Indigenous Plasmodium falciparum malaria in Queens, NY.

Cryptic/sporadic malaria is rare in the United States. We describe a patient who developed malaria in New York City without any known contact with, or travel to, a malaria-endemic area. The patient presented with symptoms of gastroenteritis. Later, she developed hemolysis and hepatosplenomegaly, and Plasmodium falciparum was found in blood smears. Possible sources of malaria could be an indigenous infected mosquito or a transported infected mosquito from a local international airport.

Bacterial infections in HIV-infected patients.

Although the original opportunistic pathogens described in AIDS were protozoal and fungal organisms, bacterial infections are now recognized with increased prevalence and altered expression in patients with HIV infection. Especially since populations outside of North America and populations of i.v. drug abusers have been studied, bacterial infections have been shown to cause substantially increased morbidity and mortality both early and late in the course of HIV infection. Just as strategies have been developed for primary and secondary prophylaxis of classical HIV-related opportunistic infections, prevention of bacterial complications should be a high priority. Good hygiene and avoidance of unsterile needles in illicit drug use, tattooing, ear-piercing, or other cosmetic or ritual activities should be emphasized in patient education. Patients should be counseled to avoid uncooked or poorly cooked eggs and poultry and to avoid unpasteurized milk products. Pneumococcal vaccine is recommended for all HIV-seropositive patients and should be given as early as possible after recognition of HIV infection for maximal efficacy. Influenza vaccine is also recommended. It may have a role in preventing bacterial pneumonia secondary to influenza. Patient management should include regular dental care and nutritional evaluation. The use of intravenous or central catheters should be limited to essential therapies. When patients present with new febrile illness, a high index of suspicion for invasive bacterial disease is appropriate. The signs of serious bacterial infection in HIV-positive patients are subtle. Diagnostic evaluation should include cultures of blood and other relevant clinical specimens. Empiric antimicrobial therapy based on the clinical presentation may be life saving in patients with invasive bacterial disease complicating HIV infection.

Gastrointestinal histoplasmosis in HIV infection: two cases of colonic pseudocancer and review of the literature.

Primary gastrointestinal infection is an uncommon manifestation of histoplasmosis. It is almost always associated with disseminated disease and/or an immunocompromised host. The ileum and cecum are the most common sites involved. We report two cases of primary gastrointestinal histoplasmosis in HIV-seropositive men who presented with annular constricting right colon lesions.

Anaerobic mediastinitis complicating median sternotomy.

Two cases of mediastinitis and bacteremia caused by Bacteroides species following median sternotomy are described. In both patients, purulent sternal drainage and signs of systemic toxicity led to the diagnosis. Surgical reexploration and administration of appropriate antibiotics effected clinical cure. Although there is only a single previous case of anaerobic mediastinitis following median sternotomy incision reported, these two cases suggest that this unusual infection may not be so rare as previously thought.

Trypanosoma cruzi: reversal of inhibition of host muscle differentiation after exposure to elevated temperatures.

The L6E9 myoblast cell line can be grown as individual cells in "growth medium," or can be induced to fuse and differentiate to form multinucleated myotubes either at 37 C or at 40.5 C in "differentiation medium." It has previously been shown that myoblasts with infected Trypanosoma cruzi (Brazil strain) cannot differentiate to form myotubes. Moreover, the mRNAs for contractile proteins are not induced in these infected cells. Infected myoblasts grown in "differentiation medium" at 37C were unable to differentiate by 7 days. The infection was maintained at 100%, and the number of trypomastigotes in the supernatant increased with time (peak greater than 10(6)/ml). At 40.5C, however, infected myoblasts gradually eliminated their infection. The percentage of parasitized cells was reduced to less than 1% by the 7th day of observation. There was also a decrease in the number of trypomastigotes in the supernatant. Moreover, significant fusion was observed in these cultures by morphological criteria. Using 32P-labeled recombinant DNA probes, it was shown that, at 37C, there was an inhibition of mRNAs for muscle-specific contractile proteins (myosin heavy chain and alpha-actin), whereas nonspecific mRNAs were not inhibited. Furthermore, infected myoblasts exposed to 40.5C exhibited no inhibition of mRNAs for myosin heavy chain and alpha-actin. Myoblasts cleared of their infection could readily be reinfected. This study demonstrates that the inhibition of muscle differentiation induced by T. cruzi is reversible when cultures are exposed to elevated temperatures.