Takashi Shinha

Bacteremia due to Elizabethkingia meningoseptica

Elizabethkingia meningoseptica is a nonfermentative gram-negative bacillus that is ubiquitously found in hospital environments and as such, it has been associated with various nosocomial infections. Immunocompromised individuals are particularly at increased risk for developing severe infections due to E. meningoseptica, including bacteremia. E. meningoseptica is resistant to multiple antimicrobials commonly used for gram-negative bacteria and conventional empirical antimicrobials targeting those organisms may result in unfavorable outcome. We report a case of bacteremia due to E. meningoseptica in a patient who necessitated chronic hemodialysis therapy to heighten awareness of this emerging pathogen among patients on hemodialysis.

Hydrofiber Dressing Saturated With Mafenide Acetate Extends the Duration of Antimicrobial Activity.

Mafenide acetate is used in some burn wounds for its ability to penetrate eschar but requires frequent uncomfortable dressing changes for its application. The authors hypothesize that hydrofiber dressings will hold mafenide acetate solution for an extended period of time and maintain antimicrobial activity longer than traditional gauze, thus possibly obviating the need for frequent dressing changes. Four experimental arms included: 1) hydrofiber, stored on a dry well plate as control, 2) gauze saturated with 2.5% mafenide acetate, stored on nonsterile porcine skin, 3) hydrofiber saturated with mafenide acetate, stored on dry well plate, and 4) hydrofiber saturated with mafenide acetate, stored on nonsterile porcine skin. At 0, 24, 48, and 72 hours, a 1-cm disk was cut from the dressing sheet of each study arm, placed on agar plates seeded with Staphylococcus aureus and Pseudomonas aeruginosa, and incubated for 24 hours, and the zone of inhibition was measured. A zone of 2 mm or greater was indicative of susceptibility. Each arm of the experiment was performed four times to demonstrate reproducibility. Plain hydrofiber (control) demonstrated no zone of inhibition at any time point, thereby possessing no antimicrobial activity alone. Gauze saturated with mafenide acetate did not reliably demonstrate antimicrobial activity beyond 0 hours. Hydrofiber saturated with mafenide acetate, whether stored on a dry well plate or nonsterile porcine skin, consistently possessed sustained antimicrobial activity as demonstrated by zones of inhibition greater than 2 mm to both S. aureus and P. aeruginosa. Mafenide acetate-soaked hydrofiber dressings stay moist and maintain antimicrobial activity against S. aureus and P. aeruginosa for at least 72 hours without repeated soaks.

Endocarditis due to Gemella morbillorum

A 37-year-old man with a history of intravenous drug abuse presented with a 1-month history of a fever, chills and fatigue. The presence of a systolic ejection murmur was observed at the apex on a cardiac examination. Transesophageal echocardiography revealed a vegetation measuring 12 mm × 10 mm on the aortic valve. Multiple blood cultures turned positive; Gram staining revealed what appeared to be a Gram-negative coccus (Picture). Gemella species are Gram-positive cocci and were previously considered to be viridans streptococci. Gemella spp. are commonly found as normal residents of the oral and gastrointestinal tracts, and they tend to cause endocarditis among patients with valvular diseases (1). Gemella spp. tend to decolorize easily on Gram staining due to their relatively thin cell walls; therefore, they may appear Gram-negative. The definitive identification of Gemella spp. is of clinical importance, since the treatment of endocarditis due to Gemella spp. requires a more intense and prolonged course of antibiotic therapy than usual. It normally requires the same treatment regimen as Enterococcus species (2).

Necrotizing retinitis due to syphilis in a patient with AIDS

The ocular manifestations of syphilis are varied. Ocular syphilis can occur during any stage of infection and involve virtually any part of the eye. In immunocompetent individuals, the most common etiologies include syphilitic uveitis. Although the clinical presentation of ocular syphilis in HIV-infected patients is also widespread, posterior segment involvement has been more commonly described particularly in patients with AIDS. The diagnosis of syphilitic retinitis is challenging since its clinical presentation mimics retinitis caused by other viral etiologies. In addition, HIV-infected individuals with syphilis are more likely to develop aberrant serologic responses. Recognition of syphilitic retinitis and prompt initiation of penicillin therapy is of critical importance since syphilitic retinitis generally responds well to treatment and loss of vision is reversible. In this report, we describe a 39-year-old female with advanced stages of AIDS who developed necrotizing retinitis due to syphilis. Prompt initiation of intravenous penicillin led to excellent visual outcome for this patient despite significantly decreased visual acuity on presentation.

Intracellular Pathogens within Alveolar Macrophages in a Patient with HIV Infection: Diagnostic Challenge.

In HIV-infected individuals, macrophages, the key defense effector cells, manifest defective activity in their interactions with a wide variety of opportunistic pathogens, including fungi and protozoa. Understanding the morphological characteristics of intracellular opportunistic pathogens in addition to their pathogenesis is of critical importance to provide optimal therapy, thereby decreasing morbidity and mortality in HIV-infected patients. We herein present a case of disseminated histoplasmosis confused with disseminated visceral leishmaniasis in an HIV-infected individual from Guyana who developed intracellular organisms within alveolar macrophages.

Osteomyelitis caused by Achromobacter xylosoxidans

Achromobacter xylosoxidans is an aerobic, nonfermenting gram-negative rod and described as a waterborne bacterium since it habits aquatic environments ubiquitously. It has frequently been isolated from aquatic surroundings in the hospital and from various human body sites. Although occasionally considered a non-pathogen, A. xylosoxidans has been associated with outbreaks of nosocomial infection due to contaminated fluids. Moreover, a wide variety of infectious etiologies due to A. xylosoxidans has been reported primarily in immunocompromised individuals. Heightened awareness of this bacterium and associated clinical importance is warranted for clinicians since its broad disease spectrum in humans and frequent multi-drug resistance may result in an increased mortality rate. In this report, we describe a case of osteomyelitis caused by A. xylosoxidans in a patient with a history of diabetes mellitus.

Ramsay Hunt syndrome and zoster laryngitis with multiple cranial nerve involvement

Abstract Ramsay Hunt syndrome is characterized by varicella zoster virus infection affecting the geniculate ganglion of the facial nerve. It typically presents with vesicles in the external auditory canal associated with auricular pain and peripheral facial nerve paralysis. Although vestibulocochlear nerve is frequently co-involved during the course of Ramsay Hunt syndrome, multiple lower cranial nerve involvement has rarely been described in the literature. In addition, laryngitis due to varicella zoster virus is a diagnostic challenge due to its unfamiliarity among clinicians. We report a case of Ramsay Hunt syndrome with laryngitis involving multiple lower cranial nerves.

The Effective Duration of Antimicrobial Activity of Mafenide Acetate After Reconstitution

Mafenide acetate is an effective but costly antimicrobial solution used for burn wounds. The package insert instructs the user to discard unused solution within 48 hours of opening. The purpose of this study is to evaluate the antimicrobial activity of mafenide acetate beyond 48 hours after reconstitution, to possibly reduce cost by eliminating product waste. Staphylococcus aureus and Pseudomonas aeruginosa isolates were used to seed Mueller-Hinton agar plates. Filter paper disks were then saturated with 5% mafenide acetate at 0, 2, 7, 14, 30, and 60 days after reconstitution. Disks were then placed on the seeded agar plates and incubated. After incubation, the zone of inhibition around each plate was measured. A zone of inhibition of 2 mm or greater was indicative of susceptibility. Mafenide acetate remained efficacious, with a zone of inhibition of >2 mm to both organisms at 0, 2, 7, 14, 30, and 60 days after mafenide acetate reconstitution. This in vitro study demonstrates that the antimicrobial activity of mafenide acetate remains present for at least 60 days after reconstitution. Unused mafenide may not need to be discarded at 48 hours after opening. Reducing wasted product has the potential to translate into cost savings.

Cellulitis and Bacteremia due to Neisseria weaveri following a dog bite

Neisseria weaveri is a gram-negative rod that can cause skin and soft tissue infections associated with dog bites. Although N. weaveri is a less well recognized zoonotic Neisseria species, its potential pathogenicity merits recognition since N. weaveri can cause severe septicemia in humans.

Pericarditis due to Neisseria meningitidis serogroup W135

Neisseria meningitidis is a well-recognized cause of bacterial meningitis. Although less common, N. meningitidis can also involve extra-meningeal sites, including the pericardium. The frequency of such extra-meningeal clinical manifestations differs depending on N. meningitidis serogroup. N. meningitidis serogroups C and W135 have been reportedly associated with extra-meningeal meningococcal disease more frequently including pericarditis. In general, meningococcal pericarditis is categorized into three etiologies; primary meningococcal disease, secondary disease due to disseminated meningococcemia, and reactive form as an immunologic complication. Importantly, meningococcal pericarditis can cause massive pericardial effusion with cardiac tamponade that can lead to cardiogenic shock. We report a case of pericarditis due to N. meningitidis serogroup W135 secondary to disseminated meningococcal disease.