Acute respiratory tract infection: a practice examines its antibiotic prescribing habits.

PURPOSE: We wanted to better understand our practice behaviors by measuring antibiotic prescribing patterns for acute respiratory tract infections (ARTIs), which would perhaps help us delineate goals for quality improvement interventions. We determined (1) the distribution of ARTI final diagnoses in our practice, (2) the frequency and types of antibiotics prescribed, and (3) the factors associated with antibiotic prescribing for patients with ARTI. METHODS: We looked at office visits for adults with ARTI symptoms that occurred between December 14, 2009, and March 4, 2010. We compiled a convenience sample of 438 patient visits, collecting historical information, physical examination findings, diagnostic impressions, and treatment decisions. RESULTS: Among the 438 patients, cough was the most common presenting complaint (58%). Acute sinusitis was the most frequently assigned final diagnosis (32%), followed by viral upper respiratory tract infection (29%), and acute bronchitis (24%). Sixty-nine percent of all ARTI patients (304/438) received antibiotic prescriptions, with macrolides being most commonly prescribed (167/304 [55%]). Prescribing antibiotics was associated with a complaint of sinus pain or shortness of breath, duration of illness ≥8 days, and specific abnormal physical exam findings. Prescribing rates did not vary based on patient age or presence of risk factors associated with complication. Variations in prescribing rates were noted between individual providers and groups of providers. CONCLUSIONS: We found that we prescribed antibiotics at high rates. Diagnoses of acute sinusitis and bronchitis may have been overused as false justification for antibiotic therapy. We used broad-spectrum antibiotics frequently. We have identified several gaps between current and desired performance to address in practice-based quality improvement interventions.

Responses to the purr call in three areas of the guinea pig auditory cortex.

Single electrodes were used to record from anaesthetized animals stimulated with a closed sound system. Neural responses to the purr call were very different in the dorsocaudal core field and in two long-latency belt areas, the ventrorostral belt and the dorsocaudal belt. Responses in the dorsocaudal core field were accurately timed to the start of the nine rhythmic pulses within the purr while the ventrorostral belt responses were more sustained and less temporally precise and most dorsocaudal belt units did not respond. These results are consistent with the separate processing of narrow-band tonal stimuli such as the purr by a ventrorostral pathway involving the primary auditory area and the ventrorostral belt but not by a dorsocaudal pathway from the dorsocaudal core field to the dorsocaudal belt area.

Encoding of learned importance of sound by magnitude of representational area in primary auditory cortex.

We hypothesized that learning-induced representational expansion in the primary auditory cortex (AI) directly encodes the degree of behavioral importance of a sound. Rats trained on an operant auditory conditioning task were variably motivated to the conditioned stimulus (CS) through different levels of water deprivation. Mean performance values correlated with deprivation level, validating them as a measure of the overall control and, therefore, behavioral importance of the CS. Electrophysiological mapping revealed expanded representations of the CS, compared with other frequencies in experimental subjects, but not in naive or visually trained controls that received noncontingent CS tones. Importantly, representational area showed a significant positive correlation with mean performance levels for only the CS band, with significant effects for relative area in contrast to only modest changes in absolute area. CS representational expansion was asymmetric into high-frequency zones, thus performance level also was significantly correlated with the relative anterior-posterior location of the enlarged representation. An increased representation of low frequencies, related to the acoustic spectrum of the reward delivery equipment, also was discovered in both experimental and control trained subjects, supporting the conclusion that behaviorally important sounds gain representational area. Furthermore, there was a surprising reduction in total AI area for the experimental and control groups, compared with untrained naive subjects, indicating that the functional dimensions of AI are not fixed. Overall, the findings support the encoding of acquired stimulus importance based on representational size in AI.

Characterisation of multiple physiological fields within the anatomical core of rat auditory cortex.

The organisation and response properties of the rat auditory cortex were investigated with single and multi-unit electrophysiological recording. Two tonotopically organised 'core' fields, i.e. the primary (A1) and anterior (AAF) auditory fields, as well as three non-tonotopically organised 'belt' fields, i.e. the posterodorsal (PDB), dorsal (DB) and anterodorsal (ADB) belt fields, were identified. Compared to neurones in A1, units in AAF exhibited broader frequency tuning, as well as shorter minimum, modal and mean first spike latencies. In addition, units in AAF showed significantly higher thresholds and best SPLs, as well as broader dynamic ranges. Units in PDB, DB and ADB were characterised by strong responses to white noise and showed either poor or no responses to pure tones. The differences in response properties found between the core and belt fields may reflect a functional specificity in processing different features of auditory stimuli. The present study also combined microelectrode mapping with Nissl staining to determine if the physiological differences between A1 and AAF corresponded to cytoarchitectonically defined borders. Both A1 and AAF were located within temporal cortex 1 (Te1), with AAF occupying an anteroventral subdivision of Te1, indicating that the two neighbouring, physiologically distinct fields are cytoarchitectonically homogeneous.

Spectrotemporal receptive field properties of single units in the primary, dorsocaudal and ventrorostral auditory cortex of the guinea pig.

We report the spectrotemporal response properties of single units in the primary (A1) and dorsocaudal (DC) fields, and the ventrorostral belt of the urethane-anaesthetised guinea pig auditory cortex. Using reverse correlation analysis, spectrotemporal receptive fields (STRFs) were constructed and subsequently classified according to a novel qualitative scheme that was based on the duration and bandwidth of excitatory and inhibitory regions within the STRF. The STRFs of units in both A1 and DC showed either broad-band (> or = 1 octave) or narrow-band (< 1 octave) excitatory and inhibitory regions occurring either alone or together. The excitatory regions were of short duration (lasting for <50 ms) or more sustained (up to about 100 ms) and inhibitory areas either followed excitation or were located as inhibitory sidebands along the high- and low-frequency edges of the excitatory regions. Inhibitory areas that followed excitatory regions were found to be either short lasting (10-20 ms) or longer lasting (up to 200 ms or more). The STRFs recorded from each cortical area indicated temporal response properties consistent with those shown by traditional peristimulus time histogram analysis. Overall, fields A1 and DC showed no significant differences in the distribution of STRF types. Thus, it appears that both fields display similar spectrotemporal sensitivities to auditory stimuli and therefore, appear to process such stimuli in a parallel fashion. Single units recorded in the ventrorostral belt area showed STRF types similar to those recorded in A1 and DC. However, the proportions of STRF types were significantly different, suggesting a difference in spectrotemporal processing between the ventrorostral belt and the core areas.

Interconnections of auditory areas in the guinea pig neocortex.

By studying the efferent projections of five auditory areas in the guinea pig cortex, we sought evidence that the larger fields can be divided into subareas based on unique patterns of cortical connections. Small extracellular injections of biocytin were made in combination with evoked potential mapping or single-unit analysis and histochemical determination of cortical landmarks. The two core fields, primary (AI) and dorsocaudal (DC), are partially surrounded by six adjacent belt areas, leaving two gaps: one at the rostral edge of AI and the other at the dorsal edge. All of the areas studied projected to their nearest neighbors, but AI was the only area to project to all seven of the other auditory areas. The caudal, high-frequency (more than 4 kHz) end of AI had different projections from the rostral, low-frequency (less than 1.5 kHz) end, and there was no evidence of connections between the two ends. Each end had separate dorsal and ventral projections. The two ends of AI may be working independently. By contrast, area DC had strong connections between its high- and low-frequency ends and it may be involved in auditory/visual integration. The dorsorostral belt (DRB) was subdivided into two zones on the basis of its projections: the more rostral part appears to overlap the second somatosensory area and be bimodal, while the caudal part has stronger auditory connections. The small belt area (area S) had separate physiological and anatomical properties from the rest of the rostral belt.