacterium Lawsonia intracellularis is an endemic disease with high herd prevalences reported worldwide. The infection has a considerable impact on pig production and herd economics and, with the development of new diagnostic techniques, L. intracellularis is being identified in an increasing number of pig herds and a wider range of species. This paper reviews current knowledge of the disease, with a focus on the epidemiology in pigs. The prevalence of infection, transmission, predisposing factors, microbial features, pathogenesis, clinical signs, diagnosis, treatment and control are discussed. The disease is mainly controlled by antibiotic treatment and vaccination at herd level. In the development of effective measures to prevent the spread of the infection, increased knowledge of the transmission and persistence of the microorganism are crucial.

Reduced use of antimicrobials after vaccination of pigs against porcine proliferative enteropathy in a Danish SPF herd

The present study explored whether the use of group medication with antibiotics in a Danish pig herd was reduced after vaccination of the pigs against proliferative enteropathy (PE) caused by Lawsonia intracellularis. 7900 pigs originating from a single commercial sow herd were vaccinated against L. intracellularis, whereas 7756 pigs were kept as non-vaccinated controls. The pigs were included batch-wise in the study with every second batch being vaccinated. In the vaccinated batches, the consumption of oxytetracykline to treat PE was reduced by 79%, with a significantly lower number of pigs being treated (P < 0.0001). Vaccination also resulted in a highly significant improvement of average daily weight gain (+ 46 g/day; P = 9.55 × 10-31) and carcase weight (+ 1.25 kg; P = 4.54 × 10-05) as well as a shortened fattening period (-8 days; P = 2.01 × 10-45).

Identifying obstacles to reducing the use of antibiotics to control porcine proliferative enteropathy

Proliferative enteropathy (PE) is an enteric disease of pigs that results in diarrhoea, reduced growth rate, reduced feed conversion efficiency and sometimes death. A survey of 13 pig veterinary practitioners in Australia was conducted to determine: (1) PE control strategies (antibiotics and vaccination), (2) how the efficacies of these strategies are evaluated and (3) how reliance on antibiotics could be reduced by increasing vaccine adoption. Antibiotics were routinely prescribed in the diets of weaner, grower and finisher pigs by 9/13, 10/13 and 8/13 veterinarians, respectively, if vaccination was not implemented. Water-soluble antibiotics were prescribed less frequently than in-feed antibiotics. Efficacy of control strategies was assessed most often through reduced clinical signs (diarrhoea, 'tail-ender' pigs, death) and reduced lesion incidence at abattoir postmortem inspection. Twelve practitioners had recommended PE vaccination to their clients in the previous 6 months. Barriers to continued vaccine implementation included perceived lack of efficacy for pigs housed in bedded systems, high cost relative to medication and difficulties in vaccinating pigs post-weaning.

SEROLOGICAL PROFILES FOR LAWSONIA INTRACELLULARIS IN SWINE FARMS

Farm prevalence studies in several countries in Europe, Asia and Northern America indicated that 24 to 47% of pig farms had a serious incidence with PPE in the past years. Herd prevalence for finishing pigs in other EU countries has been estimated to range between 88 and 100% (1, 2, 3). Porcine proliferative enteropathy (PPE) known as porcine proliferative ileitis is produced by Lawsonia intracellularis. PPE affects animals from 6 weeks of age and produce important damage, diarrhoea and poor performance in growing pigs. PPE are observed most commonly in the postweaned pig between 6 and 20 weeks of age. The purpose of this study was to determine the prevalence of L. intracellularis from 12 swine farms by enzyme-linked immunosorbent assay. Materials and method There were taken in study 12 pig farms from west side of Romania with young pigs (35-70 days of age) and fattening (100-150 days of age). In total 61 blood samples from 12 farms were analyzed by using a blocking ELISA by kit Bioscreen Ileitis antibody ELISA (Synbiotics Europe SAS, France). Results and discussions In 10 from 12 studied farms we found one or more positive samples. Our results show that the most affected categories were fattening (100-150 days). From 61 tested samples 31 samples were positive (49,1%), 11 samples had value of percentage of inhibition (PI) between 20 and 30 (18%), and 19 samples were negative (31,1%). The shift of seropositivity to higher age categories (fattening) may be principally connected with the very early antibiotic therapy of swine dysentery in the post-weaning period. In relation to the infection dynamic in the herd demonstrated an increase in the antibodies prevalence in animals from nursery to fattening. Usually seroconversion can be detected between 16 and 24 weeks of age by an increasing percentage of inhibition (PI). A positive test result reflects the exposure of pigs to infection L. intracellularis at least 2 to 3 weeks before (2). The low prevalence in the antibodies detection in weaning pigs suggests a low passive immunity.

Proliferative enteropathy (PPE)-induced changes in the expression of DBH, VAChT and NOS in the neurons of intramural ganglia of the porcine ileum

As enteric neurons are regarded to be highly adaptive in their response to various pathological states, including inflammation, it appears to be of interest to study the chemical coding of neurons in the intramural ganglia of the ileum wall in the course of porcine proliferative enteropathy (PPE) evoked by &lt;I&gt;Lawsonia intracellularis.&lt;/I&gt; The study was performed on 12 juvenile pigs of the Large White Polish breed. The pigs were divided into the control (C, &lt;I&gt;n&lt;/I&gt; = 6) group and the group consisting of pigs with clinically diagnosed &lt;I&gt;Lawsonia intracellularis&lt;/I&gt; infection (E, &lt;I&gt;n&lt;/I&gt; = 6). In E group animals the infection was confirmed with a PCR-based test. All the animals were sacrificed and segments of the ileum being pathologically changed were processed for double-labelling immunofluorescence using antibody against protein gene-product 9.5 (PGP 9.5) combined with antibody for dopamine &amp;beta;-hydroxylase (D&amp;beta;H), vesicular acetylcholine transporter (VAChT) or nitric oxide synthase (NOS). Immunohistochemistry revealed in the inner submucous plexus (ISP) and outer submucous plexus (OSP) an increase of the number of neurons containing D&amp;beta;H and VAChT in the E group. Interestingly, a decrease in the number of D&amp;beta;H- and VAChT-positive neurons in meynteric plexus (MP) ganglia of the E group animals was observed. The most remarkable difference in the chemical coding of enteric neurons between the control and PPE-suffering pigs was a significant increase of the number of NOS-positive nerve cells in the MP and OSP of the infected animals. The present results show that acetylcholine, catecholamines and NO may be involved in the regulation of functions of the porcine enteric nerve pathways not only under physiological, but also pathological conditions.

Lawsonia intracellularisin rodents from pig farms with the occurrence of porcine proliferative enteropathy

Lawsonia intracellularis is an obligate intracellular bacterium causing proliferative enteropathy in certain species of domestic, laboratory and captive animals. The aim of our study was to detect L. intracellularis in free-living rodents from pig farms in the Czech Republic. Lawsonia intracellularis was demonstrated, using nested polymerase chain reaction, in the intestinal mucous membranes of 107 (36%) out of 296 small terrestrial mammals collected. In rodents, the bacterium was detected in 91 of 213 house mice, one of six brown rats, eight of 51 striped field mice, three of 12 yellow-necked mice and three of nine common voles. Moreover, one of one tested lesser white-toothed shrew (Insectivora) was positive. In 17 out of 69 (25%) rodents tested, serum IgG antibodies against L. intracellularis were detected using an indirect immunofluorescence antibody test. All seropositive animals were house mice. Free-living rodents may be serving as host or reservoir species and may be playing a role in the spread of L. intracellularis both within pig farms and in its transmission between farms and into the natural environment. This is the first detection of L. intracellularis in free-living small mammalian terrestrial species.

Infection of Different Strains of Mice with Lawsonia intracellularis Derived from Rabbit or Porcine Proliferative Enteropathy

This report describes intestinal lesions in five strains of mice infected orally with Lawsonia intracellularis-infected tissue homogenates from rabbits or pigs (RLI and PLI). BALB/cA, C3H/HeJ, C57BL/6J and ICR mice were susceptible to infection with RLI, whereas only C3H/HeJ, C57BL/6J and ICR strains were susceptible to PLI. In susceptible mice, crypt epithelial hyperplasia occurred in association with an inflammatory reaction, as in proliferative enteropathy (PE) in other species. The intestinal changes in the infected mice varied from mild to severe. Unlike rabbit or porcine PE, in which the changes are confined to the ileum, the lesions in mice were located in the caecum. Immunolabelling of L. intracellularis antigen was abundant in early infection when the epithelial hyperplasia was mild or absent. When the hyperplasia had become severe, however, immunolabelling was weak. For this reason, it is suggested that transitory infection of the epithelium induces epithelial hyperplasia. Genetic differences between mouse strains appeared to play an important role in the response to L. intracellularis infection. Moreover, the susceptibility of BALB/cA mice to RLI but not to PLI suggests that there are significant biological differences between L. intracellularis isolates from rabbit PE and porcine PE.

Development and validation of an enzyme-linked immunosorbent assay for the diagnosis of porcine proliferative enteropathy

The objective of this study was to develop an indirect enzyme-linked immunosorbent assay (ELISA) using a sonicated pure culture of Lawsonia intracellularis as the antigen (So-ELISA). A total of 332 serum samples, consisting of 232 experimentally infected animals and 100 animals naturally infected with L. intracellularis, were used to assess the diagnostic sensitivity. Three hundred and fifty-five sera from uninfected animals were used to determine the diagnostic specificity. The receiver operating characteristic and mean +3 standard deviation of optical density (OD) values from uninfected animals were used for selecting cut-off points. The diagnostic accuracy of So-ELISA was considered to be high as the area under the curve index was 0.991 with 0.0029 standard error. The optimal cut-off for So-ELISA was set at 0.45 OD with 89.8% sensitivity and 99.4% specificity based on a combination of good sensitivity and high specificity. No cross-reactivity was found in sera from pigs exposed to Brachyspira pilosicoli, B. hyodysenteriae, Campylobacter mucosalis, C. jejuni, or C. coli. Inter- and intracoefficient of variation of all control sera tested with So-ELISA was less than 10%. The observed agreements between So-ELISA and the immunoperoxidase monolayer assay tested with experimental challenge animals and field samples were 95.08% with 0.88 kappa and 90.65% with 0.74 kappa value, respectively. So-ELISA was able to detect the seroconversion of infected animals at 2 to 4 weeks after exposure to L. intracellularis. Based on the validation results, So-ELISA could be used as an alternative serology for proliferative enteropathy diagnosis.

Antimicrobianos para o controle da enteropatia proliferativa suína

A enteropatia proliferativa suína (EPS), causada pela bactéria Lawsonia intracellularis, causa perdas econômicas importantes mundialmente, devido à diarréia e baixa taxa de crescimento de suínos na recria (forma crônica) e à morte súbita de animais de terminação e reposição (forma aguda). Programas de controle têm sido focalizados na medicação com antibióticos na ração. Essencialmente, a eficiência de um antimicrobiano pode ser testada in vitro ou in vivo. Testes in vivo podem ser desenvolvidos utilizando-se animais natural ou experimentalmente infectados. No caso de infecção experimental, o inóculo pode ser preparado com culturas puras de L. intracellularis ou com homogenado de mucosa intestinal de leitões enfermos. O uso de antimicrobianos tem-se mostrado eficiente em reduzir os sinais clínicos da EPS, resultando em melhor performance dos animais tratados em relação aos não-medicados e na redução da eliminação fecal da bactéria e da extensão e severidade das lesões macroscópicas. A maioria dos fármacos eficientes que são discutidas no texto são dos grupos dos macrolídeos, das tetraciclinas, lincosamidas e pleuromutilinas. Todos esses fármacos agem bloqueando a síntese protéica de bactérias.