Updates

By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, Section Editor: Updates; is Associate Editor for Infectious Disease Alert.

There's a Fly in My Soupy Tissue

Source: Mowlavi GH, et al. Fatal nosocomial myiasis caused by Lucilia sericata (letter). J Hosp Infect 2011;78:338-339.

Unless you were bent on becoming a forensic entomologist as a kid, there is nothing worse than pulling back a bed sheet and finding ... maggots. Every so many years, I find an ICU patient, typically sedated and intubated, with fly larvae crawling out of some orifice or wound.

This brief report describes a 54-year-old woman with acute respiratory distress syndrome requiring prolonged intubation, status 22 days post-CABG. She was found to have maggots crawling out of her nose, around her endotracheal tube, and filling her sinuses. The larvae were reared, and identified as those of the green bottle fly, Lucilia sericata, which is a common type of blow fly that generally lays its eggs in devitalized tissue or open, foul-smelling wounds. In fact, the fly so reliably lays its eggs in cadaver tissue within hours of death, forensic investigators use the age of the maggots to determine time of death. The patient had inflamed nostrils, coated with petroleum jelly. In total, 75 larvae were removed from her nostrils, but continued to fill her maxillary, ethmoid, and sphenoid sinuses, and possibly her airways.

Unfortunately, the patient became increasingly unstable, precluding more aggressive efforts to remove the larvae. The authors believed the infestation contributed to her death.

Although an infrequent occurrence, flies are an important infection control issue for hospitals — and one of the reasons that windows and doors are kept shut at all times. Visitors can unknowingly carry insects on their clothing, packages, or flowers. Unconscious patients, especially those intubated and sedated in the ICU, cannot fend off flies. Many physicians do not realize that even one fly in the ICU requires attention.

Over-treatment of Urinary Tract Infections

Source: Rotjanapan P, et al. Potentially inappropriate treatment of urinary tract infections in two Rhode Island nursing homes. Arch Intern Med 2011;171:438-443.

I found this paper devastatingly in line with my everyday experience as an ID consultant. How many times have we been asked to consult on a frail older nursing home lady with "recurrent UTIs," who has received repeated courses of antibiotics. She is often asymptomatic or the urinalysis does not support a diagnosis of urinary tract infection by current criteria. She can barely stand, let alone provide a "clean catch." By the time I see her, she has developed a severe vaginal yeast infection from all the antibiotics, which is then causing "symptoms," but no one ever looks "down there."

These authors examined the use of antibacterials used for "urinary tract infection" in two nursing homes during a 6-month period in 2008. Once patients with Foley catheters, stones, and pyelonephritis were excluded, 132 patients with a total of 172 "episodes" of urine specimens being obtained were included in the analysis. The mean age of these case-patients was 83 years (range, 65-99 years); 78% were female. Nearly half (48%) of the specimens were obtained in persons with moderate-to-severe cognitive impairment; 7% were totally dependent.

Of the 172 cases, 26 (15%) met current criteria for a UTI, 100% of whom received antibacterials. A total of 146 (85%) cases did not meet current criteria for infection, many of which were asymptomatic bacteruria without pyuria.1 Despite this, antibiotics were administered to 70 (41%) of these cases. Women were 2.4 times more likely to receive antibacterials than men. Empiric antibacterials were administered in 27 cases before the results of urine studies were available; two-thirds of this was fluoroquinolones.

Of the 96 cases that were treated with antibiotics, only 26% met criteria for appropriate antibacterial use. The mean duration of antibiotics was 7.8 days (range, 3-14 days). Based on current Infectious Disease Society of America guidelines, two-thirds of the cases received antibiotics for longer than justified. Nearly half (46%) of the antibiotic selected was either considered inappropriate or an incorrect dose based on patient age, weight, and renal function (12 patients with normal renal function received inadequate dosing, and 14 patients received trimethoprim-sulfamethoxazole or nitrofurantoin, despite CrCl < 30 mL/min).

Sadly, 11 of the 96 case-patients who received antibacterials developed Clostridium difficile infection within 3 weeks of antibacterial use. Ironically, all 11 had received unnecessary antibiotics. None of the 76 patients who did not receive antibiotics experienced problems or consequences from a lack of treatment.

Careful interpretation of urine test results based on current criteria should guide the decision whether to treat. Empiric treatment for 3 days pending test results may be reasonable, keeping in mind that most patients with asymptomatic bacteruria do just fine without antibiotics.

Reference

  1. McGeer A, et al. Definitions of infection for surveillance in long-term care facilities. Am J Infect Control 1991;19:1-7.

HIV Integrase Inhibitor Resistance: What Do We Know?

Source: Blanco JL, et al. HIV-1 integrase inhibitor resistance and its clinical implications. J Infect Dis 2011;203:1204-1214.

Since its introduction in 2007, raltegravir has proven useful in combination multi-drug regimens for salvage therapy in patients with multi-drug resistant virus, as well as simplification of treatment regimens in patients beginning treatment. Two new integrase inhibitors (INI), elvitegravir (EVG) and S/GSK1349572, may have similar value.

De novo resistance to raltegravir is rare (< 0.1% of HIV+ patients). This class of drugs is, however, limited by its "vulnerability" — meaning drug-resistant virus can develop fairly readily in some patients, generally within the first few months of drug use. Only one or two genetic mutations appear necessary to significantly reduce the agent's virologic efficacy, and there is likely significant (but not complete) cross-resistance to other members of its class. Similar to the non-nucleoside reverse transcriptase inhibitors, diminished INI susceptibility is caused by a primary mutation, coupled with one or more secondary mutations, which either further reduce susceptibility or affect viral fitness. Fortunately, most patients with low-level virological rebound while receiving raltegravir do not have evidence of INI resistance.

This article summarizes the viral mutations observed either in vitro or in patients receiving INIs. Although good clinical data are not yet available to provide phenotypic cut-offs or clinical validation of these suspected mutations, a number of mutations have been identified as likely significant for reduced susceptibility to INIs.

The two most common combinations of mutations observed in vitro or in patients receiving INIs include Q148HRK + G140SAC, and N1554 ± E92Q, which appear also to cause EVG cross-resistance. A third common resistance pathway appears to be Y143CR ± T97A, which does not appear to cause EVG cross-resistance. The S/GSK1349572 compound demonstrates 10- to 20-fold diminished efficacy to isolates with the former combination of mutations, but appears fully active against isolates with either of the latter combination mutations.

Although good clinical data correlating these findings are not yet available, patients with these three major mutations (Y143CR, Q148HRK, N155H) are not likely to respond to raltegravir. It is possible, however, that future INI products, including those in development, may remain active against some raltegravir-resistant isolates.

Childhood Polio in India

Source: Doshi SJ, et al. Poliomyelitis-related case-fatality ratio in India, 2002-2006. Clin Infect Dis 2011;53:13-19.

These authors assessed the case-fatality rate (CFR) of acute poliovirus infection in India from 2002 to 2006. Following an outbreak in 2002, the Acute Flacid Paralysis (AFP) Surveillance System amended its protocols for case definition, and an AFP Medical Officer was assigned to the Moradabad district in Utter Pradesh, which had been hardest hit by the infection. This allowed for enhanced surveillance and tracking of cases in this area of concern; all cases were reported within a week, and the mean time from notification to investigation decreased to < 1 day, and the time from onset of paralysis to investigation was 3.5 days.

During the 2002 outbreak, 1,600 WPV cases occurred, for which 1,584 had follow-up data. The overall CFR was 4.1%. During the 2006 outbreak, 676 cases of WPV infection occurred, for which 673 had follow-up data. The CFR was 6.7% (7.3% for WPV1 infection and 0% for WPV3 infection). Children < 5 years of age accounted for 98% of the deaths in 2002 and 100% of the deaths in 2006. Of these, 73% were in children < age 2 — yielding a significantly higher death rate (16%) in this age group than previously recognized. More than 70% of the fatal cases in children reportedly had received 3 or more doses of polio vaccine, which points to some serious flaws in the administration of the poliovirus vaccine to children, with obvious misrepresentation by parents and/or schools in the area.