Bacillus cereus endogenous panophthalmitis

Bacillus cereus panophthalmitis with delayed dermis fat graft

Bacillus cereus panophthalmitis secondary to intravenous drug use typically leads to an explosive ocular and/or orbital infection. Though several cases of B. cereus panophthalmitis secondary to intravenous drug use have been reported, no clear consensus exists regarding preferred surgical technique and orbital reconstruction. Additionally, no cases describe delayed dermis fat graft placement following enucleation for such cases. Herein, a case of B. cereus panophthalmitis secondary to intravenous methamphetamine use is presented, where delayed dermis fat graft placement following enucleation and orbital washout provided an excellent functional and cosmetic outcome.

The cereus matter of Bacillus endophthalmitis

Bacillus cereus (B. cereus) endophthalmitis is a devastating intraocular infection primarily associated with post-traumatic injuries. The majority of these infections result in substantial vision loss, if not loss of the eye itself, within 12-48 h. Multifactorial mechanisms that lead to the innate intraocular inflammatory response during this disease include the combination of robust bacterial replication, migration of the organism throughout the eye, and toxin production by the organism. Therefore, the window of therapeutic intervention in B. cereus endophthalmitis is quite narrow compared to that of other pathogens which cause this disease. Understanding the interaction of bacterial and host factors is critical in understanding the disease and formulating more rational therapeutics for salvaging vision. In this review, we will discuss clinical and research findings related to B. cereus endophthalmitis in terms of the organism's virulence and inflammogenic potential, and strategies for improving of current therapeutic regimens for this blinding disease.

CXCL1, but not IL-6, significantly impacts intraocular inflammation during infection

During intraocular bacterial infections, the primary innate responders are neutrophils, which may cause bystander damage to the retina or perturb the clarity of the visual axis. We hypothesized that cytokine IL-6 and chemokine CXCL1 contributed to rapid neutrophil recruitment during Bacillus cereus endophthalmitis, a severe form of intraocular infection that is characterized by explosive inflammation and retinal damage that often leads to rapid vision loss. To test this hypothesis, we compared endophthalmitis pathogenesis in C57BL/6J, IL-6^-/-, and CXCL1^-/- mice. Bacterial growth in eyes of CXCL1^-/-, IL-6^-/-, and C67BL/6J mice was similar. Retinal function retention was greater in eyes of IL-6^-/- and CXCL1^-/- mice compared with that of C57BL/6J, despite these eyes having similar bacterial burdens. Neutrophil influx into eyes of CXCL1^-/- mice was reduced to a greater degree compared with that of eyes of IL6^-/- mice. Histology confirmed significantly less inflammation in eyes of CXCL1^-/- mice, but similar degrees of inflammation in IL6^-/- and C57BL/6J eyes. Because inflammation was reduced in eyes of infected CXCL1^-/- mice, we tested the efficacy of anti-CXCL1 in B. cereus endophthalmitis. Retinal function was retained to a greater degree and there was less overall inflammation in eyes treated with anti-CXCL1, which suggested that anti-CXCL1 may have therapeutic efficacy in limiting inflammation during B. cereus endophthalmitis. Taken together, our results indicate that absence of IL-6 did not affect overall pathogenesis of endophthalmitis. In contrast, absence of CXCL1, in CXCL1^-/- mice or after anti-CXCL1 treatment, led to an improved clinical outcome. Our findings suggest a potential benefit in targeting CXCL1 to control inflammation during B. cereus and perhaps other types of intraocular infections.

Bacillus cereus, a volatile human pathogen

Bacillus cereus is a Gram-positive aerobic or facultatively anaerobic, motile, spore-forming, rod-shaped bacterium that is widely distributed environmentally. While B. cereus is associated mainly with food poisoning, it is being increasingly reported to be a cause of serious and potentially fatal non-gastrointestinal-tract infections. The pathogenicity of B. cereus, whether intestinal or nonintestinal, is intimately associated with the production of tissue-destructive exoenzymes. Among these secreted toxins are four hemolysins, three distinct phospholipases, an emesis-inducing toxin, and proteases. The major hurdle in evaluating B. cereus when isolated from a clinical specimen is overcoming its stigma as an insignificant contaminant. Outside its notoriety in association with food poisoning and severe eye infections, this bacterium has been incriminated in a multitude of other clinical conditions such as anthrax-like progressive pneumonia, fulminant sepsis, and devastating central nervous system infections, particularly in immunosuppressed individuals, intravenous drug abusers, and neonates. Its role in nosocomial acquired bacteremia and wound infections in postsurgical patients has also been well defined, especially when intravascular devices such as catheters are inserted. Primary cutaneous infections mimicking clostridial gas gangrene induced subsequent to trauma have also been well documented. B. cereus produces a potent beta-lactamase conferring marked resistance to beta-lactam antibiotics. Antimicrobials noted to be effective in the empirical management of a B. cereus infection while awaiting antimicrobial susceptibility results for the isolate include ciprofloxacin and vancomycin.

Nosocomial bacteremia and catheter infection by Bacillus cereus in an immunocompetent patient

We present a case of Bacillus cereus bacteremia and catheter infection in an immunocompetent patient subjected to abdominal surgery, who recovered following central catheter removal and treatment with piperacillin/tazobactam.

Ocular manifestations of injection drug use

Injection drug use can result in a variety of severe ocular conditions. Hematogenous dissemination of various fungi and bacteria may produce endophthalmitis with resultant severe visual loss. Retinal arterial occlusive disease may result from talc and other particulate emboli. Most commonly, life-threatening systemic diseases such as endocarditis and HIV infection secondarily affect the eye. Because many of these conditions may result in blindness if untreated, accurate diagnosis and prompt initiation of therapy are essential.

Endophthalmitis

Endophthalmitis is an inflammatory reaction of intraocular fluids or tissues. Infectious endophthalmitis is one of the most serious complications of ophthalmic surgery. Occasionally, infectious endophthalmitis is the presenting feature of an underlying systemic infection. Successful management of infectious endophthalmitis depends on timely diagnosis and institution of appropriate therapy. Recognition of the different clinical settings in which endophthalmitis occurs and awareness of the highly variable presentation it may have facilitate timely diagnosis. Biopsy of intraocular fluid/tissue is the only method that permits reliable diagnosis and treatment. The different presenting clinical settings, a rational approach to diagnosis (i.e., when, what, and how to biopsy), and the treatment of infectious endophthalmitis are reviewed.

Bacillus cereus and related species

Bacillus cereus is a gram-positive aerobic or facultatively anaerobic spore-forming rod. It is a cause of food poisoning, which is frequently associated with the consumption of rice-based dishes. The organism produces an emetic or diarrheal syndrome induced by an emetic toxin and enterotoxin, respectively. Other toxins are produced during growth, including phospholipases, proteases, and hemolysins, one of which, cereolysin, is a thiol-activated hemolysin. These toxins may contribute to the pathogenicity of B. cereus in nongastrointestinal disease. B. cereus isolated from clinical material other than feces or vomitus was commonly dismissed as a contaminant, but increasingly it is being recognized as a species with pathogenic potential. It is now recognized as an infrequent cause of serious nongastrointestinal infection, particularly in drug addicts, the immunosuppressed, neonates, and postsurgical patients, especially when prosthetic implants such as ventricular shunts are inserted. Ocular infections are the commonest types of severe infection, including endophthalmitis, panophthalmitis, and keratitis, usually with the characteristic formation of corneal ring abscesses. Even with prompt surgical and antimicrobial agent treatment, enucleation of the eye and blindness are common sequelae. Septicemia, meningitis, endocarditis, osteomyelitis, and surgical and traumatic wound infections are other manifestations of severe disease. B. cereus produces beta-lactamases, unlike Bacillus anthracis, and so is resistant to beta-lactam antibiotics; it is usually susceptible to treatment with clindamycin, vancomycin, gentamicin, chloramphenicol, and erythromycin. Simultaneous therapy via multiple routes may be required.

In vitro susceptibilities of ocular Bacillus cereus isolates to clindamycin, gentamicin, and vancomycin alone or in combination

A broth dilution assay was used to determine the in vitro susceptibilities of 10 ocular isolates of Bacillus cereus to clindamycin, gentamicin, and vancomycin both alone and in combination. The checkerboard technique was used to determine fractional inhibitory and bactericidal concentration indices for combinations of clindamycin-gentamicin and vancomycin-gentamicin.

Antibiotic therapy for Bacillus species infections

We reviewed 36 cases of culture-proven Bacillus species ocular infections occurring between September 1974 and December 1989. Kirby-Bauer disk sensitivities were available in 34 of the 36 cases (95%). All Bacillus species isolates were sensitive to the aminoglycoside antibiotics (N = 34) and to vancomycin hydrochloride (N = 32); resistance to clindamycin was found in four of 18 (22%) of tested isolates. Although B. cereus was uniformly sensitive to these antibiotics, resistance to clindamycin occurred in four cases in the non-B. cereus group. The microbroth dilution technique confirmed the Kirby-Bauer data. The aminoglycosides were uniformly effective, but the cephalosporins (first, second, and third generation drugs) were consistently ineffective against B. cereus and varied from sensitive to moderately sensitive for the non-B. cereus isolates. Our microbiologic laboratory findings suggest that vancomycin hydrochloride in combination with an aminoglycoside ensures more consistent antibiotic coverage of Bacillus species ocular infections.

Bacillus-induced endophthalmitis: new series of 10 cases and review of the literature

We reviewed the charts of 10 patients who were admitted to the Massachusetts Eye and Ear Infirmary over a 10-year period with the diagnosis of Bacillus species endophthalmitis. To our knowledge this is the largest single series in the literature and includes the first two reported cases of Bacillus endophthalmitis following glaucoma filtering procedures. Seven cases developed following penetrating ocular trauma. One occurred in an intravenous drug abuser. Five eyes ultimately underwent enucleation; only the two eyes that developed endophthalmitis after elective surgery retained useful vision. Review of the literature indicates that parenteral and intravitreal antibiotic prophylaxis against endophthalmitis after penetrating ocular trauma should include gentamicin, in combination with vancomycin or clindamycin, to provide adequate coverage against infection with Bacillus spp., as prognosis is poor once infection is established. Bacillus spp. cultured from ocular tissues or fluids should not be dismissed as contaminants.

A Bacillus cereus cytolytic determinant, cereolysin AB, which comprises the phospholipase C and sphingomyelinase genes: nucleotide sequence and genetic linkage

A cloned cytolytic determinant from the genome of Bacillus cereus GP-4 has been characterized at the molecular level. Nucleotide sequence determination revealed the presence of two open reading frames. Both open reading frames were found by deletion and complementation analysis to be necessary for expression of the hemolytic phenotype by Bacillus subtilis and Escherichia coli hosts. The 5' open reading frame was found to be nearly identical to a recently reported phospholipase C gene derived from a mutant B. cereus strain which overexpresses the respective protein, and it conferred a lecithinase-positive phenotype to the B. subtilis host. The 3' open reading frame encoded a sphingomyelinase. The two tandemly encoded activities, phospholipase C and sphingomyelinase, constitute a biologically functional cytolytic determinant of B. cereus termed cereolysin AB.

Bacillus species

The genus Bacillus is a diverse group of gram-positive, spore-forming aerobic bacilli. B anthracis, the agent of anthrax, is primarily an animal pathogen but is capable of causing human infection, most commonly of the skin or lungs. B cereus, a well-recognized cause of gastroenteritis, may occasionally cause epidemics in health institutions. Both B cereus and other Bacillus species are increasingly recognized as opportunistic pathogens in the hospitalized patient. This report is intended as a comprehensive review of the bacteriology, clinical features, and therapy of Bacillus spp infections. Nosocomial epidemics and transmission will be highlighted.

Metastatic bacterial endophthalmitis: a contemporary reappraisal

Metastatic bacterial endophthalmitis remains a challenge to the clinician despite the success of antibiotics in reducing its frequency and severity. Controversy currently surrounds the management of this condition because of uncertainty about the value of and indications for vitreous surgery. We review 72 cases of metastatic endophthalmitis from the past decade, including five not previously published. The spectrum of causative bacteria changed significantly during this period, with displacement of meningococcus by Bacillus cereus as the most frequently reported agent and an increasing incidence of infection by organisms of low pathogenicity in immunologically compromised hosts. We propose a new classification scheme for metastatic endophthalmitis based on the location (anterior or posterior segment) and extent (focal or diffuse) of the primary intraocular infection. Focal and anterior cases appear to have a good prognosis, while posterior diffuse disease nearly always leads to blindness. Our analysis of outcomes suggests that systemic antibiotics are more valuable in metastatic than in postoperative or traumatic endophthalmitis and that intraocular antibiotic injection and vitrectomy make only a limited contribution to successful treatment in metastatic infection. We recommend a clinical approach to metastatic endophthalmitis that minimizes exposure of patients to the risks of invasive procedures.

Fulminating panophthalmitis due to exogenous infection with Bacillus cereus: report of 4 cases

Bacillus cereus is a seldom recognised but important cause of panophthalmitis. Although most reported cases have been the result of endogenous infection, we have recently seen 4 cases that followed ocular trauma. In each instance a fulminating panophthalmitis developed, accompanied by fever and leucocytosis. Despite prompt therapy all eyes were rapidly lost. In view of the selective antibiotic sensitivities of this organism and the fulminating course of the disease, conventional approaches to therapy, including standard prophylactic antibiotic regimens, are unlikely to be successful in such cases. Analysis of our cases suggest that ocular infection with B. cereus has certain features that may allow a provisional diagnosis to be made before isolation of the organism. Early recognition and prompt institution of effective therapy may lead to salvage of these eyes in the feature.

The problem of bacillus species infection with special emphasis on the virulence of Bacillus cereus

Although Bacillus cereus is an uncommon ocular pathogen, infection with it usually results in loss of the eye. Although previous reports have emphasized endogenous infection, our recent experience indicates the importance of B cereus infection following trauma. Management is hampered by ineffectiveness of current empirical antibiotic regimens. This microorganism is resistant to both the penicillins and the cephalosporins. Although B cereus is susceptible to gentamicin, our studies indicate that gentamicin by itself is inadequate to eradicate the infection. B cereus, however, is susceptible to clindamycin and combined therapy with gentamicin and clindamycin appears to offer the best approach. Early diagnosis is the key to successful treatment. We believe the clinical circumstances likely to lead to B cereus infection, as well as the manifestations of the disease itself, are sufficiently distinctive to alert the ophthalmologist to the possibility of this infection. Prompt recognition of the infection should allow institution of appropriate therapy before permanent structural changes occur.