Staphylococcal infections in hospitals. Recent developments in epidemiologic and laboratory investigation

Infection control through the ages

To appreciate the current advances in the field of health care epidemiology, it is important to understand the history of hospital infection control. Available historical sources were reviewed for 4 different historical time periods: medieval, early modern, progressive, and post-World War II. Hospital settings for the time periods are described, with particular emphasis on the conditions related to hospital infections.

Effects of Helicobacter hepaticus on the proteome of HEp-2 cells

Helicobacter hepaticus infects the bowel and biliary tree of several animals, producing inflammation. Colonisation of mouse livers can induce hepatocellular carcinomas. The effects of H. hepaticus on the proliferation and global protein expression of human HEp-2 cells were studied by examining the changes in the protein profiles of cells exposed to the bacterium. HEp-2 cells were grown for four days under a microaerobic atmosphere or under the same conditions in co-cultures with H. hepaticus at various inoculum densities. Enlargement, distension and elongation of HEp-2 cells were observed in co-cultures with H. hepaticus. The number of live cells declined by only an order of magnitude at bacterial inocula of approximately 10(9)cfu/ml, but were reduced to less than 10(3)cells/ml at approximately 10(10)cfu/ml bacteria inocula. Protein expression by HEp-2 cells was investigated employing two-dimensional gel electrophoresis. In cells grown with or without bacteria, 17 differentially expressed proteins were identified by tandem mass spectrometry. These proteins participated in several biological functions including amino acid metabolism, cell growth and proliferation, stress response, protein translation and modification, etc. The onset of a catastrophic killing of HEp-2 cells at a bacterial density of approximately 10(9)cfu/ml suggested a multimodal action for H. hepaticus infection, and the modulation of the expression of proteins involved in different biological functions showed that the presence of H. hepaticus has broad effects on the physiology of HEp-2 cells.

Identification of enolase as a laminin-binding protein on the surface of Staphylococcus aureus

We have previously demonstrated that Staphylococcus aureus, a highly invasive bacteria, presents a 52-kDa surface protein that mediates its binding to laminin. In order to better characterize this receptor, we excised this putative laminin receptor from two-dimensional (2-D) PAGE and used it as antigen for raising a mouse hyperimmune serum which was for screening an S. aureus expression library. A single clone of 0.3 kb was obtained, and its sequence revealed 100% homology with S. aureus alpha-enolase. Moreover, amino acid sequencing of the 52-kDa protein eluted from the 2-D gel indicated its molecular homology with alpha-enolase, an enzyme that presents a high evolutionary conservation among species. In parallel, monoclonal antibodies raised against the S. aureus 52-kDa band also recognized yeast alpha-enolase in western blot analysis. These monoclonal antibodies were also able to promote capture of iodine-labeled bacteria when adsorbed to a solid phase, and this capture was inhibited by the addition of excess rabbit muscle alpha-enolase. Finally, the cell surface localization of S. aureus alpha-enolase was further confirmed by flow cytometry. Hence, alpha-enolase might play a critical role in the pathogenesis of S. aureus by allowing its adherence to laminin-containing extracellular matrix.

The hospital's obligation to protect patients from carriers of infectious diseases

Nosocomial infection is a serious problem in hospitals and other inpatient health care facilities. It has been receiving increasing attention in the medical literature since the first outbreaks of penicillin-resistant staphylococcal infections were recognized in the 1950s. The medical profession has been forced to acknowledge, albeit reluctantly, that infectious diseases are not going to be eradicated by the administration of antibiotics and antimicrobials alone. Microogranisms have shown amazing resilience in their ability to protect themselves against the most sophisticated drugs in our armamentarium by the formation of resistant strains. Further, organisms which were never believed to cause disease in the pre-antibiotic era are now linked with devastating infections in seriously ill hospitalized patients. Even the organisms commonly found on the skin of a healthy person can cause disease given the right set of circumstances. A carrier, however, is a person who harbors a specific pathogenic organism, yet fails to exhibit any discernible symptom of the disease. Nonetheless, the carrier is capable of spreading the organism to others.

Septic endarteritis due to intra-arterial catheters for cancer chemotherapy. I. Evaluation of an outbreak. II. Risk factors, clinical features and management, III. Guidelines for prevention

A cluster of three cases of staphylococcal septic endarteritis originating from percutaneously inserted brachial artery catheters for regional cancer chemotherapy prompted an epidemiologic and clinical study of bacteremic infections associated with this therapeutic modality. Nine cases were identified over a 3 1/2-year period (1.6% of all catheterizations), all caused by Staphylococcus aureus. The cluster followed discontinuation of hexachlorophene for scrub of the extremity prior to cannulation; phage-typing suggested the three cases were caused by the patients' own strains of Staphylococcus. These infections produced a distinctive clinical syndrome which facilitates implicating the catheter in the genesis of fever occurring in a patient receiving intra-arterial chemotherapy: early localized pain (89%) and hemorrhage (78%), and Osler's nodes distally (44%), later followed by local inflammation (78%), purulence (56%) and signs of systemic sepsis (100%) (each factor, p less than or equal to .005). Duration of cannulation did not influence susceptibility to infection. However, difficult cannulations or need for repositioning the catheter (p = .0096), prior radiation therapy (p = .033), leukopenia (p less than .05) and hypoalbuminemia (p less than .05) were all associated with septicemia. In the 25 months since implementation of specific control measures, there have been no further catheter-related septicemia in 310 catheterization (p less than .001). Guide-lines for prevention and management of these infections are provided.

Antibiotic susceptibilities of 120 strains of Staphylococcus aureus isolated from patients at a Children's Hospital. Decline of hospital staphylococci as compared with staphylococci in outpatients. A reversal

The antibiotic sensitivities of 120 strains of Staphylococcus aureus isolated from both hospitalized patients and outpatients at Children's Memorial Hospital, Oklahoma City were studied. The proportions of strains resistant to the commonly used antibiotics were considerably lower than that found by other workers in earlier years, except for penicillin G. Of the 120 strains, 98 (81.7%) were resistant to penicillin G, 13 (10.8%) to tetracycline, 9 (7.5%) to erythromycin, and 3 (2.5%) to clindamycin. No strains resistant against cephalothin, chloramphenicol, gentamicin, or oxacillin were found. Sixteen strains (13.3%), of which 5 were inpatient strains and 11 were outpatient strains, were found to be resistant to more than one drug. Phage group 1 or type 80/81 staphylococci were not found among multiple resistant strains from hospitalized patients.