Unbridled Threat of Gas Gangrene in a Patient With Uncontrolled Diabetes Mellitus: A Compelling Case Report of Clostridium perfringens Infection

Clostridium perfringens, a Gram-positive anaerobic bacterium, is well-known for its association with gas gangrene, a severe and rapidly progressing infection characterized by tissue gas production and necrosis. In this case report, we present the instance of a 64-year-old male with poorly controlled diabetes mellitus who developed a C. perfringens-related infection following a traumatic foot wound. The report emphasizes the critical significance of early diagnosis and aggressive treatment in C. perfringens infections, particularly in patients with underlying risk factors. Detailed accounts of clinical findings, laboratory results, computed tomography, and surgical interventions are provided. A multidisciplinary approach proved essential for successful management. The inherent scholarly value of this case is substantiated by its meticulous documentation of the clinical trajectory, diagnostic modalities, and treatment modalities employed. The intricate collaboration across diverse medical disciplines, the uncommon manifestation of the infection following a traumatic foot wound, and the favorable outcome achieved through prompt and multidisciplinary intervention collectively contribute to the exceptional nature and didactic significance of this case. The dissemination of such clinical experiences assumes paramount importance in advancing medical scholarship, cultivating awareness, and engendering a profound comprehension of the complexities associated with C. perfringens infections, thereby enriching the wider scientific and medical community.

Survival in a Case of Emphysematous Cholecystitis With Sepsis Caused by Clostridium perfringens

A 77-year-old man presented to the Department of Internal Medicine with a chief complaint of abdominal pain. During the outpatient examination, a computed tomography (CT) scan showed gallstones. The patient developed worsening abdominal pain and fever and was admitted to the emergency department. He was diagnosed with cholecystitis and hospitalized. Treatment with antimicrobial agents was initiated. On the second day of hospitalization, the patient developed a fever of 39°C, hypotension, and oliguria. An emergency CT scan was performed, which showed gas production in the gallbladder. He was diagnosed with emphysematous cholecystitis, and emergency percutaneous transhepatic gallbladder drainage was performed. The patient was transferred to the high-care unit, and intensive care was initiated. On the eighth day, a follow-up CT scan showed an abscess in the gallbladder bed, and drainage was performed percutaneously. His general condition gradually improved, and he was discharged from the hospital on day 24. The patient was readmitted for cholecystectomy three months after the initial admission. The prognosis of sepsis caused by Clostridium perfringens is extremely poor, with a mortality rate of 70%-100%. We present a case of emphysematous cholecystitis successfully treated with multimodal treatment despite the presence of sepsis due to Clostridium perfringens and discuss the possible prognostic factors by reviewing the literature.

Clostridium perfringens Epsilon Toxin Binds to and Kills Primary Human Lymphocytes

Clostridium perfringens epsilon toxin (ETX) is the third most lethal bacterial toxin and has been suggested to be an environmental trigger of multiple sclerosis, an immune-mediated disease of the human central nervous system. However, ETX cytotoxicity on primary human cells has not been investigated. In this article, we demonstrate that ETX preferentially binds to and kills human lymphocytes expressing increased levels of the myelin and lymphocyte protein MAL. Using flow cytometry, ETX binding was determined to be time and dose dependent and was highest for CD4+ cells, followed by CD8+ and then CD19+ cells. Similar results were seen with ETX-induced cytotoxicity. To determine if ETX preference for CD4+ cells was related to MAL expression, MAL gene expression was determined by RT-qPCR. CD4+ cells had the highest amount of Mal gene expression followed by CD8+ and CD19+ cells. These data indicate that primary human cells are susceptible to ETX and support the hypothesis that MAL is a main receptor for ETX. Interestingly, ETX bindings to human lymphocytes suggest that ETX may influence immune response in multiple sclerosis.

Postpartum Septic Shock Due to Clostridium Perfringens From Chorioamnionitis: A Rare Case

Although postpartum infections caused by Clostridium species are relatively rare, they can have severe consequences if not promptly identified and treated. Clostridial uterine infections typically originate as localized chorioamnionitis, stemming from fetal and/or placental tissue infection. The infection may then spread to the uterine wall and endometrial tissues, and in the most severe cases, it may result in sepsis and shock. These infections can cause serious illness and a high mortality rate without proper treatment. We describe the case of a 26-year-old primigravida woman at 39 weeks gestation who presented with active labor. Clostridium perfringens was isolated from her blood culture, which led to an intrapartum fever and postpartum septic shock. The patient was admitted to the intensive care unit and received appropriate management, resulting in a favorable outcome.

An Unusual Fatal Outcome of Laparoscopic Cholecystectomy: A Case Report

Clostridium perfringens (C. perfringens) and Klebsiella oxytoca (K. oxytoca) are pathogenic human bacteria. Clostridium perfringens sepsis with intravascular hemolysis is a catastrophic process with an extremely high mortality rate (70 to 100%). A 74-year-old male submitted to an elective laparoscopic cholecystectomy due to cholelithiasis and develops severe abdominal pain only 10 hours after being discharged from hospital. He was admitted to the emergency department with associated jaundice, fever, and hematuria. On arrival, his hemoglobin level was 9.2 g/dL but fell to 3.4g/dL within two hours. Massive intravascular hemolysis was diagnosed and a liver abscess with gas gangrene was shown in the contrast-enhanced computed tomographic. Despite proper management, a fatal outcome was unavoidable and the patient died eight ours later. Microbiological examination isolated C. perfringens and K. oxytoca. Liver abscesses caused by C. perfringens and K. oxytoca are extremely rare complications of laparoscopic cholecystectomy. Early recognition and prompt antibiotic therapy as well as control of septic focus are essential to minimize this fatal outcome.

Effects of dietary β-1,3-glucan addition on the growth performance, mRNA expression in jejunal barrier, and cecal microflora of broilers challenged with Clostridium perfringens

This experiment aimed to explore the interaction of β-1,3-glucan and Clostridium perfringens on the growth performance, intestinal health and cecal microflora of broilers. A total of 384 one-day-old Arbor Acre broilers were sorted into 4 treatments with 6 replications. There were 2 factors in this trial: dietary β-1,3-glucan addition including 0 and 250 mg/kg, intestinal enteritis challenged with Clostridium perfringens attack or not. Results showed that Clostridium perfringens infection disrupted the integrity of the intestinal mucosa by reducing the jejunal Occludin and Claudin-1 mRNA expression of broiler chickens at 21 d of age (P < 0.05). Meanwhile, when considering Clostridium perfringens as the main effect, it also decreased the mRNA expression of the glucose transporter recombinant sodium/glucose cotransporter 1 (SGLT1) at d 21 and the fatty acid transporter liver fatty acid-binding protein (L-FABP) at d 42 (P < 0.05) as well as affect cecum microbial diversity, especially in relative abundance of Firmicutes and Bacteroidetes. In addition, Clostridium perfringens infection reduced body weight, daily weight gain, and feed-gain ratio (FCR) in broilers at d 42 (P < 0.05). The dietary β-1,3-glucan could alleviate intestinal mucosal damage caused by the Clostridium perfringens to some extent. When considering β-1,3-glucan as the main effect, it increased the SGLT1 at 42 d of age (P < 0.05), and stabilized gut microbiota disorder caused by Clostridium perfringens. More over dietary β-1,3-glucan addition increased body weight at 42-day-old (P < 0.05), and improved daily weight gain and FCR during 1 to 42 d (P < 0.05). In conclusion, dietary β-1,3-glucan could improve growth performance and intestinal health in broilers infected with Clostridium perfringens.

Short and Medium Chain Fatty Acids and Their Derivatives as a Natural Strategy in the Control of Necrotic Enteritis and Microbial Homeostasis in Broiler Chickens

The use of antibiotic growth promoters (AGPs) has historically been the most important prophylactic strategy for the control of Necrotic Enteritis (NE) caused by some Clostridium perfringens toxin types in poultry. During the last five decades, AGPs have also been supplemented in feed to improve body weight gain and feed efficiency as well as to modulate the microbiome (consisting of microbes and their genes both beneficial and potentially harmful) and reduce enteric pathogens, among other benefits. New regulatory requirements and consumer preferences have led to strong interest in natural alternatives to the AGPs for the prevention and control of illnesses caused by enteric pathogens. This interest is not just focused on the direct removal or inhibition of the causative microorganisms but also the improvement of intestinal health and homeostasis using a range of feed additives. A group of promising feed additives is short- and medium-chain fatty acids (SCFA and MCFA, respectively) and their derivatives. The use of SCFA and MCFA, including butyric, caproic, caprylic, capric, and lauric acids, has shown strong effects against NE in broilers both at experimental and commercial levels. These fatty acids also benefit intestinal health integrity and homeostasis. Other effects have also been documented, including increases in intestinal angiogenesis and gene expression of tight junctions. Chemical modifications to improve stability and point of release in the intestine have been shown to improve the efficacy of SCFA and MCFA and their derivatives. The aim of this review is to give an overview of SCFA, MCFA and their derivatives, as an alternative to replace AGPs to control the incidence and severity of NE in poultry.

Effects of dietary glucose oxidase on growth performance and intestinal health of AA broilers challenged by Clostridium perfringens

Arbor Acre (AA) broilers were used as the research object to investigate whether glucose oxidase (GOD) has preventive and relieving effects on necrotic enteritis. The experiment was designed as a factorial arrangement of 2 dietary treatments × 2 infection states. Chickens were fed a basal diet or a diet with 150 U/kg GOD, and were challenged with Clostridium perfringens (Cp) or sterile culture medium. In our study, Cp challenge led to intestinal injury, as evidenced by reducing the average daily gain and the average daily feed intake of AA broilers of 14 to 21 d (P < 0.05), increasing the intestinal jejunal lesion score (P < 0.05), reducing the jejunal villi height and villi height/crypt depth (P < 0.05), upregulating the mRNA expression levels jejunal IFN-γ (P < 0.05). The dietary GOD had no significant effects on the growth performance of each growth period, but significantly decreased the ileal pH, increased the height of villi and the ratio of villi height to crypt depth (P < 0.05) and the expression levels of Occludin and Zonula occludens-1 (ZO-1) at d 21. Moreover, dietary GOD and the Cp challenge significantly altered the composition of 21-d ileal microbiota. The Cp challenge decreased the relative abundance of genus Lactobacillus (P = 0.057), and increased the relative abundance of genus Romboutsia (P < 0.05) and genus Veillonella (P = 0.088). The dietary GOD tended to increase the relative abundance of genus Helicobacter (P = 0.066) and decrease the relative abundance of genus Streptococcus (P = 0.071). This study has shown that the supplementation of GOD could promote the integrity of intestinal barrier and the balance of ileal microbiota, but the effects of GOD on NE broilers and its application in actual production need to be further confirmed.

Enteric Organisms Detected in Feces of Dogs With Bloody Diarrhea: 45 Cases

Bloody diarrhea is a common condition in dogs, but studies evaluating the enteropathogens involved specifically in adult dogs are scarce. In the present study, stool samples from 45 adult dogs with bloody diarrhea were evaluated for the four enteric organisms mainly reported in these cases: canine parvovirus type 2 (CPV-2), Clostridioides difficile, Clostridium perfringens, and Salmonella spp. In addition, the samples were also tested for coronavirus, rotavirus, Giardia spp., and Escherichia coli pathotypes to provide a better understanding of possible co-occurrence. Vaccination status, diet, and clinical outcome were also obtained when available. CPV-2b was identified in 17 dogs (37.8%), being the most frequent cause of bloody diarrhea, including completely vaccinated adult dogs. Toxigenic C. difficile and C. perfringens netF⁺ were detected in 6 (13.3%) and 5 (11.1%) dogs, in some cases in a co-occurrence with other enteric organisms. Three fatal cases of salmonellosis were identified in dogs fed a raw meat-based diet, raising the risks associated with this increasing practice.

A Rare Case of Septic Knee Arthritis Caused by Clostridium perfringens in a Patient With Colostomy

Septic arthritis of the knee is commonly caused by aerobic organisms. Rarely, it can be caused by Clostridium perfringens, usually due to penetrating trauma. This is a rare case of C. perfringens septic arthritis in a patient with colostomy due to hematogenous spread. The patient was treated successfully with a synovectomy and a prolonged intravenous antibiotic course. The case report summarizes the existing literature on the topic and discusses the diagnosis, management, and prognosis of such cases as well.

Supplementing Garlic Nanohydrogel Optimized Growth, Gastrointestinal Integrity and Economics and Ameliorated Necrotic Enteritis in Broiler Chickens Using a Clostridium perfringens Challenge Model

Necrotic enteritis (NE) caused by Clostridium perfringens (C. perfringens) results in impaired bird growth performance and increased production costs. Nanotechnology application in the poultry industry to control NE outbreaks is still not completely clarified. Therefore, the efficacy of dietary garlic nano-hydrogel (G-NHG) on broilers growth performance, intestinal integrity, economic returns and its potency to alleviate C. perfringens levels using NE challenge model were addressed. A total of 1200 male broiler chicks (Ross 308) were assigned into six groups; four supplemented with 100, 200, 300 or 400 mg of G-NHG/kg diet and co-challenged with C. perfringens at 21, 22 and 23 d of age and two control groups fed basal diet with or without C. perfringens challenge. Over the total growing period, the 400 mg/kg G-NHG group had the most improved body weight gain and feed conversion efficiency regardless of challenge. Parallel with these results, the mRNA expression of genes encoding digestive enzymes (alpha 2A amylase (AMY2A), pancreatic lipase (PNLIP) and cholecystokinin (CCK)) and intestinal barriers (junctional adhesion molecule-2 (JAM-2), occludin and mucin-2 (Muc-2)) were increased in groups fed G-NHG at higher levels to be nearly similar to those in the unchallenged group. At 14 d post challenge, real-time PCR results revealed that inclusion of G-NHG led to a dose-dependently decrease in the C. perfringens population, thereby decreasing the birds' intestinal lesion score and mortality rates. Using 400 mg/kg of G-NHG remarkably ameliorated the adverse effects of NE caused by C. perfringens challenge, which contributed to better growth performance of challenged birds with rational economic benefits.

Ankle fracture and necrotizing fasciitis: a common fracture and a dreadful complication

Necrotizing fasciitis is a dreadful complication of the soft tissue. This pathology could be triggered by many factors, such as a fracture. We present a case of case of a necrotizing fasciitis in ankle fracture.

Research Note: Effect of synbiotic supplementation on caecal Clostridium perfringens load in broiler chickens with different necrotic enteritis challenge models

Studies were conducted to determine the efficacy of synbiotic applications to combat the negative effects of necrotic enteritis (NE). An in vitro study was conducted to test the effect of probiotics species supernatants to decrease Clostridium perfringens (CP) proliferation. Lactobacillus reuteri, Enterococcus faecium, Bifidobacterium animalis, and Pediococcus acidilactici culture supernatants decreased the proliferation of CP at 1:1 supernatant-to-pathogen dilution in vitro. Two in vivo studies were conducted to determine the in vivo response of synbiotic supplementation containing the aforementioned probiotic strains on broiler production performance and caecal CP load in broilers induced with NE infection. In experiment 1, 75 broiler chicks were randomly allotted to 3 treatment groups, control (basal diet), ionophore (Salinomycin), and synbiotic (PoultryStar me), from day of hatch, and NE was induced in all birds. There were no significant treatment effects on BW, feed consumption, and feed gain ratio. However, at 35 D, ionophore or synbiotic supplementation increased (P < 0.05) villi height and decreased interleukin (IL)-1 mRNA abundance, while synbiotic supplementation increased (P < 0.05) IL-10 mRNA abundance compared with the control group, respectively. In experiment 2, 360 broiler chicks were randomly allotted to 3 treatments, an unchallenged negative control (control; basal diet), challenged positive control (NE; basal diet), or NE + synbiotic group (synbiotic). At both 21 and 42 D of age, NE birds had decreased (P < 0.05) BW, feed conversion, and jejunal villi height compared with control, while NE + synbiotic birds were not different from control groups. At 42 D of age, NE birds had 2.2 log/g increased CP in the ceca contents compared with control, while synbiotic birds had CP load that was not different than that of the control group. NE + synbiotic birds had significantly greater amounts of bile anti-CP IgA than the control and NE groups. It can be concluded that synbiotic supplementation decreased CP proliferation in vitro and caecal CP load in vivo while improving production parameters during an NE infection in broilers.

Frightening" Resistant Clostridial Myonecrosis: A Case Report

Clostridial myonecrosis is a diffuse necrotizing infection of deep soft tissues. It is known for its acute, rapid progression, poor prognosis, and high mortality. We report a case of traumatic clostridial myonecrosis, a 17-year-old, previously healthy female reported to our department with the complaint of pain in her left arm a week after she suffered a fall from her chair on to her left arm. Due to the injury sustained in the incident, under suspicion of a forearm fracture, a cast was applied to her left arm at a local polyclinic. However, after a few days, she reported unbearable pain, which led to the removal of the cast, and that is when diffuse crepitations due to gaseous accumulation were noted in her entire left upper limb. A week later, X-ray studies failed to reveal any fracture or abnormality. The patient was started on broadspectrum antibiotic coverage with intravenous (IV) benzylpenicillin, rifampicin, and clindamycin for a considerable period of time, but there was no improvement in her condition and the infection continued to spread into adjacent soft tissues, requiring intervention with hyperbaric oxygen therapy.

Sulphonamide inhibition studies of the β-carbonic anhydrase from the bacterial pathogen Clostridium perfringens

The β-carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic bacterium Clostridium perfringens (CpeCA) was recently characterised kinetically and for its anion inhibition profile. In the search of effective CpeCA inhibitors, possibly useful to inhibit the growth/pathogenicity of this bacterium, we report here an inhibition study of this enzyme with a panel of aromatic, heterocyclic and sugar sulphonamides/sulphamates. Some sulphonamides, such as acetazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, sulthiame and 4-(2-hydroxymethyl-4-nitrophenyl-sulphonamido)ethylbenzenesulphonamide were effective CpeCA inhibitors, with K_Is in the range of 37.4-71.6 nM. Zonisamide and saccharin were the least effective such inhibitors, whereas many other aromatic and heterocyclic sulphonamides were moderate - weak inhibitors with K_Is ranging between 113 and 8755 nM. Thus, this study provides the basis for developing better clostridial enzyme inhibitors with potential as antiinfectives with a new mechanism of action.

Fulminant Hepatic Failure and Fatal Cerebral Edema Following Clostridium perfringens Bacteremia: Case Report and Review of Literature

Clostridium perfringens (CP) bacteremia is a rare but rapidly fatal infection. Only 36 cases of CP bacteremia with gas containing liver abscesses on image studies have been reported in the literature since 1990. In this report, we describe a 65-year-old diabetic male with CP bacteremia which progressed into fulminant hepatic failure with subsequent fatal cerebral edema.

Anal Canal Gas Gangrene in Aplastic Anaemia: Rare yet Lethal Entity - A Caveat

Gas gangrene is one of the most serious infections of traumatic and surgical wounds. The importance lies in the fact that, if not managed at the right time, the condition is fatal. Though perianal cellulitis and gangrene are commonly reported in immunocompromised patients, we report the case of a patient with gas gangrene involving only the anal canal extending to the rectum, a rare presentation to be reported in literature.  An 18-year-old lady, a patient of aplastic anaemia - immunodeficiency, developed gas gangrene of the anal canal possibly due to faecal contamination of anal fissures. The patient was managed with surgical debridement and intravenous antibiotics.  The clinical manifestations of gas gangrene are due to the liberation of toxins by Clostridium perfringens. The infection spreads rapidly and results in necrosis and devitalisation of tissues, unless intervened surgically. The clinical manifestations are more rapid and a high index of suspicion is needed for the diagnosis.

Clostridium perfringens: a rare cause of spondylodiscitis case report and review of the literature

Presented is a case of a 64-year old male with a unique and yet unreported case of a spondylodiscitis caused by Clostridium perfringens. Becoming symptomatic with massive neurological deficits. Computed tomography (CT) revealed typical signs of spondylodiscitis involving the vertebral body L5 with extensive vacuum phenomenon.

Single molecule compression reveals intra-protein forces drive cytotoxin pore formation

Perfringolysin O (PFO) is a prototypical member of a large family of pore-forming proteins that undergo a significant reduction in height during the transition from the membrane-assembled prepore to the membrane-inserted pore. Here, we show that targeted application of compressive forces can catalyze this conformational change in individual PFO complexes trapped at the prepore stage, recapitulating this critical step of the spontaneous process. The free energy landscape determined from these measurements is in good agreement with that obtained from molecular dynamics simulations showing that an equivalent internal force is generated by the interaction of the exposed hydrophobic residues with the membrane. This hydrophobic force is transmitted across the entire structure to produce a compressive stress across a distant, otherwise stable domain, catalyzing its transition from an extended to compact conformation. Single molecule compression is likely to become an important tool to investigate conformational transitions in membrane proteins.

DOI:http://dx.doi.org/10.7554/eLife.08421.001

Proteins are made up of chains of amino acids that need to fold into intricate three-dimensional shapes to work correctly. But some proteins also have to change their shape drastically when they work. Mechanical forces that change the shape of a protein can therefore be used to determine how a protein folds and how it changes its structure when working.

Although researchers have developed techniques to analyze the effect of force on single proteins, most studies carried out so far have investigated the effect of stretching (or tensile forces) to understand structural changes that naturally involve an extension within the protein. However, many proteins undergo structural changes that involve a compaction in their shape. How these changes occur remains poorly understood because, for these, methods to apply compressive forces to single proteins are required.

Perfringolysin O (PFO for short) is a protein that is made by a bacterium that causes food poisoning in humans. PFO makes pores in the membrane that surrounds cells. This causes the cell’s contents to leak out, killing the cell. When inserting into the membrane, PFO changes from an elongated “prepore” state to a compact pore-forming state.

Czajkowsky et al. now use a combination of single molecule techniques and computer simulations to investigate how PFO undergoes this compaction. Previous work had identified a mutant PFO protein that arrests at the prepore state. Applying a compressive force to the top of this prepore-trapped PFO as it sits on the membrane transmitted forces across the entire PFO protein. This ultimately produced a compressive force across a distant part of the protein that caused the protein to change from the elongated prepore state to the compact, pore-like shape. If a compressive force was not applied, the PFO protein remained in the prepore state. Czajkowsky et al. further found that this compressive force is naturally produced by distant water-repellent parts of the naturally occurring protein interacting with the cell membrane. Therefore, internal forces can transmit across proteins to drive shape changes in distant regions.

In the future, the methods developed in this study could be applied to analyze other naturally occurring changes in proteins where shape compaction happens when working.

DOI:http://dx.doi.org/10.7554/eLife.08421.002

Clostridium perfringens meningitis, Plesiomonas shigelloides sepsis: A lethal combination

Background:

Anaerobic bacterial meningitis is rare. It is extremely unusual without a portal of entry as most cases reported have been associated with trauma or neurosurgery.

Case Report:

We describe this rare case of clostridium meningitis and plesiomonas sepsis in an immunocompetent adult. A 71 year old man with diabetes presented with acute onset severe headaches, obtundation and signs of severe hemolysis following a 2 week game hunting trip in the Swiss Alps. His clinical status progressed rapidly; he died 3 hours after initial presentation. Post mortem lumbar puncture was performed with CSF analysis suggestive of bacterial meningitis. Clostridium perfringens was eventually recovered from the CSF as well as in the blood. Plesiomonas shigelloides was recovered from the blood as well.

Conclusions:

This is the first case of blood stream infection with these two organisms in a single patient without an obvious portal of entry.

The potential anti-herbivory role of microorganisms on plant thorns

Thorns, spines and prickles are some of the anti-herbivore defenses that plants have evolved. They were recently found to be commonly aposematic (warning coloration). However, the physical anti-herbivore defense executed by these sharp structures seems to be only the tip of the iceberg. We show that thorns of various plant species commonly harbor an array of aerobic and anaerobic pathogenic bacteria including Clostridium perfringens the causative agent of the life-threatening gas gangrene, Bacillus anthracis, and Pantoea agglomerans. Septic inflammation caused by plant thorn injury can result not only from bacteria. Medical literature indicates that thorns, spines or prickles also introduce pathogenic fungi into animals or humans. Dermatophytes that cause subcutaneous mycoses are unable to penetrate the skin and must be introduced into the subcutaneous tissue by a puncture wound. The common microorganism-thorn combinations seem to have been an important contributor to the fact that so many plant thorns are aposematically colored, as a case of convergent evolution of aposematism in these organisms.

Comparison between a live, attenuated anticoccidial vaccine and an anticoccidial ionophore, on performance of broilers raised with or without a growth promoter, in an initially Eimeria-free environment

An experiment was carried out to study the effects of vaccination with Paracox, a live, attenuated vaccine against avian coccidiosis, on broilers isolated from extraneous Eimeria parasites. The study involved 3200 broiler chickens raised in floor pens similar to commercial conditions, but in an initially Eimeria-free environment. Forty percent of the chickens were vaccinated at 3 days of age and given either a basal unmedicated feed or a feed supplemented with the feed antibiotic virginiamycin. Unvaccinated birds were given either the basal feed or feed supplemented either with virginiamycin or the anticoccidial ionophore narasin. At slaughter at 36 days of age vaccinated birds had a lower live weight than non-vaccinated birds. The difference was 4.6% in unmedicated, and 6.0% in virginiamycin medicated chickens. Feed conversion ratio at slaughter was 2.5% higher for unmedicated vaccinated birds, and 1.3% higher for virginiamycin medicated vaccinated birds, compared to respective non-vaccinated groups. There was no significant difference in overall performance of unvaccinated birds given narasin as compared to virginiamycin. At 10 days post vaccination vaccinated birds had a higher number of Clostridium perfringens in the caeca, but there was no difference thereafter. Throughout the experiment, caecal clostridial counts were considerably higher in vaccinated unmedicated birds than in unvaccinated birds given narasin. The number of oocysts shed in the vaccinated groups was very low, but during a subsequent challenge with E. maxima and E. tenella the birds' immunity was found to be satisfactory.