Publications

Pseudomonas aeruginosa is an opportunistic pathogen that can, like other bacterial species, exist in antimicrobial resistant sessile biofilms and as free-swimming, planktonic cells. Specific virulence factors are typically associated with each lifestyle and several two component response regulators have been shown to reciprocally regulate transition between biofilm-associated chronic, and free-swimming acute infections. Quorum sensing (QS) signal molecules belonging to the las and rhl systems are known to regulate virulence gene expression by P. aeruginosa. However the impact of a recently described family of novel quorum sensing signals produced by the Pseudomonas Quinolone Signal (PQS) biosynthetic pathway, on the transition between these modes of infection is less clear. Using clonal isolates from a patient developing ventilator-associated pneumonia, we demonstrated that clinical observations were mirrored by an in vitro temporal shift in isolate phenotype from a non-secreting, to a Type III cytotoxin secreting (TTSS) phenotype and further, that this phenotypic change was PQS-dependent. While intracellular type III cytotoxin levels were unaffected by PQS concentration, cytotoxin secretion was dependent on this signal molecule. Elevated PQS concentrations were associated with inhibition of cytotoxin secretion coincident with expression of virulence factors such as elastase and pyoverdin. In contrast, low concentrations or the inability to biosynthesize PQS resulted in a reversal of this phenotype. These data suggest that expression of specific P. aeruginosa virulence factors appears to be reciprocally regulated and that an additional level of PQS-dependent post-translational control, specifically governing type III cytotoxin secretion, exists in this species.

BACKGROUND

Although three quarters of reproductive-age women see a health provider annually, less than half receive recommended contraceptive counseling services. We sought to explore providers' perspectives on the challenges to contraceptive counseling in primary care clinics to develop strategies to improve counseling services.

METHODS

A qualitative, focus group (n = 8) study was conducted in November and December 2007; 48 of 90 providers practicing in four primary care clinics at the University of Pittsburgh Medical Center participated. Providers included physicians, nurses, and pharmacists working in these clinics' multidisciplinary teams. Discussions explored perceived barriers to the provision of counseling services. All groups were audiorecorded, transcribed, and entered into Atlas.Ti, a qualitative data management software. The data were analyzed using a grounded theory approach to content analysis.

RESULTS

Perceived patient, provider, and health system barriers to contraceptive counseling were identified. Perceived patient barriers included infrequent sexual activity, familiarity with a limited number of methods, desire for pregnancy despite medical contraindications, and religious beliefs. Provider barriers included lack of knowledge, training, and comfort; assumptions about patient pregnancy risk; negative beliefs about contraceptive methods; reliance on patients to initiate discussions; and limited communication between primary care providers (PCPs) and subspecialists. Health system barriers included limited time and competing medical priorities.

CONCLUSIONS

PCPs vary widely in their knowledge, perceived competence, and comfort in providing contraceptive counseling. General efforts to improve integration of contraceptive counseling into primary care services in addition to electronic reminders and efficient delivery of contraceptive information are needed.