The role of MRSA (methicillin-resistant Staphylococcus aureus) adherence and colonization in the upper respiratory tract of geriatric patients in nosocomial pulmonary infections

Staple-assisted laryngectomy for intractable aspiration

Staple-assisted laryngectomy is a unique method previously reported by Lukyanchenko to prevent wound contamination by using a stapling device for suturing pharyngeal defects in total laryngectomy. We have modified his method and applied it to prevent a postoperative pharyngocutaneous fistula in the treatment of intractable aspiration. In contrast to laryngeal cancer patients, a combined use of an intraluminal light to guide the dissection and laryngofissure to pull the epiglottis can be used to facilitate the use of the stapling device. For most patients with intractable aspiration who have significant malnutrition and drug-resistant bacterial colonization of the pharynx, this method offers certain advantages. This report describes our successful experience with this method in the management of patients with intractable aspiration.

Clonal associations among Staphylococcus aureus isolates from various sites of infection

A molecular epidemiological analysis was undertaken to identify lineages of Staphylococcus aureus that may be disproportionately associated with infection. Pulsed-field gel electrophoresis analysis of 405 S. aureus clinical isolates collected from various infection types and geographic locations was performed. Five distinct S. aureus lineages (SALs 1, 2, 4, 5, and 6) were identified, which accounted for 19.01, 9.14, 22.72, 10.12, and 4.69% of isolates, respectively. In addition, 85 lineages which occurred with frequencies of <2.5% were identified and were termed "sporadic." The most prevalent lineage was methicillin-resistant S. aureus (SAL 4). The second most prevalent lineage, SAL 1, was also isolated at a high frequency from the anterior nares of healthy volunteers, suggesting that its prevalence among clinical isolates may be a consequence of high carriage rates in humans. Gene-specific PCR was carried out to detect genes for a number of staphylococcal virulence traits. tst and cna were found to be significantly associated with prevalent lineages compared to sporadic lineages. When specific infection sites were examined, SAL 4 was significantly associated with respiratory tract infection, while SAL 2 was enriched among blood isolates. SAL 1 and SAL 5 were clonally related to SALs shown by others to be widespread in the clinical isolate population. We conclude from this study that at least five phylogenetic lineages of S. aureus are highly prevalent and widely distributed among clinical isolates. The traits that confer on these lineages a propensity to infect may suggest novel approaches to antistaphylococcal therapy.

Molecular analysis of methicillin-resistant Staphylococcus aureus as a causative agent of bronchopulmonary infection: relation to colonization in the upper respiratory tract

Using five diagnostic markers, we compared the types of 72 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated simultaneously from the nasal cavity, pharynx, and sputum from 24 patients. Almost identical MRSA types had colonized the nasal cavity and sputum from the same patient for 21 (88%) of the patients. We speculate that most MRSA organisms isolated in sputum are derived from the nasal cavity, while a few are derived from the pharynx.

A long-term survey of methicillin-resistant Staphylococcus aureus in the oral cavity of children

Methicillin-resistant Staphylococcus aureus (MRSA), an indigenous bacteria in healthy people, often causes nosocomial infections. If the host human becomes compromised, MRSA can cause a serious infection. The long-term colonization of MRSA increases this risk. The purpose of this study was to demonstrate the incidence of S. aureus and MRSA colonization in the oral cavities of healthy children, and to examine the stability of identical strains of MRSA over a long-term period. Fourteen children were examined in two stages (first stage: 1987-88, second stage: 1992-93). Five of the 14 children were negative for S. aureus in both stages, seven children were positive in both stages and two children were positive in only the second stage. The children who were colonized with S. aureus in the first stage always harbored the bacteria in the second stage. Of the seven children that were positive for S. aureus in both stages, three persisted in carrying MRSA. We compared two MRSA strains isolated from the same children in both stages by coagulase typing, antibiogram typing and DNA fingerprinting. In two children, the strains showed the same coagulase types, similar antibiograms and similar DNA fragment profiles. These data strongly suggest that identical strains of MRSA persisted in the oral cavities for more than five years, and that the oral cavity can serve as a reservoir for MRSA with the potential to cause nosocomial infections.

Nasal carriage of Staphylococcus aureus: epidemiology, underlying mechanisms, and associated risks

Staphylococcus aureus has long been recognized as an important pathogen in human disease. Due to an increasing number of infections caused by methicillin-resistant S. aureus (MRSA) strains, therapy has become problematic. Therefore, prevention of staphylococcal infections has become more important. Carriage of S. aureus appears to play a key role in the epidemiology and pathogenesis of infection. The ecological niches of S. aureus are the anterior nares. In healthy subjects, over time, three patterns of carriage can be distinguished: about 20% of people are persistent carriers, 60% are intermittent carriers, and approximately 20% almost never carry S. aureus. The molecular basis of the carrier state remains to be elucidated. In patients who repeatedly puncture the skin (e.g., hemodialysis or continuous ambulatory peritoneal dialysis [CAPD] patients and intravenous drug addicts) and patients with human immunodeficiency virus (HIV) infection, increased carriage rates are found. Carriage has been identified as an important risk factor for infection in patients undergoing surgery, those on hemodialysis or CAPD, those with HIV infection and AIDS, those with intravascular devices, and those colonized with MRSA. Elimination of carriage has been found to reduce the infection rates in surgical patients and those on hemodialysis and CAPD. Elimination of carriage appears to be an attractive preventive strategy in patients at risk. Further studies are needed to optimize this strategy and to define the groups at risk.

Moraxella (Branhamella) catarrhalis adherence to human bronchial and oropharyngeal cells: the role of adherence in lower respiratory tract infections

To study the role of Moraxella (subgenus Branhamella) catarrhalis (B. catarrhalis) adherence to airway cells in lower respiratory tract infections, the in vitro attachments of B. catarrhalis to upper airway (oropharyngeal) and lower airway (bronchial) epithelial cells were compared. The adherence of 4 strains (1 nonfimbriated and 3 fimbriated) of B. catarrhalis to respiratory tract epithelial cells collected from 11 patients with chronic pulmonary disease (CPD) and 11 healthy individuals was evaluated. Both the fimbriated and nonfimbriated strains showed increased attachment to oropharyngeal cells in the CPD patients (mean +/- SEM; 25.0 +/- 3.2/cell; P < 0.01) when compared to the control subjects (12.1 +/- 1.1/cell). On the average, the attachment to bronchial cells was 6.1 to 13.6 times greater per surface area (bacteria/micron2) than the attachment to oropharyngeal cells. The fimbriated strains tended to adhere in higher numbers to bronchial cells (19.0 +/- 1.8/cell) than the nonfimbriated strain (8.7 +/- 1.2/cell), although there was no difference between the CPD and control groups. In conclusion, the attachment of B. catarrhalis to oropharyngeal cells may be an enhancing factor for colonization in the upper respiratory tract in patients with CPD, and elevated adherence of the bacteria to bronchial cells may suggest pathogenic importance when mucociliary function is impaired.